Sample records for flame stabilization virtually

  1. Laser controlled flame stabilization

    DOE Patents [OSTI]

    Early, James W. (Los Alamos, NM); Thomas, Matthew E. (Huntsville, AL)

    2001-01-01T23:59:59.000Z

    A method and apparatus is provided for initiating and stabilizing fuel combustion in applications such as gas turbine electrical power generating engines and jet turbine engines where it is desired to burn lean fuel/air mixtures which produce lower amounts of NO.sub.x. A laser induced spark is propagated at a distance from the fuel nozzle with the laser ignitor being remotely located from the high temperature environment of the combustion chamber. A laser initiating spark generated by focusing high peak power laser light to a sufficiently tight laser spot within the fuel to cause the ionization of air and fuel into a plasma is unobtrusive to the flow dynamics of the combustion chamber of a fuel injector, thereby facilitating whatever advantage can be taken of flow dynamics in the design of the fuel injector.

  2. [Mechanism and enhancement of flame stabilization]. [Annual report, 1993--1994

    SciTech Connect (OSTI)

    Not Available

    1993-11-01T23:59:59.000Z

    During this period, the following projects were completed: structural invariance of purely strained planar premixed flames, thermophoretic effects on seeding particles in LDV measurements, analysis of geometry of Bunsen flames, flame propagation in periodic flow fields, adiabatic flame stabilization, and chain-thermal theory of flame extinction.

  3. 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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn12electron 9 5 -of EnergyLeadership Leadership|Lean Flame

  4. Blowoff characteristics of bluff-body stabilized conical premixed flames under upstream velocity modulation

    SciTech Connect (OSTI)

    Chaparro, Andres A.; Cetegen, Baki M. [Mechanical Engineering Department, University of Connecticut, Storrs, CT 06269-3139 (United States)

    2006-01-01T23:59:59.000Z

    This article presents experimental findings on the blowoff characteristics of conical premixed flames anchored at their apex by three different flame holders (rod, disk, and cone) in the presence of upstream velocity oscillations. Experiments were performed with propane-air mixtures at mixture velocities approaching the flame holder of 5, 10, and 15 m/s. The flow speed was modulated sinusoidally at frequencies up to 400 Hz with a constant-velocity modulation amplitude of u{sub rms}/U{sub m}=0.08 upstream of the flame holder. It was found that the blowoff equivalence ratio exhibits a dependence on the flow modulation frequency. Specifically, at low approach velocities (5 m/s), the effect of upstream flow modulation is to improve flame stability as evidenced by lower flame blowoff equivalence ratios for all three types of flame holders considered. At higher approach velocities (10 and 15 m/s), the disk- and cone-shaped flame holders exhibit less stability with increasing excitation frequency. The rod-shaped flame holder behavior is different at these higher velocities in that the flow modulation still provides enhanced flame stability. The flame stability results are supplemented with a detailed analysis of the flow field in the flame stabilization zone obtained by particle image velocimetry.

  5. Stabilization of turbulent lifted jet flames assisted by pulsed high voltage discharge

    SciTech Connect (OSTI)

    Criner, K.; Cessou, A.; Louiche, J.; Vervisch, P. [CORIA UMR 6614 CNRS-Universite et INSA de Rouen, University of Rouen, 76801 Saint Etienne du Rouvray (France)

    2006-01-01T23:59:59.000Z

    To reduce fuel consumption or the pollutant emissions of combustion (furnaces, aircraft engines, turbo-reactors, etc.), attempts are made to obtain lean mixture combustion regimes. These lead to poor stability of the flame. Thus, it is particularly interesting to find new systems providing more flexibility in aiding flame stabilization than the usual processes (bluff-body, stabilizer, quarl, swirl, etc.). The objective is to enlarge the stability domain of flames while offering flexibility at a low energy cost. Evidence is presented that the stabilization of a turbulent partially premixed flame of more than 10 kW can be enhanced by pulsed high-voltage discharges with power consumption less than 0.1% of the power of the flame. The originality of this work is to demonstrate that very effective stabilization of turbulent flames is obtained when high-voltage pulses with very short rise times are used (a decrease by 300% in terms of liftoff height for a given exit jet velocity can be reached) and to provide measurements of minimum liftoff height obtained with discharge over a large range of the stability domain of the lifted jet flame.

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

    E-Print Network [OSTI]

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

    2003-05-02T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Kedia, Kushal Sharad

    2010-01-01T23:59:59.000Z

    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 ...

  8. Flame Stability Analysis in an Ultra Compact Combustor Using Large-Eddy Simulation

    E-Print Network [OSTI]

    Raman, Venkat

    Flame Stability Analysis in an Ultra Compact Combustor Using Large-Eddy Simulation C. Lietz , C Base, Ohio 45433 Large eddy simulation (LES) of an experimental ultra-compact combustor (UCC as a conven- tional combustor path. In order to reduce the penalty due to increased weight of these burners

  9. Transfer function characteristics of bluff-body stabilized, conical V-shaped premixed turbulent propane-air flames

    SciTech Connect (OSTI)

    Chaparro, Andres; Landry, Eric; Cetegen, Baki M. [Mechanical Engineering Department, University of Connecticut, 191 Auditorium Road, Storrs, CT 06269-3139 (United States)

    2006-04-15T23:59:59.000Z

    The response of bluff-body stabilized conical V-shaped premixed flames to periodic upstream velocity oscillations was characterized as a function of oscillation frequency, mean flow velocity, and equivalence ratio. The flame heat release response to the imposed velocity oscillations was determined from the CH* chemiluminescence captured by two photomultiplier (PMT) detectors at a wavelength of 430 nm. One of the PMTs viewed flame radiation in a 10-mm horizontal slice, 50 mm above the bluff-body. The second PMT observed the overall flame radiation. The flame transfer function characteristics were determined from the spectral analysis of the velocity and PMT signals. It was found that the flame heat release amplitude response is confined to low-frequency excitation below a Strouhal number of 4. The phase relationship of the transfer function for these turbulent flames was evaluated using the signal from the spatially masked PMT. The transfer function estimate based on these data exhibits second-order characteristics with a phase lag between the velocity and heat release signals. The localized heat-release response contains frequencies that are multiples of the excitation frequency, suggesting splitting and tilting of flame structures as well as some nonlinear effects. Increase of flame equivalence ratio from lean toward stoichiometric resulted in slight amplification of the high-frequency response. (author)

  10. Blowoff characteristics of bluff-body stabilized conical premixed flames with upstream spatial mixture gradients and velocity oscillations

    SciTech Connect (OSTI)

    Chaudhuri, Swetaprovo; Cetegen, Baki M. [Mechanical Engineering Department, University of Connecticut, Storrs, CT 06269-3139 (United States)

    2008-06-15T23:59:59.000Z

    This experimental study concerns determination of blowoff equivalence ratios for lean premixed conical flames for different mixture approach velocities ranging from 5 to 16 m/s in the presence of spatial mixture gradients and upstream velocity modulation. Conical flames were anchored on a disk-shaped bluff body that was attached to a central rod in the burner nozzle. A combustible propane-air mixture flowed through a converging axisymmetric nozzle with a concentric insert, allowing radial mixture variation by tailoring the composition in the inner and outer parts of the nozzle. The radial mixture profiles were characterized near the location of the flame holder by laser Rayleigh light scattering. Additionally, a loudspeaker at the nozzle base allowed introduction of periodic velocity oscillations with an amplitude of 9% of the mean flow velocity up to a frequency of 350 Hz. The flame blowoff equivalence ratio was experimentally determined by continuously lowering the fuel flow rates and determining the flame detachment point from the flame holder. Flame detachment was detected by a rapid reduction of CH* emission from the flame base imaged by a photomultiplier detector. It was found that the flame blowoff is preceded by progressive narrowing of the flame cone for the case of higher inner jet equivalence ratios. In this case, the fuel-lean outer flow cannot sustain combustion, and clearly this is not a good way of operating a combustor. Nevertheless, the overall blowoff equivalence ratio is reduced by inner stream fuel enrichment. A possible explanation for this behavior is given based on the radial extent of the variable-equivalence-ratio mixture burning near the flame stabilization region. Fuel enrichment in the outer flow was found to have no effect on blowoff as compared to the case of uniform mixture. The results were similar for the whole range of mean flow velocities and upstream excitation frequencies. (author)

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

    E-Print Network [OSTI]

    Lowry, William Baugh

    2012-02-14T23:59:59.000Z

    . Hydrocarbon blends of methane, ethane, and propane make up a large portion of natural gas and it has been shown that dimethyl ether can be used as a supplement or in its pure form for gas turbine combustion. Because of this, a fundamental understanding... include the flame speeds for binary blends of methane, ethane, propane, and dimethyl ether performed at elevated pressures, up to 10-atm initial pressure, using a spherically expanding flame in a constant-volume vessel. Also included in this thesis is a...

  12. Flame transfer function saturation mechanisms in a swirl-stabilized combustor

    E-Print Network [OSTI]

    Lieuwen, Timothy C.

    oscillations using phase-locked, two-dimensional OH PLIF imaging. It focuses upon two repre- sentative An understanding of the amplitude dependence of the flame response to harmonic acoustic excitation is required during the phase of the cycle of peak instantaneous axial velocity. This causes the flame attachment

  13. 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

  14. On the structure, propagation, and stabilization of laminar premixed flames. Final report

    SciTech Connect (OSTI)

    Law, Chung K.

    1999-07-01T23:59:59.000Z

    The primary objective of the funded program was to qualitatively understand and quantitatively determine the structure and dynamics of laminar premixed flames. The investigation was conducted using laser-based experimentation, computational simulation with detailed chemistry and transport, and activation energy asymptotic analysis. Highlights of accomplishments were discussed in the annual reports submitted to the program monitor for this project. Details are reported in the thirty journal publications cited in the journal article list which is the major component of this final report.

  15. Dynamics and structure of stretched flames

    SciTech Connect (OSTI)

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

    1993-12-01T23:59:59.000Z

    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.

  16. Carrier mobilities and process stability of strained Si n-and p-MOSFETs on SiGe virtual substrates

    E-Print Network [OSTI]

    Carrier mobilities and process stability of strained Si n- and p-MOSFETs on SiGe virtual substrates. INTRODUCTION Since the advent of the relaxed graded buffer technique in 1991,1 SiGe alloys have been a proven path to increasing the functionality of the silicon microelectronics platform. SiGe virtual substrates

  17. Investigating the Flame Microstructure in Type Ia Supernovae

    E-Print Network [OSTI]

    Roepke, F K; Niemeyer, J C

    2002-01-01T23:59:59.000Z

    We present a numerical model to study the behavior of thermonuclear flames in the discontinuity approximation. This model is applied to investigate the Landau-Darrieus instability under conditions found in Type Ia supernova explosions of Chandrasekhar mass white dwarfs. This is a first step to explore the flame microstructure in these events. The model reproduces Landau's linearized stability analysis in early stages of the flame evolution and the stabilization in a cellular flame structure in the nonlinear stage.

  18. Investigating the Flame Microstructure in Type Ia Supernovae

    E-Print Network [OSTI]

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

    2002-04-02T23:59:59.000Z

    We present a numerical model to study the behavior of thermonuclear flames in the discontinuity approximation. This model is applied to investigate the Landau-Darrieus instability under conditions found in Type Ia supernova explosions of Chandrasekhar mass white dwarfs. This is a first step to explore the flame microstructure in these events. The model reproduces Landau's linearized stability analysis in early stages of the flame evolution and the stabilization in a cellular flame structure in the nonlinear stage.

  19. 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

    2014-06-25T23:59:59.000Z

    of around 100,000 polyhedral cells and is refined in the fuel jet and flame regions, thereby leading to 100-200 LES cells within one CMC cell there. This CMC mesh refinement is expected to be useful here because fine local CMC resolution can better... . In CMC, h=0 corresponds to air and h=1 to pure fuel, both at 298 K. The fully burning steady solutions with 10 50 sN ?? from a 0D-CMC calculation are used to initialize all the CMC cells. Inert mixing solutions are injected in the air and fuel inlets...

  20. 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)

    2010-06-15T23:59:59.000Z

    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)

  1. Active control for turbulent premixed flame simulations

    SciTech Connect (OSTI)

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

    2004-03-26T23:59:59.000Z

    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.

  2. Using Ligand-Based Virtual Screening to Allosterically Stabilize the Activated State of a

    E-Print Network [OSTI]

    Marshall, Garland R.

    virtually screening the Maybridge library, whereas no hits resulted with the National Cancer Institute-protein coupled receptors play an essential role in many biological processes. Despite an increase in the number the possible discovery of novel scaffolds. Maybridge Hitfinder and National Cancer Institute diversity

  3. Flame front configuration of turbulent premixed flames

    SciTech Connect (OSTI)

    Furukawa, Junichi [Tokyo Metropolitan Technical Coll. (Japan). Dept. of Mechanical Engineering] [Tokyo Metropolitan Technical Coll. (Japan). Dept. of Mechanical Engineering; Maruta, Kaoru [Tohoku Univ., Sendai (Japan). Inst. of Fluid Science] [Tohoku Univ., Sendai (Japan). Inst. of Fluid Science; Hirano, Toshisuke [Univ. of Tokyo (Japan). Dept. of Chemical System Engineering] [Univ. of Tokyo (Japan). Dept. of Chemical System Engineering

    1998-02-01T23:59:59.000Z

    The present study is performed to explore dependence of the wrinkle scale of propane-air turbulent premixed flames on the characteristics of turbulence in the nonreacting flow, burner size, and mixture ratio. The wrinkle scales are examined and expressed in the frequency distribution of the radii of flame front curvatures. The average wrinkle scale depends not only on the characteristics of turbulence in the nonreacting flow but also on burner diameter and mixture ratio. The average wrinkle scale of a lean propane-air flame is larger than those of the near stoichiometric and rich flames. The smallest wrinkle scale of turbulent premixed flame is in the range of 0.75--1.0 mm, which is much larger than the Kolmogorov scale of turbulence in the nonreacting flow.

  4. Premixed turbulent flame front structure investigation by Rayleigh scattering in the thin

    E-Print Network [OSTI]

    Gülder, Ömer L.

    in propane flames. The probability density function of curvature showed a Gaussian-like distribution at all­air and propane­air stabilized on a bunsen type burner were studied using planar Rayleigh scattering and particle flames, and from 0.7 to stoichiometric for propane flames. The non-dimensional turbulence rms velocity, u

  5. 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

  6. NO concentration imaging in turbulent nonpremixed flames

    SciTech Connect (OSTI)

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

    1993-12-01T23:59:59.000Z

    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.

  7. On the Flame Height Definition for Upward Flame Spread 

    E-Print Network [OSTI]

    Consalvi, Jean L; Pizzo, Yannick; Porterie, Bernard; Torero, Jose L

    2007-01-01T23:59:59.000Z

    Flame height is defined by the experimentalists as the average position of the luminous flame and, consequently is not directly linked with a quantitative value of a physical parameter. To determine flame heights from ...

  8. 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

  9. Approaches to modeling thermonuclear flames

    E-Print Network [OSTI]

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

    Turbulence-flame interactions of thermonuclear fusion flames occurring in Type Ia Supernovae were studied by means of incompressible DNS 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

  10. The effect of fuel composition on flame dynamics

    SciTech Connect (OSTI)

    Hendricks, Adam G.; Vandsburger, Uri [Department of Mechanical Engineering - 0238, Virginia Tech, Blacksburg, VA 24061 (United States)

    2007-10-15T23:59:59.000Z

    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)

  11. The Cellular Burning Regime in Type Ia Supernova Explosions - I. Flame Propagation into Quiescent Fuel

    E-Print Network [OSTI]

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

    2003-12-03T23:59:59.000Z

    We present a numerical investigation of the cellular burning regime in Type Ia supernova explosions. This regime holds at small scales (i.e. below the Gibson scale), which are unresolved in large-scale Type Ia supernova simulations. The fundamental effects that dominate the flame evolution here are the Landau-Darrieus instability and its nonlinear stabilization, leading to a stabilization of the flame in a cellular shape. The flame propagation into quiescent fuel is investigated addressing the dependence of the simulation results on the specific parameters of the numerical setup. Furthermore, we investigate the flame stability at a range of fuel densities. This is directly connected to the questions of active turbulent combustion (a mechanism of flame destabilization and subsequent self-turbulization) and a deflagration-to-detonation transition of the flame. In our simulations we find no substantial destabilization of the flame when propagating into quiescent fuels of densities down to ~10^7 g/cm^3, corroborating fundamental assumptions of large-scale SN Ia explosion models. For these models, however, we suggest an increased lower cutoff for the flame propagation velocity to take the cellular burning regime into account.

  12. Combustion and Flame 139 (2004) 90105 www.elsevier.com/locate/jnlabr/cnf

    E-Print Network [OSTI]

    Aggarwal, Suresh K.

    2004-01-01T23:59:59.000Z

    . Barlow and Carter [1] investigated experimentally the effects of temperature and mixture fraction on NOx formed experimental and numerical investigations on NOx emissions from turbulent propane diffusion flames stabilized lean premixed methane­air

  13. Numerical and experimental investigation of vortical flow-flame interaction

    SciTech Connect (OSTI)

    Najm, H.N.; Schefer, R.W.; Milne, R.B.; Mueller, C.J. [Sandia National Labs., Livermore, CA (United States); Devine, K.D.; Kempka, S.N. [Sandia National Labs., Albuquerque, NM (United States)

    1998-02-01T23:59:59.000Z

    A massively parallel coupled Eulerian-Lagrangian low Mach number reacting flow code is developed and used to study the structure and dynamics of a forced planar buoyant jet flame in two dimensions. The numerical construction uses a finite difference scheme with adaptive mesh refinement for solving the scalar conservation equations, and the vortex method for the momentum equations, with the necessary coupling terms. The numerical model construction is presented, along with computational issues regarding the parallel implementation. An experimental acoustically forced planar jet burner apparatus is also developed and used to study the velocity and scalar fields in this flow, and to provide useful data for validation of the computed jet. Burner design and laser diagnostic details are discussed, along with the measured laboratory jet flame dynamics. The computed reacting jet flow is also presented, with focus on both large-scale outer buoyant structures and the lifted flame stabilization dynamics. A triple flame structure is observed at the flame base in the computed flow, as is theoretically expected, but was not observable with present diagnostic techniques in the laboratory flame. Computed and experimental results are compared, along with implications for model improvements.

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

    E-Print Network [OSTI]

    Kulatilaka, Waruna Dasal

    2002-01-01T23:59:59.000Z

    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...

  15. Flame propagation enhancement by plasma excitation of oxygen. Part I: Effects of O{sub 3}

    SciTech Connect (OSTI)

    Ombrello, Timothy; Won, Sang Hee; Ju, Yiguang [Department of Mechanical and Aerospace Engineering, Engineering Quadrangle, Olden Street, Princeton, NJ 08544 (United States); Williams, Skip [Air Force Research Laboratory, Propulsion Directorate, 1950 Fifth Street, Wright-Patterson AFB, OH 45433 (United States)

    2010-10-15T23:59:59.000Z

    The thermal and kinetic effects of O{sub 3} on flame propagation were investigated experimentally and numerically by using C{sub 3}H{sub 8}/O{sub 2}/N{sub 2} laminar lifted flames. Ozone produced by a dielectric barrier plasma discharge was isolated and measured quantitatively by using absorption spectroscopy. Significant kinetic enhancement by O{sub 3} was observed by comparing flame stabilization locations with and without O{sub 3} production. Experiments at atmospheric pressures showed an 8% enhancement in the flame propagation speed for 1260 ppm of O{sub 3} addition to the O{sub 2}/N{sub 2} oxidizer. Numerical simulations showed that the O{sub 3} decomposition and reaction with H early in the pre-heat zone of the flame produced O and OH, respectively, from which the O reacted rapidly with C{sub 3}H{sub 8} and produced additional OH. The subsequent reaction of OH with the fuel and fuel fragments, such as CH{sub 2}O, provided chemical heat release at lower temperatures to enhance the flame propagation speed. It was shown that the kinetic effect on flame propagation enhancement by O{sub 3} reaching the pre-heat zone of the flame for early oxidation of fuel was much greater than that by the thermal effect from the energy contained within O{sub 3}. For non-premixed laminar lifted flames, the kinetic enhancement by O{sub 3} also induced changes to the hydrodynamics at the flame front which provided additional enhancement of the flame propagation speed. The present results will have a direct impact on the development of detailed plasma-flame kinetic mechanisms and provided a foundation for the study of combustion enhancement by O{sub 2}(a{sup 1}{delta}{sub g}) in part II of this investigation. (author)

  16. Virtual Exhibits

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

    Virtual Exhibits Inside the Museum Exhibitions Norris Bradbury Museum Lobby Defense Gallery Research Gallery History Gallery TechLab Virtual Exhibits invisible utility element...

  17. The Cellular Burning Regime in Type Ia Supernova Explosions - II. Flame Propagation into Vortical Fuel

    E-Print Network [OSTI]

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

    2003-12-08T23:59:59.000Z

    We investigate the interaction of thermonuclear flames in Type Ia supernova explosions with vortical flows by means of numerical simulations. In our study, we focus on small scales, where the flame propagation is no longer dominated by the turbulent cascade originating from large-scale effects. Here, the flame propagation proceeds in the cellular burning regime, resulting from a balance between the Landau-Darrieus instability and its nonlinear stabilization. The interaction of a cellularly stabilized flame front with a vortical fuel flow is explored applying a variety of fuel densities and strengths of the velocity fluctuations. We find that the vortical flow can break up the cellular flame structure if it is sufficiently strong. In this case the flame structure adapts to the imprinted flow field. The transition from the cellularly stabilized front to the flame structure dominated by vortices of the flow proceeds in a smooth way. The implications of the results of our simulations for Type Ia Supernova explosion models are discussed.

  18. advanced flame quality: Topics by E-print Network

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

    to modeling thermonuclear flames CiteSeer Summary: Turbulence-flame interactions of thermonuclear fusion flames occurring in Type Ia Supernovae were studied by means of...

  19. aircraft cargo flame: Topics by E-print Network

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

    to modeling thermonuclear flames CiteSeer Summary: Turbulence-flame interactions of thermonuclear fusion flames occurring in Type Ia Supernovae were studied by means of...

  20. aerosol flame deposition: Topics by E-print Network

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

    to modeling thermonuclear flames CiteSeer Summary: Turbulence-flame interactions of thermonuclear fusion flames occurring in Type Ia Supernovae were studied by means of...

  1. On the critical flame radius and minimum ignition energy for spherical flame initiation

    SciTech Connect (OSTI)

    Chen, Zheng; Burke, M. P.; Ju, Yiguang

    2011-01-01T23:59:59.000Z

    Spherical flame initiation from an ignition kernel is studied theoretically and numerically using different fuel/oxygen/helium/argon mixtures (fuel: hydrogen, methane, and propane). The emphasis is placed on investigating the critical flame radius controlling spherical flame initiation and its correlation with the minimum ignition energy. It is found that the critical flame radius is different from the flame thickness and the flame ball radius and that their relationship depends strongly on the Lewis number. Three different flame regimes in terms of the Lewis number are observed and a new criterion for the critical flame radius is introduced. For mixtures with Lewis number larger than a critical Lewis number above unity, the critical flame radius is smaller than the flame ball radius but larger than the flame thickness. As a result, the minimum ignition energy can be substantially over-predicted (under-predicted) based on the flame ball radius (the flame thickness). The results also show that the minimum ignition energy for successful spherical flame initiation is proportional to the cube of the critical flame radius. Furthermore, preferential diffusion of heat and mass (i.e. the Lewis number effect) is found to play an important role in both spherical flame initiation and flame kernel evolution after ignition. It is shown that the critical flame radius and the minimum ignition energy increase significantly with the Lewis number. Therefore, for transportation fuels with large Lewis numbers, blending of small molecule fuels or thermal and catalytic cracking will significantly reduce the minimum ignition energy.

  2. 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)

    2010-08-15T23:59:59.000Z

    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)

  3. Flame Spectral Analysis for Boiler Control 

    E-Print Network [OSTI]

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

    1987-01-01T23:59:59.000Z

    FLAME SPECTRAL ANALYSIS FOR BOILER CONTROL CHRISTOPHER I. METCALFE WILLIAM E. COLE SUSHIL K. BATRA Tecogen, Inc. ( A Subsidiary of Thermo Electron Corporation) Waltham, Massachusetts ABSTRACT SPECTRAL FLAME ANALYSIS FOR BURNER CONTROL During...

  4. Transient Supersonic Methane-Air Flames

    E-Print Network [OSTI]

    Richards, John L.

    2012-07-16T23:59:59.000Z

    The purpose of this study was to investigate the thermochemical properties of a transient supersonic flame. Creation of the transient flame was controlled by pulsing air in 200 millisecond intervals into a combustor filled with flowing methane...

  5. Characterization of acoustically forced swirl flame dynamics

    E-Print Network [OSTI]

    Lieuwen, Timothy C.

    of the flame to acoustic excitation is required. This study presents an analysis of phase-locked OH PLIF images of acoustically excited swirl flames, to identify the key controlling physical processes and qualitatively discuss, and whose relative significance depends upon forcing frequency, amplitude of excitation, and flame

  6. 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

  7. Electric-field-induced flame speed modification

    SciTech Connect (OSTI)

    Marcum, S.D. [Department of Physics, Miami University, Oxford, OH 45056 (United States); Ganguly, B.N. [Air Force Research Laboratory, Wright-Patterson AFB, OH 45433 (United States)

    2005-10-01T23:59:59.000Z

    The effects of pulsed and continuous DC electric fields on the reaction zones of premixed propane-air flames have been investigated using several types of experimental measurements. All observed effects on the flame are dependent on the applied voltage polarity, indicating that negatively charged flame species do not play a role in the perturbation of the reaction zone. Experiments designed to characterize the electric-field-induced modifications of the shape and size of the inner cone, and the concomitant changes in the temperature profiles of flames with equivalence ratios between 0.8 and 1.7, are also reported. High-speed two-dimensional imaging of the flame response to a pulsed DC voltage shows that the unperturbed conical flame front (laminar flow) is driven into a wrinkled laminar flamelet (cellular) geometry on a time scale of the order of 5 ms. Temperature distributions derived from thin filament pyrometry (TFP) measurements in flames perturbed by continuous DC fields show similar large changes in the reaction zone geometry, with no change in maximum flame temperature. All measurements are consistent with the observed flame perturbations being a fluid mechanical response to the applied field brought about by forcing positive flame ions counter to the flow. The resulting electric pressure decreases Lewis numbers of the ionic species and drives the effective flame Lewis number below unity. The observed increases in flame speed and the flame fronts trend toward turbulence can be described in terms of the flame front wrinkling and concomitant increase in reaction sheet area. This effect is a potentially attractive means of controlling flame fluid mechanical characteristics. The observed effects require minimal input electrical power (<1 W for a 1 kW burner) due to the much better electric field coupling achieved in the present experiments compared to the previous studies.

  8. 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)

    2010-08-24T23:59:59.000Z

    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.

  9. On the Stability of Thermonuclear Burning Fronts in Type Ia Supernovae

    E-Print Network [OSTI]

    F. K. Roepke; W. Hillebrandt

    2004-04-26T23:59:59.000Z

    The propagation of cellularly stabilized thermonuclear flames is investigated by means of numerical simulations. In Type Ia supernova explosions the corresponding burning regime establishes at scales below the Gibson length. The cellular flame stabilization - which is a result of an interplay between the Landau-Darrieus instability and a nonlinear stabilization mechanism - is studied for the case of propagation into quiescent fuel as well as interaction with vortical fuel flows. Our simulations indicate that in thermonuclear supernova explosions stable cellular flames develop around the Gibson scale and that deflagration-to-detonation transition is unlikely to be triggered from flame evolution effects here.

