National Library of Energy BETA

Sample records for flame space shuttle

  1. Experimental Endeavour on a Pillar of Flame: Space Shuttle Rises...

    Energy Savers [EERE]

    Experiment Aboard Friday's Space Shuttle Launch An optical micrograph of a polymer film that self-assembles into ordered nanoscale structures. | Photo Courtesy of Argonne...

  2. Space Shuttle Program Status

    E-Print Network [OSTI]

    Waliser, Duane E.

    Payload: 36th ISS flight (ULF6), EXPRESS Logistics Carrier 3 (ELC3), Alpha Magnetic Spectrometer (AMS;8 Transition #12;9 Major Space Shuttle Program Facilities Reusable Solid Rocket Motor ATK Thiokol Propulsion

  3. United States Space Shuttle Firsts

    E-Print Network [OSTI]

    for the open sea test on shuttle retrieval performed at Port Everglades, Florida. 05/01/1979 Enterprise · First. Peterson, S. Musgrave · First flight of the orbiter Challenger. · First Tracking and Data Relay Satellite

  4. A Thought of Wrapping Space Shuttle External Tank with Ceramic Fiber Fishnet Stockings

    E-Print Network [OSTI]

    Sun Hong Rhie

    2006-03-14

    The new camera system of the shuttle Discovery on STS-114 that blasted off at 10:39am, Tuesday, July 26, 2005, after 906 days of grounding since the Columbia accident, has produced high resolution data of foam sheddings. The 0.9 lbs piece from the Protuberance Air Load (PAL) ramp on the LH2 tank is believed to be comparable in its potential adversities to the $\\sim 1.67$ lbs BX-250 foam from the $-Y$ bipod ramp that demised shuttle Columbia in 2003. The two known incidences indicate that protuberant foams, possibly in conjunction with the liquid hydrogen temperature, offer lame targets of the aerodynamic forces. Seven other relatively large divots in the STS-114 external tank foam insulation have been reported, and foam shedding remains to be a challenge to be resolved before the next space shuttle launch. The relatively large divots from the newly streamlined foam around the -Y bipod area suggests a potential necessity for a new line of resolution. We suggest an option to wrap the insulated external fuel tank with a grid of high temperature resistant ceramic fibers ({\\it ceramic fiber fishnet stockings}). Assuming fiducial acreage of $20000 ft^2 $, one inch square cell single fiber grid will weigh only $60g$ with fiber cost \\$66. Even with 1500-fiber-equivalent strength, one inch square cell grid will add only $200 lbs$ and "miniscule" \\$100,000.

  5. Experimental Endeavour on a Pillar of Flame: Space Shuttle Rises with

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirleyEnergy A plug-inPPLfor InnovativeProcessing22,673, proposedJanuary andTechnology Centers

  6. Risk Analysis of the Space Shuttle: Pre-Challenger Bayeisan Prediction of Failure

    SciTech Connect (OSTI)

    Dana L. Kelly

    2008-02-01

    Dalal et al performed a statistical analysis of field and nozzle O-ring data collected prior to the ill-fated launch of the Challenger in January 1986. The purpose of their analysis was to show how statistical analysis could be used to provide information to decisionmakers prior to the launch, information that could have been expected to lead to a decision to abort the launch due to the low temperatures (~30o F.) present at the launch pad on the morning of the scheduled launch. Dalal et al. performed a frequentist analysis of the O-ring data, and found that a logistic regression model provided a relatively good fit to the past data. In the second portion of their paper, Dalal et al. propagated parameter uncertainties through the fitted logistic regression model in order to estimate the probability of shuttle failure due to O-ring failure at the estimated launch temperature of ~30o F. Because their analysis was frequentist in nature, probability distributions representing epistemic uncertainty in the input parameters were not available, and the authors had to resort to an approximate approach based on bootstrap confidence intervals. In this paper, we will re-evaluate the analyses of Dalal et al. from a Bayesian perspective. Markov chain Monte Carlo (MCMC) sampling will be used to sample from the joint posterior distribution of the model parameters, and to sample from the posterior predictive distributions at the estimated launch temperature, a temperature that had not been observed in prior launches of the space shuttle. Uncertainties, which are represented by probability distributions in the Bayesian approach, are propagated through the model to obtain a probability distribution for O-ring failure, and subsequently for shuttle failure as a result of O-ring failure. No approximations are required in the Bayesian approach and the resulting distributions can be input to a decision analysis to obtain expected utility for the decision to launch.

  7. Title: Shuttle Radar Topography Mission (SRTM) Data Creator /

    E-Print Network [OSTI]

    Title: Shuttle Radar Topography Mission (SRTM) Data Creator / Copyright Owner: National Aeronautics@yorku.ca Citation: National Aeronautics and Space Administration. "Shuttle Radar Topography Mission (SRTM

  8. Densitometric analysis of IIaO film flown aboard the space shuttle transportation system STS-3, STS-8, and STS-7. Semiannual report, December 1986

    SciTech Connect (OSTI)

    Hammond, E.C. Jr.; Peters, K.A.; Atkinson, P.F.

    1986-01-01

    Three canisters of IIaO film were prepared along with packets of color film from the National Geographic Society, which were then placed on the Space Shuttle number3. The ultimate goal was to obtain reasonably accurate data concerning the background fogging effects on IIaO film as it relates to the film's total environmental experience. This includes: the ground based packing, and loading of the film from Goddard Space Flight Center to Cape Kennedy; the effects of the solar wind, humidity, and cosmic rays; the Van Allen Belt radiation exposure; various thermal effect; reentry and off-loading of the film during take off, and 8 day, 3 hour 15 minutes orbits. The total densitometric change caused by all of the above factors were examined. The results of these studies have implications for the utilization of IIaO spectroscopic film on the future shuttle and space lab missions. These responses to standard photonic energy sources will have immediate application for the uneven responses of the film photographing a star field in a terrestrial or extraterrestrial environment with associated digital imaging equipment.

  9. Flame Height Measurement of Laminar Inverse Diffusion Flames

    E-Print Network [OSTI]

    Mikofski, Mark A.; Williams, Timothy C.; Shaddix, Christopher R.; Blevins, Linda G.

    2006-01-01

    Flame Height Measurement of Laminar Inverse Diffusion Flamesinverse diffusion flame, laminar, flame height, OH, laserair and methane-air laminar inverse diffusion flames were

  10. Sandia Energy - Flame Chemistry

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Flame Chemistry Home Transportation Energy Predictive Simulation of Engines Combustion Chemistry Flame Chemistry Flame ChemistryAshley Otero2015-10-28T02:43:31+00:00 Research in...

  11. Understanding IV&V in a Safety Critical and Complex Evolutionary Environment: The NASA Space Shuttle Program1

    E-Print Network [OSTI]

    Zelkowitz, Marvin V.

    Understanding IV&V in a Safety Critical and Complex Evolutionary Environment: The NASA Space, Maryland 20740, USA +1-301-403-8971 irus@fc-md.umd.edu 1 This work has been performed as NASA Subcontract No. 93-393B-FUSA from the NASA/IVV facility in Fairmont, WV to the Fraunhofer Center, Maryland

  12. FLAT FLAME BURNER ANALYSES

    E-Print Network [OSTI]

    Pagni, P.J.

    2012-01-01

    in Edge Cooled F1at Flame Burners," Combust. Sci. and Tech.Subscripts w water b burner ambient, upstream bondary ufor publication FLAT FLAME BURNER ANALYSES P. J. Pagni, A.

  13. Extremely weak hydrogen flames

    SciTech Connect (OSTI)

    Lecoustre, V.R.; Sunderland, P.B. [Department of Fire Protection Engineering, University of Maryland, College Park, MD 20742 (United States); Chao, B.H. [Department of Mechanical Engineering, University of Hawaii, Honolulu, HI 96822 (United States); Axelbaum, R.L. [Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63130 (United States)

    2010-11-15

    Hydrogen jet diffusion flames were observed near their quenching limits. These involved downward laminar flow of hydrogen from a stainless steel hypodermic tube with an inside diameter of 0.15 mm. Near their quenching limits these flames had hydrogen flow rates of 3.9 and 2.1 {mu}g/s in air and oxygen, respectively. Assuming complete combustion, the associated heat release rates are 0.46 and 0.25 W. To the authors' knowledge, these are the weakest self-sustaining steady flames ever observed. (author)

  14. Structure of hydrogen triple flames and premixed flames compared

    SciTech Connect (OSTI)

    Owston, Rebecca; Abraham, John

    2010-08-15

    Triple flames consisting of lean, stoichiometric, and rich reaction zones may be produced in stratified mixtures undergoing combustion. Such flames have unique characteristics that differ from premixed flames. The present work offers a direct comparison of the structure and propagation behavior between hydrogen/air triple and premixed flames through a numerical study. Important similarities and differences are highlighted. Premixed flames are generated by spark-igniting initially quiescent homogeneous mixtures of hydrogen and air in a two-dimensional domain. Triple flame results are also generated in a two-dimensional domain by spark-igniting initially quiescent hydrogen/air stratified layers. Detailed flame structure and chemical reactivity information is collected along isocontours of equivalence ratio 0.5, 1.0, and 3.0 in the triple flame for comparison with premixed flames at the same equivalence ratios. Full chemistry and effective binary diffusion coefficients are employed for all computations. (author)

  15. Project Profile: Carbon Dioxide Shuttling Thermochemical Storage...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Project Profile: Carbon Dioxide Shuttling Thermochemical Storage Using Strontium Carbonate Project Profile: Carbon Dioxide Shuttling Thermochemical Storage Using Strontium...

  16. Electrical probe diagnostics for the laminar flame quenching distance

    SciTech Connect (OSTI)

    Karrer, Maxime; Makarov, Maxime; Bellenoue, Marc; Labuda, Sergei; Sotton, Julien

    2010-02-15

    A simplified theory, previously developed for the general case of weakly ionized gas flow, is used to predict electrical probe response when the flame is quenched on the probe surface. This theory is based on the planar model of space charge sheaths around the measuring electrode. For the flame quenching case, by assuming that the sheath thickness is comparable with the thermal boundary layer thickness, probe current can be related to flame quenching distance. The theoretical assumptions made to obtain the analytical formulation of probe current were experimentally proved by using direct visualization and high-frequency PIV. The direct visualization method was also used to validate the results of flame quenching distance values obtained with electrical probe. The electrical probe diagnostics have been verified for both head-on and sidewall flame quenching regimes and for stoichiometric methane/air and propane/air mixtures in a pressure range of 0.05-0.6 MPa. (author)

  17. Strained flamelets for turbulent premixed flames II: Laboratory flame results

    SciTech Connect (OSTI)

    Kolla, H.; Swaminathan, N. [Department of Engineering, Cambridge University, Cambridge CB2 1PZ (United Kingdom)

    2010-07-15

    The predictive ability of strained flamelets model for turbulent premixed flames is assessed using Reynolds Averaged Navier Stokes (RANS) calculations of laboratory flames covering a wide range of conditions. Reactant-to-product (RtP) opposed flow laminar flames parametrised using the scalar dissipation rate of reaction progress variable are used as strained flamelets. Two turbulent flames: a rod stabilised V-flame studied by Robin et al. [Combust. Flame 153 (2008) 288-315] and a set of pilot stabilised Bunsen flames studied by Chen et al. [Combust. Flame 107 (1996) 223-244] are calculated using a single set of model parameters. The V-flame corresponds to the corrugated flamelets regime. The strained flamelet model and an unstrained flamelet model yield similar predictions which are in good agreement with experimental measurements for this flame. On the other hand, for the Bunsen flames which are in the thin reaction zones regime, the unstrained flamelet model predicts a smaller flame brush compared to experiment. The predictions of the strained flamelets model allowing for fluid-dynamics stretch induced attenuation of the chemical reaction are in good agreement with the experimental data. This model predictions of major and minor species are also in good agreement with experimental data. The results demonstrate that the strained flamelets model using the scalar dissipation rate can be used across the combustion regimes. (author)

  18. Solid Flame: Fundamentals and

    E-Print Network [OSTI]

    Mukasyan, Alexander

    to produce heat and light, seen as a flame · the burning of fuel in an engine to provide power Combustion or burning is a complex sequence of exothermic chemical reactions between a fuel and an oxidant accompaniedJ/mol Tantalum carbide (TaC) is an extremely hard refractory (3880°C; 4153 K) ceramic material, commercially used

  19. The effect of stoichiometry on vortex flame interactions

    SciTech Connect (OSTI)

    Bell, John B.; Brown, Nancy J.; Day, Marcus S.; Frenklach, Michael; Grcar, Joseph F.; Tonse, Shaheen R.

    1999-12-01

    The interaction of a vortex pair with a premixed flame serves as an important prototype for premixed turbulent combustion. In this study, the authors investigate the interaction of a counter-rotating vortex pair with an initially flat premixed methane flame. The authors focus on characterizing the mechanical nature of the flame-vortex interaction and on the features of the interaction strongly affected by fuel equivalence ratio. The authors compare computational solutions obtained using a time-dependent, two-dimensional adaptive low Mach number combustion algorithm that incorporates GRI-Mech 1.2 for the chemistry, thermodynamics and transport of the chemical species. The authors find that the circulation around the vortex scours gas from the preheat zone in front of the flame, making the interaction extremely sensitive to equivalence ratio. For nearly stoichiometric cases, the peak mole fraction of CH across the flame is relatively insensitive to the vortex whereas for richer flames they observe a substantial and rapid decline in the peak CH mole fraction, commencing early in the flame-vortex interaction. The peak concentration of HCO is found to correlate, in both space and time, with the peak heat release across a broad range of equivalence ratios. The model also predicts a measurable increase in C{sub 2}H{sub 2} as a result of interaction with the vortex, and a marked increase in the low temperature chemistry activity.

  20. 3rd European Conference for AeroSpace Sciences (EUCASS) Paper 2009-374 1 THE RESPONSE OF PREMIXED FLAMES TO PRESSURE OSCILLATIONS

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    3rd European Conference for AeroSpace Sciences (EUCASS) Paper 2009-374 1 THE RESPONSE OF PREMIXED rate. hal-00418835,version1-21Sep2009 Author manuscript, published in "3rd European Conference for Aerospace Sciences (EUCASS), Versailles : France (2009)" #12;3rd European Conference for AeroSpace Sciences

  1. Dynamics and structure of stretched flames

    SciTech Connect (OSTI)

    Law, C.K. [Princeton Univ., NJ (United States)

    1993-12-01

    This program aims to gain fundamental understanding on the structure, geometry, and dynamics of laminar premixed flames, and relate these understanding to the practical issues of flame extinction and stabilization. The underlying fundamental interest here is the recent recognition that the response of premixed flames can be profoundly affected by flame stretch, as manifested by flow nonuniformity, flame curvature, and flame/flow unsteadiness. As such, many of the existing understanding on the behavior of premixed flames need to be qualitatively revised. The research program consists of three major thrusts: (1) detailed experimental and computational mapping of the structure of aerodynamically-strained planar flames, with emphasis on the effects of heat loss, nonequidiffusion, and finite residence time on the flame thickness, extent of incomplete reaction, and the state of extinction. (2) Analytical study of the geometry and dynamics of stretch-affected wrinkled flame sheets in simple configurations, as exemplified by the Bunsen flame and the spatially-periodic flame, with emphasis on the effects of nonlinear stretch, the phenomena of flame cusping, smoothing, and tip opening, and their implications on the structure and burning rate of turbulent flames. (3) Stabilization and blowoff of two-dimensional inverted premixed and stabilization and determining the criteria governing flame blowoff. The research is synergistically conducted through the use of laser-based diagnostics, computational simulation of the flame structure with detailed chemistry and transport, and mathematical analysis of the flame dynamics.

  2. Production Of Fullerenic Soot In Flames

    DOE Patents [OSTI]

    Howard, Jack B. (Winchester, MA); Vander Sande, John B. (Newbury, MA); Chowdhury, K. Das (Cambridge, MA)

    2000-12-19

    A method for the production of fullerenic nanostructures is described in which unsaturated hydrocarbon fuel and oxygen are combusted in a burner chamber at a sub-atmospheric pressure, thereby establishing a flame. The condensibles of the flame are collected at a post-flame location. The condensibles contain fullerenic nanostructures, such as single and nested nanotubes, single and nested nanoparticles and giant fullerenes. The method of producing fullerenic soot from flames is also described.

  3. Premixed-gas flames Paul D. Ronney

    E-Print Network [OSTI]

    Premixed-gas flames Paul D. Ronney Department of Aerospace and Mechanical Engineering University of Southern California, Los Angeles, CA 90089-1453 USA ronney@usc.edu Keywords: Microgravity; premixed-gas; cool flames; turbulence. Reference: Ronney, P. D., "Premixed-Gas Flames," in: Microgravity Combustion

  4. Flex-flame burner and combustion method

    DOE Patents [OSTI]

    Soupos, Vasilios (Chicago, IL); Zelepouga, Serguei (Hoffman Estates, IL); Rue, David M. (Chicago, IL); Abbasi, Hamid A. (Naperville, IL)

    2010-08-24

    A combustion method and apparatus which produce a hybrid flame for heating metals and metal alloys, which hybrid flame has the characteristic of having an oxidant-lean portion proximate the metal or metal alloy and having an oxidant-rich portion disposed above the oxidant lean portion. This hybrid flame is produced by introducing fuel and primary combustion oxidant into the furnace chamber containing the metal or metal alloy in a substoichiometric ratio to produce a fuel-rich flame and by introducing a secondary combustion oxidant into the furnace chamber above the fuel-rich flame in a manner whereby mixing of the secondary combustion oxidant with the fuel-rich flame is delayed for a portion of the length of the flame.

  5. Nonlinear effects in the extraction of laminar flame speeds from expanding spherical flames

    SciTech Connect (OSTI)

    Kelley, A.P.; Law, C.K.

    2009-09-15

    Various factors affecting the determination of laminar flames speeds from outwardly propagating spherical flames in a constant-pressure combustion chamber were considered, with emphasis on the nonlinear variation of the stretched flame speed to the flame stretch rate, and the associated need to nonlinearly extrapolate the stretched flame speed to yield an accurate determination of the laminar flame speed and Markstein length. Experiments were conducted for lean and rich n-butane/air flames at 1atm initial pressure, demonstrating the complex and nonlinear nature of the dynamics of flame evolution, and the strong influences of the ignition transient and chamber confinement during the initial and final periods of the flame propagation, respectively. These experimental data were analyzed using the nonlinear relation between the stretched flame speed and stretch rate, yielding laminar flame speeds that agree well with data determined from alternate flame configurations. It is further suggested that the fidelity in the extraction of the laminar flame speed from expanding spherical flames can be facilitated by using small ignition energy and a large combustion chamber. (author)

  6. Experimental study of turbulent flame kernel propagation

    SciTech Connect (OSTI)

    Mansour, Mohy [National Institute of Laser Enhanced Sciences, Cairo University, Giza (Egypt); Peters, Norbert; Schrader, Lars-Uve [Institute of Combustion Technology, Aachen (Germany)

    2008-07-15

    Flame kernels in spark ignited combustion systems dominate the flame propagation and combustion stability and performance. They are likely controlled by the spark energy, flow field and mixing field. The aim of the present work is to experimentally investigate the structure and propagation of the flame kernel in turbulent premixed methane flow using advanced laser-based techniques. The spark is generated using pulsed Nd:YAG laser with 20 mJ pulse energy in order to avoid the effect of the electrodes on the flame kernel structure and the variation of spark energy from shot-to-shot. Four flames have been investigated at equivalence ratios, {phi}{sub j}, of 0.8 and 1.0 and jet velocities, U{sub j}, of 6 and 12 m/s. A combined two-dimensional Rayleigh and LIPF-OH technique has been applied. The flame kernel structure has been collected at several time intervals from the laser ignition between 10 {mu}s and 2 ms. The data show that the flame kernel structure starts with spherical shape and changes gradually to peanut-like, then to mushroom-like and finally disturbed by the turbulence. The mushroom-like structure lasts longer in the stoichiometric and slower jet velocity. The growth rate of the average flame kernel radius is divided into two linear relations; the first one during the first 100 {mu}s is almost three times faster than that at the later stage between 100 and 2000 {mu}s. The flame propagation is slightly faster in leaner flames. The trends of the flame propagation, flame radius, flame cross-sectional area and mean flame temperature are related to the jet velocity and equivalence ratio. The relations obtained in the present work allow the prediction of any of these parameters at different conditions. (author)

  7. DOE HQ Shuttle Bus Route and Schedule

    Office of Environmental Management (EM)

    of each route. The shuttle bus departure and arrival times may be impacted by traffic, weather, or other logistical interruptions. Headquarters employees are reminded of the...

  8. Shuttle Schedule | Department of Energy

    Energy Savers [EERE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION J APPENDIX E LIST OF APPLICABLE DIRECTIVES Pursuant to theDepartmentWorkalongShaleSherrellShuttle

  9. Investigation of Flame Stretch in Turbulent Lifted Jet Flame

    E-Print Network [OSTI]

    Ruan, S.; Swaminathan, N.; Mizobuchi, Y.

    2014-02-24

    jet flame, Mixed mode combustion, 2 1 Introduction The occurrence of mixed mode combustion in many practical devices such as strati- fied charge direct injection engines and lean burn gas turbine combustor is common. In these devices, typically fuel... ., 2009; Richardson et al., 2010; Chakraborty et al., 2010) and experimental (Hartung et al., 2008; Steinberg et al., 2012) studies of premixed combustion and stratified combustion (Malkeson and Chakraborty, 2011) have demonstrated that the reactive scalar...

  10. Novel Redox Shuttles for Overcharge Protection of Lithium-Ion...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Redox Shuttles for Overcharge Protection of Lithium-Ion Batteries Technology available for licensing: Electrolytes containing novel redox shuttles (electron transporters) for...

  11. AVTA: Idaho National Laboratory Experimental Hybrid Shuttle Bus...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Idaho National Laboratory Experimental Hybrid Shuttle Bus Testing Results AVTA: Idaho National Laboratory Experimental Hybrid Shuttle Bus Testing Results The Vehicle Technologies...

  12. Laminar Flame Speeds of Nano-Aluminum/Methane Hybrid Mixtures 

    E-Print Network [OSTI]

    Sikes, Travis

    2014-12-12

    An existing flame speed bomb, which uses optical techniques to measure laminar flame speed, was employed to study the fundamental phenomena of flame propagation through a uniformly dispersed aerosol. In a previous thesis ...

  13. The interaction of high-speed turbulence with flames: Global properties and internal flame structure

    SciTech Connect (OSTI)

    Poludnenko, A.Y.; Oran, E.S. [Laboratory for Computational Physics and Fluid Dynamics, Naval Research Laboratory, Washington, DC 20375 (United States)

    2010-05-15

    We study the dynamics and properties of a turbulent flame, formed in the presence of subsonic, high-speed, homogeneous, isotropic Kolmogorov-type turbulence in an unconfined system. Direct numerical simulations are performed with Athena-RFX, a massively parallel, fully compressible, high-order, dimensionally unsplit, reactive flow code. A simplified reaction-diffusion model represents a stoichiometric H{sub 2}-air mixture. The system being modeled represents turbulent combustion with the Damkoehler number Da=0.05 and with the turbulent velocity at the energy injection scale 30 times larger than the laminar flame speed. The simulations show that flame interaction with high-speed turbulence forms a steadily propagating turbulent flame with a flame brush width approximately twice the energy injection scale and a speed four times the laminar flame speed. A method for reconstructing the internal flame structure is described and used to show that the turbulent flame consists of tightly folded flamelets. The reaction zone structure of these is virtually identical to that of the planar laminar flame, while the preheat zone is broadened by approximately a factor of two. Consequently, the system evolution represents turbulent combustion in the thin reaction zone regime. The turbulent cascade fails to penetrate the internal flame structure, and thus the action of small-scale turbulence is suppressed throughout most of the flame. Finally, our results suggest that for stoichiometric H{sub 2}-air mixtures, any substantial flame broadening by the action of turbulence cannot be expected in all subsonic regimes. (author)

  14. A Flamelet Description of Premixed Laminar Flames and the Relation with Flame Stretch

    E-Print Network [OSTI]

    Eindhoven, Technische Universiteit

    1 A Flamelet Description of Premixed Laminar Flames and the Relation with Flame Stretch L.P.H. de of Mathematics and Computing Science, PO Box 513, 5600MB Eindhoven, The Netherlands ABSTRACT ­ A laminar flamelet description is derived for premixed laminar flames. The full set of 3D instationary combustion equations

  15. Chemical Shuttle Additives in Lithium Ion Batteries

    SciTech Connect (OSTI)

    Patterson, Mary

    2013-03-31

    The goals of this program were to discover and implement a redox shuttle that is compatible with large format lithium ion cells utilizing LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2} (NMC) cathode material and to understand the mechanism of redox shuttle action. Many redox shuttles, both commercially available and experimental, were tested and much fundamental information regarding the mechanism of redox shuttle action was discovered. In particular, studies surrounding the mechanism of the reduction of the oxidized redox shuttle at the carbon anode surface were particularly revealing. The initial redox shuttle candidate, namely 2-(pentafluorophenyl)-tetrafluoro-1,3,2-benzodioxaborole (BDB) supplied by Argonne National Laboratory (ANL, Lemont, Illinois), did not effectively protect cells containing NMC cathodes from overcharge. The ANL-RS2 redox shuttle molecule, namely 1,4-bis(2-methoxyethoxy)-2,5-di-tert-butyl-benzene, which is a derivative of the commercially successful redox shuttle 2,5-di-tert-butyl-1,4-dimethoxybenzene (DDB, 3M, St. Paul, Minnesota), is an effective redox shuttle for cells employing LiFePO{sub 4} (LFP) cathode material. The main advantage of ANL-RS2 over DDB is its larger solubility in electrolyte; however, ANL-RS2 is not as stable as DDB. This shuttle also may be effectively used to rebalance cells in strings that utilize LFP cathodes. The shuttle is compatible with both LTO and graphite anode materials although the cell with graphite degrades faster than the cell with LTO, possibly because of a reaction with the SEI layer. The degradation products of redox shuttle ANL-RS2 were positively identified. Commercially available redox shuttles Li{sub 2}B{sub 12}F{sub 12} (Air Products, Allentown, Pennsylvania and Showa Denko, Japan) and DDB were evaluated and were found to be stable and effective redox shuttles at low C-rates. The Li{sub 2}B{sub 12}F{sub 12} is suitable for lithium ion cells utilizing a high voltage cathode (potential that is higher than NMC) and the DDB is useful for lithium ion cells with LFP cathodes (potential that is lower than NMC). A 4.5 V class redox shuttle provided by Argonne National Laboratory was evaluated which provides a few cycles of overcharge protection for lithium ion cells containing NMC cathodes but it is not stable enough for consideration. Thus, a redox shuttle with an appropriate redox potential and sufficient chemical and electrochemical stability for commercial use in larger format lithium ion cells with NMC cathodes was not found. Molecular imprinting of the redox shuttle molecule during solid electrolyte interphase (SEI) layer formation likely contributes to the successful reduction of oxidized redox shuttle species at carbon anodes. This helps to understand how a carbon anode covered with an SEI layer, that is supposed to be electrically insulating, can reduce the oxidized form of a redox shuttle.

  16. Enol Intermediates Unexpectedly Found in Flames

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    intermediates, and major products. However, for improving combustion efficiency and controlling pollution, it is necessary to understand flame chemistry at the...

  17. Spark ignition of lifted turbulent jet flames

    SciTech Connect (OSTI)

    Ahmed, S.F.; Mastorakos, E. [Hopkinson Laboratory, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ (United Kingdom)

    2006-07-15

    This paper presents experiments on ignition and subsequent edge flame propagation in turbulent nonpremixed methane jets in air. The spark position, energy, duration, electrode diameter and gap, and the jet velocity and air premixing of the fuel stream are examined to study their effects on the ignition probability defined as successful flame establishment. The flame is visualized by a high-speed camera and planar laser-induced fluorescence of OH. It was found that after an initially spherical shape, the flame took a cylindrical shape with a propagating edge upstream. The probability of successful ignition increases with high spark energy, thin electrode diameter and wide gap, but decreases with increasing dilution of the jet with air. The flame kernel growth rate is high when the ignition probability is high for all parameters, except for jet velocity. Increasing the jet velocity decreases the ignition probability at all locations. The average flame position as a function of time from the spark was measured and the data were used to estimate a net propagation speed, which then resulted in an estimate of the average edge flame speed relative to the incoming flow. This was about 3 to 6 laminar burning velocities of a stoichiometric mixture. The measurements can assist theoretical models for the probability of ignition of nonpremixed flames and for edge flame propagation in turbulent inhomogeneous mixtures, both of which determine the success of ignition in practical combustion systems. (author)

  18. Enol Intermediates Unexpectedly Found in Flames

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    output, high-concentration intermediates, and major products. However, for improving combustion efficiency and controlling pollution, it is necessary to understand flame...

  19. Combustion measurements of an array of radial jet reattachment flames

    SciTech Connect (OSTI)

    Wu, J.; Seyed-Yagoobi, J.

    1999-07-01

    Radial Jet Reattachment Combustion (RJRC) nozzle provides improved fuel/air mixing for use in impingement flame heating. The RJRC nozzle produces a very stable flame with a circumferentially symmetric surface temperature profile and low coefficients of pressure on the impingement surface. The RJRC also produces very little soot. To characterize the performance of an array of RJRC nozzles from combustion point of view, exhaust gas analyses are presented through CO, CO{sub 2}, O{sub 2}, and NO{sub x} measurements. The results are also compared to the single RJRC nozzle combustion characteristics. In the array configuration, the highly, moderately, and weakly interactive RJRC nozzles are considered. The interaction among nozzles is highly dependent upon the between-nozzle spacing.

  20. Design, Modeling, and Validation of a Flame Reformer for LNT...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Design, Modeling, and Validation of a Flame Reformer for LNT External Bypass Regeneration Design, Modeling, and Validation of a Flame Reformer for LNT External Bypass Regeneration...

  1. Flame Interactions in Turbulent Premixed Twin V-flames

    E-Print Network [OSTI]

    Dunstan, T. D.; Swaminathan, N.; Bray, K. N. C.; Kingsbury, N. G.

    2013-01-16

    in Table 2, where u?in is the inlet rms velocity fluctuation, and l0 is the integral length scale in the frozen turbulence. The Karlovitz number is estimated from Ka ? (u?in/sL) 3 2 (l0/?)? 12 . The turbulent Reynolds and Damko¨hler numbers are Rel0 = u?inl... volume at a given location: ?c?=0.8 = (|?c|c?=0.8)P(c?), where P(c?) is the probability of finding c? = 0.8 at a given spatial location (Pope, 1988). The mean conditional gradient, |?c|c?=0.8, does not change significantly through 21 the flame brush...

  2. Active control for turbulent premixed flame simulations

    SciTech Connect (OSTI)

    Bell, John B.; Day, Marcus S.; Grcar, Joseph F.; Lijewski, Michael J.

    2004-03-26

    Many turbulent premixed flames of practical interest are statistically stationary. They occur in combustors that have anchoring mechanisms to prevent blow-off and flashback. The stabilization devices often introduce a level of geometric complexity that is prohibitive for detailed computational studies of turbulent flame dynamics. As a result, typical detailed simulations are performed in simplified model configurations such as decaying isotropic turbulence or inflowing turbulence. In these configurations, the turbulence seen by the flame either decays or, in the latter case, increases as the flame accelerates toward the turbulent inflow. This limits the duration of the eddy evolutions experienced by the flame at a given level of turbulent intensity, so that statistically valid observations cannot be made. In this paper, we apply a feedback control to computationally stabilize an otherwise unstable turbulent premixed flame in two dimensions. For the simulations, we specify turbulent in flow conditions and dynamically adjust the integrated fueling rate to control the mean location of the flame in the domain. We outline the numerical procedure, and illustrate the behavior of the control algorithm. We use the simulations to study the propagation and the local chemical variability of turbulent flame chemistry.

  3. Transient Supersonic Methane-Air Flames 

    E-Print Network [OSTI]

    Richards, John L.

    2012-07-16

    . The combustor was designed following well-known principles of jet engine combustors. A flame holder and spark plug combination was used to encourage turbulent mixing and ignition of reactant gases, and to anchor the transient flame. Combustion created a high...

  4. Jet flames of a refuse derived fuel

    SciTech Connect (OSTI)

    Weber, Roman; Kupka, Tomasz; Zajac, Krzysztof

    2009-04-15

    This paper is concerned with combustion of a refuse derived fuel in a small-scale flame. The objective is to provide a direct comparison of the RDF flame properties with properties of pulverized coal flames fired under similar boundary conditions. Measurements of temperature, gas composition (O{sub 2}, CO{sub 2}, CO, NO) and burnout have demonstrated fundamental differences between the coal flames and the RDF flames. The pulverized coals ignite in the close vicinity of the burner and most of the combustion is completed within the first 300 ms. Despite the high volatile content of the RDF, its combustion extends far into the furnace and after 1.8 s residence time only a 94% burnout has been achieved. This effect has been attributed not only to the larger particle size of fluffy RDF particles but also to differences in RDF volatiles if compared to coal volatiles. Substantial amounts of oily tars have been observed in the RDF flames even though the flame temperatures exceeded 1300 C. The presence of these tars has enhanced the slagging propensity of RDF flames and rapidly growing deposits of high carbon content have been observed. (author)

  5. On the extraction of laminar flame speed and Markstein length from outwardly propagating spherical flames

    SciTech Connect (OSTI)

    Chen, Zheng [State Key Laboratory for Turbulence and Complex Systems, Department of Mechanics and Aerospace Engineering, College of Engineering, Peking University, Beijing 100871 (China)

    2011-02-15

    Large discrepancies among the laminar flame speeds and Markstein lengths of methane/air mixtures measured by different researchers using the same constant-pressure spherical flame method are observed. As an effort to reduce these discrepancies, one linear model (LM, the stretched flame speed changes linearly with the stretch rate) and two non-linear models (NM I and NM II, the stretched flame speed changes non-linearly with the stretch rate) for extracting the laminar flame speed and Markstein length from propagating spherical flames are investigated. The accuracy and performance of the LM, NM I, and NM II are found to strongly depend on the Lewis number. It is demonstrated that NM I is the most accurate for mixtures with large Lewis number (positive Markstein length) while NM II is the most accurate for mixtures with small Lewis number (negative Markstein length). Therefore, in order to get accurate laminar flame speed and Markstein length from spherical flame experiments, different non-linear models should be used for different mixtures. The validity of the theoretical results is further demonstrated by numerical and experimental studies. The results of this study can be used directly in spherical flame experiments measuring the laminar flame speed and Markstein length. (author)

  6. Aromatics oxidation and soot formation in flames

    SciTech Connect (OSTI)

    Howard, J.B.; Pope, C.J.; Shandross, R.A.; Yadav, T. [Massachusetts Institute of Technology, Cambridge (United States)

    1993-12-01

    This project is concerned with the kinetics and mechanisms of aromatics oxidation and soot and fullerenes formation in flames. The scope includes detailed measurements of profiles of stable and radical species concentrations in low-pressure one-dimensional premixed flames. Intermediate species identifications and mole fractions, fluxes, and net reaction rates calculated from the measured profiles are used to test postulated reaction mechanisms. Particular objectives are to identify and to determine or confirm rate constants for the main benzene oxidation reactions in flames, and to characterize fullerenes and their formation mechanisms and kinetics.

  7. Heat release and flame structure measurements of self-excited acoustically-driven premixed methane flames

    SciTech Connect (OSTI)

    Kopp-Vaughan, Kristin M.; Tuttle, Steven G.; Renfro, Michael W.; King, Galen B.

    2009-10-15

    An open-open organ pipe burner (Rijke tube) with a bluff-body ring was used to create a self-excited, acoustically-driven, premixed methane-air conical flame, with equivalence ratios ranging from 0.85 to 1.05. The feed tube velocities corresponded to Re = 1780-4450. Coupled oscillations in pressure, velocity, and heat release from the flame are naturally encouraged at resonant frequencies in the Rijke tube combustor. This coupling creates sustainable self-excited oscillations in flame front area and shape. The period of the oscillations occur at the resonant frequency of the combustion chamber when the flame is placed {proportional_to}1/4 of the distance from the bottom of the tube. In this investigation, the shape of these acoustically-driven flames is measured by employing both OH planar laser-induced fluorescence (PLIF) and chemiluminescence imaging and the images are correlated to simultaneously measured pressure in the combustor. Past research on acoustically perturbed flames has focused on qualitative flame area and heat release relationships under imposed velocity perturbations at imposed frequencies. This study reports quantitative empirical fits with respect to pressure or phase angle in a self-generated pressure oscillation. The OH-PLIF images were single temporal shots and the chemiluminescence images were phase averaged on chip, such that 15 exposures were used to create one image. Thus, both measurements were time resolved during the flame oscillation. Phase-resolved area and heat release variations throughout the pressure oscillation were computed. A relation between flame area and the phase angle before the pressure maximum was derived for all flames in order to quantitatively show that the Rayleigh criterion was satisfied in the combustor. Qualitative trends in oscillating flame area were found with respect to feed tube flow rates. A logarithmic relation was found between the RMS pressure and both the normalized average area and heat release rate for all flames. (author)

  8. Numerical and experimental studies of ethanol flames and autoignition theory for higher alkanes

    E-Print Network [OSTI]

    Saxena, Priyank

    2007-01-01

    of hydrogen and carbon monoxide”, Combustion and Flame, 145,of Hydrogen and Carbon Monoxide”, Combustion and Flame, 145,hydrogen and carbon monoxide”, Combustion and Flame , 145,

  9. The interaction of high-speed turbulence with flames: Turbulent flame speed

    SciTech Connect (OSTI)

    Poludnenko, A.Y.; Oran, E.S. [Laboratory for Computational Physics and Fluid Dynamics, Naval Research Laboratory, Washington, DC 20375 (United States)

    2011-02-15

    Direct numerical simulations of the interaction of a premixed flame with driven, subsonic, homogeneous, isotropic, Kolmogorov-type turbulence in an unconfined system are used to study the mechanisms determining the turbulent flame speed, S{sub T}, in the thin reaction zone regime. High intensity turbulence is considered with the r.m.s. velocity 35 times the laminar flame speed, S{sub L}, resulting in the Damkoehler number Da=0.05. The simulations were performed with Athena-RFX, a massively parallel, fully compressible, high-order, dimensionally unsplit, reactive-flow code. A simplified reaction-diffusion model, based on the one-step Arrhenius kinetics, represents a stoichiometric H{sub 2}-air mixture under the assumption of the Lewis number Le=1. Global properties and the internal structure of the flame were analyzed in an earlier paper, which showed that this system represents turbulent combustion in the thin reaction zone regime. This paper demonstrates that: (1) The flame brush has a complex internal structure, in which the isosurfaces of higher fuel mass fractions are folded on progressively smaller scales. (2) Global properties of the turbulent flame are best represented by the structure of the region of peak reaction rate, which defines the flame surface. (3) In the thin reaction zone regime, S{sub T} is predominantly determined by the increase of the flame surface area, A{sub T}, caused by turbulence. (4) The observed increase of S{sub T} relative to S{sub L} exceeds the corresponding increase of A{sub T} relative to the surface area of the planar laminar flame, on average, by {approx}14%, varying from only a few percent to as high as {approx}30%. (5) This exaggerated response is the result of tight flame packing by turbulence, which causes frequent flame collisions and formation of regions of high flame curvature >or similar 1/{delta}{sub L}, or ''cusps,'' where {delta}{sub L} is the thermal width of the laminar flame. (6) The local flame speed in the cusps substantially exceeds its laminar value, which results in a disproportionately large contribution of cusps to S{sub T} compared with the flame surface area in them. (7) A criterion is established for transition to the regime significantly influenced by cusp formation. In particular, at Karlovitz numbers Ka >or similar 20, flame collisions provide an important mechanism controlling S{sub T}, in addition to the increase of A{sub T} by large-scale motions and the potential enhancement of diffusive transport by small-scale turbulence. (author)

  10. Flame Spectral Analysis for Boiler Control 

    E-Print Network [OSTI]

    Metcalfe, C. I.; Cole, W. E.; Batra, S. K.

    1987-01-01

    range from the flames and using these measurements to determine the burner operating conditions. Two prototype instruments have been installed on package boilers at a Con Edison powerplant and Polaroid facility, and their performance has been evaluated...

  11. Enol Intermediates Unexpectedly Found in Flames

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    at ALS Chemical Dynamics Beamline 9.0.2. In the apparatus, premixed reagent gases enter the flame chamber through the porous flat face of a burner that translates...

  12. Environmentally Benign Flame Retardant Nanocoatings for Fabric 

    E-Print Network [OSTI]

    Li, Yu-Chin

    2012-07-16

    A variety of materials were used to fabricate nanocoatings using layer-by-layer (LbL) assembly to reduce the flammability of cotton fabric. The most effective brominated flame retardants have raised concerns related to ...

  13. NO concentration imaging in turbulent nonpremixed flames

    SciTech Connect (OSTI)

    Schefer, R.W. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    The importance of NO as a pollutant species is well known. An understanding of the formation characteristics of NO in turbulent hydrocarbon flames is important to both the desired reduction of pollutant emissions and the validation of proposed models for turbulent reacting flows. Of particular interest is the relationship between NO formation and the local flame zone, in which the fuel is oxidized and primary heat release occurs. Planar imaging of NO provides the multipoint statistics needed to relate NO formation to the both the flame zone and the local turbulence characteristics. Planar imaging of NO has been demonstrated in turbulent flames where NO was seeded into the flow at high concentrations (2000 ppm) to determine the gas temperature distribution. The NO concentrations in these experiments were significantly higher than those expected in typical hydrocarbon-air flames, which require a much lower detectability limit for NO measurements. An imaging technique based on laser-induced fluorescence with sufficient sensitivity to study the NO formation mechanism in the stabilization region of turbulent lifted-jet methane flames.

  14. Characterisation of an oxy-coal flame through digital imaging

    SciTech Connect (OSTI)

    Smart, John; Riley, Gerry [RWE npower plc, Windmill Hill Business Park, Whitehill Way, Swindon SN5 6PB (United Kingdom); Lu, Gang; Yan, Yong [Instrumentation, Control and Embedded Systems Research Group, School of Engineering and Digital Arts, University of Kent, Canterbury, Kent CT2 7NT (United Kingdom)

    2010-06-15

    This paper presents investigations into the impact of oxy-fuel combustion on flame characteristics through the application of digital imaging and image processing techniques. The characteristic parameters of the flame are derived from flame images that are captured using a vision-based flame monitoring system. Experiments were carried out on a 0.5 MW{sub th} coal combustion test facility. Different flue gas recycle ratios and furnace oxygen levels were created for two different coals. The characteristics of the flame and the correlation between the measured flame parameters and corresponding combustion conditions are described and discussed. The results show that the flame temperature decreases with the recycle ratio for both test coals, suggesting that the flame temperature is effectively controlled by the flue gas recycle ratio. The presence of high levels of CO{sub 2} at high flue gas recycle ratios may result in delayed combustion and thus has a detrimental effect on the flame stability. (author)

  15. Redox Shuttle Additives | Argonne National Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration wouldMassR&D100 Winners * Impactsand engineersAcquisition andRedox ShuttleRedox Shuttle

  16. Laminar flame speeds of moist syngas mixtures

    SciTech Connect (OSTI)

    Das, Apurba K. [Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH 44106 (United States); Kumar, Kamal; Sung, Chih-Jen [Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269 (United States)

    2011-02-15

    This work experimentally investigates the effect of the presence of water vapor on the laminar flame speeds of moist syngas/air mixtures using the counterflow twin-flame configuration. The experimental results presented here are for fuel lean syngas mixtures with molar percentage of hydrogen in the hydrogen and carbon monoxide mixture varying from 5% to 100%, for an unburned mixture temperature of 323 K, and under atmospheric pressure. At a given equivalence ratio, the effect of varying amount of water vapor addition on the measured laminar flame speed is demonstrated. The experimental laminar flame speeds are also compared with computed values using chemical kinetic mechanisms reported in the literature. It is found that laminar flame speed varies non-monotonically with addition of water for the carbon monoxide rich mixtures. It first increases with increasing amount of water addition, reaches a maximum value, and then decreases. An integrated reaction path analysis is further conducted to understand the controlling mechanism responsible for the non-monotonic variation in laminar flame speed due to water addition. On the other hand, for higher values of H{sub 2}/CO ratio the laminar flame speed monotonically decreases with increasing water addition. It is shown that the competition between the chemical and thermal effects of water addition leads to the observed response. Furthermore, reaction rate sensitivity analysis as well as binary diffusion coefficient sensitivity analysis are conducted to identify the possible sources of discrepancy between the experimental and predicted values. The sensitivity results indicate that the reaction rate constant of H{sub 2}+OH = H{sub 2}O+H is worth revisiting and refinement of binary diffusion coefficient data of N{sub 2}-H{sub 2}O, N{sub 2}-H{sub 2}, and H{sub 2}-H{sub 2}O pairs can be considered. (author)

  17. Can we characterize turbulence in premixed flames?

    SciTech Connect (OSTI)

    Lipatnikov, A.N. [Department of Applied Mechanics, Chalmers University of Technology, Gothenburg, 412 96 (Sweden)

    2009-06-15

    Modeling of premixed turbulent combustion involves averaging reaction rates in turbulent flows. The focus of most approaches to resolving this problem has been placed on determining the dependence of the mean rate w of product creation on the laminar flame speed S{sub L}, the rms turbulence velocity u', etc. The goal of the present work is to draw attention to another issue: May the input quantity u{sup '} for a model of w= w(u'/S{sub L},..) be considered to be known? The point is that heat release substantially affects turbulence and, hence, turbulence characteristics in premixed flames should be modeled. However, standard moment methods for numerically simulating turbulent flows do not allow us to evaluate the true turbulence characteristics in a flame. For instance, the Reynolds stresses in premixed flames are affected not only by turbulence itself, but also by velocity jump across flamelets. A common way to resolving this problem consists of considering the Reynolds stresses conditioned on unburned (or burned) mixture to be the true turbulence characteristics. In the present paper, this widely accepted but never proved hypothesis is put into question, first, by considering simple model constant-density problems (flame motion in an oscillating one-dimensional laminar flow; flame stabilized in a periodic shear, one-dimensional, laminar flow; turbulent mixing). In all the cases, the magnitude of velocity fluctuations, calculated using the conditioned Reynolds stresses, is affected by the intermittency of reactants and products and, hence, is not the true rms velocity. Second, the above claim is further supported by comparing balance equations for the mean and conditioned Reynolds stresses. The conditioned Reynolds stresses do not characterize the true turbulence in flames, because conditional averaging cuts off flow regions characterized by either high or low velocities. (author)

  18. Space

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home RoomPreservation ofAlbuquerque|SensitiveApril 2, 2014 Smith Named as NewAprilSpace

  19. Physics Results From Alpha Magnetic Spectrometer 1998 Shuttle Flight

    E-Print Network [OSTI]

    Ming-Huey A. Huang

    2001-04-13

    The Alpha Magnetic Spectrometer (AMS) is a particle detector designed to detect antimatter. During the 10-day test flight on the space shuttle in June 1998, AMS detected $10^8$ events. Upon analysis, no antimatter was found and the antimatter limit was reduced to $1.1\\times10^{-6}$. The proton spectrum shows some differences with the cosmic ray flux used in atmospheric neutrino simulation. A large amount of protons, positrons, and electrons were found below the geomagnetic rigidity cutoff. The energy of these particles are as high as several GeV, one order of magnitude higher than any previously measured energy in radiation belts. These particles also exhibit many interesting features. This paper reviews the results in the four published papers of the AMS collaboration and provides explanation for some features of the albedo particles.

  20. Conditional analysis of lifted hydrogen jet diffusion flame experimental data and comparison to laminar flame solutions

    SciTech Connect (OSTI)

    Cheng, T.S. [Department of Mechanical Engineering, Chung Hua University, Hsinchu 300 (China); Wehrmeyer, J.A. [Aerospace Testing Alliance, Arnold Air Force Base, TN 37389 (United States); Pitz, R.W. [Department of Mechanical Engineering, Vanderbilt University, Nashville, TN 37235 (United States)

    2007-09-15

    Simultaneous point measurements of temperature, mixture fraction, major species, and OH concentrations in a lifted turbulent hydrogen jet flame are reprocessed to obtain the Favre average and conditional mean profiles. Large discrepancies between the Favre average and the ensemble average temperature, H{sub 2}O, and OH mole fractions are found at the lifted flame base, due to density weighting of fairly large samples of unreacted mixtures. Conditional statistics are used to reveal the reaction zone structure in mixture fraction coordinates. The cross-stream dependence of conditional reactive scalars, which is most notable at the lifted flame base and decreases to negligible levels with increasing streamwise positions, could be attributed to radial differences in both the Damkoehler number and the level of partial premixing. Conditional results indicate that the lifted flame is stabilized at the outer region of the jet characterized by low strain rates and lean mixtures. Comparison of the measured conditional mean OH vs H{sub 2}O with a series of stretched laminar partially premixed flame and diffusion flame calculations reveals that strong partial premixing takes place at the lifted flame base and the strain rates vary from a=14,000 to 100 s{sup -1}. The level of partial premixing and the strain rate decrease with increasing downstream locations. The range of estimated scalar dissipation rates ({chi}{approx}1-0.13 s{sup -1}) at a further downstream location (x/D=33.3) is in agreement with reported values and the flame composition reaches an equilibrium condition at x/D=194.4. These results combined with previously reported data provide a benchmark data set for evaluation and refinement of turbulent combustion models for lifted hydrogen jet flame predictions. (author)

  1. Pentan isomers compound flame front structure

    SciTech Connect (OSTI)

    Mansurov, Z.A.; Mironenko, A.W.; Bodikov, D.U.; Rachmetkaliev, K.N.

    1995-08-13

    The fuels (hexane, pentane, diethyl ether) and conditions investigated in this study are relevant to engine knock in spark- ignition engines. A review is provided of the field of low temperature hydrocarbon oxidation. Studies were made of radical and stable intermediate distribution in the front of cool flames: Maximum concentrations of H atoms and peroxy radicals were observed in the luminous zone of the cool flame front. Peroxy radicals appear before the luminous zone at 430 K due to diffusion. H atoms were found in cool flames of butane and hexane. H atoms diffuses from the luminous zone to the side of the fresh mixture, and they penetrate into the fresh mixture to a small depth. Extension of action sphear of peroxy radicals in the fresh mixture is much greater than that of H atoms due to their small activity and high concentrations.

  2. Investigations of swirl flames in a gas turbine model combustor

    SciTech Connect (OSTI)

    Meier, W.; Duan, X.R.; Weigand, P.

    2006-01-01

    The thermochemical states of three swirling CH{sub 4}/air diffusion flames, stabilized in a gas turbine model combustor, were investigated using laser Raman scattering. The flames were operated at different thermal powers and air/fuel ratios and exhibited different flame behavior with respect to flame instabilities. They had previously been characterized with respect to their flame structures, velocity fields, and mean values of temperature, major species concentrations, and mixture fraction. The single-pulse multispecies measurements presented in this article revealed very rapid mixing of fuel and air, accompanied by strong effects of turbulence-chemistry interactions in the form of local flame extinction and ignition delay. Flame stabilization is accomplished mainly by hot and relatively fuel-rich combustion products, which are transported back to the flame root within an inner recirculation zone. The flames are not attached to the fuel nozzle, and are stabilized approximately 10 mm above the fuel nozzle, where fuel and air are partially premixed before ignition. The mixing and reaction progress in this area are discussed in detail. The flames are short (<50 mm), especially that exhibiting thermoacoustic oscillations, and reach a thermochemical state close to adiabatic equilibrium at the flame tip. The main goals of this article are to outline results that yield deeper insight into the combustion of gas turbine flames and to establish an experimental database for the validation of numerical models.

  3. FLAME SURFACE DENSITIES IN PREMIXED COMBUSTION AT MEDIUM TO HIGH

    E-Print Network [OSTI]

    Gülder, Ömer L.

    FLAME SURFACE DENSITIES IN PREMIXED COMBUSTION AT MEDIUM TO HIGH TURBULENCE INTENSITIES O¨ MER L in turbulent premixed propane= air flames were determined experimentally. The instantaneous flame fronts were combustion regime as defined by the most recent turbulent premixed combustion dia- grams. From 100 to 800

  4. Flame front tracking by laser induced fluorescence spectroscopy and advanced

    E-Print Network [OSTI]

    Hamarneh, Ghassan

    surface characteristics in turbulent premixed propane/air combustion," Combustion and Flame 120(4), 407 References and links 1. J. Warnatz, U. Maas, and R.W. Dibble, Combustion - physical and chemical fundamentals, "Characterization of flame front surfaces in turbulent premixed methane/air combustion," Combustion and Flame 101

  5. DETAILED CHEMISTRY MODELING OF LAMINAR DIFFUSION FLAMES ON PARALLEL COMPUTERS

    E-Print Network [OSTI]

    . The gas­jet diffusion flame is the basic element of many combustion systems, such as gas turbines, ram­speed, three­dimensional, turbulent reacting systems, gas­jet laminar diffusion flames constitute a problem jets, and industrial furnaces. Furthermore, the fundamental understand­ ing of laminar diffusion flames

  6. Computatonal and experimental study of laminar flames

    SciTech Connect (OSTI)

    Smooke, M.D.; Long, M.B. [Yale Univ., New Haven, CT (United States)

    1993-12-01

    This research has centered on an investigation of the effects of complex chemistry and detailed transport on the structure and extinction of hydrocarbon flames in counterflow, cylindrical and coflowing axisymmetric configurations. The authors have pursued both computational and experimental aspects of the research in parallel. The computational work has focused on the application of accurate and efficient numerical methods for the solution of the one and two-dimensional nonlinear boundary value problems describing the various reacting systems. Detailed experimental measurements were performed on axisymmetric coflow flames using two-dimensional imaging techniques. In particular, spontaneous Raman scattering and laser induced fluorescence were used to measure the temperature, major and minor species profiles.

  7. Modeling Space Shuttle Software Failures at Varying Criticality Levels

    E-Print Network [OSTI]

    Morgan, Joseph

    of a software failure data set for an industrial software development project. They propose models based criticality levels. A family of models based on transforms of cumulative time and cumulative failures the exponential, logarithmic, and power models. It also includes models based on transforms of the time per

  8. Entropy Based Anomaly Detection Applied to Space Shuttle Main Engines

    E-Print Network [OSTI]

    Tumer, Kagan

    collections of sensor suites is vital to in- creasing safety and reducing maintenance costs of complex clustering approach revealed a fault in the high pressure fuel turbo-pump early in the test such as maintenance, whereas the in-flight data is crucial for range-safety operations and auto- mated abort attempts

  9. Antimatter Experiment Aboard Friday's Space Shuttle Launch | Department

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE: Alternative FuelsofProgram:Y-12 Beta-3AUDITLeslieAlgaeAnatomy of aoffor a Clean EnergyPlantof

  10. Rayleigh-Taylor Unstable Flames -- Fast or Faster?

    E-Print Network [OSTI]

    Hicks, E P

    2015-01-01

    Rayleigh-Taylor (RT) unstable flames play a key role in the explosions of Type Ia supernovae. However, the dynamics of these flames is still not well-understood. RT unstable flames are affected by both the RT instability of the flame front and by RT-generated turbulence. The coexistence of these factors complicates the choice of flame speed subgrid models for full-star Type Ia simulations. Both processes can stretch and wrinkle the flame surface, increasing its area and, therefore, the burning rate. In past research, subgrid models have been based on either the RT instability or turbulence setting the flame speed. We evaluate both models, checking their assumptions and their ability to correctly predict the turbulent flame speed. Specifically, we analyze a large parameter study of 3D direct numerical simulations of RT unstable model flames. This study varies both the simulation domain width and the gravity in order to probe a wide range of flame behaviors. We show that RT unstable flames are different from tr...

  11. Radiation Heat Transfer in Particle-Laden Gaseous Flame: Flame Acceleration and Triggering Detonation

    E-Print Network [OSTI]

    Liberman, M A; Kiverin, A D

    2015-01-01

    In this study we examine influence of the radiation heat transfer on the combustion regimes in the mixture, formed by suspension of fine inert particles in hydrogen gas. The gaseous phase is assumed to be transparent for the thermal radiation, while the radiant heat absorbed by the particles is then lost by conduction to the surrounding gas. The particles and gas ahead of the flame is assumed to be heated by radiation from the original flame. It is shown that the maximum temperature increase due to the radiation preheating becomes larger for a flame with lower velocity. For a flame with small enough velocity temperature of the radiation preheating may exceed the crossover temperature, so that the radiation heat transfer may become a dominant mechanism of the flame propagation. In the case of non-uniform distribution of particles, the temperature gradient formed due to the radiation preheating can initiate either deflagration or detonation ahead of the original flame via the Zel'dovich's gradient mechanism. Th...

  12. Power-law wrinkling turbulence-flame interaction model for astrophysical flames

    SciTech Connect (OSTI)

    Jackson, Aaron P.; Townsley, Dean M.; Calder, Alan C.

    2014-04-01

    We extend a model for turbulence-flame interactions (TFI) to consider astrophysical flames with a particular focus on combustion in Type Ia supernovae. The inertial range of the turbulent cascade is nearly always under-resolved in simulations of astrophysical flows, requiring the use of a model in order to quantify the effects of subgrid-scale wrinkling of the flame surface. We provide implementation details to extend a well-tested TFI model to low-Prandtl number flames for use in the compressible hydrodynamics code FLASH. A local, instantaneous measure of the turbulent velocity is calibrated for FLASH and verification tests are performed. Particular care is taken to consider the relation between the subgrid rms turbulent velocity and the turbulent flame speed, especially for high-intensity turbulence where the turbulent flame speed is not expected to scale with the turbulent velocity. Finally, we explore the impact of different TFI models in full-star, three-dimensional simulations of Type Ia supernovae.

  13. National Aeronautics and Space Administration www.nasa.gov

    E-Print Network [OSTI]

    Christian, Eric

    National Aeronautics and Space Administration www.nasa.gov Volume 3 Issue 10 August 2007 Space for Education and Discovery Pg 3 Goddard Space Scientists Earn Prestigious NASA Honors Pg 11 Space Shuttle and Discovery Pg 3 Goddard Space Scientists Earn Prestigious NASA Honors Pg 9 National Aeronautics and Space

  14. Excitation of thermoacoustic oscillations by small premixed flames

    SciTech Connect (OSTI)

    Coats, C.M.; Chang, Z.; Williams, P.D.

    2010-06-15

    Experiments have been carried out in which very small lean premixed flames closely representative of those formed by modern multiport domestic gas burners have been subjected to controlled acoustic perturbation. PLIF from CH has been used to visualise the flame response and the heat-release-rate fluctuations have been evaluated directly from the flame images. It is shown that small laminar flames can amplify the effects of acoustic velocity fluctuations by mechanisms that do not involve resonant heat loss to the burner and that the fluctuations in flame-front area are not adequately characterised by a Strouhal number alone. The measured transfer function is compared with the predictions of various analytical formulations and a new model of the flame oscillation is proposed which applies specifically to situations in which the design of the burner renders the flame base immobile. (author)

  15. AVTA: Idaho National Laboratory Experimental Hybrid Shuttle Bus Testing Results

    Broader source: Energy.gov [DOE]

    The following report describes testing results of the Idaho National Laboratory's demonstration hybrid shuttle bus. This research was conducted by Idaho National Laboratory.

  16. Spin-detection in a quantum electromechanical shuttle system

    E-Print Network [OSTI]

    J. Twamley; D. W. Utami; H. -S. Goan; G. J. Milburn

    2006-01-19

    We study the electrical transport of a harmonically-bound, single-molecule endohedral fullerene shuttle operating in the Coulomb blockade regime, i.e. single electron shuttling. In particular we examine the dependance of the tunnel current on an ultra-small stationary force exerted on the shuttle. We derive a quantum master equation for the full shuttle system which includes the metallic contacts, the spatially dependent tunnel couplings to the shuttle, the electronic and motional degrees of freedom of the shuttle itself and a coupling of the shuttle's motion to a phonon bath. We analyse the resulting quantum master equation and find that, due to the exponential dependance of the tunnel probability on the shuttle-contact separation, the current is highly sensitive to very small forces. In particular we predict that the spin state of the endohedral electrons of the endohedral fullerene in a large magnetic gradient field can be distinguished from the resulting current signals within a few tens of nanoseconds. This effect could prove useful for the detection of the endohedral spin-state of individual paramagnetic molecules such as N@C60 and P@C60, or the detection of very small static forces acting on a molecular shuttle.

  17. Sequencing and Scheduling in Coil Coating with Shuttles

    E-Print Network [OSTI]

    Mar 18, 2010 ... Sequencing and Scheduling in Coil Coating with Shuttles. Wiebke Höhn(hoehn * **at*** math.tu-berlin.de) Felix G. König(fkoenig ***at*** ...

  18. Flame quality monitor system for fixed firing rate oil burners

    DOE Patents [OSTI]

    Butcher, Thomas A. (Pt. Jefferson, NY); Cerniglia, Philip (Moriches, NY)

    1992-01-01

    A method and apparatus for determining and indicating the flame quality, or efficiency of the air-fuel ratio, in a fixed firing rate heating unit, such as an oil burning furnace, is provided. When the flame brightness falls outside a preset range, the flame quality, or excess air, has changed to the point that the unit should be serviced. The flame quality indicator output is in the form of lights mounted on the front of the unit. A green light indicates that the flame is about in the same condition as when the burner was last serviced. A red light indicates a flame which is either too rich or too lean, and that servicing of the burner is required. At the end of each firing cycle, the flame quality indicator goes into a hold mode which is in effect during the period that the burner remains off. A yellow or amber light indicates that the burner is in the hold mode. In this mode, the flame quality lights indicate the flame condition immediately before the burner turned off. Thus the unit can be viewed when it is off, and the flame condition at the end of the previous firing cycle can be observed.

  19. Redox shuttles for lithium ion batteries

    DOE Patents [OSTI]

    Weng, Wei; Zhang, Zhengcheng; Amine, Khalil

    2014-11-04

    Compounds may have general Formula IVA or IVB. ##STR00001## where, R.sup.8, R.sup.9, R.sup.10, and R.sup.11 are each independently selected from H, F, Cl, Br, CN, NO.sub.2, alkyl, haloalkyl, and alkoxy groups; X and Y are each independently O, S, N, or P; and Z' is a linkage between X and Y. Such compounds may be used as redox shuttles in electrolytes for use in electrochemical cells, batteries and electronic devices.

  20. Redox Shuttle Additives - Energy Innovation Portal

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration wouldMassR&D100 Winners * Impactsand engineersAcquisition andRedox Shuttle

  1. Alexandria Hilton Shuttle Schedule | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirleyEnergyTher i n c i p a l De p u t y A sCOLONYDepartmentand Staff EngagementHAMC Shuttle

  2. NOx Formation in a Premixed Syngas Flame

    SciTech Connect (OSTI)

    Yilmaz, S.L. (University of Pittsburgh, Pittsburgh, PA); Givi, P. (University of Pittsburgh, Pittsburgh, PA); Strakey, P.; Casleton, K.

    2006-11-01

    Reduction of NOx is a subject of significant current interest in stationary gas turbines. The objective of this study is to examine the effects of turbulence on non-thermal NOx formation in a syngas flame. This is archived by a detailed parametric study via PDF simulations of a partially stirred reactor and a dumped axisymmetric premixed flame. Several different detailed and reduced kinetics schemes are considered. The simulated results demonstrate the strong dependence of combustion process on turbulence. It is shown that the amount of NOx formation is significantly influenced by the inlet conditions. That is, the turbulence intensity can be tweaked to attain optimal ultra-low NOx emissions at a given temperature.

  3. Forcing of globally unstable jets and flames

    E-Print Network [OSTI]

    Li, Larry

    2012-04-10

    -performance combustion devices such as the gas turbine and the rocket engine3. Since that time, researchers from both academia and industry have been trying to discover the dominant physical mechanisms that govern how a flame responds to incident flow perturbations... the onset2 and saturation of thermoacoustic oscillations without costly and often prohibitive full-scale testing. In recent years, thermoacoustic instability has been a growing concern for de- velopers of gas turbines. New environmental legislations3 calling...

  4. The advanced flame quality indicator system

    SciTech Connect (OSTI)

    Oman, R.; Rossi, M.J.; Calia, V.S.; Davis, F.L.; Rudin, A. [Insight Technologies, Inc., Bohemia, NY (United States)

    1997-09-01

    By combining oil tank monitoring, systems diagnostics and flame quality monitoring in an affordable system that communicates directly with dealers by telephone modem, Insight Technologies offers new revenue opportunities and the capability for a new order of customer relations to oil dealers. With co-sponsorship from New York State Energy Research and Development Authority, we have incorporated several valuable functions to a new product based on the original Flame Quality Indicator concept licensed from the US DOE`s Brookhaven National Laboratory. The new system is the Advanced Flame Quality Indicator, or AFQI. As before, the AFQI monitors and reports the intensity of the burner flame relative to a calibration established when the burner is set up at AFQI installation. Repairs or adjustments are summoned by late-night outgoing telephone calls when limits are exceeded in either direction, indicating an impending contamination or other malfunction. A independently, a pressure transducer for monitoring oil tank level and filter condition, safety lockout alarms and a temperature monitor; all reporting automatically at instructed intervals via an on-board modem to a central station PC computer (CSC). Firmware on each AFQI unit and Insight-supplied software on the CSC automatically interact to maintain a customer database for an oil dealer, an OEM, or a regional service contractor. In addition to ensuring continuously clean and efficient operation, the AFQI offers the oil industry a new set of immediate payoffs, among which are reduced outages and emergency service calls, shorter service calls from cleaner operation, larger oil delivery drops, the opportunity to stretch service intervals to as along as three years in some cases, new selling features to keep and attract customers, and greatly enhanced customer contact, quality and reliability.

  5. Clothes That Care -- Flame Resistant Protection. 

    E-Print Network [OSTI]

    Kerbel, Claudia

    1980-01-01

    Concerns. Flame-resistant clothes are sometimes different than those made of traditional fabrics. Some consumer complain of allergic reactions , decreased durability, a less desir able feel or hand, shrinkage problems, wrinkling and increased cost.... To gain satisfaction from FR purchases, carefully examine clothing before buying. Read the care instructions , look for labels stating maximum shrinkage of one percent and report any allergic reactions or poor fabric performance to the retailer...

  6. Turbulent Nonpremixed Flames (TNF): Experimental Data Archives and Computational Submodels

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    In the 1990s an international collaboration formed around a series of workshops that became known collectively as the International Workshop on Measurement and Computation of Turbulent Non-Premixed Flames (TNF). An online library, hosted by Sandia National Laboratory (California) was established that provides data sets and submodels or "mechanisms" for the study of turbulence-chemistry interactions in turbulent nonpremixed and partially premixed combustion. Data are organized by flame types: simple jet flames, piloted jet flames, bluff body flames, and swirl flames. These data sets provide a means for collaborative comparisons of both measured and simulated/modeled research results and also assist scientists in determining priorities for further research. More than 20 data sets or databases are available from this website, along with various downloadable files of chemical mechanisms. The website also provides an extensive bibliography and the proceedings of the workshops themselves from 1996 through 2012. Information continues to be added to this collection.

  7. Reaction zone visualisation in swirling spray n-heptane flames

    E-Print Network [OSTI]

    Yuan, R.; Kariuki, J.; Dowlut, A.; Balachandran, R.; Mastorakos, E.

    2014-06-26

    = 5925 words Colloquium: Spray and droplet combustion (7) Alternative Colloquium: IC engine and Gas Turbine Combustion (11) Supplemental Material: no 2 Reaction zone visualisation in swirling spray n-heptane flames R. Yuan1,*, J... advanced turbulent combustion models. In gas turbines and industrial furnaces, the flame is virtually always stabilised by swirl. It can be argued that we know little about the fundamental processes of extinction of spray flames in recirculation zones...

  8. Soot precursor measurements in benzene and hexane diffusion flames

    SciTech Connect (OSTI)

    Kobayashi, Y.; Furuhata, T.; Amagai, K.; Arai, M.

    2008-08-15

    To clarify the mechanism of soot formation in diffusion flames of liquid fuels, measurements of soot and its precursors were carried out. Sooting diffusion flames formed by a small pool combustion equipment system were used for this purpose. Benzene and hexane were used as typical aromatic and paraffin fuels. A laser-induced fluorescence (LIF) method was used to obtain spatial distributions of polycyclic aromatic hydrocarbons (PAHs), which are considered as soot particles. Spatial distributions of soot in test flames were measured by a laser-induced incandescence (LII) method. Soot diameter was estimated from the temporal change of LII intensity. A region of transition from PAHs to soot was defined from the results of LIF and LII. Flame temperatures, PAH species, and soot diameters in this transition region were investigated for both benzene and hexane flames. The results show that though the flame structures of benzene and hexane were different, the temperature in the PAHs-soot transition region of the benzene flame was similar to that of the hexane flame. Furthermore, the relationship between the PAH concentrations measured by gas chromatography in both flames and the PAH distributions obtained from LIF are discussed. It was found that PAHs with smaller molecular mass, such as benzene and toluene, remained in both the PAHs-soot transition and sooting regions, and it is thought that molecules heavier than pyrene are the leading candidates for soot precursor formation. (author)

  9. Flame spread Analysis using a Variable B-Number

    E-Print Network [OSTI]

    Rangwala, Ali S.

    2006-01-01

    conducted. Radiative Heat transfer Radiation is identifiedE. M. Sparrow, Radiation Heat Transfer, Taylor & Francis (variation in heat transfer and flame radiation loss as as

  10. FIELD TEST OF THE FLAME QUALITY INDICATOR

    SciTech Connect (OSTI)

    Andrew M. Rudin; Thomas Butcher; Henry Troost

    2003-02-04

    The flame quality indicator concept was developed at BNL specifically to monitor the brightness of the flame in a small oil burner and to provide a ''call for service'' notification when the brightness has changed from its setpoint, either high or low. In prior development work BNL has explored the response of this system to operational upsets such as excess air changes, fouled atomizer nozzles, poor fuel quality, etc. Insight Technologies, Inc. and Honeywell, Inc. have licensed this technology from the U.S. Department of Energy and have been cooperating to develop product offerings which meet industry needs with an optimal combination of function and price. Honeywell has recently completed the development of the Flame Quality Monitor (FQM or Honeywell QS7100F). This is a small module which connects via a serial cable to the burners primary operating control. Primary advantages of this approach are simplicity, cost, and ease of installation. Call-for-service conditions are output in the form of front panel indicator lights and contact closure which can trigger a range of external communication options. Under this project a field test was conducted of the FQM in cooperation with service organizations in Virginia, Pennsylvania, New Jersey, New York, and Connecticut. At total of 83 field sites were included. At each site the FQM was installed in parallel with another embodiment of this concept--the Insight AFQI. The AFQI incorporates a modem and provides the ability to provide detailed information on the trends in the flame quality over the course of the two year test period. The test site population was comprised of 79.5% boilers, 13.7% warm air furnaces, and 6.8% water heaters. Nearly all were of residential size--with firing rates ranging from 0.6 gallons of oil per hour to 1.25. During the course of the test program the monitoring equipment successfully identified problems including: plugged fuel lines, fouled nozzles, collapsed combustion chambers, and poor fuel pump cut-off. Service organizations can use these early indications to reduce problems and service costs. There were also some ''call-for-service'' indications for which problems were not identified. The test program also showed that monitoring of the flame can provide information on burner run times and this can be used to estimate current oversize factors and to determine actual fuel usage, enabling more efficient fuel delivery procedures.

  11. Numerical and experimental studies of ethanol flames and autoignition theory for higher alkanes

    E-Print Network [OSTI]

    Saxena, Priyank

    2007-01-01

    studies of two-stage ethane-air flames”, Journal ofstudies of methane and ethane oxidation”, Combustion andstudies of two-stage ethane-air flames”, Journal of

  12. Nanotechnology finding its way into flame retardancy

    SciTech Connect (OSTI)

    Schartel, Bernhard, E-mail: bernhard.schartel@bam.de [BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205 Berlin (Germany)

    2014-05-15

    Nanotechnology is one of the key technologies of the 21{sup st} century. The exploitation of 'new' effects that arise from materials structured on the nano-scale has also been proposed successfully for flame retardancy of polymers since the end of the 90s. Of all of the approaches these include, at this time the use of nanocomposites offers the best potential for industrial application, also some other ideas are sketched, such as using electrospun nanofibers mats or layer-by-layer deposits as protection coatings, as well as sub-micrometer multilayer coatings as effective IR-mirrors. The general phenomena, inducing a flow limit in the pyrolysing melt and changing the fire residue, are identified in nanocomposites. Key experiments are performed such as quasi online investigation of the protection layer formation to understand what is going on in detail. The flame retardancy mechanisms are discussed and their impact on fire behaviour quantified. With the latter, the presentation pushes forward the state of the art. For instance, the heat shielding is experimentally quantified for a layered silicate epoxy resin nanocomposite proving that it is the only import mechanism controlling the reduction in peak heat release rate in the investigated system for different irradiations. The flame retardancy performance is assessed comprehensively illuminating not only the strengths but also the weak points of the concepts. Guidelines for materials development are deduced and discussed. Apart from inorganic fillers (layered silicate, boehmite, etc.) not only carbon nanoobjects such as multiwall carbon nanotubes, multilayer graphene and graphene are investigated, but also nanoparticles that are more reactive and harbor the potential for more beneficial interactions with the polymer matrix.

  13. Modeling of NOx formation in circular laminar jet flames 

    E-Print Network [OSTI]

    Siwatch, Vivek

    2007-04-25

    of air entrainment by jet depends upon the Sc number of fuel. The higher the Sc number, the higher is the air entrained which lowers the flame temperature and hence NOx formation. With increasing Sc number, flame volume increases which leads...

  14. Theory of High Frequency Acoustic Wave Scattering by Turbulent Flames

    E-Print Network [OSTI]

    Lieuwen, Timothy C.

    of the wave equation and assumes that the smallest scales of flame wrinkling are much larger than the acoustic the integral equation approach used in this paper to assess other characteristics of acoustic waveTheory of High Frequency Acoustic Wave Scattering by Turbulent Flames TIM LIEUWEN* School

  15. Flame Enhancement and Quenching in Fluid Flows Natalia Vladimirova

    E-Print Network [OSTI]

    Kiselev, Alex

    Flame Enhancement and Quenching in Fluid Flows Natalia Vladimirova , Peter Constantin , Alexander scale of the flow and laminar front thickness. For cellular flow, we obtain v U1/4 . We also study speed of the flame can be significantly altered by the fluid flow. Specifically, moderately intense

  16. Environmentally-benign Flame Retardant Nanocoating for Foam and Fabric 

    E-Print Network [OSTI]

    Cain, Amanda Ashley

    2014-12-09

    for the purpose of inhibiting or suppressing the combustion cycle. Inspiration for first applying polymer/clay thin films (i.e., nanobrick walls) as flame retardant (FR) coatings to polyurethane foam via LbL came from the final stage of a proposed flame...

  17. Kinetic Modeling of Counterflow Diffusion Flames of Butadiene

    E-Print Network [OSTI]

    Senkan, Selim M.

    Kinetic Modeling of Counterflow Diffusion Flames of Butadiene SILVIA GRANATA, TIZIANO FARAVELLI structures of counterflow diffusion and fuel-rich premixed 1,3-butadiene flames, to better understand the need for improved models and also the opportunity of new experiments of butadiene oxidation

  18. Flame Propagation in Poiseuille Flow under Adiabatic and M. MATALON*

    E-Print Network [OSTI]

    Sidorov, Nikita

    and and different distinguished regimes are described. From the results, simple criteria for flame flashback, which may be induced by the flame itself. Flashback conditions are not desirable for design purpose and are serious safety hazard. Therefore, it is important to determine the conditions under which flashback

  19. Transition from cool flame to thermal flame in compression ignition process

    SciTech Connect (OSTI)

    Yamada, Hiroyuki; Suzaki, Kotaro; Goto, Yuichi; Tezaki, Atsumu

    2008-07-15

    The mechanism that initiates thermal flames in compression ignition has been studied. Experimentally, a homogeneous charge compression ignition (HCCI) engine was used with DME, n-heptane, and n-decane. Arrhenius plots of the heat release rate in the HCCI experiments showed that rates of heat release with DME, n-heptane, and n-decane exhibited a certain activation energy that is identical to that of the H{sub 2}O{sub 2} decomposition reaction. The same feature was observed in diesel engine operation using ordinary diesel fuel with advanced ignition timing to make ignition occur after the end of fuel injection. These experimental results were reproduced in nondimensional simulations using kinetic mechanisms for DME, n-heptane, and n-decane, the last being developed by extending the n-heptane mechanism. Methanol addition, which suppresses low-temperature oxidation (LTO) and delays the ignition timing, had no effect on the activation energy obtained from the Arrhenius plot of heat release rate. Nevertheless, methanol addition lowered the heat release rates during the prethermal flame process. This is because H{sub 2}O{sub 2} formation during cool flame was reduced by adding methanol. The mechanism during the transition process from cool flame to thermal flame can be explained quantitatively using thermal explosion theory, in which the rate-determining reaction is H{sub 2}O{sub 2} decomposition, assuming that heat release in this period is caused by partial oxidation of DME and HCHO initiated with the reaction with OH produced though H{sub 2}O{sub 2} decomposition. (author)

  20. Lean Flame Stabilization Ring - Energy Innovation Portal

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACTThousand CubicResourcelogo and-E C H N I C A L TA LUsAboutLean Flame

  1. Investigations of swirl flames in a gas turbine model combustor

    SciTech Connect (OSTI)

    Weigand, P.; Meier, W.; Duan, X.R.; Stricker, W.; Aigner, M.

    2006-01-01

    A gas turbine model combustor for swirling CH{sub 4}/air diffusion flames at atmospheric pressure with good optical access for detailed laser measurements is discussed. Three flames with thermal powers between 7.6 and 34.9 kW and overall equivalence ratios between 0.55 and 0.75 were investigated. These behave differently with respect to combustion instabilities: Flame A burned stably, flame B exhibited pronounced thermoacoustic oscillations, and flame C, operated near the lean extinction limit, was subject to sudden liftoff with partial extinction and reanchoring. One aim of the studies was a detailed experimental characterization of flame behavior to better understand the underlying physical and chemical processes leading to instabilities. The second goal of the work was the establishment of a comprehensive database that can be used for validation and improvement of numerical combustion models. The flow field was measured by laser Doppler velocimetry, the flame structures were visualized by planar laser-induced fluorescence (PLIF) of OH and CH radicals, and the major species concentrations, temperature, and mixture fraction were determined by laser Raman scattering. The flow fields of the three flames were quite similar, with high velocities in the region of the injected gases, a pronounced inner recirculation zone, and an outer recirculation zone with low velocities. The flames were not attached to the fuel nozzle and thus were partially premixed before ignition. The near field of the flames was characterized by fast mixing and considerable finite-rate chemistry effects. CH PLIF images revealed that the reaction zones were thin (=<0.5 mm) and strongly corrugated and that the flame zones were short (h=<50 mm). Despite the similar flow fields of the three flames, the oscillating flame B was flatter and opened more widely than the others. In the current article, the flow field, structures, and mean and rms values of the temperature, mixture fraction, and species concentrations are discussed. Turbulence intensities, mixing, heat release, and reaction progress are addressed. In a second article, the turbulence-chemistry interactions in the three flames are treated.

  2. Trapping and aerogelation of nanoparticles in negative gravity hydrocarbon flames

    SciTech Connect (OSTI)

    Chakrabarty, Rajan K.; Novosselov, Igor V.; Beres, Nicholas D.; Moosmüller, Hans; Sorensen, Christopher M.; Stipe, Christopher B.

    2014-06-16

    We report the experimental realization of continuous carbon aerogel production using a flame aerosol reactor by operating it in negative gravity (?g; up-side-down configuration). Buoyancy opposes the fuel and air flow forces in ?g, which eliminates convectional outflow of nanoparticles from the flame and traps them in a distinctive non-tipping, flicker-free, cylindrical flame body, where they grow to millimeter-size aerogel particles and gravitationally fall out. Computational fluid dynamics simulations show that a closed-loop recirculation zone is set up in ?g flames, which reduces the time to gel for nanoparticles by ?10{sup 6}?s, compared to positive gravity (upward rising) flames. Our results open up new possibilities of one-step gas-phase synthesis of a wide variety of aerogels on an industrial scale.

  3. National Aeronautics and Space Administration space launch system

    E-Print Network [OSTI]

    Waliser, Duane E.

    Shuttle Main Engine Processing Facility, solid rocket motor test firing, J-2X test firing #12;Providing Heavy-Lift Launch Vehicle NASA's Space Launch System is an advanced, heavy-lift launch vehicle which including near-Earth asteroids, Lagrange points, the moon and ultimately Mars. The SLS heavy-lift launch

  4. National Aeronautics and Space Administration

    E-Print Network [OSTI]

    Rathbun, Julie A.

    -generation space fleet, Orion will push the envelope of human spaceflight far beyond low Earth orbit. Orion may features dozens of technology advancements and innovations that have been incorporated into the spacecraft and avionics systems. Building upon the best of Apollo and shuttle-era design, the Orion spacecraft includes

  5. Shuttling of ions for characterization of a microfabricated ion trap

    E-Print Network [OSTI]

    Fisher, Zachary (Zachary Kenneth)

    2012-01-01

    In this thesis, I present experimental results demonstrating the characterization of a planar Paul trap. I discuss the theory of ion trapping and analyze the voltages required for shuttling. Next, the characteristics of a ...

  6. DIMETHYL ETHER (DME)-FUELED SHUTTLE BUS DEMONSTRATION PROJECT

    SciTech Connect (OSTI)

    Elana M. Chapman; Shirish Bhide; Jennifer Stefanik; Howard Glunt; Andre L. Boehman; Allen Homan; David Klinikowski

    2003-04-01

    The objectives of this research and demonstration program are to convert a campus shuttle bus to operation on dimethyl ether, a potential ultra-clean alternative diesel fuel. To accomplish this objective, this project includes laboratory evaluation of a fuel conversion strategy, as well as, field demonstration of the DME-fueled shuttle bus. Since DME is a fuel with no lubricity (i.e., it does not possess the lubricating quality of diesel fuel), conventional fuel delivery and fuel injection systems are not compatible with dimethylether. Therefore, to operate a diesel engine on DME one must develop a fuel-tolerant injection system, or find a way to provide the necessary lubricity to the DME. In this project, they have chosen the latter strategy in order to achieve the objective with minimal need to modify the engine. The strategy is to blend DME with diesel fuel, to obtain the necessary lubricity to protect the fuel injection system and to achieve low emissions. The bulk of the efforts over the past year were focused on the conversion of the campus shuttle bus. This process, started in August 2001, took until April 2002 to complete. The process culminated in an event to celebrate the launching of the shuttle bus on DME-diesel operation on April 19, 2002. The design of the system on the shuttle bus was patterned after the system developed in the engine laboratory, but also was subjected to a rigorous failure modes effects analysis with help from Dr. James Hansel of Air Products. The result of this FMEA was the addition of layers of redundancy and over-pressure protection to the system on the shuttle bus. The system became operation in February 2002. Preliminary emissions tests and basic operation of the shuttle bus took place at the Pennsylvania Transportation institute's test track facility near the University Park airport. After modification and optimization of the system on the bus, operation on the campus shuttle route began in early June 2002. However, the work and challenges have continued as it has been difficult to maintain operability of the shuttle bus due to fuel and component difficulties. As of late June 2002, it appears that the pump head itself developed operational problems (loss of smooth function) leading to excessive stress on the magnetic coupling and excessive current draw to operate. A new pump head is being installed on the system to alleviate this problem and get the shuttle bus back in operation. In summary, the conversion is completed but there have been operational challenges in the field. They continue to work to make the shuttle bus as reliable to operate on DME-diesel blends as possible.

  7. Asymptotic Analysis of the Structure of Moderately Rich Methane-Air Flames

    E-Print Network [OSTI]

    Pitsch, Heinz

    Asymptotic Analysis of the Structure of Moderately Rich Methane-Air Flames K. SESHADRI,* X. S. BAI Republic of Germany The asymptotic structure of laminar, moderately rich, premixed methane flames structure of laminar, stoichi- ometric, and lean methane flames [1­6]. For rich flames, these analyses did

  8. Three-dimensional Numerical Simulations of Rayleigh-Taylor Unstable Flames in Type Ia Supernovae

    E-Print Network [OSTI]

    Bell, John B.

    ) instability and turbulence in accelerating a thermonuclear flame in Type Ia supernovae (SNe Ia) is well

  9. Turbulence-Flame Interactions in Type Ia Supernovae A. J. Aspden1

    E-Print Network [OSTI]

    Bell, John B.

    . INTRODUCTION The complex small-scale dynamics of turbulent thermonuclear flames are essential to understanding

  10. Step-By-Step Procedure on how to Request Advertisements in UH Shuttles 1. REVIEW POLICY -Read the Shuttle Bus Advertising Program policy available online

    E-Print Network [OSTI]

    Glasser, Adrian

    Step-By-Step Procedure on how to Request Advertisements in UH Shuttles 1. REVIEW POLICY - Read the Shuttle Bus Advertising Program policy available online http://www.uh.edu/pts/pdfs/UHShuttleAdvertisingPolicy.pdf 2. COMPLETE APPLICATION - Complete the Request for UH Shuttle Advertising application available

  11. Counterflow diffusion flame synthesis of ceramic oxide powders

    DOE Patents [OSTI]

    Katz, J.L.; Miquel, P.F.

    1997-07-22

    Ceramic oxide powders and methods for their preparation are revealed. Ceramic oxide powders are obtained using a flame process whereby one or more precursors of ceramic oxides are introduced into a counterflow diffusion flame burner wherein the precursors are converted into ceramic oxide powders. The nature of the ceramic oxide powder produced is determined by process conditions. The morphology, particle size, and crystalline form of the ceramic oxide powders may be varied by the temperature of the flame, the precursor concentration ratio, the gas stream and the gas velocity. 24 figs.

  12. Counterflow diffusion flame synthesis of ceramic oxide powders

    DOE Patents [OSTI]

    Katz, Joseph L. (Baltimore, MD); Miquel, Philippe F. (Towson, MD)

    1997-01-01

    Ceramic oxide powders and methods for their preparation are revealed. Ceramic oxide powders are obtained using a flame process whereby one or more precursors of ceramic oxides are introduced into a counterflow diffusion flame burner wherein the precursors are converted into ceramic oxide powders. The nature of the ceramic oxide powder produced is determined by process conditions. The morphology, particle size, and crystalline form of the ceramic oxide powders may be varied by the temperature of the flame, the precursor concentration ratio, the gas stream and the gas velocity.

  13. Turbulent Flame Propagation Characteristics of High Hydrogen Content Fuels

    SciTech Connect (OSTI)

    Seitzman, Jerry; Lieuwen, Timothy

    2014-09-30

    This final report describes the results of an effort to better understand turbulent flame propagation, especially at conditions relevant to gas turbines employing fuels with syngas or hydrogen mixtures. Turbulent flame speeds were measured for a variety of hydrogen/carbon monoxide (H2/CO) and hydrogen/methane (H2/CH4) fuel mixtures with air as the oxidizer. The measurements include global consumption speeds (ST,GC) acquired in a turbulent jet flame at pressures of 1-10 atm and local displacement speeds (ST,LD) acquired in a low-swirl burner at atmospheric pressure. The results verify the importance of fuel composition in determining turbulent flame speeds. For example, different fuel-air mixtures having the same unstretched laminar flame speed (SL,0) but different fuel compositions resulted in significantly different ST,GC for the same turbulence levels (u'). This demonstrates the weakness of turbulent flame speed correlations based simply on u'/SL,0. The results were analyzed using a steady-steady leading points concept to explain the sensitivity of turbulent burning rates to fuel (and oxidizer) composition. Leading point theories suggest that the premixed turbulent flame speed is controlled by the flame front characteristics at the flame brush leading edge, or, in other words, by the flamelets that advance farthest into the unburned mixture (the so-called leading points). For negative Markstein length mixtures, this is assumed to be close to the maximum stretched laminar flame speed (SL,max) for the given fuel-oxidizer mixture. For the ST,GC measurements, the data at a given pressure were well-correlated with an SL,max scaling. However the variation with pressure was not captured, which may be due to non-quasi-steady effects that are not included in the current model. For the ST,LD data, the leading points model again faithfully captured the variation of turbulent flame speed over a wide range of fuel-compositions and turbulence intensities. These results provide evidence that the leading points model can provide useful predictions of turbulent flame speed over a wide range of operating conditions and flow geometries.

  14. System and method for optical monitoring of a combustion flame

    DOE Patents [OSTI]

    Brown, Dale M; Sandvik, Peter M; Fedison, Jeffrey B; Matocha, Kevin S; Johnson, Thomas E

    2006-09-26

    An optical spectrometer for combustion flame temperature determination includes at least two photodetectors positioned for receiving light from a combustion flame, each of the at least two photodetectors having a different, overlapping bandwidth for detecting a respective output signal in an ultraviolet emission band; and a computer for subtracting a respective output signal of a first one of the at least two photodetectors from a respective output signal of a second one of the at least two photodetectors to obtain a segment signal, and using the segment signal to determine the combustion flame temperature.

  15. Extinction and structure of counterflow premixed flames. Master's thesis

    SciTech Connect (OSTI)

    Crump, J.K.

    1989-01-01

    A theoretical and experimental investigation of the extinction of a counterflow premixed flame was performed using methane as the fuel. The extinction limits were measured for a premixed flame stabilized between a premixed, fuel lean stream of methane, air and nitrogen and a stream of hot combustion product. The composition of the reactant mixture as a function of the strain rate was measured at extinction over a wide range of conditions. The results are interpreted using previously developed theories to derive overall chemical kinetic rate parameters. Temperature and composition profiles were obtained for several premixed flames near extinction.

  16. Response of flame thickness and propagation speed under intense turbulence in spatially developing lean premixed methane–air jet flames

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Sankaran, Ramanan; Hawkes, Evatt R.; Yoo, Chun Sang; Chen, Jacqueline H.

    2015-06-22

    Direct numerical simulations of three-dimensional spatially-developing turbulent Bunsen flames were performed at three different turbulence intensities. We performed these simulations using a reduced methane–air chemical mechanism which was specifically tailored for the lean premixed conditions simulated here. A planar-jet turbulent Bunsen flame configuration was used in which turbulent preheated methane–air mixture at 0.7 equivalence ratio issued through a central jet and was surrounded by a hot laminar coflow of burned products. The turbulence characteristics at the jet inflow were selected such that combustion occured in the thin reaction zones (TRZ) regime. At the lowest turbulence intensity, the conditions fall onmore »the boundary between the TRZ regime and the corrugated flamelet regime, and progressively moved further into the TRZ regime by increasing the turbulent intensity. The data from the three simulations was analyzed to understand the effect of turbulent stirring on the flame structure and thickness. Furthermore, statistical analysis of the data showed that the thermal preheat layer of the flame was thickened due to the action of turbulence, but the reaction zone was not significantly affected. A global and local analysis of the burning velocity of the flame was performed to compare the different flames. Detailed statistical averages of the flame speed were also obtained to study the spatial dependence of displacement speed and its correlation to strain rate and curvature.« less

  17. Response of flame thickness and propagation speed under intense turbulence in spatially developing lean premixed methane air jet flames

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Sankaran, Ramanan; Hawkes, Evatt R.; Yoo, Chun Sang; Chen, Jacqueline H.

    2015-06-22

    Direct numerical simulations of three-dimensional spatially-developing turbulent Bunsen flames were performed at three different turbulence intensities. We performed these simulations using a reduced methane–air chemical mechanism which was specifically tailored for the lean premixed conditions simulated here. A planar-jet turbulent Bunsen flame configuration was used in which turbulent preheated methane–air mixture at 0.7 equivalence ratio issued through a central jet and was surrounded by a hot laminar coflow of burned products. The turbulence characteristics at the jet inflow were selected such that combustion occured in the thin reaction zones (TRZ) regime. At the lowest turbulence intensity, the conditions fall onmore »the boundary between the TRZ regime and the corrugated flamelet regime, and progressively moved further into the TRZ regime by increasing the turbulent intensity. The data from the three simulations was analyzed to understand the effect of turbulent stirring on the flame structure and thickness. Furthermore, statistical analysis of the data showed that the thermal preheat layer of the flame was thickened due to the action of turbulence, but the reaction zone was not significantly affected. A global and local analysis of the burning velocity of the flame was performed to compare the different flames. Detailed statistical averages of the flame speed were also obtained to study the spatial dependence of displacement speed and its correlation to strain rate and curvature.« less

  18. Probing flame chemistry with MBMS, theory, and modeling

    SciTech Connect (OSTI)

    Westmoreland, P.R. [Univ. of Massachusetts, Amherst (United States)

    1993-12-01

    The objective is to establish kinetics of combustion and molecular-weight growth in C{sub 3} hydrocarbon flames as part of an ongoing study of flame chemistry. Specific reactions being studied are (1) the growth reactions of C{sub 3}H{sub 5} and C{sub 3}H{sub 3} with themselves and with unsaturated hydrocarbons and (2) the oxidation reactions of O and OH with C{sub 3}`s. This approach combines molecular-beam mass spectrometry (MBMS) experiments on low-pressure flat flames; theoretical predictions of rate constants by thermochemical kinetics, Bimolecular Quantum-RRK, RRKM, and master-equation theory; and whole-flame modeling using full mechanisms of elementary reactions.

  19. The effect of fuel composition on flame dynamics

    SciTech Connect (OSTI)

    Hendricks, Adam G.; Vandsburger, Uri

    2007-10-15

    As fuel sources diversify, the gas turbine industry is under increasing pressure to develop fuel-flexible plants, able to use fuels with a variety of compositions from a large range of sources. However, the dynamic characteristics vary considerably with composition, in many cases altering the thermoacoustic stability of the combustor. We compare the flame dynamics, or the response in heat release rate of the flame to acoustic perturbations, of the three major constituents of natural gas: methane, ethane, and propane. The heat release rate is quantified using OH* chemiluminescence and product gas temperature. Gas temperature is measured by tracking the absorption of two high-temperature water lines, via Tunable Diode Laser Absorption Spectroscopy. The flame dynamics of the three fuels differ significantly. The changes in flame dynamics due to variations in fuel composition have the potential to have a large effect on the thermoacoustic stability of the combustor. (author)

  20. Physics-based flame dynamics modeling and thermoacoustic instability mitigation

    E-Print Network [OSTI]

    Altay, Hurrem Murat

    2009-01-01

    The objectives of this work are (i) to investigate the coupled unsteady heat release mechanisms responsible for thermoacoustic instabilities under different flame anchoring configurations, (ii) to develop reduced-order ...

  1. Surface wettability studies of PDMS using flame plasma treatment

    E-Print Network [OSTI]

    Wang, Xin C

    2009-01-01

    The flame plasma treatment studied in this thesis was able to oxidize the surface of Polydimethylsiloxane (PDMS) in a fraction of a second. It was found to be a much faster way to modify PDMS surface wettability than the ...

  2. DIMETHYL ETHER (DME)-FUELED SHUTTLE BUS DEMONSTRATION PROJECT

    SciTech Connect (OSTI)

    Elana M. Chapman; Shirish Bhide; Jennifer Stefanik; Howard Glunt; Andre L. Boehman; Allen Homan; David Klinikowski

    2003-04-01

    The objectives of this research and demonstration program are to convert a campus shuttle bus to operation on dimethyl ether, a potential ultra-clean alternative diesel fuel. To accomplish this objective, this project includes laboratory evaluation of a fuel conversion strategy, as well as, field demonstration of the DME-fueled shuttle bus. Since DME is a fuel with no lubricity (i.e., it does not possess the lubricating quality of diesel fuel), conventional fuel delivery and fuel injection systems are not compatible with dimethyl ether. Therefore, to operate a diesel engine on DME one must develop a fuel-tolerant injection system, or find a way to provide the necessary lubricity to the DME. In this project, they have chosen the latter strategy in order to achieve the objective with minimal need to modify the engine. Their strategy is to blend DME with diesel fuel, to obtain the necessary lubricity to protect the fuel injection system and to achieve low emissions. The bulk of the efforts over the past year were focused on the conversion of the campus shuttle bus. This process, started in August 2001, took until April 2002 to complete. The process culminated in an event to celebrate the launching of the shuttle bus on DME-diesel operation on April 19, 2002. The design of the system on the shuttle bus was patterned after the system developed in the engine laboratory, but also was subjected to a rigorous failure modes effects analysis (FMEA, referred to by Air Products as a ''HAZOP'' analysis) with help from Dr. James Hansel of Air Products. The result of this FMEA was the addition of layers of redundancy and over-pressure protection to the system on the shuttle bus. The system became operational in February 2002. Preliminary emissions tests and basic operation of the shuttle bus took place at the Pennsylvania Transportation Institute's test track facility near the University Park airport. After modification and optimization of the system on the bus, operation on the campus shuttle route began in early June 2002. However, the work and challenges continued as it has been difficult to maintain operability of the shuttle bus due to fuel and component difficulties. In late June 2002, the pump head itself developed operational problems (loss of smooth function) leading to excessive stress on the magnetic coupling and excessive current draw to operate. A new pump head was installed on the system to alleviate this problem and the shuttle bus operated successfully on DME blends from 10-25 vol% on the shuttle bus loop until September 30, 2002. During the period of operation on the campus loop, the bus was pulled from service, operated at the PTI test track and real-time emissions measurements were obtained using an on-board emissions analyzer from Clean Air Technologies International, Inc. Particulate emissions reductions of 60% and 80% were observed at DME blend ratios of 12 vol.% and 25 vol.%, respectively, as the bus was operated over the Orange County driving cycle. Increases in NOx, CO and HC emissions were observed, however. In summary, the conversion of the shuttle bus was successfully accomplished, particulate emissions reductions were observed, but there were operational challenges in the field. Nonetheless, they were able to demonstrate reliable operation of the shuttle bus on DME-diesel blends.

  3. On the Evolution of Thermonuclear Flames on Large Scales

    E-Print Network [OSTI]

    Ju Zhang; O. E. Bronson Messer; Alexei M. Khokhlov; Tomasz Plewa

    2006-10-05

    The thermonuclear explosion of a massive white dwarf in a Type Ia supernova explosion is characterized by vastly disparate spatial and temporal scales. The extreme dynamic range inherent to the problem prevents the use of direct numerical simulation and forces modelers to resort to subgrid models to describe physical processes taking place on unresolved scales. We consider the evolution of a model thermonuclear flame in a constant gravitational field on a periodic domain. The gravitational acceleration is aligned with the overall direction of the flame propagation, making the flame surface subject to the Rayleigh-Taylor instability. The flame evolution is followed through an extended initial transient phase well into the steady-state regime. The properties of the evolution of flame surface are examined. We confirm the form of the governing equation of the evolution suggested by Khokhlov (1995). The mechanism of vorticity production and the interaction between vortices and the flame surface are discussed. The results of our investigation provide the bases for revising and extending previous subgrid-scale model.

  4. A comparative experimental and computational study of methanol, ethanol, and n-butanol flames

    SciTech Connect (OSTI)

    Veloo, Peter S.; Wang, Yang L.; Egolfopoulos, Fokion N.; Westbrook, Charles K.

    2010-10-15

    Laminar flame speeds and extinction strain rates of premixed methanol, ethanol, and n-butanol flames were determined experimentally in the counterflow configuration at atmospheric pressure and elevated unburned mixture temperatures. Additional measurements were conducted also to determine the laminar flame speeds of their n-alkane/air counterparts, namely methane, ethane, and n-butane in order to compare the effect of alkane and alcohol molecular structures on high-temperature flame kinetics. For both propagation and extinction experiments the flow velocities were determined using the digital particle image velocimetry method. Laminar flame speeds were derived through a non-linear extrapolation approach based on direct numerical simulations of the experiments. Two recently developed detailed kinetics models of n-butanol oxidation were used to simulate the experiments. The experimental results revealed that laminar flame speeds of ethanol/air and n-butanol/air flames are similar to those of their n-alkane/air counterparts, and that methane/air flames have consistently lower laminar flame speeds than methanol/air flames. The laminar flame speeds of methanol/air flames are considerably higher compared to both ethanol/air and n-butanol/air flames under fuel-rich conditions. Numerical simulations of n-butanol/air freely propagating flames, revealed discrepancies between the two kinetic models regarding the consumption pathways of n-butanol and its intermediates. (author)

  5. Redox shuttles for overcharge protection of lithium batteries

    DOE Patents [OSTI]

    Amine, Khalil (Downers Grove, IL); Chen, Zonghai (Downers Grove, IL); Wang, Qingzheng (San Jose, CA)

    2010-12-14

    The present invention is generally related to electrolytes containing novel redox shuttles for overcharge protection of lithium-ion batteries. The redox shuttles are capable of thousands hours of overcharge tolerance and have a redox potential at about 3-5.5 V vs. Li and particularly about 4.4-4.8 V vs. Li. Accordingly, in one aspect the invention provides electrolytes comprising an alkali metal salt; a polar aprotic solvent; and a redox shuttle additive that is an aromatic compound having at least one aromatic ring with four or more electronegative substituents, two or more oxygen atoms bonded to the aromatic ring, and no hydrogen atoms bonded to the aromatic ring; and wherein the electrolyte solution is substantially non-aqueous. Further there are provided electrochemical devices employing the electrolyte and methods of making the electrolyte.

  6. SuperShuttle CNG Fleet Start-Up Experience

    SciTech Connect (OSTI)

    Leslie Eudy.

    1999-05-18

    The Gas Research Institute (GRI) and the U.S. Department of Energy (DOE), along with several industry partners, are collaborating with SuperShuttle of Denver, Colorado, to evaluate natural gas vans added to the SuperShuttle fleet in 1999. Brand new (1999 model year) dedicated and bi-fuel compressed natural gas (CNG) vans manufactured by Ford Motor Company will be operated side-by-side with several similar gasoline vehicles in normal revenue service. Once the study is complete, DOE's National Renewable Energy Laboratory will analyze and compile the results for release.

  7. Soot particle size measurements in laminar premixed ethylene flames with laser-induced incandescence and scanning mobility particle sizer

    E-Print Network [OSTI]

    Yin, Chung-Yuan

    2009-01-01

    Size Measurements in Laminar Premixed Ethylene Flames withof soot aggregate sampled from a laminar acetyleneSize Measurements in Laminar Premixed Ethylene Flames with

  8. Nonlinear effects of stretch on the flame front propagation

    SciTech Connect (OSTI)

    Halter, F.; Tahtouh, T.; Mounaim-Rousselle, C. [Institut PRISME, Universite d'Orleans, 8 rue Leonard de Vinci, 45072 Orleans Cedex 2 (France)

    2010-10-15

    In all experimental configurations, the flames are affected by stretch (curvature and/or strain rate). To obtain the unstretched flame speed, independent of the experimental configuration, the measured flame speed needs to be corrected. Usually, a linear relationship linking the flame speed to stretch is used. However, this linear relation is the result of several assumptions, which may be incorrected. The present study aims at evaluating the error in the laminar burning speed evaluation induced by using the traditional linear methodology. Experiments were performed in a closed vessel at atmospheric pressure for two different mixtures: methane/air and iso-octane/air. The initial temperatures were respectively 300 K and 400 K for methane and iso-octane. Both methodologies (linear and nonlinear) are applied and results in terms of laminar speed and burned gas Markstein length are compared. Methane and iso-octane were chosen because they present opposite evolutions in their Markstein length when the equivalence ratio is increased. The error induced by the linear methodology is evaluated, taking the nonlinear methodology as the reference. It is observed that the use of the linear methodology starts to induce substantial errors after an equivalence ratio of 1.1 for methane/air mixtures and before an equivalence ratio of 1 for iso-octane/air mixtures. One solution to increase the accuracy of the linear methodology for these critical cases consists in reducing the number of points used in the linear methodology by increasing the initial flame radius used. (author)

  9. submitted to ApJ Direct Numerical Simulations of Type Ia Supernovae Flames I

    E-Print Network [OSTI]

    Bell, John B.

    for C/O thermonuclear flames at conditions relevant to the late stages of a Type Ia supernova explosion and results relevant for thermonuclear flames. Sivashinsky (1977) and Michelson & Sivashinsky (1977) studied

  10. Interactions between Soot and CH* in a Laminar Boundary Layer Type Diffusion Flame in Microgravity 

    E-Print Network [OSTI]

    Fuentes, Andres; Legros, Guillaume; Claverie, Alain; Joulain, Pierre; Vantelon, Jean-Pierre; Torero, Jose L

    A three-dimensional laminar non-buoyant diffusion flame was studied with the objective of improving the understanding of the soot production. The flame originated from a porous ethylene burner discharging into a laminar ...

  11. Turbulent Oxygen Flames in Type Ia Supernovae A. J. Aspden1

    E-Print Network [OSTI]

    Bell, John B.

    distance behind the carbon flame. However, for Da16 > 1, turbulence enhances heat transfer and drives layer, which we shall refer to as an oxygen "flame", is broadened and islands of nearly isothermal

  12. Numerical and experimental studies of ethanol flames and autoignition theory for higher alkanes

    E-Print Network [OSTI]

    Saxena, Priyank

    2007-01-01

    in methane-propane mixtures”, Combustion and Flame, 56,ethylene and propane mixtures”, Combustion and Flame, 117,propane mechanism are also tested. Finally, the additional steps related to acetaldehyde combustion

  13. HEXANE : architecting manned space exploration missions beyond low-earth orbit

    E-Print Network [OSTI]

    Rudat, Alexander August

    2013-01-01

    With the end of the Space Shuttle Program and the cancellation of the Constellation Program, NASA's long-term designs for manned spaceflight beyond Earth orbit remain indefinite. Although progress has been made in plans ...

  14. Direct Numerical Simulations of Type Ia Supernovae Flames II: The Rayleigh-Taylor Instability

    E-Print Network [OSTI]

    Bell, John B.

    Accelerating a thermonuclear flame to a large fraction of the speed of sound (possibly supersonic) is one

  15. A New Type of Steady and Stable, Laminar, Premixed Flame in Ultra-Lean, Hydrogen-Air Combustion

    SciTech Connect (OSTI)

    Grcar, Joseph F; Grcar, Joseph F

    2008-06-30

    Ultra-lean, hydrogen-air mixtures are found to support another kind of laminar flame that is steady and stable beside flat flames and flame balls. Direct numerical simulations are performed of flames that develop into steadily and stably propagating cells. These cells were the original meaning of the word"flamelet'' when they were observed in lean flammability studies conducted early in the development of combustion science. Several aspects of these two-dimensional flame cells are identified and are contrasted with the properties of one-dimensional flame balls and flat flames. Although lean hydrogen-air flames are subject to thermo-diffusive effects, in this case the result is to stabilize the flame rather than to render it unstable. The flame cells may be useful as basic components of engineering models for premixed combustion when the other types of idealized flames are inapplicable.

  16. Premixed Flame Dynamics in Narrow 2D Channels

    E-Print Network [OSTI]

    Ayoobi, Mohsen

    2015-01-01

    Premixed flames propagating within small channels show complex combustion phenomena that differ from flame propagation at conventional scales. Available experimental and numerical studies have documented stationary/non-stationary and/or asymmetric modes that depend on properties of the incoming reactant flow as well as channel geometry and wall temperatures. The present work seeks to illuminate mechanisms leading to symmetry-breaking and limit cycle behavior that are fundamental to these combustion modes. Specifically, four cases of lean premixed methane/air combustion -- two equivalence ratios (0.53 and 0.7) and two channel widths (2 and 5mm) -- are investigated in a 2D configuration with constant channel length and bulk inlet velocity, where numerical simulations are performed using detailed chemistry. External wall heating is simulated by imposing a linear temperature gradient as a boundary condition on both walls. In the 2mm-channel, both equivalence ratios produce flames that stabilize with symmetric fla...

  17. Gravity Effects on Steady Two-Dimensional Partially Premixed MethaneAir Flames

    E-Print Network [OSTI]

    Aggarwal, Suresh K.

    Gravity Effects on Steady Two-Dimensional Partially Premixed Methane­Air Flames ZHUANG SHU, CHUN W, University of Illinois at Chicago, Chicago, IL 60607-7022 Under normal-gravity conditions the flame heat is only weakly affected by gravity, the outer flame shows significant spatial differences for the two

  18. Phenomena in oscillating downward propagating flames induced by external laser irradiation method

    SciTech Connect (OSTI)

    Park, June Sung; Fujita, Osamu; Honko, Teruaki; Yamada, Yuichiro; Ito, Hiroyuki; Nakamura, Yuji [Division of Mechanical and Space Engineering, Hokkaido University, Kita13 Nishi8, Kita-ku, Sapporo, Hokkaido (Japan)

    2010-11-15

    Experiments in C{sub 2}H{sub 4}/CO{sub 2}-O{sub 2} premixed flames (Le < 1) propagating downwardly in a tube have been conducted to observe transition phenomena from laminar flame front to turbulent flame propagation triggered by external laser irradiation method. To investigate the exact motions of flame tip fluctuation at the initial moment of irradiating CO{sub 2} laser, the completely flat flame front is selected as a default flame, which is corresponding to the primary acoustic instability as reported by Searby (1992). According to the time-resolved observation, the flame front exposed to CO{sub 2} laser beam shows extremely unstable flame motions in which highly curved flame front towards unburned mixture is subject to diffusive-thermal instability. Then, the sudden enhanced burning state (increased flame surface) caused by flame instability induces the secondary acoustic instability which is akin to the observation in Ref. In the present study, we report the detailed descriptions of flame fronts on the transient behaviors leading the primary acoustic instability to turbulent motions actively induced by the absorption of externally irradiated CO{sub 2} laser beam. (author)

  19. A multi-level local defect correction technique for laminar flame simulation

    E-Print Network [OSTI]

    Eindhoven, Technische Universiteit

    A multi-level local defect correction technique for laminar flame simulation J.H.M. ten Thije to solve the low-Mach number approximation of the conservation laws for laminar flames. Elements of our, describing expansion of the gas mixture due to combustion. Boundary value problems for laminar flames

  20. A numerical study on the effects of pressure and gravity in laminar ethylene diffusion flames

    E-Print Network [OSTI]

    Gülder, Ömer L.

    A numerical study on the effects of pressure and gravity in laminar ethylene diffusion flames Marc 26 March 2011 Keywords: High-pressure Zero-gravity Laminar ethylene diffusion flames Soot modeling were studied numeri- cally in coflow ethylene­air laminar diffusion flames between 0.5 and 5 atm

  1. A comparison of computational and experimental lift-off heights of coflow laminar diffusion flames

    E-Print Network [OSTI]

    Long, Marshall B.

    A comparison of computational and experimental lift-off heights of coflow laminar diffusion flames*), and excited-state OH (denoted OH*) are imaged in coflow laminar diffusion flames. Measurements are made both was performed, which indicates that the lift-off height is sensitive to the laminar flame speed

  2. A numerical study on the effects of pressure and gravity in laminar ethylene diffusion flames

    E-Print Network [OSTI]

    Groth, Clinton P. T.

    A numerical study on the effects of pressure and gravity in laminar ethylene diffusion flames Marc xxxx Keywords: High-pressure Zero-gravity Laminar ethylene diffusion flames Soot modeling a b s t r a c in coflow ethylene­air laminar diffusion flames between 0.5 and 5 atm. Computations were per- formed

  3. Large-eddy simulation of lean hydrogenemethane turbulent premixed flames in the methane-

    E-Print Network [OSTI]

    Gülder, Ömer L.