  10. 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. [School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-744 (Korea)

    2009-02-15T23:59:59.000Z

    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)

  11. Soot formation in laminar premixed ethylene/air flames at atmospheric pressure

    SciTech Connect (OSTI)

    Xu, F.; Sunderland, P.B.; Faeth, G.M. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Aerospace Engineering] [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Aerospace Engineering

    1997-03-01T23:59:59.000Z

    Soot formation was studied within laminar premixed ethylene/air flames (C/O ratios of 0.78--0.98) stabilized on a flat-flame burner operating at atmospheric pressure. Measurements included soot volume fractions by both laser extinction and gravimetric methods, temperatures by multiline emission, soot structure by thermophoretic sampling and transmission electric microscopy, major gas species concentrations by sampling and gas chromatography, concentrations of condensable hydrocarbons by gravimetric sampling, and velocities by laser velocimetry. These data were used to find soot surface growth rates and primary soot particle nucleation rates along the axes of the flames. Present measurements of soot surface growth rates were correlated successfully by predictions based on typical hydrogen-abstraction/carbon-addition (HACA) mechanisms of Frenklach and co-workers and Colket and Hall. These results suggest that reduced soot surface growth rates with increasing residence time seen in the present and other similar flames were mainly caused by reduced rates of surface activation due to reduced H atom concentrations as temperatures decrease as a result of radiative heat losses. Primary soot particle nucleation rates exhibited variations with temperature and acetylene concentrations that were similar to recent observations for diffusion flames; however, nucleation rates in the premixed flames were significantly lower than in the diffusion flames for reasons that still must be explained. Finally, predictions of yields of major gas species based on mechanisms from both Frenklach and co-workers and Leung and Lindstedt were in good agreement with present measurements and suggest that H atom concentrations (relevant to HACA mechanisms) approximate estimates based on local thermodynamic equilibrium in the present flames.

  12. Effect of Hydrogen Addition on the Flammability Limit of Stretched Methane/Air Premixed Flames

    E-Print Network [OSTI]

    Im, Hong G.

    ], thereby enabling stable combustion at lean mixture conditions. In the case of natural gas engines, enriching the fuel with hydrogen has the proven benefits of improving the combustion stability and reducingEffect of Hydrogen Addition on the Flammability Limit of Stretched Methane/Air Premixed Flames

  13. 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.

    2014-01-01T23:59:59.000Z

    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...

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

    SciTech Connect (OSTI)

    Persson, Helena; Andersson, Oeivind; Egnell, Rolf [Lund University (Sweden). Dept. of Energy Sciences

    2011-01-15T23:59:59.000Z

    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)

  15. 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...

  16. Effect of Nitrogen Additives on Flame Retardant Action of Tributyl...

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

    Nitrogen Additives on Flame Retardant Action of Tributyl Phosphate: Phosphorus – Nitrogen Synergism. Effect of Nitrogen Additives on Flame Retardant Action of Tributyl...

  17. Flame acceleration studies in the MINIFLAME facility

    SciTech Connect (OSTI)

    Tieszen, S.R.; Sherman, M.P.; Benedick, W.B.

    1989-07-01T23:59:59.000Z

    Flame acceleration and deflagration-to-detonation transition (DDT) studies have been conducted in a 19.4-cm high, 14.5-cm wide, and 2. 242-m long channel (MINIFLAME) that is a 1:12.6 scale model of the 136-m{sup 3} FLAME facility. Tests were conducted with two levels of hydrogen concentration -- 20% and 30%, with and without obstacles in the channel, and with three levels of transverse top venting -- 0%, 13%, and 50%. The flame acceleration results in MINIFLAME are qualitatively similar to those in FLAME; however, the small-scale results are more benign quantitatively. The results show that insufficient venting, 13% venting in this case, can promote flame acceleration due to turbulence produced by the flow through the vents in smooth channels. However, with obstacle-generated turbulence in the channel, 13% top venting was found to be beneficial. Flame acceleration resulting in DDT was shown to occur in as little as 35 liters of mixture. Comparison of the DDT data with obstacles in MINIFLAME and FLAME supports d/{lambda} scaling of DDT, where {lambda} is the detonation cell width of the mixture and d is the characteristic open diameter of the channel. In the MINIFLAME and FLAME tests, DDT occurred for d/{lambda} greater than approximately three. Comparison with other experiments shows that the value of d/{lambda} for DDT is not constant but depends on the obstacle type, spacing, and channel geometry. The comparison of MINIFLAME and FLAME experiments extends the use of d/{lambda} scaling to different geometries and larger scales than previous studies. Small-scale-model testing of flame acceleration and DDT with the same combustible mixture as the full-scale prototype underpredicts flame speeds, overpressures, and the possibility of DDT. 18 refs., 16 figs.

  18. Flame Interactions in Turbulent Premixed Twin V-flames

    E-Print Network [OSTI]

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

    2013-01-16T23:59:59.000Z

    diminish with increasing turbulence intensity, and so it is unlikely that any significant influence remains within the regions of interest for the flames presented here. It should also be noted that no energy is added to the flow in the current implemen... . A flow-chart summary is given in Fig. 2, and an example of the procedure applied to two-dimensional test data is shown in Fig. 3. The AFE procedure used here comprises three principal stages: (1) the binarised c field data from two successive time...

  19. Correlation of flame speed with stretch in turbulent premixed methane/air flames

    SciTech Connect (OSTI)

    Chen, J.H.; Im, Hong G.

    1997-11-01T23:59:59.000Z

    In the flamelet approach of turbulent premixed combustion, the flames are modeled as a wrinkled surface whose propagation speed, termed the {open_quotes}displacement speed,{close_quotes} is prescribed in terms of the local flow field and flame geometry. Theoretical studies suggest a linear relation between the flame speed and stretch for small values of stretch, S{sub L}/S{sub L}{sup 0} = 1 - MaKa, where S{sub L}{sup 0} is the laminar flame speed, Ka = {kappa}{delta}{sub F}/S{sub L}{sup 0} is the nondimensional stretch or the Karlovitz number, and Ma = L/{delta}{sub F} is the Markstein number. The nominal flame thickness, {delta}{sub F}, is determined as the ratio of the mass diffusivity of the unburnt mixture to the laminar flame speed. Thus, the turbulent flame model relies on an accurate estimate of the Markstein number in specific flame configurations. Experimental measurement of flame speed and stretch in turbulent flames, however, is extremely difficult. As a result, measurement of flame speeds under strained flow fields has been made in simpler geometries, in which the effect of flame curvature is often omitted. In this study we present results of direct numerical simulations of unsteady turbulent flames with detailed methane/air chemistry, thereby providing an alternative method of obtaining flame structure and propagation statistics. The objective is to determine the correlation between the displacement speed and stretch over a broad range of Karlovitz numbers. The observed response of the displacement speed is then interpreted in terms of local tangential strain rate and curvature effects. 13 refs., 3 figs.

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

    SciTech Connect (OSTI)

    Choudhuri, Ahsan

    2013-05-30T23:59:59.000Z

    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.

  1. Modelling of turbulent stratified flames

    E-Print Network [OSTI]

    Darbyshire, Oliver Richard

    ) shows data with a negative correlation, (b) shows data with no correlation and (c) shows data with a positive correlation. . . . . . . . . 44 3.3 Flow chart of the SIMPLE algorithm. . . . . . . . . . . . . . . . . . . . . 50 3.4 Schematic of the V... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 4.1 Comparison of predicted and measured velocities (m/s) and turbulence kinetic energy (m2/s2) for the cold flow ORACLES experiment. . . . . . 64 4.2 Comparison of cold flow results for the V-flame case. Mean axial velocity is shown on the left...

  2. The time evolution of a vortex-flame interaction observed via planar imaging of CH and OH

    SciTech Connect (OSTI)

    Nguyen, Quang-Viet; Paul, P.H.

    1996-05-01T23:59:59.000Z

    Planar laser-induced fluorescence imaging diagnostics of OH and CH are used to examine a premixed laminar flame subjected to a strong line-vortex pair. Results are reported for a fuel-rcih lamiar CH{sub 4}-air-N{sub 2} rod-stabilized flame. The flow studied was highly reproducible, which enabled the use of phase-sampled imaging to provide time-resolved image sequences. Image sequences are shown for a condition sufficient to produce localized extinction of the primary flame. Results indicate that a breakage in the CH front is not preceded by any distinct change in the OH front. The structure of the CH and OH profiles during the transient leading up to, and through the breakage of the CH front do not appear to be consistent with the concept of a strained laminar flame.

  3. 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)

    2010-07-15T23:59:59.000Z

    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)

  4. 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. [and others

    1996-02-01T23:59:59.000Z

    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.

  5. 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)

    1993-12-01T23:59:59.000Z

    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.

  6. atomic-absorption flame photometry: Topics by E-print Network

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

    to modeling thermonuclear flames CiteSeer Summary: Turbulence-flame interactions of thermonuclear fusion flames occurring in Type Ia Supernovae were studied by means of...

  7. 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)

    2010-01-15T23:59:59.000Z

    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)

  8. Flame Spectral Analysis for Boiler Control

    E-Print Network [OSTI]

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

    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...

  9. Theory of DDT in unconfined flames

    E-Print Network [OSTI]

    Khokhlov, A M; Wheeler, J C; Wheeler, J Craig

    1996-01-01T23:59:59.000Z

    This paper outlines a theoretical approach for predicting the onset of detonation in unconfined turbulent flames which is relevant both to problems of terrestrial combustion and to thermonuclear burning in Type Ia supernovae. Two basic assumuptions are made: 1) the gradient mechanism is the inherent mechanism that leads to DDT in unconfined conditions, and 2) the sole mechanism for preparing the gradient in induction time is by turbulent mixing and local flame quenching. The criterion for DDT is derived in terms of the one-dimensional detonation wave thickness, the laminar flame speed, and the laminar flame thickness in the reactive gas. This approach gives a lower-bound criterion for DDT for conditions where shock preheating, wall effects, and interactions with obstacles are absent. Regions in parameter space where unconfined DDT can and cannot occur are determined. A subsequent paper will address these issues specifically in the astrophysical context.

  10. Theory of DDT in Unconfined Flames

    E-Print Network [OSTI]

    A. M. Khokhlov; E. S. Oran; J. Craig Wheeler

    1996-05-15T23:59:59.000Z

    This paper outlines a theoretical approach for predicting the onset of detonation in unconfined turbulent flames which is relevant both to problems of terrestrial combustion and to thermonuclear burning in Type Ia supernovae. Two basic assumuptions are made: 1) the gradient mechanism is the inherent mechanism that leads to DDT in unconfined conditions, and 2) the sole mechanism for preparing the gradient in induction time is by turbulent mixing and local flame quenching. The criterion for DDT is derived in terms of the one-dimensional detonation wave thickness, the laminar flame speed, and the laminar flame thickness in the reactive gas. This approach gives a lower-bound criterion for DDT for conditions where shock preheating, wall effects, and interactions with obstacles are absent. Regions in parameter space where unconfined DDT can and cannot occur are determined. A subsequent paper will address these issues specifically in the astrophysical context.

  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. On the critical flame radius and minimum ignition energy for spherical flame initiation

    E-Print Network [OSTI]

    Ju, Yiguang

    , methane, and propane). The emphasis is placed on investigating the critical flame radius controlling to the cube of the critical flame radius. Furthermore, preferential diffusion of heat and mass (i.e. the Lewis igni- tion energy. Ã? 2010 The Combustion Institute. Published by Elsevier Inc. All rights reserved

  13. Virtual impactor

    DOE Patents [OSTI]

    Yeh, H.C.; Chen, B.T.; Cheng, Y.S.; Newton, G.J.

    1988-08-30T23:59:59.000Z

    A virtual impactor is described having improved efficiency and low wall losses in which a core of clean air is inserted into the aerosol flow while aerosol flow is maintained adjacent to the inner wall surfaces of the focusing portion of the impactor. The flow rate of the core and the length of the throat of the impactor's collection probe, as well as the dimensional relationships of other components of the impactor adjacent the separation region of the impactor, are selected to optimize separation efficiency. 4 figs.

  14. Ultraviolet imaging of hydrogen flames

    SciTech Connect (OSTI)

    Yates, G.J.; Wilke, M.; King, N.

    1988-01-01T23:59:59.000Z

    We have assembled an ultraviolet-sensitive intensified camera for observing hydrogen combustion by imaging the OH, A/sup 2/..sigma.. - X/sup 2//Pi/ bandhead emissions near 309 nm. The camera consists of a quartz and CaF achromat lense-coupled to an ultraviolet image intensifier which is in turn fiber-coupled to a focus projection scan (FPS) vidicon. The emission band is selected with interference filters which serve to discriminate against background. The camera provides optical gain of 100 to 1000 and is capable of being shuttered at nanosecond speeds and of being framed at over 600 frames per second. We present data from observations of test flames in air at standard RS-170 video rates with varying background conditions. Enhanced images using background subtraction are presented. Finally, we discuss the use of polarizaton effects to further discrimination against sky background. This work began as a feasibility study to investigate ultraviolet technology to detect hydrogen fires for the NASA space program. 6 refs., 7 figs, 2 tabs.

  15. Aromatics oxidation and soot formation in flames

    SciTech Connect (OSTI)

    Howard, J.B.; Pope, C.J.; Shandross, R.A.; Yadav, T.

    1993-04-01T23:59:59.000Z

    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 confirm or determine rate constants for, the main benzene oxidation reactions in flames, and to characterize soot and fullerenes and their formation mechanisms and kinetics. Stable and radical species profiles in the aromatics oxidation study are measured using molecular beam sampling with on-line mass spectrometry. The rate of soot formation measured by conventional optical techniques is found to support the hypotheses that particle inception occurs through reactive coagulation of high molecular weight PAH in competition with destruction by OHattack, and that the subsequent growth of the soot mass occurs through addition reactions of PAH and C[sub 2]H[sub 2] with the soot particles. During the first year of this reporting period, fullerenes C[sub 60] and C[sub 70] in substantial quantities were found in the flames being studied. The fullerenes were recovered, purified and spectroscopically identified. The yields of C[sub 60] and C[sub 70] were then determined over ranges of conditions in low-pressure premixed flames of benzene and oxygen.

  16. Paper # A02 Topic: Laminar Flames US Combustion Meeting

    E-Print Network [OSTI]

    Seitzman, Jerry M.

    been focused on synthetic fuel gas (syngas) combustion. Syngas is derived from coal through of the flame speeds of syngas mixtures.3-5 For example, stretch corrected laminar flame speed measurements

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

    SciTech Connect (OSTI)

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

    2013-07-03T23:59:59.000Z

    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.

  18. Pentan isomers compound flame front structure

    SciTech Connect (OSTI)

    Mansurov, Z.A.; Mironenko, A.W.; Bodikov, D.U.; Rachmetkaliev, K.N. [Kazakh Al-Farabi State National Univ., Almaty (Kazakhstan)

    1995-08-13T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Gülder, �mer L.

    premixed combustion diagrams. Small-scale transport of heat and species may be more important and chemistryFLAME 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

  20. 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

  1. Computatonal and experimental study of laminar flames

    SciTech Connect (OSTI)

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

    1993-12-01T23:59:59.000Z

    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.

  2. The effect of flame structure on soot formation and transport in turbulent nonpremixed flames using direct numerical simulation

    SciTech Connect (OSTI)

    Lignell, David O. [Department of Chemical Engineering, University of Utah, Salt Lake City, UT 84098 (United States); Reacting Flow Research Department, Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551 (United States); Chen, Jacqueline H. [Reacting Flow Research Department, Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551 (United States); Smith, Philip J. [Department of Chemical Engineering, University of Utah, Salt Lake City, UT 84098 (United States); Lu, Tianfeng; Law, Chung K. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08540 (United States)

    2007-10-15T23:59:59.000Z

    Direct numerical simulations of a two-dimensional, nonpremixed, sooting ethylene flame are performed to examine the effects of soot-flame interactions and transport in an unsteady configuration. A 15-step, 19-species (with 10 quasi-steady species) chemical mechanism was used for gas chemistry, with a two-moment, four-step, semiempirical soot model. Flame curvature is shown to result in flames that move, relative to the fluid, either toward or away from rich soot formation regions, resulting in soot being essentially convected into or away from the flame. This relative motion of flame and soot results in a wide spread of soot in the mixture fraction coordinate. In regions where the center of curvature of the flame is in the fuel stream, the flame motion is toward the fuel and soot is located near the flame at high temperature and hence has higher reaction rates and radiative heat fluxes. Soot-flame breakthrough is also observed in these regions. Fluid convection and flame displacement velocity relative to fluid convection are of similar magnitudes while thermophoretic diffusion is 5-10 times lower. These results emphasize the importance of both unsteady and multidimensional effects on soot formation and transport in turbulent flames. (author)

  3. COMBUSTION AND FLAME 24, 27-34 (1975) 27 Flame Emission Studies of Ozone with Metal Alkyls

    E-Print Network [OSTI]

    Zare, Richard N.

    COMBUSTION AND FLAME 24, 27-34 (1975) 27 Flame Emission Studies of Ozone with Metal Alkyls: Zn (CH3 of combustion. Premixed [2, 3] anddiffusion [4] flames of metal alkyl compounds have been carried out to deter- tageous to study the combustion of polyatomic molecules under single-collision conditions, i

  4. Virtual button interface

    DOE Patents [OSTI]

    Jones, Jake S. (Albuquerque, NM)

    1999-01-01T23:59:59.000Z

    An apparatus and method of issuing commands to a computer by a user interfacing with a virtual reality environment. To issue a command, the user directs gaze at a virtual button within the virtual reality environment, causing a perceptible change in the virtual button, which then sends a command corresponding to the virtual button to the computer, optionally after a confirming action is performed by the user, such as depressing a thumb switch.

  5. Virtual button interface

    DOE Patents [OSTI]

    Jones, J.S.

    1999-01-12T23:59:59.000Z

    An apparatus and method of issuing commands to a computer by a user interfacing with a virtual reality environment are disclosed. To issue a command, the user directs gaze at a virtual button within the virtual reality environment, causing a perceptible change in the virtual button, which then sends a command corresponding to the virtual button to the computer, optionally after a confirming action is performed by the user, such as depressing a thumb switch. 4 figs.

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

    E-Print Network [OSTI]

    Hicks, E P

    2015-01-01T23:59:59.000Z

    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...

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

    SciTech Connect (OSTI)

    Jackson, Aaron P. [Laboratories for Computational Physics and Fluid Dynamics, Naval Research Laboratory, Washington, DC (United States); Townsley, Dean M. [Department of Physics and Astronomy, The University of Alabama, Tuscaloosa, AL (United States); Calder, Alan C. [Department of Physics and Astronomy, The State University of New York - Stony Brook, Stony Brook, NY (United States)

    2014-04-01T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Liberman, M A; Kiverin, A D

    2015-01-01T23:59:59.000Z

    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...

  9. Environmentally Benign Flame Retardant Nanocoatings for Fabric

    E-Print Network [OSTI]

    Li, Yu-Chin

    2012-07-16T23:59:59.000Z

    nanocomposites in an effort to produce more flame-retardant coatings. Laponite and montmorillonite (MMT) clay were paired with branched poly(ethylenimine) to create thin film assemblies that can be tailored by changing pH and concentration of aqueous deposition...

  10. Environmentally Benign Flame Retardant Nanocoatings for Fabric 

    E-Print Network [OSTI]

    Li, Yu-Chin

    2012-07-16T23:59:59.000Z

    nanocomposites in an effort to produce more flame-retardant coatings. Laponite and montmorillonite (MMT) clay were paired with branched poly(ethylenimine) to create thin film assemblies that can be tailored by changing pH and concentration of aqueous deposition...

  11. AIAA 010189 Ignition and Flame Studies for

    E-Print Network [OSTI]

    Liu, Feng

    beyond the turbine blade material limit. Sirignano and Liu1,2 show by thermodynamic analysis-dimensional diffusion flame in a transonic flow with large pressure gradients typical of conditions in a turbine passage-to-weight ratio and to widen the range of engine operation. Since the flow in a turbine passage is accelerating

  12. 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. [Massachusetts Institute of Technology, Department of Mechanical Engineering, Cambridge, MA 02139 (United States)

    2009-05-15T23:59:59.000Z

    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)

  13. Flame Propagation of Butanol Isomers/Air Mixtures

    SciTech Connect (OSTI)

    Veloo, Peter S.; Egolfopoulos, Fokion N.

    2011-01-01T23:59:59.000Z

    An experimental and computational study was conducted on the propagation of flames of saturated butanol isomers. The experiments were performed in the counterflow configuration under atmospheric pressure, unburned mixture temperature of 343 K, and for a wide range of equivalence ratios. The experiments were simulated using a recent kinetic model for the four isomers of butanol. Results indicate that n-butanol/air flames propagate somewhat faster than both sec-butanol/air and iso-butanol/air flames, and that tert-butanol/air flames propagate notably slower compared to the other three isomers. Reaction path analysis of tert-butanol/air flames revealed that iso-butene is a major intermediate, which subsequently reacts to form the resonantly stable iso-butenyl radical retarding thus the overall reactivity of tert-butanol/air flames relatively to the other three isomers. Through sensitivity analysis, it was determined that the mass burning rates of sec-butanol/air and iso-butanol/air flames are sensitive largely to hydrogen, carbon monoxide, and C{sub 1}–C{sub 2} hydrocarbon kinetics and not to fuel-specific reactions similarly to n-butanol/air flames. However, for tert-butanol/air flames notable sensitivity to fuel-specific reactions exists. While the numerical results predicted closely the experimental data for n-butanol/air and sec-butanol/air flames, they overpredicted and underpredicted the laminar flame speeds for iso-butanol/air and tert-butanol/air flames respectively. It was demonstrated further that the underprediction of the laminar flame speeds of tert-butanol/air flames by the model was most likely due to deficiencies of the C{sub 4}-alkene kinetics.

  14. Detailed investigation of a pulverized fuel swirl flame in CO{sub 2}/O{sub 2} atmosphere

    SciTech Connect (OSTI)

    Toporov, D.; Bocian, P.; Heil, P.; Kellermann, A.; Stadler, H.; Tschunko, S.; Foerster, M.; Kneer, R. [Institute of Heat and Mass Transfer, RWTH Aachen University, Eilfschornsteinstrasse 18, D-52056 Aachen (Germany)

    2008-12-15T23:59:59.000Z

    A novel approach to oxycoal flame stabilization has been developed at the Institute of Heat and Mass Transfer at RWTH Aachen University [D. Toporov, M. Foerster, R. Kneer, in: Third Int. Conf. on Clean Coal Technologies for Our Future, Cagliari, Sardinia, Italy, 15-17 May 2007]. The swirl burner design and its operating conditions have been adjusted in order to enforce CO formation thus stabilizing the flame and obtaining a full burnout at levels of O{sub 2} content in the O{sub 2}/CO{sub 2} mixture similar to those in air. The paper presents results of detailed numerical and experimental investigations of a stable oxy-fired pulverized coal swirl flame (type-2) obtained with a 21 vol% O{sub 2} concentration. The combustion tests were performed in a vertical pilot-scale furnace (100 kW{sub th}) in the framework of the OXYCOAL-AC research project aiming to develop a membrane-based oxyfuel process. The experimental results concerning gas velocities, gas and particle temperatures, and gas compositions are presented and discussed, focusing on the underlying mechanisms as well as on the aerodynamics of the oxycoal flame. A comparison between measurements and simulations has shown the validity of the numerical method used. The reported data set can be used for validation of numerical models developed for prediction of oxyfuel combustion. (author)

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

    DOE Patents [OSTI]

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

    1992-01-01T23:59:59.000Z

    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.

  16. VIRTUAL REALITYVIRTUAL REALITY Introduction

    E-Print Network [OSTI]

    Petriu, Emil M.

    Animation Script Sensor Data Fusion & Interpretation Avatar (of a human or of a real object) VIRTUAL SCENE;HUMAN PERCEPTION OF REALITY REAL WORLD / ENVIRONMENT HUMAN (sentient living animal able of sensible Is Virtual Reality? -A Web-Based Introduction, by Jerry Isdale #12;Virtual Environments allow humans

  17. Non-premixed acoustically perturbed swirling flame dynamics

    SciTech Connect (OSTI)

    Idahosa, Uyi; Saha, Abhishek; Xu, Chengying; Basu, Saptarshi [Department of Mechanical, Materials and Aerospace Engineering, University of Central Florida, Orlando, FL (United States)

    2010-09-15T23:59:59.000Z

    An investigation into the response of non-premixed swirling flames to acoustic perturbations at various frequencies (f{sub p}=0-315 Hz) and swirl intensities (S=0.09 and 0.34) is carried out. Perturbations are generated using a loudspeaker at the base of an atmospheric co-flow burner with resulting velocity oscillation amplitudes vertical stroke u'/U{sub avg} vertical stroke in the 0.03-0.30 range. The dependence of flame dynamics on the relative richness of the flame is investigated by studying various constant fuel flow rate flame configurations. Flame heat release rate is quantitatively measured using a photomultiplier with a 430 nm bandpass filter for observing CH* chemiluminescence which is simultaneously imaged with a phase-locked CCD camera. The flame response is observed to exhibit a low-pass filter characteristic with minimal flame response beyond pulsing frequencies of 200 Hz. Flames at lower fuel flow rates are observed to remain attached to the central fuel pipe at all acoustic pulsing frequencies. PIV imaging of the associated isothermal fields show the amplification in flame aspect ratio is caused by the narrowing of the inner recirculation zone (IRZ). Good correlation is observed between the estimated flame surface area and the heat release rate signature at higher swirl intensity flame configurations. A flame response index analogous to the Rayleigh criterion in non-forced flames is used to assess the potential for a strong flame response at specific perturbation configurations and is found to be a good predictor of highly responsive modes. Phase conditioned analysis of the flame dynamics yield additional criteria in highly responsive modes to include the effective amplitude of velocity oscillations induced by the acoustic pulsing. In addition, highly responsive modes were characterized by velocity to heat release rate phase differences in the {+-}{pi}/2 range. A final observed characteristic in highly responsive flames is a Strouhal number between 1 and 3.5 based on the burner co-flow annulus diameter (St = f{sub p}U{sub avg}/d{sub m}). Finally, wavelet analyses of heat release rate perturbations indicate highly responsive modes are characterized by sustained low frequency oscillations which accompany the high amplitude velocity perturbations at these modes. Higher intensity low frequency heat release rate oscillations are observed for lean flame/low pulsing frequency conditions. (author)

  18. Correlation of flame speed with stretch in turbulent premixed methane/air flames

    SciTech Connect (OSTI)

    Chen, J.H.; Im, H.G.

    1998-03-01T23:59:59.000Z

    Direct numerical simulations of two-dimensional unsteady premixed methane/air flames are performed to determine the correlation of flame speed with stretch over a wide range of curvatures and strain rates generated by intense two-dimensional turbulence. Lean and stoichiometric premixtures are considered with a detailed C{sub 1}-mechanism for methane oxidation. The computed correlation shows the existence of two distinct stable branches. It further shows that exceedingly large negative values of stretch can be obtained solely through curvature effects which give rise to an overall nonlinear correlation of the flame speed with stretch. Over a narrower stretch range, {minus}1 {le} Ka {le} 1, which includes 90% of the sample, the correlation is approximately linear, and hence, the asymptotic theory for stretch is practically applicable. Overall, one-third of the sample has negative stretch. In this linear range, the Markstein number associated with the positive branch is determined and is consistent with values obtained from comparable steady counterflow computations. In addition to this conventional positive branch, a negative branch is identified. This negative branch occurs when a flame cusp, with a center of curvature in the burnt gases, is subjected to intense compressive strain, resulting in a negative displacement speed. Negative flame speeds are also encountered for extensive tangential strain rates exceeding a Karlovitz number of unity, a value consistent with steady counterflow computations.

  19. Numerical Simulation of a Premixed Turbulent V-Flame1 , M. S. Day, J. F. Grcar, M. J. Lijewski, M. Johnson, R. K. Cheng and I. G. Shepherd

    E-Print Network [OSTI]

    Bell, John B.

    diffusion. The chemical kinetics are modeled using the DRM- 19 methane mechanism, containing 21 chemical-stabilized premixed turbulent V-flame. The computations use an adaptive projection method based on a low Mach number formulation that incorpo- rates detailed chemical kinetics and transport. The simulations are performed

  20. 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.

  1. 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)

    1997-09-01T23:59:59.000Z

    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.

  2. Soot Deposit Properties in Practical Flames

    SciTech Connect (OSTI)

    Preciado, Ignacio [University of Utah; Eddings, Eric G. [University of Utah; Sarofim, Adel F. [University of Utah; Dinwiddie, Ralph Barton [ORNL; Porter, Wallace D [ORNL; Lance, Michael J [ORNL

    2009-01-01T23:59:59.000Z

    Soot deposition from hydrocarbon flames was investigated in order to evaluate the evolution of the deposits during the transient process of heating an object that starts with a cold metal surface that is exposed to a flame. The study focused on the fire/metal surface interface and the critical issues associated with the specification of the thermal boundaries at this interface, which include the deposition of soot on the metal surface, the chemical and physical properties of the soot deposits and their subsequent effect on heat transfer to the metal surface. A laboratory-scale device (metallic plates attached to a water-cooled sampling probe) was designed for studying soot deposition in a laminar ethylene-air premixed flame. The metallic plates facilitate the evaluation of the deposition rates and deposit characteristics such as deposit thickness, bulk density, PAH content, deposit morphology, and thermal properties, under both water-cooled and uncooled conditions. Additionally, a non-intrusive Laser Flash Technique (in which the morphology of the deposit is not modified) was used to estimate experimental thermal conductivity values for soot deposits as a function of deposition temperature (water-cooled and uncooled experiments), location within the flame and chemical characteristics of the deposits. Important differences between water-cooled and uncooled surfaces were observed. Thermophoresis dominated the soot deposition process and enhanced higher deposition rates for the water-cooled experiments. Cooler surface temperatures resulted in the inclusion of increased amounts of condensable hydrocarbons in the soot deposit. The greater presence of condensable material promoted decreased deposit thicknesses, larger deposit densities, different deposit morphologies, and higher thermal conductivities.

  3. Clothes That Care -- Flame Resistant Protection.

    E-Print Network [OSTI]

    Kerbel, Claudia

    1980-01-01T23:59:59.000Z

    fabrics , how to care for FR clothing, how consumers can express opinions about flame-resistant gar ments and how consumers can avoid fires at home. Protection For . .. Certain groups are more likely to be involved in clothing fire accidents than... fr quently than in their proportional share of the population . People whose reflexes are slowed by drugs , alcohol , physical disability or mental illness are also susceptible to injury or death by fire be cause they cannot respond quickly...

  4. Simulation of spherically expanding turbulent premixed flames

    E-Print Network [OSTI]

    Ahmed, I.; Swaminathan, N.

    2013-09-16T23:59:59.000Z

    canonically im- portant configuration and its investigation is helpful to understand combustion in prac- tical devices such as the spark ignited internal combustion engine, modern stratified charge engines and accidental explosions of fuel vapour cloud... Simulation of spherically expanding turbulent premixed flames I. Ahmed, N. Swaminathan? Department of Engineering, Cambridge University, Cambridge, CB2 1PZ, UK. ?Corresponding author: Department of Engineering, Cambridge University, Trumpington...

  5. Analyzing and Tracking Burning Structures in Lean Premixed Hydrogen Flames

    E-Print Network [OSTI]

    Bremer, Peer-Timo

    2010-01-01T23:59:59.000Z

    structures in lean premixed hydrogen ?ames. Combustion andStructures in Lean Premixed Hydrogen Flames P. -T. Bremersimulations of lean hydrogen ?ames subject to different

  6. Soot precursor measurements in benzene and hexane diffusion flames

    SciTech Connect (OSTI)

    Kobayashi, Y.; Furuhata, T.; Amagai, K.; Arai, M. [Department of Mechanical System Engineering, Graduate School of Engineering, Gunma University, 1-5-1 Tenjin-cho, Kiryu-shi, Gunma 376-8515 (Japan)

    2008-08-15T23:59:59.000Z

    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)

  7. adiabatic flame temperature: Topics by E-print Network

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

    initial temperature 0 296 Knyazev, Vadim D. 6 Temperature field reconstruction of combustion flame based on high Engineering Websites Summary: radiant existence field on camera...

  8. FIELD TEST OF THE FLAME QUALITY INDICATOR

    SciTech Connect (OSTI)

    Andrew M. Rudin; Thomas Butcher; Henry Troost

    2003-02-04T23:59:59.000Z

    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.

  9. Non-Sooting, Low Flame Temperature Mixing-Controlled DI Diesel...

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

    Sooting, Low Flame Temperature Mixing-Controlled DI Diesel Combustion Non-Sooting, Low Flame Temperature Mixing-Controlled DI Diesel Combustion 2003 DEER Conference Presentation:...

  10. Effect of Synthesis Condition and Annealing on the Sensitivity and Stability of Gas Sensors Made of Zn-Doped y-Fe2O3 Particles 

    E-Print Network [OSTI]

    Kim, Taeyang

    2010-10-12T23:59:59.000Z

    In this study, the effect of synthesis conditions and annealing process on the sensitivity and stability of gas sensors made of flame-synthesized Zn-doped ?-Fe2O3 particles was investigated. Zn-doped ?-Fe2O3 particles were synthesized by flame...

  11. Effect of Synthesis Condition and Annealing on the Sensitivity and Stability of Gas Sensors Made of Zn-Doped y-Fe2O3 Particles

    E-Print Network [OSTI]

    Kim, Taeyang

    2010-10-12T23:59:59.000Z

    In this study, the effect of synthesis conditions and annealing process on the sensitivity and stability of gas sensors made of flame-synthesized Zn-doped ?-Fe2O3 particles was investigated. Zn-doped ?-Fe2O3 particles were synthesized by flame...

  12. Lean and ultralean stretched propane-air counterflow flames

    SciTech Connect (OSTI)

    Cheng, Zhongxian; Pitz, Robert W. [Mechanical Engineering Department, Vanderbilt University, Box 1592, Station B, Nashville, TN 37235 (United States); Wehrmeyer, Joseph A. [Aerospace Testing Alliance, Building 1099, Avenue C, Arnold Air Force Base, TN 37389 (United States)

    2006-06-15T23:59:59.000Z

    Stretched laminar flame structures for a wide range of C{sub 3}H{sub 8}-air mixtures vs hot products are investigated by laser-based diagnostics and numerical simulation. The hot products are produced by a lean H{sub 2}-air premixed flame. The effect of stretch rate and equivalence ratio on four groups of C{sub 3}H{sub 8}-air flame structures is studied in detail by Raman scattering measurements and by numerical calculations of the major species concentration and temperature profiles. The equivalence ratio, f, is varied from a near-stoichiometric condition (f=0.86) to the sublean limit (f=0.44) and the stretch rate varies from 90 s{sup -1} to near extinction. For most of these C{sub 3}H{sub 8}-air lean mixtures, hot products are needed to maintain the flame. The significant feature of these flames is the relatively low flame temperatures (1200-1800 K). For this temperature range, the predicted C{sub 3}H{sub 8}-air flame structure is sensitive to the specific chemical kinetic mechanism. Two types of flame structures (a lean self-propagating flame and a lean diffusion-controlled flame) are obtained based on the combined effect of stretch and equivalence ratio. Three different mechanisms, the M5 mechanism, the Optimized mechanism, and the San Diego mechanism, are chosen for the numerical simulations. None of the propane chemical mechanisms give good agreement with the data over the entire range of flame conditions. (author)

  13. Adaptive low Mach number simulations of nuclear flame microphysics

    E-Print Network [OSTI]

    Bell, John B.

    Adaptive low Mach number simulations of nuclear flame microphysics J. B. Bell, M. S. Day, C. A of nuclear flames in Type Ia su- pernovae. This model is based on a low Mach number formulation nuclear burning. The formulation presented here generalizes low Mach number models used in combustion

  14. Vortex phase-jitter in acoustically excited bluff body flames

    E-Print Network [OSTI]

    Lieuwen, Timothy C.

    Vortex phase-jitter in acoustically excited bluff body flames Santosh J. Shanbhogue, Michael disturbances. Phase locked particle image velocimetry was carried out over a range of conditions", manifested as cycle-to-cycle variation in flame and vorticity field at the same excitation phase. Phase

  15. Iron/soot interaction in a laminar ethylene nonpremixed flame

    SciTech Connect (OSTI)

    Zhang, J.; Megaridis, C.M. [Univ. of Illinois, Chicago, IL (United States). Dept. of Mechanical Engineering

    1994-12-31T23:59:59.000Z

    A laminar, coannular, ethylene/air nonpremixed flame doped with ferrocene additive is employed to address the fundamental question of how iron becomes incorporated into the carbonaceous soot phase, thus interfering with the soot formation processes. The structure and chemical composition of individual aggregates are characterized with respect to flame coordinates via a combination of thermophoretic sampling, transmission electron microscopy, and energy dispersive spectrometry. Soot aggregate microstructure clearly reveals iron occlusion, as well as stratification of soot layers over the occluded phase. The study provides physical evidence that the soot and iron compounds combine in the flame to form a hybrid (inhomogeneous) particulate phase. The reported observations are consistent with the hypothesis that ferrocene decomposes early in the combustion process and before the onset of soot particle inception, thus forming a fine aerosol for the subsequent deposition of carbonaceous substances. Examination of a series of inhomogeneous soot aggregates shows that the flame aerosol composition varies with flame coordinates. In particular, aggregates transported in the soot annulus near the luminous flame front are primarily composed of carbon and oxygen, with traces of iron finely dispersed through the aggregate matrix. On the other hand, carbonaceous soot transported at low heights and near the flame axis contains iron in its elemental form. Finally, soot aggregates in all other areas of the flame contain both iron and oxygen, thus implying the possible presence of iron oxides within the carbonaceous matrix.

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

    E-Print Network [OSTI]

    Cain, Amanda Ashley

    2014-12-09T23:59:59.000Z

    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. Bifurcations of flame filaments in chaotically mixed combustion reactions

    E-Print Network [OSTI]

    Gottwald, Georg A.

    Bifurcations of flame filaments in chaotically mixed combustion reactions Shakti N. Menon and Georg ranging fields. Be- sides in the case of combustion, where mixing-induced bifurcations may lead mixing has a significant effect on combustion processes and in particular on flame filamental structures

  18. SIEMENS-UV OPTICAL FLAME DETECTION MONA HEMENDRA RAITHATHA

    E-Print Network [OSTI]

    Sekhon, Jasjeet S.

    SIEMENS-UV OPTICAL FLAME DETECTION MONA HEMENDRA RAITHATHA College of Engineering University of tests conducted, as well as a cost and market analysis, the recommendation for Siemens would be to use.funginstitute.berkeley.edu #12;SIEMENS-UV OPTICAL FLAME DETECTION BY MONA HEMENDRA RAITHATHA THESIS Submitted in partial

  19. Measurements of Laminar Flame Velocity for Components of Natural Gas

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    flame velocity of components of natural gas, methane, ethane, propane, and nbutane as well as of binary% by volume (1). The laminar flame velocities of methane/air, ethane/air, and propane/air mixtures have on a plenum chamber with the radial temperature distribution measurement made by a series of thermocouples

  20. Modeling of NOx formation in circular laminar jet flames

    E-Print Network [OSTI]

    Siwatch, Vivek

    2007-04-25T23:59:59.000Z

    -premixed isolated circular laminar jet flame. The jet consists of the fuel rich inner region and the O2 rich outer region. The model estimates both thermal NOx and prompt NOx assuming single step kinetics for NOx formation and a thin flame model. Further the amount...

  1. 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)

    2014-05-15T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

    Yamada, Hiroyuki; Suzaki, Kotaro; Goto, Yuichi [National Traffic Safety and Environment Laboratory, 7-42-27 Jindaiji-Higashimachi, Chofu, Tokyo 182-0012 (Japan); Tezaki, Atsumu [Department of Mechanical and Intellectual Systems Engineering, University of Toyama, Gofuku 3190, Toyama-shi, Toyama 930-8555 (Japan)

    2008-07-15T23:59:59.000Z

    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)

  3. Electrical probe diagnostics for the laminar flame quenching distance

    SciTech Connect (OSTI)

    Karrer, Maxime; Makarov, Maxime [Renault Technocentre, 78288 Guyancourt Cedex (France); Bellenoue, Marc; Labuda, Sergei; Sotton, Julien [Laboratoire de Combustion et de Detonique, CNRS, 86961 Futuroscope Chasseneuil (France)

    2010-02-15T23:59:59.000Z

    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)

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

    SciTech Connect (OSTI)

    Chakrabarty, Rajan K., E-mail: rajan.chakrabarty@gmail.com [Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130 (United States); Laboratory for Aerosol Science, Spectroscopy, and Optics, Desert Research Institute, Nevada System of Higher Education, Reno, Nevada 89512 (United States); Novosselov, Igor V. [Department of Mechanical Engineering, University of Washington, Seattle, Washington 98195 (United States); Enertechnix Inc., Maple Valley, Washington 98068 (United States); Beres, Nicholas D.; Moosmüller, Hans [Laboratory for Aerosol Science, Spectroscopy, and Optics, Desert Research Institute, Nevada System of Higher Education, Reno, Nevada 89512 (United States); Sorensen, Christopher M. [Condensed Matter Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States); Stipe, Christopher B. [TSI Incorporated, 500 Cardigan Rd, Shoreview, Minnesota 55126 (United States)

    2014-06-16T23:59:59.000Z

    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.

  5. Dynamics of premixed flames in a narrow channel with a step-wise wall temperature

    E-Print Network [OSTI]

    Daraio, Chiara

    . [1], in their experiments on methane/air and propane/air premixed flames in cylindrical tubes of 2 mm al. [10], asymmetric flames were found in fuel-lean methane/air mixtures burning in a rectangular flame structure was experi- mentally observed for lean propane/air flames in tubes at condi- tions close

  6. Interactive Virtual Environments Introduction

    E-Print Network [OSTI]

    Petriu, Emil M.

    sensor data or by animation scripts. Human users can interact and directly manipulate objects within Reality Interactive Virtual Reality Virtualized Reality Augmented Reality #12;HUMAN PERCEPTION OF REALITY REAL WORLD / ENVIRONMENT HUMAN (sentient living animal able of sensible reasoning) #12;Real

  7. GRAVITATIONALLY UNSTABLE FLAMES: RAYLEIGH-TAYLOR STRETCHING VERSUS TURBULENT WRINKLING

    SciTech Connect (OSTI)

    Hicks, E. P. [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and the Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208 (United States); Rosner, R., E-mail: eph2001@columbia.edu [Computation Institute, University of Chicago, 5735 S. Ellis Ave., Chicago, IL 60637 (United States)

    2013-07-10T23:59:59.000Z

    In this paper, we provide support for the Rayleigh-Taylor-(RT)-based subgrid model used in full-star simulations of deflagrations in Type Ia supernovae explosions. We use the results of a parameter study of two-dimensional direct numerical simulations of an RT unstable model flame to distinguish between the two main types of subgrid models (RT or turbulence dominated) in the flamelet regime. First, we give scalings for the turbulent flame speed, the Reynolds number, the viscous scale, and the size of the burning region as the non-dimensional gravity (G) is varied. The flame speed is well predicted by an RT-based flame speed model. Next, the above scalings are used to calculate the Karlovitz number (Ka) and to discuss appropriate combustion regimes. No transition to thin reaction zones is seen at Ka = 1, although such a transition is expected by turbulence-dominated subgrid models. Finally, we confirm a basic physical premise of the RT subgrid model, namely, that the flame is fractal, and thus self-similar. By modeling the turbulent flame speed, we demonstrate that it is affected more by large-scale RT stretching than by small-scale turbulent wrinkling. In this way, the RT instability controls the flame directly from the large scales. Overall, these results support the RT subgrid model.

  8. Measurements and large eddy simulation of propagating premixed flames

    SciTech Connect (OSTI)

    Masri, A.R.; Cadwallader, B.J. [School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW 2006 (Australia); Ibrahim, S.S. [Department of Aeronautical and Automotive Engineering, Loughborough University, Loughborough LE11 3TU (United Kingdom)

    2006-07-15T23:59:59.000Z

    This paper presents an experimental and numerical study of unsteady turbulent premixed flames igniting in an initially stagnant mixture and propagating past solid obstacles. The objective here is to study the outstanding issue of flow-flame interactions in transient premixed combustion environments. Particular emphasis is placed on the burning rate and the structure of the flame front. The experimental configuration consists of a chamber with a square cross-section filled with a combustible mixture of propane-air ignited from rest. An array of baffle plates as well as geometrical obstructions of varying shapes and blockage ratios, are placed in the path of the flame as it propagates from the ignition source to the vented end of the enclosure. A range of flame propagation conditions are studied experimentally. Measurements are presented for pressure-time traces, high-speed images of the flame front, mean velocities obtained from particle imaging velocimetry and laser induced fluorescence images of the hydroxyl radical OH. Three-dimensional large eddy simulations (LES) are also made for a case where a square obstacle and an array of baffle plates are placed in the chamber. The dynamic Germano model and a simple flamelet combustion model are used at the sub-grid scale. The effects of grid size and sub-grid filter width are also discussed. Calculations and measurements are found to be in good agreement with respect to flame structure and peak overpressure. Turbulence levels increase significantly at the leading edge of the flame as it propagates past the array of baffle plates and the obstacle. With reference to the regime diagrams for turbulent premixed combustion, it is noted that the flame continues to lie in the zones of thin reactions or corrugated flamelets regardless of the stage of propagation along the chamber. (author)

  9. Numerical Investigation of Scaling Properties of Turbulent Premixed Flames

    E-Print Network [OSTI]

    J. C. Niemeyer; A. R. Kerstein

    1997-07-09T23:59:59.000Z

    Gibson scaling and related properties of flame-surface geometry in turbulent premixed combustion are demonstrated using a novel computational model, Deterministic Turbulent Mixing (DTM). In DTM, turbulent advection is represented by a sequence of maps applied to the computational domain. The structure of the mapping sequence incorporates pertinent scaling properties of the turbulent cascade. Here, combustion in Kolmogorov turbulence (kinetic-energy cascade) and in Bolgiano-Obukhov convective turbulence (potential-energy cascade) is simulated. Implications with regard to chemical flames and astrophysical (thermonuclear) flames are noted.

  10. Designing a Virtual Manikin Animation Framework Aimed at Virtual Prototyping.

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    - of available new scientific techniques to animate Virtual Humans, in a new control scheme that better answersDesigning a Virtual Manikin Animation Framework Aimed at Virtual Prototyping. Antoine Rennuit1, 2, and analyse human behaviour in the product's environment (for maintenance, ergonomics...), thanks to Virtual

  11. CONSTRUCTING VIRTUAL HUMAN LIFE SIMULATIONS

    E-Print Network [OSTI]

    Kallmann, Marcelo

    , Virtual Environments, Behavioral Animation, Object Interaction, Python. 1. INTRODUCTION Virtual humanCONSTRUCTING VIRTUAL HUMAN LIFE SIMULATIONS Marcelo Kallmann, Etienne de Sevin and Daniel Thalmann human life simulations. Our main goal is to have virtual human actors living and working autonomously

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

    Energy Savers [EERE]

    flash and a flame . . . a rush and a roar . . . a bright white bird booming into a deep blue sky: Few science experiments ever begin in such spectacular fashion. Yet the Space...

  13. Temperature field reconstruction of combustion flame based on high

    E-Print Network [OSTI]

    that sound propagates in a different medium with different speed, and its theo- retical cornerstone-known materials of solid, liquid, and gaseous states, flame is a kind of plasma1,2 of which temper- ature is one

  14. TRACES Centre Thermo iCE 3500 Flame AA Spectrometer

    E-Print Network [OSTI]

    Wells, Mathew G. - Department of Physical and Environmental Sciences, University of Toronto

    TRACES Centre Thermo iCE 3500 Flame AA Spectrometer Standard Operating Procedure 1. Turn on the lamp icon a. ID the lamp of choice and click the `Off' button to `On' b. Non-Thermo lamps MUST

  15. Surface wettability studies of PDMS using flame plasma treatment

    E-Print Network [OSTI]

    Wang, Xin C

    2009-01-01T23:59:59.000Z

    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 ...

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

    E-Print Network [OSTI]

    Altay, Hurrem Murat

    2009-01-01T23:59:59.000Z

    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 ...

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

    SciTech Connect (OSTI)

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

    1993-12-01T23:59:59.000Z

    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.

  18. The inline virtual impactor

    E-Print Network [OSTI]

    Seshadri, Satyanarayanan

    2009-05-15T23:59:59.000Z

    A circumferential slot In-line Virtual Impactor (IVI) has been designed using Computational Fluid Dynamics (CFD) simulation tools and experimentally characterized using monodispersed liquid aerosols to validate simulation results. The base design...

  19. Jefferson Lab Virtual Tour

    SciTech Connect (OSTI)

    None

    2013-07-13T23:59:59.000Z

    Take a virtual tour of the campus of Thomas Jefferson National Accelerator Facility. You can see inside our two accelerators, three experimental areas, accelerator component fabrication and testing areas, high-performance computing areas and laser labs.

  20. Jefferson Lab Virtual Tour

    ScienceCinema (OSTI)

    None

    2014-05-22T23:59:59.000Z

    Take a virtual tour of the campus of Thomas Jefferson National Accelerator Facility. You can see inside our two accelerators, three experimental areas, accelerator component fabrication and testing areas, high-performance computing areas and laser labs.

  1. Influence of gas compression on flame acceleration in the early stage of burning in tubes

    E-Print Network [OSTI]

    Valiev, Damir; Kuznetsov, Mikhail; Eriksson, Lars-Erik; Law, Chung K; Bychkov, Vitaly

    2012-01-01T23:59:59.000Z

    The mechanism of finger flame acceleration at the early stage of burning in tubes has been observed experimentally by Clanet and Searby [Combust. Flame 105: 225 (1996)] for slow propane-air flames, and elucidated analytically and computationally by Bychkov et al. [Combust. Flame 150: 263 (2007)] in the limit of an incompressible flow. We analytically, experimentally and computationally study herein the finger flame acceleration for fast burning flames, when the gas compressibility assumes an important role. Specifically, we have developed a theory through small Mach number expansion up to the first-order terms, demonstrating that gas compression reduces the acceleration rate and thereby moderates the finger flame acceleration noticeably. We have also conducted experiments for hydrogen-oxygen mixtures with considerable initial values of the Mach number, showing finger flame acceleration with the acceleration rate much smaller than those obtained previously for hydrocarbon flames. Furthermore, we have performed...

  2. On the Evolution of Thermonuclear Flames on Large Scales

    E-Print Network [OSTI]

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

    2006-10-05T23:59:59.000Z

    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.

  3. Experimental and Computational Study of Flame Inhibition Mechanisms of Halogenated Compounds in C1-C3 Alkanes Flames

    E-Print Network [OSTI]

    Osorio Amado, Carmen H

    2013-07-30T23:59:59.000Z

    suppressants on ignition and laminar flame propagation of C_(1)-C_(3) alkanes premixed mixtures, as good representatives of flammable gas fires (Class B fires). This methodology integrates model formulations and experimental designs in order to examine both...

  4. Virtual data in CMS production

    SciTech Connect (OSTI)

    Arbree, A. et al.

    2004-08-26T23:59:59.000Z

    Initial applications of the GriPhyN Chimera Virtual Data System have been performed within the context of CMS Production of Monte Carlo Simulated Data. The GriPhyN Chimera system consists of four primary components: (1) a Virtual Data Language, which is used to describe virtual data products, (2) a Virtual Data Catalog, which is used to store virtual data entries, (3) an Abstract Planner, which resolves all dependencies of a particular virtual data product and forms a location and existence independent plan, (4) a Concrete Planner, which maps an abstract, logical plan onto concrete, physical grid resources accounting for staging in/out files and publishing results to a replica location service. A CMS Workflow Planner, MCRunJob, is used to generate virtual data products using the Virtual Data Language. Subsequently, a prototype workflow manager, known as WorkRunner, is used to schedule the instantiation of virtual data products across a grid.

  5. Flow field studies of a new series of turbulent premixed stratified flames

    SciTech Connect (OSTI)

    Seffrin, F.; Fuest, F.; Dreizler, A. [Technische Universitaet Darmstadt, Center of Smart Interfaces, Reaktive Stroemungen und Messtechnik, Petersenstr. 32, 64287 Darmstadt (Germany); Geyer, D. [Hochschule Darmstadt, Thermodynamik und Alternative Antriebe, Haardtring 100, 64295 Darmstadt (Germany)

    2010-02-15T23:59:59.000Z

    This paper presents a new burner design for lean premixed stratified combustion for experiments to validate models for numerical simulations. The burner demonstrates combustion phenomena relevant to technological applications, where flames are often turbulent, lean premixed, and stratified. The generic burner was designed for high Reynolds number flows and can stabilize a variety of different lean premixed flames. The burner's design and its versatile operational conditions are introduced. Shear, stratification, and fuel type are parametrically varied to provide a sound database of related flow configurations. Reacting and corresponding non-reacting configurations are examined. Experimental setups and the results of laser Doppler velocimetry (LDV) and particle image velocimetry (PIV) are presented and discussed. LDV measurements provide radial profiles of mean axial velocity, mean radial velocity, and turbulent kinetic energy as well as integral time scales. High-speed PIV is introduced as a novel technique to determine integral time and length scales and provide 2D 2-component velocity fields and related quantities, such as vorticity. (author)

  6. Modeling of the formation of short-chain acids in propane flames

    E-Print Network [OSTI]

    Battin-Leclerc, Frédérique; Jaffrezo, J L; Legrand, M

    2009-01-01T23:59:59.000Z

    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.

  7. Investigation of H2 Concentration and Combustion Instability Effects on the Kinetics of Strained Syngas Flames

    SciTech Connect (OSTI)

    Ahsan R. Choudhuri

    2006-08-07T23:59:59.000Z

    The flame extinction limits of syngas (H{sub 2}-CO) flames were measured using a twin-flame-counter-flow burner. Plots of Extinction limits vs. global stretch rates were generated at different mixture compositions and an extrapolation method was used to calculate the flame extinction limit corresponding to an experimentally unattainable zero-stretch condition. The zero-stretch extinction limit of H{sub 2}-CO mixtures decreases (from rich to lean) with the increase in H{sub 2} concentration in the mixture. The average difference between the measured flame extinction limit and the Le Chatelier's calculation is around {approx} 7%. The measured OH{sup -} chemiluminescent data indicates that regardless of mixture compositions the OH radical concentration reduces (within the experimental uncertainties) to an extinction value prior to the flame extinction. Flame extinction limits of H{sub 2}-CO mixtures measured in a flat-flame burner configuration also show a similar relation. Additionally, the measured laminar flame velocity close to the extinction indicates that regardless of fuel composition the premixed flame of hydrogen fuel blends extinguishes when the mixture laminar flame velocity falls below a critical value. The critical laminar flame velocity at extinction for H{sub 2}-CO premixed flames (measured in the flat flame burner configuration) is found to be 3.77({+-}0.38) cm/s. An externally perturbed H{sub 2}-CO twin flame was not experimentally achievable for the mixture conditions used in the present investigation. A slightest perturbation in the flow-field distorts the H{sub 2}-CO twin-flame. The flame becomes highly unstable with the introduction of an externally excited flow oscillation.

  8. The structure of the carbon black flame

    E-Print Network [OSTI]

    Anderson, W. Kermi

    1945-01-01T23:59:59.000Z

    BLACK FLAME A Dissertation By William Kermit Anderson THEHSR UCOF 120925 TNLKMDiserstsKa aony WHR1mo WdpvmlcyfEyS lnR1 R1WvpS 1nS nvfyARyfh vySS Rm R1y SyuyoWc nvfnunfHWcS Wvf fybWoRgyvRS l1m dmmbyoWRyf Rm gWpy R1nS lmop bmSSnAcy. xbydnWc R1Wvp...S Woy fHy Rm R1y PmccmlnvE gygAyoS mP R1y. SRWPP mP R1y TEondHcRHoWc Wvf tyd1WvndWc NmccyEy mP ayqWS. am eo. joyf D. :yvSyv Pmo Ryd1vndWc 1ycb Wvf Pmo vHgyomHS SHEEySRnmvS mP uWcHy. am eo. N. N. 9yfEyS Pmo PnvWvdnWc Wnf Wvf yqdych cyvR dmmbyo...

  9. ATLAS Virtual Visits

    E-Print Network [OSTI]

    Goldfarb, Steven; The ATLAS collaboration

    2015-01-01T23:59:59.000Z

    ATLAS Virtual Visits is a project initiated in 2011 for the Education & Outreach program of the ATLAS Experiment at CERN. Its goal is to promote public appreciation of the LHC physics program and particle physics, in general, through direct dialogue between ATLAS physicists and remote audiences. A Virtual Visit is an IP-based videoconference, coupled with a public webcast and video recording, between ATLAS physicists and remote locations around the world, that typically include high school or university classrooms, Masterclasses, science fairs, or other special events, usually hosted by collaboration members. Over the past two years, more than 10,000 people, from all of the world’s continents, have actively participated in ATLAS Virtual Visits, with many more enjoying the experience from the publicly available webcasts and recordings. We present an overview of our experience and discuss potential development for the future.

  10. High efficiency virtual impactor

    DOE Patents [OSTI]

    Loo, B.W.