    Large-eddy simulation of lean hydrogenemethane turbulent premixed flames in the methane- dominated to available experimental data. The enriched flame has 20% H2 in terms of mole fraction and lies in the methane methane flame in the methane- dominated regime. Copyright ª 2014, Hydrogen Energy Publications, LLC

  4. SOME OBSERVATIONS OF TWO-DIMENSIONAL SMOLDERING AND THE TRANSITION TO FLAMING

    E-Print Network [OSTI]

    Tse, Stephen D.

    process from slow smoldering to rapid flaming (fast, exothermic, gas-phase reactions) is also689 SOME OBSERVATIONS OF TWO-DIMENSIONAL SMOLDERING AND THE TRANSITION TO FLAMING Stephen D. Tse and the phenomenon of transition to flaming of a porous combustible material in the presence of an air

  5. NOx emissions in n-heptane/air partially premixed flames Hongshe Xue, Suresh K. Aggarwal*

    E-Print Network [OSTI]

    Aggarwal, Suresh K.

    NOx emissions in n-heptane/air partially premixed flames Hongshe Xue, Suresh K. Aggarwal; accepted 6 November 2002 Abstract NOx emissions in n-heptane/air partially premixed flames (PPFs) and equivalence ratio ( ) on NOx emissions are characterized for conditions in which the flame contains two

  6. Combustion and Flame 145 (2006) 324338 www.elsevier.com/locate/combustflame

    E-Print Network [OSTI]

    Gülder, Ömer L.

    2006-01-01

    . Guo et al. / Combustion and Flame 145 (2006) 324­338 325 for ethylene, propane, and butane counterflowCombustion and Flame 145 (2006) 324­338 www.elsevier.com/locate/combustflame Numerical study of The Combustion Institute. All rights reserved. Keywords: Soot; Laminar flame; Radiation; Hydrogen addition 1

  7. Flame Surface Fractal Characteristics in Premixed Turbulent Combustion at High Turbulence Intensities

    E-Print Network [OSTI]

    Gülder, Ömer L.

    Flame Surface Fractal Characteristics in Premixed Turbulent Combustion at High Turbulence of the flame surfaces in premixed turbulent combustion, the fractal approach is considered to be one with diameters of 11.2 and 22.4 mm, with flames of propane­air with equivalence ratios of 0.8 and 1

  8. LES/probability density function approach for the simulation of an ethanol spray flame

    E-Print Network [OSTI]

    Raman, Venkat

    LES/probability density function approach for the simulation of an ethanol spray flame Colin Heye a an experimental pilot-stabilized ethanol spray flame. In this particular flame, droplet evaporation occurs away: Large-eddy simulation; Probability density function; Flamelet/progress variable approach; Ethanol

  9. Prediction of oxy-coal flame stand-off using high-fidelity thermochemical models

    E-Print Network [OSTI]

    Prediction of oxy-coal flame stand-off using high-fidelity thermochemical models and the one Abstract An Eulerian one-dimensional turbulence (ODT) model is applied to simulate oxy-coal combustion temperature and mixing rate on oxy-coal flame is simulated and discussed where flame stand-off is used

  10. Spatially resolved heat release rate measurements in turbulent premixed flames

    SciTech Connect (OSTI)

    Ayoola, B.O.; Kaminski, C.F.; Balachandran, R.; Mastorakos, E.; Frank, J.H.

    2006-01-01

    Heat release rate is a fundamental property of great importance for the theoretical and experimental elucidation of unsteady flame behaviors such as combustion noise, combustion instabilities, and pulsed combustion. Investigations of such thermoacoustic interactions require a reliable indicator of heat release rate capable of resolving spatial structures in turbulent flames. Traditionally, heat release rate has been estimated via OH or CH radical chemiluminescence; however, chemiluminescence suffers from being a line-of-sight technique with limited capability for resolving small-scale structures. In this paper, we report spatially resolved two-dimensional measurements of a quantity closely related to heat release rate. The diagnostic technique uses simultaneous OH and CH{sub 2}O planar laser-induced fluorescence (PLIF), and the pixel-by-pixel product of the OH and CH{sub 2}O PLIF signals has previously been shown to correlate well with local heat release rates. Results from this diagnostic technique, which we refer to as heat release rate imaging (HR imaging), are compared with traditional OH chemiluminescence measurements in several flames. Studies were performed in lean premixed ethylene flames stabilized between opposed jets and with a bluff body. Correlations between bulk strain rates and local heat release rates were obtained and the effects of curvature on heat release rate were investigated. The results show that the heat release rate tends to increase with increasing negative curvature for the flames investigated for which Lewis numbers are greater than unity. This correlation becomes more pronounced as the flame gets closer to global extinction.

  11. Study of fuel-nitrogen reactions in rich, premixed flames

    SciTech Connect (OSTI)

    Roby, R.J.

    1988-01-01

    The formation and removal of nitrogen-containing species involved in fuel-nitrogen reactions have been studied in atmospheric-pressure fuel-rich hydrogen/oxygen/argon flames. The fuel-nitrogen reaction mechanism was investigated by addition of ammonia, nitric oxide, or hydrogen cyanide alone or with various hydrocarbons to a base flame. Profiles of stable nitrogen species and hydroxyl radical were measured in the post-flame gases. Results show that an initial rapid decay of nitric oxide added to a hydrogen/oxygen/argon flame to approximately 60% of its initial value occurs within 1.0 mm of the burner surface (0.5 msec). The primary reaction for removal of nitric oxide was found to be H + NO + M = HNO + M. The reaction of nitric oxide with various hydrocarbons to form hydrogen cyanide was found to be first order in both the initial hydrocarbon concentration and the initial nitric oxide concentration. A kinetic model was developed that only partially predicts the results obtained. Analysis showed that, by varying the heat of formation of imidogen within the limits of its uncertainty, agreement between the calculations and the data could be improved for nitric oxide and nitrogen. However, the amine, nitrous oxide and hydrogen cyanide profiles were found not to be significantly affected. The significant discrepancy between the measured and calculated ammonia profiles is discussed in terms of the model predictions of both the ammonia formation and decay rates. The reaction: NM + H = N + H/sub 2/ is identified as a key rate-controlling step for removal of amine species in these flames. Evidence from the data and theoretical calculations suggests that the rate of this reaction at the current flame conditions may be as much as a factor of ten slower than the previously reported value.

  12. Simulations of spray autoignition and flame establishment with two-dimensional CMC

    SciTech Connect (OSTI)

    Wright, Y.M.; Boulouchos, K. [Aerothermochemistry and Combustion Technology Laboratory, ETH Zurich (Switzerland); De Paola, G.; Mastorakos, E. [Hopkinson Laboratory, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ (United Kingdom)

    2005-12-01

    The unsteady two-dimensional conditional moment closure (CMC) model with first-order closure of the chemistry and supplied with standard models for the conditional convection and turbulent diffusion terms has been interfaced with a commercial engine CFD code and analyzed with two numerical methods, an 'exact' calculation with the method of lines and a faster fractional-step method. The aim was to examine the sensitivity of the predictions to the operator splitting errors and to identify the extent to which spatial transport terms are important for spray autoignition problems. Despite the underlying simplifications, solution of the full CMC equations allows a single model to be used for the autoignition, flame propagation ('premixed mode'), and diffusion flame mode of diesel combustion, which makes CMC a good candidate model for practical engine calculations. It was found that (i) the conditional averages have significant spatial gradients before ignition and during the premixed mode and (ii) that the inclusion of physical-space transport affects the calculation of the autoignition delay time, both of which suggest that volume-averaged CMC approaches may be inappropriate for diesel-like problems. A balance of terms in the CMC equation before and after autoignition shows the relative magnitude of spatial transport and allows conjectures on the structure of the premixed phase of diesel combustion. Very good agreement with available experimental data is found concerning ignition delays and the effect of background air turbulence on them.

  13. INVESTIGATION ON THE FLAME EXTINCTION LIMIT OF FUEL BLENDS

    SciTech Connect (OSTI)

    Ahsan R. Choudhuri

    2005-02-01

    Lean flame extinction limits of binary fuel mixtures of methane (CH{sub 4}), propane (C{sub 3}H{sub 8}), and ethane (C{sub 2}H{sub 6}) were measured using a twin-flame counter-flow burner. Experiments were conducted to generate an extinction equivalence ratio vs. global stretch rate plot and an extrapolation method was used to calculate the equivalence ratio corresponding to an experimentally unattainable zero-stretch condition. The foregoing gases were selected because they are the primary constitutes of natural gas, which is the primary focus of the present study. To validate the experimental setup and methodology, the flame extinction limit of pure fuels at zero stretch conditions were also estimated and compared with published values. The lean flame extinction limits of methane (f{sub ext} = 4.6%) and propane (f{sub ext} = 2.25%) flames measured in the present study agreed with the values reported in the literature. It was observed that the flame extinction limit of fuel blends have a polynomial relation with the concentration of component fuels in the mixture. This behavior contradicts with the commonly used linear Le Chatelier's approximation. The experimentally determined polynomial relations between the flame extinction limits of fuel blends (i.e. methane-propane and methane-ethane) and methane concentration are as follows: (1) Methane-Propane--%f{sub ext} = (1.05 x 10{sup -9}) f{sup 5}-(1.3644 x 10{sup -7}) f{sup 4}+(6.40299 x 10{sup -6}) f{sup 3}-(1.2108459 x 10{sup -4}) f{sup 2}+(2.87305329 x 10{sup -3}) f+2.2483; (2) Methane-Ethane--%f{sub ext} = (2.1 x 10{sup -9})f{sup 5}-(3.5752 x 10{sup -7}) f{sup 4}+(2.095425 x 10{sup -5}) f{sup 3}-(5.037353 x 10{sup -4}) f{sup 2} + 6.08980409 f + 2.8923. Where f{sub ext} is the extinction limits of methane-propane and methane-ethane fuel blends, and f is the concentration (% volume) of methane in the fuel mixture. The relations were obtained by fitting fifth order curve (polynomial regression) to experimentally measured extinction limits at different mixture conditions. To extend the study to a commercial fuel, the flame extinction limit for Birmingham natural gas (a blend of 95% methane, 5% ethane and 5% nitrogen) was experimentally determined and was found to be 3.62% fuel in the air-fuel mixture.

  14. Comparison of direct numerical simulation of lean premixed methane-air flames with strained laminar flame calculations.

    SciTech Connect (OSTI)

    Chen, Jacqueline H.; Hawkes, Evatt R.

    2004-08-01

    Direct numerical simulation (DNS) with complex chemistry was used to study statistics of displacement and consumption speeds in turbulent lean premixed methane-air flames. The main focus of the study is an evaluation of the extent to which a turbulent flame in the thin reaction zones regime can be described by an ensemble of strained laminar flames. Conditional averages with respect to strain for displacement and consumption speeds are presented over a wide range of strain typically encountered in a turbulent flame, compared with previous studies that either made local pointwise comparisons or conditioned the data on small strain and curvature. The conditional averages for positive strains are compared with calculated data from two different canonical strained laminar configurations to determine which is the optimal representation of a laminar flame structure embedded in a turbulent flame: the reactant-to-product (R-to-P) configuration or the symmetric twin flame configuration. Displacement speed statistics are compared for the progress-variable isosurface of maximum reaction rate and an isosurface toward the fresh gases, which are relevant for both modeling and interpretation of experiment results. Displacement speeds in the inner reaction layer are found to agree very well with the laminar R-to-P calculations over a wide range of strain for higher Damkhler number conditions, well beyond the regime in which agreement was expected. For lower Damkhler numbers, a reduced response to strain is observed, consistent with previous studies and theoretical expectations. Compared with the inner layer, broader and shifted probability density functions (PDFs) of displacement speed were observed in the fresh gases, and the agreement with the R-to-P calculations deteriorated. Consumption speeds show a poorer agreement with strained laminar calculations, which is attributed to multidimensional effects and a more attenuated unsteady response to strain fluctuations; however, they also show less departure from the unstrained laminar value, suggesting that detailed modeling of this quantity may not be critical for the conditions considered. For all quantities investigated, including CO production, the R-to-P laminar configuration provides an improved description relative to the twin flame configuration, which predicts qualitatively incorrect trends and overestimates extinction.

  15. Effects of gravity and pressure on laminar coflow methaneair diffusion flames at pressures from 1 to 60 atmospheres

    E-Print Network [OSTI]

    Gülder, Ömer L.

    Effects of gravity and pressure on laminar coflow methane­air diffusion flames at pressures from 1 characteristics and flame structure of coflow methane­air laminar diffusion flames between 1 and 60 atm were these effects through the numerical analysis of laminar diffusion flames at pressures ranging from 1 to 60 atm

  16. Single-electron shuttle based on a silicon quantum dot

    E-Print Network [OSTI]

    K. W. Chan; M. Mottonen; A. Kemppinen; N. S. Lai; K. Y. Tan; W. H. Lim; A. S. Dzurak

    2011-10-05

    We report on single-electron shuttling experiments with a silicon metal-oxide-semiconductor quantum dot at 300 mK. Our system consists of an accumulated electron layer at the Si/SiO_2 interface below an aluminum top gate with two additional barrier gates used to deplete the electron gas locally and to define a quantum dot. Directional single-electron shuttling from the source and to the drain lead is achieved by applying a dc source-drain bias while driving the barrier gates with an ac voltage of frequency f_p. Current plateaus at integer levels of ef_p are observed up to f_p = 240 MHz operation frequencies. The observed results are explained by a sequential tunneling model which suggests that the electron gas may be heated substantially by the ac driving voltage.

  17. AMS-Shuttle test for antimatter stars in our Galaxy

    E-Print Network [OSTI]

    K. M. Belotsky; Yu. A. Golubkov; M. Yu. Khlopov; R. V. Konoplich; S. G. Rubin; A. S. Sakharov

    1999-01-28

    The AMS--Shuttle experiment is shown to be sensitive to test the hypothesis on the existence of antimatter globular cluster in our Galaxy. The hypothesis follows from the analysis of possible tests for the mechanisms of baryosynthesis and uses antimatter domains in the matter dominated Universe as the probe for the physics underlying the origin of the matter. The total mass for the antimatter objects in our Galaxy is fixed from the below by the condition of antimatter domain survival in the matter dominated Universe and from above by the observed gamma ray flux. For this mass interval the expected fluxes of antinuclei can lead to up to ten antihelium events in the AMS-Shuttle experiment.

  18. Response of turbulent premixed flames to harmonic acoustic forcing

    E-Print Network [OSTI]

    Lieuwen, Timothy C.

    for land- based gas turbines, future aircraft engines, industrial heaters and boilers rely on premixed 1540 2006 The Combustion Institute. Published by Elsevier Inc. All rights reserved. Keywords: Flame area to a harmonic disturbance of given amplitude depends upon turbulence intensity. Low emissions combustion systems

  19. Preconditioned Multigrid Simulation of an Axisymmetric Laminar Diffusion Flame \\Lambda

    E-Print Network [OSTI]

    Zhang, Jun

    kinetics models or turbulent reacting flows. In this work we are interested in a simple model of laminar structure more accurately, we use the vorticity­velocity formulation of the fluid flow equations [1, 3Preconditioned Multigrid Simulation of an Axisymmetric Laminar Diffusion Flame \\Lambda Samir Karaa

  20. THREE-DIMENSIONAL FLAME PROPAGATION ABOVE LIQUID FUEL POOLS

    E-Print Network [OSTI]

    Liu, Feng

    . One-step chemical kinetics, Fickian diffusion, Fourier heat conduction, and laminar flow with variable are studied. Opposed air flow to the flame spread due to forced and=or natural convection is considered temperature by using a two-dimensional computational fluid dynamics code that solves the coupled equations

  1. On flame kernel formation and propagation in premixed gases

    SciTech Connect (OSTI)

    Eisazadeh-Far, Kian; Metghalchi, Hameed [Northeastern University, Mechanical and Industrial Engineering Department, Boston, MA 02115 (United States); Parsinejad, Farzan [Chevron Oronite Company LLC, Richmond, CA 94801 (United States); Keck, James C. [Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2010-12-15

    Flame kernel formation and propagation in premixed gases have been studied experimentally and theoretically. The experiments have been carried out at constant pressure and temperature in a constant volume vessel located in a high speed shadowgraph system. The formation and propagation of the hot plasma kernel has been simulated for inert gas mixtures using a thermodynamic model. The effects of various parameters including the discharge energy, radiation losses, initial temperature and initial volume of the plasma have been studied in detail. The experiments have been extended to flame kernel formation and propagation of methane/air mixtures. The effect of energy terms including spark energy, chemical energy and energy losses on flame kernel formation and propagation have been investigated. The inputs for this model are the initial conditions of the mixture and experimental data for flame radii. It is concluded that these are the most important parameters effecting plasma kernel growth. The results of laminar burning speeds have been compared with previously published results and are in good agreement. (author)

  2. Paper # B03 Topic: Turbulent Flames US Combustion Meeting

    E-Print Network [OSTI]

    Pitsch, Heinz

    a crucial role in transferring chemical energy stored in fossil fuels into heat. It has been estimatedPaper # B03 Topic: Turbulent Flames 5th US Combustion Meeting Organized by the Western States subfilter model, which is designed for inhomogeneous flow in complex configurations, is employed. Laminar

  3. Simulation of premixed turbulent flames M. Day and J. Bell

    E-Print Network [OSTI]

    Bell, John B.

    -emissions burners for a variety of industrial applications. However, it is difficult to design lean premixed systems domain was 12 cm on a side. The fuel duct in the Bunsen flame is 2.5×5 cm, as are the two pilot burners

  4. LES of a Hydrogen-Enriched Lean Turbulent Premixed Flame

    E-Print Network [OSTI]

    Groth, Clinton P. T.

    - tends the lean stability limit and decreases emissions of carbon monoxide (CO), nitrogen oxides (NOx) to the prediction of H2-enriched lean methane-air turbulent premixed combustion is considered. A presumed conditional mo- ment (PCM) subfilter-scale combustion model is coupled with the flame prolongation

  5. Scalar dissipation rate based flamelet modelling of turbulent premixed flames

    E-Print Network [OSTI]

    Kolla, Hemanth

    2010-03-16

    of species formation rates in the flame zone are required while from the point of view of thermo--acoustics the prediction of spatial variation of heat release rate is crucial; both tasks are challenging but imperative in CFD based design of combustion...

  6. Investigation of polarization spectroscopy for detecting atomic hydrogen in flames 

    E-Print Network [OSTI]

    Kulatilaka, Waruna Dasal

    2002-01-01

    stabilized on near-adiabatic calibration burner (the Hencken burner). The LIPS signal was found to be nearly proportional to the square of the pump beam intensity over a wide range of flame equivalence ratios. Spectral line shapes of hydrogen 1S-4P...

  7. RICH METHANE PREMIXED LAMINAR FLAMES DOPED BY LIGHT UNSATURATED HYDROCARBONS

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    RICH METHANE PREMIXED LAMINAR FLAMES DOPED BY LIGHT UNSATURATED HYDROCARBONS PART I: ALLENE developed in our laboratory for the reactions of C3-C4 unsaturated hydrocarbons. The main reaction pathways2007 #12;3 INTRODUCTION Soots and polyaromatic hydrocarbons (PAH), which are present in the exhaust gas

  8. Soot superaggregates from flaming wildfires and their direct radiative forcing

    E-Print Network [OSTI]

    the ubiquitous presence of soot superaggregates (SAs) in the outflow from a major wildfire in India. SAs, and Da # 300 nm that form via the cluster-dense aggregation mechanism. We present additional observations--such as prescribed and slash burns--as a function of various process parameters such as fuel type, flame temperature

  9. Small-scale Interaction of Turbulence with Thermonuclear Flames in Type Ia Supernovae

    E-Print Network [OSTI]

    J. C. Niemeyer; W. K. Bushe; G. R. Ruetsch

    1999-05-07

    Microscopic turbulence-flame interactions of thermonuclear fusion flames occuring in Type Ia Supernovae were studied by means of incompressible direct numerical simulations with a highly simplified flame description. The flame is treated as a single diffusive scalar field with a nonlinear source term. It is characterized by its Prandtl number, Pr << 1, and laminar flame speed, S_L. We find that if S_L ~ u', where u' is the rms amplitude of turbulent velocity fluctuations, the local flame propagation speed does not significantly deviate from S_L even in the presence of velocity fluctuations on scales below the laminar flame thickness. This result is interpreted in the context of subgrid-scale modeling of supernova explosions and the mechanism for deflagration-detonation-transitions.

  10. Influence of the radiation absorbed by micro particles on the flame propagation and combustion regimes

    E-Print Network [OSTI]

    Ivanov, M F; Liberman, M A

    2015-01-01

    Thermal radiation of the hot combustion products usually does not influence noticeably the flame propagating through gaseous mixture. the situation is changed drastically in the presence even small concentration of particles, which absorb radiation, transfer the heat to the surrounding unburned gaseous mixture by means of heat conduction, so that the gas phase temperature in front of the advancing flame lags that of the particles. It is shown that radiative preheating of unreacted mixture ahead of the flame results in a modest increase of the advancing flame velocity for a highly reactive gaseous fuel, or to considerable increase of the flame velocity in the case of a slow reactive mixture. The effects of radiation preheating as stronger as smaller the normal flame velocity. The radiation heat transfer can become a dominant mechanism compared with molecular heat conduction, determining the structure and the speed of combustion wave in the case of a small enough velocity of the advancing flame. It is shown tha...

  11. Shuttle-mediated proton pumping across the inner mitochondrial membrane

    E-Print Network [OSTI]

    Anatoly Yu. Smirnov; Sergey E. Savel'ev; Franco Nori

    2008-06-19

    Shuttle-assisted charge transfer is pivotal for the efficient energy transduction from the food-stuff electrons to protons in the respiratory chain of animal cells and bacteria. The respiratory chain consists of four metalloprotein Complexes (I-IV) embedded in the inner membrane of a mitochondrion. Three of these complexes pump protons across the membrane, fuelled by the energy of food-stuff electrons. Despite extensive biochemical and biophysical studies, the physical mechanism of this proton pumping is still not well understood. Here we present a nanoelectromechanical model of the electron-driven proton pump related to the second loop of the respiratory chain, where a lipid-soluble ubiquinone molecule shuttles between the Complex I and Complex III, carrying two electrons and two protons. We show that the energy of electrons can be converted to the transmembrane proton potential gradient via the electrostatic interaction between electrons and protons on the shuttle. We find that the system can operate either as a proton pump, or, in the reverse regime, as an electron pump. For membranes with various viscosities, we demonstrate that the uphill proton current peaks near the body temperature $T \\approx 37 ^{\\circ}$C.

  12. Real Time Flame Monitoring of Gasifier and Injectors

    SciTech Connect (OSTI)

    Zelepouga, Serguei; Saveliev, Alexei

    2011-12-31

    This project is a multistage effort with the final goal to develop a practical and reliable nonintrusive gasifier injector monitor to assess burner wear and need for replacement. The project team included the National Energy Technology Laboratory (NETL), Gas Technology Institute (GTI), North Carolina State University, and ConocoPhillips. This report presents the results of the sensor development and testing initially at GTI combustion laboratory with natural gas flames, then at the Canada Energy Technology Center (CANMET), Canada in the atmospheric coal combustor as well as in the pilot scale pressurized entrained flow gasifier, and finally the sensor capabilities were demonstrated at the Pratt and Whitney Rocketdyne (PWR) Gasifier and the Wabash River Repowering plant located in West Terre Haute, IN. The initial tests demonstrated that GTI gasifier sensor technology was capable of detecting shape and rich/lean properties of natural gas air/oxygen enriched air flames. The following testing at the Vertical Combustor Research Facility (VCRF) was a logical transition step from the atmospheric natural gas flames to pressurized coal gasification environment. The results of testing with atmospheric coal flames showed that light emitted by excited OH* and CH* radicals in coal/air flames can be detected and quantified. The maximum emission intensities of OH*, CH*, and black body (char combustion) occur at different axial positions along the flame length. Therefore, the excitation rates of CH* and OH* are distinct at different stages of coal combustion and can be utilized to identify and characterize processes which occur during coal combustion such as devolatilization, char heating and burning. To accomplish the goals set for Tasks 4 and 5, GTI utilized the CANMET Pressurized Entrained Flow Gasifier (PEFG). The testing parameters of the PEFG were selected to simulate optimum gasifier operation as well as gasifier conditions normally resulting from improper operation or failed gasifier injectors. The sensor developed under previous tasks was used to assess the spectroscopic characteristics of the gasifier flame. The obtained spectral data were successfully translated into flame temperature measurements. It was also demonstrated that the reduced spectral data could be very well correlated with very important gasification process parameters such as the air/fuel and water/fuel ratio. Any of these parameters (temperature, air/fuel, and water/fuel) is sufficient to assess burner wear; however, the tested sensor was capable of monitoring all three of them plus the flame shape as functions of burner wear. This will likely be a very powerful tool which should enable significant improvements in gasifier efficiency, reliability, and availability. The sensor technology was presented to the projectâ??s industrial partner (ConocoPhillips). The partner expressed its strong interest in continuing to participate in the field validation phase of GTI's Flame Monitor Project. Finally the sensor was tested in the PWR (Pratt & Whitney Rocketdyne) gasification plant located at GTIâ??s research campus and at the ConocoPhillips industrial scale gasifier at Wabash River Indiana. The field trials of the GTI Gasifier sensor modified to withstand high temperature and pressure corrosive atmosphere of the industrial entrain flow gasifier. The project team successfully demonstrated the Gasifier Sensor system ability to monitor gasifier interior temperature maintaining unobstructed optical access for in excess of six week without any maintenance. The sensor examination upon completion of the trial revealed that the system did not sustain any damage and required minor cleanup of the optics.

  13. Combustion instabilities in sudden expansion oxy-fuel flames

    SciTech Connect (OSTI)

    Ditaranto, Mario; Hals, Joergen

    2006-08-15

    An experimental study on combustion instability is presented with focus on oxy-fuel type combustion. Oxidants composed of CO{sub 2}/O{sub 2} and methane are the reactants flowing through a premixer-combustor system. The reaction starts downstream a symmetric sudden expansion and is at the origin of different instability patterns depending on oxygen concentration and Reynolds number. The analysis has been conducted through measurement of pressure, CH* chemiluminescence, and velocity. As far as stability is concerned, oxy-fuel combustion with oxygen concentration similar to that found in air combustion cannot be sustained, but requires at least 30% oxygen to perform in a comparable manner. Under these conditions and for the sudden expansion configuration used in this study, the instability is at low frequency and low amplitude, controlled by the flame length inside the combustion chamber. Above a threshold concentration in oxygen dependent on equivalence ratio, the flame becomes organized and concentrated in the near field. Strong thermoacoustic instability is then triggered at characteristic acoustic modes of the system. Different modes can be triggered depending on the ratio of flame speed to inlet velocity, but for all types of instability encountered, the heat release and pressure fluctuations are linked by a variation in mass-flow rate. An acoustic model of the system coupled with a time-lag-based flame model made it possible to elucidate the acoustic mode selection in the system as a function of laminar flame speed and Reynolds number. The overall work brings elements of reflection concerning the potential risk of strong pressure oscillations in future gas turbine combustors for oxy-fuel gas cycles. (author)

  14. The Effects of Non-Unity Lewis Numbers on Turbulent Premixed Flame Interactions in a Twin V-flame Configuration

    E-Print Network [OSTI]

    Dunstan, T. D.; Swaminathan, N.; Bray, K. N. C.; Kingsbury, N. G.

    2013-05-16

    ). The turbulence Reynolds number at the inflow plane is Rel0 = u?inl0in/?in = 82, where ?in is the kinematic viscosity of the inflowing mixture, for all the flames simulated in this study. 3 Data Analysis After initialising the fields, the simulations are allowed...

  15. Spatially distributed flame transfer functions for predicting combustion dynamics in lean premixed gas turbine combustors

    SciTech Connect (OSTI)

    Kim, K.T.; Lee, J.G.; Quay, B.D.; Santavicca, D.A.

    2010-09-15

    The present paper describes a methodology to improve the accuracy of prediction of the eigenfrequencies and growth rates of self-induced instabilities and demonstrates its application to a laboratory-scale, swirl-stabilized, lean-premixed, gas turbine combustor. The influence of the spatial heat release distribution is accounted for using local flame transfer function (FTF) measurements. The two-microphone technique and CH{sup *} chemiluminescence intensity measurements are used to determine the input (inlet velocity perturbation) and the output functions (heat release oscillation), respectively, for the local flame transfer functions. The experimentally determined local flame transfer functions are superposed using the flame transfer function superposition principle, and the result is incorporated into an analytic thermoacoustic model, in order to predict the linear stability characteristics of a given system. Results show that when the flame length is not acoustically compact the model prediction calculated using the local flame transfer functions is better than the prediction made using the global flame transfer function. In the case of a flame in the compact flame regime, accurate predictions of eigenfrequencies and growth rates can be obtained using the global flame transfer function. It was also found that the general response characteristics of the local FTF (gain and phase) are qualitatively the same as those of the global FTF. (author)

  16. The response of buoyant laminar diffusion flames to low-frequency forcing

    SciTech Connect (OSTI)

    Williams, Timothy C.; Shaddix, Christopher R.; Schefer, Robert W. [Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94550 (United States); Desgroux, Pascale [Physicochimie des Processus de Combustion et de l'Atmosphere, Universite des Sciences et Technologies de Lille, Villeneuve d'Ascq Cedex (France)

    2007-12-15

    Buoyant jet diffusion flames are frequently used to investigate phenomena associated with flares or fires, such as the formation and emission of soot, polycyclic aromatic hydrocarbons (PAH), and carbon monoxide (CO). To systematically investigate the influence of transient vortex-flame interactions on these processes, laminar jet flames may be periodically forced. Previous work has demonstrated that forcing the fuel stream at a (low) frequency close to the natural buoyant instability frequency will trigger the production of vortices on the air side of the high-temperature reaction zone, coupling the overall flame response to the forcing frequency. In the work reported here, measurements in methane/air and ethylene/air slot flames show that over a substantial range of forcing frequencies and amplitudes, the dominant, air-side vortex production is locked at precisely one-half the excitation frequency of the fuel stream. This phenomenon is examined in detail through the utilization of several laser diagnostic techniques, yielding measurements of both the frequency response of the flames and phase-locked images of the internal flame structure. Under some conditions the subharmonic response of the flame leads to transient separation of the PAH and soot layers from the surrounding high-temperature flame zone, potentially affecting the soot formation and radiation processes. This data should provide useful information for comparison with detailed modeling aimed to improve the understanding of the complex nature of the buoyant instability in jet flames. (author)

  17. An experimental investigation of thermoacoustic instabilities in a premixed swirl-stabilized flame

    SciTech Connect (OSTI)

    Fritsche, D.; Fueri, M.; Boulouchos, K.

    2007-10-15

    Modern gas turbines use lean premixed combustion to achieve the best compromise between pollutant emissions and efficiency. This type of combustion increases the flame receptivity to external perturbations, thereby promoting the onset of large-amplitude pressure oscillations called thermoacoustic instabilities (often referred to as combustion noise). To improve our understanding of stability properties in such complex systems, encountered in many industrial applications, the flame structure of an atmospheric swirl-stabilized burner of 30 to 75 kW was systematically investigated for various inlet temperatures and air-fuel ratios. This investigation revealed the existence of two stable flame types (one lean and one rich) separated by a region of unstable flames characterized by very distinct flame shapes, flame pressure drops, and dynamic pressure oscillations. The lean transition from stable to unstable flames has been associated with a critical flame temperature at the edge of two different flame-stabilizing mechanisms, while the rich transition from unstable to stable flames has been attributed to a critical ratio of hydrodynamic to combustion times in terms of Damkoehler number. In this noise island, the mechanism for instability is due to the nonmonotonic behavior of flame pressure drop as the air-fuel ratio is changed, the maximum pressure drop across the flame coinciding with the maximum dynamic pressure. Finally, the frequency analysis of the dynamic pressure revealed the coupling with the acoustic eigenmodes of the combustion chamber for the dominant mode and with the plenum for secondary ones the frequency of which did not change with flame temperature. (author)

  18. Partially-Premixed Flames in Internal Combustion Engines

    SciTech Connect (OSTI)

    Robert W. Pitz; Michael C. Drake; Todd D. Fansler; Volker Sick

    2003-11-05

    This was a joint university-industry research program funded by the Partnerships for the Academic-Industrial Research Program (PAIR). The research examined partially premixed flames in laboratory and internal combustion engine environments at Vanderbilt University, University of Michigan, and General Motors Research and Development. At Vanderbilt University, stretched and curved ''tubular'' premixed flames were measured in a unique optically accessible burner with laser-induced spontaneous Raman scattering. Comparisons of optically measured temperature and species concentration profiles to detailed transport, complex chemistry simulations showed good correspondence at low-stretch conditions in the tubular flame. However, there were significant discrepancies at high-stretch conditions near flame extinction. The tubular flame predictions were found to be very sensitive to the specific hydrogen-air chemical kinetic mechanism and four different mechanisms were compared. In addition, the thermo-diffusive properties of the deficient reactant, H2, strongly affected the tubular flame structure. The poor prediction near extinction is most likely due to deficiencies in the chemical kinetic mechanisms near extinction. At the University of Michigan, an optical direct-injected engine was built up for laser-induced fluorescence imaging experiments on mixing and combustion under stratified charge combustion conditions with the assistance of General Motors. Laser attenuation effects were characterized both experimentally and numerically to improve laser imaging during the initial phase of the gasoline-air mixture development. Toluene was added to the isooctane fuel to image the fuel-air equivalence ratio in an optically accessible direct-injected gasoline engine. Temperature effects on the toluene imaging of fuel-air equivalence ratio were characterized. For the first time, oxygen imaging was accomplished in an internal combustion engine by combination of two fluorescence trackers, toluene and 3-pentanone. With this method, oxygen, fuel and equivalence ratio were measured in the cylinder. At General Motors, graduate students from the University of Michigan and Vanderbilt University worked with GM researchers to develop high-speed imaging methods for optically accessible direct-injection engines. Spark-emission spectroscopy was combined with high-speed spectrally-resolved combustion imaging in a direct-injected engine.

  19. DIMETHYL ETHER (DME)-FUELED SHUTTLE BUS DEMONSTRATION PROJECT

    SciTech Connect (OSTI)

    Elana M. Chapman; Shirish Bhide; Jennifer Stefanik; Andre L. Boehman; David Klinikowski

    2003-04-01

    The objectives of this research and demonstration program are to convert a campus shuttle bus to operation on dimethyl ether, a potential ultra-clean alternative diesel fuel. To accomplish this objective, this project includes laboratory evaluation of a fuel conversion strategy, as well as, field demonstration of the DME-fueled shuttle bus. Since DME is a fuel with no lubricity (i.e., it does not possess the lubricating quality of diesel fuel), conventional fuel delivery and fuel injection systems are not compatible with dimethyl ether. Therefore, to operate a diesel engine on DME one must develop a fuel-tolerant injection system, or find a way to provide the necessary lubricity to the DME. In this project, they have chosen the latter strategy in order to achieve the objective with minimal need to modify the engine. The strategy is to blend DME with diesel fuel, to obtain the necessary lubricity to protect the fuel injection system and to achieve low emissions. The laboratory studies have included work with a Navistar V-8 turbodiesel engine, demonstration of engine operation on DME-diesel blends and instrumentation for evaluating fuel properties. The field studies have involved performance, efficiency and emissions measurements with the Champion Motorcoach ''Defender'' shuttle bus which will be converted to DME-fueling. The results include baseline emissions, performance and combustion measurements on the Navistar engine for operation on a federal low sulfur diesel fuel (300 ppm S). Most recently, they have completed engine combustion studies on DME-diesel blends up to 30 wt% DME addition.

  20. Alternative Fuels Data Center: Propane Powers Airport Shuttles in New

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 OutreachProductswsicloudwsiclouddenDVA N C E D B L O O D S TA IMarylandOrleans Propane Powers Airport Shuttles

  1. DOE HQ Shuttle Bus Schedule and Route | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE: Alternative Fuels DataEnergy Webinar:IAbout Us »Buildings DOEDOE F 1340.3 DOEGuidanceShuttle

  2. Analysis of the laminar flamelet concept for nonpremixed laminar flames

    SciTech Connect (OSTI)

    Claramunt, K.; Consul, R.; Carbonell, D.; Perez-Segarra, C.D.

    2006-06-15

    The goal of this paper is to investigate the application of the laminar flamelet concept to the multidimensional numerical simulation of nonpremixed laminar flames. The performance of steady and unsteady flamelets is analyzed. The deduction of the mathematical formulation of flamelet modeling is exposed and some commonly used simplifications are examined. Different models for the scalar dissipation rate dependence on the mixture fraction variable are analyzed. Moreover, different criteria to evaluate the Lagrangian-type flamelet lifetime for unsteady flamelets are investigated. Inclusion of phenomena such as differential diffusion with constant Lewis number for each species and radiation heat transfer are also studied. A confined co-flow axisymmetric nonpremixed methane/air laminar flame experimentally investigated by McEnally and Pfefferle (Combust. Sci. Technol. 116-117 (1996) 183-209) and numerically investigated by Bennett, McEnally, Pfefferle, and Smooke (Combust. Flame 123 (2000) 522-546), Consul, Perez-Segarra, Claramunt, Cadafalch, and Oliva (Combust. Theory Modelling 7 (3) (2003) 525-544), and Claramunt, Consul, Perez-Segarra, and Oliva (Combust. Flame 137 (2004) 444-457) has been used as a test case. Results obtained using the flamelet concept have been compared to data obtained from the full resolution of the complete transport equations using primitive variables. Finite-volume techniques over staggered grids are used to discretize the governing equations. A parallel multiblock algorithm based on domain decomposition techniques running with loosely coupled computers has been used. To assess the quality of the numerical solutions presented in this paper, a verification process based on the generalized Richardson extrapolation technique and on the grid convergence index (GCI) has been applied. (author)

  3. Numerical investigation of spontaneous flame propagation under RCCI conditions

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bhagatwala, Ankit V; Sankaran, Ramanan; Kokjohn, Sage; Chen, Jacqueline H

    2015-06-30

    This paper presents results from one and two-dimensional direct numerical simulations under Reactivity Controlled Compression Ignition (RCCI) conditions of a primary reference fuel (PRF) mixture consisting of n-heptane and iso-octane. RCCI uses in-cylinder blending of two fuels with different autoignition characteristics to control combustion phasing and the rate of heat release. These simulations employ an improved model of compression heating through mass source/sink terms developed in a previous work by Bhagatwala et al. (2014), which incorporates feedback from the flow to follow a predetermined experimental pressure trace. Two-dimensional simulations explored parametric variations with respect to temperature stratification, pressure profiles andmore »n-heptane concentration. Furthermore, statistics derived from analysis of diffusion/reaction balances locally normal to the flame surface were used to elucidate combustion characteristics for the different cases. Both deflagration and spontaneous ignition fronts were observed to co-exist, however it was found that higher n-heptane concentration provided a greater degree of flame propagation, whereas lower n-heptane concentration (higher fraction of iso-octane) resulted in more spontaneous ignition fronts. A significant finding was that simulations initialized with a uniform initial temperature and a stratified n-heptane concentration field, resulted in a large fraction of combustion occurring through flame propagation. The proportion of spontaneous ignition fronts increased at higher pressures due to shorter ignition delay when other factors were held constant. For the same pressure and fuel concentration, the contribution of flame propagation to the overall combustion was found to depend on the level of thermal stratification, with higher initial temperature gradients resulting in more deflagration and lower gradients generating more ignition fronts. Statistics of ignition delay are computed to assess the Zel’dovich (1980) theory for the mode of combustion propagation based on ignition delay gradients.« less

  4. On the small-scale stability of thermonuclear flames in Type Ia supernovae

    E-Print Network [OSTI]

    F. K. Roepke; J. C. Niemeyer; W. Hillebrandt

    2003-05-02

    We present a numerical model which allows us to investigate thermonuclear flames in Type Ia supernova explosions. The model is based on a finite-volume explicit hydrodynamics solver employing PPM. Using the level-set technique combined with in-cell reconstruction and flux-splitting schemes we are able to describe the flame in the discontinuity approximation. We apply our implementation to flame propagation in Chandrasekhar-mass Type Ia supernova models. In particular we concentrate on intermediate scales between the flame width and the Gibson-scale, where the burning front is subject to the Landau-Darrieus instability. We are able to reproduce the theoretical prediction on the growth rates of perturbations in the linear regime and observe the stabilization of the flame in a cellular shape. The increase of the mean burning velocity due to the enlarged flame surface is measured. Results of our simulation are in agreement with semianalytical studies.

  5. Fuel effects on flame lift-off under diesel conditions

    SciTech Connect (OSTI)

    Persson, Helena; Andersson, Oeivind; Egnell, Rolf

    2011-01-15

    An apparent relation between the lift-off length under diesel conditions and the ignition quality of a fuel has previously been reported. To cast light on the underlying mechanism, the current study aims to separate flame lift-off effects of the chemical ignition delay from those of other fuel properties under diesel conditions. Flame lift-off was measured in an optical diesel engine by high-speed video imaging of OH-chemiluminescence. Fuel and ambient-gas properties were varied during the experiment. Only a weak correlation was found between ignition delay and lift-off length. The data indicate that this correlation is due to a common, stronger correlation with the ambient oxygen concentration. The chemical ignition delay and the fuel type had similar, weak effects on the lift-off length. A recently proposed mechanism for lift-off stabilization was used to interpret the results. It assumes that reactants approaching the lift-off position of the jet are mixed with high-temperature products found along the edges of the flame, which trigger autoignition. In this picture, the fuel effect is most likely due to differences in the amount of mixing with high-temperature products that is required for autoignition. In the current experiment, all lift-off effects seem to arise from variations in the reactant and product temperatures, induced by fuel and ambient properties. (author)

  6. At What Distance Can the Human Eye Detect a Candle Flame?

    E-Print Network [OSTI]

    Krisciunas, Kevin

    2015-01-01

    Using CCD observations of a candle flame situated at a distance of 338 m and calibrated with observations of Vega, we show that a candle flame situated at ~2.6 km (1.6 miles) is comparable in brightness to a 6th magnitude star with the spectral energy distribution of Vega. The human eye cannot detect a candle flame at 10 miles or further, as some statements on the web suggest.

  7. Turbulent Flame Speeds and NOx Kinetics of HHC Fuels with Contaminants and High Dilution Levels

    SciTech Connect (OSTI)

    Peterson, Eric; Krejci, Michael; Mathieu, Olivier; Vissotski, Andrew; Ravi, Sankat; Plichta, Drew; Sikes, Travis; Levacque, Anthony; Camou, Alejandro; Aul, Christopher

    2013-09-30

    This final report documents the technical results of the 3-year project entitled, “Turbulent Flame Speeds and NOx Kinetics of HHC Fuels with Contaminants and High Dilution Levels,” funded under the NETL of DOE. The research was conducted under six main tasks: 1) program management and planning; 2) turbulent flame speed measurements of syngas mixtures; 3) laminar flame speed measurements with diluents; 4) NOx mechanism validation experiments; 5) fundamental NOx kinetics; and 6) the effect of impurities on NOx kinetics. Experiments were performed using primary constant-volume vessels for laminar and turbulent flame speeds and shock tubes for ignition delay times and species concentrations. In addition to the existing shock- tube and flame speed facilities, a new capability in measuring turbulent flame speeds was developed under this grant. Other highlights include an improved NOx kinetics mechanism; a database on syngas blends for real fuel mixtures with and without impurities; an improved hydrogen sulfide mechanism; an improved ammonia kintics mechanism; laminar flame speed data at high pressures with water addition; and the development of an inexpensive absorption spectroscopy diagnostic for shock-tube measurements of OH time histories. The Project Results for this work can be divided into 13 major sections, which form the basis of this report. These 13 topics are divided into the five areas: 1) laminar flame speeds; 2) Nitrogen Oxide and Ammonia chemical kinetics; 3) syngas impurities chemical kinetics; 4) turbulent flame speeds; and 5) OH absorption measurements for chemical kinetics.

  8. Direct numerical simulations of type Ia supernovae flames II: The rayleigh-taylor instability

    E-Print Network [OSTI]

    Bell, J.B.; Day, M.S.; Rendleman, C.A.; Woosley, S.E.; Zingale, M.

    2004-01-01

    Weaver, T. A. 1994, in Supernovae, Les Houches, Session LIV,Simulations of Type Ia Supernovae Flames II: The Rayleigh-Subject headings: supernovae: general — white dwarfs —

  9. Direct numerical simulations of type Ia supernovae flames I: The landau-darrieus instability

    E-Print Network [OSTI]

    Bell, J.B.; Day, M.S.; Rendleman, C.A.; Woosley, S.E.; Zingale, M.

    2003-01-01

    Simulations of Type Ia Supernovae Flames I: The Landau-Subject headings: supernovae: general — white dwarfs —could occur in Type Ia supernovae (Niemeyer & Woosley 1997),

  10. Unsteady behavior of locally strained diffusion flames affected by curvature and preferential diffusion

    SciTech Connect (OSTI)

    Yoshida, Kenji; Takagi, Toshimi

    1999-07-01

    Experimental and numerical studies are made of transient H{sub 2}/N{sub 2}--air counterflow diffusion flames unsteadily strained by an impinging micro jet. Two-dimensional temperature measurements by laser Rayleigh scattering method and numerical computations taking into account detailed chemical kinetics are conducted paying attention to transient local extinction and reignition in relation to the unsteadiness, flame curvature and preferential diffusion effects. The results are as follows. (1) Transient local flame extinction is observed where the micro jet impinges. But, the transient flame can survive instantaneously in spite of quite high stretch rate where the steady flame cannot exist. (2) Reignition is observed after the local extinction due to the micro air jet impingement. The temperature after reignition becomes significantly higher than that of the original flame. This high temperature is induced by the concentration of H{sub 2} species due to the preferential diffusion in relation to the concave curvature. The predicted behaviors of the local transient extinction and reignition are well confirmed by the experiments. (3) The reignition is induced after the formation of combustible premixed gas mixture and the consequent flame propagation. (4) The reignition is hardly observed after the extinction by micro fuel jet impingement. This is due to the dilution of H{sub 2} species induced by the preferential diffusion in relation to the convex curvature. (5) The maximum flame temperature cannot be rationalized by the stretch rate but changes widely depending on the unsteadiness and the flame curvature in relation with preferential diffusion.

  11. SuperShuttle CNG Fleet Study Summary; Resumen de Estuidio de la Flotilla de GNC de la Empresa SuperShuttle

    SciTech Connect (OSTI)

    Eudy, L.

    2001-10-01

    An account of the successful use of alternative fuels in a fleet of SuperShuttle passenger vans, which offer shared-rides between Boulder and Denver International Airport.

  12. Denver SuperShuttle CNG Fleet Evaluation; Evaluacion de la flotilla de GNC de la empresa SuperShuttle de Denver

    SciTech Connect (OSTI)

    LaRocque, T.

    2001-10-01

    A description of a joint effort between Denver SuperShuttle, the Gas Research Institute (GRI) and DOE that evaluated two types of bi-fuel and compressed natural gas.

  13. Autoignited laminar lifted flames of methane, ethylene, ethane, and n-butane jets in coflow air with elevated temperature

    SciTech Connect (OSTI)

    Choi, B.C.; Chung, S.H.

    2010-12-15

    The autoignition characteristics of laminar lifted flames of methane, ethylene, ethane, and n-butane fuels have been investigated experimentally in coflow air with elevated temperature over 800 K. The lifted flames were categorized into three regimes depending on the initial temperature and fuel mole fraction: (1) non-autoignited lifted flame, (2) autoignited lifted flame with tribrachial (or triple) edge, and (3) autoignited lifted flame with mild combustion. For the non-autoignited lifted flames at relatively low temperature, the existence of lifted flame depended on the Schmidt number of fuel, such that only the fuels with Sc > 1 exhibited stationary lifted flames. The balance mechanism between the propagation speed of tribrachial flame and local flow velocity stabilized the lifted flames. At relatively high initial temperatures, either autoignited lifted flames having tribrachial edge or autoignited lifted flames with mild combustion existed regardless of the Schmidt number of fuel. The adiabatic ignition delay time played a crucial role for the stabilization of autoignited flames. Especially, heat loss during the ignition process should be accounted for, such that the characteristic convection time, defined by the autoignition height divided by jet velocity was correlated well with the square of the adiabatic ignition delay time for the critical autoignition conditions. The liftoff height was also correlated well with the square of the adiabatic ignition delay time. (author)

  14. Combustion-derived flame generated ultrafine soot generates reactive oxygen species and activates Nrf2 antioxidants differently in neonatal and adult rat lungs

    E-Print Network [OSTI]

    2013-01-01

    article as: Chan et al. : Combustion-derived flame generatedRESEARCH Open Access Combustion-derived flame generated6]. Vehicle exhaust from combustion of gasoline, diesel and

  15. Detailed characterization of the dynamics of thermoacoustic pulsations in a lean premixed swirl flame

    SciTech Connect (OSTI)

    Meier, W.; Weigand, P.; Duan, X.R.; Giezendanner-Thoben, R.

    2007-07-15

    A nozzle configuration for technically premixed gas turbine flames was operated with CH{sub 4} and air at atmospheric pressure. The flames were confined by a combustion chamber with large quartz windows, allowing the application of optical and laser diagnostics. In a distinct range of operating conditions the flames exhibited strong self-excited thermoacoustic pulsations at a frequency around 290 Hz. A flame with P=25kW thermal power and an equivalence ratio of {phi}=0.7 was chosen as a target flame in order to analyze the dynamics and the feedback mechanism of the periodic instability in detail. The velocity field was measured by three-component laser Doppler velocimetry, the flame structures were measured by chemiluminescence imaging and planar laser-induced fluorescence of OH, and the joint probability density functions of major species concentrations, mixture fraction, and temperature were measured by laser Raman scattering. All measuring techniques were applied in a phase-locked mode with respect to the phase angle of the periodic pulsation. In addition to the pulsating flame, a nonpulsating flame with increased fuel flow rate (P=30kW, {phi}=0.83) was studied for comparison. The measurements revealed significant differences between the structures of the pulsating and the nonpulsating (or ''quiet'') flame. Effects of finite-rate chemistry and unmixedness were observed in both flames but were more pronounced in the pulsating flame. The phase-locked measurements revealed large variations of all measured quantities during an oscillation cycle. This yielded a clear picture of the sequence of events and allowed the feedback mechanism of the instability to be identified and described quantitatively. The data set presents a very good basis for the verification of numerical combustion simulations because the boundary conditions of the experiment were well-defined and the most important quantities were measured with a high accuracy. (author)

  16. Effects of fuel type and equivalence ratios on the flickering of triple flames

    SciTech Connect (OSTI)

    Sahu, K.B.; Kundu, A.; Ganguly, R.; Datta, A.

    2009-02-15

    An experimental study has been conducted in axisymmetric, co-flowing triple flames with different equivalence ratios of the inner and outer reactant streams (2<{phi}{sub in}<3 and 0{<=}{phi}{sub out}<0.7). Different fuel combinations, like propane/propane, propane/methane or methane/methane in the inner and outer streams respectively, have been used in the experiments. The structures of the triple flames have been compared for the different fuel combinations and equivalence ratios. The conditions under which triple flames exhibit oscillation have been identified. During the oscillation, the non-premixed flame and the outer lean premixed flame flicker strongly, while the inner rich premixed flame remains more or less stable. The flickering frequency has been evaluated through image processing and fast Fourier transform (FFT) of the average pixel intensity of the image frames. It is observed that, for all the fuel combinations, the frequency decreases with the increase in the outer equivalence ratio, while it is relatively invariant with the change in the inner equivalence ratio. However, an increase in the inner equivalence ratio affects the structure of the flame by increasing the heights of the inner premixed flame and non-premixed flame and also enlarges the yellow soot-laden zone at the tip of the inner flame. A scaling analysis of the oscillating flames has been performed based on the measured parameters, which show a variation of Strouhal number (St) with Richardson number (Ri) as St {proportional_to} Ri{sup 0.5}. The fuel type is found to have no influence on this correlation. (author)

  17. IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, VOL. 43, NO. 8, AUGUST 2005 1707 Validation of the Shuttle Radar Topography

    E-Print Network [OSTI]

    Sarabandi, Kamal

    of the Shuttle Radar Topography Mission Height Data Charles G. Brown, Jr., Member, IEEE, Kamal Sarabandi, Fellow, IEEE, and Leland E. Pierce, Senior Member, IEEE Abstract--The Shuttle Radar Topography Mission (SRTM Radar Topography Mission, validation. I. INTRODUCTION THE Shuttle Radar Topography Mission (SRTM

  18. Direct measurement of polysulfide shuttle current: A window into understanding the performance of lithium-sulfur cells

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Moy, Derek; Manivannan, A.; Narayanan, S. R.

    2014-11-04

    The shuttling of polysulfide ions between the electrodes in a lithium-sulfur battery is a major technical issue limiting the self-discharge and cycle life of this high-energy rechargeable battery. Although there have been attempts to suppress the shuttling process, there has not been a direct measurement of the rate of shuttling. We report here a simple and direct measurement of the rate of the shuttling (that we term “shuttle current”), applicable to the study of any type of lithium-sulfur cell. We demonstrate the effectiveness of this measurement technique using cells with and without lithium nitrate (a widely-used shuttle suppressor additive). Wemore »present a phenomenological analysis of the shuttling process and simulate the shuttle currents as a function of the state-of-charge of a cell. We also demonstrate how the rate of decay of the shuttle current can be used to predict the capacity fade in a lithium-sulfur cell due to the shuttle process. As a result, we expect that this new ability to directly measure shuttle currents will provide greater insight into the performance differences observed with various additives and electrode modifications that are aimed at suppressing the rate of shuttling of polysulfide ions and increasing the cycle life of lithium-sulfur cells.« less

  19. Direct measurement of polysulfide shuttle current: A window into understanding the performance of lithium-sulfur cells

    SciTech Connect (OSTI)

    Moy, Derek; Manivannan, A.; Narayanan, S. R.

    2014-11-04

    The shuttling of polysulfide ions between the electrodes in a lithium-sulfur battery is a major technical issue limiting the self-discharge and cycle life of this high-energy rechargeable battery. Although there have been attempts to suppress the shuttling process, there has not been a direct measurement of the rate of shuttling. We report here a simple and direct measurement of the rate of the shuttling (that we term “shuttle current”), applicable to the study of any type of lithium-sulfur cell. We demonstrate the effectiveness of this measurement technique using cells with and without lithium nitrate (a widely-used shuttle suppressor additive). We present a phenomenological analysis of the shuttling process and simulate the shuttle currents as a function of the state-of-charge of a cell. We also demonstrate how the rate of decay of the shuttle current can be used to predict the capacity fade in a lithium-sulfur cell due to the shuttle process. As a result, we expect that this new ability to directly measure shuttle currents will provide greater insight into the performance differences observed with various additives and electrode modifications that are aimed at suppressing the rate of shuttling of polysulfide ions and increasing the cycle life of lithium-sulfur cells.

  20. Direct measurement of polysulfide shuttle current: A window into understanding the performance of lithium-sulfur cells

    SciTech Connect (OSTI)

    Moy, Derek [Univ. of Southern California, Los Angeles, CA (United States). Loker Hydrocarbon Research Institute.; Manivannan, A. [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Narayanan, S. R. [Univ. of Southern California, Los Angeles, CA (United States). Loker Hydrocarbon Research Institute.

    2014-11-01

    The shuttling of polysulfide ions between the electrodes in a lithium-sulfur battery is a major technical issue limiting the self-discharge and cycle life of this high-energy rechargeable battery. Although there have been attempts to suppress the shuttling process, there has not been a direct measurement of the rate of shuttling. We report here a simple and direct measurement of the rate of the shuttling (that we term “shuttle current”), applicable to the study of any type of lithium-sulfur cell. We demonstrate the effectiveness of this measurement technique using cells with and without lithium nitrate (a widely-used shuttle suppressor additive). We present a phenomenological analysis of the shuttling process and simulate the shuttle currents as a function of the state-of-charge of a cell. We also demonstrate how the rate of decay of the shuttle current can be used to predict the capacity fade in a lithium-sulfur cell due to the shuttle process. We expect that this new ability to directly measure shuttle currents will provide greater insight into the performance differences observed with various additives and electrode modifications that are aimed at suppressing the rate of shuttling of polysulfide ions and increasing the cycle life of lithium-sulfur cells.

  1. The Structure of Triple Flames Stabilized on a Slot Burner RICCARDO AZZONI, STEFANO RATTI, SURESH K. AGGARWAL, and

    E-Print Network [OSTI]

    Aggarwal, Suresh K.

    The Structure of Triple Flames Stabilized on a Slot Burner RICCARDO AZZONI, STEFANO RATTI, SURESH K, not clearly understood. Herein, laminar triple flames stabilized on a Wolfhard-Parker slot burner

  2. Phase control in the synthesis of yttrium oxide nano and micro-particles by flame spray pyrolysis 

    E-Print Network [OSTI]

    Mukundan, Mallika

    2009-05-15

    The project synthesizes phase pure Yttria particles using flame spray pyrolysis, and to experimentally determines the effect of various process parameters like residence time, adiabatic flame temperature and precursor droplet size on the phase...

  3. Soot particle size measurements in laminar premixed ethylene flames with laser-induced incandescence and scanning mobility particle sizer

    E-Print Network [OSTI]

    Yin, Chung-Yuan

    2009-01-01

    Methane, Propane, and Ethylene Diffusion Flames,” CombustionPropane Diffusion Flames,” Applied Optics 40 (15): 2443-2452 (2001) Haynes BS, Wagner HG, “Soot Formation,” Progress in Energy and Combustion

  4. Implementation of two-equation soot flamelet models for laminar diffusion flames

    SciTech Connect (OSTI)

    Carbonell, D.; Oliva, A.; Perez-Segarra, C.D.

    2009-03-15

    The two-equation soot model proposed by Leung et al. [K.M. Leung, R.P. Lindstedt, W.P. Jones, Combust. Flame 87 (1991) 289-305] has been derived in the mixture fraction space. The model has been implemented using both Interactive and Non-Interactive flamelet strategies. An Extended Enthalpy Defect Flamelet Model (E-EDFM) which uses a flamelet library obtained neglecting the soot formation is proposed as a Non-Interactive method. The Lagrangian Flamelet Model (LFM) is used to represent the Interactive models. This model uses direct values of soot mass fraction from flamelet calculations. An Extended version (E-LFM) of this model is also suggested in which soot mass fraction reaction rates are used from flamelet calculations. Results presented in this work show that the E-EDFM predict acceptable results. However, it overpredicts the soot volume fraction due to the inability of this model to couple the soot and gas-phase mechanisms. It has been demonstrated that the LFM is not able to predict accurately the soot volume fraction. On the other hand, the extended version proposed here has been shown to be very accurate. The different flamelet mathematical formulations have been tested and compared using well verified reference calculations obtained solving the set of the Full Transport Equations (FTE) in the physical space. (author)

  5. Freight Shuttle System: Cross-Border Movement of Goods

    SciTech Connect (OSTI)

    None

    2011-05-31

    The Freight Shuttle System (FSS) is designed to provide freight transportation services between those short and intermediate distance locations (within 600 miles) that are currently handling large volumes of freight traffic. Much like trucks, the FSS's transporters are autonomous: each transporter has its own propulsion and travels independently of other transporters. Inspired by railroads, each FSS transporter has steel wheels operating on a steel running surface and can carry either a standardsize freight container or an over-the-road truck trailer. However, unlike either rail or trucks, the FSS runs on an elevated, dedicated guideway to avoid the interference of other transportation systems. The objective of this report is to examine the potential viability for an alternative transportation system for trailers and containers in a multi-national, cross-border setting. The El Paso-Ciudad Juarez region serves as the environment of this analysis.

  6. Near-limit laminar burning velocities of microgravity premixed hydrogen flames

    E-Print Network [OSTI]

    Qiao, Li

    Near-limit laminar burning velocities of microgravity premixed hydrogen flames with chemically of chemically-passive fire suppressants on laminar premixed hydrogen flames were investigated by combined use that provides at least 450 ms of 10À2 g. Near-limit laminar burning velocities were measured for outwardly

  7. Soot formation in high pressure laminar diffusion flames Ahmet E. Karatas *, mer L. Glder

    E-Print Network [OSTI]

    Gülder, Ömer L.

    Review Soot formation in high pressure laminar diffusion flames Ahmet E. Karatas¸ *, Ömer L. Gülder online 30 June 2012 Keywords: High pressure soot formation High pressure combustion Laminar diffusion laminar co-flow diffusion flames burning at elevated pressures. First, a brief review of soot formation

  8. Simulation of Nitrogen Emissions in a Premixed Hydrogen Flame Stabilized on a Low Swirl Burner

    E-Print Network [OSTI]

    Bell, John B.

    Abstract There is considerable interest in developing fuel-flexible, low emissions turbines for power generation. One ap- proach is based on burning a variety of lean premixed fuels with relatively low flame concentration and a corresponding in- crease in local flame temperature just downstream. In turn, these regions

  9. A combined computational and experimental characterization of lean premixed turbulent low swirl laboratory flames.

    E-Print Network [OSTI]

    Bell, John B.

    such as, nitrogen, and carbon dioxide. New fuels with significant hydrogen composition are particularly in fuels proposed for the integrated gasification combined cycle coal power plants with carbon capture-PLIF imaging, and are used to quantify the flow field, mean flame location, and local flame wrinkling

  10. On the Similitude Between Lifted and Burner-Stabilized Triple Flames: A Numerical and Experimental Investigation

    E-Print Network [OSTI]

    Aggarwal, Suresh K.

    On the Similitude Between Lifted and Burner-Stabilized Triple Flames: A Numerical and Experimental first validate our simulations with detailed measurements in more tractable methane­air burner used for investigating the burner-stabilized flames. The similarities and differences between

  11. Simulation of Nitrogen Emissions in a Premixed Hydrogen Flame Stabilized on a Low Swirl Burner

    E-Print Network [OSTI]

    Bell, John B.

    Simulation of Nitrogen Emissions in a Premixed Hydrogen Flame Stabilized on a Low Swirl Burner J. B temperatures. Such flames can be stabilized in a low swirl burner configuration, for example, using a variety in the context of a laboratory-scale low swirl burner fueled with a lean hydrogen-air mixture at atmospheric

  12. A LEAN METHANE PREMIXED LAMINAR FLAME DOPED WITH COMPONENTS OF DIESEL FUEL

    E-Print Network [OSTI]

    Boyer, Edmond

    A LEAN METHANE PREMIXED LAMINAR FLAME DOPED WITH COMPONENTS OF DIESEL FUEL PART I: N-BUTYLBENZENE E better understand the chemistry involved during the combustion of components of diesel fuel flow rate analyses. Keywords: Premixed laminar flame, methane, n-butylbenzene, modelling, diesel fuel

  13. Establishing criteria for the design of a combination parallel and cross-flaming covered burner 

    E-Print Network [OSTI]

    Stark, Christopher Charles

    2003-01-01

    A burner was designed and constructed to combine weed control practices of parallel and cross-flaming with the technology of covers and insulation. It involved two covers designed to be placed on the sides of a crop row. The flame under the covers...

  14. Effects of Coaxial Air on Nitrogen-Diluted Hydrogen Jet Diffusion Flame Length and NOx Emission

    SciTech Connect (OSTI)

    Weiland, N.T.; Chen, R.-H.; Strakey, P.A.

    2007-10-01

    Turbulent nitrogen-diluted hydrogen jet diffusion flames with high velocity coaxial air flows are investigated for their NOx emission levels. This study is motivated by the DOE turbine program’s goal of achieving 2 ppm dry low NOx from turbine combustors running on nitrogen-diluted high-hydrogen fuels. In this study, effects of coaxial air velocity and momentum are varied while maintaining low overall equivalence ratios to eliminate the effects of recirculation of combustion products on flame lengths, flame temperatures, and resulting NOx emission levels. The nature of flame length and NOx emission scaling relationships are found to vary, depending on whether the combined fuel and coaxial air jet is fuel-rich or fuel-lean. In the absence of differential diffusion effects, flame lengths agree well with predicted trends, and NOx emissions levels are shown to decrease with increasing coaxial air velocity, as expected. Normalizing the NOx emission index with a flame residence time reveals some interesting trends, and indicates that a global flame strain based on the difference between the fuel and coaxial air velocities, as is traditionally used, is not a viable parameter for scaling the normalized NOx emissions of coaxial air jet diffusion flames.

  15. Global NOx Measurements in Turbulent Nitrogen-Diluted Hydrogen Jet Flames

    SciTech Connect (OSTI)

    Weiland, N.T.; Strakey, P.A.

    2007-03-01

    Turbulent hydrogen diffusion flames diluted with nitrogen are currently being studied to assess their ability to achieve the DOE Turbine Program’s aggressive emissions goal of 2 ppm NOx in a hydrogen-fueled IGCC gas turbine combustor. Since the unstrained adiabatic flame temperatures of these diluted flames are not low enough to eliminate thermal NOx formation the focus of the current work is to study how the effects of flame residence time and global flame strain can be used to help achieve the stated NOx emissions goal. Dry NOx measurements are presented as a function of jet diameter nitrogen dilution and jet velocity for a turbulent hydrogen/nitrogen jet issuing from a thin-lipped tube in an atmospheric pressure combustor. The NOx emission indices from these experiments are normalized by the flame residence time to ascertain the effects of global flame strain and fuel Lewis Number on the NOx emissions. In addition dilute hydrogen diffusion flame experiments were performed in a high-pressure combustor at 2 4 and 8 atm. The NOx emission data from these experiments are discussed as well as the results from a Computational Fluid Dynamics modeling effort currently underway to help explain the experimental data.

  16. Combustion and Flame 145 (2006) 765778 www.elsevier.com/locate/combustflame

    E-Print Network [OSTI]

    Gülder, Ömer L.

    2006-01-01

    Combustion and Flame 145 (2006) 765­778 www.elsevier.com/locate/combustflame Soot formation and temperature field structure in laminar propane­air diffusion flames at elevated pressures Décio S. Bento Dufferin Street, Toronto, ON M3H 5T6, Canada b National Research Council, ICPET Combustion Technology, 1200

  17. Turbulent premixed flame front dynamics and implications for limits of flamelet hypothesis

    E-Print Network [OSTI]

    Gülder, Ömer L.

    of methane­air and propane­air stabilized on a Bunsen-type burner were studied to investigate the dynamics. The equivalence ratio was varied from 0.6 (0.7 for propane) to stoichiometric. The flame front data were obtained The Combustion Institute. Published by Elsevier Inc. All rights reserved. Keywords: Turbulent premixed flames

  18. Combustion and Flame 150 (2007) 400403 www.elsevier.com/locate/combustflame

    E-Print Network [OSTI]

    Gülder, Ömer L.

    2007-01-01

    - sion, as well as power production, operate at pressures approaching (and sometimes exceeding) 10 MPa- evated pressures, has the potential to shed some light on soot formation in turbulent diffusion flames performed pre- viously with methane [1] and propane [2] diffusion flames at elevated pressures. A constant

  19. Timewise morphology of turbulent diffusion flame by means of image processing

    SciTech Connect (OSTI)

    Torii, Shuichi; Yano, Toshiaki; Tsuchino, Fumihiro

    1999-07-01

    An experimental study is performed to investigate the dynamic behavior of jet diffusion flames from a vertical circular nozzle. A real-time image processing on slow-motion video recording using the high-speed video camera is employed to clarify the flame morphology. Emphasis is placed on the timewise variation of the flame length, H, the peripheral distance of the flame, L, and the projected area of the flame contour, S, based on the RGB values of the flame. Here, RGB implies the three primary colors, i.e., red, green and blue, respectively. Propane is used as fuel and a burner tube of 2.40 mm inside diameter is employed here. It is found from the study that (1) a real-time color image processing with the aid of a slow-motion video recording discriminates the flame shape and discloses the flame behavior with time, (2) H, L and S vary periodically with time, and (3) the time-averaged value of L{sup 2}/S and its turbulence intensity, which is defined here, are intensified with an increase in the Reynolds number.

  20. Studies on non-premixed flame streets in a mesoscale channel

    E-Print Network [OSTI]

    Ju, Yiguang

    Studies on non-premixed flame streets in a mesoscale channel Bo Xu *, Yiguang Ju Department of channel width, wall temperature, and flow rate on the dynamics of non-premix flames in a mesoscale The Combustion Institute. Published by Elsevier Inc. All rights reserved. Keywords: Mesoscale combustion; Non

  1. Structure of Partially Premixed Flames Using Detailed Chemistry Simulations 

    E-Print Network [OSTI]

    Kluzek, Celine D.

    2010-10-12

    in the carburetor engines. The partially premixed ame set up, case b, is achieved by premixing fuel and oxidizer before ignition and adding oxidizer/air by entrainment or with a co- ow. It combines some of the advantages of non-premixed and premixed ames... 2009 Major Subject: Aerospace Engineering STRUCTURE OF PARTIALLY PREMIXED FLAMES USING DETAILED CHEMISTRY SIMULATIONS A Dissertation by CELINE DELPHINE KLUZEK Submitted to the O ce of Graduate Studies of Texas A&M University in partial ful llment...

  2. REAL-TIME FIRE AND FLAME DETECTION IN VIDEO Yigithan Dedeoglu, B. Ugur Toreyin, Ugur Gudukbay, A. Enis C etin

    E-Print Network [OSTI]

    Güdükbay, Ugur

    REAL-TIME FIRE AND FLAME DETECTION IN VIDEO Yigithan Dedeoglu, B. Ugur T¨oreyin, Ugur G¨ud¨ukbay, A method to detect fire and/or flame by processing the video data generated by an ordi- nary camera monitoring a scene. In addition to ordinary motion and color clues, flame and fire flicker is detected

  3. CH(A-X) and OH(A-X) Optical Emission in an Axisymmetric Laminar Diffusion Flame

    E-Print Network [OSTI]

    Long, Marshall B.

    CH(A-X) and OH(A-X) Optical Emission in an Axisymmetric Laminar Diffusion Flame J. LUQUE, J. B an axisymmetric laminar diffusion flame [K. T. Walsh, M. B. Long, M. A. Tanoff, and M. D. Smooke, Twenty axisymmetric laminar methane/air diffusion flame studied here has been exten- sively characterized both

  4. Simulations of a turbulent non-premixed flame using combined dimension reduction and tabulation for combustion chemistry

    E-Print Network [OSTI]

    Simulations of a turbulent non-premixed flame using combined dimension reduction and tabulation simulate a bluff-body-stabilized non-premixed turbulent methane/air flame. " NOx and CO emissions have been flames Dimension reduction Tabulation Constrained equilibrium a b s t r a c t The use of large chemical

  5. Modeling of the formation of short-chain acids in propane flames F. Battin-Leclerc , 1

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Modeling of the formation of short-chain acids in propane flames F. Battin-Leclerc , 1 , A. Simulations of lean (equivalence ratios from 0.9 to 0.48) laminar premixed flames of propane stabilized in a combustion apparatus which can easily be modeled, a laminar premixed flame of propane at atmospheric pressure

  6. Spectroscopic analysis of diesel combustion flame by means of streak camera

    SciTech Connect (OSTI)

    Nagase, K.; Funatsu, K.

    1988-01-01

    Band spectra in ultraviolet and visible ranges contain information on the state of combustion flame. Measurement of those spectra in diesel combustion flame, however, has been regarded as impossible because of the obstruction of bright flame and soot. The phenomena of diesel combustion, therefore, have not been analyzed clearly from the viewpoint of chemical reaction. The authors inserted an optical fiber into the diesel combustion chamber to detect the flame. The combustion flame was recorded by a special spectroscopic apparatus, named Streak camera, and the recorded image was subjected to spectroscopic analysis. The result of the experiments confirmed the existence of band spectra emitted from CH and OH radicals in the ultraviolet and visible ranges. The recorded data made clear the progress of chemical reactions and the formation of intermediate products during the diesel combustion process.

  7. Critical radius for sustained propagation of spark-ignited spherical flames

    SciTech Connect (OSTI)

    Kelley, Andrew P.; Jomaas, Grunde; Law, Chung K.

    2009-05-15

    An experimental study was performed to determine the requirements for sustained propagation of spark-ignited hydrogen-air and butane-air flames at atmospheric and elevated pressures. Results show that sustained propagation is always possible for mixtures whose Lewis number is less than unity, as long as a flame can be initially established. However, for mixtures whose Lewis number is greater than unity, sustained propagation depends on whether the initially ignited flame can attain a minimum radius. This minimum radius was determined for mixtures of different equivalence ratios and pressures, and was found to agree moderately well with the theoretically predicted critical radius beyond which there is no solution for the adiabatic, quasi-steady propagation of the spherical flame. The essential roles of pressure, detailed chemistry, and the need to use local values in the quantitative evaluation of the flame response parameters are emphasized. (author)

  8. Sudden acceleration of flames in open channels driven by hydraulic resistance

    E-Print Network [OSTI]

    Yanez, J; Bykov, V

    2012-01-01

    Hydrogen-air deflagrations with venting at the end of obstructed tubes are studied experimentally and numerically. A shockless transition to the so-called chocked regime of the flame propagation is reported. Mixtures with 13% vol. of hydrogen were ignited from the open end of the tube at the interface between fuel and the ambient air. Three venting ratios were selected, closed, 40% and 100%. In all cases the flame initially propagates without acceleration at a velocity close to the laminar flame speed. The flame configuration excludes most of conventionally acknowledged phenomena of the DDT, namely, volumetric explosions, igniting shock and shock waves interactions. However, after an induction period, of the order of 1 sec, the flame accelerates more than 100 times, within a period of 3-30 ms, until the steady-state choked regime is established. The mechanism of such rapid acceleration is investigated both numerically and analytically. A one dimensional reduced description was suggested and analyzed to model ...

  9. Analysis of the flamelet concept in the numerical simulation of laminar partially premixed flames

    SciTech Connect (OSTI)

    Consul, R.; Oliva, A.; Perez-Segarra, C.D.; Carbonell, D.; de Goey, L.P.H.

    2008-04-15

    The aim of this work is to analyze the application of flamelet models based on the mixture fraction variable and its dissipation rate to the numerical simulation of partially premixed flames. Although the main application of these models is the computation of turbulent flames, this work focuses on the performance of flamelet concept in laminar flame simulations removing, in this way, turbulence closure interactions. A well-known coflow methane/air laminar flame is selected. Five levels of premixing are taken into account from an equivalence ratio {phi}={infinity} (nonpremixed) to {phi}=2.464. Results obtained using the flamelet approaches are compared to data obtained from the detailed solution of the complete transport equations using primitive variables. Numerical simulations of a counterflow flame are also presented to support the discussion of the results. Special emphasis is given to the analysis of the scalar dissipation rate modeling. (author)

  10. Nitrogen and hydrogen CARS temperature measurements in a hydrogen/air flame using a near-adiabatic flat-flame burner

    SciTech Connect (OSTI)

    Hancock, R.D.; Bertagnolli, K.E.; Lucht, R.P.

    1997-05-01

    Coherent anti-Stokes Raman scattering (CARS) spectroscopy of diatomic nitrogen and hydrogen was used to measure flame temperatures in hydrogen/air flames produced using a nonpremixed, near-adiabatic, flat-flame Hencken burner. The CARS temperature measurements are compared with adiabatic flame temperatures calculated by the NASA-Lewis equilibrium code for equivalence ratios from 0.5--2.5. The nitrogen CARS temperatures are in excellent agreement with the equilibrium code calculations. Comparison of nitrogen CARS data and the equilibrium code calculations confirms that for sufficiently high flow rates the Hencken burner produces nearly adiabatic flames. Hydrogen CARS temperature measurements are compared to both nitrogen CARS temperature measurements and equilibrium code predictions in order to evaluate and improve the accuracy of hydrogen CARS as a temperature diagnostic tool. Hydrogen CARS temperatures for fuel-rich flames are on average 70 K ({approximately}3%) above the equilibrium code predictions and nitrogen CARS temperatures. The difference between temperatures measured using hydrogen and nitrogen CARS is probably due primarily to uncertainties in hydrogen linewidths and line-broadening mechanisms at these conditions.

  11. Effects of thermal radiation heat transfer on flame acceleration and transition to detonation in dust cloud flames: Origins of dust explosion

    E-Print Network [OSTI]

    Ivanov, Michael A Liberman M F

    2015-01-01

    We examines regimes of the hydrogen flames propagation and ignition of mixtures heated by the radiation emitted from the flame. The gaseous phase is assumed to be transparent for radiation, while the suspended particles of the dust cloud ahead of the flame absorb and reemit the radiation. The radiant heat absorbed by the particles is then lost by conduction to the surrounding unreacted gaseous phase so that the gas phase temperature lags that of the particles. The direct numerical simulations solve the full system of two phase gas dynamic time-dependent equations with a detailed chemical kinetics for a plane flames propagating through a dust cloud. Depending on the spatial distribution of the dispersed particles and on the value of radiation absorption length the consequence of the radiative preheating of the unreacted mixture can be either the increase of the flame velocity for uniformly dispersed particles or ignition deflagration or detonation ahead of the flame via the Zel'dovich gradient mechanism in the...

  12. Effect of Blending on High-Pressure Laminar Flame Speed Measurements, Markstein Lengths, and Flame Stability of Hydrocarbons 

    E-Print Network [OSTI]

    Lowry, William Baugh

    2012-02-14

    for teaching me what hard work means and how to do it. vi NOMENCLATURE Abbreviations g1855g3043 Specific heat (KJ/kg-K) Di,j Diffusivity of species i into j (m 2/s) g1860 Specific enthalpy (KJ/kg) Le Lewis Number g1865g4662 " Mass... burning rate per unit area (kg/m2-s) g1839g3050 Molecular weight (kg/kmol) X Mole fraction (kmol/kmol) g1851 Mass fraction (kg/kg) Subscripts b Burned condition i For species i L Laminar flame u Unburned condition Superscripts o Un...

  13. Cosmic-Ray Studies with an Alpha Magnetic Spectrometer (AMS Detector) on the International Space Station

    SciTech Connect (OSTI)

    Plyaskin, V.V. [Institute of Theoretical and Experimental Physics, Bol'shaya Cheremushkinskaya ul. 25, Moscow, 117259 (Russian Federation)

    2005-01-01

    A brief description of the physics research program implemented with an alpha magnetic spectrometer (AMS detector) by a large-scale international collaboration on board the International Space Station is presented. The features of the experimental facility under construction are given, along with some results obtained during the test flight of the prototype spectrometer on board a space shuttle.

  14. Understanding and predicting soot generation in turbulent non-premixed jet flames.

    SciTech Connect (OSTI)

    Wang, Hai; Kook, Sanghoon; Doom, Jeffrey; Oefelein, Joseph Charles; Zhang, Jiayao; Shaddix, Christopher R.; Schefer, Robert W.; Pickett, Lyle M.

    2010-10-01

    This report documents the results of a project funded by DoD's Strategic Environmental Research and Development Program (SERDP) on the science behind development of predictive models for soot emission from gas turbine engines. Measurements of soot formation were performed in laminar flat premixed flames and turbulent non-premixed jet flames at 1 atm pressure and in turbulent liquid spray flames under representative conditions for takeoff in a gas turbine engine. The laminar flames and open jet flames used both ethylene and a prevaporized JP-8 surrogate fuel composed of n-dodecane and m-xylene. The pressurized turbulent jet flame measurements used the JP-8 surrogate fuel and compared its combustion and sooting characteristics to a world-average JP-8 fuel sample. The pressurized jet flame measurements demonstrated that the surrogate was representative of JP-8, with a somewhat higher tendency to soot formation. The premixed flame measurements revealed that flame temperature has a strong impact on the rate of soot nucleation and particle coagulation, but little sensitivity in the overall trends was found with different fuels. An extensive array of non-intrusive optical and laser-based measurements was performed in turbulent non-premixed jet flames established on specially designed piloted burners. Soot concentration data was collected throughout the flames, together with instantaneous images showing the relationship between soot and the OH radical and soot and PAH. A detailed chemical kinetic mechanism for ethylene combustion, including fuel-rich chemistry and benzene formation steps, was compiled, validated, and reduced. The reduced ethylene mechanism was incorporated into a high-fidelity LES code, together with a moment-based soot model and models for thermal radiation, to evaluate the ability of the chemistry and soot models to predict soot formation in the jet diffusion flame. The LES results highlight the importance of including an optically-thick radiation model to accurately predict gas temperatures and thus soot formation rates. When including such a radiation model, the LES model predicts mean soot concentrations within 30% in the ethylene jet flame.

  15. "I Miss Green:" A Comparison of Prison and Space Shuttle Design

    E-Print Network [OSTI]

    Kim, Helen

    2011-01-01

    Company, 1985. Print. Peltier, Leonard. Prison Writings: Myrecollections. Leonard Peltier, a Native American prisonergrinding and slamming” (Peltier 6). Jim Lewis, author of New

  16. A rotordynamic analysis of the Space Shuttle Main Engine (SSME) High-Pressure Oxygen Turbopump (HPOTP) 

    E-Print Network [OSTI]

    Moyer, David Scott

    1984-01-01

    engine design philosophy is given by Rothe, '7] while design performance characteristics are listed by Ek ', 3]. The rotating assembly for the HPOTP is illustrated in Fig. 2. This turbopump basically consists of a two-stage centrifugal pump driven by a... and Damping Coefficients at MPL; v = 19, 841 cpm Calculated Boost Impeller Inlet Wear-Ring Damper Seal Stiffness, Damping, and Added-Mass Coefficients Ca)culated Boost Impeller Discharge Wear-Ring Damper Seal Stiffness, Damping, and Added...

  17. "I Miss Green:" A Comparison of Prison and Space Shuttle Design

    E-Print Network [OSTI]

    Kim, Helen

    2011-01-01

    Issue – Rethinking Prison Design. ” NYTimes.com. New YorkPrint. Peltier, Leonard. Prison Writings: My Life is My Sun14 Tannenbaum, Frank. “Prison Cruelty. ” The Atlantic.com.

  18. A Qualitative Model of the Space Shuttle Reaction Control System \\Lambda

    E-Print Network [OSTI]

    Kuipers, Benjamin

    Research Program under grant no. 003658175, and by the Jet Propulsion Laboratory. #12; 1 Introduction as a replacement for one of the main engines in the event of main engine failure and can serve as a fuel dump under, an oxidizer tank, and a set of 14 jets (16 jets for the Forward RCS). Jet usage and firing can be monitored

  19. Fuel Cells Shine a Light on the Last Endeavour Space Shuttle Launch |

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustmentsShirleyEnergyTher i nA Guide to Tapping intoand David To:KamraSackPSTViewsafety,FactDepartment of

  20. Characterization of molecular determinants for nucleocytoplasmic shuttling of PRV UL54

    SciTech Connect (OSTI)

    Li Meili [State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071 (China); Wang Shuai [Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071 (China); Cai Mingsheng; Guo Hong [State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071 (China); Zheng Chunfu, E-mail: zheng.alan@hotmail.com [State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071 (China)

    2011-09-01

    The pseudorabies virus (PRV) early protein UL54 is a homologue of the herpes simplex virus 1 (HSV-1) immediate-early protein ICP27, which is a multifunctional protein and essential for HSV-1 infection. To determine if UL54 might shuttle between the nucleus and cytoplasm, as has been shown for its homologues in human herpesviruses, the molecular determinants for its nucleocytoplasmic shuttling were investigated. Heterokaryon assays demonstrated that UL54 was a nucleocytoplasmic shuttling protein and this property could not be blocked by leptomycin B, an inhibitor of chromosome region maintenance 1 (CRM1). However, TAP/NXF1 promoted the nuclear export of UL54 and interacted with UL54, suggesting that UL54 shuttles between the nucleus and the cytoplasm via a TAP/NXF1, but not CRM1, dependent nuclear export pathway. Furthermore, UL54 was demonstrated to target to the nucleus through a classic Ran-, importin {beta}1- and {alpha}5-dependent nuclear import mechanism.

  1. DIMETHYL ETHER (DME)-FUELED SHUTTLE BUS DEMONSTRATION PROJECT

    SciTech Connect (OSTI)

    Elana M. Chapman; Shirish Bhide; Andre L. Boehman; David Klinikowski

    2003-04-01

    The objectives of this research and demonstration program are to convert a campus shuttle bus to operation on dimethyl ether, a potential ultra-clean alternative diesel fuel. To accomplish this objective, this project includes laboratory evaluation of a fuel conversion strategy, as well as field demonstration of the DME-fueled shuttle bus. Since DME is a fuel with no lubricity (i.e., it does not possess the lubricating quality of diesel fuel), conventional fuel delivery and fuel injection systems are not compatible with dimethyl ether. Therefore, to operate a diesel engine on DME one must develop a fuel-tolerant injection system, or find a way to provide the necessary lubricity to the DME. In this project, they have chosen the latter strategy in order to achieve the objective with minimal need to modify the engine. The strategy is to blend DME with diesel fuel, to obtain the necessary lubricity to protect the fuel injection system and to achieve low emissions. Within the Combustion Laboratory of the Penn State Energy Institute, they have installed and equipped a Navistar V-8 direct-injection turbodiesel engine for measurement of gaseous and particulate emissions and examination of the impact of fuel composition on diesel combustion. They have also reconfigured a high-pressure viscometer for studies of the viscosity, bulk modulus (compressibility) and miscibility of blends of diesel fuel, dimethyl ether and lubricity additives. The results include baseline emissions, performance and combustion measurements on the Navistar engine for operation on a federal low sulfur diesel fuel (300 ppm S). Most recently, they have examined blends of an oxygenated fuel additive (a liquid fuel called CETANER{trademark}) produced by Air Products, for comparison with dimethyl ether blended at the same weight of oxygen addition, 2 wt.%. While they have not operated the engine on DME yet, they are now preparing to do so. A fuel system for delivery of DME/Diesel blends has been configured and initial investigations at low DME blend ratios (around 5-10 vol%) will begin shortly. They have also performed viscosity measurements on diesel fuel, DME and 50-50 blends of DME in diesel. These tests have verified that DME has a much lower viscosity than the diesel fuel and that the viscosity of the blended fuel is also much lower than the diesel base fuel. This has implications for the injection and atomization of the DME/diesel blends.

  2. Laminar round jet diffusion flame buoyant instabilities: Study on the disappearance of varicose structures at ultra-low Froude number

    SciTech Connect (OSTI)

    Boulanger, Joan [Gas Turbine Laboratory, Institute for Aerospace Research, Ottawa, Ontario (Canada)

    2010-04-15

    At very low Froude number, buoyancy instabilities of round laminar jet diffusion flames disappear (except for small tip oscillations referred to as flickering) and those flames look stable and smooth. This study examines the contributions of the different phenomena in the flow dynamics that may explain this effect. It is observed that, at ultra-low Froude/Reynolds numbers, the material influenced by buoyancy is the plume of the flame and not the flame itself (reaction zone) that is short. Therefore, the vorticity creation zone does not profit from the reaction neighbourhood promoting a sharp gradient of density. Expansion and stretch are also important as they push vorticity creation terms more inside the flame and closer to the burner rim compared to moderate Froude flames. In these latter, the vorticity is continuously created around the flame reaction zone, along its developed height and closer to the vertical direction (in average). (author)

  3. Piloted methane/air jet flames : transport effects and aspects of scalar structure.

    SciTech Connect (OSTI)

    Karpetis, Adionos N. (Texas A& M University, College Station, TX); Chen, J. Y. (University of California, Berkeley, CA); Barlow, Robert S.; Frank, Jonathan H.

    2005-02-01

    Previously unpublished results from multiscalar point measurements in the series of piloted CH{sub 4}/air jet flames [R.S. Barlow, J.H. Frank, Proc. Combust. Inst. 27 (1998) 1087-1095] are presented and analyzed. The emphasis is on features of the data that reveal the relative importance of molecular diffusion and turbulent transport in these flames. The complete series A-F is considered. This includes laminar, transitional, and turbulent flames spanning a range in Reynolds number from 1100 to 44,800. Results on conditional means of species mass fractions, the differential diffusion parameter, and the state of the water-gas shift reaction all show that there is an evolution in these flames from a scalar structure dominated by molecular diffusion to one dominated by turbulent transport. Long records of 6000 single-point samples at each of several selected locations in flame D are used to quantify the cross-stream (radial) dependence of conditional statistics of measured scalars. The cross-stream dependence of the conditional scalar dissipation is determined from 6000-shot, line-imaging measurements at selected locations. The cross-stream dependence of reactive scalars, which is most significant in the near field of the jet flame, is attributed to radial differences in both convective and local time scales of the flow. Results illustrate some potential limitations of common modeling assumptions when applied to laboratory-scale flames and, thus, provide a more complete context for interpretation of comparisons between experiments and model calculations.

  4. Piloted methane/air jet flames: Transport effects and aspects of scalar structure

    SciTech Connect (OSTI)

    Barlow, R.S.; Frank, J.H. [Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551-0969 (United States); Karpetis, A.N. [Department of Aerospace Engineering, Texas A and M University, College Station, TX 778453-3141 (United States); Chen, J.-Y. [Mechanical Engineering Department, University of California, Berkeley, CA 94720 (United States)

    2005-12-01

    Previously unpublished results from multiscalar point measurements in the series of piloted CH{sub 4}/air jet flames [R.S. Barlow, J.H. Frank, Proc. Combust. Inst. 27 (1998) 1087-1095] are presented and analyzed. The emphasis is on features of the data that reveal the relative importance of molecular diffusion and turbulent transport in these flames. The complete series A-F is considered. This includes laminar, transitional, and turbulent flames spanning a range in Reynolds number from 1100 to 44,800. Results on conditional means of species mass fractions, the differential diffusion parameter, and the state of the water-gas shift reaction all show that there is an evolution in these flames from a scalar structure dominated by molecular diffusion to one dominated by turbulent transport. Long records of 6000 single-point samples at each of several selected locations in flame D are used to quantify the cross-stream (radial) dependence of conditional statistics of measured scalars. The cross-stream dependence of the conditional scalar dissipation is determined from 6000-shot, line-imaging measurements at selected locations. The cross-stream dependence of reactive scalars, which is most significant in the near field of the jet flame, is attributed to radial differences in both convective and local time scales of the flow. Results illustrate some potential limitations of common modeling assumptions when applied to laboratory-scale flames and, thus, provide a more complete context for interpretation of comparisons between experiments and model calculations.

  5. Highly turbulent counterflow flames: A laboratory scale benchmark for practical systems

    SciTech Connect (OSTI)

    Coppola, Gianfilippo; Coriton, Bruno; Gomez, Alessandro

    2009-09-15

    We propose a highly turbulent counterflow flame as a very useful benchmark of complexity intermediate between laminar flames and practical systems. By operating in a turbulent Reynolds number regime of relevance to practical systems such as gas turbines and internal combustion engines, it retains the interaction of turbulence and chemistry of such environments, but offers several advantages including: (a) the achievement of high Reynolds numbers without pilot flames, which is particularly advantageous from a modeling standpoint; (b) control of the transition from stable flames to local extinction/reignition conditions; (c) compactness of the domain by comparison with jet flames, with obvious advantages from both a diagnostic and, especially, a computational viewpoint; and (d) the reduction or, altogether, elimination of soot formation, thanks to the high strain rates and low residence times of such a system, and the establishment of conditions of large stoichiometric mixture fraction, as required for robust flame stabilization. We demonstrate the phenomenology of such highly strained turbulent flames under conditions spanning unpremixed, partially premixed and premixed regimes. The system lends itself to the validation of DNS and other computational models. It is also well-suited for the examination of practical fuel blends - a need that is becoming more and more pressing in view of the anticipated diversification of the future fossil fuel supply. (author)

  6. Modeling of 1,3-hexadiene, 2,4-hexadiene and 1,4-hexadiene-doped methane flames: Flame modeling, benzene and styrene formation

    SciTech Connect (OSTI)

    Sharma, Sandeep; Harper, Michael R.; Green, William H.

    2010-07-15

    In this work, we have developed a detailed chemical kinetic model and reacting flow simulation for the hexadiene-doped 2-d methane diffusion flames studied experimentally by McEnally and Pfefferle. The GRI-Mech 2.11 methane oxidation and Lawrence Livermore butane oxidation mechanisms were used as the base mechanism to which hexadiene chemistry generated by Reaction Mechanism Generator (RMG) was added. Some important chemically activated pathways leading to aromatic species formation, including the reactions on C{sub 5}H{sub 7}, C{sub 6}H{sub 10}, C{sub 6}H{sub 9}, C{sub 6}H{sub 7}, C{sub 8}H{sub 8} and C{sub 8}H{sub 9} potential energy surfaces, are examined in great detail using quantum chemistry (CBS-QB3) and master equation analysis as implemented in Variflex. An efficient program to solve the doped methane diffusion flame was developed. The solver uses the method of lines to solve the species mass balance equation arising in the diffusion flame. It assumes that the temperature and velocity profiles of the doped flame are the same as those of the undoped flame. The mole fractions of various species as predicted by our model are compared to the experimentally measured mole fractions. The agreement between theory and experiments is quite good for most molecules. The added hexadiene dopants to the flame decompose to produce significant amount of cyclopentadienyl radical, which combines with methyl radical to produce benzene. We also show that styrene is formed primarily by recombination of cyclopentadienyl and propargyl radicals, a pathway which to our knowledge, has not been included in prior flame simulations. (author)

  7. Appearance, temperature, and NO{sub x} emission of two inverse diffusion flames with different port design

    SciTech Connect (OSTI)

    Sze, L.K.; Cheung, C.S.; Leung, C.W.

    2006-01-01

    Experiments were carried out to investigate the appearance, temperature distribution, and NO{sub x} emission index of two inverse diffusion flames, one with circumferentially arranged ports (CAPs) and the other with co-axial (CoA) jets, both burning LPG with 70% butane and 30% propane. Flame appearances were investigated first with a fixed fueling rate at different airflow rates equivalent to air jet Reynolds numbers (Re) of 1000 to 4500; and then at a fixed airflow rate with different fueling rates equivalent to overall equivalence ratios (F) of 1.0 to 2.0. The CAP flame is found to consist of two zones: a lower entrainment zone and an upper mixing and combustion zone. The CoA flame in most cases is similar to a diffusion flame. The two-zone structure can be observed only at Re larger than 2500. The temperature distributions of the flames are similar at overall equivalence ratios of 1.0 and 1.2 for Re=2500, except that the corresponding CoA flame is longer. The flame temperature is higher in the CAP flame than the CoA flame at higher overall equivalence ratios. A measurement of centerline oxygen concentrations shows that the oxygen concentration reaches a minimum value at a flame height of 50 mm in the CAP flame but decreases more gradually in the CoA flame. It can be concluded that there is more intense air-fuel mixing in a CAP flame than the CoA flame. Investigation of the emission index of NO{sub x} (EINO{sub x}) for both flames at Re=2500 and overall equivalence ratios of 1.0 to 6.0 reveals that the EINO{sub x} curve of each flame is bell-shaped, with a maximum value of 3.2 g/kg at F=1.2 for the CAP flame and 3 g/kg at F=2.2 for the CoA flame.

  8. Simulations of flame acceleration and deflagration-to-detonation transitions in methane-air systems

    SciTech Connect (OSTI)

    Kessler, D.A.; Gamezo, V.N.; Oran, E.S. [Laboratory for Computational Physics and Fluid Dynamics, Naval Research Laboratory, Washington, DC (United States)

    2010-11-15

    Flame acceleration and deflagration-to-detonation transitions (DDT) in large obstructed channels filled with a stoichiometric methane-air mixture are simulated using a single-step reaction mechanism. The reaction parameters are calibrated using known velocities and length scales of laminar flames and detonations. Calculations of the flame dynamics and DDT in channels with obstacles are compared to previously reported experimental data. The results obtained using the simple reaction model qualitatively, and in many cases, quantitatively match the experiments and are found to be largely insensitive to small variations in model parameters. (author)

  9. Investigation of critical equivalence ratio and chemical speciation in flames of ethylbenzene-ethanol blends

    SciTech Connect (OSTI)

    Therrien, Richard J.; Ergut, Ali; Levendis, Yiannis A.; Richter, Henning; Howard, Jack B.; Carlson, Joel B.

    2010-02-15

    This work investigates five different one-dimensional, laminar, atmospheric pressure, premixed ethanol/ethylbenzene flames (0%, 25%, 50%, 75% and 90% ethanol by weight) at their soot onset threshold ({phi}{sub critical}). Liquid ethanol/ethylbenzene mixtures were pre-vaporized in nitrogen, blended with an oxygen-nitrogen mixture and, upon ignition, burned in premixed one-dimensional flames at atmospheric pressure. The flames were controlled so that each was at its visual soot onset threshold, and all had similar temperature profiles (determined by thermocouples). Fixed gases, light volatile hydrocarbons, polycyclic aromatic hydrocarbons (PAH), and oxygenated aromatic hydrocarbons were directly sampled at three locations in each flame. The experimental results were compared with a detailed kinetic model, and the modeling results were used to perform a reaction flux analysis of key species. The critical equivalence ratio was observed to increase in a parabolic fashion as ethanol concentration increased in the fuel mixture. The experimental results showed increasing trends of methane, ethane, and ethylene with increasing concentrations of ethanol in the flames. Carbon monoxide was also seen to increase significantly with the increase of ethanol in the flame, which removes carbon from the PAH and soot formation pathways. The PAH and oxygenated aromatic hydrocarbon values were very similar in the 0%, 25% and 50% ethanol flames, but significantly lower in the 75% and 90% ethanol flames. These results were in general agreement with the model and were reflected by the model soot predictions. The model predicted similar soot profiles for the 0%, 25% and 50% ethanol flames, however it predicted significantly lower values in the 75% and 90% ethanol flames. The reaction flux analysis revealed benzyl to be a major contributor to single and double ring aromatics (i.e., benzene and naphthalene), which was identified in a similar role in nearly sooting or highly sooting ethylbenzene flames. The presence of this radical was significantly reduced as ethanol concentration was increased in the flames, and this effect in combination with the lower carbon to oxygen ratios and the enhanced formation of carbon monoxide, are likely what allowed higher equivalence ratios to be reached without forming soot. (author)

  10. Temperature measurement of axisymmetric flames under the influence of magnetic field using Talbot interferometry

    SciTech Connect (OSTI)

    Agarwal, Shilpi, E-mail: sipi.agarwal@gmail.com, E-mail: manojklakra@gmail.com, E-mail: cshakher@iddc.iitd.ac.in; Kumar, Manoj, E-mail: sipi.agarwal@gmail.com, E-mail: manojklakra@gmail.com, E-mail: cshakher@iddc.iitd.ac.in; Shakher, Chandra, E-mail: sipi.agarwal@gmail.com, E-mail: manojklakra@gmail.com, E-mail: cshakher@iddc.iitd.ac.in [Instrument Design Development Centre, Indian Institute of Technology Delhi, HauzKhas, New Delhi - 110016 (India)

    2014-10-15

    Combustion process control is related with ecological improvement and the problem of energy efficiency; hence it has a wide interest at both economical and scientific levels. Application of a magnetic field is one of the most promising methods of combustion control. The presence of magnetic field induces the changes in flame behavior. The effect of uniform magnetic field developed by permanent magnet is studied by Talbot interferometry using circular gratings. Experimental results show a small decrease in flame temperature and increase in flame dimensions.

  11. SuperShuttle CNG Fleet Evaluation--Final Report

    SciTech Connect (OSTI)

    Eudy, L.

    2000-12-07

    The mission of the US Department of Energy's Office of Transportation Technologies is to promote the development and deployment of transportation technologies that reduce US dependence on foreign oil, while helping to improve the nation's air quality and promoting US competitiveness. In support of this mission, DOE has directed the National Renewable Energy Laboratory to conduct projects to evaluate the performance and acceptability of alternative fuel vehicles. NREL has undertaken several fleet study projects, which seek to provide objective real-world fleet experiences with AFVs. For this type of study we collect, analyze, and report on operational, cost, emissions, and performance data from AFVs being driven in a fleet application. The primary purpose of such studies is to make real-world information on AFVs available to fleet managers and other potential AFV purchasers. For this project, data was collected from 13 passenger vans operating in the Boulder/Denver, Colorado area. The study vehicles were all 1999 Ford E-350 passenger vans based at SuperShuttle's Boulder location. Five of the vans were dedicated CNG, five were bi-fuel CNG/gasoline, and three were standard gasoline vans that were used for comparison.

  12. TSTA Piping and Flame Arrestor Operating Experience Data

    SciTech Connect (OSTI)

    Cadwallader, Lee C.; Willms, R. Scott

    2014-10-01

    The Tritium Systems Test Assembly (TSTA) was a facility dedicated to tritium handling technology and experiment research at the Los Alamos National Laboratory. The facility operated from 1984 to 2001, running a prototype fusion fuel processing loop with ~100 grams of tritium as well as small experiments. There have been several operating experience reports written on this facility’s operation and maintenance experience. This paper describes analysis of two additional components from TSTA, small diameter gas piping that handled small amounts of tritium in a nitrogen carrier gas, and the flame arrestor used in this piping system. The operating experiences and the component failure rates for these components are discussed in this paper. Comparison data from other applications are also presented.

  13. FLAME-SAMPLING PHOTOIONIZATION MASS SPECTROSCOPY - FINAL TECHNICAL REPORT

    SciTech Connect (OSTI)

    Hansen, Nils

    2013-02-12

    Research focused on detailed studies of the complex combustion chemistry of oxygenated, bio-derived fuels. In particular, studies were done of the flame chemistry of simple methyl and ethyl esters chosen as surrogates for the long-chain esters that are primary constituents of biodiesel fuels. The principal goals of these studies were: (1) show how fuel-specific structural differences including degree of unsaturation, linear vs. branched chain structures, and methoxy vs. ethoxy functions affect fueldestruction pathways, (2) understand the chemistry leading to potential increases in the emissions of hazardous air pollutants including aldehydes and ketones inherent in the use of biodiesel fuels, and (3) define the key chemical reaction mechanisms responsible for observed reductions in polycyclic aromatic hydrocarbons and particulate matter when oxygenated fuels are used as replacements for conventional fuels.

  14. Experimental study of flame propagation in semiconfined geometries with obstacles

    SciTech Connect (OSTI)

    Urtiew, P.A.; Brandeis, J.; Hogan, W.J.

    1982-02-08

    Accidents in which large quantities of liquefied natural gas (LNG) or other combustible materials are spilled can potentially lead to disastrous consequences, especially if the dispersing combustible cloud finds a suitable ignition source. So far, very little is known about the detailed behavior of a large burning cloud. Full-scale experiments are economically prohibitive, and therefore one must rely on laboratory and field experiments of smaller size, scaling up the results to make predictions about larger spill accidents. In this paper we describe our laboratory-scale experiments with a combustible propane/air mixture in various partially confined geometries. We summarize the experimental results and compare them with calculated results based on numerical simulations of the experiments. Our observations suggest that the geometry of the partial confinement is of primary importance; turbulence-producing obstacles can cause acceleration in the flame front and, more important, can cause a faster burnout of the combustible vapor.

  15. Using phase space attractors to evaluate system safety constraint enforcement : case study in space shuttle mission control procedure rework

    E-Print Network [OSTI]

    Owens, Brandon D. (Brandon Dewain)

    2009-01-01

    As the complexity and influence of engineering systems in modern society increases, so too does their potential to create counterintuitive and catastrophic accidents. Increasingly, the accidents encountered in these systems ...

  16. 16.89/ESD.352 Program Plan Space Systems Engineering Spring 2004 Massachusetts Institute of Technology 1 Dept of Aeronautics and Astronautics, ESD

    E-Print Network [OSTI]

    de Weck, Olivier L.

    ) the completion of the International Space Station (ISS) by 2010, followed by the retirement of the remaining of programs like Apollo, the Space Shuttle or the International Space Station. This raises a number such spacecraft can be launched to Earth orbit without having to develop an entirely new heavy lift launch

  17. THE COMBUSTION OF SOLVENT REPINED COAL IN AN OPPOSED FLOW DIFFUSION FLAME

    E-Print Network [OSTI]

    Chin, W.K.

    2011-01-01

    R.F. (1977). Combustion of coal in an opposed flow diffusionpulverized, solvent-refined coal. ASME Paper No. 76-WA/FU-6.OF SOLVENT REFINED COAL IN AN OPPOSED FLOW DIFFUSION FLAME*

  18. Large eddy simulations of premixed turbulent flame dynamics : combustion modeling, validation and analysis

    E-Print Network [OSTI]

    Kewlani, Gaurav

    2014-01-01

    High efficiency, low emissions and stable operation over a wide range of conditions are some of the key requirements of modem-day combustors. To achieve these objectives, lean premixed flames are generally preferred as ...

  19. Linear and non-linear forced response of a conical, ducted, laminar premixed flame

    SciTech Connect (OSTI)

    Karimi, Nader; Brear, Michael J.; Jin, Seong-Ho; Monty, Jason P. [Department of Mechanical Engineering, University of Melbourne, Parkville, 3010 Vic. (Australia)

    2009-11-15

    This paper presents an experimental study on the dynamics of a ducted, conical, laminar premixed flame subjected to acoustic excitation of varying amplitudes. The flame transfer function is measured over a range of forcing frequencies and equivalence ratios. In keeping with previous works, the measured flame transfer function is in good agreement with that predicted by linear kinematic theory at low amplitudes of acoustic velocity excitation. However, a systematic departure from linear behaviour is observed as the amplitude of the velocity forcing upstream of the flame increases. This non-linearity is mostly in the phase of the transfer function and manifests itself as a roughly constant phase at high forcing amplitude. Nonetheless, as predicted by non-linear kinematic arguments, the response always remains close to linear at low forcing frequencies, regardless of the forcing amplitude. The origin of this phase behaviour is then sought through optical data post-processing. (author)

  20. Sooting Behaviour Dynamics of a Non-Bouyant Laminar Diffusion Flame 

    E-Print Network [OSTI]

    Fuentes, Andres; Legros, Guillaume; Rouvreau, Sebastien; Joulain, Pierre; Vantelon, Jean-Pierre; Torero, Jose L; Fernandez-Pello, Carlos

    2007-01-01

    Local soot concentrations in non-buoyant laminar diffusion flames have been demonstrated to be the outcome of two competitive processes, soot formation and soot oxidation. It was first believed that soot formation was the controlling mechanism...

  1. EFFECTS OF MAGNETIC FIELDS ON THE PROPAGATION OF NUCLEAR FLAMES IN MAGNETIC WHITE DWARFS

    SciTech Connect (OSTI)

    Kutsuna, Masamichi; Shigeyama, Toshikazu [Research Center for the Early Universe, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2012-04-10

    We investigate the effects of the magnetic field on the propagation of laminar flames of nuclear reactions taking place in white dwarfs with masses close to the Chandrasekhar limit. We calculate the velocities of laminar flames parallel and perpendicular to uniform magnetic fields as eigenvalues of steady solutions for magnetic hydrodynamical equations. As a result, we find that even when the magnetic pressure does not dominate the entire pressure it is possible for the magnetic field to suppress the flame propagation through the thermal conduction. Above the critical magnetic field, the flame velocity decreases with increasing magnetic field strength as v {approx} B{sup -1}. In media with densities of 10{sup 7}, 10{sup 8}, and 10{sup 9} g cm{sup -3}, the critical magnetic fields are orders of {approx}10{sup 10}, 10{sup 11}, and 10{sup 12} G, respectively.

  2. Multifractal detrended fluctuation analysis of combustion flames in four-burner impinging entrained-flow gasifier

    E-Print Network [OSTI]

    Niu, Miao-Ren; Yan, Zhuo-Yong; Guo, Qing-Hua; Liang, Qin-Feng; Wang, Fu-Chen; Yu, Zun-Hong

    2007-01-01

    On a laboratory-scale testing platform of impinging entrained-flow gasifier with four opposed burners, the flame images for diesel combustion and gasification process were measured with a single charge coupled device (CCD) camera. The two-dimensional multifractal detrended fluctuation analysis was employed to investigate the multifractal nature of the flame images. Sound power-law scaling in the annealed average of detrended fluctuations was unveiled when the order $q>0$ and the multifractal feature of flame images were confirmed. Further analyses identified two multifractal parameters, the minimum and maximum singularity $\\alpha_{\\min}$ and $\\alpha_{\\max}$, serving as characteristic parameters of the multifractal flames. These two characteristic multifractal parameters vary with respect to different experimental conditions.

  3. The role of secondary char oxidation in the transition from smoldering to flaming 

    E-Print Network [OSTI]

    Putzeys, Olivier; Bar-Ilan, Amnon; Rein, Guillermo; Fernandez-Pello, Carlos; Urban, David

    The transition from forward smoldering to flaming in polyurethane foam is observed using indepth thermocouples and ultrasound probing. The experiments are conducted with small parallelepiped samples vertically placed in ...

  4. Soot Volume Fraction Measurements in a Three-Dimensional Laminar Diffusion Flame established in Microgravity 

    E-Print Network [OSTI]

    Legros, Guillaume; Joulain, Pierre; Jean-Pierre, Vantelon; Fuentes, Andres; Bertheau, Denis; Torero, Jose L

    2005-05-03

    A methodology for the estimation of the soot volume fraction in a three-dimensional laminar diffusion flame is presented. All experiments are conducted in microgravity and have as objective producing quantitative data ...

  5. Three-dimensional numerical simulations of Rayleigh-Taylor unstable flames in type Ia supernovae

    E-Print Network [OSTI]

    Zingale, M.; Woosley, S.E.; Rendleman, C.A.; Day, M.S.; Bell, J.B.

    2005-01-01

    Unstable Flames in Type Ia Supernovae M. Zingale 1 , S. E.Subject headings: supernovae: general — white dwarfs —ame in Type Ia supernovae (SNe Ia) is well recognized (M¨

  6. Rotational and Vibrational Raman Spectroscopy for Thermochemistry Measurements in Supersonic Flames 

    E-Print Network [OSTI]

    Bayeh, Alexander C

    2013-05-31

    , and was inspired by well-known principles of jet combustors. We explored the salient parameters of operation experimentally, and verified flame holding computationally using a well-stirred reactor model. The second stage of the burner generates an external...

  7. The Piloted Transition to Flaming in Smoldering Fire Retarded and Non-Fire Retarded Polyurethane Foam 

    E-Print Network [OSTI]

    Putzeys, Olivier; Fernandez-Pello, Carlos; Rein, Guillermo; Urban, David

    The piloted transition from smoldering to flaming, though a significant fire safety concern, has not been previously extensively studied. Experimental results are presented on the piloted transition from smoldering to ...

  8. Evaluation of the Extinction Factor in a Laminar Flame Established over a PMMA Plate in Microgravity 

    E-Print Network [OSTI]

    Fuentes, Andres; Legros, Guillaume; Joulain, Pierre; Vantelon, Jean-Pierre; Torero, Jose L

    2005-01-01

    A methodology for estimating the extinction factor at wavelength of 530 nm in diffusion flames is presented. All experiments have been in microgravity and have as their objective the production of quantitative data that ...

  9. Layer-by-Layer Nanocoatings with Flame Retardant and Oxygen Barrier Properties: Moving Toward Renewable Systems 

    E-Print Network [OSTI]

    Laufer, Galina 1985-

    2012-10-23

    to cotton fabric, all coated fabrics retained their weave structure after being exposed to a vertical flame test, while uncoated cotton was completely destroyed. Micro combustion calorimetry confirmed that coated fabrics exhibited a reduced peak heat release...