    1980-03-27T23:59:59.000Z

    Environmental monitoring of atmospheric air is facilitated by a single stage virtual impactor for separating an inlet flow (Q/sub 0/) having particulate contaminants into a coarse particle flow (Q/sub 1/) and a fine particle flow (Q/sub 2/) to enable collection of such particles on different filters for separate analysis. An inlet particle acceleration nozzle and coarse particle collection probe member having a virtual impaction opening are aligned along a single axis and spaced apart to define a flow separation region at which the fine particle flow (Q/sub 2/) is drawn radially outward into a chamber while the coarse particle flow (Q/sub 1/) enters the virtual impaction opening.

  11. Online Games, Virtual Worlds, and Social Networks

    E-Print Network [OSTI]

    Hemmers, Oliver

    JOUR 447: Online Games, Virtual Worlds, and Social Networks Virtual Island Making #12;One element in the look and design of the virtual islands. JOUR 447: Online Games, Virtual Worlds, and Social Networks

  12. VirtualPower: Coordinated Power Management in Virtualized Enterprise Systems

    E-Print Network [OSTI]

    Yang, Junfeng

    VirtualPower: Coordinated Power Management in Virtualized Enterprise Systems Ripal Nathuji CERCS Institute of Technology Atlanta, GA 30032 schwan@cc.gatech.edu ABSTRACT Power management has become. This paper explores how to inte- grate power management mechanisms and policies with the virtualization

  13. 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)

    2010-10-15T23:59:59.000Z

    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)

  14. Measurements of the structure of turbulent premixed and stratified methane/air flames

    E-Print Network [OSTI]

    Sweeney, Mark

    2011-11-08T23:59:59.000Z

    was entirely due to deviation from stoichiometry and the corresponding reduction in local reaction rate. Poinsot et al [34] performed three-dimensional reduced chemistry simulations of turbulent strat- ified propane/air flames with a Gaussian distribution... that stratification increased the flame propagation rate. The local variation in burning velocity was accompanied by an increase in flame front wrinkling relative to premixed flames, with a corresponding broadening of curvature distributions. Pasquier et al [22...

  15. Fractal characterisation of high-pressure and hydrogen-enriched CH4air turbulent premixed flames

    E-Print Network [OSTI]

    Gülder, �mer L.

    Fractal characterisation of high-pressure and hydrogen-enriched CH4­air turbulent premixed flames measurements were performed to obtain the flame front images, which were further analyzed for fractal of the flame front curvature as a function of the pressure. Fractal dimension showed a strong dependence

  16. 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

  17. Kinetic effects of toluene blending on the extinction limit of n-decane diffusion flames

    E-Print Network [OSTI]

    Ju, Yiguang

    analyses of kinetic path ways and species transport on flame extinction were also conducted. The results and emission properties, such as the ignition delay times, extinction limits, flame speeds, species profilesKinetic effects of toluene blending on the extinction limit of n-decane diffusion flames Sang Hee

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

    E-Print Network [OSTI]

    Turbulent Oxygen Flames in Type Ia Supernovae A. J. Aspden1 , J. B. Bell1 , and S. E. Woosley2 oxygen flames. The two aims of the paper are to examine the response of the inductive oxygen flame to intense levels of turbulence, and to explore the possibility of transition to detonation in the oxygen

  19. Virtual Gateway Network Documentation

    E-Print Network [OSTI]

    Segall, Adrian

    Virtual Gateway Network Documentation Composed By: Stiven Andre Nikolai Gukov #12;Table of contents.3) VGNET as a network manager 2) VGNET explained 2.1) One PC with multiple Internet access points. 2 both routers. 1.3) VGNET as a network manager Let's look at figure 3 again. The perfect scenario we may

  20. Simulation of turbulent flames relevant to spark-ignition engines

    E-Print Network [OSTI]

    Ahmed, Irufan

    2014-04-29T23:59:59.000Z

    -premixed. In premixed flames, fuel and oxidiser are mixed homo- geneously before combustion. Lean-burn gas turbines for power generation and spark-ignition (SI) IC engines are typical examples of this type of combustion. In non-premixed or ‘diffusion flames’, the fuel... and oxidiser are transported sep- arately into the reaction zones by diffusion. Aero-engine gas turbines and diesel engines are typical examples of non-premixed combustion. It is often the case in practical systems that fuel and air is not completely mixed...

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

    E-Print Network [OSTI]

    Kolla, Hemanth

    2010-03-16T23:59:59.000Z

    closure for two mixtures: stoichiometric methane–air with K = 1.0 (•) and lean propane–air with KLe = 1.0 (?). The experimental data of Abdel- Gayed et al. (1987) for K = 1.0 are also shown (?). . . . . . . . . 111 7.9 The comparisons of flame speeds... closure for two mixtures: stoichiometric methane–air with K = 1.0 (•) and lean propane–air with KLe = 1.0 (?). The experimental data of Abdel- Gayed et al. (1987) for K = 1.0 are also shown (?). . . . . . . . . 111 7.9 The comparisons of flame speeds...

  2. INVESTIGATION ON THE FLAME EXTINCTION LIMIT OF FUEL BLENDS

    SciTech Connect (OSTI)

    Ahsan R. Choudhuri

    2005-02-01T23:59:59.000Z

    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.

  3. Spatial resolution of temperature and chemical species in a flame

    E-Print Network [OSTI]

    Albahadily, Fakhrildeen Niema

    1984-01-01T23:59:59.000Z

    by Winefordner et al. (51). AE . /k A. g. I. B. ln ~ + ln ? + 1n? 1 A. g. i B. (36) where: subscript i = the level excited by the source subscript j = the thermally assisted level flame temperature AE . . ij the difference in energy between i and j.... Schweikert (Member) Abdel-Kad Ayou (Memb ) Vaneica . Y ng (Member) May 1984 ABSTRACT Spatial Resolution of Temperature and Chemical Species in a Flame. (May 1984) Fakhrildeen Niema Albahadily, B. S. , University of Basrah/Iraq Chairman of Advisory...

  4. 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

    1999-05-07T23:59:59.000Z

    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.

  5. Extinction and near-extinction instability of non-premixed tubular flames

    SciTech Connect (OSTI)

    Hu, Shengteng; Pitz, Robert W.; Yu, Wang [Mechanical Engineering Department, Vanderbilt University, Nashville, TN 37235 (United States)

    2009-01-15T23:59:59.000Z

    Tubular non-premixed flames are formed by an opposed tubular burner, a new tool to study the effects of curvature on extinction and flame instability of non-premixed flames. Extinction of the opposed tubular flames generated by burning diluted H{sub 2}, CH{sub 4} or C{sub 3}H{sub 8} with air is investigated for both concave and convex curvature. To examine the effects of curvature on extinction, the critical fuel dilution ratios at extinction are measured at various stretch rates, initial mixture strengths and flame curvature for fuels diluted in N{sub 2}, He, Ar or CO{sub 2}. In addition, the onset conditions of the cellular instability are mapped as a function of stretch rates, initial mixture strengths, and flame curvature. For fuel mixtures with Lewis numbers much less than unity, such as H{sub 2}/N{sub 2}, concave flame curvature towards the fuel suppresses cellular instabilities. (author)

  6. Laser-induced breakdown spectroscopy measurement in methane and biodiesel flames using an ungated detector

    SciTech Connect (OSTI)

    Eseller, Kemal E.; Yueh, Fang Y.; Singh, Jagdish P

    2008-11-01T23:59:59.000Z

    Laser-induced breakdown spectroscopy (LIBS) has been applied to measure the equivalence ratio of CH4/air flames using gated detection. In this work, we have developed an ungated, miniature LIBS-based sensor for studying CH4/air and biodiesel flames. We have used this sensor to characterize the biodiesel flame. LIBS spectra of biodiesel flames were recorded with different ethanol concentrations in the biodiesel and also at different axial locations within the flame. The sensor performance was evaluated with a CH4/air flame. LIBS signals of N, O, and H from a CH4/air flame were used to determine the equivalence ratio. A linear relationship between the intensity ratio of H and O lines and the calculated equivalence ratio were obtained with this sensor.

  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. Modeling of combustion noise spectrum from turbulent premixed flames

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Modeling of combustion noise spectrum from turbulent premixed flames Y. Liu, A. P. Dowling, T. D, Nantes, France 2321 #12;Turbulent combustion processes generate sound radiation due to temporal changes, this temporal correlation and its role in the modeling of combustion noise spectrum are studied by analyzing

  9. Flame Synthesis of Carbon Nanotubes Using Low Calorific Value Gases

    SciTech Connect (OSTI)

    Jorge Camacho; Mahesh Subramanya; Ahsan R. Choudhuri

    2007-03-31T23:59:59.000Z

    Nanostructures formed in diffusion flames of pure fuels [CH{sub 4}, C{sub 3}H{sub 8}, and C{sub 2}H{sub 2}] at different fuel flow rates have been analyzed. Synthesis samples have been also collected from diffusion flames of various fuel blends [H{sub 2}-CH{sub 4}, H{sub 2}-CO, H{sub 2}-C{sub 3}H{sub 8}, H{sub 2}-C{sub 2}H{sub 2}] at different combustion conditions. SEM images of particulate samples collected from H{sub 2}-CH{sub 4} diffusion flames show formation of nanostructures. However, the formation of nanostructures only occurs at a narrow window of fuel compositions (< 10% H{sub 2} concentration in the mixture) and flow conditions (Jet Exit Reynolds number Re{sub j} = 200). At higher H{sub 2} concentration and flow velocity, formation of nanostructures diminishes and H{sub 2}-CH{sub 4} flames produce amorphous carbon and soot particles.

  10. Flame/Wall interactions : laminar study of unburnt HC formation

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    and desorption by oil film, deposits in combustion chamber, flame quenching, mixture and incomplete combustion for an important part to the sources of hydrocarbon (HC) emission in a combustion chamber. The aim of this work in gasoline engine. A skeletal mechanism (29 species and 48 reactions) mimicking iso-octane combustion is used

  11. Europium-doped yttrium silicate nanophosphors prepared by flame synthesis

    E-Print Network [OSTI]

    Bernhard, Stefan

    Europium-doped yttrium silicate nanophosphors prepared by flame synthesis Xiao Qin a,*, Yiguang Ju; accepted 7 November 2006 Available online 22 December 2006 Abstract Europium-doped yttrium silicate (Y2SiO5 properties 1. Introduction Yttrium silicate (Y2SiO5) is an important luminescent host material for various

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

    E-Print Network [OSTI]

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

    2014-06-26T23:59:59.000Z

    process and consumed in the subsequent high temperature oxidation. Formaldehyde LIF was used for autoignition of methane jets [6], methanol, ethanol and acetone spray jet flames [7,8], and diesel fuel [9-11] and n-heptane [11,12] in HCCI engines. Najm...

  13. Multiscale Simulation of Titania Nanoparticle Evolution in a Turbulent Flame

    E-Print Network [OSTI]

    Raman, Venkat

    numerous applications in drug delivery, catalysis, energy and semiconductors. Titanium dioxide (TiO2, The University of Texas, Austin, TX 78712, USA Abstract Titanium dioxide nanoparticles are manufactured in flame-based titanium dioxide synthesis are developed. A reduced chemistry mech- anism for gas-phase chemistry

  14. Structure of Partially Premixed Flames Using Detailed Chemistry Simulations

    E-Print Network [OSTI]

    Kluzek, Celine D.

    2010-10-12T23:59:59.000Z

    obtained at Sandia National Labs in 2001. The study is focused on axisymmetric laminar partially-premixed methane/air flames with varying premixture strength values of 1.8, 2.2, and 3.17. The combination of computational and experimental results is used...

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

    E-Print Network [OSTI]

    Kulatilaka, Waruna Dasal

    2002-01-01T23:59:59.000Z

    . The probe beam was tuned to the single-photon 486-nm n = 2 --> n = 4 resonance of the hydrogen atom by fundamental and frequency-doubled beams from a single 486-nm dye laser were used. The probe beam was linearly polarized entering the flame...

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

    E-Print Network [OSTI]

    Groth, Clinton P. T.

    LES of a Hydrogen-Enriched Lean Turbulent Premixed Flame Francisco E. Hern´andez-P´erez , Clinton the observed behaviour is examined. Hydrogen-hydrocarbon fuel blends appear to be a promising option to synergistically pave the way toward pure hydrogen-based combustion systems while alleviating green-house gas

  17. atomic absorption flame: Topics by E-print Network

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

    absorption flame First Page Previous Page 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Next Page Last Page Topic Index 1 Absorption properties of identical...

  18. Real Time Flame Monitoring of Gasifier and Injectors

    SciTech Connect (OSTI)

    Zelepouga, Serguei; Saveliev, Alexei

    2011-12-31T23:59:59.000Z

    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.

  19. Numerical assessment of stability criteria from disturbance energies in gaseous combustion

    E-Print Network [OSTI]

    Nicoud, Franck

    Numerical assessment of stability criteria from disturbance energies in gaseous combustion A, which corresponds to a ducted, laminar premixed propane-air flame, is used to assess the different terms a contribution from the unsteady heat flux-pressure correlation, allows a better agreement with the numerical

  20. ELG 5124: Virtual Environments, (Winter 2008) ELG 5124 Virtual Environments (Winter 2008)

    E-Print Network [OSTI]

    Petriu, Emil M.

    , human body modeling and animation. #12;ELG 5124: Virtual Environments, (Winter 2008) AnimationELG 5124: Virtual Environments, (Winter 2008) ELG 5124 Virtual Environments (Winter 2008) Tuesday% _______________________________________________ Calendar description Basic concepts. Virtual worlds. Hardware and software support. World modeling

  1. Soot microstructure in steady and flickering laminar methane/air diffusion flames

    SciTech Connect (OSTI)

    Zhang, J.; Megaridis, C.M. [Univ. of Illinois, Chicago, IL (United States). Dept. of Mechanical Engineering

    1998-03-01T23:59:59.000Z

    An experimental investigation is presented to identify the mechanisms responsible for the enhanced sooting behavior of strongly flickering methane/air jet diffusion flames when compared to their steady counterparts. The work extends the implementation of thermophoretic sampling in flickering, co-flow, laminar, diffusion flames. Acoustic forcing of the fuel flow rate is used to phase lock the periodic flame flicker close to the natural flicker frequency ({approximately} 10 Hz for a burner diameter of {approximately} 1 cm). Soot primary sizes, determined as functions of flame coordinates, indicate that the largest soot primary units in strongly flickering methane/air flames are larger by {approximately} 60% than those measured in steady flames with the same mean reactant flow rates. The primary particle size measurements, when combined with the soot volume fractions reported by other investigators, indicate that soot surface areas in the flickering flame are three to four times larger than those under steady conditions. These results, along with the fact that residence times in the flickering flame are twice as long as those in the steady flame, suggest that specific soot surface growth rates under unsteady combustion conditions can be similar or even lower than those in the corresponding steady flames. Finally, the number of densities of soot primaries in flickering flames are found to be higher by 30--50% than those in steady flames, thus suggesting stronger and/or extended soot inception mechanisms under flickering conditions. The combination of longer flow residence times and greater population of incipient soot particles in flickering flames appears to be primarily responsible for the higher sooting propensity of methane under laminar unsteady combustion conditions.

  2. Virtual Science Fair | Department of Energy

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

    Virtual Science Fair Virtual Science Fair The Bioenergy Technology Office (BETO) is hosting a national virtual science fair that engages 9th-12th grade students in learning about...

  3. Virtual stationary timed automata for mobile networks

    E-Print Network [OSTI]

    Nolte, Tina Ann, 1979-

    2009-01-01T23:59:59.000Z

    In this thesis, we formally define a programming abstraction for mobile networks called the Virtual Stationary Automata programming layer, consisting of real mobile clients, virtual timed I/O automata called virtual ...

  4. Expressive Autonomous Cinematography for Interactive Virtual Environments

    E-Print Network [OSTI]

    Tomlinson, Bill

    Expressive Autonomous Cinematography for Interactive Virtual Environments Bill Tomlinson Synthetic an automatic cinematography system for interactive virtual environments. This system controls a virtual camera this cinematography system with an ethologically-inspired structure of sensors, emotions, motivations, and action

  5. FLAME facility: The effect of obstacles and transverse venting on flame acceleration and transition on detonation for hydrogen-air mixtures at large scale

    SciTech Connect (OSTI)

    Sherman, M.P.; Tieszen, S.R.; Benedick, W.B.

    1989-04-01T23:59:59.000Z

    This report describes research on flame acceleration and deflagration-to-detonation transition (DDT) for hydrogen-air mixtures carried out in the FLAME facility, and describes its relevance to nuclear reactor safety. Flame acceleration and DDT can generate high peak pressures that may cause failure of containment. FLAME is a large rectangular channel 30.5 m long, 2.44 m high, and 1.83 m wide. It is closed on the ignition end and open on the far end. The three test variables were hydrogen mole fraction (12--30%), degree of transverse venting (by moving steel top plates---0%, 13%, and 50%), and the absence or presence of certain obstacles in the channel (zero or 33% blockage ratio). The most important variable was the hydrogen mole fraction. The presence of the obstacles tested greatly increased the flame speeds, overpressures, and tendency for DDT compared to similar tests without obstacles. Different obstacle configurations could have greater or lesser effects on flame acceleration and DDT. Large degrees of transverse venting reduced the flame speeds, overpressures, and possibility of DDT. For small degrees of transverse venting (13% top venting), the flame speeds and overpressures were higher than for no transverse venting with reactive mixtures (>18% H/sub 2/), but they were lower with leaner mixtures. The effect of the turbulence generated by the flow out the vents on increasing flame speed can be larger than the effect of venting gas out of the channel and hence reducing the overpressure. With no obstacles and 50% top venting, the flame speeds and overpressures were low, and there was no DDT. For all other cases, DDT was observed above some threshold hydrogen concentration. DDT was obtained at 15% H/sub 2/ with obstacles and no transverse venting. 67 refs., 62 figs.

  6. Fuel control for gas turbine with continuous pilot flame

    DOE Patents [OSTI]

    Swick, Robert M. (Indianapolis, IN)

    1983-01-01T23:59:59.000Z

    An improved fuel control for a gas turbine engine having a continuous pilot flame and a fuel distribution system including a pump drawing fuel from a source and supplying a line to the main fuel nozzle of the engine, the improvement being a control loop between the pump outlet and the pump inlet to bypass fuel, an electronically controlled throttle valve to restrict flow in the control loop when main nozzle demand exists and to permit substantially unrestricted flow without main nozzle demand, a minimum flow valve in the control loop downstream of the throttle valve to maintain a minimum pressure in the loop ahead of the flow valve, a branch tube from the pilot flame nozzle to the control loop between the throttle valve and the minimum flow valve, an orifice in the branch tube, and a feedback tube from the branch tube downstream of the orifice to the minimum flow valve, the minimum flow valve being operative to maintain a substantially constant pressure differential across the orifice to maintain constant fuel flow to the pilot flame nozzle.

  7. Fabrication of functional nanomaterials using flame assisted spray pyrolysis

    SciTech Connect (OSTI)

    Purwanto, Agus, E-mail: aguspur@uns.ac.id [Chemical Engineering Department, Faculty of Engineering, Sebelas Maret University, Surakarta 632112 (Indonesia)

    2014-02-24T23:59:59.000Z

    Flame assisted spray pyrolysis (FASP) is a class of synthesis method for nanomaterials fabrication. The ability to control nanomaterials characteristics and easy to be-scaled up are the main features of FASP. The crystallinity and particles size of the prepared nanomaterials can be easily controlled by variation of fuel flow rate. The precursor concentration, carrier gas flow rate, and carrier gas can be also used to control the prepared nanomaterials. Energy related nanomaterials preparation uses as the example case in FASP application. These material are yttrium aluminum garnet (YAG:Ce) and tungsten oxide (WO{sub 3}). It needs strategies to produce these materials into nano-sized order. YAG:Ce nanoparticles only can be synthesized by FASP using the urea addition. The decomposition of urea under high temperature of flame promotes the breakage of YAG:Ce particles into nanoparticles. In the preparation of WO{sub 3}, the high temperature flame can be used to gasify WO{sub 3} solid material. As a result, WO{sub 3} nanoparticles can be prepared easily. Generally, to produce nanoparticles via FASP method, the boiling point of the material is important to determine the strategy which will be used.

  8. 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

    2009-01-01T23:59:59.000Z

    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...

  9. The speciation and morphology of chromium oxide nanoparticles in a diffusion flame

    E-Print Network [OSTI]

    Guo, B; Kennedy, Ian M

    2004-01-01T23:59:59.000Z

    Shaffer et al. , 2001).Thermophoretic sampling was also usedwithin the flame. The thermophoretic sampling device wasbe discussed shortly. The thermophoretic drift velocity of

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

    E-Print Network [OSTI]

    Saxena, Priyank

    2007-01-01T23:59:59.000Z

    was used to vaporize ethanol fuel. The vaporizer wasmixture of the evaporated ethanol fuel and the nitrogen gas.premixed flames of ethanol and other fuels for comparison

  11. Numerical study of premixed twin edge flames in a counterflow field

    SciTech Connect (OSTI)

    Cho, Seong-Jin; Takita, Kenichi [Department of Aeronautics and Space Engineering, Tohoku University, Aramaki, Sendai 980-8579 (Japan)

    2006-01-01T23:59:59.000Z

    Characteristics of premixed edge flames established in a counterflow field with a stretch-rate gradient were numerically investigated by solving three-dimensional governing equations with detailed chemistry in the general curvilinear coordinates system. Local mole fractions of radicals, such as OH or CH, at the flame edge of a CH{sub 4}/air mixture were found to be larger than those in other parts of the flame. On the other hand, local mole fractions of radicals in the flame edge of a C{sub 3}H{sub 8}/air mixture were smaller than those in other parts. These numerical results agreed well with the experimental results of the present authors. Moreover, it was elucidated that two flame edges of twin counterflow flames did not merge at the edge even in the case of the CH{sub 4}/air mixture. The ratio of the local stretch rate at the flame edge to the extinction stretch rate for planar twin flames with the same equivalence ratio was 0.6 for the CH{sub 4}/air mixture and 0.7 for the C{sub 3}H{sub 8}/air mixture. These numerical results also agreed with results of the past experiments. Moreover, as for relatively low stretch-rate gradients, the stretch-rate gradient had no strong influence on the characteristics of the edge flames.

  12. 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

    2013-09-30T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Saxena, Priyank

    2007-01-01T23:59:59.000Z

    ethanol flames”, ASME TURBO EXPO 2006: Power for Land, Seaof GT2006, ASME Turbo Expo 2006: Power for Land, Sea and

  14. 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.

    2003-01-01T23:59:59.000Z

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

  15. 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.

    2004-01-01T23:59:59.000Z

    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 —

  16. Flame front disturbance induced by a weak pressure wave

    SciTech Connect (OSTI)

    Dobashi, Ritsu; Hirano, Toshisuke; Tsuruda, Takashi [Univ. of Tokyo (Japan)

    1994-12-31T23:59:59.000Z

    An experimental study has been conducted on the effect of unburned mixture properties on flame front disturbance induced by acceleration. Experiments were performed using a rectangular combustion chamber of 80 x 80 x 440 mm. The flame front disturbance was observed in two different directions by high-speed schlieren photography. Mixtures used are of three different concentrations (C = 0.8, 1.0, and 1.25) of methane/air and two different concentrations (C = 1.0 and 1.5) of propane/air. For the methane/air mixture of C = 1.0, experiments were performed at three different initial pressures (P{sub i} = 50, 70, and 101 kPa). The observed disturbance was of a very fine structure of circular spikes, which penetrated into the burned gas. The scales of disturbance were measured and indicated to be in the range of 1.7--4.0 mm. The circular spike shape is a typical structure induced by accelerating the flame front where the density changes steeply. However, the shape of the disturbance observed for a rich propane/air mixture was not of circular spikes but of a net of ridges. For the rich propane/air mixture, the effect by preferential diffusion was remarkable and the disturbance of a different structure was generated. For the methane/air mixtures, the scale was the smallest at C = 1.0 and larger at C = 0.8 and 1.25. The scale for the propane/air mixture of C = 1.0 was slightly larger than that in the methane/air mixture of C = 1.0. The scale became larger with the decrease of the initial pressure. The measure scales were compared with the preheat zone thicknesses of corresponding flames. It was shown that the scale is closely related with the flame thickness. The scale of disturbance is found to be about 15 times as large as the preheat zone thickness.

  17. 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]

    2013-01-01T23:59:59.000Z

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

  18. Designing a Virtual Manikin Animation Framework Aimed at Virtual Prototyping

    E-Print Network [OSTI]

    Rennuit, Antoine; Andriot, Claude; Guillaume, François; Chevassus, Nicolas; Chablat, Damien; Chedmail, Patrick

    2007-01-01T23:59:59.000Z

    In the industry, numerous commercial packages provide tools to introduce, and analyse human behaviour in the product's environment (for maintenance, ergonomics...), thanks to Virtual Humans. We will focus on control. Thanks to algorithms newly introduced in recent research papers, we think we can provide an implementation, which even widens, and simplifies the animation capacities of virtual manikins. In order to do so, we are going to express the industrial expectations as for Virtual Humans, without considering feasibility (not to bias the issue). The second part will show that no commercial application provides the tools that perfectly meet the needs. Thus we propose a new animation framework that better answers the problem. Our contribution is the integration - driven by need ~ of available new scientific techniques to animate Virtual Humans, in a new control scheme that better answers industrial expectations.

  19. 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)

    2009-08-15T23:59:59.000Z

    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)

  20. Soot aerosol properties in laminar soot-emitting microgravity nonpremixed flames

    SciTech Connect (OSTI)

    Konsur, B.; Megaridis, C.M.; Griffin, D.W.

    1999-09-01T23:59:59.000Z

    The spatial distributions and morphological properties of the soot aerosol are examined experimentally in a series of 0-g laminar gas-jet nonpremixed flames. The methodology deploys round jet diffusion flames of nitrogen-diluted acetylene fuel burning in quiescent air at atmospheric pressure. Full-field laser-light extinction is utilized to determine transient soot spatial distributions within the flames. Thermophoretic sampling is employed in conjunction with transmission electron microscopy to define soot microstructure within the soot-emitting 0-g flames. The microgravity tests indicate that the 0-g flames attain a quasi-steady state roughly 0.7 s after ignition, and sustain their annular structure even beyond their luminous flame tip. The measured peak soot volume fractions show a complex dependence on burner exit conditions, and decrease in a nonlinear fashion with decreasing characteristic flow residence times. Fuel preheat by {approximately}140K appears to accelerate the formation of soot near the flame axis via enhanced field pyrolysis rates. The increased soot presence caused by the elevated fuel injection temperatures triggers higher flame radiative losses, which may account for the premature suppression of soot growth observed along the annular region of preheated-fuel flames. Electron micrographs of soot aggregates collected in 0-g reveal the presence of soot precursor particles near the symmetry axis at midflame height. The observations also verify that soot primary particle sizes are nearly uniform among aggregates present at the same flame location, but vary considerably with radius at a fixed distance from the burner. The maximum primary size in 0-g is found to be by 40% larger than in 1-g, under the same burner exit conditions. Estimates of the number concentration of primary particles and surface area of soot particulate phase per unit volume of the combustion gases are also made for selected in-flame locations.

  1. 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. [Department of Power Engineering, Jadavpur University, Salt Lake Campus, Kolkata 700098 (India)

    2009-02-15T23:59:59.000Z

    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)

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

    E-Print Network [OSTI]

    Mukundan, Mallika

    2009-05-15T23:59:59.000Z

    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. LASER STABILIZATION FOR NEAR ZERO NO{sub x} GAS TURBINE COMBUSTION SYSTEMS

    SciTech Connect (OSTI)

    Vivek Khanna

    2002-09-30T23:59:59.000Z

    Historically, the development of new industrial gas turbines has been primarily driven by the intent to achieve higher efficiency, lower operating costs and lower emissions. Higher efficiency and lower cost is obtained through higher turbine operating temperatures, while reduction in emissions is obtained by extending the lean operating limit of the combustor. However reduction in the lean stability limit of operation is limited greatly by the chemistry of the combustion process and by the occurrence of thermo-acoustic instabilities. Solar Turbines, CFD Research Corporation, and Los Alamos National Laboratory have teamed to advance the technology associated with laser-assisted ignition and flame stabilization, to a level where it could be incorporated onto a gas turbine combustor. The system being developed is expected to enhance the lean stability limit of the swirl stabilized combustion process and assist in reducing combustion oscillations. Such a system has the potential to allow operation at the ultra-lean conditions needed to achieve NO{sub x} emissions below 5 ppm without the need of exhaust treatment or catalytic technologies. The research effort was focused on analytically modeling laser-assisted flame stabilization using advanced CFD techniques, and experimentally demonstrating the technology, using a solid-state laser and low-cost durable optics. A pulsed laser beam was used to generate a plasma pool at strategic locations within the combustor flow field such that the energy from the plasma became an ignition source and helped maintain a flame at ultra lean operating conditions. The periodic plasma generation and decay was used to nullify the fluctuations in the heat release from the flame itself, thus decoupling the heat release from the combustor acoustics and effectively reducing the combustion oscillations. The program was built on an existing technology base and includes: extending LANL's existing laser stabilization experience to a sub-scale combustor rig, performing and validating CFD predictions, and ultimately conducting a full system demonstration in a multi-injector combustion system at Solar Turbines.