  10. Numerical simulations of perforated plate stabilized premixed flames with detailed chemistry

    E-Print Network [OSTI]

    Kedia, Kushal Sharad

    2010-01-01

    The objective of this work is to develop a high efficiency two-dimensional reactive flow solver to investigate perforated-plate stabilized laminar premixed flames. The developed code is used to examine the impact of the ...

  11. Combustion flame-plasma hybrid reactor systems, and chemical reactant sources

    DOE Patents [OSTI]

    Kong, Peter C

    2013-11-26

    Combustion flame-plasma hybrid reactor systems, chemical reactant sources, and related methods are disclosed. In one embodiment, a combustion flame-plasma hybrid reactor system comprising a reaction chamber, a combustion torch positioned to direct a flame into the reaction chamber, and one or more reactant feed assemblies configured to electrically energize at least one electrically conductive solid reactant structure to form a plasma and feed each electrically conductive solid reactant structure into the plasma to form at least one product is disclosed. In an additional embodiment, a chemical reactant source for a combustion flame-plasma hybrid reactor comprising an elongated electrically conductive reactant structure consisting essentially of at least one chemical reactant is disclosed. In further embodiments, methods of forming a chemical reactant source and methods of chemically converting at least one reactant into at least one product are disclosed.

  12. Studies of n-Propanol, iso-Propanol, and Propane Flames

    SciTech Connect (OSTI)

    Veloo, Peter S.; Egolfopoulos, Fokion N.

    2011-01-01

    The phenomena of propagation and extinction of flames of saturated C{sub 3} alcohols and propane were studied experimentally and numerically in order to assess the effects of the presence and location of the hydroxyl radical in the fuel molecular structure. The experiments were carried out in the counterflow configuration under atmospheric pressure and for unreacted fuel-carrying stream temperature of 343 K. The simulations included detailed descriptions of molecular transport and chemical kinetics using a recently developed kinetic model for C{sub 3} alcohols. The experimental results revealed that the laminar flame speeds and extinction strain rates of n-propanol/air and propane/air flames are close to each other whereas those of iso-propanol/air flames are consistently lower. Similar behavior was observed also for the extinction strain rates of non-premixed n-propanol and iso-propanol flames. It was shown through sensitivity and reaction path analyses that there are two major differences between the intermediates of n-propanol/air and iso-propanol/air flames. In iso-propanol/air flames there are notably higher concentrations of propene whose consumption pathway results in the relatively unreactive allyl radicals, retarding thus the overall reactivity. In n-propanol/air flames there are notably higher concentrations of formaldehyde that reacts readily to form formyl radicals whose subsequent reactions enhance the overall reactivity. The kinetic model used in this study was found to overpredict the experimental results for rich n-propanol/air and propane/air flames. Analysis revealed that those discrepancies are most likely caused by deficiencies in the C{sub 3} alkane kinetics. Through sensitivity analysis, it was determined also that the propagation and extinction of n-propanol/air and iso-propanol/air flames are sensitive largely to hydrogen, carbon monoxide, and C{sub 1}–C{sub 3} kinetics and not to fuel-specific reactions. Finally, the relative sooting propensities of flames of these three fuels were assessed computationally.

  13. EIS-0351: Operation of Flaming Gorge Dam, Colorado River Storage Project, Colorado River, UT

    Broader source: Energy.gov [DOE]

    The Secretary of the United States Department of the Interior (Secretary), acting through the Bureau of Reclamation (Reclamation), is considering whether to implement a proposed action under which Flaming Gorge Dam would be operated to achieve the flow and temperature regimes recommended in the September 2000 report Flow and Temperature Recommendations for Endangered Fishes in the Green River Downstream of Flaming Gorge Dam (2000 Flow and Temperature Recommendations), published by the Upper Colorado River Endangered Fish Recovery Program (Recovery Program).

  14. Soot surface temperature measurements in pure and diluted flames at atmospheric and elevated pressures

    SciTech Connect (OSTI)

    Berry Yelverton, T.L.; Roberts, W.L. [Department of Mechanical and Aerospace Engineering, Campus Box 7910, North Carolina State University, 3211 Broughton Hall, Raleigh, NC 27695 (United States)

    2008-10-15

    Soot surface temperature was measured in laminar jet diffusion flames at atmospheric and elevated pressures. The soot surface temperature was measured in flames at one, two, four, and eight atmospheres with both pure and diluted (using helium, argon, nitrogen, or carbon dioxide individually) ethylene fuels with a calibrated two-color soot pyrometry technique. These two dimensional temperature profiles of the soot aid in the analysis and understanding of soot production, leading to possible methods for reducing soot emission. Each flame investigated was at its smoke point, i.e., at the fuel flow rate where the overall soot production and oxidation rates are equal. The smoke point was chosen because it was desirable to have similar soot loadings for each flame. A second set of measurements were also taken where the fuel flow rate was held constant to compare with earlier work. These measurements show that overall flame temperature decreases with increasing pressure, with increasing pressure the position of peak temperature shifts to the tip of the flame, and the temperatures measured were approximately 10% lower than those calculated assuming equilibrium and neglecting radiation. (author)

  15. Effects of multi-component diffusion and heat release on laminar diffusion flame liftoff

    SciTech Connect (OSTI)

    Li, Zhiliang; Chen, Ruey-Hung [Department of Mechanical, Materials and Aerospace Engineering, University of Central Florida, Orlando, FL 32816-2450 (United States); Phuoc, Tran X. [National Energy Technology Laboratory, Department of Energy, P.O. Box 10940, MS 84-340, Pittsburgh, PA 15261 (United States)

    2010-08-15

    Numerical simulations were conducted of the liftoff and stabilization phenomena of laminar jet diffusion flames of inert-diluted C{sub 3}H{sub 8} and CH{sub 4} fuels. Both non-reacting and reacting jets were investigated, including multi-component diffusivities and heat release effects (buoyancy and gas expansion). The role of Schmidt number for non-reacting jets was investigated, with no conclusive Schmidt number criterion for liftoff previously arrived at in similarity solutions. The cold-flow simulation for He-diluted CH{sub 4} fuel does not predict flame liftoff; however, adding heat release reaction lead to the prediction of liftoff, which is consistent with experimental observations. Including reaction was also found to improve liftoff height prediction for C{sub 3}H{sub 8} flames, with the flame base location differing from that in the similarity solution - the intersection of the stoichiometric and iso-velocity (equal to 1-D flame speed) is not necessary for flame stabilization (and thus liftoff). Possible mechanisms other than that proposed for similarity solution may better help to explain the stabilization and liftoff phenomena. (author)

  16. Autoignited laminar lifted flames of propane in coflow jets with tribrachial edge and mild combustion

    SciTech Connect (OSTI)

    Choi, B.C.; Kim, K.N.; Chung, S.H.

    2009-02-15

    Characteristics of laminar lifted flames have been investigated experimentally by varying the initial temperature of coflow air over 800 K in the non-premixed jets of propane diluted with nitrogen. The result showed that the lifted flame with the initial temperature below 860 K maintained the typical tribrachial structure at the leading edge, which was stabilized by the balance mechanism between the propagation speed of tribrachial flame and the local flow velocity. For the temperature above 860 K, the flame was autoignited without having any external ignition source. The autoignited lifted flames were categorized in two regimes. In the case with tribrachial edge structure, the liftoff height increased nonlinearly with jet velocity. Especially, for the critical condition near blowout, the lifted flame showed a repetitive behavior of extinction and reignition. In such a case, the autoignition was controlled by the non-adiabatic ignition delay time considering heat loss such that the autoignition height was correlated with the square of the adiabatic ignition delay time. In the case with mild combustion regime at excessively diluted conditions, the liftoff height increased linearly with jet velocity and was correlated well with the square of the adiabatic ignition delay time. (author)

  17. Composition PDF/photon Monte Carlo modeling of moderately sooting turbulent jet flames

    SciTech Connect (OSTI)

    Mehta, R.S.; Haworth, D.C.; Modest, M.F. [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States)

    2010-05-15

    A comprehensive model for luminous turbulent flames is presented. The model features detailed chemistry, radiation and soot models and state-of-the-art closures for turbulence-chemistry interactions and turbulence-radiation interactions. A transported probability density function (PDF) method is used to capture the effects of turbulent fluctuations in composition and temperature. The PDF method is extended to include soot formation. Spectral gas and soot radiation is modeled using a (particle-based) photon Monte Carlo method coupled with the PDF method, thereby capturing both emission and absorption turbulence-radiation interactions. An important element of this work is that the gas-phase chemistry and soot models that have been thoroughly validated across a wide range of laminar flames are used in turbulent flame simulations without modification. Six turbulent jet flames are simulated with Reynolds numbers varying from 6700 to 15,000, two fuel types (pure ethylene, 90% methane-10% ethylene blend) and different oxygen concentrations in the oxidizer stream (from 21% O{sub 2} to 55% O{sub 2}). All simulations are carried out with a single set of physical and numerical parameters (model constants). Uniformly good agreement between measured and computed mean temperatures, mean soot volume fractions and (where available) radiative fluxes is found across all flames. This demonstrates that with the combination of a systematic approach and state-of-the-art physical models and numerical algorithms, it is possible to simulate a broad range of luminous turbulent flames with a single model. (author)

  18. Experimental and numerical study of the accuracy of flame-speed measurements for methane/air combustion in a slot burner

    SciTech Connect (OSTI)

    Selle, L.; Ferret, B. [Universite de Toulouse, INPT, UPS, IMFT, Institut de Mecanique des Fluides de Toulouse (France); CNRS, IMFT, Toulouse (France); Poinsot, T. [Universite de Toulouse, INPT, UPS, IMFT, Institut de Mecanique des Fluides de Toulouse (France); CNRS, IMFT, Toulouse (France); CERFACS, Toulouse (France)

    2011-01-15

    Measuring the velocities of premixed laminar flames with precision remains a controversial issue in the combustion community. This paper studies the accuracy of such measurements in two-dimensional slot burners and shows that while methane/air flame speeds can be measured with reasonable accuracy, the method may lack precision for other mixtures such as hydrogen/air. Curvature at the flame tip, strain on the flame sides and local quenching at the flame base can modify local flame speeds and require corrections which are studied using two-dimensional DNS. Numerical simulations also provide stretch, displacement and consumption flame speeds along the flame front. For methane/air flames, DNS show that the local stretch remains small so that the local consumption speed is very close to the unstretched premixed flame speed. The only correction needed to correctly predict flame speeds in this case is due to the finite aspect ratio of the slot used to inject the premixed gases which induces a flow acceleration in the measurement region (this correction can be evaluated from velocity measurement in the slot section or from an analytical solution). The method is applied to methane/air flames with and without water addition and results are compared to experimental data found in the literature. The paper then discusses the limitations of the slot-burner method to measure flame speeds for other mixtures and shows that it is not well adapted to mixtures with a Lewis number far from unity, such as hydrogen/air flames. (author)

  19. Flame structure of wall-impinging diesel fuel sprays injected by group-hole nozzles

    SciTech Connect (OSTI)

    Gao, Jian; Moon, Seoksu; Nishida, Keiya; Matsumoto, Yuhei [Department of Mechanical System Engineering, University of Hiroshima, Higashi-Hiroshima, 739-8527 (Japan); Zhang, Yuyin [Department of Mechanical Engineering, Tokyo Denki University, Tokyo, 101-8457 (Japan)

    2009-06-15

    This paper describes an investigation of the flame structure of wall-impinging diesel sprays injected by group-hole nozzles in a constant-volume combustion vessel at experimental conditions typical of a diesel engine. The particular emphasis was on the effect of the included angle between two orifices (0-15 deg. in current study) on the flame structure and combustion characteristics under various simulated engine load conditions. The laser absorption scattering (LAS) technique was applied to analyze the spray and mixture properties. Direct flame imaging and OH chemiluminescence imaging were utilized to quantify the ignition delay, flame geometrical parameters, and OH chemiluminescence intensity. The images show that the asymmetric flame structure emerges in wall-impinging group-hole nozzle sprays as larger included angle and higher engine load conditions are applied, which is consistent with the spray shape observed by LAS. Compared to the base nozzle, group-hole nozzles with large included angles yield higher overall OH chemiluminescence intensity, wider flame area, and greater proportion of high OH intensity, implying the better fuel/air mixing and improved combustion characteristics. The advantages of group-hole nozzle are more pronounced under high load conditions. Based on the results, the feasibility of group-hole nozzle for practical direct injection diesel engines is also discussed. It is concluded that the asymmetric flame structure of a group-hole nozzle spray is favorable to reduce soot formation over wide engine loads. However, the hole configuration of the group-hole nozzle should be carefully considered so as to achieve proper air utilization in the combustion chamber. Stoichiometric diesel combustion is another promising application of group-hole nozzle. (author)

  20. Methane and methanol oxidation in supercritical water: Chemical kinetics and hydrothermal flame studies

    SciTech Connect (OSTI)

    Steeper, R.R.

    1996-01-01

    Supercritical water oxidation (SCWO) is an emerging technology for the treatment of wastes in the presence of a large concentration of water at conditions above water`s thermodynamic critical point. A high-pressure, optically accessible reaction cell was constructed to investigate the oxidation of methane and methanol in this environment. Experiments were conducted to examine both flame and non-flame oxidation regimes. Optical access enabled the use of normal and shadowgraphy video systems for visualization, and Raman spectroscopy for in situ measurement of species concentrations. Flame experiments were performed by steadily injecting pure oxygen into supercritical mixtures of water and methane or methanol at 270 bar and at temperatures from 390 to 510{degrees}C. The experiments mapped conditions leading to the spontaneous ignition of diffusion flames in supercritical water. Above 470{degrees}C, flames spontaneously ignite in mixtures containing only 6 mole% methane or methanol. This data is relevant to the design and operation of commercial SCWO processes that may be susceptible to inadvertent flame formation. Non-flame oxidation kinetics experiments measured rates of methane oxidation in supercritical water at 270 bar and at temperatures from 390 to 442{degrees}C. The initial methane concentration was nominally 0.15 gmol/L, a level representative of commercial SCWO processes. The observed methane concentration histories were fit to a one-step reaction rate expression indicating a reaction order close to two for methane and zero for oxygen. Experiments were also conducted with varying water concentrations (0 to 8 gmol/L) while temperature and initial reactant concentrations were held constant. The rate of methane oxidation rises steadily with water concentration up to about 5 gmol/L and then abruptly falls off at higher concentrations.

  1. The Shuttle Radar Topography Mission Farr, Tom G., Paul A. Rosen, Edward Caro, Robert Crippen, Riley Duren, Scott Hensley, Michael

    E-Print Network [OSTI]

    1 The Shuttle Radar Topography Mission Farr, Tom G., Paul A. Rosen, Edward Caro, Robert Crippen Barbara, CA Douglas Alsdorf Ohio State University Columbus, OH The Shuttle Radar Topography Mission. The Need for Global Topography At the foundation of modern geosciences, quite literally, is knowledge

  2. Effects of CO addition on the characteristics of laminar premixed CH{sub 4}/air opposed-jet flames

    SciTech Connect (OSTI)

    Wu, C.-Y. [Advanced Engine Research Center, Kao Yuan University, Kaohsiung County, 821 (China); Chao, Y.-C.; Chen, C.-P.; Ho, C.-T. [Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan, 701 (China); Cheng, T.S. [Department of Mechanical Engineering, Chung Hua University, Hsinchu, 300 (China)

    2009-02-15

    The effects of CO addition on the characteristics of premixed CH{sub 4}/air opposed-jet flames are investigated experimentally and numerically. Experimental measurements and numerical simulations of the flame front position, temperature, and velocity are performed in stoichiometric CH{sub 4}/CO/air opposed-jet flames with various CO contents in the fuel. Thermocouple is used for the determination of flame temperature, velocity measurement is made using particle image velocimetry (PIV), and the flame front position is measured by direct photograph as well as with laser-induced predissociative fluorescence (LIPF) of OH imaging techniques. The laminar burning velocity is calculated using the PREMIX code of Chemkin collection 3.5. The flame structures of the premixed stoichiometric CH{sub 4}/CO/air opposed-jet flames are simulated using the OPPDIF package with GRI-Mech 3.0 chemical kinetic mechanisms and detailed transport properties. The measured flame front position, temperature, and velocity of the stoichiometric CH{sub 4}/CO/air flames are closely predicted by the numerical calculations. Detailed analysis of the calculated chemical kinetic structures reveals that as the CO content in the fuel is increased from 0% to 80%, CO oxidation (R99) increases significantly and contributes to a significant level of heat-release rate. It is also shown that the laminar burning velocity reaches a maximum value (57.5 cm/s) at the condition of 80% of CO in the fuel. Based on the results of sensitivity analysis, the chemistry of CO consumption shifts to the dry oxidation kinetics when CO content is further increased over 80%. Comparison between the results of computed laminar burning velocity, flame temperature, CO consumption rate, and sensitivity analysis reveals that the effect of CO addition on the laminar burning velocity of the stoichiometric CH{sub 4}/CO/air flames is due mostly to the transition of the dominant chemical kinetic steps. (author)

  3. The Laminar Flame Speedup by Neon-22 Enrichment in White Dwarf Supernovae

    E-Print Network [OSTI]

    David A. Chamulak; Edward F. Brown; Francis X. Timmes

    2006-12-18

    Carbon-oxygen white dwarfs contain neon-22 formed from alpha-captures onto nitrogen during core He burning in the progenitor star. In a white dwarf (type Ia) supernova, the neon-22 abundance determines, in part, the neutron-to-proton ratio and hence the abundance of radioactive nickel-56 that powers the lightcurve. The neon-22 abundance also changes the burning rate and hence the laminar flame speed. We tabulate the flame speedup for different initial carbon and neon-22 abundances and for a range of densities. This increase in the laminar flame speed--about 30% for a neon-22 mass fraction of 6%--affects the deflagration just after ignition near the center of the white dwarf, where the laminar speed of the flame dominates over the buoyant rise, and in regions of lower density ~ 10^7 g/cm3 where a transition to distributed burning is conjectured to occur. The increase in flame speed will decrease the density of any transition to distributed burning.

  4. Effect of a uniform electric field on soot in laminar premixed ethylene/air flames

    SciTech Connect (OSTI)

    Wang, Y.; Yao, Q. [Key Laboratory of Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, 100084 Beijing (China); Nathan, G.J. [School of Mechanical Engineering, Centre for Energy Technology, The University of Adelaide, S.A. 5005 (Australia); Alwahabi, Z.T.; King, K.D.; Ho, K. [School of Chemical Engineering, Centre for Energy Technology, The University of Adelaide, S.A. 5005 (Australia)

    2010-07-15

    The effect of a nominally uniform electric field on the initially uniform distribution of soot has been assessed for laminar premixed ethylene/air flames from a McKenna burner. An electrophoretic influence on charged soot particles was measured through changes to the deposition rate of soot on the McKenna plug, using laser extinction (LE). Soot volume fraction was measured in situ using laser-induced incandescence (LII). Particle size and morphologies were assessed through ex situ transmission electron microscopy (TEM) using thermophoretic sampling particle diagnostics (TSPD). The results show that the majority of these soot particles are positively charged. The presence of a negatively charged plug was found to decrease the particle residence times in the flame and to influence the formation and oxidation progress. A positively charged plug has the opposite effect. The effect on soot volume fraction, particles size and morphology with electric field strength is also reported. Flame stability was also found to be affected by the presence of the electric field, with the balance of the electrophoretic force and drag force controlling the transition to unstable flame flicker. The presence of charged species generated by the flame was found to reduce the dielectric field strength to one seventh that of air. (author)

  5. Experimental study of Markstein number effects on laminar flamelet velocity in turbulent premixed flames

    SciTech Connect (OSTI)

    Weiss, M.; Zarzalis, N. [Division of Combustion Technology, Engler-Bunte-Institute, University of Karlsruhe (TH), Karlsruhe (Germany); Suntz, R. [Institute for Chemical Technology, University of Karlsruhe (TH), Karlsruhe (Germany)

    2008-09-15

    Effects of turbulent flame stretch on mean local laminar burning velocity of flamelets, u{sub n}, were investigated experimentally in an explosion vessel at normal temperature and pressure. In this context, the wrinkling, A{sub t}/A{sub l}, and the burning velocity, u{sub t}, of turbulent flames were measured simultaneously. With the flamelet assumption the mean local laminar burning velocity of flamelets, u{sub n}=u{sub t} x (A{sub t}/A{sub l}){sup -1}, was calculated for different turbulence intensities. The results were compared to the influence of stretch on spherically expanding laminar flames. For spherically expanding laminar flames the stretched laminar burning velocity, u{sub n}, varied linearly with the Karlovitz stretch factor, yielding Markstein numbers that depend on the mixture composition. Six different mixtures with positive and negative Markstein numbers were investigated. The measurements of the mean local laminar burning velocity of turbulent flamelets were used to derive an efficiency parameter, I, which reflects the impact of the Markstein number and turbulent flame stretch - expressed by the turbulent Karlovitz stretch factor - on the local laminar burning velocity of flamelets. The results showed that the efficiency is reduced with increasing turbulence intensity and the reduction can be correlated to unsteady effects. (author)

  6. Aromatic and polycyclic aromatic hydrocarbon formation in a laminar premixed n-butane flame

    SciTech Connect (OSTI)

    Marinov, N.M.; Pitz, W.J.; Westbrook, C.K.; Vincitore, A.M.; Castaldi, M.J.; Senkan, S.M.; Melius, C.F.

    1998-07-01

    Experimental and detailed chemical kinetic modeling work has been performed to investigate aromatic and polycyclic aromatic hydrocarbon (PAH) formation pathways in a premixed, rich, sooting, n-butane-oxygen-argon burner stabilized flame. An atmospheric pressure, laminar flat flame operated at an equivalence ratio of 2.6 was used to acquire experimental data for model validation. Gas composition analysis was conducted by an on-line gas chromatograph/mass spectrometer technique. Measurements were made in the main reaction and post-reaction zones for a number of low molecular weight species, aliphatics, aromatics, and polycyclic aromatic hydrocarbons (PAHs) ranging from two to five-fused aromatic rings. Reaction flux and sensitivity analysis were used to help identify the important reaction sequences leading to aromatic and PAH growth and destruction in the n-butane flame. Reaction flux analysis showed the propargyl recombination reaction was the dominant pathway to benzene formation. The consumption of propargyl by H atoms was shown to limit propargyl, benzene, and naphthalene formation in flames as exhibited by the large negative sensitivity coefficients. Naphthalene and phenanthrene production was shown to be plausibly formed through reactions involving resonantly stabilized cyclopentadienyl and indenyl radicals. Many of the low molecular weight aliphatics, combustion by-products, aromatics, branched aromatics, and PAHs were fairly well simulated by the model. Additional work is required to understand the formation mechanisms of phenyl acetylene, pyrene, and fluoranthene in the n-butane flame. 73 refs.

  7. Flame Inhibition by Phosphorus-Containing Compounds over a Range of Equivalence Ratios

    SciTech Connect (OSTI)

    Jayaweera, T M; Melius, C F; Pitz, W J; Westbrook, C K; Korobeinichev, O P; Shvartsberg, V M; Shmakov, A G; Rybitskaya, I V; Curran, H

    2004-03-17

    There is much interest in the combustion mechanism of organophosphorus compounds (OPCs) due to their role as potential halon replacements in fire suppression. A continuing investigation of the inhibition activity of organophosphorus compounds under a range of equivalence ratios was performed experimentally and computationally, as measured by the burning velocity. Updates to a previous mechanism were made by the addition and modification of reactions in the mechanism for a more complete description of the recombination reactions. In this work, the laminar flame speed is measured experimentally and calculated numerically for a premixed propane/air flame, under a range of equivalence ratios, undoped and doped with dimethyl methylphosphonate (DMMP). A detailed investigation of the catalytic cycles involved in the recombination of key flame radicals is made for two equivalence ratios, lean and rich. From this, the importance of different catalytic cycles involved in the lean versus rich case is discussed. Although the importance of certain cycles is different under different stoichiometries, the OPCs are similarly effective across the range, demonstrating the robustness of OPCs as flame suppressants. In addition, it is shown that the phosphorus compounds are most active in the high temperature region of the flame. This may, in part, explain their high level of inhibition effectiveness.

  8. In situ flame chemistry tracing by imaging photoelectron photoion coincidence spectroscopy

    SciTech Connect (OSTI)

    Oßwald, P.; Köhler, M.; Hemberger, P.; Bodi, A.; Gerber, T.; Bierkandt, T.; Akyildiz, E.; Kasper, T.

    2014-02-15

    Adaptation of a low-pressure flat flame burner with a flame-sampling interface to the imaging photoelectron photoion coincidence spectrometer (iPEPICO) of the VUV beamline at the Swiss Light Source is presented. The combination of molecular-beam mass spectrometry and iPEPICO provides a new powerful analytical tool for the detailed investigation of reaction networks in flames. First results demonstrate the applicability of the new instrument to comprehensive flame diagnostics and the potentially high impact for reaction mechanism development for conventional and alternative fuels. Isomer specific identification of stable and radical flame species is demonstrated with unrivaled precision. Radical detection and identification is achieved for the initial H-abstraction products of fuel molecules as well as for the reaction controlling H, O, and OH radicals. Furthermore, quantitative evaluation of changing species concentrations during the combustion process and the applicability of respective results for kinetic model validation are demonstrated. Utilization of mass-selected threshold photoelectron spectra is shown to ensure precise signal assignment and highly reliable spatial profiles.

  9. Experimental and modeling investigation of aromatic and polycyclic aromatic hydrocarbon formation in a premixed ethylene flame

    SciTech Connect (OSTI)

    Castaldi, M.J.; Marinov, N.M.; Melius, C.F.

    1996-02-01

    Experimental and detailed chemical kinetic modeling has been performed to investigate aromatic and polyaromatic hydrocarbon formation pathways in a rich, sooting, ethylene-oxygen-argon premixed flame. An atmospheric pressure, laminar flat flame operated at an equivalence ratio of 2.5 was used to acquire experimental data for model validation. Gas composition analysis was conducted by an on-line gas chromatograph/mass spectrometer (GC/MS) technique. Measurements were made in the flame and post-flame zone for a number of low molecular weight species, aliphatics, aromatics and polycyclic aromatic hydrocarbons (PAHs) ranging from two to five-aromatic fused rings. The modeling results show the key reaction sequences leading to aromatic and polycyclic aromatic hydrocarbon growth involve the combination of resonantly stabilized radicals. In particular, propargyl and 1-methylallenyl combination reactions lead to benzene and methyl substituted benzene formation, while polycyclic aromatics are formed from cyclopentadienyl radicals and fused rings that have a shared C{sub 5} side structure. Naphthalene production through the reaction step of cyclopentadienyl self-combination and phenanthrene formation from indenyl and cyclopentadienyl combination were shown to be important in the flame modeling study. The removal of phenyl by O{sub 2} leading to cyclopentadienyl formation is expected to play a pivotal role in the PAH or soot precursor growth process under fuel-rich oxidation conditions.

  10. RESEARCH ARTICLE STEM CELLS AND REGENERATION Nuclear to cytoplasmic shuttling of ERK promotes differentiation of

    E-Print Network [OSTI]

    Klein, Ophir

    RESEARCH ARTICLE STEM CELLS AND REGENERATION Nuclear to cytoplasmic shuttling of ERK promotes disorders. The extracellular signal-regulated kinase 1/2 (ERK) signaling pathway is one of the most molecule (e.g. ERK) can regulate two opposing cellular outcomes is still a mystery. Using both chick

  11. Lawrence Berkeley National Laboratory report LBNL-725E 1 A New Type of Steady and Stable, Laminar, Premixed Flame

    E-Print Network [OSTI]

    Bell, John B.

    Lawrence Berkeley National Laboratory report LBNL-725E 1 A New Type of Steady and Stable, Laminar-air mixtures are found to support another kind of laminar flame that is steady and stable beside flat flames;Nomenclature fuel equivalence ratio 1 Introduction There is growing evidence that a new type of laminar

  12. Effect of Unsaturated Bond on NOx and PAH Formation in nHeptane and 1Heptene Triple Flames

    E-Print Network [OSTI]

    Aggarwal, Suresh K.

    Effect of Unsaturated Bond on NOx and PAH Formation in nHeptane and 1Heptene Triple Flames X. Han of Illinois at Chicago, Chicago, Illinois 60607, United States ABSTRACT: Various engine and shock tube studies flames. NOx formation in the rich premixed zone is primarily due to the prompt NO

  13. Memo: Use of open flames in Biosafety Cabinets/Tissue Culture Hoods From: Ellyn Segal, Ph.D., Biosafety Manager

    E-Print Network [OSTI]

    Kay, Mark A.

    burners or alcohol flames in Biosafety cabinets. The decision has been made in accordance manufacturers. Solutions - Remove Bunsen burners and/or replace with alternative technology such as electric a pilotless burner or touch-plate microburner to provide a flame on demand Contact Ellyn Segal at X5

  14. Soot formation in laminar ethane diffusion flames at pressures from 0.2 to 3.3 MPa

    E-Print Network [OSTI]

    Gülder, Ömer L.

    Soot formation in laminar ethane diffusion flames at pressures from 0.2 to 3.3 MPa Paul M formation and the structure of the temperature field were studied in co-flow ethane-air laminar diffusion; Laminar ethane diffusion flame; Pressure depen- dence of soot formation; Temperature of high

  15. Proceedings of the Combustion Institute, Volume 28, 2000/pp. 903910 TURBULENT FLAME DYNAMICS OF HOMOGENEOUS SOLID PROPELLANT

    E-Print Network [OSTI]

    Apte, Sourabh V.

    luminous flame. The enhanced energy and mass transport in the turbulent region partially merges the primary-eddy-simulation technique. The contribution of large energy-carrying structures to mass, momentum, and energy transfer into the primary flame zone. The turbulence energy spectra indicate dominant harmonics in a frequency range capable

  16. NUMERICAL SIMULATION OF LAMINAR DIFFUSION FLAMES CRAIG C. DOUGLAS \\Lambda , ALEXANDRE ERN y AND MITCHELL D. SMOOKE z

    E-Print Network [OSTI]

    reactions in commercial burners, gas turbines, and ram jets, these flames are important. When modeling flames in which a cylindrical fuel stream is sur­ rounded by a coflowing oxidizer jet is discussed in addition to the temperature and the fluid dynamics variables, is treated. Consider Figure 1. A fuel jet

  17. Chemistry of destroying chemical warfare agents in flame. Technical project report, April 1994-May 1995

    SciTech Connect (OSTI)

    Korobeinichev, O.P.; Chernov, A.A.; Shvartsberg, V.M.; Il`in, S.B.; Mokrushin, V.V.

    1995-05-01

    The goal of the research is to increase our understanding of flame chemistry of organophosphorus compounds (OPC). This class of chemicals includes chemical warfare agents. (CWAs) such as the nerve agents GB GD and VX, stockpiles of which in the United States and Former Soviet Union are scheduled for destruction by incineration or other technologies. Although high CWA destruction efficiency has been demonstrated in incinerator tests in the U.S. it is necessary to improve technology for achievement higher efficiency and lower level of pollutants. The knowledge of detailed destruction chemistry of the CWA and simulants can be obtained by studying the structure of flames, doped with simulants and CWA and by the development of the combustion model which will include the chemical mechanism of destroying CWA in flame. Alkyl phosphates and alkyl phosphonates are typical organophosphorus compounds, that are simulants of sarin.

  18. Non-premixed flame-turbulence interaction in compressible turbulent flow

    SciTech Connect (OSTI)

    Livescu, D. (Daniel); Madnia, C. K.

    2002-01-01

    Nonpremixed turbulent reacting flows are intrinsically difficult to model due to the strong coupling between turbulent motions and reaction. The large amount of heat released by a typical hydrocarbon flame leads to significant modifications of the thermodynamic variables and the molecular transport coefficients and thus alters the fluid dynamics. Additionally, in nonpremixed combustion, the flame has a complex spatial structure. Localized expansions and contractions occur, enhancing the dilatational motions. Therefore, the compressibility of the flow and the heat release are intimately related. However, fundamental studies of the role of compressibility on the scalar mixing and reaction are scarce. In this paper they present results concerning the fundamental aspects of the interaction between non-premixed flame and compressible turbulence.

  19. Detailed modeling and laser-induced fluorescence imaging of nitric oxide in a NH3-seeded non-premixed methane/air flame

    E-Print Network [OSTI]

    Bell, John B.

    non-premixed methane/air flame John B. Bell, Marcus S. Day, Joseph F. Grcar Computing Sciences-induced fluorescence imaging of nitric oxide in a NH3-seeded non-premixed methane/air flame Abstract In this paper we study the formation of NO in laminar, nitrogen diluted methane diffusion flames that are seeded

  20. Kilohertz PIV/PLMS of low-gravity turbulent flames in a drop tower I.G. Boxx, C.A. Idicheria, N.T. Clemens(1)

    E-Print Network [OSTI]

    Clemens, Noel T.

    -flame in a crossflow (JFICF). The system developed represents a major advance in the state of the art of microgravity to examine a hydrogen jet-flame in a crossflow (momentum flux ratio of 7, Re = 900) under normal and low. INTRODUCTION The turbulent jet-flame in a crossflow (JFICF) is a flowfield of theoretical and applied

  1. Mitigation of thermoacoustic instability utilizing steady air injection near the flame anchoring zone

    SciTech Connect (OSTI)

    Murat Altay, H.; Hudgins, Duane E.; Speth, Raymond L.; Annaswamy, Anuradha M.; Ghoniem, Ahmed F.

    2010-04-15

    The objective of this work is to investigate the effectiveness of steady air injection near the flame anchoring zone in suppressing thermoacoustic instabilities driven by flame-vortex interaction mechanism. We perform a systematic experimental study which involves using two different configurations of air injection in an atmospheric pressure backward-facing step combustor. The first configuration utilizes a row of micro-diameter holes allowing for air injection in the cross-stream direction just upstream of the step. The second configuration utilizes an array of micro-diameter holes located on the face of the step, allowing for air injection in the streamwise direction. The effects of each of these configurations are analyzed to determine which one is more effective in suppressing thermoacoustic instabilities at different operating conditions. The tests are conducted while varying the equivalence ratio and the inlet temperature. The secondary air temperature is always the same as the inlet temperature. We used pure propane or propane/hydrogen mixtures as fuels. Combustion dynamics are explored through simultaneous pressure and heat release-rate measurements, and high-speed video images. When the equivalence ratio of the reactant mixture is high, it causes the flame to flashback towards the inlet channel. When air is injected in the cross-stream direction, the flame anchors slightly upstream of the step, which suppresses the instability. When air is injected in the streamwise direction near the edge of step, thermoacoustic instability could be eliminated at an optimum secondary air flow rate, which depends on the operating conditions. When effective, the streamwise air injection prevents the shedding of an unsteady vortex, thus eliminating the flame-vortex interaction mechanism and resulting in a compact, stable flame to form near the step. (author)

  2. Evidence of thermonuclear flame spreading on neutron stars from burst rise oscillations

    SciTech Connect (OSTI)

    Chakraborty, Manoneeta; Bhattacharyya, Sudip E-mail: sudip@tifr.res.in

    2014-09-01

    Burst oscillations during the rising phases of thermonuclear X-ray bursts are usually believed to originate from flame spreading on the neutron star surface. However, the decrease of fractional oscillation amplitude with rise time, which provides a main observational support for the flame spreading model, have so far been reported from only a few bursts. Moreover, the non-detection and intermittent detections of rise oscillations from many bursts are not yet understood considering the flame spreading scenario. Here, we report the decreasing trend of fractional oscillation amplitude from an extensive analysis of a large sample of Rossi X-ray Timing Explorer Proportional Counter Array bursts from 10 neutron star low-mass X-ray binaries. This trend is 99.99% significant for the best case, which provides, to the best of our knowledge, by far the strongest evidence of such a trend. Moreover, it is important to note that an opposite trend is not found in any of the bursts. The concave shape of the fractional amplitude profiles for all the bursts suggests latitude-dependent flame speeds, possibly due to the effects of the Coriolis force. We also systematically study the roles of low fractional amplitude and low count rate for non-detection and intermittent detections of rise oscillations, and attempt to understand them within the flame spreading scenario. Our results support a weak turbulent viscosity for flame spreading, and imply that burst rise oscillations originate from an expanding hot spot, thus making these oscillations a more reliable tool to constrain the neutron star equations of state.

  3. Enhancement of a laminar premixed methane/oxygen/nitrogen flame speed using femtosecond-laser-induced plasma

    SciTech Connect (OSTI)

    Yu Xin; Peng Jiangbo; Yi Yachao; Zhao Yongpeng; Chen Deying; Yu Junhua [National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin 150080 (China); Institute of Opto-electronics, Harbin Institute of Technology, Harbin 150080 (China); Yang Peng; Sun Rui [Institute of Combustion Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2010-07-05

    We first investigate the effects of femtosecond-laser-induced plasma on the flame speed of a laminar premixed methane/oxygen/nitrogen flame with a wide range of the equivalence ratios (0.8-1.05) at atmospheric pressure. It is experimentally found that the flame speed increases 20.5% at equivalence ratios 1.05. The self-emission spectra from the flame and the plasma are studied and an efficient production of active radicals under the action of femtosecond (fs)-laser pulses has been observed. Based on the experimental data obtained, the presence of oxygen atom and hydrocarbon radicals is suggested to be a key factor enhancing flame speed.

  4. Method for producing flame retardant porous products and products produced thereby

    DOE Patents [OSTI]

    Salyer, Ival O. (Dayton, OH)

    1998-08-04

    A method for fire retarding porous products used for thermal energy storage and products produced thereby is provided. The method includes treating the surface of the phase change material-containing porous products with a urea fire-retarding agent. Upon exposure to a flame, the urea forms an adduct with the phase change material which will not sustain combustion (is self-extinguishing) in air. No halogens or metal oxides are contained in the fire retardant, so no potentially noxious halide smoke or fumes are emitted if the product is continuously exposed to a flame.

  5. Method for Producing Flame Retardant Porous Products and Products Produced Thereby

    DOE Patents [OSTI]

    Salyer, Ival O. (Dayton, OH)

    1998-08-04

    A method for fire retarding porous products used for thermal energy storage and products produced thereby is provided. The method includes treating the surface of the phase change material-containing porous products with a urea fire-retarding agent. Upon exposure to a flame, the urea forms an adduct with the phase change material which will not sustain combustion (is self-extinguishing) in air. No halogens or metal oxides are contained in the fire retardant, so no potentially noxious halide smoke or fumes are emitted if the product is continuously exposed to a flame.

  6. Detection of OH in a flame by degenerate four-wave mixing

    SciTech Connect (OSTI)

    Ewart, P.; O'Leary, S.V.

    1986-05-01

    The detection of OH in a laminar premixed air-methane flame by degenerate four-wave mixing (DFWM) is reported. The four-wave mixing spectrum was recorded in the region of the R/sub 1/, R/sub 2/ band heads of the (0, 0) /sup 2/..sigma..-/sup 2/Pi transition, showing clearly resolved rotational structure. Applications of the DFWM technique to combustion diagnostics are discussed. As an example, the distribution of sodium atoms in a sodium-seeded flame has been measured using a 90/sup 0/ geometry to enhance spatial resolution.

  7. Adhesion of diamond coatings synthesized by oxygen-acetylene flame CVD on tungsten carbide

    SciTech Connect (OSTI)

    Marinkovic, S.; Stankovic, S.; Dekanski, A.

    1995-12-31

    The results of a study concerned with chemical vapor deposition of diamond on tungsten carbide cutting tools using an oxygen-acetylene flame in a normal ambient environment are presented. Effects of preparation conditions on the adhesion of the coating have been investigated, including different surface treatment, different position of the flame with respect to the coated surface, effect of an intermediate poorly crystalline diamond layer, etc. In particular, effect of polishing and ultrasonic lapping with diamond powder was compared with that of a corresponding treatment with SiC powder.

  8. A laser and molecular beam mass spectrometer study of low-pressure dimethyl ether flames

    SciTech Connect (OSTI)

    Andrew McIlroy; Toby D. Hain; Hope A. Michelsen; Terrill A. Cool

    2000-12-15

    The oxidation of dimethyl ether (DME) is studied in low-pressure flames using new molecular beam mass spectrometer and laser diagnostics. Two 30.0-Torr, premixed DME/oxygen/argon flames are investigated with stoichiometries of 0.98 and 1.20. The height above burner profiles of nine stable species and two radicals are measured. These results are compared to the detailed chemical reaction mechanism of Curran and coworkers. Generally good agreement is found between the model and data. The largest discrepancies are found for the methyl radical profiles where the model predicts qualitatively different trends in the methyl concentration with stoichiometry than observed in the experiment.

  9. Method for producing flame retardant porous products and products produced thereby

    DOE Patents [OSTI]

    Salyer, I.O.

    1998-08-04

    A method for fire retarding porous products used for thermal energy storage and products produced thereby is provided. The method includes treating the surface of the phase change material-containing porous products with a urea fire-retarding agent. Upon exposure to a flame, the urea forms an adduct with the phase change material which will not sustain combustion (is self-extinguishing) in air. No halogens or metal oxides are contained in the fire retardant, so no potentially noxious halide smoke or fumes are emitted if the product is continuously exposed to a flame. 1 fig.

  10. Investigation on Flame Characteristics and Burner Operability Issues of Oxy-Fuel Combustion

    SciTech Connect (OSTI)

    Choudhuri, Ahsan

    2013-05-30

    Oxy-fuel combustion has been used previously in a wide range of industrial applications. Oxy- combustion is carried out by burning a hydrocarbon fuel with oxygen instead of air. Flames burning in this configuration achieve higher flame temperatures which present opportunities for significant efficiency improvements and direct capture of CO{sub 2} from the exhaust stream. In an effort to better understand and characterize the fundamental flame characteristics of oxy-fuel combustion this research presents the experimental measurements of flame stability of various oxyfuel flames. Effects of H{sub 2} concentration, fuel composition, exhaust gas recirculation ratio, firing inputs, and burner diameters on the flame stability of these fuels are discussed. Effects of exhaust gas recirculation i.e. CO{sub 2} and H{sub 2}O (steam) acting as diluents on burner operability are also presented. The roles of firing input on flame stability are then analyzed. For this study it was observed that many oxy-flames did not stabilize without exhaust gas recirculation due to their higher burning velocities. In addition, the stability regime of all compositions was observed to decrease as the burner diameter increased. A flashback model is also presented, using the critical velocity gradient g{sub F}) values for CH{sub 4}-O{sub 2}-CO{sub 2} flames. The scaling relation (𝐠{sub F} = 𝐜 𝐒{sub 𝐋}{sup 2}/𝛂) for different burner diameters was obtained for various diameter burners. The report shows that results correlated linearly with a scaling value of c =0.0174. The second part of the study focuses on the experimental measurements of the flow field characteristics of premixed CH{sub 4}/21%O{sub 2}/79%N{sub 2} and CH{sub 4}/38%O{sub 2}/72%CO{sub 2} mixtures at constant firing input of 7.5 kW, constant, equivalence ratio of 0.8, constant swirl number of 0.92 and constant Reynolds Numbers. These measurements were taken in a swirl stabilized combustor at atmospheric pressure. The flow field visualization using Particle Imaging Velocimetry (PIV) technique is implemented to make a better understanding of the turbulence characteristics of CH{sub 4}/air and CH{sub 4}/38%O{sub 2}/72%CO{sub 2} combustion. The velocity fluctuations, turbulence intensities and local propagation velocities along the combustion chamber have been determined. The turbulent intensities increase as we move away from the combustor axis. CH{sub 4}-38%O{sub 2}-72%CO{sub 2} flames have low radial velocity and turbulent intensity distributions at different axial distances when compared with CH{sub 4}-Air flames.

  11. The Space of Metric Spaces

    E-Print Network [OSTI]

    *D. J. Kelleher

    2013-11-16

    The Space of Metric Spaces. *D. J. Kelleher1. 1Department of Mathematics. University of Connecticut. UConn— SIGMA Seminar — Fall 2013. D. J. Kelleher.

  12. PHYSICS OF FLUIDS 25, 055107 (2013) Turbulent premixed combustion in V-shaped flames

    E-Print Network [OSTI]

    Gülder, Ömer L.

    2013-01-01

    industrial combustion systems such as, stationary gas turbines, lean premixed and prevaporized jet engines for simulating combustion in gas turbine engines. Second, although a large body of research has been devotedPHYSICS OF FLUIDS 25, 055107 (2013) Turbulent premixed combustion in V-shaped flames

  13. Combustion and Flame 143 (2005) 613628 www.elsevier.com/locate/combustflame

    E-Print Network [OSTI]

    Long, Marshall B.

    2005-01-01

    combustion devices include gas turbines, furnaces, and internal combustion engines. While pre- mixedCombustion and Flame 143 (2005) 613­628 www.elsevier.com/locate/combustflame Soot formation volume fractions, as the fuel fraction increases. 2005 The Combustion Institute. Published by Elsevier

  14. Flame-Retardant Electrical Conductive Nanopolymers Based on Bisphenol F Epoxy Resin Reinforced with Nano Polyanilines

    E-Print Network [OSTI]

    Guo, John Zhanhu

    for obtaining epoxy resin polymer nano- composites (PNCs). The effects of nanofiller morphology and loading The development of conductive or semiconductive polymer nanocomposites (PNCs) from insulating polymers hasFlame-Retardant Electrical Conductive Nanopolymers Based on Bisphenol F Epoxy Resin Reinforced

  15. Chemical structure of a methane counterflow diffusion flame perturbed with the addition

    E-Print Network [OSTI]

    Gomez, Alessandro

    Chemical structure of a methane counterflow diffusion flame perturbed with the addition of either, P.O. Box 208286, New Haven, CT 06520-8286, USA Abstract The chemical structure of a methane is consistent with the anticipated chemical kinetic behavior, based on thermal decomposition of large alkanes

  16. Electric fields effect on liftoff and blowoff of nonpremixed laminar jet flames in a coflow

    SciTech Connect (OSTI)

    Kim, M.K.; Ryu, S.K.; Won, S.H. [School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742 (Korea); Chung, S.H. [Clean Combustion Research Center, King Abdullah University of Science and Technology, Thuwal (Saudi Arabia)

    2010-01-15

    The stabilization characteristics of liftoff and blowoff in nonpremixed laminar jet flames in a coflow have been investigated experimentally for propane fuel by applying AC and DC electric fields to the fuel nozzle with a single-electrode configuration. The liftoff and blowoff velocities have been measured by varying the applied voltage and frequency of AC and the voltage and the polarity of DC. The result showed that the AC electric fields extended the stabilization regime of nozzle-attached flame in terms of jet velocity. As the applied AC voltage increased, the nozzle-attached flame was maintained even over the blowout velocity without having electric fields. In such a case, a blowoff occurred directly without experiencing a lifted flame. While for the DC cases, the influence on liftoff was minimal. There existed three different regimes depending on the applied AC voltage. In the low voltage regime, the nozzle-detachment velocity of either liftoff or blowoff increased linearly with the applied voltage, while nonlinearly with the AC frequency. In the intermediate voltage regime, the detachment velocity decreased with the applied voltage and reasonably independent of the AC frequency. At the high voltage regime, the detachment was significantly influenced by the generation of discharges. (author)

  17. R. Bchela,b, S.E. Pratsinisa, A. Baikerb Two-Nozzle Flame Synthesis of

    E-Print Network [OSTI]

    Daraio, Chiara

    R. Büchela,b, S.E. Pratsinisa, A. Baikerb Two-Nozzle Flame Synthesis of NOx Storage- Reduction and Bioengineering , ETH Zurich, CH-8092 Zurich, Switzerland NOx storage reduction (NSR) catalysts are used) the corresponding light-off Particle production NOx storage and reduction Objective 0 20 40 60 80 100 3) after

  18. Radiation-Driven Flame Spread Over Thermally-Thick Fuels in Quiescent Microgravity Environments

    E-Print Network [OSTI]

    heat transfer from the flame to the fuel bed is negligible. Radiative effects are more significant], the basic approach to modeling Sf is to equate the heat flux per unit area from the gas to the fuel surface Colloquium topic area: 7. Microgravity combustion Keywords: Microgravity-Experiments, Microgravity

  19. Combustion and Flame 153 (2008) 367383 www.elsevier.com/locate/combustflame

    E-Print Network [OSTI]

    Aggarwal, Suresh K.

    2008-01-01

    et al. / Combustion and Flame 153 (2008) 367­383 including CO2, NOx, UHC, and soot. In contrast, hy is formed that propagates upstream along the stoichiometric mixture fraction line with a nearly constant curvature and mixture fraction gra- dient, as well as the hydrodynamic and curvature-induced stretch near

  20. Response of a laminar premixed flame to flow oscillations: A kinematic model and thermoacoustic instability results

    SciTech Connect (OSTI)

    Fleifil, M.; Annaswamy, A.M.; Ghoneim, A.F.; Ghoneim, Z.A.

    1996-09-01

    Combustion instability is a resonance phenomenon that arises due to the coupling between the system acoustics and the unsteady heat release. The constructive feedback between the two processes, which is known to occur as a certain phase relationship between the pressure and the unsteady heat release rate is satisfied, depends on many parameters among which is the acoustic mode, the flame holder characteristics, and the dominant burning pattern. In this paper, the authors construct an analytical model to describe the dynamic response of a laminar premixed flame stabilized on the rim of a tube to velocity oscillation. They consider uniform and nonuniform velocity perturbations superimposed on a pipe flow velocity profile. The model results show that the magnitude of heat release perturbation and its phase with respect to the dynamic perturbation dependent primarily on the flame Strohal number, representing the ratio of the dominant frequency times the tube radius to the laminar burning velocity. In terms of this number, high-frequency perturbations pass through the flame while low frequencies lead to a strong response. The phase with respect to the velocity perturbation behaves in the opposite way. Results of this model are shown to agree with experimental observations and to be useful in determining how the combustion excited model is selected among all the acoustic unstable modes. The model is then used to obtain a time-domain differential equation describing the relationship between the velocity perturbation and the heat release response over the entire frequency range.

  1. Nonlinear self-excited thermoacoustic oscillations of a ducted premixed flame: bifurcations and routes to chaos

    E-Print Network [OSTI]

    Kashinath, Karthik; Waugh, Iain C.; Juniper, Matthew P.

    2014-11-25

    Thermoacoustic systems can oscillate self-excitedly, and often non-periodically, due to coupling between unsteady heat release and acoustic waves. We study a slot-stabilized two-dimensional premixed flame in a duct via numerical simulations of a G...

  2. Combustion and Flame 144 (2006) 426433 www.elsevier.com/locate/combustflame

    E-Print Network [OSTI]

    Gülder, Ömer L.

    2006-01-01

    ,9]. These modeling efforts and comparisons among coflow burners of similar geome- tries require consistent and well mm above the burner rim with the glass ring. In the present study, we investigated the influence detector. The optics were set for 1:1 imaging magnification. The three laminar diffusion flame burners we

  3. Cellular burning in lean premixed turbulent hydrogen-air flames: coupling experimental and

    E-Print Network [OSTI]

    Bell, John B.

    robust and reliable systems difficult to design. Low swirl burners are emerging as an important on a laboratory-scale low swirl burner. The simulations use detailed chemistry and transport without incorporating-flexible burners that can be used to stabilize lean premixed flames in a stationary turbine designed for power

  4. Comparison of structures of laminar methaneoxygen and methaneair diffusion flames from atmospheric to 60 atm

    E-Print Network [OSTI]

    Gülder, Ömer L.

    gradient. The main reactions in this zone were shown to be the oxidation of hydrogen and carbon monoxide Accepted 30 April 2013 Available online 5 June 2013 Keywords: Oxy-fuel combustion Methane­oxygen flames, also promotes the oxidation of soot. Ó 2013 The Combustion Institute. Published by Elsevier Inc. All

  5. Laminar Flame Speed Measurments of Synthetic Gas Blends with Hydrocarbon Impurities 

    E-Print Network [OSTI]

    Keesee, Charles Lewis

    2015-04-09

    New laminar flame speed measurements have been taken for a wide range of synthetic gas, or syngas, mixtures. These experiments began with two baseline mixtures. The first of these baseline mixtures was a bio-syngas surrogate with a 50/50 H2/CO split...

  6. American Institute of Aeronautics and Astronautics Supersonic Combustion and Flame-Holding Characteristics

    E-Print Network [OSTI]

    Texas at Arlington, University of

    American Institute of Aeronautics and Astronautics 1 Supersonic Combustion and Flame engines. For high-speed airflows typical of hypersonic flight, the fuel residence time in the combustor of the combustor length, thus reducing drag and increasing the thrust of a hypersonic vehicle. Recent advances

  7. Carbon dioxide UV laser-induced fluorescence in high-pressure flames

    E-Print Network [OSTI]

    Lee, Tonghun

    Carbon dioxide UV laser-induced fluorescence in high-pressure flames W.G. Bessler a , C. Schulz a; in final form 16 May 2003 Published online 10 June 2003 Abstract Laser-induced fluorescence (LIF) of carbon dioxide is investigated with excitation between 215 and 255 nm with spectrally resolved detection in 5

  8. Solution of Laminar Diffusion Flames Using a Parallel Adaptive Mesh Refinement Algorithm

    E-Print Network [OSTI]

    Groth, Clinton P. T.

    scheme to resolve fine-scale features of laminar flames is demonstrated. I. Introduction Combustion associated with our understanding of and ability to predict combustion phenomena. Over the last 10-15 years, the application of computational fluid dynamics (CFD) methods to reactive flows has yielded an improved

  9. Combustion and Flame 145 (2006) 194205 www.elsevier.com/locate/combustflame

    E-Print Network [OSTI]

    Nicoud, Franck

    2006-01-01

    Combustion and Flame 145 (2006) 194­205 www.elsevier.com/locate/combustflame Joint use swirled burner L. Selle a, , L. Benoit a , T. Poinsot b , F. Nicoud c , W. Krebs d a CERFACS, CFD team, 42 the combustion chamber is not hydrodynamically but acoustically controlled. The two transverse acoustic modes

  10. OH-Planar Fluorescence Measurements of Pressurized, Hydrogen Premixed Flames in the SimVal Combustor

    SciTech Connect (OSTI)

    Strakey, P.A.; Woodruff, S.D.; Williams, T.C.; Schefer, R.W.

    2008-07-01

    Planar laser-induced fluorescence measurements of the hydroxyl radical in lean, premixed natural gas flames augmented with hydrogen are presented. The experiments were conducted in the Simulation Validation combustor at the National Energy Technology Laboratory at operating pressures from 1 to 8 atmospheres. The data, which were collected in a combustor with well-controlled boundary conditions, are intended to be used for validating computational fluid dynamics models under conditions directly relevant to land-based gas turbine engines. The images, which show significant effects of hydrogen on local flame quenching, are discussed in terms of a turbulent premixed combustion regime and nondimensional parameters such as Karlovitz number. Pressure was found to thin the OH region, but only had a secondary effect on overall flame shape compared with the effects of hydrogen addition, which was found to decrease local quenching and shorten the turbulent flame brush. A method to process the individual images based on local gradients of fluorescence intensity is proposed, and results are presented. Finally, the results of several large eddy simulations are presented and compared with the experimental data in an effort to understand the issues related to model validation, especially for simulations that do not include OH as an intermediate species.

  11. Numerical Study of NOx Emissions from n-Heptane and 1-Heptene Counterflow Flames

    E-Print Network [OSTI]

    Aggarwal, Suresh K.

    Numerical Study of NOx Emissions from n-Heptane and 1-Heptene Counterflow Flames Xiao Fu, Stephen that the emissions of CO, NOx, and particulate matter are measurably reduced from biodiesel combustion compared and process used to make the fuel. Consequently, their atomization, combustion, and emission characteristics

  12. Combustion and Flame 145 (2006) 740764 www.elsevier.com/locate/combustflame

    E-Print Network [OSTI]

    Aggarwal, Suresh K.

    2006-01-01

    and numerical investigation of n-heptane/air counterflow partially premixed flames and emission of NOx and PAH.0. The NOx and soot precursor emissions exhibit strong dependence on partial premixing and strain rate, NOx emission is increased due to increased residence time and higher peak temperature. In contrast

  13. A New Supersensitive Flame Detector and its Use for Early Forest Fire Detection

    E-Print Network [OSTI]

    Peskov, Vladimir

    2007-01-01

    A new flame detector, three orders of magnitude more powerful than the existing ones, is presented. This detector needs to be mass-produced for its use in order to be incorporated in an early forest fire detection system. A project able to implement its use to overcome the forest fire emergency is described.

  14. Numerical simulation of Lewis number effects on lean premixed turbulent flames

    E-Print Network [OSTI]

    Bell, John B.

    turbulent flames for lean hydrogen, propane and methane mixtures in two dimensions. Each simulation is broken indicating local extinction. Keywords: turbulent premixed combustion, low Mach number flow for propane, methane and hydrogen using de- tailed chemistry and transport, corresponding to Le > 1, Le 1

  15. High-Pressure Turbulent Flame Speeds and Chemical Kinetics of Syngas Blends with and without Impurities

    SciTech Connect (OSTI)

    Peterson, Eric; Mathieu, Olivier; Morones, Anibal; Ravi, Sankar; Keesee, Charles; Hargis, Joshua; Vivanco, Jose

    2014-12-01

    This Topical Report documents the first year of the project, from October 1, 2013 through September 30, 2014. Efforts for this project included experiments to characterize the atmospheric-pressure turbulent flame speed vessel over a range of operating conditions (fan speeds and turbulent length scales). To this end, a new LDV system was acquired and set up for the detailed characterization of the turbulence field. Much progress was made in the area of impurity kinetics, which included a numerical study of the effect of impurities such as NO2, NO, H2S, and NH3 on ignition delay times and laminar flame speeds of syngas blends at engine conditions. Experiments included a series of laminar flame speed measurements for syngas (CO/H2) blends with various levels of CH4 and C2H6 addition, and the results were compared to the chemical kinetics model of NUI Galway. Also, a final NOx kinetics mechanism including ammonia was assembled, and a journal paper was written and is now in press. Overall, three journal papers and six conference papers related to this project were published this year. Finally, much progress was made on the design of the new high-pressure turbulent flame speed facility. An overall design that includes a venting system was decided upon, and the detailed design is in progress.

  16. Testing of a Hydrogen Diffusion Flame Array Injector at Gas Turbine Conditions

    SciTech Connect (OSTI)

    Weiland, Nathan T.; Sidwell, Todd G.; Strakey, Peter A.

    2013-07-03

    High-hydrogen gas turbines enable integration of carbon sequestration into coal-gasifying power plants, though NO{sub x} emissions are often high. This work explores nitrogen dilution of hydrogen diffusion flames to reduce thermal NO{sub x} emissions and avoid problems with premixing hydrogen at gas turbine pressures and temperatures. The burner design includes an array of high-velocity coaxial fuel and air injectors, which balances stability and ignition performance, combustor pressure drop, and flame residence time. Testing of this array injector at representative gas turbine conditions (16 atm and 1750 K firing temperature) yields 4.4 ppmv NO{sub x} at 15% O{sub 2} equivalent. NO{sub x} emissions are proportional to flame residence times, though these deviate from expected scaling due to active combustor cooling and merged flame behavior. The results demonstrate that nitrogen dilution in combination with high velocities can provide low NO{sub x} hydrogen combustion at gas turbine conditions, with significant potential for further NO{sub x} reductions via suggested design changes.

  17. Combustion and Flame 145 (2006) 128144 www.elsevier.com/locate/combustflame

    E-Print Network [OSTI]

    Im, Hong G.

    2006-01-01

    Combustion and Flame 145 (2006) 128­144 www.elsevier.com/locate/combustflame Direct numerical , Hong G. Im c a Reacting Flow Research Department, Combustion Research Facility, Sandia National with a view to providing better understanding and modeling of combustion processes in homogeneous charge

  18. Combustion and Flame 145 (2006) 390400 www.elsevier.com/locate/combustflame

    E-Print Network [OSTI]

    Im, Hong G.

    2006-01-01

    Combustion and Flame 145 (2006) 390­400 www.elsevier.com/locate/combustflame Extinction characteristics of catalyst-assisted combustion in a stagnation-point flow reactor Jingjing Li, Hong G. Im in catalyst-assisted combustion, numerical simulations of a stagnation-point flow combustor with a catalytic

  19. Demonstration of triple pump coherent anti-Stokes Raman scattering in a jet diffusion flame 

    E-Print Network [OSTI]

    Velur Natarajan, Viswanathan

    2002-01-01

    Three pulsed narrow band pump sources (a frequency doubled pulsed Nd-YAG, and two narrow band dye lasers) and a broad-band Stokes laser source are used to demonstrate triple pump coherent anti-Stokes Raman scattering in a jet diffusion flame...

  20. Effects of radiation and compression on propagating spherical flames of methane/air mixtures near the lean flammability limit

    SciTech Connect (OSTI)

    Chen, Zheng [State Key Laboratory for Turbulence and Complex Systems, Department of Mechanics and Aerospace Engineering, College of Engineering, Peking University, Beijing 100871 (China)

    2010-12-15

    Large discrepancies between the laminar flame speeds and Markstein lengths measured in experiments and those predicted by simulations for ultra-lean methane/air mixtures bring a great concern for kinetic mechanism validation. In order to quantitatively explain these discrepancies, a computational study is performed for propagating spherical flames of lean methane/air mixtures in different spherical chambers using different radiation models. The emphasis is focused on the effects of radiation and compression. It is found that the spherical flame propagation speed is greatly reduced by the coupling between thermal effect (change of flame temperature or unburned gas temperature) and flow effect (inward flow of burned gas) induced by radiation and/or compression. As a result, for methane/air mixtures near the lean flammability limit, the radiation and compression cause large amounts of under-prediction of the laminar flame speeds and Markstein lengths extracted from propagating spherical flames. Since radiation and compression both exist in the experiments on ultra-lean methane/air mixtures reported in the literature, the measured laminar flame speeds and Markstein lengths are much lower than results from simulation and thus cannot be used for kinetic mechanism validation. (author)

  1. Turbulence and combustion interaction: High resolution local flame front structure visualization using simultaneous single-shot PLIF imaging of CH, OH, and CH{sub 2}O in a piloted premixed jet flame

    SciTech Connect (OSTI)

    Li, Z.S.; Li, B.; Sun, Z.W.; Alden, M. [Division of Combustion Physics, Lund University, P.O. Box 118, S-221 00 Lund (Sweden); Bai, X.S. [Division of Fluid Mechanics, Lund University, P.O. Box 118, S-221 00 Lund (Sweden)

    2010-06-15

    High resolution planar laser-induced fluorescence (PLIF) was applied to investigate the local flame front structures of turbulent premixed methane/air jet flames in order to reveal details about turbulence and flame interaction. The targeted turbulent flames were generated on a specially designed coaxial jet burner, in which low speed stoichiometric gas mixture was fed through the outer large tube to provide a laminar pilot flame for stabilization of the high speed jet flame issued through the small inner tube. By varying the inner tube flow speed and keeping the mixture composition as that of the outer tube, different flames were obtained covering both the laminar and turbulent flame regimes with different turbulent intensities. Simultaneous CH/CH{sub 2}O, and also OH PLIF images were recorded to characterize the influence of turbulence eddies on the reaction zone structure, with a spatial resolution of about 40 {mu}m and temporal resolution of around 10 ns. Under all experimental conditions, the CH radicals were found to exist only in a thin layer; the CH{sub 2}O were found in the inner flame whereas the OH radicals were seen in the outer flame with the thin CH layer separating the OH and CH{sub 2}O layers. The outer OH layer is thick and it corresponds to the oxidation zone and post-flame zone; the CH{sub 2}O layer is thin in laminar flows; it becomes broad at high speed turbulent flow conditions. This phenomenon was analyzed using chemical kinetic calculations and eddy/flame interaction theory. It appears that under high turbulence intensity conditions, the small eddies in the preheat zone can transport species such as CH{sub 2}O from the reaction zones to the preheat zone. The CH{sub 2}O species are not consumed in the preheat zone due to the absence of H, O, and OH radicals by which CH{sub 2}O is to be oxidized. The CH radicals cannot exist in the preheat zone due to the rapid reactions of this species with O{sub 2} and CO{sub 2} in the inner-layer of the reaction zones. The local PLIF intensities were evaluated using an area integrated PLIF signal. Substantial increase of the CH{sub 2}O signal and decrease of CH signal was observed as the jet velocity increases. These observations raise new challenges to the current flamelet type models. (author)

  2. NON-SOOTING, LOW FLAME TEMPERATURE MIXING-CONTROLLED DI DIESEL COMBUSTION

    SciTech Connect (OSTI)

    Pickett, L; Siebers, D

    2003-08-24

    Methods of producing non-sooting, low flame temperature diesel combustion were investigated in an optically-accessible, quiescent constant-volume combustion vessel under mixing-controlled diesel combustion conditions. Combustion and soot processes of single, isolated fuel jets were studied after auto-ignition and transient premixed combustion and while the injector was fully-open (i.e. during the mixing-controlled phase of heat release for diesel combustion). The investigation showed that small injector tip orifices could be used to produce non-sooting and low flame temperature combustion simultaneously. The use of small orifices was shown to enable non-sooting and low flame temperature combustion in two different ways as summarized below. A more detailed description of the experimental methods and results is provided in Ref. [1-3]. First, using an injector tip with a 50 micron orifice and ambient oxygen concentrations as low as 10% (simulating the use of extensive EGR), a fuel jet was non-sooting at typical diesel ambient temperatures (1000 K). Second, using the same injector tip at a reduced ambient gas temperature (850 K), but with 21% oxygen, it was shown that non-sooting, mixing-controlled combustion occurred at the lift-off length in a fuel-air mixture with a cross-sectional average equivalence ratio of approximately 0.6-suggesting that the quasi-steady combustion was fuel-lean and thereby avoided the formation of a diffusion flame. The adiabatic flame temperature with reduced ambient oxygen concentration or fuel-lean combustion was approximately 2000 K, compared to typical diesel flame temperatures that exceed 2600 K. The 50 micron orifice results above were obtained using a No.2 diesel fuel. However, using an oxygenated fuel (20 wt% oxygen), the investigation showed that the same low temperature combustion, either with reduced ambient oxygen concentration or fuel-lean combustion, was realized with a 100 micron orifice. Although these single, isolated jets do not have jet-jet interactions that would occur in realistic engines, the results are useful for understanding limiting-case behavior of single-jet mixing and combustion during an injection event. The non-sooting and low flame temperature mixing-controlled combustion realized using small orifice tips suggests that the use of small orifices offers the potential for a simultaneous soot and NOx reduction in an engine, much like diesel HCCI combustion. However, further research is needed to determine whether these methods could be successfully implemented in real engines.

  3. Laminar burning velocities and flame instabilities of butanol isomers-air mixtures

    SciTech Connect (OSTI)

    Gu, Xiaolei; Huang, Zuohua; Wu, Si; Li, Qianqian [State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an 710049 (China)

    2010-12-15

    Laminar burning velocities and flame instabilities of the butanol-air premixed flames and its isomers are investigated using the spherically expanding flame with central ignition at initial temperature of 428 K and initial pressures of 0.10 MPa, 0.25 MPa, 0.50 MPa and 0.75 MPa. Laminar burning velocities and sensitivity factor of n-butanol-air mixtures are computed using a newly developed kinetic mechanism. Unstretched laminar burning velocity, adiabatic temperature, Lewis number, Markstein length, critical flame radius and Peclet number are obtained over a wide range of equivalence ratios. Effect of molecular structure on laminar burning velocity of the isomers of butanol is analyzed from the aspect of C-H bond dissociation energy. Study indicates that although adiabatic flame temperatures of the isomers of butanol are the same, laminar burning velocities give an obvious difference among the isomers of butanol. This indicates that molecular structure has a large influence on laminar burning velocities of the isomers of butanol. Branching (-CH3) will decrease laminar burning velocity. Hydroxyl functional group (-OH) attaching to the terminal carbon atoms gives higher laminar burning velocity compared to that attaching to the inner carbon atoms. Calculated dissociation bond energies show that terminal C-H bonds have larger bond energies than that of inner C-H bonds. n-Butanol, no branching and with hydroxyl functional group (-OH) attaching to the terminal carbon atom, gives the largest laminar burning velocity. tert-Butanol, with highly branching and hydroxyl functional group (-OH) attaching to the inner carbon atom, gives the lowest laminar burning velocity. Laminar burning velocities of iso-butanol and sec-butanol are between those of n-butanol and tert-butanol. The instant of transition to cellularity is experimentally determined for the isomers of butanol and subsequently interpreted on the basis of hydrodynamic and diffusion-thermal instabilities. Little effect on flame instability is observed for the isomers of butanol. Critical flame radii are the same for the isomers of butanol. Peclet number decreases with the increase in equivalence ratio. (author)

  4. Flame-vortex interaction driven combustion dynamics in a backward-facing step combustor

    SciTech Connect (OSTI)

    Altay, H. Murat; Speth, Raymond L.; Hudgins, Duane E.; Ghoniem, Ahmed F.

    2009-05-15

    The combustion dynamics of propane-hydrogen mixtures are investigated in an atmospheric pressure, lean, premixed backward-facing step combustor. We systematically vary the equivalence ratio, inlet temperature and fuel composition to determine the stability map of the combustor. Simultaneous pressure, velocity, heat release rate and equivalence ratio measurements and high-speed video from the experiments are used to identify and characterize several distinct operating modes. When fuel is injected far upstream from the step, the equivalence ratio entering the flame is temporally and spatially uniform, and the combustion dynamics are governed only by flame-vortex interactions. Four distinct dynamic regimes are observed depending on the operating parameters. At high but lean equivalence ratios, the flame is unstable and oscillates strongly as it is wrapped around the large unsteady wake vortex. At intermediate equivalence ratios, weakly oscillating quasi-stable flames are observed. Near the lean blowout limit, long stable flames extending from the corner of the step are formed. At atmospheric inlet temperature, the unstable mode resonates at the 1/4 wavemode of the combustor. As the inlet temperature is increased, the 5/4 wavemode of the combustor is excited at high but lean equivalence ratios, forming the high-frequency unstable flames. Higher hydrogen concentration in the fuel and higher inlet temperatures reduce the equivalence ratios at which the transitions between regimes are observed. We plot combustion dynamics maps or the response curves, that is the overall sound pressure level as a function of the equivalence ratio, for different operating conditions. We demonstrate that numerical results of strained premixed flames can be used to collapse the response curves describing the transitions among the dynamic modes onto a function of the heat release rate parameter alone, rather than a function dependent on the equivalence ratio, inlet temperature and fuel composition separately. We formulate a theory for predicting the critical values of the heat release parameter at which quasi-stable to unstable and unstable to high-frequency unstable modes take place. (author)

  5. Design and Development of a Continuous Precast Prestressed Concrete Bridge System for the Multimodal Freight Shuttle Project 

    E-Print Network [OSTI]

    Parkar, Anagha 1984-

    2011-04-27

    the safety and serviceability of the existing transportation system. The proposed Multimodal Freight Shuttle (MFS) system offers a cost-effective and environmentally friendly method to transport containerized, intercity or port-to-terminal freight...

  6. SuperShuttle CNG Fleet Study Summary: Clean Cities Alternative Fuel Information Series, Alternative Fuel Case Study

    SciTech Connect (OSTI)

    Eudy, L.

    2001-03-05

    An account of the successful use of alternative fuels in a fleet of SuperShuttle passenger vans, which offer shared-rides between Boulder and Denver International Airport.

  7. Explosion bomb measurements of ethanol-air laminar gaseous flame characteristics at pressures up to 1.4 MPa

    SciTech Connect (OSTI)

    Bradley, D.; Lawes, M.; Mansour, M.S. [School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom)

    2009-07-15

    The principal burning characteristics of a laminar flame comprise the fuel vapour pressure, the laminar burning velocity, ignition delay times, Markstein numbers for strain rate and curvature, the stretch rates for the onset of flame instabilities and of flame extinction for different mixtures. With the exception of ignition delay times, measurements of these are reported and discussed for ethanol-air mixtures. The measurements were in a spherical explosion bomb, with central ignition, in the regime of a developed stable, flame between that of an under or over-driven ignition and that of an unstable flame. Pressures ranged from 0.1 to 1.4 MPa, temperatures from 300 to 393 K, and equivalence ratios were between 0.7 and 1.5. It was important to ensure the relatively large volume of ethanol in rich mixtures at high pressures was fully evaporated. The maximum pressure for the measurements was the highest compatible with the maximum safe working pressure of the bomb. Many of the flames soon became unstable, due to Darrieus-Landau and thermo-diffusive instabilities. This effect increased with pressure and the flame wrinkling arising from the instabilities enhanced the flame speed. Both the critical Peclet number and the, more rational, associated critical Karlovitz stretch factor were evaluated at the onset of the instability. With increasing pressure, the onset of flame instability occurred earlier. The measured values of burning velocity are expressed in terms of their variations with temperature and pressure, and these are compared with those obtained by other researchers. Some comparisons are made with the corresponding properties for iso-octane-air mixtures. (author)

  8. A two-step chemical scheme for kerosene-air premixed flames

    SciTech Connect (OSTI)

    Franzelli, B.; Riber, E.; Sanjose, M. [CERFACS, CFD Team, 42 Avenue G. Coriolis, 31057 Toulouse Cedex 01 (France); Poinsot, T. [IMFT-UMR 5502, allee du Professeur Camille Soula, 31400 Toulouse (France)

    2010-07-15

    A reduced two-step scheme (called 2S-KERO-BFER) for kerosene-air premixed flames is presented in the context of Large Eddy Simulation of reacting turbulent flows in industrial applications. The chemical mechanism is composed of two reactions corresponding to the fuel oxidation into CO and H{sub 2}O, and the CO - CO{sub 2} equilibrium. To ensure the validity of the scheme for rich combustion, the pre-exponential constants of the two reactions are tabulated versus the local equivalence ratio. The fuel and oxidizer exponents are chosen to guarantee the correct dependence of laminar flame speed with pressure. Due to a lack of experimental results, the detailed mechanism of Dagaut composed of 209 species and 1673 reactions, and the skeletal mechanism of Luche composed of 91 species and 991 reactions have been used to validate the reduced scheme. Computations of one-dimensional laminar flames have been performed with the 2S{sub K}ERO{sub B}FER scheme using the CANTERA and COSILAB softwares for a wide range of pressure ([1; 12] atm), fresh gas temperature ([300; 700] K), and equivalence ratio ([0.6; 2.0]). Results show that the flame speed is correctly predicted for the whole range of parameters, showing a maximum for stoichiometric flames, a decrease for rich combustion and a satisfactory pressure dependence. The burnt gas temperature and the dilution by Exhaust Gas Recirculation are also well reproduced. Moreover, the results for ignition delay time are in good agreement with the experiments. (author)

  9. All-electrical single-electron shuttle in a silicon quantum dot

    E-Print Network [OSTI]

    Chan, K W; Kemppinen, A; Lai, N S; Tan, K Y; Lim, W H; Dzurak, A S

    2011-01-01

    We report on single-electron shuttling experiments with a silicon metal-oxide-semiconductor quantum dot at 300 mK. Our system consists of an accumulated electron layer at the Si/SiO2 interface below an aluminum top gate with two additional barrier gates used to deplete the electron gas locally and to define a quantum dot. Directional single-electron shuttling from the source and to the drain lead is achieved by applying a dc source-drain bias while driving the barrier gates with an ac voltage of frequency fp. Current plateaus at integer levels of efp are observed up to fp = 240 MHz operation frequencies. The observed results are explained by a sequential tunneling model which suggests that the electron gas may be heated substantially by the ac driving voltage.

  10. Redox Shuttle Additive, Wins 2014 R&D 100 Award | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE: Alternative FuelsofProgram: Report Appendices |ProjectKnowRedox Shuttle Additive, Wins 2014

  11. Flame Dynamics and Structure Within Sub-Millimeter Combustors

    E-Print Network [OSTI]

    of micro-and mesoscale portable heat and power sources, and systems for a myriad of applications,1 of micro- and mesoscale heat sources through development of micro- combustors, engines, heaters) in confined spaces with a large surface-area-to-volume ratio.8,9 Relatively lower temperature devices

  12. Space Kimchi

    E-Print Network [OSTI]

    Hacker, Randi; Oborny, Jaimie; Tsutsui, William

    2006-07-05

    Broadcast Transcript: In space, no one can hear you scream... but did you know that in space no one can detect your smell either? The smell-taste connection means that food in space is not only weightless but tasteless, too. What's a flavor...

  13. A New Type of Steady and Stable, Laminar, Premixed Flame in Ultra-Lean, Hydrogen-Air Combustion

    E-Print Network [OSTI]

    Grcar, Joseph F

    2008-01-01

    for Modeling Steady, Laminar, One-Dimensional PremixedType of Steady and Stable, Laminar, Premixed Flame in Ultra-to support another kind of laminar ?ame that is steady and

  14. The Effects of Charge Motion and Laminar Flame Speed on Late Robust Combustion in a Spark-Ignition Engine

    E-Print Network [OSTI]

    Cheng, Wai K.

    The effects of charge motion and laminar flame speeds on combustion and exhaust temperature have been studied by using an air jet in the intake flow to produce an adjustable swirl or tumble motion, and by replacing the ...

  15. M AT E R I A L S S C I E N C E Making Flame

    E-Print Network [OSTI]

    Blower, Sally

    are typically made by blending traditional poly- mers with flame-retardant phosphorous or halogenated compounds molecular weight be- cause of the physical and chemical differences of the constituent components. Using

  16. Ignition of Deflagration and Detonation Ahead of the Flame due to Radiative Preheating of Suspended Micro Particles

    E-Print Network [OSTI]

    Ivanov, M F; Liberman, M A

    2014-01-01

    We study a flame propagating in the gaseous combustible mixture with suspended inert solid micro particles. The gaseous mixture is assumed to be transparent for thermal radiation emitted by the hot combustion products, while particles absorb and reemit the radiation. Thermal radiation heats the particles, which in turn transfer the heat to the surrounding unburned gaseous mixture by means of thermal heat transfer. Different scenarios are possible depending on the spatial distribution of the particles, their size and the number density. In the case of uniform spatial distribution the radiation absorption ahead of the flame causes a modest increase of the combustion wave velocity. On the contrary, in the case of non-uniform distribution of the particles, such that the particles number density increases far ahead of the flame, the preheating caused by the thermal radiation may trigger additional source of ignition. Far enough ahead of the flame, where number density of particles is higher, the temperature due to...

  17. Proceedings of the Combustion Institute, Volume 29, 2002/pp. 15651572 CHARACTERISTICS OF LIFTED TRIPLE FLAMES STABILIZED IN THE

    E-Print Network [OSTI]

    Aggarwal, Suresh K.

    1565 Proceedings of the Combustion Institute, Volume 29, 2002/pp. 1565­1572 CHARACTERISTICS at their base [2­5]. Chung and Lee [2,3] showed that for non-premixed laminar jets, propane and n- butane flames

  18. A New Type of Steady and Stable, Laminar, Premixed Flame in Ultra-Lean, Hydrogen-Air Combustion

    E-Print Network [OSTI]

    Grcar, Joseph F

    2008-01-01

    411–422. [9] I. Glassman, Combustion, 3rd Edition, AcademicB. Lewis, G. von Elbe, Combustion, Flames and Explosions ofin Ultra-Lean, Hydrogen-Air Combustion Joseph F. Grcar a a

  19. Evolution of soot size distribution in premixed ethylene/air and ethylene/benzene/air flames: Experimental and modeling study

    SciTech Connect (OSTI)

    Echavarria, Carlos A.; Sarofim, Adel F.; Lighty, JoAnn S.; D'Anna, Andrea

    2011-01-15

    The effect of benzene concentration in the initial fuel on the evolution of soot size distribution in ethylene/air and ethylene/benzene/air flat flames was characterized by experimental measurements and model predictions of size and number concentration within the flames. Experimentally, a scanning mobility particle sizer was used to allow spatially resolved and online measurements of particle concentration and sizes in the nanometer-size range. The model couples a detailed kinetic scheme with a discrete-sectional approach to follow the transition from gas-phase to nascent particles and their coagulation to larger soot particles. The evolution of soot size distribution (experimental and modeled) in pure ethylene and ethylene flames doped with benzene showed a typical nucleation-sized (since particles do not actually nucleate in the classical sense particle inception is often used in place of nucleation) mode close to the burner surface, and a bimodal behavior at greater height above burner (HAB). However, major features were distinguished between the data sets. The growth of nucleation and agglomeration-sized particles was faster for ethylene/benzene/air flames, evidenced by the earlier presence of bimodality in these flames. The most significant changes in size distribution were attributed to an increase in benzene concentration in the initial fuel. However, these changes were more evident for high temperature flames. In agreement with the experimental data, the model also predicted the decrease of nucleation-sized particles in the postflame region for ethylene flames doped with benzene. This behavior was associated with the decrease of soot precursors after the main oxidation zone of the flames. (author)

  20. Observations of soot in combustion of methanol/toluene spray flames

    SciTech Connect (OSTI)

    Avedisian, C.T. (Cornell Univ., Ithaca, NY (United States). Sibley School of Mechanical and Aerospace Engineering); Presser, C.; Semerjian, H.G. (National Inst. of Standards and Technology, Gaithersburg, MD (United States). Chemical Science and Technology Lab.); Gupta, A.K. (Maryland Univ., College Park, MD (United States). Dept. of Mechanical Engineering)

    1992-01-01

    The influence of composition on soot formation in spray flames was investigated using, a light scattering/dissymmetry ratio technique to provide information on soot mean size and concentration. The study was carried out using binary mixtures of a sooting (i.e., toluene) and nonsooting (i.e., methanol) liquid. The ranage of mixtures included methanol volume fractions, [alpha], of 0 (i.e., pure toluene), 0.25, 0.50, 0.75, 0.85, 0.90, 0.95, 0.99, and 1.0 (pure methanol). The flames were generated with an air-assist atomizer under the same operating conditions to isolate the effect of liquid composition.

  1. Three-dimensional simulations of cellular non-premixed jet flames

    SciTech Connect (OSTI)

    Valaer, A.L.; Frouzakis, C.E.; Boulouchos, K.; Papas, P.; Tomboulides, A.G.

    2010-04-15

    The formation, dynamics and structure of cellular flames in circular non-premixed jets are examined with three-dimensional numerical simulations incorporating detailed descriptions of chemistry and transport. Similar to past experiments reported in the literature, CO{sub 2}-diluted hydrogen in diluted or pure oxygen co-flowing streams in the proximity of the extinction limit are considered. As in the experiments, several preferred cellular states are found to co-exist with the particular state realized depending on initial conditions as well as on the jet characteristics. The simulations provide additionally the temporal transitions to different stationary or rotating cellular flames, their detailed structure, and the dependence of the scaling of the realized number of cells with the vorticity thickness. (author)

  2. Low and High Temperature Combustion Chemistry of Butanol Isomers in Premixed Flames and Autoignition Systems

    SciTech Connect (OSTI)

    Sarathy, S M; Pitz, W J; Westbrook, C K; Mehl, M; Yasunaga, K; Curran, H J; Tsujimura, T; Osswald, P; Kohse-Hoinghaus, K

    2010-12-12

    Butanol is a fuel that has been proposed as a bio-derived alternative to conventional petroleum derived fuels. The structural isomer in traditional 'bio-butanol' fuel is n-butanol, but newer conversion technologies produce iso-butanol as a fuel. In order to better understand the combustion chemistry of bio-butanol, this study presents a comprehensive chemical kinetic model for all the four isomers of butanol (e.g., 1-, 2-, iso- and tert-butanol). The proposed model includes detailed high temperature and low temperature reaction pathways. In this study, the primary experimental validation target for the model is premixed flat low-pressure flame species profiles obtained using molecular beam mass spectrometry (MBMS). The model is also validated against previously published data for premixed flame velocity and n-butanol rapid compression machine and shock tube ignition delay. The agreement with these data sets is reasonably good. The dominant reaction pathways at the various pressures and temperatures studied are elucidated. At low temperature conditions, we found that the reaction of alphahydroxybutyl with O{sub 2} was important in controlling the reactivity of the system, and for correctly predicting C{sub 4} aldehyde profiles in low pressure premixed flames. Enol-keto isomerization reactions assisted by HO{sub 2} were also found to be important in converting enols to aldehydes and ketones in the low pressure premixed flames. In the paper, we describe how the structural features of the four different butanol isomers lead to differences in the combustion properties of each isomer.

  3. Global modes, receptivity, and sensitivity analysis of diffusion flames coupled with duct

    E-Print Network [OSTI]

    Magri, Luca; Juniper, Matthew P.

    2015-01-01

    . These oscillations are a persistent problem. Their comprehension, prediction and control in the design of gas turbines and rocket engines are areas of current research, as reviewed by Lieuwen & Yang (2005); Culick (2006). This theoretical and numerical paper examines... upstream of the flame, 0 6 x gas state equation: ?1 ?2 = T2T1 = T˜2 T˜1 = 1 + ˜¯Q c˜pT˜1 , (2.5) where ˜¯Q is the steady heat release; c...

  4. Temperature of aircraft cargo flame exposure during accidents involving fuel spills

    SciTech Connect (OSTI)

    Mansfield, J.A.

    1993-01-01

    This report describes an evaluation of flame exposure temperatures of weapons contained in alert (parked) bombers due to accidents that involve aircraft fuel fires. The evaluation includes two types of accident, collisions into an alert aircraft by an aircraft that is on landing or take-off, and engine start accidents. Both the B-1B and B-52 alert aircraft are included in the evaluation.

  5. Effects of swirl-flow on flame propagation in a constant-volume vessel

    SciTech Connect (OSTI)

    Cai, P.; Watanabe, Kazunori; Obara, Tetsuro; Yoshihashi, Teruo; Ohyagi, Shigeharu

    1999-07-01

    Flame propagation in a closed vessel is one of the fundamental topics in the combustion science and technology. This problem has been studied mostly for application to engine combustion because the combustion processes in a premixed spark ignition engine are well simulated by those processes in a constant-volume combustion chamber. One of the most important objective to study this phenomena is to elucidate the combustion phenomena to increase the thermal efficiency of engine by enhancing the combustion process. In real engines, a number of technical methods such as swirl, tumble, squish and jet flows ere developed to shorten a burning time. All of these methods make use of flows in the combustion chamber. The fundamental problem is then to elucidate a mechanism of reduction of the burning time by the flows and their turbulence. In the present work, experiments were conducted to investigate the effects of swirl-flow on the flame propagation in a disc-shaped constant-volume vessel of 100 mm in diameter and 30 mm in depth. Figure A-1 shows a schematic of the apparatus. Gaseous mixtures used were methane diluted with air at an atmospheric pressure, and their equivalence ratios were varied as a parameter. Ignition timing was varied to change the velocity of swirling flow before the flame propagation. As results, a burning time was found to be decreased as the swirling flow increased and a maximum pressure was increased as the velocity increased as a total heat loss decreased. Flame front structures were clearly observed by the instantaneous schlieren photography.

  6. Evidence of thermonuclear flame spreading on neutron stars from burst rise oscillations

    E-Print Network [OSTI]

    Chakraborty, Manoneeta

    2014-01-01

    Burst oscillations during the rising phases of thermonuclear X-ray bursts are usually believed to originate from flame spreading on the neutron star surface. However, the decrease of fractional oscillation amplitude with rise time, which provides a main observational support for the flame spreading model, have so far been reported from only a few bursts. Moreover, the non-detection and intermittent detections of rise oscillations from many bursts are not yet understood considering the flame spreading scenario. Here, we report the decreasing trend of fractional oscillation amplitude from an extensive analysis of a large sample of Rossi X-ray Timing Explorer Proportional Counter Array bursts from ten neutron star low-mass X-ray binaries. This trend is 99.99% significant for the best case, which provides, to the best of our knowledge, by far the strongest evidence of such trend. Moreover, it is important to note that an opposite trend is not found from any of the bursts. The concave shape of the fractional ampli...

  7. Lean methane premixed laminar flames doped by components of diesel fuel II: n-propylcyclohexane

    SciTech Connect (OSTI)

    Pousse, E.; Porter, R.; Warth, V.; Glaude, P.A.; Fournet, R.; Battin-Leclerc, F. [Departement de Chimie-Physique des Reactions, Nancy Universite, CNRS, ENSIC, 1 rue Grandville, BP 20451, 54001 Nancy Cedex (France)

    2010-01-15

    For a better understanding of the chemistry involved during the combustion of components of diesel fuel, the structure of a laminar lean premixed methane flame doped with n-propylcyclohexane has been investigated. The inlet gases contained 7.1% (molar) methane, 36.8% oxygen, and 0.81% n-propylcyclohexane (C{sub 9}H{sub 18}), corresponding to an equivalence ratio of 0.68 and a C{sub 9}H{sub 18}/CH{sub 4} ratio of 11.4%. The flame has been stabilized on a burner at a pressure of 6.7 kPa (50 Torr) using argon as diluent, with a gas velocity at the burner of 49.2 cm/s at 333 K. Quantified species included the usual methane C{sub 0}-C{sub 2} combustion products, but also 17 C{sub 3}-C{sub 5} hydrocarbons, seven C{sub 1}-C{sub 3} oxygenated compounds, and only four cyclic C{sub 6+} compounds, namely benzene, 1,3-cyclohexadiene, cyclohexene, and methylenecyclohexane. A new mechanism for the oxidation of n-propylcyclohexane has been proposed. It allows the proper simulation of profiles of most of the products measured in flames, as well as the satisfactory reproduction of experimental results obtained in a jet-stirred reactor. The main reaction pathways of consumption of n-propylcyclohexane have been derived from rate-of-production analysis. (author)

  8. A lean methane premixed laminar flame doped with components of diesel fuel. I. n-Butylbenzene

    SciTech Connect (OSTI)

    Pousse, E.; Glaude, P.A.; Fournet, R.; Battin-Leclerc, F. [Departement de Chimie-Physique des Reactions, Nancy Universite, CNRS, ENSIC, 1 rue Grandville, BP 20451, 54001 Nancy Cedex (France)

    2009-05-15

    To better understand the chemistry involved in the combustion of components of diesel fuel, the structure of a laminar lean premixed methane flame doped with n-butylbenzene has been investigated. The inlet gases contained 7.1% (molar) methane, 36.8% oxygen, and 0.96% n-butylbenzene corresponding to an equivalence ratio of 0.74 and a ratio C{sub 10}H{sub 14}/CH{sub 4} of 13.5%. The flame has been stabilized on a burner at a pressure of 6.7 kPa using argon as diluent, with a gas velocity at the burner of 49.2 cm/s at 333 K. Quantified species included the usual methane C{sub 0}-C{sub 2} combustion products, but also 16 C{sub 3}-C{sub 5} hydrocarbons, and 7 C{sub 1}-C{sub 3} oxygenated compounds, as well as 20 aromatic products. A new mechanism for the oxidation of n-butylbenzene is proposed whose predictions are in satisfactory agreement with measured species profiles in flames and flow reactor experiments. The main reaction pathways of consumption of n-butylbenzene have been derived from flow rate analyses. (author)

  9. Rich methane laminar flames doped with light unsaturated hydrocarbons. Part II: 1,3butadiene

    E-Print Network [OSTI]

    Gueniche, Hadj-Ali; Fournet, René; Battin-Leclerc, Frédérique

    2007-01-01

    In line with the study presented in the part I of this paper, the structure of a laminar rich premixed methane flame doped with 1,3-butadiene has been investigated. The flame contains 20.7% (molar) of methane, 31.4% of oxygen and 3.3% of 1,3-butadiene, corresponding to an equivalence ratio of 1.8, and a ratio C4H6 / CH4 of 16 %. The flame has been stabilized on a burner at a pressure of 6.7 kPa using argon as dilutant, with a gas velocity at the burner of 36 cm/s at 333 K. The temperature ranged from 600 K close to the burner up to 2150 K. Quantified species included usual methane C0-C2 combustion products and 1,3-butadiene, but also propyne, allene, propene, propane, 1,2-butadiene, butynes, vinylacetylene, diacetylene, 1,3-pentadiene, 2-methyl-1,3-butadiene (isoprene), 1-pentene, 3-methyl-1-butene, benzene and toluene. In order to model these new results, some improvements have been made to a mechanism previously developed in our laboratory for the reactions of C3-C4 unsaturated hydrocarbons. The main reacti...

  10. Rich methane laminar flames doped with light unsaturated hydrocarbons. Part III : cyclopentene

    E-Print Network [OSTI]

    Gueniche, Hadj-Ali; Fournet, René; Battin-Leclerc, Frédérique

    2008-01-01

    In line with the studies presented in the parts I and II of this paper, the structure of a laminar rich premixed methane flame doped with cyclopentene has been investigated. The gases of this flame contains 15.3% (molar) of methane, 26.7% of oxygen and 2.4% cyclopentene corresponding to an equivalence ratio of 1.79 and a ratio C5H8 / CH4 of 16 %. The flame has been stabilized on a burner at a pressure of 6.7 kPa using argon as dilutant, with a gas velocity at the burner of 36 cm/s at 333 K. The temperature ranged from 627 K close to the burner up to 2027 K. Quantified species included usual methane C0-C2 combustion products, but also propyne, allene, propene, propane, 1-butene, 1,3-butadiene, 1,2-butadiene, vinylacetylene, diacetylene, cyclopentadiene, 1,3-pentadiene, benzene and toluene. A new mechanism for the oxidation of cyclopentene has been proposed. The main reaction pathways of consumption of cyclopentene and of formation of benzene and toluene have been derived from flow rate analyses.

  11. Rotational effects in thermonuclear Type I Bursts: equatorial crossing and directionality of flame spreading

    E-Print Network [OSTI]

    Cavecchi, Yuri; Levin, Yuri; Braithwaite, Jonathan

    2014-01-01

    In a previous study on thermonuclear (Type I) Bursts on accreting neutron stars we addressed and demonstrated the importance of the effects of rotation, through the Coriolis force, on the propagation of the burning flame. However, that study only analysed cases of longitudinal propagation, where the Coriolis force coefficient $2\\Omega\\cos\\theta$ was constant. In this paper, we study the effects of rotation on propagation in the meridional (latitudinal) direction, where the Coriolis force changes from its maximum at the poles to zero at the equator. We find that the zero Coriolis force at the equator, while affecting the structure of the flame, does not prevent its propagation from one hemisphere to another. We also observe structural differences between the flame propagating towards the equator and that propagating towards the pole, the second being faster. In the light of the recent discovery of the low spin frequency of burster IGR~J17480-2446 rotating at 11 Hz (for which Coriolis effects should be negligib...

  12. PLIF measurement of fuel concentration distribution in transient hydrogen jet flame

    SciTech Connect (OSTI)

    Tomita, Eiji; Hamamoto, Yoshisuke; Yoshiyama, Sadami; Toda, Hitoshi

    1999-07-01

    To know the concentration field of fuel spray or jet is very important because the following combustion process strongly depends on it. Recently, planar laser induced fluorescence (PLIF) measurement is often used to clarify two-dimensional concentration field of fuel and other species. In this study, PLIF measurement was applied to investigate the concentration distribution of a transient hydrogen jet with combustion. The jet penetrates with entraining ambient air and hydrogen is mixed with the air. Each experimental run of the jet shows different configuration and concentration distribution although averaged jet shows axisymmetric ones. Normalized concentration in radial direction presents Gaussian distribution and normalized concentration in axial direction is expressed by the relation inverse to the axial direction. The mixture was ignited near the nozzle exit after some delay time (t = 3.6ms) during injection ({approximately}11ms). For example, the fuel concentration in the transient jet at t = 1.0 and 1.4ms after the spark ignition (t = 4.6 and 5.0 ms respectively) was obtained as shown in a figure. The behavior of the flame development was measured in the transient flame jet by analyzing these images. The velocities of the jet and flame tips were also determined.

  13. Structure of turbulent hydrogen jet diffusion flames with or without swirl

    SciTech Connect (OSTI)

    Takahashi, Fumiaki; Vangsness, M.D.; Durbin, M.D.; Schmoll, W.J.

    1995-12-31

    The aerodynamic and thermal structure of double-concentric turbulent hydrogen jet diffusion flames with or without swirl has been investigated using three-component laser-Doppler velocimetry (LDV) and coherent anti-Stokes Raman spectroscopy. The LDV data were conditionally sampled upon the origin of the fluid (jet, annulus, or external) to avoid the velocity-bias problem and to gain more detailed information on the turbulent structure. As the mean jet velocity was increased, the turbulent flame zone shifted inward and the thermal layer became thinner, whereas swirl created a radial velocity even at the annulus air exit, thereby shifting the flame zone outward and broadening the thermal layer. The probability-density functions (pdf) of velocity components,m their 21 moments (up to fourth order), temperature pdf, mean, and root-mean-square fluctuation temperature were determined at numerous radial locations at seven axial heights in the near field (<26.5 jet diameters). The data can be used to validate computational models.

  14. Propagation and extinction of premixed C{sub 5}-C{sub 12}n-alkane flames

    SciTech Connect (OSTI)

    Ji, Chunsheng; Dames, Enoch; Wang, Yang L.; Wang, Hai; Egolfopoulos, Fokion N. [Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA 90089-1453 (United States)

    2010-02-15

    Laminar flame speeds and extinction strain rates of premixed C{sub 5}-C{sub 12}n-alkane flames were determined at atmospheric pressure and elevated unburned mixture temperatures, over a wide range of equivalence ratios. Experiments were performed in the counterflow configuration and flow velocities were measured using Laser Doppler Velocimetry. The laminar flame speeds were obtained using a non-linear extrapolation technique utilizing numerical simulations of the counterflow experiments with detailed descriptions of chemical kinetics and molecular transport. Compared to linearly extrapolated values, the laminar flame speeds obtained using non-linear extrapolations were found to be 1-4 cm/s lower depending on the equivalence ratio. It was determined that the laminar flame speeds of all n-alkane/air mixtures considered in this investigation are similar to each other and sensitive largely to the H{sub 2}/CO and C{sub 1}-C{sub 4} hydrocarbon kinetics. Additionally, the resistance to extinction decreases as the fuel molecular weight increases. Simulations of the experiments were performed using the recently developed JetSurF 0.2 reaction model consisting of 194 species and 1459 reactions. The laminar flame speeds were predicted with good accuracy for all the n-alkane-air mixtures considered. The experimental extinction strain rates are well predicted by the model for fuel-lean mixtures. For stoichiometric and fuel-rich mixtures, the predicted extinction strain rates are approximately 10% lower than the experimental values. Insights into the physical and chemical processes that control the response of n-alkane flames are provided through detailed sensitivity analyses on both reaction rates and binary diffusion coefficients. (author)

  15. Influence of a combustion-driven oscillation on global mixing in the flame from a refinery flare

    SciTech Connect (OSTI)

    Langman, A.S.; Nathan, G.J.

    2011-01-15

    An assessment of the influence of strong combustion-driven oscillations on mixing rates and visible radiation in the flame from a full-scale refinery flare is reported. Importantly, the oscillations were generated naturally, with no external forcing, and at a high Reynolds number of 4 x 10{sup 6}. These conditions differentiate this study from those of previous investigations, which all involved some external forcing and were at a Re too low to ensure fully turbulent flow within the flame. A frame-by-frame analysis of video footage, providing good resolution of the instantaneous edge of each flame, was used to assess flame dimensions, and so to determine a global residence time. Since the flames are in the fast-chemistry regime, the visual imagers can be used to determine a global mixing rate. The analysis reveals a consistent picture that the combustion-driven oscillations do not result in a significant change to the global mixing rate, but do increase the visible radiation. This is in contrast to previous investigations, using externally forced jets, where forcing at the preferred mode has been found to increase mixing rates and reduce radiation. (author)

  16. On the influence of singlet oxygen molecules on the speed of flame propagation in methane-air mixture

    SciTech Connect (OSTI)

    Starik, A.M.; Kozlov, V.E.; Titova, N.S. [P. I. Baranov Central Institute of Aviation Motors, Moscow (Russian Federation)

    2010-02-15

    The effect of the presence of singlet oxygen molecules O{sub 2}(a{sup 1}{delta}{sub g}) in a CH{sub 4}-air mixture on the speed of laminar flame propagation is considered. The known experimental data on the laminar flame speed and ignition delay are used to validate the developed kinetic model involving electronically excited oxygen molecules O{sub 2}(a{sup 1}{delta}{sub g}) and O{sub 2}(b{sup 1}{sigma}{sub g}{sup +}). Numerical simulation shows that the presence of 10% O{sub 2}(a{sup 1}{delta}{sub g}) in molecular oxygen enables to increase significantly (by a factor of 1.7) the speed of flame propagation in a fuel-lean ({phi}=0.45) methane-air mixture. The main reason for such an acceleration of flame propagation is the intensification of chain reactions due to addition of singlet delta oxygen molecules. For a fuel-rich mixture ({phi}=1.9), the growth in the flame speed is significantly smaller and attains a factor of 1.4. (author)

  17. A Study of Strain Rate Effects for Turbulent Premixed Flames with Application to LES of a Gas Turbine Combustor Model

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kemenov, Konstantin A.; Calhoon, William H.

    2015-03-24

    Large-scale strain rate field, a resolved quantity which is easily computable in large-eddy simulations (LES), could have profound effects on the premixed flame properties by altering the turbulent flame speed and inducing local extinction. The role of the resolved strain rate has been investigated in a posterior LES study of GE lean premixed dry low NOx emissions LM6000 gas turbine combustor model. A novel approach which is based on the coupling of the lineareddy model with a one-dimensional counter-flow solver has been applied to obtain the parameterizations of the resolved premixed flame properties in terms of the reactive progress variable,more »the local strain rate measure, and local Reynolds and Karlovitz numbers. The strain rate effects have been analyzed by comparing LES statistics for several models of the turbulent flame speed, i.e, with and without accounting for the local strain rate effects, with available experimental data. The sensitivity of the simulation results to the inflow velocity conditions as well as the grid resolution have been also studied. Overall, the results suggest the necessity to represent the strain rate effects accurately in order to improve LES modeling of the turbulent flame speed.« less

  18. Determination, correlation, and mechanistic interpretation of effects of hydrogen addition on laminar flame speeds of hydrocarbon–air mixtures

    SciTech Connect (OSTI)

    Tang, C. L.; Huang, Z. H.; Law, C. K.

    2010-08-30

    The stretch-affected propagation speeds of expanding spherical flames of n-butane–air mixtures with hydrogen addition were measured at atmospheric pressure and subsequently processed through a nonlinear regression analysis to yield the stretch-free laminar flame speeds. Based on a hydrogen addition parameter (RH) and an effective fuel equivalence ratio (?F), these laminar flame speeds were found to increase almost linearly with RH, for ?F between 0.6 and 1.4 and RHRH from 0 to 0.5, with the slope of the variation assuming a minimum around stoichiometry. These experimental results also agree well with computed values using a detailed reaction mechanism. Furthermore, a mechanistic investigation aided by sensitivity analysis identified that kinetic effects through the global activation energy, followed by thermal effects through the adiabatic flame temperature, have the most influence on the increase in the flame speeds and the associated linear variation with RH due to hydrogen addition. Nonequidiffusion effects due to the high mobility of hydrogen, through the global Lewis number, have the least influence. Further calculations for methane, ethene, and propane as the fuel showed similar behavior, leading to possible generalization of the phenomena and correlation.

  19. A Study of Strain Rate Effects for Turbulent Premixed Flames with Application to LES of a Gas Turbine Combustor Model

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kemenov, Konstantin A.; Calhoon, William H.

    2015-03-24

    Large-scale strain rate field, a resolved quantity which is easily computable in large-eddy simulations (LES), could have profound effects on the premixed flame properties by altering the turbulent flame speed and inducing local extinction. The role of the resolved strain rate has been investigated in a posterior LES study of GE lean premixed dry low NOx emissions LM6000 gas turbine combustor model. A novel approach which is based on the coupling of the lineareddy model with a one-dimensional counter-flow solver has been applied to obtain the parameterizations of the resolved premixed flame properties in terms of the reactive progress variable, the local strain rate measure, and local Reynolds and Karlovitz numbers. The strain rate effects have been analyzed by comparing LES statistics for several models of the turbulent flame speed, i.e, with and without accounting for the local strain rate effects, with available experimental data. The sensitivity of the simulation results to the inflow velocity conditions as well as the grid resolution have been also studied. Overall, the results suggest the necessity to represent the strain rate effects accurately in order to improve LES modeling of the turbulent flame speed.

  20. Effects of Turbulence on the Combustion Properties of Partially Premixed Flames of Canola Methyl Ester and Diesel Blends

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Dhamale, N.; Parthasarathy, R. N.; Gollahalli, S. R.

    2011-01-01

    Canola methyl ester (CME) is a biofuel that is a renewable alternative energy resource and is produced by the transesterification of canola oil. The objective of this study was to document the effects of turbulence on the combustion characteristics of blends of CME and No 2 diesel fuel in a partially-premixed flame environment. The experiments were conducted with mixtures of pre-vaporized fuel and air at an initial equivalence ratio of 7 and three burner exit Reynolds numbers, 2700, 3600, and 4500. Three blends with 25, 50, and 75% volume concentration of CME were studied. The soot volume fraction was highestmore »for the pure diesel flames and did not change significantly with Reynolds number due to the mutually compensating effects of increased carbon input rate and increased air entrainment as the Reynolds number was increased. The global NOx emission index was highest and the CO emission index was the lowest for the pure CME flame, and varied non-monotonically with biofuel content in the blend The mean temperature and the NOx concentration at three-quarter flame height were generally correlated, indicating that the thermal mechanism of NOx formation was dominant in the turbulent biofuel flames also.« less

  1. A role of chemical kinetics in the simulation of the reaction kernel of methane jet diffusion flames

    SciTech Connect (OSTI)

    Takahashi, Fumiaki; Katta, V.R.

    1999-07-01

    The detailed structure of the stabilizing region of an axisymmetric laminar methane jet diffusion flame has been studied numerically. Computations using a time-dependent, implicit, third-order accurate numerical scheme with buoyancy effects were performed using two different C{sub 2}-chemistry models and compared with the previous results using a C{sub 1}-chemistry model. The results were nearly identical for all kinetic models except that the C{sub 1}-chemistry model over-predicted the methyl-radical and formaldehyde concentrations on the fuel side of the flame and that the standoff distance of the flame base from the burner rim varied. The standoff distance was sensitive to the CH{sub 3} + H + (M) {yields} CH{sub 4} + (M) reaction. The highest reactivity spot (reaction kernel) was formed in the relatively low-temperature (<1,600 K) flame base, where the CH{sub 3} + O {yields} CH{sub 2}O + H reaction predominantly contributed to the heat release, providing a stationary ignition source to incoming reactants and thereby stabilizing the trailing diffusion flame.

  2. Combustion characteristics of pulverized coal and air/gas premixed flame in a double swirl combustor

    SciTech Connect (OSTI)

    Kamal, M.M.

    2009-07-01

    An experimental work was performed to investigate the co-firing of pulverized coal and premixed gas/air streams in a double swirl combustor. The results showed that the NOx emissions are affected by the relative rates of thermal NOx formation and destruction via the pyrolysis of the fuel-N species in high temperature fuel-rich zones. Various burner designs were tested in order to vary the temperature history and the residence time across both coal and gas flames inside the furnace. It was found that by injecting the coal with a gas/air mixture as a combined central jet surrounded by a swirled air stream, a double flame envelope develops with high temperature fuel-rich conditions in between the two reaction zones such that the pyrolysis reactions to N{sub 2} are accelerated. A further reduction in the minimum NOx emissions, as well as in the minimum CO concentrations, was reported for the case where the coal particles are fed with the gas/air mixture in the region between the two swirled air streams. On the other hand, allocating the gas/air mixture around the swirled air-coal combustion zone provides an earlier contact with air and retards the NOx reduction mechanism in such a way that the elevated temperatures around the coal particles allow higher overall NOx emissions. The downstream impingement of opposing air jets was found more efficient than the impinging of particle non-laden premixed flames for effective NOx reduction. In both cases, there is an upstream flow from the stagnation region to the coal primary combustion region, but with the case of air impingement, the hot fuel-rich zone develops earlier. The optimum configuration was found by impinging all jets of air and coal-gas/air mixtures that pronounced minimum NOx and CO concentrations of 310 and 480ppm, respectively.

  3. The effect of acoustics on an ethanol spray flame in a propane-fired pulse combustor

    SciTech Connect (OSTI)

    Dubey, R.K.; Black, D.L.; McQuay, M.Q. [Brigham Young Univ., Provo, UT (United States). Mechanical Engineering Dept.] [Brigham Young Univ., Provo, UT (United States). Mechanical Engineering Dept.; Carvalho, J.A. Jr. [Inst. Nacional de Pesquisas Espaciais, Cachoeira Paulista, Sao Paulo (Brazil). Lab. Associado de Comubustao e Propulsao] [Inst. Nacional de Pesquisas Espaciais, Cachoeira Paulista, Sao Paulo (Brazil). Lab. Associado de Comubustao e Propulsao

    1997-07-01

    The influence of an acoustic field on the combustion characteristics of a hydrogen-stabilized ethanol spray flame has been experimentally investigated using a phase-Doppler particle analyzer in a propane-fired, Rijke-tube, pulse combustor. The controlled sinusoidal acoustic field in the combustor had a sound pressure level of 155 dB and a frequency of 80 Hz. Experiments were performed to study the effect of oscillations on Sauter-mean and arithmetic-mean diameters, droplet velocity, and droplet number density for the present operating conditions of the Rijke-tube combustor. Similar measurements were also performed on a water spray in the propane-fired reactor to study the effect of the acoustic field on the atomization process for the nozzle type used. Spectral analysis of the droplet axial velocity component for the oscillating conditions revealed a dominant frequency equal to the frequency of the sinusoidal acoustic wave in the combustor. The Sauter-mean diameter of the ethanol spray decreased by 15%, on average, in the presence of the acoustic field because of enhanced evaporation, while the droplet arrival rate at the probe volume increased due to changes in the flame structure. Analysis of the measured size distributions indicated that under an oscillating flow there was a larger population of droplets in the diameter range of 3--20 {micro}m. Experiments conducted with the water spray indicated that the oscillations did affect droplet size distributions in the ethanol spray due to enhanced evaporation caused by the relocation of the flame front inside and around the spray cone.