  4. Virtual gap dielectric wall accelerator

    DOE Patents [OSTI]

    Caporaso, George James; Chen, Yu-Jiuan; Nelson, Scott; Sullivan, Jim; Hawkins, Steven A

    2013-11-05T23:59:59.000Z

    A virtual, moving accelerating gap is formed along an insulating tube in a dielectric wall accelerator (DWA) by locally controlling the conductivity of the tube. Localized voltage concentration is thus achieved by sequential activation of a variable resistive tube or stalk down the axis of an inductive voltage adder, producing a "virtual" traveling wave along the tube. The tube conductivity can be controlled at a desired location, which can be moved at a desired rate, by light illumination, or by photoconductive switches, or by other means. As a result, an impressed voltage along the tube appears predominantly over a local region, the virtual gap. By making the length of the tube large in comparison to the virtual gap length, the effective gain of the accelerator can be made very large.

  5. Weak Deeply Virtual Compton Scattering

    E-Print Network [OSTI]

    A. Psaker; W. Melnitchouk; A. V. Radyushkin

    2006-12-21T23:59:59.000Z

    We extend the analysis of the deeply virtual Compton scattering process to the weak interaction sector in the generalized Bjorken limit. The virtual Compton scattering amplitudes for the weak neutral and charged currents are calculated at the leading twist within the framework of the nonlocal light-cone expansion via coordinate space QCD string operators. Using a simple model, we estimate cross sections for neutrino scattering off the nucleon, relevant for future high intensity neutrino beam facilities.

  6. Weak Deeply Virtual Compton Scattering

    SciTech Connect (OSTI)

    Ales Psaker; Wolodymyr Melnitchouk; Anatoly Radyushkin

    2007-03-01T23:59:59.000Z

    We extend the analysis of the deeply virtual Compton scattering process to the weak interaction sector in the generalized Bjorken limit. The virtual Compton scattering amplitudes for the weak neutral and charged currents are calculated at the leading twist within the framework of the nonlocal light-cone expansion via coordinate space QCD string operators. Using a simple model, we estimate cross sections for neutrino scattering off the nucleon, relevant for future high intensity neutrino beam facilities.

  7. Study on premixed combustion in cylindrical micro combustors: Transient flame behavior and wall heat flux

    SciTech Connect (OSTI)

    Li, J.; Chou, S.K.; Huang, G.; Yang, W.M. [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576 (Singapore); Li, Z.W. [SSLS, National University of Singapore, 5 Research Link, Singapore 117603 (Singapore)

    2009-04-15T23:59:59.000Z

    The micro combustor is a key component of the micro thermophotovoltaic (TPV) system. Improving the wall temperature of the micro combustor is an effective way to elevate the system efficiency. An experimental study on the wall temperature and radiation heat flux of a series of cylindrical micro combustors (with a backward-facing step) was carried out. For the micro combustors with d = 2 mm, the regime of successful ignition (under the cold wall condition) was identified for different combustor lengths. Acoustic emission was detected for some cases and the emitted sound was recorded and analyzed. Under the steady-state condition, the effects of the combustor diameter (d), combustor length (L), flow velocity (u{sub 0}) and fuel-air equivalence ratio ({phi}) on the wall temperature distribution were investigated by measuring the detailed wall temperature profiles. In the case that the micro combustor is working as an emitter, the optimum efficiency was found at {phi} {approx} 0.8, independent of the combustor dimensions (d and L) and the flow velocity. Under the experimental conditions employed in the present study, the positions of the peak wall temperature were found to be about 8-11 mm and 4-6 mm from the step for the d = 3 mm and d = 2 mm micro combustors, respectively, which are 8-11 and 8-12 times of their respective step heights. This result suggests that the backward-facing step employed in the combustor design is effective in stabilizing the flame position. (author)

  8. Soot formation and temperature field structure in co-flow laminar methaneair diffusion flames

    E-Print Network [OSTI]

    Gülder, Ömer L.

    at higher pressures mean that the thermal diffusion from the hot regions of the flame towards the flame of the spread of unwanted fires. Soot radiation is the major heat load on combustor components causing mainte gas turbine combustors operate at elevated pressures, our understanding of the effects of pressure

  9. 45 (2008-5) Thermal Effect of Wall on Micro Premixed Flame in Quartz Channels

    E-Print Network [OSTI]

    Kasagi, Nobuhide

    E131 45 (2008-5) 225 Thermal Effect of Wall on Micro Premixed Flame in Quartz Channels * Yong flame propagation and quenching in three quartz combustors with chamber depth of 0.7 mm, 1.0 mm and 1 to meet the requirement. Hydrocarbon-fueled micro combustor is of great interest in portable power

  10. Growth of diamond films using an enclosed methyl-acetylene and propadiene combustion flame

    E-Print Network [OSTI]

    Dandy, David

    1 Growth of diamond films using an enclosed methyl-acetylene and propadiene combustion flame K Abstract Diamond growth in low pressure combustion flames was studied using a safer, more economical and chemical kinetic time scales in the combustion reactor. 1 Present Address: 3M Corporation, Bldg. 60-1N-01

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

    SciTech Connect (OSTI)

    Torii, Shuichi; Yano, Toshiaki; Tsuchino, Fumihiro

    1999-07-01T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Aggarwal, Suresh K.

    for outwardly propagating spherical flames burning a mixture of natural gas and hydrogen. © 2008 The Combustion enrichment on the propagation characteristics of CH4­air triple flames Alejandro M. Briones a , Suresh K 22 February 2008 Available online 7 April 2008 Abstract The effects of H2 enrichment

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

    E-Print Network [OSTI]

    Gülder, Ömer L.

    2006-01-01T23:59:59.000Z

    and temperature field structure in laminar propane­air diffusion flames at elevated pressures Décio S. Bento and the structure of the temperature field was studied in coflow propane­air laminar diffusion flames over to within 30% and both methods exhibited similar trends in the spatial distribution of soot concentration

  15. 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

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

    E-Print Network [OSTI]

    Gülder, �mer L.

    . 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 into account. Radiation heat transfer from CO2, CO, H2O, and soot was calculated using the discrete- ordinates

  17. Virtual environment tactile system

    DOE Patents [OSTI]

    Renzi, Ronald (90 Arroyo Seco Way, Tracy, San Joaquin County, CA 95376)

    1996-01-01T23:59:59.000Z

    A method for providing a realistic sense of touch in virtual reality by means of programmable actuator assemblies is disclosed. Each tactile actuator assembly consists of a number of individual actuators whose movement is controlled by a computer and associated drive electronics. When an actuator is energized, the rare earth magnet and the associated contactor, incorporated within the actuator, are set in motion by the opposing electromagnetic field of a surrounding coil. The magnet pushes the contactor forward to contact the skin resulting in the sensation of touch. When the electromagnetic field is turned off, the rare earth magnet and the contactor return to their neutral positions due to the magnetic equilibrium caused by the interaction with the ferrous outer sleeve. The small size and flexible nature of the actuator assemblies permit incorporation into a glove, boot or body suit. The actuator has additional applications, such as, for example, as an accelerometer, an actuator for precisely controlled actuations or to simulate the sensation of braille letters.

  18. Virtual environment tactile system

    DOE Patents [OSTI]

    Renzi, R.

    1996-12-10T23:59:59.000Z

    A method for providing a realistic sense of touch in virtual reality by means of programmable actuator assemblies is disclosed. Each tactile actuator assembly consists of a number of individual actuators whose movement is controlled by a computer and associated drive electronics. When an actuator is energized, the rare earth magnet and the associated contactor, incorporated within the actuator, are set in motion by the opposing electromagnetic field of a surrounding coil. The magnet pushes the contactor forward to contact the skin resulting in the sensation of touch. When the electromagnetic field is turned off, the rare earth magnet and the contactor return to their neutral positions due to the magnetic equilibrium caused by the interaction with the ferrous outer sleeve. The small size and flexible nature of the actuator assemblies permit incorporation into a glove, boot or body suit. The actuator has additional applications, such as, for example, as an accelerometer, an actuator for precisely controlled actuations or to simulate the sensation of braille letters. 28 figs.

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

    E-Print Network [OSTI]

    Geddes, Cameron Guy Robinson

    A New Type of Steady and Stable, Laminar, Premixed Flame in Ultra-Lean, Hydrogen-Air Combustion in the development of combustion science. Several aspects of these two-dimensional flame cells are identified for premixed combustion when the other types of idealized flames are inapplicable. 1 #12;Nomenclature fuel

  20. 1 Copyright 2007 by ASME Flame Structure and Stabilization Mechanisms in a

    E-Print Network [OSTI]

    Seitzman, Jerry M.

    Reverse Flow Combustor Mohan K. Bobba, Priya Gopalakrishnan, Karthik Periagaram and Jerry M. Seitzman A novel combustor design, referred to as a Stagnation Point Reverse Flow (SPRF) combustor, was recently combustor is able to operate stably at very lean fuel-air mixtures with low NOx emissions. The reverse flow

  1. Dynamic stability, blowoff, and flame characteristics of oxy-fuel combustion

    E-Print Network [OSTI]

    Shroll, Andrew Philip

    2011-01-01T23:59:59.000Z

    Oxy-fuel combustion is a promising technology to implement carbon capture and sequestration for energy conversion to electricity in power plants that burn fossil fuels. In oxy-fuel combustion, air separation is used to ...

  2. Flame-Retardant Epoxy Resin Nanocomposites Reinforced with Polyaniline-Stabilized Silica Nanoparticles

    E-Print Network [OSTI]

    Guo, John Zhanhu

    Department of Chemical Engineering, Lamar University, Beaumont, Texas 77710, United States School # Department of Chemistry and Biochemistry, Lamar University, Beaumont, Texas 77710, United States Materials

  3. American Institute of Aeronautics and Astronautics Flame Stabilization and Mixing Studies

    E-Print Network [OSTI]

    Seitzman, Jerry M.

    combustion and mixing characteristics are investigated with a variety of imaging diagnostics: simultaneous OH PLIF and chemiluminescence (heat release) measurements, and laser scattering of oil droplets seeded on lean premixed or partially premixed combustion. Ensuring that combustion occurs at locally lean

  4. Dimpled/grooved face on a fuel injection nozzle body for flame stabilization and related method

    DOE Patents [OSTI]

    Uhm, Jong Ho; Johnson, Thomas Edward; Kim, Kwanwoo; Zuo, Baifang

    2013-08-20T23:59:59.000Z

    A fuel injection head for a fuel nozzle used in a gas turbine combustor includes a substantially hollow body formed with an upstream end face, a downstream end face and a peripheral wall extending therebetween. A plurality of pre-mix tubes or passages extend axially through the hollow body with inlets at the upstream end face and outlets at the downstream end face. An exterior surface of the downstream end face is formed with three-dimensional surface features that increase a total surface area of the exterior surface as compared to a substantially flat, planar downstream end face.

  5. Calculations of a Turbulent Bluff-Body Stabilized Flame , S. B. Pope and D. A. Caughey

    E-Print Network [OSTI]

    methodologies, the treatment of chemical reaction is based on mixture fraction. Present day mixture fraction a relatively simple skeletal chemical mechanism. Since the augmented reduced mechanism for methane (ARM) [12. The in situ adaptive tabulation (ISAT) method is used to implement methane chemistry using an Augmented

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

    E-Print Network [OSTI]

    Yanez, J; Bykov, V

    2012-01-01T23:59:59.000Z

    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 ...

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

    SciTech Connect (OSTI)

    Nagase, K.; Funatsu, K.

    1988-01-01T23:59:59.000Z

    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.

  8. 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

    2015-01-01T23:59:59.000Z

    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...

  9. Virtual Oxygen Sensor for Innovative NOx and PM Emission Control...

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

    Virtual Oxygen Sensor for Innovative NOx and PM Emission Control Technologies Virtual Oxygen Sensor for Innovative NOx and PM Emission Control Technologies A virtual O2 sensor for...

  10. Pocket formation and the flame surface density equation

    SciTech Connect (OSTI)

    Kollman, W. [Univ. of California, Davis, CA (United States); Chen, J.H. [Sandia National Labs., Livermore, CA (United States). Combustion Research Facility

    1998-03-01T23:59:59.000Z

    The occurrence and properties of singularities in the equation for the surface density function {sigma} {triple_bond}{vert_bar}{del}{Phi}{vert_bar} are analyzed analytically and numerically using data from two dimensional direct numerical simulation (DNS) of pocket formation in a premixed methane-air flame. The various stages and the relevant time scales associated with pocket formation were determined in a previous study. It was found that isolated pockets form if and only if a nondegenerate critical point of a saddle point type appears. The appearance of a singularity in the isoline representing the flame front may have implications to modeling of the terms in the surface density function (sdf) approach during such transient events as pocket formation. The sink and source terms in sdf are evaluated in the neighborhood of a critical point using DNS data during pocket formation, and an analytic representation of a scalar in the vicinity of the critical point which allows for the computation of all kinematic properties. The analytic and computational results show that the normal restoration and dissipation terms in the sdf become singular at the critical point when the pocket emerges. Furthermore, the analytic results show that the singularities exactly cancel, and therefore, the main conclusion is that it is unnecessary to model the singular behavior of these terms at critical points. However, closure of their sum is recommended.

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

    SciTech Connect (OSTI)

    Wang, Hai (University of Southern California, Los Angeles, CA); Kook, Sanghoon; Doom, Jeffrey; Oefelein, Joseph Charles; Zhang, Jiayao; Shaddix, Christopher R.; Schefer, Robert W.; Pickett, Lyle M.

    2010-10-01T23:59:59.000Z

    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.

  12. Stabilizer Formalism for Operator Quantum Error Correction

    E-Print Network [OSTI]

    Poulin, D

    2005-01-01T23:59:59.000Z

    Operator quantum error correction is a recently developed theory that provides a generalized framework for active error correction and passive error avoiding schemes. In this paper, we describe these codes in the language of the stabilizer formalism of standard quantum error correction theory. This is achieved by adding a "gauge" group to the standard stabilizer definition of a code. Gauge transformations leave the encoded information unchanged; their effect is absorbed by virtual gauge qubits that do not carry useful information. We illustrate the construction by identifying a gauge symmetry in Shor's 9-qubit code that allows us to remove 3 of its 8 stabilizer generators, leading to a simpler decoding procedure without affecting its essential properties. This opens the path to possible improvement of the error threshold of fault tolerant quantum computing. We also derive a modified Hamming bound that applies to all stabilizer codes, including degenerate ones.

  13. Numerical study of the direct pressure effect of acoustic waves in planar premixed flames

    SciTech Connect (OSTI)

    Schmidt, H. [BTU Cottbus, Siemens-Halske-Ring 14, D-03046 Cottbus (Germany); Jimenez, C. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Avenida Complutense, 22, 28040 Madrid (Spain)

    2010-08-15T23:59:59.000Z

    Recently the unsteady response of 1-D premixed flames to acoustic pressure waves for the range of frequencies below and above the inverse of the flame transit time was investigated experimentally using OH chemiluminescence Wangher (2008). They compared the frequency dependence of the measured response to the prediction of an analytical model proposed by Clavin et al. (1990), derived from the standard flame model (one-step Arrhenius kinetics) and to a similar model proposed by McIntosh (1991). Discrepancies between the experimental results and the model led to the conclusion that the standard model does not provide an adequate description of the unsteady response of real flames and that it is necessary to investigate more realistic chemical models. Here we follow exactly this suggestion and perform numerical studies of the response of lean methane flames using different reaction mechanisms. We find that the global flame response obtained with both detailed chemistry (GRI3.0) and a reduced multi-step model by Peters (1996) lies slightly above the predictions of the analytical model, but is close to experimental results. We additionally used an irreversible one-step Arrhenius reaction model and show the effect of the pressure dependence of the global reaction rate in the flame response. Our results suggest first that the current models have to be extended to capture the amplitude and phase results of the detailed mechanisms, and second that the correlation between the heat release and the measured OH* chemiluminescence should be studied deeper. (author)

  14. Sensor and model integration for the rapid prediction of concurrent flow flame spread 

    E-Print Network [OSTI]

    Cowlard, Adam

    Fire Safety Engineering is required at every stage in the life cycle of modern-day buildings. Fire safety design, detection and suppression, and emergency response are all vital components of Structural Fire Safety but are usually perceived...Issues of accuracy aside, these models demand heavy resources and computational time periods that are far greater than the time associated with the processes being simulated. To be of use to emergency responders, the output would need to be produced faster than the event itself with lead time to enable planning of an intervention strategy. Therefore in isolation, model output is not robust or fast enough to be implemented in an emergency response scenario. The concept of super-real time predictions steered by measurements is studied in the simple yet meaningful scenario of concurrent flow flame spread. Experiments have been conducted with PMMA slabs to feed sensor data into a simple analytical model. Numerous sensing techniques have been adapted to feed a simple algebraic expression from the literature linking flame spread, flame characteristics and pyrolysis evolution in order to model upward flame spread. The measurements are continuously fed to the computations so that projections of the flame spread velocity and flame characteristics can be established at each instant in time, ahead of the real flame. It was observed that as the input parameters in the analytical models were optimised to the scenario, rapid convergence between the evolving experiment and the predictions was attained....

  15. Technical Documentation for System Center 2012 Virtual Machine

    E-Print Network [OSTI]

    Hunt, Galen

    #12; Technical Documentation for System Center 2012 ­ Virtual Machine Manager VMM Information Experience Team Summary: Virtual Machine Manager (VMM) is a management solution for the virtualized datacenter, enabling you to configure and manage your virtualization host, networking, and storage

  16. Developing a Conceptual Model of Virtual Organizations for Citizen Science

    E-Print Network [OSTI]

    Crowston, Kevin

    Developing a Conceptual Model of Virtual Organizations for Citizen Science Andrea Wiggins Syracuse-oriented conceptual model of scientific knowledge production through citizen science virtual organizations. Citizen: conceptual models, virtual organizations, citizen science, cyberinfrastructure, massive virtual

  17. Soot volume fraction and temperature measurements in laminar nonpremixed flames using thermocouples

    SciTech Connect (OSTI)

    Mcenally, C.S.; Koeylue, U.O.; Pfefferle, L.D.; Rosner, D.E. [Yale Univ., New Haven, CT (United States)] [Yale Univ., New Haven, CT (United States)

    1997-06-01T23:59:59.000Z

    Thermocouple particle densitometry (TPD), a new method for measuring absolute soot volume fraction in flames which was suggested by Eisner and Rosner, has been successfully implemented in several laminar nonpremixed flames. This diagnostic relies on measuring the junction temperature history of a thermocouple rapidly inserted into a soot-containing flame region, then optimizing the fit between this history and one calculated from the principles of thermophoretic mass transfer. The TPD method is very simple to implement experimentally, yields spatially resolved volume fractions directly, can easily measure small volume fractions, and does not depend on the prevailing soot particle size, morphology, or optical characteristics. In a series of methane and ethylene counterflow flames whose soot volume fractions varied by more than an order of magnitude, the TPD results agreed to within experimental error with the authors own laser extinction measurements. In axisymmetric methane and ethylene co-flowing flames, the shape of TPD profiles agreed well with published laser extinction measurements, but the TPD concentrations were significantly larger in the early regions of the ethylene flame and throughout the methane flame; these discrepancies are probably attributable to visible light-transparent particles that are detectable with TPD but not with laser extinction. The TPD method is not applicable to the upper regions of these co-flowing flames since OH concentrations there suffice to rapidly oxidize any soot particles that deposit. Gas temperatures were obtained simultaneously with volume fraction by averaging the junction temperature history shortly after insertion. The error in these temperatures due to soot deposition-imposed changes in the junction diameter and emissivity were assessed and found to be moderate, e.g., less than 60 K near the centerline of the ethylene coflowing flame where the volume fraction was 6 ppm and the gas temperature was 1,550 K.

  18. 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. [Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong (China)

    2006-01-01T23:59:59.000Z

    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.

  19. Virtual Education in Kansas: 1998-2014

    E-Print Network [OSTI]

    Adams, Christina Marie

    2014-08-31T23:59:59.000Z

    K-12 virtual education is a growing trend in American education. Virtual education is defined as K-12 online learning experiences led by district-affiliated teachers as part of a structured public school learning program ...

  20. The DOE Virtual University (DVU) Icon

    Broader source: Energy.gov [DOE]

     The Office of Learning & Workforce Development launched a desktop icon for its virtual university.  The DOE Virtual University (DVU) icon is on most of the DOE desktops (most of HQ, except EIA...

  1. Virtual Reality to Improve Remote Control in Presence of Delays

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    or domotics. I. VIRTUAL REALITY AND REMOTE CONTROL One of the aims of virtual reality is to reproduce real

  2. 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)

    2014-10-15T23:59:59.000Z

    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.

  3. 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)

    2010-11-15T23:59:59.000Z

    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)

  4. VIRTUAL TRAINING CENTRE FOR SHOE DESIGN: A SAMPLE VIRTUAL TRAINING ENVIRONMENT

    E-Print Network [OSTI]

    Aristomenis, Antoniadis

    VIRTUAL TRAINING CENTRE FOR SHOE DESIGN: A SAMPLE VIRTUAL TRAINING ENVIRONMENT Aura Mihai1 , Mehmet@tex.tuiasi.ro Abstract It is a fact that virtual training has become a key issue in training. There are numerous virtual learning and training environments and, in parallel with this, there are various approaches and tools

  5. The CloudNets Network Virtualization Architecture

    E-Print Network [OSTI]

    Schmid, Stefan

    Nets Network Virtualization Architecture Johannes Grassler jgrassler@inet.tu-berlin.de 05. Februar, 2014 Johannes Grassler jgrassler@inet.tu-berlin.de The CloudNets Network Virtualization Architecture #12;..... . .... . .... . ..... . .... . .... . .... . ..... . .... . .... . .... . ..... . .... . .... . .... . ..... . .... . ..... . .... . .... . Johannes Grassler jgrassler@inet.tu-berlin.de The CloudNets Network Virtualization Architecture #12

  6. Information in Virtual Spaces Susanne Riehemann

    E-Print Network [OSTI]

    Zalta, Edward N.

    as a result of developments in immersive interactive virtual 3D spaces, geographic information systems with these visualizations and by studying automatic verbalization of virtual events and automatic creation of virtual events that the user has control over viewpoints and can manipulate data or a

  7. A virtual substitution of Brouwer choice sequence

    E-Print Network [OSTI]

    Klaus Lange

    2009-08-24T23:59:59.000Z

    Step by step a substitution of the well known Brouwer choice sequence will be constructed. It begins with an establishing of quasi alternating prime number series followed by a construction of a virtual sequence in sense of the virtual set definition. The last step gives reasons for why this virtual sequence substitutes the choice sequence created by L. E. J. Brouwer.

  8. Pdf modeling of turbulent nonpremixed methane jet flames

    SciTech Connect (OSTI)

    Chen, J.Y.; Kollmann, W.; Dibble, R.W. (Sandia National Labs., Livermore, CA (USA). Combustion Research Faclity)

    1989-01-01T23:59:59.000Z

    An expanded model of turbulent nonpremixed combustion is presented. In the model, the scalar mixing and reactions are described by a probability density function (pdf) submodel capable of handling five scalars, while the turbulent velocity field is described by a second-order moment closure. Two plausible chemical reaction models are considered: a five-scalar, four-step, reduced reaction mechanism, and a four-scalar constrained equilibrium model. Detailed comparisons of model predictions with laser Raman experimental dat provide a valuable evaluation of the model's ability in predicting nonequilibrium chemistry in turbulent nonpremixed flames. Overall, the model fails to predict greater departure from chemical equilibrium as mixing rates are increased. Interestingly, this failure is not due to the chemical model, both of which perform satisfactorily. Instead, the failure to predict greater departure from chemical equilibrium is a subtle artifact of the current Monte Carlo simulation of turbulent mixing and chemical reaction.

  9. The ignition of thermonuclear flames in Type Ia supernovae

    E-Print Network [OSTI]

    L. Iapichino; M. Brüggen; W. Hillebrandt; J. C. Niemeyer

    2005-12-12T23:59:59.000Z

    In the framework of the Chandrasekhar-mass deflagration model for Type Ia supernovae (SNe Ia), a persisting free parameter is the initial morphology of the flame front, which is linked to the ignition process in the progenitor white dwarf. Previous analytical models indicate that the thermal runaway is driven by temperature perturbations (''bubbles'') that develop in the white dwarf's convective core. In order to probe the conditions at ignition (diameters, temperatures and evolutionary timescales), we have performed hydrodynamical 2D simulations of buoyant bubbles in white dwarf interiors. Our results show that fragmentation occurring during the bubble rise affects the outcome of the bubble evolution. Possible implications for the ignition process of SNe Ia are discussed.

  10. The ignition of thermonuclear flames in Type Ia supernovae

    E-Print Network [OSTI]

    Iapichino, L; Hillebrandt, W; Niemeyer, J C

    2005-01-01T23:59:59.000Z

    In the framework of the Chandrasekhar-mass deflagration model for Type Ia supernovae (SNe Ia), a persisting free parameter is the initial morphology of the flame front, which is linked to the ignition process in the progenitor white dwarf. Previous analytical models indicate that the thermal runaway is driven by temperature perturbations (''bubbles'') that develop in the white dwarf's convective core. In order to probe the conditions at ignition (diameters, temperatures and evolutionary timescales), we have performed hydrodynamical 2D simulations of buoyant bubbles in white dwarf interiors. Our results show that fragmentation occurring during the bubble rise affects the outcome of the bubble evolution. Possible implications for the ignition process of SNe Ia are discussed.

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

    SciTech Connect (OSTI)

    Hansen, Nils

    2013-02-12T23:59:59.000Z

    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.

  12. Virtual Control Systems Environment (VCSE)

    SciTech Connect (OSTI)

    Atkins, Will

    2012-10-08T23:59:59.000Z

    Will Atkins, a Sandia National Laboratories computer engineer discusses cybersecurity research work for process control systems. Will explains his work on the Virtual Control Systems Environment project to develop a modeling and simulation framework of the U.S. electric grid in order to study and mitigate possible cyberattacks on infrastructure.

  13. Toward Virtual Actors Maciej Kalisiak

    E-Print Network [OSTI]

    Toronto, University of

    yet another set of demands. One of the key objects being animated are human or human-like characters for storytelling and drama, natural-looking human animation has been a long-sought goal. Although our present. The advent of virtual actors would make computer animation accessible to a much larger user base, bringing

  14. Virtual Control Systems Environment (VCSE)

    ScienceCinema (OSTI)

    Atkins, Will

    2014-02-26T23:59:59.000Z

    Will Atkins, a Sandia National Laboratories computer engineer discusses cybersecurity research work for process control systems. Will explains his work on the Virtual Control Systems Environment project to develop a modeling and simulation framework of the U.S. electric grid in order to study and mitigate possible cyberattacks on infrastructure.

  15. Stochastic algorithms for the analysis of numerical flame simulations

    SciTech Connect (OSTI)

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

    2004-04-26T23:59:59.000Z

    Recent progress in simulation methodologies and high-performance parallel computers have made it is possible to perform detailed simulations of multidimensional reacting flow phenomena using comprehensive kinetics mechanisms. As simulations become larger and more complex, it becomes increasingly difficult to extract useful information from the numerical solution, particularly regarding the interactions of the chemical reaction and diffusion processes. In this paper we present a new diagnostic tool for analysis of numerical simulations of reacting flow. Our approach is based on recasting an Eulerian flow solution in a Lagrangian frame. Unlike a conventional Lagrangian view point that follows the evolution of a volume of the fluid, we instead follow specific chemical elements, e.g., carbon, nitrogen, etc., as they move through the system . From this perspective an ''atom'' is part of some molecule of a species that is transported through the domain by advection and diffusion. Reactions cause the atom to shift from one chemical host species to another and the subsequent transport of the atom is given by the movement of the new species. We represent these processes using a stochastic particle formulation that treats advection deterministically and models diffusion and chemistry as stochastic processes. In this paper, we discuss the numerical issues in detail and demonstrate that an ensemble of stochastic trajectories can accurately capture key features of the continuum solution. The capabilities of this diagnostic are then demonstrated by applications to study the modulation of carbon chemistry during a vortex-flame interaction, and the role of cyano chemistry in rm NO{sub x} production for a steady diffusion flame.

  16. Transportation planning: A virtual reality

    SciTech Connect (OSTI)

    Bradley, J. [Johnson Controls, International (United States); Hefele, J.; Dolin, R.M. [Los Alamos National Lab., NM (United States)

    1994-07-01T23:59:59.000Z

    An important factor in the development of any base technology is generating it in such a way that these technologies will continue to be useful through systems upgrades and implementation philosophy metamorphoses. Base technologies of traffic engineering including transportation modeling, traffic impact forecasting, traffic operation management, emergency situation routing and re-routing, and signal systems optimization should all be designed with the future in mind. Advanced Traffic Engineering topics, such as Intelligent Vehicle Highway Systems, are designed with advanced engineering concepts such as rules-based design and artificial intelligence. All aspects of development of base technologies must include Total Quality Engineering as the primary factor in order to succeed. This philosophy for development of base technologies for the County of Los Alamos is being developed leveraging the resources of the Center for Advanced Engineering Technology (CAET) at the Los Alamos National Laboratory. The mission of the CAET is to develop next-generation engineering technology that supports the Los Alamos National Laboratory`s mission and to transfer that technology to industry and academia. The CAET`s goal is to promote industrial, academic, and government interactions in diverse areas of engineering technology, such as, design, analysis, manufacturing, virtual enterprise, robotics, telepresence, rapid prototyping, and virtual environment technology. The Center is expanding, enhancing, and increasing core competencies at the Los Alamos National Laboratory. The CAET has three major thrust areas: development of base technologies, virtual environment technology applications, and educational outreach and training. Virtual environment technology immerses a user in a nonexistent or augmented environment for research or training purposes. Virtual environment technology illustrates the axiom, ``The best way to learn is by doing.``

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

    E-Print Network [OSTI]

    Laufer, Galina 1985-

    2012-10-23T23:59:59.000Z

    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...

  18. Acoustic Modes in Combustors with Complex Impedances and Multidimensional Active Flames

    E-Print Network [OSTI]

    Nicoud, Franck

    Acoustic Modes in Combustors with Complex Impedances and Multidimensional Active Flames F. Nicoud for computing the thermoacoustic modes in combustors. In the case of a nonisothermal reacting medium, the wave

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

    DOE Patents [OSTI]

    Kong, Peter C

    2013-11-26T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Gülder, �mer L.

    velocity pro- file as the gases leave the foam elements. Fig. 1 shows the details of the experimental performed pre- viously with methane [1] and propane [2] diffusion flames at elevated pressures. A constant

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

    E-Print Network [OSTI]

    Laufer, Galina 1985-

    2012-10-23T23:59:59.000Z

    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...

  2. Curl Flame Fractal Rib cage and neck of a Cretaceous plesiosaur (elasmosaur)

    E-Print Network [OSTI]

    Machel, Hans

    Curl Flame Fractal Rib cage and neck of a Cretaceous plesiosaur (elasmosaur) Fretted terrain (unit of Gusev Crater, Mars narrow channels scarp narrow ridge Basin Floor Assemblage Basin oor unit 1--Forms

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

    E-Print Network [OSTI]

    Kewlani, Gaurav

    2014-01-01T23:59:59.000Z

    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 ...

  4. Assessment of EEM approach for 3D expanding wrinkled premixed flames

    E-Print Network [OSTI]

    Boyer, Edmond

    /methane, air/propane and air/hydrogen flames are measured at atmo- spheric pressure. An internal combustion engine-like configuration, with an optically accessible cylindrical combustion chamber has also been

  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.

    2005-01-01T23:59:59.000Z

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

    SciTech Connect (OSTI)

    Veloo, Peter S.; Egolfopoulos, Fokion N.

    2011-01-01T23:59:59.000Z

    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.

  7. OH radical imaging in a DI diesel engine and the structure of the early diffusion flame

    SciTech Connect (OSTI)

    Dec, J.E.; Coy, E.B.

    1996-03-01T23:59:59.000Z

    Laser-sheet imaging studies have considerably advanced our understanding of diesel combustion; however, the location and nature of the flame zones within the combusting fuel jet have been largely unstudied. To address this issue, planar laser-induced fluorescence (PLIF) imaging of the OH radical has been applied to the reacting fuel jet of a direct-injection diesel engine of the ``heavy-duty`` size class, modified for optical access. An Nd:YAG-based laser system was used to pump the overlapping Q{sub 1}9 and Q{sub 2}8 lines of the (1,0) band of the A{yields}X transition at 284.01 nm, while the fluorescent emission from both the (0,O) and (1, I) bands (308 to 320 nm) was imaged with an intensified video camera. This scheme allowed rejection of elastically scattered laser light, PAH fluorescence, and laser-induced incandescence. OH PLIF is shown to be an excellent diagnostic for diesel diffusion flames. The signal is strong, and it is confined to a narrow region about the flame front because the threebody recombination reactions that reduce high flame-front OH concentrations to equilibrium levels occur rapidly at diesel pressures. No signal was evident in the fuel-rich premixed flame regions where calculations and burner experiments indicate that OH concentrations will be below detectable limits. Temporal sequences of OH PLIF images are presented showing the onset and development of the early diffusion flame up to the time that soot obscures the images. These images show that the diffusion flame develops around the periphery of the-downstream portion of the reacting fuel jet about half way through the premixed burn spike. Although affected by turbulence, the diffusion flame remains at the jet periphery for the rest of the imaged sequence.

  8. 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).

  9. Investigation of the processes controlling the flame generation of refractory materials

    SciTech Connect (OSTI)

    Katz, J.L.

    1992-01-01T23:59:59.000Z

    The processes involved in the formation of mixed oxides powders were studied using the counterflow diffusion flame burner. Powders of different morphologies were obtained by varying the flame conditions (temperature, residence time) and the concentration ratio of the oxides precursors. In-situ particle size and number density were determined using dynamic light scattering and 90{degrees} light scattering. A thermophoretic sampling method and a larger scale powder collection device also was used to collect particles, and their size and morphology examined using transmission electron microscopy, X-ray diffraction and surface area measurement by gas absorption (BET). Our emphasis has been on TiO{sub 2}-SiO{sub 2}, SiO{sub 2}-GeO{sub 2} and Al{sub 2}O{sub 3}-TiO{sub 2}. The powders had a core-mantle-like (one oxide coated by the other) at low elevations in the burner and uniform mixture at higher elevations. They form chain-like structures in a low temperature flame and spherical particles in a higher temperature flame. Nanometer sized homogeneous particles of Aluminum Titanate could be obtained using Al(CH{sub 3}){sub 3} and TiCl{sub 4} as precursors both in a hydrogen fueled and a methane fueled counterflow diffusion flame burner, as well as in a hydrogen fueled parallel-flow diffusion flame burner.

  10. Pressure change and transport process on flames formed in a stretched, rotating flow

    SciTech Connect (OSTI)

    Yamamoto, Kazuhiro [Toyohashi Univ. of Technology, Aichi (Japan). Dept. of Mechanical Engineering] [Toyohashi Univ. of Technology, Aichi (Japan). Dept. of Mechanical Engineering

    1999-08-01T23:59:59.000Z

    Flame characteristics in a stretched, rotating flow have been investigated by numerical simulation of tubular laminar flames for lean hydrogen, methane, and propane/air mixtures. Twin planar flames in counterflow have been also simulated for comparison. A fixed inlet velocity at the porous wall of the burner was assumed in all cases, and the cylindrical containing tube (radius R = 9.5 mm) was either maintained stationary or rotated. Results showed that, within the range studied, the flame temperatures always increase monotonically with increasing fuel concentration, and at the same time the reaction zones move outwards. However, while the introduction of rotation also causes a monotonic temperature increase of hydrogen and methane air mixtures, that of a propane/air mixture decreases. The temperature change with rotation becomes smaller with an increase of the fuel concentration. As a consequence of the centrifugal force, {rho}{nu}{sub {theta}}{sup 2}/r, induced by the rotation, a pressure gradient is formed in the cylindrical containing tube, with low pressure along the axis. The pressure gradient at the outer, unburnt edge of the flame reaction zone becomes smaller as the fuel concentration increases. The resultant decreased mass transport by pressure diffusion provides an explanation for part of the above-mentioned temperature change associated with rotation. The remainder of the effect is associated with changed stretch characteristics of the flames.

  11. 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)

    2011-01-15T23:59:59.000Z

    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)

  12. Stabilizer Formalism for Operator Quantum Error Correction

    E-Print Network [OSTI]

    David Poulin

    2006-06-14T23:59:59.000Z

    Operator quantum error correction is a recently developed theory that provides a generalized framework for active error correction and passive error avoiding schemes. In this paper, we describe these codes in the stabilizer formalism of standard quantum error correction theory. This is achieved by adding a "gauge" group to the standard stabilizer definition of a code that defines an equivalence class between encoded states. Gauge transformations leave the encoded information unchanged; their effect is absorbed by virtual gauge qubits that do not carry useful information. We illustrate the construction by identifying a gauge symmetry in Shor's 9-qubit code that allows us to remove 4 of its 8 stabilizer generators, leading to a simpler decoding procedure and a wider class of logical operations without affecting its essential properties. This opens the path to possible improvements of the error threshold of fault-tolerant quantum computing.

  13. Real Oscillations of Virtual Neutrinos

    E-Print Network [OSTI]

    W. Grimus; P. Stockinger

    1996-03-28T23:59:59.000Z

    We study the conditions for neutrino oscillations in a field theoretical approach by taking into account that only the neutrino production and detection processes, which are localized in space around the coordinates $\\vec{x}_P$ and $\\vec{x}_D$, respectively, can be manipulated. In this sense the neutrinos whose oscillations are investigated appear as virtual lines connecting production with detection in the total Feynman graph and all neutrino fields or states to be found in the discussion are mass eigenfields or eigenstates. We perform a thorough examination of the integral over the spatial components of the inner neutrino momentum and show that in the asymptotic limit $L=|\\vec{x}_D - \\vec{x}_P| \\rightarrow \\infty$ the virtual neutrinos become ``real'' and under certain conditions the usual picture of neutrino oscillations emerges without ambiguities.

  14. Real oscillations of virtual neutrinos

    E-Print Network [OSTI]

    Grimus, Walter

    1996-01-01T23:59:59.000Z

    We study the conditions for neutrino oscillations in a field theoretical approach by taking into account that only the neutrino production and detection processes, which are localized in space around the coordinates \\vec{x}_P and \\vec{x}_D, respectively, can be manipulated. In this sense the neutrinos whose oscillations are investigated appear as virtual lines connecting production with detection in the total Feynman graph and all neutrino fields or states to be found in the discussion are mass eigenfields or eigenstates. We perform a thorough examination of the integral over the spatial components of the inner neutrino momentum and show that in the asymptotic limit L=|\\vec{x}_D - \\vec{x}_P| \\rightarrow \\infty the virtual neutrinos become ``real'' and under certain conditions the usual picture of neutrino oscillations emerges without ambiguities.

  15. Computer Assisted Virtual Environment - CAVE

    ScienceCinema (OSTI)

    Erickson, Phillip; Podgorney, Robert; Weingartner, Shawn; Whiting, Eric

    2014-06-09T23:59:59.000Z

    Research at the Center for Advanced Energy Studies is taking on another dimension with a 3-D device known as a Computer Assisted Virtual Environment. The CAVE uses projection to display high-end computer graphics on three walls and the floor. By wearing 3-D glasses to create depth perception and holding a wand to move and rotate images, users can delve into data.

  16. Science with Virtual Observatory Tools

    E-Print Network [OSTI]

    P. Padovani

    2004-11-12T23:59:59.000Z

    The Virtual Observatory is now mature enough to produce cutting-edge science results. The exploitation of astronomical data beyond classical identification limits with interoperable tools for statistical identification of sources has become a reality. I present the discovery of 68 optically faint, obscured (i.e., type 2) active galactic nuclei (AGN) candidates in the two GOODS fields using the Astrophysical Virtual Observatory (AVO) prototype. Thirty-one of these sources have high estimated X-ray powers (>10^44 erg/s) and therefore qualify as optically obscured quasars, the so-called QSO 2. The number of these objects in the GOODS fields is now 40, an improvement of a factor > 4 when compared to the only 9 such sources previously known. By going ~ 3 magnitudes fainter than previously known type 2 AGN in the GOODS fields the AVO is sampling a region of redshift -- power space much harder to reach with classical methods. I also discuss the AVO move to our next phase, the EURO-VO, and our short-term plans to continue doing science with the Virtual Observatory.

  17. Virtual data in CMS analysis

    SciTech Connect (OSTI)

    A. Arbree et al.

    2003-10-01T23:59:59.000Z

    The use of virtual data for enhancing the collaboration between large groups of scientists is explored in several ways: by defining ''virtual'' parameter spaces which can be searched and shared in an organized way by a collaboration of scientists in the course of their analysis; by providing a mechanism to log the provenance of results and the ability to trace them back to the various stages in the analysis of real or simulated data; by creating ''check points'' in the course of an analysis to permit collaborators to explore their own analysis branches by refining selections, improving the signal to background ratio, varying the estimation of parameters, etc.; by facilitating the audit of an analysis and the reproduction of its results by a different group, or in a peer review context. We describe a prototype for the analysis of data from the CMS experiment based on the virtual data system Chimera and the object-oriented data analysis framework ROOT. The Chimera system is used to chain together several steps in the analysis process including the Monte Carlo generation of data, the simulation of detector response, the reconstruction of physics objects and their subsequent analysis, histogramming and visualization using the ROOT framework.

  18. Combustor oscillating pressure stabilization and method

    DOE Patents [OSTI]

    Gemmen, Randall S. (Morgantown, WV); Richards, George A. (Morgantown, WV); Yip, Mui-Tong Joseph (Morgantown, WV); Robey, Edward H. (Westover, WV); Cully, Scott R. (Morgantown, WV); Addis, Richard E. (Smithfield, PA)

    1998-01-01T23:59:59.000Z

    High dynamic pressure oscillations in hydrocarbon-fueled combustors typically occur when the transport time of the fuel to the flame front is at some fraction of the acoustic period. These oscillations are reduced to acceptably lower levels by restructuring or repositioning the flame front in the combustor to increase the transport time. A pilot flame front located upstream of the oscillating flame and pulsed at a selected frequency and duration effectively restructures and repositions the oscillating flame in the combustor to alter the oscillation-causing transport time.

  19. Measurements and modeling of soot formation and radiation in microgravity jet diffusion flames

    SciTech Connect (OSTI)

    Ku, J.C.; Tong, L. [Wayne State Univ., Detroit, MI (United States). Mechanical Engineering Dept.; Greenberg, P.S. [NASA Lewis Research Center, Cleveland, OH (United States). Microgravity Combustion Branch

    1996-12-31T23:59:59.000Z

    This is a computational and experimental study for soot formation and radiative heat transfer in jet diffusion flames under normal gravity (1-g) and microgravity (0-g) conditions. Instantaneous soot volume fraction maps are measured using a full-field imaging absorption technique developed by the authors. On modeling, the authors have coupled flame structure and soot formation models with detailed radiation transfer calculations. Favre-averaged boundary layer equations with a k-e-g turbulence model are used to predict the flow field, and a conserved scalar approach with an assumed {beta}-pdf are used to predict gaseous species mole fraction. Scalar transport equations are used to describe soot volume fraction and number density distributions, with formation and oxidation terms modeled by one-step rate equations and thermophoretic effects included. An energy equation is included to couple flame structure and radiation analyses through iterations, neglecting turbulence-radiation interactions. The YIX solution for a finite cylindrical enclosure is used for radiative heat transfer calculations. The spectral absorption coefficient for soot aggregates is calculated from the Rayleigh solution using complex refractive index data from a Drude-Lorentz model. The exponential-wide-band model is used to calculate the spectral absorption coefficient for H{sub 2}O and CO{sub 2}. Predicted soot volume fraction and temperature results agree well with published data for a normal gravity co-flow laminar flames and turbulent jet flames. Predicted soot volume fraction results also agree with the data for 1-g and 0-g laminar jet flames as well as 1-g turbulent jet flames.

  20. 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)

    2009-06-15T23:59:59.000Z

    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)

  1. Virtual(ly) Queer: Anti-Genealogy and Obsessive-Compulsion in Bechdels' Fun Home

    E-Print Network [OSTI]

    Gill-Peterson, Julian

    2012-01-01T23:59:59.000Z

    will require giving up on genealogy to notice the virtuallyVirtual(ly) Queer: Anti-Genealogy and Obsessive-Compulsionlines are the form of genealogies, the tracing of lines of

  2. Numerically Estimating Internal Models of Dynamic Virtual Objects

    E-Print Network [OSTI]

    Sekuler, Robert

    human subjects to manipulate a computer-animated virtual object. This virtual object (vO) was a high, human cognition, human information processing, ideal performer, internal model, virtual object, virtual, specifically how humans acquire an internal model of a dynamic virtual object. Our methodology minimizes

  3. Active Perception in Virtual Humans Tamer F. Rabie Demetri Terzopoulos

    E-Print Network [OSTI]

    Terzopoulos, Demetri

    Active Perception in Virtual Humans Tamer F. Rabie Demetri Terzopoulos Department of Electrical prescribes artificial animals, or animats, situated in physics- based virtual worlds as autonomous virtual a pro- totype animat vision implementation within realistic virtual human soldiers situated in a virtual

  4. A virtual company concept for reservoir management

    SciTech Connect (OSTI)

    Martin, F.D. [Dave Martin and Associates, Inc. (United States); Kendall, R.P.; Whitney, E.M. [Los Alamos National Lab., NM (United States)

    1998-12-31T23:59:59.000Z

    This paper describes how reservoir management problems were pursued with a virtual company concept via the Internet and World Wide Web. The focus of the paper is on the implementation of virtual asset management teams that were assembled with small independent oil companies. The paper highlights the mechanics of how the virtual team transferred data and interpretations, evaluated geological models of complex reservoirs, and used results of simulation studies to analyze various reservoir management strategies.

  5. Virtual Hydropower Prospecting – Searching for Hydropower Gold

    SciTech Connect (OSTI)

    Douglas G. Hall

    2007-12-01T23:59:59.000Z

    The availability of geographic information system (GIS) tools and analytical modeling of natural streams has made it possible to perform virtual “river inventories” that were formerly done using topographic maps, stream flow estimates, and physical reconnaissance. The Idaho National Laboratory (INL) in collaboration with the U.S. Geological Survey (USGS) virtually assessed the gross power potential of all natural streams in the United States of America and identified feasible potential project sites and estimated their developable power potential. The results of this virtual prospecting have been incorporated into a GIS application called the Virtual Hydropower Prospector that is available for public use on the Internet.

  6. Virtual Training Centre For CNC: a Sample Virtual Training Environment Mehmet Sahin1

    E-Print Network [OSTI]

    Aristomenis, Antoniadis

    Virtual Training Centre For CNC: a Sample Virtual Training Environment Mehmet Sahin1 , Süleyman bilalis@dpem.tuc.gr Abstract It is a fact that virtual training has been a scope of interest for vocational training for a very long time. However, it needs more time to be more common in all specific

  7. Soot formation in laminar premixed methane/oxygen flames at atmospheric pressure

    SciTech Connect (OSTI)

    Xu, F.; Lin, K.C.; Faeth, G.M. [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Aerospace Engineering] [Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Aerospace Engineering

    1998-10-01T23:59:59.000Z

    Flame structure and soot formation were studied within soot-containing laminar premixed methane/oxygen flames at atmospheric pressure. The following measurements were made: soot volume fractions by laser extinction, soot temperatures by multiline emission, gas temperatures (where soot was absent) by corrected fine-wire thermocouples, soot structure by thermophoretic sampling and transmission electron microscope (TEM), major gas species concentrations by sampling and gas chromatography, and gas velocities by laser velocimetry. Present measurements of gas species concentrations were in reasonably good agreement with earlier measurements due to Ramer et al. as well as predictions based on the detailed mechanisms of Frenklach and co-workers and Leung and Lindstedt; the predictions also suggest that H atom concentrations are in local thermodynamic equilibrium throughout the soot formation region. Using this information, it was found that measured soot surface growth rates could be correlated successfully by predictions based on the hydrogen-abstraction/carbon-addition (HACA) mechanisms of both Frenklach and co-workers and Colket and Hall, extending an earlier assessment of these mechanisms for premixed ethylene/air flames to conditions having larger H/C ratios and acetylene concentrations. Measured primary soot particle nucleation rates were somewhat lower than the earlier observations for laminar premixed ethylene/air flames and were significantly lower than corresponding rates in laminar diffusion flames, for reasons that still must be explained.

  8. Reduction of soot emissions by iron pentacarbonyl in isooctane diffusion flames

    SciTech Connect (OSTI)

    Kim, K.B.; Masiello, K.A.; Hahn, D.W. [Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611 (United States)

    2008-07-15T23:59:59.000Z

    Light-scattering measurements, in situ laser-induced fluorescence, and thermophoretic sampling with transmission electron microscopy (TEM) analysis, were performed in laboratory isooctane diffusion flames seeded with 4000 ppm iron pentacarbonyl. These measurements allowed the determination of the evolution of the size, number density, and volume fraction of soot particles through the flame. Comparison to unseeded flame data provided a detailed assessment of the effects of iron addition on soot particle inception, growth, and oxidation processes. Iron was found to produce a minor soot-enhancing effect at early residence times, while subsequent soot particle growth was largely unaffected. It is concluded that primarily elemental iron is incorporated within the soot particles during particle inception and growth. However, iron addition was found to enhance the rate of soot oxidation during the soot burnout regime, yielding a two-thirds reduction in overall soot emissions. In situ spectroscopic measurements probed the transient nature of elemental iron throughout the flame, revealing significant loss of elemental iron, presumably to iron oxides, with increasing flame residence, suggesting catalysis of soot oxidation via iron oxide species. (author)

  9. Soot suppression by ferrocene in laminar ethylene/air nonpremixed flames

    SciTech Connect (OSTI)

    Zhang, J.; Megaridis, C.M. [Univ. of Illinois, Chicago, IL (United States). Dept. of Mechanical Engineering] [Univ. of Illinois, Chicago, IL (United States). Dept. of Mechanical Engineering

    1996-06-01T23:59:59.000Z

    An experimental investigation is presented on the origin of the soot suppressing role of ferrocene additive in laminar, coannular, ethylene/air nonpremixed flames. The conditions examined involve laminar flames operating above and below their smoke point. In-flame diagnostics are employed to discern the interaction between the soot matrix and additive combustion products. The data presented in a previous study, as produced by thermophoretic sampling, transmission electron microscopy and high-resolution microanalysis techniques, are supplemented by soot volume fraction, temperature, and soot primary size measurements to unravel the mechanisms through which ferrocene combustion products influence soot formation processes. Furthermore, Z-contrast scanning/transmission electron microscopy is used to examine the over-fire aerosol and, in turn, provide insight on the fine-scale dispersion of iron fragments within the carbonaceous soot matrix. It is shown that ferrocene seeding of the fuel stream accelerates the particular inception mechanisms, but does not influence soot loadings when soot growth is dominant. Ferrocene is also found to enhance soot oxidation rates near the flame terminus. It is concluded that the fine-scale incorporation of iron compounds within the soot matrix is a primary factor for the soot suppressing role of ferrocene in nonpremixed flames.

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

    SciTech Connect (OSTI)

    Oßwald, P.; Köhler, M. [German Aerospace Center (DLR) – Institute of Combustion Technology, Stuttgart 70569 (Germany)] [German Aerospace Center (DLR) – Institute of Combustion Technology, Stuttgart 70569 (Germany); Hemberger, P.; Bodi, A.; Gerber, T. [Molecular Dynamics Group, Paul Scherrer Institut, CH-5232 Villigen (Switzerland)] [Molecular Dynamics Group, Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Bierkandt, T.; Akyildiz, E.; Kasper, T., E-mail: tina.kasper@uni-due.de [Mass Spectrometry in Reactive Flows - Thermodynamics (IVG), University of Duisburg-Essen, Duisburg (Germany)

    2014-02-15T23:59:59.000Z

    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.

  11. Flame acceleration and DDT in channels with obstacles: Effect of obstacle spacing

    SciTech Connect (OSTI)

    Gamezo, Vadim N.; Oran, Elaine S. [Laboratory for Computational Physics and Fluid Dynamics, Naval Research Laboratory, Washington, DC 20375 (United States); Ogawa, Takanobu [Department of Mechanical Engineering, Seikei University, Kichijoji-Kitamachi, Musashino-shi, Tokyo, 180-8633 (Japan)

    2008-10-15T23:59:59.000Z

    We study flame acceleration and deflagration-to-detonation transition (DDT) in obstructed channels using 2D reactive Navier-Stokes numerical simulations. The energy release rate for the stoichiometric hydrogen-air mixture is modeled by one-step Arrhenius kinetics. Computations performed for channels with symmetrical and staggered obstacle configurations show two main effects of obstacle spacing S. First, more obstacles per unit length create more perturbations that increase the flame surface area more quickly, and therefore the flame speed grows faster. Second, DDT occurs more easily when the obstacle spacing is large enough for Mach stems to form between obstacles. These two effects are responsible for three different regimes of flame acceleration and DDT observed in simulations: (1) Detonation is ignited when a Mach stem formed by the diffracting shock reflecting from the side wall collides with an obstacle, (2) Mach stems do not form, and the detonation is not ignited, and (3) Mach stems do not form, but the leading shock becomes strong enough to ignite a detonation by direct collision with the top of an obstacle. Regime 3 is observed for small S and involves multiple isolated detonations that appear between obstacles and play a key role in final stages of flame and shock acceleration. For Regime 1 and staggered obstacle configurations, we observe resonance phenomena that significantly reduce the DDT time when S/2 is comparable to the channel width. Effects of imposed symmetry and stochasticity on DDT phenomena are also considered. (author)

  12. Aromatics oxidation and soot formation in flames. Progress report, August 15, 1990--August 14, 1993

    SciTech Connect (OSTI)

    Howard, J.B.; Pope, C.J.; Shandross, R.A.; Yadav, T.

    1993-04-01T23:59:59.000Z

    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 confirm or determine rate constants for, the main benzene oxidation reactions in flames, and to characterize soot and fullerenes and their formation mechanisms and kinetics. Stable and radical species profiles in the aromatics oxidation study are measured using molecular beam sampling with on-line mass spectrometry. The rate of soot formation measured by conventional optical techniques is found to support the hypotheses that particle inception occurs through reactive coagulation of high molecular weight PAH in competition with destruction by OHattack, and that the subsequent growth of the soot mass occurs through addition reactions of PAH and C{sub 2}H{sub 2} with the soot particles. During the first year of this reporting period, fullerenes C{sub 60} and C{sub 70} in substantial quantities were found in the flames being studied. The fullerenes were recovered, purified and spectroscopically identified. The yields of C{sub 60} and C{sub 70} were then determined over ranges of conditions in low-pressure premixed flames of benzene and oxygen.

  13. Virtualized Network Control: Final Report

    SciTech Connect (OSTI)

    Ghani, Nasir [University of New Mexico

    2013-02-01T23:59:59.000Z

    This document is the final report for the Virtualized Network Control (VNC) project, which was funded by the United States Department of Energy (DOE) Office of Science. This project was also informally referred to as Advanced Resource Computation for Hybrid Service and TOpology NEtworks (ARCHSTONE). This report provides a summary of the project's activities, tasks, deliverable, and accomplishments. It also provides a summary of the documents, software, and presentations generated as part of this projects activities. Namely, the Appendix contains an archive of the deliverables, documents, and presentations generated a part of this project.

  14. Reactive behaviour for autonomous virtual agents using fuzzy logic 

    E-Print Network [OSTI]

    Jaafar, Jafreezal

    2009-11-26T23:59:59.000Z

    One of the fundamental aspects of a virtual environment is the virtual agents that inhabit them. In many applications, virtual agents are required to perceive input information from their environment and make decisions ...