  4. Experimental and computational study of methane counterflow diffusion flames perturbed by trace amounts of either jet fuel or a 6-component

    E-Print Network [OSTI]

    Gomez, Alessandro

    with anticipated chemical kinetic behavior, based on thermal decomposition of large alkanes to smaller and smallerExperimental and computational study of methane counterflow diffusion flames perturbed by trace June 2009 Keywords: Diffusion flame Counterflow Surrogate Jet fuel a b s t r a c t The chemical

  5. 45th AIAA Aerospace Science Meeting and Exhibit, 8-11 January 2007, Reno, Nevada Verified Computations of Laminar Premixed Flames

    E-Print Network [OSTI]

    Computations of Laminar Premixed Flames Ashraf N. Al-Khateeb , Joseph M. Powers , and Samuel Paolucci all detailed continuum physics in the re- action zone for one-dimensional steady laminar premixed/or unsteady laminar premixed flame simulations in the literature. I. Introduction It is well understood

  6. Turbulent Flame Speeds and NOx Kinetics of HHC Fuels with Contaminants and High Dilution Levels

    SciTech Connect (OSTI)

    Petersen, Eric; Krejci, Michael; Mathieu, Olivier; Vissotski, Andrew; Ravi, Sankar; Sikes, Travis; Levacque, Anthony; Aul, Christopher; Peterson, Eric

    2011-09-30

    This progress report documents the first year of the project, from October 1, 2010 through September 30, 2011. Laminar flame speeds and ignition delay times have been measured for hydrogen and various compositions of H2/CO (syngas) at elevated pressures and elevated temperatures. Two constant-volume cylindrical vessels were used to visualize the spherical growth of the flame through the use of a schlieren optical setup to measure the laminar flame speed of the mixture. Hydrogen experiments were performed at initial pressures up to 10 atm and initial temperatures up to 443 K. A syngas composition of 50/50 was chosen to demonstrate the effect of carbon monoxide on H2-O2 chemical kinetics at standard temperature and pressures up to 10 atm. All atmospheric mixtures were diluted with standard air, while all elevated-pressure experiments were diluted with a He:O2 of 7:1 to minimize hydrodynamic instabilities. The laminar flame speed measurements of hydrogen and syngas are compared to available literature data over a wide range of equivalence ratios where good agreement can be seen with several data sets. Additionally, an improved chemical kinetics model is shown for all conditions within the current study. The model and the data presented herein agree well, which demonstrates the continual, improved accuracy of the chemical kinetics model. A high-pressure shock tube was used to measure ignition delay times for several baseline compositions of syngas at three pressures across a wide range of temperatures. The compositions of syngas (H2/CO) presented in this study include 80/20, 50/50, 40/60, 20/80, and 10/90, all of which are compared to previously published ignition delay times from a hydrogen-oxygen mixture to demonstrate the effect of carbon monoxide addition. Generally, an increase in carbon monoxide increases the ignition delay time, but there does seem to be a pressure dependency. At low temperatures and pressures higher than about 12 atm, the ignition delay times appear to be indistinguishable with an increase in carbon monoxide. However, at high temperatures the composition of H2 and CO has a strong influence on ignition delay times. Model agreement is good across the range of the study, particularly at the elevated pressures. Also an increase in carbon monoxide causes the activation energy of the mixture to decrease.

  7. Fiber optic spectroscopic digital imaging sensor and method for flame properties monitoring

    DOE Patents [OSTI]

    Zelepouga, Serguei A. (Hoffman Estates, IL); Rue, David M. (Chicago, IL); Saveliev, Alexei V. (Chicago, IL)

    2011-03-15

    A system for real-time monitoring of flame properties in combustors and gasifiers which includes an imaging fiber optic bundle having a light receiving end and a light output end and a spectroscopic imaging system operably connected with the light output end of the imaging fiber optic bundle. Focusing of the light received by the light receiving end of the imaging fiber optic bundle by a wall disposed between the light receiving end of the fiber optic bundle and a light source, which wall forms a pinhole opening aligned with the light receiving end.

  8. OPPDIF: A Fortran program for computing opposed-flow diffusion flames

    SciTech Connect (OSTI)

    Lutz, A.E.; Kee, R.J.; Grcar, J.F.; Rupley, F.M.

    1997-05-01

    OPPDIF is a Fortran program that computes the diffusion flame between two opposing nozzles. A similarity transformation reduces the two-dimensional axisymmetric flow field to a one-dimensional problem. Assuming that the radial component of velocity is linear in radius, the dependent variables become functions of the axial direction only. OPPDIF solves for the temperature, species mass fractions, axial and radial velocity components, and radial pressure gradient, which is an eigenvalue in the problem. The TWOPNT software solves the two-point boundary value problem for the steady-state form of the discretized equations. The CHEMKIN package evaluates chemical reaction rates and thermodynamic and transport properties.

  9. Systems and methods for detecting a flame in a fuel nozzle of a gas turbine

    DOE Patents [OSTI]

    Kraemer, Gilbert Otto; Storey, James Michael; Lipinski, John; Mestroni, Julio Enrique; Williamson, David Lee; Marshall, Jason Randolph; Krull, Anthony

    2013-05-07

    A system may detect a flame about a fuel nozzle of a gas turbine. The gas turbine may have a compressor and a combustor. The system may include a first pressure sensor, a second pressure sensor, and a transducer. The first pressure sensor may detect a first pressure upstream of the fuel nozzle. The second pressure sensor may detect a second pressure downstream of the fuel nozzle. The transducer may be operable to detect a pressure difference between the first pressure sensor and the second pressure sensor.

  10. Redox shuttles having an aromatic ring fused to a 1,1,4,4-tetrasubstituted cyclohexane ring

    DOE Patents [OSTI]

    Weng, Wei; Zhang, Zhengcheng; Amine, Khalil

    2015-12-01

    An electrolyte includes an alkali metal salt; an aprotic solvent; and a redox shuttle additive including an aromatic compound having at least one aromatic ring fused with at least one non-aromatic ring, the aromatic ring having two or more oxygen or phosphorus-containing substituents.

  11. Electronic Tuning of Nickel-Based Bis(dicarbollide) Redox Shuttles in Dye-Sensitized Solar Cells,

    SciTech Connect (OSTI)

    Spokoyny, Alexander M.; Li, Tina C.; Farha, Omar K.; Machan, C. W.; She, Chunxing; Stern, C. L.; Marks, Tobin J.; Hupp, Joseph T.; Mirkin, Chad

    2010-01-01

    Rational design of a new series of boron-functionalized Ni{sup III}/Ni{sup IV}–bis(dicarbollide) clusters results in a family of robust and tunable redox shuttles. This offers a means to rationally control the redox properties in dye-sensitized solar cells (DSCs), leading to exceptionally high open-circuit voltages.

  12. Investigation of nitrogen dilution effects on the laminar burning velocity and flame stability of syngas fuel at atmospheric condition

    SciTech Connect (OSTI)

    Prathap, C.; Ray, Anjan; Ravi, M.R. [Department of Mechanical Engineering, Indian Institute of Technology, Delhi, New Delhi 110016 (India)

    2008-10-15

    The objective of this investigation was to study the effect of dilution with nitrogen on the laminar burning velocity and flame stability of syngas fuel (50% H{sub 2}-50% CO by volume)-air (21% O{sub 2}-79% N{sub 2} by volume) mixtures. The syngas fuel composition considered in this work comprised x% N{sub 2} by volume and (100-x)% an equimolar mixture of CO and H{sub 2}. The proportion x (i.e., %N{sub 2}) was varied from 0 to 60% while the H{sub 2}/CO ratio was always kept as unity. Spherically expanding flames were generated by centrally igniting homogeneous fuel-air gas mixtures in a 40-L cylindrical combustion chamber fitted with optical windows. Shadowgraphy technique with a high-speed imaging camera was used to record the propagating spherical flames. Unstretched burning velocity was calculated following the Karlovitz theory for weakly stretched flames. Also, Markstein length was calculated to investigate the flame stability conditions for the fuel-air mixtures under consideration. Experiments were conducted for syngas fuel with different nitrogen proportions (0-60%) at 0.1 MPa (absolute), 302{+-}3K, and equivalence ratios ranging from 0.6 to 3.5. All the measurements were compared with the numerical predictions obtained using RUN-1DL and PREMIX with a contemporary chemical kinetic scheme. Dilution with nitrogen in different proportions in syngas resulted in (a) decrease in laminar burning velocity due to reduction in heat release and increase in heat capacity of unburned gas mixture and hence the flame temperature, (b) shift in occurrence of peak laminar burning velocity from {phi}=2.0 for 0% N{sub 2} dilution to {phi}=1.4 for 60% N{sub 2} dilution, (c) augmentation of the coupled effect of flame stretch and preferential diffusion on laminar burning velocity, and (d) shift in the equivalence ratio for transition from stable to unstable flames from {phi}=0.6 for 0% N{sub 2} dilution to {phi}=1.0 for 60% N{sub 2} dilution. The present work also indicated that if the fuel mole fraction in the wide range of fuel-air mixtures investigated is less than 22%, then those fuel mixtures are in the unstable regime with regard to preferential diffusion. (author)

  13. Effect of the composition of the hot product stream in the quasi-steady extinction of strained premixed flames

    SciTech Connect (OSTI)

    Coriton, Bruno; Smooke, Mitchell D.; Gomez, Alessandro [Department of Mechanical Engineering, Yale Center for Combustion Studies, Yale University, New Haven, CT 06520-8286 (United States)

    2010-11-15

    The extinction of premixed CH{sub 4}/O{sub 2}/N{sub 2} flames counterflowing against a jet of combustion products in chemical equilibrium was investigated numerically using detailed chemistry and transport mechanisms. Such a problem is of relevance to combustion systems with non-homogeneous air/fuel mixtures or recirculation of the burnt gases. Contrary to similar studies that were focused on heat loss/gain, depending on the degree of non-adiabaticity of the system, the emphasis here was on the yet unexplored role of the composition of counterflowing burnt gases in the extinction of lean-to-stoichiometric premixed flames. For a given temperature of the counterflowing products of combustion, it was found that the decrease of heat release with increase in strain rate could be either monotonic or non-monotonic, depending on the equivalence ratio {phi}{sub b} of the flame feeding the hot combustion product stream. Two distinct extinction modes were observed: an abrupt one, when the hot counterflowing stream consists of either inert gas or equilibrium products of a stoichiometric premixed flame, and a smooth extinction, when there is an excess of oxidizing species in the combustion product stream. In the latter case four burning regimes can be distinguished as the strain rate is progressively increased while the heat release decreases smoothly: an adiabatic propagating flame regime, a non-adiabatic propagating flame regime, the so-called partially-extinguished flame regime, in which the location of the peak of heat release crosses the stagnation plane, and a frozen flow regime. The flame structure was analyzed in detail in the different burning regimes. Abrupt extinction was attributed to the quenching of the oxidation layer with the entire H-OH-O radical pool being comparably reduced. Under conditions of smooth extinction, the behavior is different and the concentration of the H radical decreases the most with increasing strain rate, whereas OH and O remain comparatively abundant in the oxidation layer. As the profile of the heat release rate thickens, the oxidation layer is quenched and the attack of the fuel relies more heavily on the OH radicals. (author)

  14. Comparison of nanosecond and picosecond excitation for interference-free two-photon laser-induced fluorescence detection of atomic hydrogen in flames

    SciTech Connect (OSTI)

    Kulatilaka, Waruna D.; Patterson, Brian D.; Frank, Jonathan H.; Settersten, Thomas B

    2008-09-10

    Two-photon laser-induced fluorescence (TP-LIF) line imaging of atomic hydrogen was investigated in a series of premixed CH4/O2/N2, H2/O2, and H2/O2/N2 flames using excitation with either picosecond or nanosecond pulsed lasers operating at 205 nm. Radial TP-LIF profiles were measured for a range of pulse fluences to determine the maximum interference-free signal levels and the corresponding picosecond and nanosecond laser fluences in each of 12 flames. For an interference-free measurement, the shape of the TP-LIF profile is independent of laser fluence. For larger fluences, distortions in the profile are attributed to photodissociation of H2O, CH3, and/or other combustion intermediates, and stimulated emission. In comparison with the nanosecond laser, excitation with the picosecond laser can effectively reduce the photolytic interference and produces approximately an order of magnitude larger interference-free signal in CH4/O2/N2 flames with equivalence ratios in the range of 0.5{<=}{phi}{<=}1.4, and in H{sub 2}/O{sub 2} flames with 0.3{<=}{phi}{<=}1.2. Although photolytic interference limits the nanosecond laser fluence in all flames, stimulated emission, occurring between the laser-excited level, H(n=3), and H(n=2), is the limiting factor for picosecond excitation in the flames with the highest H atom concentration. Nanosecond excitation is advantageous in the richest ({phi}=1.64) CH4/O2/N2 flame and in H2/O2/N2 flames. The optimal excitation pulse width for interference-free H atom detection depends on the relative concentrations of hydrogen atoms and photolytic precursors, the flame temperature, and the laser path length within the flame.

  15. Modeling of the formation of short-chain acids in propane flames

    E-Print Network [OSTI]

    Battin-Leclerc, Frédérique; Jaffrezo, J L; Legrand, M

    2009-01-01

    In order to better understand their potential formation in combustion systems, a detailed kinetic mechanism for the formation of short-chain monocarboxylic acids, formic (HCOOH), acetic (CH3COOH), propionic (C2H5COOH) and propenic (C2H3COOH)) acids, has been developed. Simulations of lean (equivalence ratios from 0.9 to 0.48) laminar premixed flames of propane stabilized at atmospheric pressure with nitrogen as diluent have been performed. It was found that amounts up to 25 ppm of acetic acid, 15 ppm of formic acid and 1 ppm of C3 acid can be formed for some positions in the flames. Simulations showed that the more abundant C3 acid formed is propenic acid. A quite acceptable agreement has been obtained with the scarce results from the literature concerning oxygenated compounds, including aldehydes (CH2O, CH3CHO) and acids. A reaction pathways analysis demonstrated that each acid is mainly derived from the aldehyde of similar structure.

  16. Thermonuclear Flame Spreading on Rapidly Spinning Neutron Stars: Indications of the Coriolis Force?

    E-Print Network [OSTI]

    Sudip Bhattacharyya; Tod E. Strohmayer

    2007-08-27

    Millisecond period brightness oscillations during the intensity rise of thermonuclear X-ray bursts are likely caused by an azimuthally asymmetric, expanding burning region on the stellar surface. The time evolution of the oscillation amplitude during the intensity rise encodes information on how the thermonuclear flames spread across the stellar surface. This process depends on properties of the accreted burning layer, surface fluid motions, and the surface magnetic field structure, and thus can provide insight into these stellar properties. We present two examples of bursts from different sources that show a decrease in oscillation amplitude during the intensity rise. Using theoretical modeling, we demonstrate that the observed amplitude evolution of these bursts is not well described by a uniformly expanding circular burning region. We further show that by including in our model the salient aspects of the Coriolis force (as described by Spitkovsky, Levin, and Ushomirsky) we can qualitatively reproduce the observed evolution curves. Our modeling shows that the evolutionary structure of burst oscillation amplitude is sensitive to the nature of flame spreading, while the actual amplitude values can be very useful to constrain some source parameters.

  17. High-temperature aerosol formation in wood pellets flames: Spatially resolved measurements

    SciTech Connect (OSTI)

    Wiinikka, Henrik; Gebart, Rikard [Energy Technology Centre, Box 726, S-941 28 Piteaa (Sweden); Boman, Christoffer; Bostroem, Dan; Nordin, Anders; OEhman, Marcus [Energy Technology and Thermal Process Chemistry, Umeaa University, S-901 87 Umeaa (Sweden)

    2006-12-15

    The formation and evolution of high-temperature aerosols during fixed bed combustion of wood pellets in a realistic combustion environment were investigated through spatially resolved experiments. The purpose of this work was to investigate the various stages of aerosol formation from the hot flame zone to the flue gas channel. The investigation is important both for elucidation of the formation mechanisms and as a basis for development and validation of particle formation models that can be used for design optimization. Experiments were conducted in an 8-kW-updraft fired-wood-pellets combustor. Particle samples were withdrawn from the centerline of the combustor through 10 sampling ports by a rapid dilution sampling probe. The corresponding temperatures at the sampling positions were in the range 200-1450{sup o}C. The particle sample was size-segregated in a low-pressure impactor, allowing physical and chemical resolution of the fine particles. The chemical composition of the particles was investigated by SEM/EDS and XRD analysis. Furthermore, the experimental results were compared to theoretical models for aerosol formation processes. The experimental data show that the particle size distribution has two peaks, both of which are below an aerodynamic diameter of 2.5 {mu}m (PM{sub 2.5}). The mode diameters of the fine and coarse modes in the PM{sub 2.5} region were {approx}0.1 and {approx}0.8 {mu}m, respectively. The shape of the particle size distribution function continuously changes with position in the reactor due to several mechanisms. Early, in the flame zone, both the fine mode and the coarse mode in the PM{sub 2.5} region were dominated by particles from incomplete combustion, indicated by a significant amount of carbon in the particles. The particle concentrations of both the fine and the coarse mode decrease rapidly in the hot oxygen-rich flame due to oxidation of the carbon-rich particles. After the hot flame, the fine mode concentration and particle diameter increase gradually when the temperature of the flue gas drops. The main contribution to this comes from condensation on preexisting particles in the gas of alkali sulfates, alkali chlorides, and Zn species formed from constituents vaporized in the fuel bed. The alkali sulfates were found to condense at a temperature of {approx}950{sup o} and alkali chlorides condensed later at {approx}600{sup o}. This agrees well with results of chemical equilibrium calculation of the gas-to-particle conversion temperature. After the hot flame the coarse mode concentration decreased very little when the flue gas was cooled. In addition to carbon, the coarse mode consists of refractory metals and also considerable amounts of alkali. (author)

  18. Alpha Magnetic Spectrometer (AMS02) experiment on the International Space Station (ISS)

    E-Print Network [OSTI]

    Behcet Alpat

    2003-08-27

    The Alpha Magnetic Spectrometer experiment is realized in two phases. A precursor flight (STS-91) with a reduced experimental configuration (AMS01) has successfully flown on space shuttle Discovery in June 1998. The final version (AMS02) will be installed on the International Space Station (ISS) as an independent module in early 2006 for an operational period of three years. The main scientific objectives of AMS02 include the searches for the antimatter and dark matter in cosmic rays. In this work we will discuss the experimental details as well as the improved physics capabilities of AMS02 on ISS.

  19. Flame Enhancement and Quenching in Fluid Flows Natalia Vladimirovay,yPeter Constantinz, Alexander Kiselev*, Oleg Ruchays*

    E-Print Network [OSTI]

    Kiselev, Alex

    Flame Enhancement and Quenching in Fluid Flows Natalia Vladimirovay scale of the flow and laminar front thickness. For cellular flow, we o* *btain v ~ U1=4. We also study(T).* * (1) altered by the fluid flow. Specifically, moderately intense@t o levels of turbulence

  20. Nonpremixed ignition, laminar flame propagation, and mechanism reduction of n-butanol, iso-butanol, and methyl butanoate

    SciTech Connect (OSTI)

    Lu, Wei; Kelley, A. P.; Law, C. K.

    2011-01-01

    The non-premixed ignition temperature of n-butanol (CH{sub 3}CH{sub 2}CH{sub 2}CH{sub 2}OH), iso-butanol ((CH{sub 3}){sub 2}CHCH{sub 2}OH) and methyl butanoate (CH{sub 3}CH{sub 2}CH{sub 2}COOCH{sub 3}) was measured in a liquid pool assembly by heated oxidizer in a stagnation flow for system pressures of 1 and 3 atm. In addition, the stretch-corrected laminar flame speeds of mixtures of air–n-butanol/iso-butanol/methyl butanoate were determined from the outwardly propagating spherical flame at initial pressures of up to 2 atm, for an extensive range of equivalence ratio. The ignition temperature and laminar flame speeds of n-butanol and methyl butanoate were computationally simulated with three recently developed kinetic mechanisms in the literature. Dominant reaction pathways to ignition and flame propagation were identified and discussed through a chemical explosive mode analysis (CEMA) and sensitivity analysis. The detailed models were further reduced through a series of systematic strategies. The reduced mechanisms provided excellent agreement in both homogeneous and diffusive combustion environments and greatly improved the computation efficiency.

  1. November 1, 1994 / Vol. 19, No. 21 / OPTICS LETTERS 1681 Laser-induced thermal grating effects in flames

    E-Print Network [OSTI]

    in flames Skip Williams,* Larry A. Rahn, Phillip H. Paul, and Jon W. Forsmant Combustion Research Facility and E2 are supplied from a cw ring-dye laser that was pulse amplified by a single-mode Nd:YAG- pumped having pulse widths of -20 ns and bandwidths of -0.001 cm-1. The scattering field, E3, was derived from

  2. Temperature Measurement with a Conditional Two-line OH-PLIF Technique in an Actively Controlled Coaxial Jet Flame

    E-Print Network [OSTI]

    Tokyo, University of

    , and this results in the increased CO emission. Key Words : Flame, Jet, Laser, Combustion Control, Laser /cm-1 /pulse 2 5 PLIF (14) 2.4 104 Pa 283 nm ~20 mJ/cm2 / pulse 2 6 2 (14) 10 mm (Shimadzu, CFP-8000

  3. IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 37, NO. 12, DECEMBER 2009 2303 Nitric Oxide Formation in a Premixed Flame With

    E-Print Network [OSTI]

    Lee, Tonghun

    IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 37, NO. 12, DECEMBER 2009 2303 Nitric Oxide Formation in a Premixed Flame With High-Level Plasma Energy Coupling Xing Rao, Igor B. Matveev, and Tonghun Lee Abstract) in a transient-arc direct-current plasmatron igniter using premixed air/fuel mixtures. Quantitative measurements

  4. The Influence of Spatial Discreteness on the Thermo-Diffusive Instability of Flame Propagation with Infinite Lewis Number

    E-Print Network [OSTI]

    Mi, XiaoCheng; Goroshin, Samuel; Bergthorson, Jeffrey M

    2015-01-01

    The dynamics of flame propagation in systems with infinite Lewis number and spatially discretized sources of heat release is examined, which is applicable to the combustion of suspensions of fuel particles in air. The system is analyzed numerically using a one-dimensional heat equation with a source term for the reaction progress variable, which is specified to have zero diffusivity, and the model reveals a spectrum of flame-propagation regimes. For the case of a switch-type reaction rate and homogeneous media (continuous regime), the flame propagates steadily at a velocity in agreement with analytical solutions. As the sources are spatially concentrated into {\\delta}-function-like sources, propagation approaches the discrete regime with a fixed period between ignition of the sources, for which an analytic solution is also available for validation. When the source term is governed by an Arrhenius rate and the activation energy is increased beyond the stability boundary, the flame begins to exhibit a long-wave...

  5. An analytical investigation of primary zone combustion temperatures and NOx production for turbulent jet flames using low-BTU fuels 

    E-Print Network [OSTI]

    Carney, Christopher Mark

    1995-01-01

    The objective of this research project was to identify and determine the effect of jet burner operating variables that influence combustion of low-BTU gases. This was done by simulating the combustion of a low-BTU fuel in a jet flame and predicting...

  6. The Influence of Spatial Discreteness on the Thermo-Diffusive Instability of Flame Propagation with Infinite Lewis Number

    E-Print Network [OSTI]

    XiaoCheng Mi; Andrew J. Higgins; Samuel Goroshin; Jeffrey M. Bergthorson

    2015-12-04

    The dynamics of flame propagation in systems with infinite Lewis number and spatially discretized sources of heat release is examined, which is applicable to the combustion of suspensions of fuel particles in air. The system is analyzed numerically using a one-dimensional heat equation with a source term for the reaction progress variable, which is specified to have zero diffusivity, and the model reveals a spectrum of flame-propagation regimes. For the case of a switch-type reaction rate and homogeneous media (continuous regime), the flame propagates steadily at a velocity in agreement with analytical solutions. As the sources are spatially concentrated into {\\delta}-function-like sources, propagation approaches the discrete regime with a fixed period between ignition of the sources, for which an analytic solution is also available for validation. When the source term is governed by an Arrhenius rate and the activation energy is increased beyond the stability boundary, the flame begins to exhibit a long-wavelength (4-5 times the thermal flame thickness) oscillation characteristic of the thermo-diffusive instability, in good agreement with prior stability analysis. When spatial discreteness is introduced, a competition is observed between the long-period oscillations of the thermo-diffusive instability and the pulsations associated with the rapid heat release of the concentrated sources. Interestingly, the presence of spatial discreteness is able to excite higher modes (period doubling and chaotic solutions) of the thermo-diffusive instability, suggesting that the introduction of discreteness may have an influence qualitatively similar to that of increasing activation energy. Relevance of the model parameters to experimental systems is then discussed.

  7. Multi-vehicle Mobility Allowance Shuttle Transit (MAST) System - An Analytical Model to Select the Fleet Size and a Scheduling Heuristic 

    E-Print Network [OSTI]

    Lu, Wei

    2012-10-19

    The mobility allowance shuttle transit (MAST) system is a hybrid transit system in which vehicles are allowed to deviate from a fixed route to serve flexible demand. A mixed integer programming (MIP) formulation for the static scheduling problem...

  8. Ni(III)/(IV) Bis(dicarbollide) as a Fast, Noncorrosive Redox Shuttle for Dye-Sensitized Solar Cells

    SciTech Connect (OSTI)

    Li, Tina C.; Spokoyny, Alexander M.; She, Chunxing; Farha, Omar K.; Mirkin, Chad; Marks, Tobin J.; Hupp, Joseph T.

    2010-01-01

    Nickel bis(dicarbollide) is used as a fast, one-electron outer sphere redox couple in dye-sensitized solar cells. Device performances with this anionic shuttle are investigated with different electrolyte concentrations and additives, using only 0.030 M of the Ni(III) bis(dicarbollide) to efficiently regenerate the ruthenium dye. Atomic layer deposition of Al{sub 2}O{sub 3} on the nanoparticulate TiO{sub 2} photoanodes is further used to improve device performances, increasing current densities almost 2-fold and attaining power conversion efficiencies 10× greater than its metallocene analogue, ferrocene/ferrocenium. Open-circuit voltage decay is used to probe the kinetics of the Ni(III)/(IV) bis(dicarbollide) redox couple, and electron interception is found to be 10{sup 3}× slower than ferrocene/ferrocenium, explaining the large discrepancy in open-circuit voltage potentials between these two redox shuttles.

  9. Ni(III)/(IV) Bis(dicarbollide) as a Fast, Noncorrosive Redox Shuttle for Dye-Sensitized Solar Cells

    SciTech Connect (OSTI)

    Li, Tina C. [Northwestern Univ., Evanston, IL (United States); Spokoyny, Alexander M. [Northwestern Univ., Evanston, IL (United States); Chunxing, She [Northwestern Univ., Evanston, IL (United States); Farha, Omar K. [Northwestern Univ., Evanston, IL (United States); Mirkin, Chad A. [Northwestern Univ., Evanston, IL (United States); Marks, Tobin J. [Northwestern Univ., Evanston, IL (United States); Hupp, Joseph T. [Northwestern Univ., Evanston, IL (United States)

    2010-01-01

    Nickel bis(dicarbollide) is used as a fast, one-electron outer sphere redox couple in dye-sensitized solar cells. Device performances with this anionic shuttle are investigated with different electrolyte concentrations and additives, using only 0.030 M of the Ni(III) bis(dicarbollide) to efficiently regenerate the ruthenium dye. Atomic layer deposition of Al{sub 2}O{sub 3} on the nanoparticulate TiO{sub 2} photoanodes is further used to improve device performances, increasing current densities almost 2-fold and attaining power conversion efficiencies ?10× greater than its metallocene analogue, ferrocene/ferrocenium. Open-circuit voltage decay is used to probe the kinetics of the Ni(III)/(IV) bis(dicarbollide) redox couple, and electron interception is found to be ?10{sup 3}× slower than ferrocene/ferrocenium, explaining the large discrepancy in open-circuit voltage potentials between these two redox shuttles.

  10. The BRO proteins of Bombyx mori nucleopolyhedrovirus are nucleocytoplasmic shuttling proteins that utilize the CRM1-mediated nuclear export pathway

    SciTech Connect (OSTI)

    Kang, Won Kyung [Molecular Entomology Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198 (Japan)]. E-mail: wkkang@riken.jp; Kurihara, Masaaki [Molecular Entomology Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198 (Japan)]. E-mail: mkuri@riken.jp; Matsumoto, Shogo [Molecular Entomology Laboratory, RIKEN, 2-1 Hirosawa, Wako 351-0198 (Japan)]. E-mail: smatsu@riken.jp

    2006-06-20

    The BRO proteins of Bombyx mori nucleopolyhedrovirus (BmNPV) display a biphasic pattern of intracellular localization during infection. At early times, they reside in the nucleus but then show both cytoplasmic and nuclear localization as the infection proceeds. Therefore, we examined the possibility of nuclear export. Using inhibitors, we reveal that BmNPV BRO proteins shuttle between the nucleus and cytoplasm. Mutations on the leucine-rich region of BRO proteins resulted in nuclear accumulation of transiently expressed proteins, suggesting that this region functions as a CRM1-dependent nuclear export signal (NES). On the contrary, mutant BRO-D with an altered NES did not show nuclear accumulation in infected cells, although protein production seemed to be reduced. RT-PCR analysis showed that the lower level of protein production was due to a reduction in RNA synthesis. Taken together, our results suggest that BRO proteins are nucleocytoplasmic shuttling proteins that utilize the CRM1-mediated nuclear export pathway.

  11. Unravelling the chemical inhomogeneity of PNe with VLT FLAMES integral-field unit spectroscopy

    E-Print Network [OSTI]

    Y. G. Tsamis; J. R. Walsh; D. Pequignot; M. J. Barlow; X. -W. Liu; I. J. Danziger

    2006-05-07

    Recent weak emission-line long-slit surveys and modelling studies of PNe have convincingly argued in favour of the existence of an unknown component in the planetary nebula plasma consisting of cold, hydrogen-deficient gas, as an explanation for the long-standing recombination-line versus forbidden-line temperature and abundance discrepancy problems. Here we describe the rationale and initial results from a detailed spectroscopic study of three Galactic PNe undertaken with the VLT FLAMES integral-field unit spectrograph, which advances our knowledge about the small-scale physical properties, chemical abundances and velocity structure of these objects across a two-dimensional field of view, and opens up for exploration an uncharted territory in the study and modelling of PNe and photoionized nebulae in general.

  12. Non-normality in combustion-acoustic interaction in diffusion flames: a critical revision

    E-Print Network [OSTI]

    Magri, Luca; Sujith, R I; Juniper, Matthew P

    2013-01-01

    Perturbations in a non-normal system can grow transiently even if the system is linearly stable. If this transient growth is sufficiently large, it can trigger self-sustained oscillations from small initial disturbances. This has important practical consequences for combustion-acoustic oscillations, which are a continual problem in rocket and aircraft engines. Balasubramanian and Sujith (Journal of Fluid Mechanics, 2008, 594, 29-57) modelled an infinite-rate chemistry diffusion flame in an acoustic duct and found that the transient growth in this system can amplify the initial energy by a factor, $G_{max}$, of order $10^5$ to $10^7$. However, recent investigations by L. Magri & M. P. Juniper have brought to light certain errors in that paper. When the errors are corrected, $G_{max}$ is found to be of order 1 to 10, revealing that non-normality is not as influential as it was thought to be.

  13. Synchrotron photoionization mass spectrometry study of intermediates in fuel-rich 1,2-dimethoxyethane flame

    SciTech Connect (OSTI)

    Lin, Z. K.; Han, D. L.; Li, S. F.; Li, Y. Y.; Yuan, T.

    2009-04-21

    Intermediates in a fuel-rich premixed laminar 1,2-dimethoxyethane (DME) flame are studied by molecular beam mass spectrometry combined with tunable synchrotron vacuum ultraviolet photoionization. About 30 intermediate species are identified in the present work, and their mole fraction profiles are evaluated. The experimental results show that the formations of intermediates, both hydrocarbons and oxygenated hydrocarbons, are closely linked to the structure of fuel, which is consistent with the previous reports. Species produced from H atom abstraction and beta scission of DME usually have much higher concentrations than others. The oxygen atoms in DME are considered to act as partitions of the primary intermediates; therefore farther reactions among these primary intermediates are difficult to occur, resulting in absence of most large intermediate species.

  14. Electronic Tuning of Nickel-Based Bis(dicarbollide) Redox Shuttles in Dye-Sensitized Solar Cells

    SciTech Connect (OSTI)

    Spokoyny, Alexander M. [Northwestern Univ., Evanston, IL (United States); Li, Tina C. [Northwestern Univ., Evanston, IL (United States); Farha, Omar K. [Northwestern Univ., Evanston, IL (United States); Machan, Charles W. [Northwestern Univ., Evanston, IL (United States); She, Chunxing [Northwestern Univ., Evanston, IL (United States); Stern, Charlotte L. [Northwestern Univ., Evanston, IL (United States); Marks, Tobin J. [Northwestern Univ., Evanston, IL (United States); Hupp, Joseph T. [Northwestern Univ., Evanston, IL (United States); Mirkin, Chad A. [Northwestern Univ., Evanston, IL (United States)

    2010-01-01

    Rational design of a new series of boron-functionalized Ni{sup III}/Ni{sup IV}–bis(dicarbollide) clusters results in a family of robust and tunable redox shuttles (see diagram; EDG and EWG denote electron-donating and -withdrawing groups, respectively). This offers a means to rationally control the redox properties in dye-sensitized solar cells (DSCs), leading to exceptionally high open-circuit voltages.

  15. Self-propelled in-tube shuttle and control system for automated measurements of magnetic field alignment

    SciTech Connect (OSTI)

    Boroski, W.N.; Nicol, T.H. ); Pidcoe, S.V. . Space Systems Div.); Zink, R.A. )

    1990-03-01

    A magnetic field alignment gauge is used to measure the field angle as a function of axial position in each of the magnets for the Superconducting Super Collider (SSC). Present measurements are made by manually pushing the through the magnet bore tube and stopping at intervals to record field measurements. Gauge location is controlled through graduation marks and alignment pins on the push rods. Field measurements are recorded on a logging multimeter with tape output. Described is a computerized control system being developed to replace the manual procedure for field alignment measurements. The automated system employs a pneumatic walking device to move the measurement gauge through the bore tube. Movement of the device, called the Self-Propelled In-Tube Shuttle (SPITS), is accomplished through an integral, gas driven, double-acting cylinder. The motion of the SPITS is transferred to the bore tube by means of a pair of controlled, retractable support feet. Control of the SPITS is accomplished through an RS-422 interface from an IBM-compatible computer to a series of solenoid-actuated air valves. Direction of SPITS travel is determined by the air-valve sequence, and is managed through the control software. Precise axial position of the gauge within the magnet is returned to the control system through an optically-encoded digital position transducer attached to the shuttle. Discussed is the performance of the transport device and control system during preliminary testing of the first prototype shuttle. 1 ref., 7 figs.

  16. SPACE DAILY SPACE WAR TERRA DAILY MARS DAILY SPACE MART SPACE TRAVEL World's Smallest Universal Material

    E-Print Network [OSTI]

    Espinosa, Horacio D.

    SPACE DAILY SPACE WAR TERRA DAILY MARS DAILY SPACE MART SPACE TRAVEL NANO TECH World's Smallest, professor of mechanical Get Our Free Newsletters Via Email Space - War - Earth - Energy - China your email yes Search All Of Our Sites In One Search SpaceDaily - SpaceWar - TerraDaily Search Horacio D

  17. Gravity, radiation, and coflow effects on partially premixed flames Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544

    E-Print Network [OSTI]

    Aggarwal, Suresh K.

    with the ambient air.3 Partially premixed flames occur in many applications including gas-fired domestic burners, industrial furnaces, and Bunsen burners. Partial premixing also occurs under other circumstances

  18. Modeling CO[subscript 2] Chemical Effects on CO Formation in Oxy-Fuel Diffusion Flames Using Detailed, Quasi-Global, and Global Reaction Mechanisms

    E-Print Network [OSTI]

    Chen, Lei

    Interest in oxy-fuel combustion as one of the leading carbon capture technologies has grown significantly in the past two decades. Experimental studies have shown higher CO concentration in oxy-fuel diffusion flames than ...

  19. Flame-synthesis limits and self-catalytic behavior of carbon nanotubes using a double-faced wall stagnation flow burner

    SciTech Connect (OSTI)

    Woo, S.K.; Hong, Y.T.; Kwon, O.C.

    2009-10-15

    Flame-synthesis limits of carbon nanotubes (CNTs) are measured using a double-faced wall stagnation flow (DWSF) burner that shows potential in mass production of CNTs. With nitrogen-diluted premixed ethylene-air flames established on the nickel-coated stainless steel double-faced plate wall, the limits of CNT formation are determined using field-emission scanning and transmission electron microscopies and Raman spectroscopy. Also, self-catalytic behavior of the synthesized CNTs is evaluated using the DWSF burner with a CNT-deposited stainless steel double-faced plate wall. Results show narrow fuel-equivalence ratio limits of multi-walled CNT (MWCNT)-synthesis at high flame stretch rates and substantially extended limits at low flame stretch rates. This implies that the synthesis limits are very sensitive to the fuel-equivalence ratio variation for the high stretch rate conditions, yielding a lot of impurities and soot rather than MWCNTs. The enhanced ratio of tube inner diameter to wall thickness of the MWCNTs synthesized using a CNT self-catalytic flame-synthesis process is observed, indicating that the quality of metal-catalytic, flame-synthesized MWCNTs can be much improved via the process. Thus, using a DWSF burner with the CNT self-catalytic process has potential in mass production of MWCNTs with improved quality. (author)

  20. Lyapunov functions nonlinear spaces

    E-Print Network [OSTI]

    Hafstein, Sigurður Freyr

    Lyapunov functions on nonlinear spaces R. Sepulchre -- University of Liege, Belgium Reykjavik - July 2013 Constructing Lyapunov functions: a personal journey · Lyap functions in linear spaces (1994: homogeneous spaces with flat, positive, and negative curvature) Lyapunov functions in linear spaces 3

  1. Experimental study of the structure of rich premixed 1,3-butadiene/CH4/O2/Ar flame

    E-Print Network [OSTI]

    Gueniche, Hadj-Ali; Fournet, René; Battin-Leclerc, Frédérique

    2006-01-01

    The structure of a laminar rich premixed 1,3-C4H6/CH4/O2/Ar flame have been investigated. 1,3-Butadiene, methane, oxygen and argon mole fractions are 0.033; 0.2073; 0.3315, and 0.4280, respectively, for an equivalent ratio of 1.80. The flame has been stabilized on a burner at a pressure of 6.7 kPa (50 Torr). The concentration profiles of stable species were measured by gas chromatography after sampling with a quartz probe. Quantified species included carbon monoxide and dioxide, methane, oxygen, hydrogen, ethane, ethylene, acetylene, propyne, allene, propene, cyclopropane, 1,3-butadiene, butenes, 1-butyne, vinylacetylene, diacetylene, C5 compounds, benzene, and toluene. The temperature was measured thanks to a thermocouple in PtRh (6%)-PtRh (30%) settled inside the enclosure and ranged from 900 K close to the burner up to 2100 K.

  2. Social Media: Space Weather #SpaceWeather

    E-Print Network [OSTI]

    ://www.swpc.noaa.gov/impacts/spaceweatherandgpssystems #SpaceWeather #12;Space Weather Impacts on the Power Grid Facebook The electric power grid. To learn about space weather and impacts to the electric grid visit http on the Power Grid Space Weather and the Aurora Borealis What are Solar Flares? What are Coronal Mass

  3. TIME-VARYING FLAME IONIZATION SENSING APPLIED TO NATURAL GAS AND PROPANE BLENDS IN A PRESSURIZED LEAN PREMIXED (LPM) COMBUSTOR

    SciTech Connect (OSTI)

    D. L. Straub; B. T. Chorpening; E. D. Huckaby; J. D. Thornton; W. L. Fincham

    2008-06-13

    In-situ monitoring of combustion phenomena is a critical need for optimal operation and control of advanced gas turbine combustion systems. The concept described in this paper is based on naturally occurring flame ionization processes that accompany the combustion of hydrocarbon fuels. Previous work has shown that flame ionization techniques may be applied to detect flashback, lean blowout, and some aspects of thermo-acoustic combustion instabilities. Previous work has focused on application of DC electric fields. By application of time-varying electric fields, significant improvements to sensor capabilities have been observed. These data have been collected in a lean premixed combustion test rig operating at 0.51-0.76 MPa (5-7.5 atm) with air preheated to 588 K (600°F). Five percent of the total fuel flow is injected through the centerbody tip as a diffusion pilot. The fuel composition is varied independently by blending approximately 5% (volume) propane with the pipeline natural gas. The reference velocity through the premixing annulus is kept constant for all conditions at a nominal value of 70 m/s. The fuel-air equivalence ratio is varied independently from 0.46 – 0.58. Relative to the DC field version, the time-varying combustion control and diagnostic sensor (TV-CCADS) shows a significant improvement in the correlation between the measured flame ionization current and local fuel-air equivalence ratio. In testing with different fuel compositions, the triangle wave data show the most distinct change in flame ionization current in response to an increase in propane content. Continued development of this sensor technology will improve the capability to control advanced gas turbine combustion systems, and help address issues associated with variations in fuel supplies.

  4. Gas-flow measurements in a jet flame using cross-correlation of high speed particle-images

    SciTech Connect (OSTI)

    Shioji, Masahiro; Kawasaki, Kiyoshi; Kawanabe, Hiroshi; Ikegami, Makoto

    1999-07-01

    Time changes of a two-dimensional distribution of velocities in a methane jet flame and a nitrogen jet are measured by cross-correlation particle image velocimetry (PIV). The mean velocity and the intensity of turbulence are obtained and compared with those measured by HWA in order to ascertain the accuracy of PIV. Furthermore, the effect of combustion on turbulence characteristics is discussed based on the deformation of eddies with time change and distribution of time and spatial scales.

  5. Rotational coherent anti-Stokes Raman spectroscopy (CARS) applied to thermometry in high-pressure hydrocarbon flames

    SciTech Connect (OSTI)

    Vestin, Fredrik; Sedarsky, David; Collin, Robert; Alden, Marcus; Linne, Mark; Bengtsson, Per-Erik

    2008-07-15

    Dual-broadband rotational coherent anti-Stokes Raman spectroscopy (DB-RCARS) has been investigated for thermometry under high-pressure and high-temperature conditions, in the product gas of fuel-lean hydrocarbon flames up to 1 MPa. Initial calibration measurements made in nitrogen, oxygen, and air, at pressures up to 1.55 MPa and temperatures up to 1800 K, showed good agreement between experimental and theoretical spectra. In the high-pressure flames, high-quality single-shot spectra were recorded in which nitrogen lines dominated, and peaks from CO{sub 2} and O{sub 2} were also visible. A spectral model including the species N{sub 2}, CO{sub 2}, and O{sub 2}, as well as the best available Raman linewidth models for flame thermometry, were used to evaluate the experimental spectra. Experimental problems as well as considerations related to the spectral evaluation are discussed. This work demonstrates the significant potential of DB-RCARS thermometry for applications in high-pressure and high-temperature environments. (author)

  6. Development of flame retardant PV module encapsulants: Volume 1. Final report

    SciTech Connect (OSTI)

    Galica, J.P.

    1998-06-01

    This Phase 1 final report covers the work performed by Springborn Testing and Research, Inc., for the period October 1, 1997 to June 30, 1998 under the Department of Energy Cooperative Agreement Number DE-FC36-97GO10255, entitled Development of Flame Retardant PV Module Encapsulants. While use of roof-mounted arrays has always been an attractive means of deploying PV, only within recent years have such building integrated concepts (BIPV) found renewed interest among module makers and end-users. Prior to building integrated and rooftop applications, flammability requirements for modules have not been a great industry concern. However, with growing interest in BIPV and the requirement for building code requirements for commercial and industrial structures, flammability issues have become a barrier to entry for many module constructions into this potentially huge domestic market for PV. The overall goal of the 3 phase PV BONUS two project is to develop and commercialize a line of fire retardant encapsulation materials to serve the emerging building integrated and building mounted PV market. The objectives of the Phase 1 effort are limited to concept development and business planning activities.

  7. A numerical study of soot aggregate formation in a laminar coflow diffusion flame

    SciTech Connect (OSTI)

    Zhang, Q.; Thomson, M.J. [Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario, M5S 3G8 (Canada); Guo, H.; Liu, F.; Smallwood, G.J. [Institute for Chemical Process and Environmental Technology, National Research Council of Canada, Building M-9, 1200 Montreal Road, Ottawa, Ontario, K1A 0R6 (Canada)

    2009-03-15

    Soot aggregate formation in a two-dimensional laminar coflow ethylene/air diffusion flame is studied with a pyrene-based soot model, a detailed sectional aerosol dynamics model, and a detailed radiation model. The chemical kinetic mechanism describes polycyclic aromatic hydrocarbon formation up to pyrene, the dimerization of which is assumed to lead to soot nucleation. The growth and oxidation of soot particles are characterized by the HACA surface mechanism and pyrene-soot surface condensation. The mass range of the solid soot phase is divided into thirty-five discrete sections and two equations are solved in each section to model the formation of the fractal-like soot aggregates. The coagulation model is improved by implementing the aggregate coagulation efficiency. Several physical processes that may cause sub-unitary aggregate coagulation efficiency are discussed. Their effects on aggregate structure are numerically investigated. The average number of primary soot particles per soot aggregate n{sub p} is found to be a strong function of the aggregate coagulation efficiency. Compared to the available experimental data, n{sub p} is well reproduced with a constant 20% aggregate coagulation efficiency. The predicted axial velocity, OH mole fraction, and C{sub 2}H{sub 2} mole fraction are validated against experimental data in the literature. Reasonable agreements are obtained. Finally, a sensitivity study of the effects of particle coalescence on soot volume fraction and soot aggregate nanostructure is conducted using a coalescence cutoff diameter method. (author)

  8. Multi-ported, internally recuperated burners for direct flame impingement heating applications

    DOE Patents [OSTI]

    Abbasi, Hamid A. (Naperville, IL); Kurek, Harry (Dyer, IN); Chudnovsky, Yaroslav (Skokie, IL); Lisienko, Vladimir G. (Ekaterinburg, RU); Malikov, German K. (Ekaterinburg, RU)

    2010-08-03

    A direct flame impingement method and apparatus employing at least one multi-ported, internally recuperated burner. The burner includes an innermost coaxial conduit having a first fluid inlet end and a first fluid outlet end, an outermost coaxial conduit disposed around the innermost coaxial conduit and having a combustion products outlet end proximate the first fluid inlet end of the innermost coaxial conduit and a combustion products inlet end proximate the first fluid outlet end of the innermost coaxial conduit, and a coaxial intermediate conduit disposed between the innermost coaxial conduit and the outermost coaxial conduit, whereby a second fluid annular region is formed between the innermost coaxial conduit and the intermediate coaxial conduit and a combustion products annular region is formed between the intermediate coaxial conduit and the outermost coaxial conduit. The intermediate coaxial conduit has a second fluid inlet end proximate the first fluid inlet end of the innermost coaxial conduit and a second fluid outlet end proximate the combustion products inlet end of the outermost coaxial conduit.

  9. X-ray Burst Oscillations: From Flame Spreading to the Cooling Wake

    E-Print Network [OSTI]

    Simin Mahmoodifar; Tod Strohmayer

    2015-10-16

    Type I X-ray bursts are thermonuclear flashes observed from the surface of accreting neutron stars in Low Mass X-ray Binaries. Oscillations have been observed during the rise and/or decay of some of these X-ray bursts. Those seen during the rise can be well explained by a spreading hot spot model, but to date there haven't been any quantitative studies that consistently track the oscillation amplitude both during the rise and decay (tail) of bursts. Here we compute the light curves and amplitudes of oscillations in X-ray burst models that realistically account for both flame spreading and subsequent cooling. We present results for two such "cooling wake" models, a "canonical" cooling model where each patch on the neutron star surface heats and cools identically, and an "asymmetric" model where parts of the star cool at different rates. We show that while canonical cooling models can generate oscillations in the tails of bursts, they cannot easily produce the highest observed modulation amplitudes. Alternatively, a simple model with asymmetric cooling can achieve higher amplitudes consistent with the observations.

  10. Numerical analysis of the effect of acetylene and benzene addition to low-pressure benzene-rich flat flames on polycyclic aromatic hydrocarbon formation

    SciTech Connect (OSTI)

    Kunioshi, Nilson; Komori, Seisaku; Fukutani, Seishiro

    2006-10-15

    A modification of the CHEMKIN II package has been proposed for modeling addition of an arbitrary species at an arbitrary temperature to an arbitrary distance from the burner along a flat flame. The modified program was applied to the problem of addition of acetylene or benzene to different positions of a 40-Torr, {phi}=2.4 benzene/O{sub 2}/40%-N{sub 2} premixed flame to reach final equivalence ratios of {phi}=2.5 and 2.681. The results obtained showed that acetylene addition to early positions of the flame led to significant increase in pyrene production rates, but pyrene concentrations were lower in the flames with acetylene addition in both the {phi}=2.5 and 2.681 cases. Addition of benzene to the flame did not alter pyrene production rates in either the {phi}=2.5 or 2.681 cases; however, for {phi}=2.5, pyrene concentrations increased with benzene addition, while for {phi}=2.681, pyrene contents decreased in comparison to the correspondent flames with no addition. Acetylene addition led to a significant increase in pyrene production rates, but the pyrene levels dropped due to increase in the flow velocity. Pyrene production rates were not sensitive to benzene addition, but pyrene contents increased with benzene addition when the flow velocity decreased. These results show that PAH concentration changes accompanying species addition to flames should be interpreted carefully, because an increase or decrease in the content of a PAH species does not necessarily reflect an effect on its formation rate or mechanism. (author)

  11. Normal, Not Paracompact Spaces

    E-Print Network [OSTI]

    Fleissner, William G.

    1982-07-01

    We describe some recently constructed counterexamples in general topology, including a normal, nonmetrizable Moore space, a normal para-Lindelof, not paracompact space, and a normal, screenable, not paracompact space....

  12. Space Solar Power Program

    SciTech Connect (OSTI)

    Arif, H.; Barbosa, H.; Bardet, C.; Baroud, M.; Behar, A.; Berrier, K.; Berthe, P.; Bertrand, R.; Bibyk, I.; Bisson, J.; Bloch, L.; Bobadilla, G.; Bourque, D.; Bush, L.; Carandang, R.; Chiku, T.; Crosby, N.; De Seixas, M.; De Vries, J.; Doll, S.; Dufour, F.; Eckart, P.; Fahey, M.; Fenot, F.; Foeckersperger, S.; Fontaine, J.E.; Fowler, R.; Frey, H.; Fujio, H.; Gasa, J.M.; Gleave, J.; Godoe, J.; Green, I.; Haeberli, R.; Hanada, T.; Ha

    1992-08-01

    Information pertaining to the Space Solar Power Program is presented on energy analysis; markets; overall development plan; organizational plan; environmental and safety issues; power systems; space transportation; space manufacturing, construction, operations; design examples; and finance.

  13. Sculpting space through sound

    E-Print Network [OSTI]

    Nakagawa, Junko, 1975-

    2002-01-01

    How does one experience space? What kind of information do humans collect in the process of constructing space in their mind? How does one begin to understand volume, light, texture, material, smell and sense of space? The ...

  14. Turbulent flame speeds and NOx kinetics of HHC fuels with contaminants and high dilution levels

    SciTech Connect (OSTI)

    Petersen, Eric; Krejci, Michael; Mathieu, Olivier; Vissotski, Andrew; Ravi, Sankar; Plichta, Drew; Sikes, Travis; Levacque, Anthony; Aul, Christopher; Petersen, Eric

    2012-09-30

    This progress report documents the second year of the project, from October 1, 2011 through September 30, 2012. Characterization of the new turbulent flame speed vessel design was completed. Turbulence statistics of three impellers with different geometric features were measured using particle image velocimetry inside a Plexiglas model (~1:1 scale) of a cylindrical flame speed vessel (30.5 cm ID × 35.6 cm L). With four impellers arranged in a central-symmetric configuration, turbulence intensities between 1.2 and 1.7 m/s with negligible mean flow (0.1u´) were attained at the lowest fan speeds. Acceptable ranges for homogeneity and isotropy ratios of the velocity fields were set within a narrow bandwidth near unity (0.9-1.1). Homogeneity ratios were unaffected by changes to the impeller geometry, and the prototype with the higher number of blades caused the flow to become anisotropic. The integral length scale of the flow fields varied between 27 and 20 mm, which correlates well with those typically observed inside a gas turbine combustor. The mechanism to independently vary the intensity level and the integral length scale was established, where turbulence intensity level was dependent on the rotational speed of the fan, and the integral length scale decreased with increasing blade pitch angle. Ignition delay times of H?/O? mixtures highly diluted with Ar and doped with various amounts of N?O (100, 400, 1600, 3200 ppm) were measured in a shock tube behind reflected shock waves over a wide range of temperatures (940-1675 K). The pressure range investigated during this work (around 1.6, 13, and 30 atm) allows studying the effect of N?O on hydrogen ignition at pressure conditions that have never been heretofore investigated. Ignition delay times were decreased when N?O was added to the mixture only for the higher nitrous oxide concentrations, and some changes in the activation energy were also observed at 1.5 and 30 atm. When it occurred, the decrease in the ignition delay time was proportional to the amount of N?O added and depended on pressure and temperature conditions. A detailed chemical kinetics model was developed using kinetic mechanisms from the literature. This model predicts well the experimental data obtained during this study and from the literature. The chemical analysis using this model showed that the decrease in the ignition delay time was mainly due to the reaction N?O +M ? N? + O +M which provides O atoms to strengthen the channel O + H? ? OH + H. Ignition delay times have been measured behind reflected shock waves at 1.5, 12 and 30 atm for a mixture representative of a syngas produced from biomass (0.29659% CO / 0.29659% H? / 0.15748% CO? / 0.08924% CH? / 0.20997% H?O / 0.95013% O? in 98% Ar (mol.%)) and for the same biomass-derived syngas mixture doped with 200 ppm of NH?. The importance of the various constituents on the ignition delay time was investigated by comparing the results with data from various baseline mixtures (H?/O?/Ar, H?/CO/O?/Ar and H?/CO/O?/Ar with one of the other constituent of the syngas (i.e. CO?, H?O, CH? or NH?)). The equivalence ratio was set to 0.5 during this study. Several recent detailed kinetics mechanisms from the literature were computed against these data, with fair agreement. Results showed that the mixture composition can have an important effect on the ignition delay time, with most of the effect being due to CH? addition through the reaction CH?+OH?CH?+H?O. The ammonia impurity had very little effect on the ignition delay time over the range of conditions studied.

  15. FLAMES AND XSHOOTER SPECTROSCOPY ALONG THE TWO BLUE STRAGGLER STAR SEQUENCES OF M30

    SciTech Connect (OSTI)

    Lovisi, L.; Mucciarelli, A.; Lanzoni, B.; Ferraro, F. R.; Dalessandro, E.

    2013-08-01

    We present spectroscopic observations acquired with FLAMES and XSHOOTER at the Very Large Telescope for a sample of 15 blue straggler stars (BSSs) in the globular cluster (GC) M30. The targets have been selected to sample the two BSS sequences discovered, with seven BSSs along the blue sequence and eight along the red one. No difference in the kinematical properties of the two groups of BSSs has been found. In particular, almost all the observed BSSs have projected rotational velocities lower than {approx}30 km s{sup -1}, with only one (blue) fast rotating BSS (>90 km s{sup -1}), identified as a W UMa binary. This rotational velocity distribution is similar to those obtained in 47 Tucanae and NGC 6397, while M4 remains the only GC studied so far that harbors a large fraction of fast rotating BSSs. All stars hotter than {approx}7800 K (regardless of the parent BSS sequence) show iron abundances larger than those measured from normal cluster stars, with a clear-cut trend with the effective temperature. This behavior suggests that particle transport mechanisms driven by radiative levitation occur in the photosphere of these stars, as already observed for the BSSs in NGC 6397. Finally, four BSSs belonging to the red sequence (not affected by radiative levitation) show a strong depletion of [O/Fe], with respect to the abundance measured in red giant branch and horizontal branch stars. This O-depletion is compatible with the chemical signature expected in BSSs formed by mass-transfer processes in binary systems, in agreement with the mechanism proposed for the formation of BSSs in the red sequence.