  15. Profiling and Modeling Resource Usage of Virtualized Applications

    E-Print Network [OSTI]

    Simunic, Tajana

    , and fully managed adaptive infrastruc- tures. Virtualization technologies promise great opportunities for reducing energy and hardware costs through server consolidation. Moreover, virtualization can optimize needs. However, to safely transition an application running natively on real hardware to a virtualized

  16. On Flame-Wall Thermal-Coupling in Micro Combustors Yong Fan, Yuji Suzuki, and Nobuhide Kasagi

    E-Print Network [OSTI]

    Kasagi, Nobuhide

    On Flame-Wall Thermal-Coupling in Micro Combustors Yong Fan, Yuji Suzuki, and Nobuhide Kasagi Department of Mechanical Engineering, The University of Tokyo, Japan Keywords: Micro combustor, Premixed of premixed CH4/Air flame propagation and quenching in three quartz combustors with chamber depth of 0.7 mm, 1

  17. Oscillating Flame in Wall Temperature-Controlled Ultra-Thin Quartz Channels Yong FAN, Yuji SUZUKI and Nobuhide Kasagi

    E-Print Network [OSTI]

    Kasagi, Nobuhide

    associated with combustion in micro combustors lead to the finding that wall thermal and chemical conditions shows that the flame is quenched by wall heat loss. Key Words: Micro combustor, Oscillating flame, Phase of intense investigations on micro combustors. On the other hand, studies on new phenomena and physics

  18. Mapping of soot particles in a weakly sooting diffusion flame by aerosol techniques

    SciTech Connect (OSTI)

    Hepp, H.; Siegmann, K. [Federal Inst. of Tech., Zuerich (Switzerland). Lab. for Solid State Physics] [Federal Inst. of Tech., Zuerich (Switzerland). Lab. for Solid State Physics

    1998-10-01T23:59:59.000Z

    The evolution of detailed particle size distributions has been measured along the centerline of an axisymmetric diffusion flame of CH{sub 4} + Ar burning in air at 1 atm. Soot particles with mean diameters of 3--18 nm were observed. Changes in the size distribution exhibited zones where either nucleation, coagulation, or destruction of soot particles dominated. These highly sensitive measurements were made by microprobe sampling with an immediate dilution of 1:400, to quench the aerosol, and by subsequent application of aerosol measurement techniques. In parallel, the yield of photoemitted electrons from size-selected particles was determined. The yield shows a characteristic dependence on location in the flame, indicating changes of the particle`s surface. Multiphoton, time-of-flight mass spectrometry was used to investigate the correlation between polycyclic aromatic hydrocarbons in the flame and enhanced photoemission yield from the soot particles.

  19. 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

  20. WebGL for Dynamic Virtual Globes

    E-Print Network [OSTI]

    Plotkin, Joshua B.

    WebGL for Dynamic Virtual Globes Patrick Cozzi Analytical Graphics, Inc. pcozzi@agi.com @pjcozzi #12;No anisotropic filtering Overview Cesium A WebGL virtual globe for visualizing dynamic data-side #12;Cesium Architecture - Renderer Scene Renderer Core Renderer - a thin abstraction over Web

  1. Some Aspects of Deeply Virtual Compton Scattering

    E-Print Network [OSTI]

    Elena Kuchina

    2004-05-10T23:59:59.000Z

    We consider different aspects of the virtual Compton amplitude in QCD on two examples: small-x physics accessible in the Regge regime and twist-3 approximation in the description of DVCS through the general parton distributions. Using this model, we give an estimate for the cross section of deeply virtual Compton scattering for the kinematics of CEBAF at Jefferson Lab.

  2. A Deeply Virtual Compton Scattering Amplitude

    E-Print Network [OSTI]

    M. Capua; S. Fazio; R. Fiore; L. Jenkovszky; F. Paccanoni

    2006-07-07T23:59:59.000Z

    A factorized Regge-pole model for deeply virtual Compton scattering is suggested. The use of an effective logarithmic Regge-Pomeron trajectory provides for the description of both ``soft'' (small $|t|$) and ``hard'' (large $|t|$) dynamics. The model contains explicitly the photoproduction and the DIS limits and fits the existing HERA data on deeply virtual Compton scattering.

  3. QCD Sum Rules and Virtual Compton Scattering

    E-Print Network [OSTI]

    A. V. Radyushkin

    1996-09-19T23:59:59.000Z

    In this talk I report on recent progress in a few areas closely related to the virtual Compton scattering studies. In particular, I discuss the quark-hadron duality estimate of the $\\gamma^* p \\to \\Delta^+$ transition, QCD sum rule calculation of the $\\gamma \\gamma^* \\to \\pi^0$ form factor, and application of perturbative QCD to deeply virtual Compton scattering at small $t$.

  4. Storage Management in Virtualized Cloud Environment

    E-Print Network [OSTI]

    Liu, Ling

    the performance bottlenecks in a virtualized setup and understanding the implications of workload combinations present the measurement results of detailed experiments conducted on a virtualized setup focusing/applications enable ubiquitous access to data besides the ability to harness massive computing power even from

  5. Green Virtual Enterprises and their Breeding Environments

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Green Virtual Enterprises and their Breeding Environments David Romero, Arturo Molina Tecnológico. This paper introduces a Green Virtual Enterprise (GVE) model as an emerging sustainable manufacturing and logistics mode focused on offering, delivering and recovering green products to/from the market, under

  6. Coordination and sociability for intelligent virtual agents

    E-Print Network [OSTI]

    Grimaldo, Francisco

    produce low quality animations where characters do not act realistically. Moreover, virtual humans an elegant and formal framework to animate synthetic humans. When designing such agents, the main concern has that will be finally animated. Virtual actors normally operate in dynamic resource bounded contexts; thus, multi

  7. PREPARING THE VIRTUAL CLASSROOM FOR DISTANCE DELIVERY

    E-Print Network [OSTI]

    Dyer, Bill

    of humans and their companion domestic animals and livestock. Students learn that there are certain "at riskPREPARING THE VIRTUAL CLASSROOM FOR DISTANCE DELIVERY: MEDICAL-VETERINARY ENTOMOLOGY CLINICS laboratory," library materials, conventional lectures and the 43 virtual patients in the clinics

  8. 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)

    2010-07-05T23:59:59.000Z

    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.

  9. Soot formation and temperature structure in small methane-oxygen diffusion flames at subcritical and supercritical pressures

    SciTech Connect (OSTI)

    Joo, Hyun I.; Guelder, Oemer L. [University of Toronto, Institute for Aerospace Studies, 4925 Dufferin Street, Toronto, Ont. (Canada)

    2010-06-15T23:59:59.000Z

    An experimental study was conducted to examine the characteristics of laminar methane-oxygen diffusion flames up to 100 atmospheres. The influence of pressure on soot formation and on the structure of the temperature field was investigated over the pressure range of 10-90 atmospheres in a high-pressure combustion chamber using a non-intrusive, line-of-sight spectral soot emission diagnostic technique. Two distinct zones characterized the appearance of a methane and pure oxygen diffusion flame: an inner luminous zone similar to the methane-air diffusion flames, and an outer diffusion flame zone which is mostly blue. The flame height, marked by the visible soot radiation emission, was reduced by over 50% over the pressure range of 10-100 atmospheres. Between 10 and 40 atmospheres, the soot levels increased with increasing pressure; however, above 40 atmospheres the soot concentrations decreased with increasing pressure. (author)

  10. SMART Wind Consortium Composites Subgroup Virtual Meeting: Advanced...

    Energy Savers [EERE]

    SMART Wind Consortium Composites Subgroup Virtual Meeting: Advanced Manufacturing of Wind Turbine Blades SMART Wind Consortium Composites Subgroup Virtual Meeting: Advanced...

  11. Integrated Virtual Lab in Supporting Heavy Duty Engine and Vehicle...

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

    Virtual Lab in Supporting Heavy Duty Engine and Vehicle Emission Rulemaking Integrated Virtual Lab in Supporting Heavy Duty Engine and Vehicle Emission Rulemaking Presentation...

  12. Proposed Virtual Center for Excellence for Metal Hydride Development

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

    & Engineering Sciences Center Atoms to Continuum Proposed Virtual Center of Excellence Proposed Virtual Center of Excellence for Metal Hydride Development for Metal Hydride...

  13. Energy Department Launches Virtual Hackathon to Build the Next...

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

    Launches Virtual Hackathon to Build the Next Big Solar Software Solutions Energy Department Launches Virtual Hackathon to Build the Next Big Solar Software Solutions February 20,...

  14. Virtual Center of Excellence for Hydrogen Storage - Chemical...

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

    Virtual Center of Excellence for Hydrogen Storage - Chemical Hydrides Virtual Center of Excellence for Hydrogen Storage - Chemical Hydrides Presentation from the Hydrogen Storage...

  15. BioenergizeME Virtual Science Fair: The Environmental Benefit...

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

    The Environmental Benefit of Bioenergy BioenergizeME Virtual Science Fair: The Environmental Benefit of Bioenergy BioenergizeME Virtual Science Fair: The Environmental Benefit of...

  16. BioenergizeME Virtual Science Fair: Science & Technology Sustainable...

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

    Science & Technology Sustainable Transportation Fuels BioenergizeME Virtual Science Fair: Science & Technology Sustainable Transportation Fuels BioenergizeME Virtual Science Fair:...

  17. T-678: Red Hat Enterprise Virtualization Hypervisor VLAN Packet...

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

    8: Red Hat Enterprise Virtualization Hypervisor VLAN Packet Processing Flaw Lets Remote Users Deny Service T-678: Red Hat Enterprise Virtualization Hypervisor VLAN Packet...

  18. Buildings of the Future Research Project Launch and Virtual Panel...

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

    Buildings of the Future Research Project Launch and Virtual Panel Discussion on Building Technology Trends Buildings of the Future Research Project Launch and Virtual Panel...

  19. 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. [Massachusetts Institute of Technology, Department of Mechanical Engineering, Cambridge, MA 02139 (United States)

    2010-04-15T23:59:59.000Z

    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)

  20. Turbulent flame speeds in ducts and the deflagration/detonation transition

    SciTech Connect (OSTI)

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

    2008-07-15T23:59:59.000Z

    A methodology is proposed for determining whether a deflagration-to-detonation transition (DDT) might occur for flame propagation along a duct with baffles, closed at the ignition end. A flammable mixture can attain a maximum turbulent burning velocity. If this is sufficiently high, a strong shock is formed ahead of the flame. It is assumed that this maximum burning velocity is soon attained and on the basis of previous studies, this value can be obtained for the given conditions. The increase in temperature and pressure of the reactants, due to the shock, further increases the maximum turbulent burning velocity. The gas velocity ahead of the flame is linked to one-dimensional shock wave equations in a numerical analysis. The predicted duct flame speeds with the appropriate maximum turbulent burning velocities are in good agreement with those measured in the slow and fast flame regimes of a range of CH{sub 4}-air and H{sub 2}-air mixtures. DDTs are possible if autoignition of the reactants occurs in the time available, and if the projected flame speed approaches the Chapman-Jouguet velocity at the same temperature and pressure. Prediction of the first condition requires values of the autoignition delay time of the mixture at the shocked temperatures and pressures. Prediction of the second requires values of the laminar burning velocity and Markstein number. With the appropriate values of these parameters, it is shown numerically that there is no DDT with CH{sub 4}-air. With H{sub 2}-air, the onset of DDT occurs close to the values of equivalence ratio at which it has been observed experimentally. The effects of different duct sizes also are predicted, although details of the DDT cannot be predicted. Extension of the study to a wider range of fuels requires more data on their laminar burning velocities and Markstein numbers at higher temperatures and pressures and on autoignition delay times at lower temperatures and pressures. (author)

  1. Probe measurements and numerical model predictions of evolving size distributions in premixed flames

    SciTech Connect (OSTI)

    De Filippo, A.; Sgro, L.A.; Lanzuolo, G.; D'Alessio, A. [Dipartimento di Ingegneria Chimica, Universita degli Studi di Napoli Federico II, Piazzale Tecchio 80, 80125 Napoli (Italy)

    2009-09-15T23:59:59.000Z

    Particle size distributions (PSDs), measured with a dilution probe and a Differential Mobility Analyzer (DMA), and numerical predictions of these PSDs, based on a model that includes only coagulation or alternatively inception and coagulation, are compared to investigate particle growth processes and possible sampling artifacts in the post-flame region of a C/O = 0.65 premixed laminar ethylene-air flame. Inputs to the numerical model are the PSD measured early in the flame (the initial condition for the aerosol population) and the temperature profile measured along the flame's axial centerline. The measured PSDs are initially unimodal, with a modal mobility diameter of 2.2 nm, and become bimodal later in the post-flame region. The smaller mode is best predicted with a size-dependent coagulation model, which allows some fraction of the smallest particles to escape collisions without resulting in coalescence or coagulation through the size-dependent coagulation efficiency ({gamma}{sub SD}). Instead, when {gamma} = 1 and the coagulation rate is equal to the collision rate for all particles regardless of their size, the coagulation model significantly under predicts the number concentration of both modes and over predicts the size of the largest particles in the distribution compared to the measured size distributions at various heights above the burner. The coagulation ({gamma}{sub SD}) model alone is unable to reproduce well the larger particle mode (mode II). Combining persistent nucleation with size-dependent coagulation brings the predicted PSDs to within experimental error of the measurements, which seems to suggest that surface growth processes are relatively insignificant in these flames. Shifting measured PSDs a few mm closer to the burner surface, generally adopted to correct for probe perturbations, does not produce a better matching between the experimental and the numerical results. (author)

  2. Increasing the chemical content of turbulent flame models through the use of parallel computing

    SciTech Connect (OSTI)

    Yam, C.G.; Armstrong, R.; Koszykowski, M.L. [Sandia National Labs., Livermore, CA (United States); Chen, J.Y. [California Univ., Berkeley, CA (United States); Bui-Pham, M.N. [Lawrence Berkeley National Lab., CA (United States)

    1996-10-01T23:59:59.000Z

    This report outlines the effort to model a time-dependent, 2- dimensional, turbulent, nonpremixed flame with full chemistry with the aid of parallel computing tools. In this study, the mixing process and the chemical reactions occurring in the flow field are described in terms of the single-point probability density function (PDF), while the turbulent viscosity is determined by the standard kappa-epsilon model. The initial problem solved is a H[sub 2]/Air flame whose chemistry is described by 28 elementary reactions involving 9 chemical species.

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

    DOE Patents [OSTI]

    Salyer, Ival O. (Dayton, OH)

    1998-08-04T23:59:59.000Z

    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.

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

    DOE Patents [OSTI]

    Salyer, I.O.

    1998-08-04T23:59:59.000Z

    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.

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

    DOE Patents [OSTI]

    Salyer, Ival O. (Dayton, OH)

    1998-08-04T23:59:59.000Z

    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.

    1986-05-01T23:59:59.000Z

    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. Multi-timescale modeling of ignition and flame regimes of n-heptane-air mixtures near spark assisted homogeneous charge compression ignition conditions

    SciTech Connect (OSTI)

    Ju, Yiguang; Sun, Wenting; Burke, M. P.; Gou, Xiaolong; Chen, Zheng

    2011-01-01T23:59:59.000Z

    The flame regimes of ignition and flame propagation as well as transitions between different flame regimes of n-heptane-air mixtures in a one-dimensional, cylindrical, spark assisted homogeneously charged compression ignition (HCCI) reactor are numerically modeled using a multi-timescale method with reduced kinetic mechanism. It is found that the initial mixture temperature and pressure have a dramatic impact on flame dynamics. Depending on the initial temperature gradient, there exist at least six different combustion regimes, an initial single flame front propagation regime, a coupled low temperature and high temperature double-flame regime, a decoupled low temperature and high temperature double-flame regime, a low temperature ignition regime, a single high temperature flame regime, and a hot ignition regime. The results show that the low temperature and high temperature flames have distinct kinetic and transport properties as well as flame speeds, and are strongly influenced by the low temperature chemistry. The pressure and heat release rates are affected by the appearance of different flame regimes and the transitions between them. Furthermore, it is found that the critical temperature gradient for ignition and acoustic wave coupling becomes singular at the negative temperature coefficient (NTC) region. The results show that both the NTC effect and the acoustic wave propagation in a closed reactor have a dramatic impact on the ignition front and acoustic interaction.

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

    E-Print Network [OSTI]

    Im, Hong G.

    2006-01-01T23:59:59.000Z

    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

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

    E-Print Network [OSTI]

    Cellular burning in lean premixed turbulent hydrogen-air flames: coupling experimental. Beckner1, M. J. Lijewski1 1 Center for Computational Science and Engineering, Lawrence Berkeley National for burning the fuel-lean mixtures of hydrogen or hydrogen-rich syngas fuels obtained from the gasification

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

    E-Print Network [OSTI]

    Gülder, �mer L.

    -based to hydrogen-based economy are still under discussion and the implementation of the hydrogen- based economy methane flame in the methane- dominated regime. Copyright ª 2014, Hydrogen Energy Publications, LLC appear to be a promising option to synergistically pave the way toward pure hydrogen- based combustion

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

    E-Print Network [OSTI]

    Stark, Christopher Charles

    2003-01-01T23:59:59.000Z

    it with the two open flame practices. This evaluation was performed by moving the burners over an area that would monitor the temperatures at specified heights and locations. Temperatures were measured using thermocouples placed at heights 7-mm, 150-mm, and 300...

  12. Soot formation and temperature field structure in laminar propane-air diffusion flames at elevated pressures

    SciTech Connect (OSTI)

    Bento, Decio S.; Guelder, OEmer L. [Institute for Aerospace Studies, University of Toronto, 4925 Dufferin Street, Toronto, ON M3H 5T6 (Canada); Thomson, Kevin A. [National Research Council, ICPET Combustion Technology, 1200 Montreal Road M-9, Ontario K1A 0R6 (Canada)

    2006-06-15T23:59:59.000Z

    The effect of pressure on soot formation and the structure of the temperature field was studied in coflow propane-air laminar diffusion flames over the pressure range of 0.1 to 0.73 MPa in a high-pressure combustion chamber. The fuel flow rate was selected so that the soot was completely oxidized within the visible flame and the flame was stable at all pressures. Spectral soot emission was used to measure radially resolved soot volume fraction and soot temperature as a function of pressure. Additional soot volume fraction measurements were made at selected heights using line-of-sight light attenuation. Soot concentration values from these two techniques agreed to within 30% and both methods exhibited similar trends in the spatial distribution of soot concentration. Maximum line-of-sight soot concentration along the flame centerline scaled with pressure; the pressure exponent was about 1.4 for pressures between 0.2 and 0.73 MPa. Peak carbon conversion to soot, defined as the percentage of fuel carbon content converted to soot, also followed a power-law dependence on pressure, where the pressure exponent was near to unity for pressures between 0.2 and 0.73 MPa. Soot temperature measurements indicated that the overall temperatures decreased with increasing pressure; however, the temperature gradients increased with increasing pressure. (author)

  13. Multiscale Modeling of TiO2 Nanoparticle Production in Flame Reactors: Effect of Chemical Mechanism

    E-Print Network [OSTI]

    Raman, Venkat

    , catalysis, energy, and semiconductors. Titanium dioxide (TiO2) nanoparticles are traditionally used and Engineering Mechanics, The UniVersity of Texas, Austin, Texas 78712 For titanium dioxide (TiO2) nanoparticles in the flame with detailed titanium oxidation chemistry, compared to one-step chemistry. Finally, a large

  14. Carbon nanotubes grow in combustion flames Issued on March 31, 2014

    E-Print Network [OSTI]

    Takahashi, Ryo

    Carbon nanotubes grow in combustion flames Issued on March 31, 2014 Quantum chemical simulations reveal an unprecedented relationship between the mechanism of carbon nanotube growth and hydrocarbon of carbon nanotube (CNT) growth and hydrocarbon combustion actually share many similarities. In studies

  15. NOx emission characteristics of counterflow syngas diffusion flames with airstream dilution

    E-Print Network [OSTI]

    Aggarwal, Suresh K.

    NOx emission characteristics of counterflow syngas diffusion flames with airstream dilution Daniel Abstract Syngas is produced through a gasification process using variety of fossil fuels, including coal. Due to its wide flexibility in fuel sources and superior pollutants characteristics, the syngas

  16. A numerical and experimental study of counterflow syngas flames at different pressures

    E-Print Network [OSTI]

    Aggarwal, Suresh K.

    A numerical and experimental study of counterflow syngas flames at different pressures S. Som, A Synthesis gas or ``Syngas'' is being recognized as a viable energy source worldwide, particularly. There are, however, gaps in the fundamental understanding of syngas combustion and emissions characteristics

  17. Copyright 2007 by ASME1 Laminar Flame Speeds and Strain Sensitivities of Mixtures of H2

    E-Print Network [OSTI]

    Seitzman, Jerry M.

    to rich. [Keywords: Syngas, laminar flame speed, reactant preheat, CO2 dilution, N2 dilution] INTRODUCTION emissions. Synthetic gas (syngas) fuels derived from coal are particularly promising in this regard. Syngas, provides a significant barrier to syngas usage. Understanding the impact of this variability on combustor

  18. Development of an Experimental Facility for Flame Speed Measurements in Powdered Aerosols

    E-Print Network [OSTI]

    Vissotski, Andrew John

    2012-10-19T23:59:59.000Z

    with both dispersion techniques, a pure dust-air system would not ignite due to the current spark ignition system. Thus, a hybrid mixture of Al/CH4/O2/N2 was employed to achieve the project goal of demonstrating a system for controlled laminar flame speed...

  19. Kinetic effects of non-equilibrium plasma-assisted methane oxidation on diffusion flame extinction limits

    E-Print Network [OSTI]

    Ju, Yiguang

    08544, USA b US Air Force Research Laboratory, Propulsion Directorate, Wright-Patterson AFB, OH 45433 plasma assisted combustion resulted in fast chemical heat release and extended the extinction limits processes in plasma­flame interactions [1­17]. However, plasma assisted combustion involves strong coupling

  20. Effects of Lewis number and ignition energy on the determination of laminar flame speed

    E-Print Network [OSTI]

    Ju, Yiguang

    , it affects the fuel burning rate in internal combustion engines and the engine's performance and emissions Engineering, Princeton University, Princeton, NJ 08544, USA Abstract The trajectories of outwardly propagating. Published by Elsevier Inc. on behalf of The Combustion Institute. Keywords: Laminar flame speed; Spherical

  1. Finite-rate chemistry and transient effects in Direct Numerical Simulations of turbulent non-premixed flames

    SciTech Connect (OSTI)

    Mahalingam, S. [Colorado Univ., Boulder, CO (United States). Dept. of Mechanical Engineering; Chen, J.H. [Sandia National Labs., Livermore, CA (United States); Vervisch, L. [Institut de Mecanique des Fluides, Numeriques (France)

    1994-01-01T23:59:59.000Z

    Three-dimensional Direct Numerical Simulations (DNS) of turbulent non-premixed flames including finite-rate chemistry and heat release effects were performed. Two chemical reaction models were considered: (1) a single-step global reaction model in which the heat release and activation energy parameters are chosen to model methane-air combustion, and (2) a two-step reaction model to simulate radical production and consumption and to compare against the single-step model. The model problem consists of the interaction between an initially unstrained laminar diffusion flame and a three-dimensional field of homogeneous turbulence. Conditions ranging from fast chemistry to the pure mixing limit were studied by varying a global Damkoehler number. Results suggest that turbulence-induced mixing acting along the stoichiometric line leads to a strong modification of the inner structure of the turbulent flame compared with a laminar strained flame, resulting in intermediate species concentrations well above the laminar prediction. This result is consistent with experimental observations. Comparison of the response of the turbulent flame structure due to changes in the scalar dissipation rate with a steady strained laminar flame reveals that unsteady strain rates experienced by the turbulent flame may be responsible for the observed high concentrations of reaction intermediates.

  2. 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)

    2010-12-15T23:59:59.000Z

    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)

  3. Radiative properties of char, fly-ash, and soot particles in coal flames. Technical progress report, December 15, 1994--March 30, 1995

    SciTech Connect (OSTI)

    Menguec, M.P.; Manickavasagam, S.; Govindan, R.; Ghosal, S.

    1996-03-01T23:59:59.000Z

    In this paper we present a methodology for measuring the elements of the Mueller (Scattering) matrix, which in turn can be used to determine the size of soot monomers and agglomerates in flames. The experimental system to be used is composed of two linear polarizers, two quarter wave plates and a half wave plate along with a light source (Nd:YAG Laser). The preliminary independent parameters in this setup are the polarizer angles {xi}{sub 1}, {xi}{sub 2} and the retarder angles {beta}{sub 1}, {beta}{sub 2} and {beta}{sub 3}, which can be varied to obtain different condition numbers (CN). If the CN is large, then the Mueller matrix elements determined from experiments would not be reliable. However by using a proper set of {xi} and {beta} values, one can reduce the CN to be less than 10. This concept is discussed for different fractal-like soot agglomerates. It is shown that even if there is {+-}7.5% error in measured intensities, the recovered S{sub 11} and S{sub 12} elements are virtually identical to the true values. These S{sub ij} elements can be used in an inverse algorithm to identify the size of soot monomers and agglomerates.

  4. Virtual Laboratory for Technology For Fusion Energy Science

    E-Print Network [OSTI]

    VLT Virtual Laboratory for Technology For Fusion Energy Science Stan Milora, ORNL Director, Virtual and ITER #12;VLT Virtual Laboratory for Technology For Fusion Energy Science The Technology Program Virtual Laboratory for Technology For Fusion Energy Science The VLT is the steward of burning plasma

  5. Interaction Techniques with Virtual Humans in Mixed Environments

    E-Print Network [OSTI]

    Kallmann, Marcelo

    animation have led to the integration of Virtual Humans [9] into interactive 3D environments. With emergeInteraction Techniques with Virtual Humans in Mixed Environments Selim Balcisoy, Marcelo Kallmann use virtual humans as mediators between the real and virtual world. Keywords: Interaction Techniques

  6. Physical characterization of laminar spray flames in the pressure range 0.1-0.9 MPa

    SciTech Connect (OSTI)

    Russo, Stefano; Gomez, Alessandro [Yale Center for Combustion Studies, Department of Mechanical Engineering, Yale University, P.O. Box 208286, New Haven, CT 06520-8286 (United States)

    2006-04-15T23:59:59.000Z

    An experimental study is reported on the physical characterization of the structure of ethanol/argon/oxygen coflow laminar spray diffusion flames in the pressure range 0.1-0.9 MPa. Diagnostic techniques include phase Doppler anemometry to measure the droplet size distribution and the axial and radial velocity components of the droplets. The gas-phase velocity is determined using measurements from the smallest (low Stokes number) droplets and is corrected for thermophoretic effects. Temperature information is obtained using thin-film pyrometry combined with an infrared camera. All flames present a cold inner core, in which little or no vaporization takes place, surrounded by an envelope flame buried in a thermal boundary layer, where most of the droplet evaporation occurs. The thickness of this thermal boundary layer scales with the inverse of the Peclet number. Especially near the base of the flame, photographic evidence of streaks, which in some case even reveal the presence of soot, suggests that some droplets survive the common envelope flame and burn isolated on the oxidizer side in a mixed regime of internal/external group combustion. The reconstruction of the entire droplet vaporization history confirms this evidence quantitatively. A criterion for droplet survival beyond the envelope flame based on the critical value of a suitably defined vaporization Damkohler number is proposed. The scaling and self-similar behavior of the investigated flames suggest that a mixed regime is established, with a momentum-controlled cold core and a buoyancy-controlled high-temperature boundary layer, the thickness of which varies significantly with pressure, as expected from Peclet number scaling. The growth of this layer and the thickness of the vaporization region are reduced at pressures above atmospheric because of density effects on thermal diffusivity. Some aspects of the design of the combustion chamber and of the atomizer system are discussed in detail since they are critical to the suppression of instabilities and to the establishment of a well-defined high-pressure quasi-steady laminar environment. (author)

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

    SciTech Connect (OSTI)

    Pickett, L; Siebers, D

    2003-08-24T23:59:59.000Z

    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.

  8. Radiation turbulence interactions in pulverized coal flames. Technical progress report, third year, second quarter, December 15, 1995--March 15, 1996

    SciTech Connect (OSTI)

    Menguec, M.P.; McDonough, J.M.; Manickavasagam, S.; Mukerji, S.; Swabb, S.; Ghosal, S.

    1996-09-01T23:59:59.000Z

    In this paper, the authors discuss an experimental and theoretical methodology to characterize soot volume fraction fluctuations in turbulent diffusion flames via chaotic maps. The approach is based on the hypothesis that the fluctuations of properties in turbulent flames is deterministic in nature, rather than statistical. To this extent, the authors measured the time series of soot scattering coefficient in an ethylene diffusion flame from light scattering experiments. Following this, corresponding power spectra and delay maps were calculated. It was shown that if the data were averaged, the characteristics of the fluctuations were almost completely washed out. The psds from experiments were successfully modeled using a series of logistic maps.