  16. shuttle-based system. Advanced capabilities of the new Rodent Habitat include providing

    E-Print Network [OSTI]

    Waliser, Duane E.

    help treat human disease on Earth. Rodent spaceflight experiments have contrib- uted significantly-duration rodent experiments in space. Such experiments will examine how microgravity affects the animals, providing information relevant to human spaceflight, discoveries in basic biology, and knowledge that can

  17. Identification of combustion intermediates in a low-pressure premixed laminar 2,5-dimethylfuran/oxygen/argon flame with tunable synchrotron photoionization

    SciTech Connect (OSTI)

    Wu, Xuesong; Huang, Zuohua; Wei, Lixia [State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an 710049 (China); Yuan, Tao; Zhang, Kuiwen [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029 (China)

    2009-07-15

    Low-pressure (4.0 kPa) premixed laminar 2,5-dimethylfuran (DMF)/oxygen/argon flame with an equivalence ratio of 2.0 was studied with tunable vacuum ultraviolet (VUV) synchrotron radiation photoionization and molecular-beam mass spectrometry. Photoionization mass spectra of DMF/O{sub 2}/Ar flame were recorded and the photoionization efficiency curves of the combustion intermediates were measured. Flame species, including isomeric intermediates, are identified by comparing the measured ionization energies with those reported in literatures or those calculated with Gaussian-3 procedure. More than 70 species have been detected, including furan and its derivatives, aromatics, and free radicals. Possible reaction pathways of DMF, 2-methylfuran, and furan are proposed based on the intermediates identified. DMF can be consumed by H-abstraction and pyrolysis reactions. 2-Methylfuran and furan can be consumed by H-abstraction, H-addition and pyrolysis reactions. (author)

  18. Large eddy simulation/conditional moment closure modeling of swirl-stabilized non-premixed flames with local extinction

    E-Print Network [OSTI]

    Zhang, Huangwei; Garmory, Andrew; Cavaliere, Davide E.; Mastorakos, Epaminondas

    2014-06-25

    University of Cambridge, Cambridge CB2 1PZ, United Kingdom Tel: +44 1223 332690, Fax: +44 1223 332662 Email: hz283@cam.ac.uk Colloquium topic: 5. Turbulent flames Alternative Colloquium topic: 11. IC engine and gas turbine combustion Paper length... -off                                                                * Corresponding author. E-mail: hz283@cam.ac.uk. Tel: +44 1223 332690.    2 1. Introduction Swirl flows are virtually ubiquitous in gas turbines [1-3]. However, the strong turbulent fluctuations due to the intense shear can lead to finite rate chemistry effects...

  19. Simulating flame lift-off characteristics of diesel and biodiesel fuels using detailed chemical-kinetic mechanisms and LES turbulence model.

    SciTech Connect (OSTI)

    Som, S; Longman, D. E.; Luo, Z; Plomer, M; Lu, T; Senecal, P.K.; Pomraning, E (Energy Systems); (Univ. of Connecticut); (CONVERGENT Science)

    2012-01-01

    Combustion in direct-injection diesel engines occurs in a lifted, turbulent diffusion flame mode. Numerous studies indicate that the combustion and emissions in such engines are strongly influenced by the lifted flame characteristics, which are in turn determined by fuel and air mixing in the upstream region of the lifted flame, and consequently by the liquid breakup and spray development processes. From a numerical standpoint, these spray combustion processes depend heavily on the choice of underlying spray, combustion, and turbulence models. The present numerical study investigates the influence of different chemical kinetic mechanisms for diesel and biodiesel fuels, as well as Reynolds-averaged Navier-Stokes (RANS) and large eddy simulation (LES) turbulence models on predicting flame lift-off lengths (LOLs) and ignition delays. Specifically, two chemical kinetic mechanisms for n-heptane (NHPT) and three for biodiesel surrogates are investigated. In addition, the RNG k-{epsilon} (RANS) model is compared to the Smagorinsky based LES turbulence model. Using adaptive grid resolution, minimum grid sizes of 250 {micro}m and 125 {micro}m were obtained for the RANS and LES cases respectively. Validations of these models were performed against experimental data from Sandia National Laboratories in a constant volume combustion chamber. Ignition delay and flame lift-off validations were performed at different ambient temperature conditions. The LES model predicts lower ignition delays and qualitatively better flame structures compared to the RNG k-{epsilon} model. The use of realistic chemistry and a ternary surrogate mixture, which consists of methyl decanoate, methyl 9-decenoate, and NHPT, results in better predicted LOLs and ignition delays. For diesel fuel though, only marginal improvements are observed by using larger size mechanisms. However, these improved predictions come at a significant increase in computational cost.

  20. Fuel-Specific Influences on the Composition of Reaction Intermediates in Premixed Flames of Three C5H10O2 Ester Isomers

    SciTech Connect (OSTI)

    Yang, B.; Cool, T. A.; Westbrook, Charles K.; Hansen, N.; Kohse-Hoinghaus, K.

    2011-01-01

    Measurements of the composition of reaction intermediates in low-pressure premixed flat flames of three simple esters, the methyl butanoate (MB), methyl isobutanoate (MIB), and ethyl propanoate (EP) isomers of C{sub 5}H{sub 10}O{sub 2}, enable further refinement and validation of a detailed chemical reaction mechanism originally developed in modeling studies of similar flames of methyl formate, methyl acetate, ethyl formate, and ethyl acetate. Photoionization mass spectrometry (PIMS), using monochromated synchrotron radiation, reveals significant differences in the compositions of key reaction intermediates between flames of the MB, MIB, and EP isomers studied under identical flame conditions. Detailed kinetic modeling describes how these differences are related to molecular structures of each of these isomers, leading to unique fuel destruction pathways. Despite the simple structures of these small esters, they contain structural functional groups expected to account for fuel-specific effects observed in the combustion of practical biodiesel fuels. The good agreement between experimental measurements and detailed reaction mechanisms applicable to these simple esters demonstrates that major features of each flame can be predicted with reasonable accuracy by building a hierarchical reaction mechanism based on three factors: (1) unimolecular decomposition of the fuel, especially by complex bond fission; (2) H-atom abstraction reactions followed by ?-scission of the resulting radicals, leading to nearly all of the intermediate species observed in each flame; (3) the rates of H-atom abstraction reactions for each alkoxy or alkyl group (i.e., methoxy, ethoxy, methyl, ethyl, propyl) are effectively the same as in other ester fuels with the same structural groups.

  1. Space System Architecture

    E-Print Network [OSTI]

    McManus, Dr. Hugh

    Final Report of SSPARC: the Space Systems, Policy, and Architecture Research Consortium (Thrust II and III)

  2. Dual-pump CARS temperature and major species concentration measurements in counter-flow methane flames using narrowband pump and broadband Stokes lasers

    SciTech Connect (OSTI)

    Thariyan, Mathew P.; Ananthanarayanan, Vijaykumar; Bhuiyan, Aizaz H.; Naik, Sameer V.; Gore, Jay P.; Lucht, Robert P.

    2010-07-15

    Dual-pump coherent anti-Stokes Raman scattering (CARS) is used to measure temperature and species profiles in representative non-premixed and partially-premixed CH{sub 4}/O{sub 2}/N{sub 2} flames. A new laser system has been developed to generate a tunable single-frequency beam for the second pump beam in the dual-pump N{sub 2}-CO{sub 2} CARS process. The second harmonic output ({proportional_to}532 nm) from an injection-seeded Nd:YAG laser is used as one of the narrowband pump beams. The second single-longitudinal-mode pump beam centered near 561 nm is generated using an injection-seeded optical parametric oscillator, consisting of two non-linear {beta}-BBO crystals, pumped using the third harmonic output ({proportional_to}355 nm) of the same Nd:YAG laser. A broadband dye laser (BBDL), pumped using the second harmonic output of an unseeded Nd:YAG laser, is employed to produce the Stokes beam centered near 607 nm with full-width-at-half-maximum of {proportional_to}250 cm{sup -1}. The three beams are focused between two opposing nozzles of a counter-flow burner facility to measure temperature and major species concentrations in a variety of CH{sub 4}/O{sub 2}/N{sub 2} non-premixed and partially-premixed flames stabilized at a global strain rate of 20 s{sup -1} at atmospheric-pressure. For the non-premixed flames, excellent agreement is observed between the measured profiles of temperature and CO{sub 2}/N{sub 2} concentration ratios with those calculated using an opposed-flow flame code with detailed chemistry and molecular transport submodels. For partially-premixed flames, with the rich side premixing level beyond the stable premixed flame limit, the calculations overestimate the distance between the premixed and the non-premixed flamefronts. Consequently, the calculated temperatures near the rich, premixed flame are higher than those measured. Accurate prediction of the distance between the premixed and the non-premixed flames provides an interesting challenge for future computations. (author)

  3. Sequencing and Scheduling in Coil Coating with Shuttles Wiebke H ohn # Felix G. K onig Marco E. L ubbecke Rolf H. M ohring

    E-Print Network [OSTI]

    Nabben, Reinhard

    Sequencing and Scheduling in Coil Coating with Shuttles Wiebke HË? ohn # Felix G. KË? onig Marco E. L problem in integrated steel production. A sequence of coils of sheet metal needs to be color coated. In most coating stages one can choose between two parallel color tanks. This can either reduce the number

  4. Evaluation of metallic foils for preconcentration of sulfur-containing gases with subsequent flash desorption/flame photometric detection

    SciTech Connect (OSTI)

    Kagel, R.A.; Farwell, S.O.

    1986-05-01

    Ag, Ni, Pd, Pt, Rh, and W foils were examined for their collective efficiencies toward seven sulfur-containing gases, i.e., H/sub 2/S, CH/sub 3/SH, CH/sub 3/SCH/sub 3/, CH/sub 3/SSCH/sub 3/, CS/sub 2/, COS, and SO/sub 2/. Low- and sub-part-per-billion (v/v) concentrations of these individual sulfur gases in air were drawn through a fluorocarbon resin cell containing a mounted 30-mm x 7-mm x 0.025-mm metal foil. The preconcentrated species were then thermally desorbed by a controlled pulse of current through the foil. The desorbed sample plug was swept in precleaned zero air from the fluorocarbon resin cell to a flame photometric detector. Sampling flow rate, ambient temperature, sample humidity, and common oxidants were examined for their effects on the collection efficiencies of these sulfur compounds on platinum and palladium foils. Analytical characteristics of this metal foil collection/flash desorption/flame photometric detector (MFC/FD/FPD) technique include a sulfur gas detectability of less than 50 pptr (parts per trillion) (v/v), a response repeatability of at least 95%, and field portable collection cells and instrumentation. The results are discussed both in terms of potential analytical applications of MFC/FD/FPD and in terms of their relationship to characterized models of gas adsorption on solid surfaces. 33 references, 6 figures, 3 tables.

  5. A Lean Methane Prelixed Laminar Flame Doped witg Components of Diesel Fuel. Part I: n)Butylbenzene

    E-Print Network [OSTI]

    Pousse, Emir; Fournet, René; Battin-Leclerc, Frédérique; 10.1016/j.combustflame.2008.09.012

    2009-01-01

    To better understand the chemistry involved during the combustion of components of diesel fuel, the structure of a laminar lean premixed methane flame doped with n-butylbenzene has been investigated. The inlet gases contained 7.1% (molar) of methane, 36.8% of oxygen and 0.96% of n-butylbenzene corresponding to an equivalence ratio of 0.74 and a ratio C10H14 / CH4 of 13.5%. The flame has been stabilized on a burner at a pressure of 6.7 kPa using argon as diluent, with a gas velocity at the burner of 49.2 cm/s at 333 K. Quantified species included the usual methane C0-C2 combustion products, but also 16 C3-C5 hydrocarbons, 7 C1-C3 oxygenated compounds, as well as 20 aromatic products, namely benzene, toluene, phenylacetylene, styrene, ethylbenzene, xylenes, allylbenzene, propylbenzene, cumene, methylstyrenes, butenylbenzenes, indene, indane, naphthalene, phenol, benzaldehyde, anisole, benzylalcohol, benzofuran, and isomers of C10H10 (1-methylindene, dihydronaphtalene, butadienylbenzene). A new mechanism for the...

  6. Simultaneous imaging of OH, formaldehyde, and temperature of turbulent nonpremixed jet flames in a heated and diluted coflow

    SciTech Connect (OSTI)

    Medwell, Paul R.; Kalt, Peter A.M.; Dally, Bassam B. [School of Mechanical Engineering, The University of Adelaide, S.A. 5005 (Australia)

    2007-01-15

    This paper reports measurements in turbulent nonpremixed CH{sub 4}/H{sub 2} jet flames issuing into a heated and highly diluted coflow. These conditions emulate those of moderate or intense low-oxygen-dilution (MILD) combustion. The spatial distribution of the hydroxyl radical (OH), formaldehyde (H{sub 2}CO), and temperature, imaged using planar laser-induced fluorescence and Rayleigh scattering laser diagnostic techniques, are measured and presented. Comparisons are made between three jet Reynolds numbers and two coflow O{sub 2} levels. Measurements are taken at two downstream locations. The burner used in this work facilitates the additional study on the effects of the entrainment of surrounding air on the flame structure at downstream locations. Reducing the coflow oxygen level is shown to lead to a suppression of OH as a result of the reduced temperatures in the reaction zone. Decreasing the oxygen level of the coflow also results in a broadening of the OH distribution. At downstream locations, the surrounding air mixes with the jet and coflow. The subsequent drop in the temperature of the oxidant stream can lead to a rupture of the OH layer. Localized extinction allows premixing of the fuel with the surrounding air. The result is an increase in the reaction rate, highlighting the need for homogeneous mixing to maintain MILD combustion conditions. (author)

  7. NO{sub 2} gas sensing of flame-made Pt-loaded WO{sub 3} thick films

    SciTech Connect (OSTI)

    Samerjai, Thanittha [Nanoscience and Nanotechnology Program, Faculty of Graduate School, Chiang Mai University, Chiang Mai 50200 (Thailand); Tamaekong, Nittaya [Program in Materials Science, Faculty of Science, Maejo University, Chiang Mai 50290 (Thailand); Liewhiran, Chaikarn [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Wisitsoraat, Anurat [Nanoelectronics and MEMS Laboratory, National Electronics and Computer Technology Center, Klong Luang, Pathumthani 12120 (Thailand); Phanichphant, Sukon, E-mail: sphanichphant@yahoo.com [Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2014-06-01

    Unloaded WO{sub 3} and 0.25–1.0 wt% Pt-loaded WO{sub 3} nanoparticles for NO{sub 2} gas detection were synthesized by flame spray pyrolysis (FSP) and characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The BET surface area (SSA{sub BET}) of the nanoparticles was measured by nitrogen adsorption. The NO{sub 2} sensing properties of the sensors based on unloaded and Pt-loaded WO{sub 3} nanoparticles were investigated. The results showed that the gas sensing properties of the Pt-loaded WO{sub 3} sensors were excellent to those of the unloaded one. Especially, 0.25 wt% Pt-loaded WO{sub 3} sensor showed highest response to NO{sub 2} than the others at low operating temperature of 150 °C. - Graphical abstract: The response of 0.25 wt% Pt-loaded WO3 sensor was 637 towards NO{sub 2} concentration of 10 ppm at 150 °C. - Highlights: • Unloaded and Pt-loaded WO{sub 3} nanoparticles for NO{sub 2} gas detection were synthesized by flame spray pyrolysis (FSP). • Gas sensing properties of the Pt-loaded WO{sub 3} sensors were excellent to those of the unloaded one. • 0.25 wt% Pt-loaded WO{sub 3} sensor showed highest response to NO{sub 2} at low operating temperature of 150 °C.

  8. Spreading of thermonuclear flames on the neutron star in SAX J1808.4-3658: an observational tool

    E-Print Network [OSTI]

    Sudip Bhattacharyya; Tod E. Strohmayer

    2006-04-03

    We analyse archival Rossi X-Ray Timing Explorer (RXTE) proportional counter array (PCA) data of thermonuclear X-ray bursts from the 2002 outburst of the accreting millisecond pulsar SAX J1808.4-3658. We present evidence of nonmonotonic variations of oscillation frequency during burst rise, and correlations among the time evolution of the oscillation frequency, amplitude, and the inferred burning region area. We also discuss that the amplitude and burning region area evolutions are consistent with thermonuclear flame spreading on the neutron star surface. Based on this discussion, we infer that for the 2002 Oct. 15 thermonuclear burst, the ignition likely occured in the mid-latitudes, the burning region took ~ 0.2 s to nearly encircle the equatorial region of the neutron star, and after that the lower amplitude oscillation originated from the remaining asymmetry of the burning front in the same hemisphere where the burst ignited. Our observational findings and theoretical discussion indicate that studies of the evolution of burst oscillation properties during burst rise can provide a powerful tool to understand thermonuclear flame spreading on neutron star surfaces under extreme physical conditions.

  9. Determination of total biogenic sulfur gases by filter/flash vaporization/flame photometry

    SciTech Connect (OSTI)

    Farwell, S.O.; Liebowitz, D.P.; Kagel, R.A.; Adams, D.F.

    1980-12-01

    Complete conversion of H/sub 2/S, COS, CH/sub 3/SH, CH/sub 3/SCH/sub 3/, CS/sub 2/, and CH/sub 3/SSCH/sub 3/ to SO/sub 2/ has been shown to occur in a quartz tube held at a furnace temperature of 1050/sup 0/C for sample air flows from 30 mL/min to 2.8 L/min. The resultant SO/sub 2/-containing air flow is passed through an inline, precleaned Gelman Spectrograde filter which collects an average of 1.5 +- 0.3 ..mu..g of S/47 mm filter prior to SO/sub 2/ breakthrough. The sulfur collected on the filters is extracted with a recovery of 100 +- 3%. Final quantitative determinations of the sulfur in the filter extracts are performed via the flash vaporization/flame photometric (FV/FPD) technique using platinum boats. Equivalent FV/FPD linear responses were observed for H/sub 2/SO/sub 4/, Na/sub 2/SO/sub 4/, K/sub 2/SO/sub 4/, and (NH/sub 4/)/sub 2/SO/sub 4/ standards in the range of 0.4 to 12 ng of S. Repeated analyses of sulfate standards showed a relative standard deviation (RSD) = +-7.0%. Experimental results obtained for NaHCO/sub 3/, Na/sub 2/CO/sub 3/, NaOH, NaCl, KHCO/sub 3/, K/sub 2/CO/sub 3/, KOH, NH/sub 4/HCO/sub 3/, (NH/sub 4/)/sub 2/CO/sub 3/, NH/sub 3/(aq), FeCl/sub 3/, MnCl/sub 2/, and Na/sub 2/HgCl/sub 4/ as chemical impregnants in glass fiber filters for SO/sub 2/ collection and their compatibility with the FV/FPD system are also described.

  10. Social Media: Space Weather #SpaceWeather

    E-Print Network [OSTI]

    causing blackouts in rare cases. To learn about space weather and impacts to the electric grid visit on the Power Grid Space Weather and the Aurora Borealis What are Solar Flares? What are Coronal Mass we do. Satellite communications, GPS applications, and the electric power grid provide the backbone

  11. The Space Shuttle design presented many thermal insulation challenges. The system not only had to perform well, it had to integrate

    E-Print Network [OSTI]

    to exceedingly high temperatures and needed reusable, lightweight, low-cost thermal protection. The vehicle also Steinetz Ice Detection Prevents Catastrophic Problems Charles Stevenson Aerogel-based Insulation System broke apart and collided with the surface of the vehicle, they recombined in an exothermic reaction

  12. Measurement of Turbulent Flame Speeds of Hydrogen and Natural Gas Blends (C1-C5 Alkanes) using a Newly Developed Fan-Stirred Vessel 

    E-Print Network [OSTI]

    Ravi, Sankaranarayana

    2014-05-06

    A fan-stirred flame speed vessel was developed at Texas A&M University to conduct turbulent combustion studies. Four high-speed impellers were installed in a central-symmetric pattern at the central circumference of an existing cylindrical laminar...

  13. Journal of Statistical Physics, Vol. 90, Nos. 5/6, 1998 We study the nucleation and growth of flame fronts in slow combustion. This

    E-Print Network [OSTI]

    Grant, Martin

    fronts in slow combustion. This is modeled by a set of reaction-diffusion equations for the temperature: Nucleation; reaction-diffusion systems; flame fronts. Nucleation, Growth, and Scaling in Slow Combustion applied to understand some aspects of slow combustion. We use a phase-field model of two coupled reaction

  14. Space Science and Applications

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    the first measurements of Earth's space radiation environment and the discovery of gamma-ray bursts. The majority of ISR-1 staff hold PhDs in Space Physics, Nuclear Physics, or...

  15. Senior Space Camp 2015, Andya Space Center, Norway Senior Space Camp 2015

    E-Print Network [OSTI]

    Gerhardy, Philipp

    Senior Space Camp 2015, Andøya Space Center, Norway Senior Space Camp 2015 Arrangører: Nasjonalt deltakere Sted: Andøya Space Center (ASC), Andøya, Norway Undervisning: Programmet er delt mellom, Andøya Space Center, Norway FORELESERE / ADMINISTRASJON Tittel Etternavn Fornavn Initialer Organisasjon

  16. Fibers and fabrics with insulating, water-proofing, and flame-resistant properties

    DOE Patents [OSTI]

    Hrubesh, Lawrence W.; Poco, John F.; Coronado, Paul R.

    2004-04-20

    Fibers, and fabrics produced from the fibers, are made water repellent, fire-retardant and/or thermally insulating by filling void spaces in the fibers and/or fabrics with a powdered material. When the powder is sufficiently finely divided, it clings tenaciously to the fabric's fibers and to itself, resisting the tendency to be removed from the fabric.

  17. TANK SPACE OPTIONS REPORT

    SciTech Connect (OSTI)

    WILLIS WL; AHRENDT MR

    2009-08-11

    Since this report was originally issued in 2001, several options proposed for increasing double-shell tank (DST) storage space were implemented or are in the process of implementation. Changes to the single-shell tank (SST) waste retrieval schedule, completion of DST space saving options, and the DST space saving options in progress have delayed the projected shortfall of DST storage space from the 2007-2011 to the 2018-2025 timeframe (ORP-11242, River Protection Project System Plan). This report reevaluates options from Rev. 0 and includes evaluations of new options for alleviating projected restrictions on SST waste retrieval beginning in 2018 because of the lack of DST storage space.

  18. Artificial neural network implementation of chemistry with pdf simulation of H{sub 2}/CO{sub 2} flames

    SciTech Connect (OSTI)

    Christo, F.C.; Masri, A.R.; Nebot, E.M.

    1996-09-01

    A novel approach using artificial neural networks for representing chemical reactions is developed and successfully implemented with a modeled velocity-scalar joint pdf transport equation for H{sub 2}CO{sub 2} turbulent jet diffusion flames. The chemical kinetics are represented using a three-step reduced mechanism, and the transport equation is solved by a Monte Carlo method. A detailed analysis of computational performance and a comparison between the neural network approach and other methods used to represent the chemistry, namely the look-up table, or the direct integration procedures, are presented. A multilayer perceptron architecture is chosen for the neural network. The training algorithm is based on a back-propagation supervised learning procedure with individual momentum terms and adaptive learning rate adjustment for the weights matrix. A new procedure for the selection of training samples using dynamic randomization is developed and is aimed at reducing the possibility of the network being trapped in a local minimum. This algorithm achieved an impressive acceleration in convergence compared with the use of a fixed set of selected training samples. The optimization process of the neural network is discussed in detail. The feasibility of using neural network models to represent highly nonlinear chemical reactions is successfully illustrated. The prediction of the flow field and flame characteristics using the neural network approach is in good agreement with those obtained using other methods, and is also in reasonable agreement with the experimental data. The computational benefits of the neural network approach over the look-up table and the direct integration methods, both in CPU time and RAM storage requirements are not great for a chemical mechanisms of less than three reactions. The neural network approach becomes superior, however, for more complex reaction schemes.

  19. HTS Magnets for Advanced Magnetoplasma Space Propulsion Applications

    SciTech Connect (OSTI)

    Carte, M.D.; Chang-Diaz, F.R. Squire, J.P.; Schwenterly, S.W.

    1999-07-12

    Plasma rockets are being considered for both Earth-orbit and interplanetary missions because their extremely high exhaust velocity and ability to modulate thrust allow very efficient use of propellant mass. In such rockets, a hydrogen or helium plasma is RF-heated and confined by axial magnetic fields produced by coils around the plasma chamber. HTS coils cooled by the propellant are desirable to increase the energy efficiency of the system. We describe a set of prototype high-temperature superconducting (HTS) coils that are being considered for the VASIMR ( Variable Specific Impulse Magnetoplasma Rocket) thruster proposed for testing on the Radiation Technology Demonstration (RTD) satellite. Since this satellite will be launched by the Space Shuttle, for safety reasons liquid helium will be used as propellant and coolant. The coils must be designed to operate in the space environment at field levels of 1 T. This generates a unique set of requirements. Details of the overall winding geometry and current density, as well as the challenging thermal control aspects associated with a compact, minimum weight design will be discussed.

  20. Space Systems Finland 1 Deployment in the Space Sector

    E-Print Network [OSTI]

    Southampton, University of

    © Space Systems Finland 1 Deployment in the Space Sector #12;© Space Systems Finland 2 SW Constraints Design Requirements User Requirements SW Requirements #12;© Space Systems Finland 3 The space, but there is no viable alternative · Many requirements are not testable #12;© Space Systems Finland 4 SSF OBJECTIVES

  1. UCL DEPARTMENT OF SPACE & CLIMATE PHYSICS SPACE PLASMA PHYSICS GROUP

    E-Print Network [OSTI]

    Anand, Mahesh

    UCL DEPARTMENT OF SPACE & CLIMATE PHYSICS SPACE PLASMA PHYSICS GROUP ESA Lunar Lander ­ L-DEPP C.J. Owen and D.O. Kataria UCL/MSSL #12;UCL DEPARTMENT OF SPACE & CLIMATE PHYSICS SPACE PLASMA PHYSICS GROUP is LEIA necessary? · Potential UK benefits · Summary #12;UCL DEPARTMENT OF SPACE & CLIMATE PHYSICS SPACE

  2. Matter: Space without Time

    E-Print Network [OSTI]

    Yousef Ghazi-Tabatabai

    2012-11-19

    While Quantum Gravity remains elusive and Quantum Field Theory retains the interpretational difficulties of Quantum Mechanics, we have introduced an alternate approach to the unification of particles, fields, space and time, suggesting that the concept of matter as space without time provides a framework which unifies matter with spacetime and in which we anticipate the development of complete theories (ideally a single unified theory) describing observed 'particles, charges, fields and forces' solely with the geometry of our matter-space-time universe.

  3. Total Space Heat-

    Gasoline and Diesel Fuel Update (EIA)

    Revised: December, 2008 Total Space Heat- ing Cool- ing Venti- lation Water Heat- ing Light- ing Cook- ing Refrig- eration Office Equip- ment Com- puters Other All Buildings...

  4. Total Space Heat-

    Gasoline and Diesel Fuel Update (EIA)

    Released: September, 2008 Total Space Heat- ing Cool- ing Venti- lation Water Heat- ing Light- ing Cook- ing Refrig- eration Office Equip- ment Com- puters Other All Buildings*...

  5. Newtonian Lorentz Metric Spaces

    E-Print Network [OSTI]

    Costea, Serban

    2011-01-01

    This paper studies Newtonian Sobolev-Lorentz spaces. We prove that these spaces are Banach. We also study the global p,q-capacity and the p,q-modulus of families of rectifiable curves. Under some additional assumptions (that is, the space carries a doubling measure and a weak Poincare inequality) and some restrictions on q, we show that the Lipschitz functions are dense in those spaces. Moreover, in the same setting we also show that the p,q-capacity is Choquet provided that q is strictly greater than 1. We provide a counterexample for the density result of Lipschitz functions in the Euclidean setting.

  6. AB Space Engine

    E-Print Network [OSTI]

    Alexander Bolonkin

    2008-03-02

    On 4 January 2007 the author published the article Wireless Transfer of Electricity in Outer Space in http://arxiv.org wherein he offered and researched a new revolutionary method of transferring electric energy in space. In that same article, he offered a new engine which produces a large thrust without throwing away large amounts of reaction mass (unlike the conventional rocket engine). In the current article, the author develops the theory of this kind of impulse engine and computes a sample project which shows the big possibilities opened by this new AB-Space Engine. The AB-Space Engine gets the energy from ground-mounted power; a planet electric station can transfer electricity up to 1000 millions (and more) of kilometers by plasma wires. Author shows that AB-Space Engine can produce thrust of 10 tons (and more). That can accelerate a space ship to some thousands of kilometers/second. AB-Space Engine has a staggering specific impulse owing to the very small mass expended. The AB-Space Engine reacts not by expulsion of its own mass (unlike rocket engine) but against the mass of its planet of origin (located perhaps a thousand of millions of kilometers away) through the magnetic field of its plasma cable. For creating this plasma cable the AB-Space Engine spends only some kg of hydrogen.

  7. Passive solar space heating

    SciTech Connect (OSTI)

    Balcomb, J.D.

    1980-01-01

    An overview of passive solar space heating is presented indicating trends in design, new developments, performance measures, analytical design aids, and monitored building results.

  8. Neutron Tomography and Space

    E-Print Network [OSTI]

    Egbert, Hal; Walker, Ronald; Flocchini, R.

    2007-01-01

    Kevin Shields, “Optimization of neutron tomography for rapidNEUTRON TOMOGRAPHY AND SPACE Hal Egbert, Ronald Walker, R.industrial applications[1]. Neutron Computed Tomography was

  9. Contestation of Space

    E-Print Network [OSTI]

    Alkhalili, Nura

    2012-01-01

    city and a neighboring refugee camp. It seeks to narrate thechange, and the neighboring refugee camp. The public parkoccurring in Ramallah between refugee and non-refugee space.

  10. Multimegawatt space power reactors

    SciTech Connect (OSTI)

    Dearien, J.A.; Whitbeck, J.F.

    1989-01-01

    In response to the need of the Strategic Defense Initiative (SDI) and long range space exploration and extra-terrestrial basing by the National Air and Space Administration (NASA), concepts for nuclear power systems in the multi-megawatt levels are being designed and evaluated. The requirements for these power systems are being driven primarily by the need to minimize weight and maximize safety and reliability. This paper will discuss the present requirements for space based advanced power systems, technological issues associated with the development of these advanced nuclear power systems, and some of the concepts proposed for generating large amounts of power in space. 31 figs.

  11. Space Fiesta - 1 

    E-Print Network [OSTI]

    Unknown

    2011-08-17

    We study the geometric classi?cation of Banach spaces via Lipschitz, uniformly continuous, and coarse mappings. We prove that a Banach space which is uniformly homeomorphic to a linear quotient of lp is itself a linear quotient of lp when p<2...

  12. AB Space Engine

    E-Print Network [OSTI]

    Bolonkin, Alexander

    2008-01-01

    On 4 January 2007 the author published the article Wireless Transfer of Electricity in Outer Space in http://arxiv.org wherein he offered and researched a new revolutionary method of transferring electric energy in space. In that same article, he offered a new engine which produces a large thrust without throwing away large amounts of reaction mass (unlike the conventional rocket engine). In the current article, the author develops the theory of this kind of impulse engine and computes a sample project which shows the big possibilities opened by this new AB-Space Engine. The AB-Space Engine gets the energy from ground-mounted power; a planet electric station can transfer electricity up to 1000 millions (and more) of kilometers by plasma wires. Author shows that AB-Space Engine can produce thrust of 10 tons (and more). That can accelerate a space ship to some thousands of kilometers/second. AB-Space Engine has a staggering specific impulse owing to the very small mass expended. The AB-Space Engine reacts not b...

  13. Moduli Spaces and Grassmannian

    E-Print Network [OSTI]

    Jia-Ming Liou; Albert Schwarz

    2012-04-12

    We calculate the homomorphism of the cohomology induced by the Krichever map of moduli spaces of curves into infinite-dimensional Grassmannian. This calculation can be used to compute the homology classes of cycles on moduli spaces of curves that are defined in terms of Weierstrass points.

  14. SPACE TECHNOLOGY Actual Estimate

    E-Print Network [OSTI]

    technology readiness of new missions, mitigate their technological risks, improve the quality of cost estimates, and thereby contribute to better overall mission cost management..." Space Technology investmentsSPACE TECHNOLOGY TECH-1 Actual Estimate Budget Authority (in $ millions) FY 2011 FY 2012 FY 2013 FY

  15. Atoms for space

    SciTech Connect (OSTI)

    Buden, D.

    1990-10-01

    Nuclear technology offers many advantages in an expanded solar system space exploration program. These cover a range of possible applications such as power for spacecraft, lunar and planetary surfaces, and electric propulsion; rocket propulsion for lunar and Mars vehicles; space radiation protection; water and sewage treatment; space mining; process heat; medical isotopes; and self-luminous systems. In addition, space offers opportunities to perform scientific research and develop systems that can solve problems here on Earth. These might include fusion and antimatter research, using the Moon as a source of helium-3 fusion fuel, and manufacturing perfect fusion targets. In addition, nuclear technologies can be used to reduce risk and costs of the Space Exploration Initiative. 1 fig.

  16. A lean methane premixed laminar flame doped with components of diesel fuel part III: Indane and comparison between n-butylbenzene, n-propylcyclohexane and indane

    SciTech Connect (OSTI)

    Pousse, E.; Tian, Z.Y.; Glaude, P.A.; Fournet, R.; Battin-Leclerc, F. [Laboratoire des Reactions et de Genie des Procedes, CNRS, Nancy Universite, 1 rue Grandville, BP 20451, 54001 NANCY Cedex (France)

    2010-07-15

    To better understand the chemistry of the combustion of components of diesel fuel, the structure of a laminar lean premixed methane flame doped with indane has been investigated. The inlet gases contained 7.1% (molar) of methane, 36.8% of oxygen and 0.9% of indane corresponding to an equivalence ratio of 0.67 and a ratio C{sub 10}H{sub 14}/CH{sub 4} of 12.8%. The flame has been stabilized on a burner at a pressure of 6.7 kPa (50 Torr) using argon as diluent, with a gas velocity at the burner of 49.1 cm s{sup -1} at 333 K. Quantified species included the usual methane C{sub 0}-C{sub 2} combustion products, but also 16 C{sub 3}-C{sub 5} non-aromatic hydrocarbons, 6 C{sub 1}-C{sub 3} non-aromatic oxygenated compounds, as well as 22 aromatic products, namely benzene, toluene, xylenes, phenylacetylene, ethylbenzene, styrene, propenylbenzene, allylbenzene, n-propylbenzene, methylstyrenes, ethyltoluenes, trimethylbenzenes, n-butylbenzene, dimethylethylbenzene, indene, methylindenes, methylindane, benzocyclobutene, naphthalene, phenol, benzaldehyde, and benzofuran. A new mechanism for the oxidation of indane was proposed whose predictions were in satisfactory agreement with measured species profiles in both flames and jet-stirred reactor experiments. The main reaction pathways of consumption of indane have been derived from flow rate analyses in the two types of reactors. A comparison of the effect of the addition of three components of diesel fuel, namely indane, n-butylbenzene and n-propylcyclohexane (parts I and II of this series of paper), on the structure of a laminar lean premixed methane flame is also presented. (author)

  17. Syngas production from butane using a flame-made Rh/Ce0.5Zr0.5O2 Nico Hotz a

    E-Print Network [OSTI]

    Daraio, Chiara

    Syngas production from butane using a flame-made Rh/Ce0.5Zr0.5O2 catalyst Nico Hotz a , Michael J the production of H2- and CO-rich syngas from butane was investigated for different Rh loadings (0­2.0 wt% Rh for a temperature range from 225 to 750 8C. The main goal of this study was the efficient processing of butane

  18. Experimental and computational study of methane counterflow diffusion flames perturbed by trace amounts of either jet fuel or a 6-component surrogate under non-sooting conditions

    SciTech Connect (OSTI)

    Bufferand, H.; Tosatto, L.; La Mantia, B.; Smooke, M.D.; Gomez, A. [Department of Mechanical Engineering, Yale Center for Combustion Studies, Yale University, New Haven, CT 06520-8286 (United States)

    2009-08-15

    The chemical structure of a methane counterflow diffusion flame and of the same flame doped with 1000 ppm (molar) of either jet fuel or a 6-component jet fuel surrogate was analyzed experimentally, by gas sampling via quartz microprobes and subsequent GC/MS analysis, and computationally using a semi-detailed kinetic mechanism for the surrogate blend. Conditions were chosen to ensure that all three flames were non-sooting, with identical temperature profiles and stoichiometric mixture fraction, through a judicious selection of feed stream composition and strain rate. The experimental dataset provides a glimpse of the pyrolysis and oxidation behavior of jet fuel in a diffusion flame. The jet fuel initial oxidation is consistent with anticipated chemical kinetic behavior, based on thermal decomposition of large alkanes to smaller and smaller fragments and the survival of ring-stabilized aromatics at higher temperatures. The 6-component surrogate captures the same trend correctly, but the agreement is not quantitative with respect to some of the aromatics such as benzene and toluene. Various alkanes, alkenes and aromatics among the jet fuel components are either only qualitatively characterized or could not be identified, because of the presence of many isomers and overlapping spectra in the chromatogram, leaving 80% of the carbon from the jet fuel unaccounted for in the early pyrolysis history of the parent fuel. Computationally, the one-dimensional code adopted a semi-detailed kinetic mechanism for the surrogate blend that is based on an existing hierarchically constructed kinetic model for alkanes and simple aromatics, extended to account for the presence of tetralin and methylcyclohexane as reference fuels. The computational results are in reasonably good agreement with the experimental ones for the surrogate behavior, with the greatest discrepancy in the concentrations of aromatics and ethylene. (author)

  19. An experimental investigation of ethylene/O{sub 2}/diluent mixtures: Laminar flame speeds with preheat and ignition delays at high pressures

    SciTech Connect (OSTI)

    Kumar, Kamal; Mittal, Gaurav; Sung, Chih-Jen [Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH 44106 (United States); Law, Chung K. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States)

    2008-05-15

    The atmospheric pressure laminar flame speeds of premixed ethylene/O{sub 2}/N{sub 2} mixtures were experimentally measured over equivalence ratios ranging from 0.5 to 1.4 and mixture preheat temperatures varying from 298 to 470 K in a counterflow configuration. Ignition delay measurements were also conducted for ethylene/O{sub 2}/N{sub 2}/Ar mixtures using a rapid compression machine at compressed pressures from 15 to 50 bar and in the compressed temperature range from 850 to 1050 K. The experimental laminar flame speeds and ignition delays were then compared to the computed values using two existing chemical kinetic mechanisms. Results show that while the laminar flame speeds are reasonably predicted at room temperature conditions, the discrepancy becomes larger with increasing preheat temperature. A comparison of experimental and computational ignition delay times was also conducted and discussed. Sensitivity analysis further shows that the ignition delay is highly sensitive to the reactions of the vinyl radical with molecular oxygen. The reaction of ethylene with the HO{sub 2} radical was also found to be important for autoignition under the current experimental conditions. (author)

  20. Effect of fuel rate and annealing process of LiFePO{sub 4} cathode material for Li-ion batteries synthesized by flame spray pyrolysis method

    SciTech Connect (OSTI)

    Halim, Abdul; Setyawan, Heru; Machmudah, Siti; Nurtono, Tantular; Winardi, Sugeng

    2014-02-24

    In this study the effect of fuel rate and annealing on particle formation of LiFePO{sub 4} as battery cathode using flame spray pyrolysis method was investigated numerically and experimentally. Numerical study was done using ANSYS FLUENT program. In experimentally, LiFePO{sub 4} was synthesized from inorganic aqueous solution followed by annealing. LPG was used as fuel and air was used as oxidizer and carrier gas. Annealing process attempted in inert atmosphere at 700°C for 240 min. Numerical result showed that the increase of fuel rate caused the increase of flame temperature. Microscopic observation using Scanning Electron Microscopy (SEM) revealed that all particles have sphere and polydisperse. Increasing fuel rate caused decreasing particle size and increasing particles crystallinity. This phenomenon attributed to the flame temperature. However, all produced particles still have more amorphous phase. Therefore, annealing needed to increase particles crystallinity. Fourier Transform Infrared (FTIR) analysis showed that all particles have PO4 function group. Increasing fuel rate led to the increase of infrared spectrum absorption corresponding to the increase of particles crystallinity. This result indicated that phosphate group vibrated easily in crystalline phase. From Electrochemical Impedance Spectroscopy (EIS) analysis, annealing can cause the increase of Li{sup +} diffusivity. The diffusivity coefficient of without and with annealing particles were 6.84399×10{sup ?10} and 8.59888×10{sup ?10} cm{sup 2} s{sup ?1}, respectively.

  1. The combustion chemistry of a fuel tracer: Measured flame speeds and ignition delays and a detailed chemical kinetic model for the oxidation of acetone

    SciTech Connect (OSTI)

    Pichon, S.; Black, G.; Simmie, J.M.; Curran, H.J.; Chaumeix, N.; Yahyaoui, M.; Donohue, R.

    2009-02-15

    Acetone ignition delay and stretch-free laminar flame speed measurements have been carried out and a kinetic model has been developed to simulate these and literature data for acetone and for ketene, which was found to be an important intermediate in its oxidation. The mechanism has been based on one originally devised for dimethyl ether and modified through validation of the hydrogen, carbon monoxide and methane sub-mechanisms. Acetone oxidation in argon was studied behind reflected shock waves in the temperature range 1340-1930 K, at 1 atm and at equivalence ratios of 0.5, 1 and 2; it is also shown that the addition of up to 15% acetone to a stoichiometric n-heptane mixture has no effect on the measured ignition delay times. Flame speeds at 298 K and 1 atm of pure acetone in air were measured in a spherical bomb; a maximum flame speed of {proportional_to}35 cm s{sup -1} at {phi}=1.15 is indicated. (author)

  2. Radiative properties of char, fly-ash, and soot particles in coal flames. Technical progress report, second year, October 1994--December 1994

    SciTech Connect (OSTI)

    Menguec, M.P.; Manickavasagam, S.; Govindan, R.; Ghosal, S.

    1995-04-01

    In large-scale coal-fired flames, radiative transfer is significant as a large portion of the energy generated during the char pyrolysis and soot oxidation is transferred to the surroundings by radiation (due to emission). The relatively cold gases and particles which are not burning yet are heated by this incoming energy (absorption), which may have originated not only from the immediate surroundings of the control volume of interest but the entire flame. It is obvious that if the emission and absorption of radiation in such a flame are not accounted for correctly, it is not possible to determine other underlying phenomena with accuracy, as the fundamental principle of conservation of energy would be violated. In order to consider the effect of radiation heat transfer in coal-fired furnaces, we have to (1) model the radiative transfer equation to satisfy the conservation of radiant energy principle; (2) use the correct radiative properties of combustion gases and particles; (3) account for the interaction of radiation with the flow and energy equations. The radiative properties for a participating medium of spherical particles can be expressed in terms of the spectral absorption, extinction, and scattering efficiencies and the phase function for a single particle, and can be calculated from the Lorenz-Mie theory. For small size particles, the expressions are based on the Rayleigh limit of Lorenz-Mie theory, and are significantly simpler. The details are readily available in the literature.

  3. Characterization of MtoD from Sideroxydans lithotrophicus: a cytochrome c electron shuttle used in lithoautotrophic growth

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Beckwith, Christopher R.; Edwards, Marcus J.; Lawes, Matthew; Shi, Liang; Butt, Julea N.; Richardson, David J.; Clarke, Thomas A.

    2015-04-28

    The autotrophic Sideroxydans lithotrophicus ES-1 can grow by coupling the oxidation of ferrous iron to the reduction of oxygen. Soluble ferrous iron is oxidized at the surface of the cell by an MtoAB porin-cytochrome complex that functions as an electron conduit through the outer membrane. Electrons are then transported to the cytoplasmic membrane where they are used to generate proton motive force (PMF) (for ATP synthesis) and NADH for autotrophic processes such as carbon fixation. As part of the mtoAB gene cluster, S. lithotrophicus also contains the gene mtoD that is proposed to encode a cytochrome c protein. We isolatedmore »mtoD from a Shewanella oneidensis expression system where the mtoD gene was expressed on a pBAD plasmid vector. Biochemical, biophysical, and crystallographic characterization of the purified MtoD revealed it as an 11 kDa monomeric protein containing a single heme. Sequence and structural alignment indicated that MtoD belonged to the class-1 cytochrome c family and had a similar fold to ferricytochrome c552 family, however the MtoD heme is bis-histidine coordinated and is substantially more exposed than the hemes of other family members. The reduction potential of the MtoD heme at pH 7 was +155 mV vs. Standard Hydrogen Electrode, which is approximately 100 mV lower than that of mitochondrial cytochrome c. Consideration of the properties of MtoD in the context of the potential respiratory partners identified from the genome suggests that MtoD could associate to multiple electron transfer partners as the primary periplasmic electron shuttle.« less

  4. Characterization of MtoD from Sideroxydans lithotrophicus: a cytochrome c electron shuttle used in lithoautotrophic growth

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Beckwith, Christopher R. [Univ. of East Anglia, Norwich (United Kingdom); Edwards, Marcus J. [Univ. of East Anglia, Norwich (United Kingdom); Lawes, Matthew [Univ. of East Anglia, Norwich (United Kingdom); Shi, Liang [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Butt, Julea N. [Univ. of East Anglia, Norwich (United Kingdom); Richardson, David J. [Univ. of East Anglia, Norwich (United Kingdom); Clarke, Thomas A. [Univ. of East Anglia, Norwich (United Kingdom)

    2015-04-28

    The autotrophic Sideroxydans lithotrophicus ES-1 can grow by coupling the oxidation of ferrous iron to the reduction of oxygen. Soluble ferrous iron is oxidized at the surface of the cell by an MtoAB porin-cytochrome complex that functions as an electron conduit through the outer membrane. Electrons are then transported to the cytoplasmic membrane where they are used to generate proton motive force (PMF) (for ATP synthesis) and NADH for autotrophic processes such as carbon fixation. As part of the mtoAB gene cluster, S. lithotrophicus also contains the gene mtoD that is proposed to encode a cytochrome c protein. We isolated mtoD from a Shewanella oneidensis expression system where the mtoD gene was expressed on a pBAD plasmid vector. Biochemical, biophysical, and crystallographic characterization of the purified MtoD revealed it as an 11 kDa monomeric protein containing a single heme. Sequence and structural alignment indicated that MtoD belonged to the class-1 cytochrome c family and had a similar fold to ferricytochrome c552 family, however the MtoD heme is bis-histidine coordinated and is substantially more exposed than the hemes of other family members. The reduction potential of the MtoD heme at pH 7 was +155 mV vs. Standard Hydrogen Electrode, which is approximately 100 mV lower than that of mitochondrial cytochrome c. Consideration of the properties of MtoD in the context of the potential respiratory partners identified from the genome suggests that MtoD could associate to multiple electron transfer partners as the primary periplasmic electron shuttle.

  5. UCL DEPARTMENT OF SPACE & CLIMATE PHYSICS SPACE PLASMA PHYSICS GROUP

    E-Print Network [OSTI]

    UCL DEPARTMENT OF SPACE & CLIMATE PHYSICS SPACE PLASMA PHYSICS GROUP 18th September 2012 STFC Summer School An Introduction to the Structure of the Magnetosphere Prof. Chris Owen Mullard Space 2012 #12;UCL DEPARTMENT OF SPACE & CLIMATE PHYSICS SPACE PLASMA PHYSICS GROUP 18th September 2012 STFC

  6. Quotients of Metric Spaces

    E-Print Network [OSTI]

    Herman, Robert A.

    1968-01-01

    . PRELIMINARIES 1 CHAPTER II . SFACBS IN WHICH SEQUENCES SUFFICE 6 CHAPTER III . QUOTIENTS OF SEPARABLE METRIC SPACES Ik CHAPTER IV. GENERAL QUOTIENT SPACES 25 CHAPTER V. CLOSED QUOTIENT MAPS 35 CHAPTER VI. OPEN QUOTIENT MAPS 50 CHAPTER VII. OPEN AND CLOSED... QUOTIENT MAPS 55 CHAPTER VIII. ANOTHER RESULT 6l BIBLIOGRAPHY 65 CHAPTER I. PRELIMINARIES We begin by stating some basic definitions and theorems. Definition 1 . 1 ; Let f be a function from a topological space X onto a set Y. Then the quotient...

  7. Total Space Heat-

    Gasoline and Diesel Fuel Update (EIA)

    Survey: Energy End-Use Consumption Tables Total Space Heat- ing Cool- ing Venti- lation Water Heat- ing Light- ing Cook- ing Refrig- eration Office Equip- ment Com- puters Other...

  8. Notes on sexuality & space

    E-Print Network [OSTI]

    Jacobson, Samuel Ray

    2013-01-01

    Very little has been written on sexuality in architectural scholarship. Sexuality & Space (Princeton Architectural Press, 1992) contains the proceedings of an eponymous 1990 conference at Princeton University, and was both ...

  9. Saving Space in China

    E-Print Network [OSTI]

    Hacker, Randi

    2013-09-09

    Broadcast Transcript: The Chinese are geniuses at utilizing every inch of space. In a country that is historically overcrowded, this skill is important for survival. Chinese vegetable gardens are miracles of permaculture layout: small plants nestle...

  10. Commutators on Banach Spaces 

    E-Print Network [OSTI]

    Dosev, Detelin

    2010-10-12

    . In particular, we will focus our attention to the spaces $\\lambda I and $\\linf$. The main results are that the commutators on $\\ell_1$ are the operators not of the form $\\lambda I + K$ with $\\lambda\

  11. Observation of multi-scale oscillation of laminar lifted flames with low-frequency AC electric fields

    SciTech Connect (OSTI)

    Ryu, S.K.; Kim, Y.K.; Kim, M.K.; Won, S.H. [School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742 (Korea); Chung, S.H. [Clean Combustion Research Center, King Abdullah University of Science and Technology, Thuwal (Saudi Arabia)

    2010-01-15

    The oscillation behavior of laminar lifted flames under the influence of low-frequency AC has been investigated experimentally in coflow jets. Various oscillation modes were existed depending on jet velocity and the voltage and frequency of AC, especially when the AC frequency was typically smaller than 30 Hz. Three different oscillation modes were observed: (1) large-scale oscillation with the oscillation frequency of about 0.1 Hz, which was independent of the applied AC frequency, (2) small-scale oscillation synchronized to the applied AC frequency, and (3) doubly-periodic oscillation with small-scale oscillation embedded in large-scale oscillation. As the AC frequency decreased from 30 Hz, the oscillation modes were in the order of the large-scale oscillation, doubly-periodic oscillation, and small-scale oscillation. The onset of the oscillation for the AC frequency smaller than 30 Hz was in close agreement with the delay time scale for the ionic wind effect to occur, that is, the collision response time. Frequency-doubling behavior for the small-scale oscillation has also been observed. Possible mechanisms for the large-scale oscillation and the frequency-doubling behavior have been discussed, although the detailed understanding of the underlying mechanisms will be a future study. (author)

  12. Effects of alpha-zirconium phosphate on thermal degradation and flame retardancy of transparent intumescent fire protective coating

    SciTech Connect (OSTI)

    Xing, Weiyi [State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzai Road, Hefei, Anhui 230026 (China); Zhang, Ping [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, 59 Qinglong Road, Mianyang 621010 (China); Song, Lei; Wang, Xin [State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzai Road, Hefei, Anhui 230026 (China); Hu, Yuan, E-mail: yuanhu@ustc.edu.cn [State Key Laboratory of Fire Science, University of Science and Technology of China, 96 Jinzai Road, Hefei, Anhui 230026 (China)

    2014-01-01

    Graphical abstract: - Highlights: • A transparent intumescent fire protective coating was obtained by UV-cured technology. • OZrP could enhance the thermal stability and anti-oxidation of the coating. • OZrP could reduce the combustion properties of the coatings. - Abstract: Organophilic alpha-zirconium phosphate (OZrP) was used to improve the thermal and fire retardant behaviors of the phenyl di(acryloyloxyethyl)phosphate (PDHA)-triglycidyl isocyanurate acrylate (TGICA)-2-phenoxyethyl acrylate (PHEA) (PDHA-TGICA-PHEA) coating. The morphology of nanocomposite coating was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The effect of OZrP on the flame retardancy, thermal stability, fireproofing time and char formation of the coatings was investigated by microscale combustion calorimeter (MCC), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), laser Raman spectroscopy (LRS) and scanning electric microscope (SEM). The results showed that by adding OZrP, the peak heat release rate and total heat of combustion were significantly reduced. The highest improvement was achieved with 0.5 wt% OZrP. XPS analysis indicated that the performance of anti-oxidation of the coating was improved with the addition of OZrP, and SEM images showed that a good synergistic effect was obtained through a ceramic-like layer produced by OZrP covered on the surface of char.

  13. Improvement of load-following capacity based on the flame radiation intensity signal in a power plant

    SciTech Connect (OSTI)

    Fei Wang; Qunxing Huang; Dong Liu; Jianhua Yan; Kefa Cen [Zhejiang University, Hangzhou (China). State Key Laboratory of Clean Energy Utilization

    2008-05-15

    The capability to perform fast load changes has been an important issue due to the increasing commercialization of the power market. In the traditional boiler control system, the feedback signals come from the variations of the steam pressure and the steam flow, which leads to a large time delay. Therefore, a new method for the boiler control system based on radiation intensity for improving the load-following capacity of a coal-fired power plant has been developed in this paper. The system is implemented by adding the radiation intensity of the flame to the existing boiler control system as a complement. The radiation intensity obtained by the sensor can directly reflect the input heat in the boiler, with a faster response and higher sensitivity. Field tests on a 300 MW coal-fired power plant reveal that the improved boiler control system increases the load-following capacity. At the same time, the steam pressure variations are smaller as compared with those of the existing control system. 14 refs., 19 figs., 1 tab.

  14. CERN celebrated the first year in space for the Alpha Magnetic Spectrometer (AMS) with a visit from the crew of the shuttle mission, STS-134, who successfully delivered AMS to the International Space Station (ISS) last year.

    E-Print Network [OSTI]

    Laurent Egli

    2012-01-01

    During the celebrations at CERN, the astronauts unveiled a commemorative plaque on the lawn outside the POCC to mark the occasion and later gave a public lecture at CERN. Picture 28 : STS-134 astronauts (left to right) Andrew Feustel, Gregory Chamitoff, Gregory Johnson, Michael Fincke and Mark Kelly in the AMS Payload Operations Centre at CERN.

  15. National Aeronautics and Space Administration

    E-Print Network [OSTI]

    Rathbun, Julie A.

    ,,/ NASA National Aeronautics and Space Administration Lyndon B. Johnson Space Center Houston by the National Aeronautics and Space Administration ii Hosted by the National Academy of Sclences for library, abstract service, educational, or research purposes; however, republication of any paper

  16. EARTH OBSERVATIONS FROM SPACE Spring Term 2005

    E-Print Network [OSTI]

    Strong, Kimberly

    , after which the essay will not be accepted. Some selected topics are listed below, and have been chosen TOPICS: (1) PMR ­ Pressure Modulator Radiometer (Nimbus 6, 1975) · measured atmospheric temperature · used infrared gas correlation spectroscopy (2) SSBUV ­ Shuttle Solar Backscatter Ultraviolet Instrument

  17. China's Space Robotic Arms Programs

    E-Print Network [OSTI]

    POLLPETER, Kevin

    2013-01-01

    2013 China’s Space Robotic Arm Programs Kevin POLLPETERdebris observation and space robotic arm technologies. Thelikely equipped with a robotic arm, grappling the target

  18. Debris and Future Space Activities

    E-Print Network [OSTI]

    California at Santa Cruz, University of

    Debris and Future Space Activities Prof. Joel R. Primack Physics Department University would be endangered. Every person who cares about the human future in space should also realize

  19. Shuttle Parking MIDDLEMIDDLE

    E-Print Network [OSTI]

    &2­29 Boiler House­5 Boiler House 2­77 Bray Hall­48 Bryckwyck­61 2144 Burdett Avenue­51 Burdett Residence Hall NUMERICAL 1. Pittsburgh Building 2. West Hall 3. Carnegie Building 4. Walker Laboratory 5. Boiler House 6

  20. TAKU SHUTTLE YUKON DRIVE

    E-Print Network [OSTI]

    Ickert-Bond, Steffi

    Duckering St. Mark's Chapman Patty Center Lathrop Switchgear Energy Technology Test Modules Nerland Mc