  9. Multicomponent aerosol dynamic of the Pb-O[sub 2] system in a bench scale flame incinerator

    SciTech Connect (OSTI)

    Lin, W.Y.; Sethi, V.; Biswas, P.

    1992-01-01T23:59:59.000Z

    The article gives results of a study to understand the formation and growth of lead particles in a flame incinerator. A bench scale flame incinerator was used to perform controlled experiments with lead acetate as a test compound. A dilution probe (in conjunction with real-time aerosol instruments) was used to measure the evolution of the particle size distribution at different locations in the flame region. A multicomponent lognormal aerosol model was developed accounting for the chemistry of the lead-oxygen system, and for such aerosol dynamic phenomena as nucleation, coagulation, and condensation. Reasonable agreement was obtained between the predictions of the model using appropriate kinetic parameters and the experimental results.

  10. National Energy Literacy Virtual Town Hall

    Broader source: Energy.gov [DOE]

    The webinar will be a dynamic, virtual conversation for educators about ongoing efforts from across the country in utilizing the Department of Energy's Energy Literacy Framework to address one of our nation's’ biggest national challenges, energy illiteracy.

  11. Robotics virtual rail system and method

    DOE Patents [OSTI]

    Bruemmer, David J. (Idaho Falls, ID); Few, Douglas A. (Idaho Falls, ID); Walton, Miles C. (Idaho Falls, ID)

    2011-07-05T23:59:59.000Z

    A virtual track or rail system and method is described for execution by a robot. A user, through a user interface, generates a desired path comprised of at least one segment representative of the virtual track for the robot. Start and end points are assigned to the desired path and velocities are also associated with each of the at least one segment of the desired path. A waypoint file is generated including positions along the virtual track representing the desired path with the positions beginning from the start point to the end point including the velocities of each of the at least one segment. The waypoint file is sent to the robot for traversing along the virtual track.

  12. BioenergizeME Virtual Science Fair: Bioenergy

    Broader source: Energy.gov [DOE]

    This infographic was created by students from Sun Valley High School in Aston, PA, as part of the U.S. Department of Energy-BioenergizeME Virtual Science Fair.

  13. QED radiative corrections to virtual Compton scattering

    E-Print Network [OSTI]

    M. Vanderhaeghen; J. M. Friedrich; D. Lhuillier; D. Marchand; L. Van Hoorebeke; J. Van de Wiele

    2000-01-12T23:59:59.000Z

    The QED radiative corrections to virtual Compton scattering (reaction $e p \\to e p \\gamma$) are calculated to first order in $\\alpha_{em} \\equiv e^2 / 4 \\pi$. A detailed study is presented for the one-loop virtual corrections and for the first order soft-photon emission contributions. Furthermore, a full numerical calculation is given for the radiative tail, corresponding with photon emission processes, where the photon energy is not very small compared with the lepton momenta. We compare our results with existing works on elastic electron-proton scattering, and show for the $e p \\to e p \\gamma$ reaction how the observables are modified due to these first order QED radiative corrections. We show results for both unpolarized and polarized observables of the virtual Compton scattering in the low energy region (where one is sensitive to the generalized polarizabilities of the nucleon), as well as for the deeply virtual Compton scattering.

  14. Heavy Ion Fusion Science Virtual National Laboratory

    E-Print Network [OSTI]

    progress with more modest near-term budgets. #12;Slide 5 Heavy Ion Fusion Science Virtual National requirement: modest growth of HIFS-VNL budget from present 7.7 M$/yr to ~16M$/yr, including suppo

  15. Virtual tour: INL's space battery facility

    SciTech Connect (OSTI)

    Johnson, Steve

    2011-01-01T23:59:59.000Z

    This virtual tour shows how INL fuels and tests nuclear power systems for deep space missions. To learn more about INL's contribution to the Mars Science Laboratory, visit http://www.inl.gov/marsrover.

  16. Virtual tour: INL's space battery facility

    ScienceCinema (OSTI)

    Johnson, Steve

    2013-05-28T23:59:59.000Z

    This virtual tour shows how INL fuels and tests nuclear power systems for deep space missions. To learn more about INL's contribution to the Mars Science Laboratory, visit http://www.inl.gov/marsrover.

  17. Balanced Virtual Humans Interacting with their Environment

    E-Print Network [OSTI]

    Rennuit, Antoine; Merlhiot, Xavier; Andriot, Claude; Guillaume, François; Chevassus, Nicolas; Chablat, Damien; Chedmail, Patrick

    2007-01-01T23:59:59.000Z

    The animation of human avatars seems very successful; the computer graphics industry shows outstanding results in films everyday, the game industry achieves exploits... Nevertheless, the animation and control processes of such manikins are very painful. It takes days to a specialist to build such animated sequences, and it is not adaptive to any type of modifications. Our main purpose is the virtual human for engineering, especially virtual prototyping. As for this domain of activity, such amounts of time are prohibitive.

  18. The effects of strain rate and curvature on surface density function transport in turbulent premixed methane-air and hydrogen-air flames: A comparative study

    SciTech Connect (OSTI)

    Chakraborty, N. [Engineering Department, University of Liverpool, Brownlow Hill, Liverpool L69 3GH (United Kingdom); Hawkes, E.R. [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Chen, J.H. [Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551 (United States); Cant, R.S. [Engineering Department, Cambridge University, Trumpington Street, Cambridge CB2 1PZ (United Kingdom)

    2008-07-15T23:59:59.000Z

    The effects of tangential strain rate and curvature on the surface density function (SDF) and on source terms within the SDF transport equation are studied for lean methane-air and hydrogen-air flames using two-dimensional direct numerical simulations with detailed chemistry. A positive correlation is observed between the SDF and the tangential strain rate, and this is explained in terms of the interaction between the local tangential strain rate and the dilatation rate due to heat release. Curvature is also seen to affect the SDF through the curvature response of both tangential strain rate and dilatation rate on a given flame isosurface. Strain rate and curvature are found to have an appreciable effect on several terms of the SDF transport equation. The SDF straining term in both methane and hydrogen flames is correlated positively with tangential strain rate, as expected, and is also correlated negatively with curvature. For methane flames, the SDF propagation term is found to correlate negatively with flame curvature toward the reactant side of the flame and positively toward the product side. By contrast, for hydrogen flames the SDF propagation term is negatively correlated with curvature throughout the flame brush. The variation of the SDF curvature term with local flame curvature for both methane and hydrogen flames is found to be nonlinear due to the additional stretch induced by the tangential diffusion component of the displacement speed. Physical explanations are provided for all of these effects, and the modeling implications are considered in detail. (author)

  19. Radiation-turbulence interactions in pulverized-coal flames. Quarterly report No. III, March 15, 1994--June 15, 1994

    SciTech Connect (OSTI)

    Menguec, M.P.; McDonough, J.M.

    1994-09-01T23:59:59.000Z

    The work concerns the development of computer codes for the simulation of radiation turbulence interactions in coal flames. Experimental studies in tandem with the turbulence calculations are based on optical observation of scattered light from coal particles under combustion conditions.

  20. 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 ...

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

    E-Print Network [OSTI]

    Grcar, Joseph F

    2008-01-01T23:59:59.000Z

    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

  2. Investigation of the Difference in Cool Flame Characteristics between Petroleum Diesel and Soybean Biodiesel Operating in Low Temperature Combustion Mode

    E-Print Network [OSTI]

    Muthu Narayanan, Aditya

    2014-01-16T23:59:59.000Z

    . The focus of this study is to investigate the difference in the cool flame combustion characteristics between petroleum diesel and soybean biodiesel, when operating in low temperature combustion mode. Previous studies have attributed the absence of the cool...

  3. Haptic Rendering of Parametric Surfaces Using a Feedback Stabilized Extremal Distance Tracking Algorithm

    E-Print Network [OSTI]

    Gillespie, Brent

    Haptic Rendering of Parametric Surfaces Using a Feedback Stabilized Extremal Distance Tracking rendering. 1. Introduction Haptic rendering is the process by which virtual objects are made apparent to be felt and at the same time made available to be manipulated by a human user. Haptic render- ing requires

  4. Haptic Rendering of Parametric Surfaces Using a Feedback Stabilized Extremal Distance Tracking Algorithm

    E-Print Network [OSTI]

    Gillespie, Brent

    1 Haptic Rendering of Parametric Surfaces Using a Feedback Stabilized Extremal Distance Tracking representation of haptic rendering. Haptic rendering is the process by which virtual objects are made apparent to be felt and at the same time made available to be manipulated by a human user. Haptic rendering requires

  5. Longitudinal Stability Calculations

    SciTech Connect (OSTI)

    Blaskiewicz,M.

    2009-01-02T23:59:59.000Z

    Coupled bunch longitudinal stability in the presence of high frequency impedances is considered. A frequency domain technique is developed and compared with simulations. The frequency domain technique allows for absolute stability tests and is applied to the problem of longitudinal stability in RHIC with the new 56 MHz RF system.

  6. Apparatus and method for stabilization or oxidation of polymeric materials

    DOE Patents [OSTI]

    Paulauskas, Felix L. (Knoxville, TN) [Knoxville, TN; Sherman, Daniel M. (Knoxville, TN) [Knoxville, TN

    2010-01-19T23:59:59.000Z

    An apparatus for treating polymeric materials comprises a treatment chamber adapted to maintain a selected atmosphere at a selected temperature; a means for supporting the polymeric material within the chamber; and, a source of ozone-containing gas, which decomposes at the selected temperature yielding at least one reactive oxidative species whereby the polymer is stabilized and cross linked through exposure to the oxidative species in the chamber at the selected temperature. The ozone may be generated by a plasma discharge or by various chemical processes. The apparatus may be configured for either batch-type or continuous-type processing. The apparatus and method are especially useful for preparing polymer fibers, particularly PAN fibers, for later carbonization treatments as well as to make flame-retardant fabrics.

  7. Motion Capture Based Animation for Virtual Human Demonstrators: Modeling, Parameterization and Planning

    E-Print Network [OSTI]

    Huang, Yazhou

    2012-01-01T23:59:59.000Z

    sive gaze animation for virtual humans. ” In Proceedings ofCapture Based Animation for Virtual Human Demonstrators:Capture Based Animation for Virtual Human Demonstrators:

  8. Army Virtual Housing Experience The Army virtual housing experience provides Soldiers and Families world class

    E-Print Network [OSTI]

    US Army Corps of Engineers

    Army Virtual Housing Experience Fact Sheet OVERVIEW The Army virtual housing experience provides Soldiers and Families world class customer focused housing information which allows them to make informed housing choices regarding off-post, privatized or government housing upon receipt of orders by using

  9. An Architecture for Managing Virtual Circuit and Virtual Path Services on ATM Networks

    E-Print Network [OSTI]

    Columbia University

    1 An Architecture for Managing Virtual Circuit and Virtual Path Services on ATM Networks Abstract management architecture that provides the services and is instrumented for network management purposes service monitor- ing and control functions. The network management architecture proposes complete managed

  10. Isis essay review 1 P. N. Edwards Virtual Machines, Virtual Infrastructures

    E-Print Network [OSTI]

    Edwards, Paul N.

    Isis essay review 1 P. N. Edwards Virtual Machines, Virtual Infrastructures: The New Historiography of Information Technology Published in Isis, 1998 Review of: Campbell-Kelly, Martin; Aspray, William. Computer and the author of many books on computer history, including three #12;Isis essay review 2 P. N. Edwards

  11. July 2012July 2012 Cloud Computing and Virtualization:Cloud Computing and Virtualization

    E-Print Network [OSTI]

    Liu, Jiangchuan (JC)

    July 2012July 2012 Cloud Computing and Virtualization:Cloud Computing and Virtualization/26/2633 Recent: CloudRecent: Cloud The fast growth of cloud computing Cloud file storage/synchronization services Google entries about cloud computing: 184,000,000 #12;July 2012July 2012 44/26/2644 Our CloudOur Cloud 7

  12. 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. [Department of Chemical Engineering, University of Utah, Salt Lake City, UT (United States); D'Anna, Andrea [Dipartimento di Ingegneria Chimica, Universita ''Federico II'' di Napoli, Naples (Italy)

    2011-01-15T23:59:59.000Z

    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)

  13. Investigation of the processes controlling the flame generation of refractory materials. Progress report, July 1, 1991--June 30, 1992

    SciTech Connect (OSTI)

    Katz, J.L.

    1992-01-01T23:59:59.000Z

    The processes involved in the formation of mixed oxides powders were studied using the counterflow diffusion flame burner. Powders of different morphologies were obtained by varying the flame conditions (temperature, residence time) and the concentration ratio of the oxides precursors. In-situ particle size and number density were determined using dynamic light scattering and 90{degrees} light scattering. A thermophoretic sampling method and a larger scale powder collection device also was used to collect particles, and their size and morphology examined using transmission electron microscopy, X-ray diffraction and surface area measurement by gas absorption (BET). Our emphasis has been on TiO{sub 2}-SiO{sub 2}, SiO{sub 2}-GeO{sub 2} and Al{sub 2}O{sub 3}-TiO{sub 2}. The powders had a core-mantle-like (one oxide coated by the other) at low elevations in the burner and uniform mixture at higher elevations. They form chain-like structures in a low temperature flame and spherical particles in a higher temperature flame. Nanometer sized homogeneous particles of Aluminum Titanate could be obtained using Al(CH{sub 3}){sub 3} and TiCl{sub 4} as precursors both in a hydrogen fueled and a methane fueled counterflow diffusion flame burner, as well as in a hydrogen fueled parallel-flow diffusion flame burner.

  14. Experimental study on thermophoretic deposition of soot particles in laminar diffusion flames along a solid wall in microgravity

    SciTech Connect (OSTI)

    Choi, Jae-Hyuk; Chung, Suk Ho [School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742 (Korea); Fujita, Osamu; Tsuiki, Takafumi [Division of Mechanical and Space Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Kim, Junhong [Laboratoire E.M2.C., UPR 288 C.N.R.S Ecole Centrale Paris, Grande Voie des Vignes 92295 (France)

    2008-09-15T23:59:59.000Z

    Soot deposition process in diffusion flames along a solid wall has been investigated experimentally under a microgravity environment. An ethylene (C{sub 2}H{sub 4}) diffusion flame was formed around a cylindrical rod-burner with the surrounding air velocities of V{sub a} = 2.5, 5, and 10 cm/s, the oxygen concentration of 35%, and the burner wall temperature of 300 K. A laser extinction method was adopted to measure the distribution of soot volume fraction. The experiments determined the trace of maximum soot concentration together with the relative distance of the trace of flame. Results showed that the distance was about 2-5 mm. As the surrounding air velocity increased, the region of the soot particle distribution moved closer to the burner wall. The soot particles near the flame zone tended to move away from the flame zone because of the thermophoretic force and to concentrate at a certain narrow region inside the flame. Because of the simultaneous effects of convection and the thermophoresis, soot particles finally adhered to the burner wall. It has been found that there existed an optimal air velocity for the early deposition of soot on the furnace wall. (author)

  15. Physical and chemical comparison of soot in hydrocarbon and biodiesel fuel diffusion flames: A study of model and commercial fuels

    SciTech Connect (OSTI)

    Matti Maricq, M. [Research and Advanced Engineering, Ford Motor Company, Dearborn, MI (United States)

    2011-01-15T23:59:59.000Z

    Data are presented to compare soot formation in both surrogate and practical fatty acid methyl ester biodiesel and petroleum fuel diffusion flames. The approach here uses differential mobility analysis to follow the size distributions and electrical charge of soot particles as they evolve in the flame, and laser ablation particle mass spectrometry to elucidate their composition. Qualitatively, these soot properties exhibit a remarkably similar development along the flames. The size distributions begin as a single mode of precursor nanoparticles, evolve through a bimodal phase marking the onset of aggregate formation, and end in a self preserving mode of fractal-like particles. Both biodiesel and hydrocarbon fuels yield a common soot composition dominated by C{sub x}H{sub y}{sup +} ions, stabilomer PAHs, and fullerenes in the positive ion mass spectrum, and C{sub x}{sup -} and C{sub 2x}H{sup -} in the negative ion spectrum. These ion intensities initially grow with height in the diffusion flames, but then decline during later stages, consistent with soot carbonization. There are important quantitative differences between fuels. The surrogate biodiesel fuel methyl butanoate substantially reduces soot levels, but soot formation and evolution in this flame are delayed relative to both soy and petroleum fuels. In contrast, soots from soy and hexadecane flames exhibit nearly quantitative agreement in their size distribution and composition profiles with height, suggesting similar soot precursor chemistry. (author)

  16. Tritium systems test assembly stabilization

    SciTech Connect (OSTI)

    Jasen, W. G. (William G.); Michelotti, R. A. (Roy A.); Anast, K. R. (Kurt R.); Tesch, Charles

    2004-01-01T23:59:59.000Z

    The Tritium Systems Test Assembly (TSTA) was a facility dedicated to tritium technology Research and Development (R&D) primarily for future fusion power reactors. The facility was conceived in mid 1970's, operations commenced in early 1980's, stabilization and deactivation began in 2000 and were completed in 2003. The facility will remain in a Surveillance and Maintenance (S&M) mode until the Department of Energy (DOE) funds demolition of the facility, tentatively in 2009. A safe and stable end state was achieved by the TSTA Facility Stabilization Project (TFSP) in anticipation of long term S&M. At the start of the stabilization project, with an inventory of approximately 140 grams of tritium, the facility was designated a Hazard Category (HC) 2 Non-Reactor Nuclear facility as defined by US Department of Energy standard DOE-STD-1027-92 (1997). The TSTA facility comprises a laboratory area, supporting rooms, offices and associated laboratory space that included more than 20 major tritium handling systems. The project's focus was to reduce the tritium inventory by removing bulk tritium, tritiated water wastes, and tritium-contaminated high-inventory components. Any equipment that remained in the facility was stabilized in place. All of the gloveboxes and piping were rendered inoperative and vented to atmosphere. All equipment, and inventoried tritium contamination, remaining in the facility was left in a safe-and-stable state. The project used the End Points process as defined by the DOE Office of Environmental Management (web page http://www.em.doe.- gov/deact/epman.htmtlo) document and define the end state required for the stabilization of TSTA Facility. The End Points process added structure that was beneficial through virtually all phases of the project. At completion of the facility stabilization project the residual tritium inventory was approximately 3,000 curies, considerably less than the 1.6-gram threshold for a HC 3 facility. TSTA is now designated as a Radiological Facility. Innovative approaches were employed for characterization and removal of legacy wastes and high inventory components. Major accomplishments included: (1) Reduction of tritium inventory, elimination of chemical hazards, and identification and posting of remaining hazards. (2) Removal of legacy wastes. (3) Transferred equipment for reuse in other DOE projects, including some at other DOE facilities. (4) Transferred facility in a safe and stable condition to the S&M organization. The project successfully completed all project goals and the TSTA facility was transferred into S&M on August 1,2003. This project demonstrates the benefit of radiological inventory reduction and the removal of legacy wastes to achieve a safe and stable end state that protects workers and the environment pending eventual demolition of the facility.

  17. Investigation of the flame speeds of propane/methanol gas mixtures

    SciTech Connect (OSTI)

    Foote, K.L.; Villareal, J.

    1985-05-02T23:59:59.000Z

    A series of tests was conducted in an acoustically tuned flame tube in order to determine the laminar burning velocities in air of various propane/methanol gas mixtures. The experimental method is explained in detail, along with the tabular results. A 90% propane, 10% methanol mixture is shown to have a maximum burning velocity of 40.8 cm/s. A 65% propane, 35% methanol mixture has a maximum velocity of 41.8 cm/s. These maximum flame speeds are shown to be about the same as that of pure propane by the same method. Gulder has found evidence that the presence of methanol in some hydrocarbon fuels may actually inhibit combustion, but we see no apparent modifications in the combustion of propane when mixed with methanol.

  18. Second Law Comparisons of Volumetric and Flame Combustion in an Ideal Engine with Exhaust Heat Recovery

    SciTech Connect (OSTI)

    Chakravarthy, Veerathu K [ORNL; Daw, C Stuart [ORNL; Graves, Ronald L [ORNL

    2006-01-01T23:59:59.000Z

    We summarize the results of a theoretical second law (exergy) analysis of an idealized internal combustion engine operating in flame versus volumetric (e.g., HCCI-like) combustion modes. We also consider the impact of exhaust heat recovery. Our primary objective is to better understand the fundamental differences (if any) in thermodynamic irreversibility among these different combustion modes and the resulting impact on engine work output. By combustion irreversibility, we mean that portion of the fuel energy that becomes unavailable for producing useful work due to entropy generation in the combustion process, exclusive of all other heat and friction losses. A key question is whether or not volumetric combustion offers any significant irreversibility advantage over conventional flame combustion. Another key issue is how exhaust heat recovery would be expected to change the net work output of an ideal piston engine. Based on these results, we recommend specific research directions for improving the fuel efficiency of advanced engines.

  19. The oxidation of soot and carbon monoxide in hydrocarbon diffusion flames

    SciTech Connect (OSTI)

    Puri, R.; Santoro, R.J. (Pennsylvania State Univ., University Park, PA (United States). Dept. of Mechanical Engineering); Smyth, K.C. (National Inst. of Standards and Technology, Gaithersburg, MD (United States). Building and Fire Research Lab.)

    1994-05-01T23:59:59.000Z

    Quantitative hydroxyl radical concentrations and primary soot particle sizes have been determined in the soot oxidation regions of axisymmetric diffusion flames burning methane, methane/butane, and methane/1-butene in air at atmospheric pressure. The total carbon flow rate was held constant in these flames while the maximum amount of soot varied by a factor of seven along the centerline. Laser-induced fluorescence measurements of OH were placed on an absolute basis by calibration against earlier absorption results. The primary size measurements of the soot particles were made using thermophoretic sampling and transmission electron microscopy. OH concentrations are greatly reduced in the presence of soot particles. Whereas large super-equilibrium ratios are observed in the high-temperature reaction zones in the absence of soot, the OH concentrations approach equilibrium values when the soot loading is high. The diminished OH concentrations are found to arise from reactions with the soot particles and only to a minor degree from lower temperatures due to soot radiation losses. Analysis of the soot oxidation rates computed from the primary particle size profiles as a function of time along the flame centerlines shows that OH is the dominant oxidizer of soot, with O[sub 2] making only a small contribution. Higher collision efficiencies of OH reactions with soot particles are found for the flames containing larger soot concentrations at lower temperatures. A comparison of the soot and CO oxidation rates shows that although CO is inherently more reactive than soot, the soot successfully competes with CO for OH and hence suppresses CO oxidation for large soot concentrations.

  20. Soot formation in weakly buoyant acetylene-fueled laminar jet diffusion flames burning in air

    SciTech Connect (OSTI)

    Sunderland, P.B.; Koeylue, U.O.; Faeth, G.M. (Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Aerospace Engineering)

    1995-01-01T23:59:59.000Z

    The structure and soot properties of weakly buoyant, acetylene-fueled, laminar jet diffusion flames were studied experimentally for combustion in air at pressures of 0.125--0.250 atm. The following measurements were made: soot volume fractions using laser extinction, temperatures using both thermocouples and multiline emission, soot structure using thermophoretic sampling and analysis by transmission electron microscopy, concentrations of major gas species using sampling and analysis by gas chromatography, and velocities using laser velocimetry. As distance increased along the axis of the present acetylene-fueled flames, significant soot formation began when temperatures exceeded roughly 1250 K, and ended when fuel-equivalence ratios decreased to roughly 1.7, where the concentration of acetylene became small. This behavior allowed observations of soot growth and nucleation for acetylene concentrations of 6 [times] 10[sup [minus]6]--1 [times] 10[sup [minus]3] and temperatures of 1,000--2,100 K. Over this range of conditions, soot growth rates were comparable to past observations of new soot in premixed flames, and after correction for effects of soot oxidation yielded essentially first-order growth with respect to acetylene concentrations with a negligible activation energy, and an acetylene/soot collision efficiency of 0.53%. Present measurements of soot nucleation rates also suggested first-order behavior with respect to acetylene concentrations but with an activation energy of 32 kcal/gmol and with rates that were significantly lower than earlier estimates in the literature. Nevertheless, uncertainties about the effects of soot oxidation and age on soot growth, and about effects of surface area estimates and translucent objects on soot nucleation, must be resolved in order to adequately define soot formation processes in diffusion flames.

  1. The use of particle tracking to obtain planar velocity measurements in an unsteady laminar diffusion flame

    SciTech Connect (OSTI)

    Lewis, G.S.; Cantwell, B.J.; Lecuona, A.

    1987-01-01T23:59:59.000Z

    An investigation of the flame-flow interaction in an unsteady laminar co-flowing jet diffusion flame is underway. The flame is made periodic by acoustic excitation of the fuel stream. The objective of the research is to develop a better understanding of the relationship between the flowfield and combustion process by superimposing measurements of the vector velocity field on planar measurements of reactive and passive scalars. In this connection a technique is being developed to obtain instantaneous two-dimensional velocity measurements from multiply-exposed photographic images of scattered light from speed particles in the flow. The technique involves simple photographic images taken at a right angle to a thin laser sheet on the diametric center of the jet. The illumination source is pulsed Cu vapor laser. The important issues considered have included the particle type and size as they relate to the particle's ability to follow the flow and to withstand combustion temperatures. Also of concern is the effect of thermophoretic forces on the measurement accuracy. Both Al/sub 2/O/sub 3/ and TiO/sub 2/ have been used successfully and detailed information about the size and geometry of TiO/sub 2/ particles has been obtained through scanning electron microscope photographs. The TiO/sub 2/ particles have been produced from the reaction of TiCl/sub 4/ and water. The technique has been successfully demonstrated by measuring a cold laminar jet exit velocity profile. Also, good particle images have been obtained in a pulsed diffusion flame.

  2. Temperature of aircraft cargo flame exposure during accidents involving fuel spills

    SciTech Connect (OSTI)

    Mansfield, J.A.

    1993-01-01T23:59:59.000Z

    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.

  3. The influence of initial temperature on flame acceleration and deflagration-to-detonation transition

    SciTech Connect (OSTI)

    Ciccarelli, G.; Boccio, J.L.; Ginsberg, T. [and others

    1996-07-01T23:59:59.000Z

    The influence of initial mixture temperature on deflagration-to-detonation transition (DDT) has been investigated experimentally. The experiments were carried out in a 27-cm-inner diameter, 21.3-meter-long heated detonation tube, which was equipped with periodic orifice plates to promote flame acceleration. Hydrogen-air-steam mixtures were tested at a range of temperatures up to 650K and at an initial pressure of 0.1 MPa. In most cases, the limiting hydrogen mole fraction which resulted in transition to detonation corresponded to the mixture whose detonation cell size, {lambda}, was approximately equal to the inner diameter of the orifice plate, d (e.g., d/{lambda}{approximately}1). The only exception was in dry hydrogen-air mixtures at 650K where the DDT limit was observed to be 11 percent hydrogen, corresponding to a value of d/{lambda} equal to 5.5. For a 10.5 percent hydrogen mixture at 650K, the flame accelerated to a maximum velocity of about 120 m/s and then decelerated to below 2 m/s. This observation indicates that the d/{lambda} = 1 DDT limit criterion provides a necessary condition but not a sufficient one for the onset of DDT in obstacle-laden ducts. In this particular case, the mixture initial condition (i.e., temperature) resulted in the inability of the mixture to sustain flame acceleration to the point where DDT could occur. It was also observed that the distance required for the flame to accelerate to the onset of detonation was a function of both the hydrogen mole fraction and the mixture initial temperature. For example, decreasing the hydrogen mole fraction or increasing the initial mixture temperature resulted in longer transition distances.

  4. 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

    2010-12-12T23:59:59.000Z

    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.

  5. Large eddy simulation of soot formation in a turbulent non-premixed jet flame

    SciTech Connect (OSTI)

    El-Asrag, Hossam [Center For Turbulence Research, Stanford, CA 94305 (United States); Menon, Suresh [School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States)

    2009-02-15T23:59:59.000Z

    A recently developed subgrid model for soot dynamics [H. El-Asrag, T. Lu, C.K. Law, S. Menon, Combust. Flame 150 (2007) 108-126] is used to study the soot formation in a non-premixed turbulent flame. The model allows coupling between reaction, diffusion and soot (including soot diffusion and thermophoretic forces) processes in the subgrid domain without requiring ad hoc filtering or model parameter adjustments. The combined model includes the entire process, from the initial phase, when the soot nucleus diameter is much smaller than the mean free path, to the final phase, after coagulation and aggregation, where it can be considered in the continuum regime. A relatively detailed but reduced kinetics for ethylene-air is used to simulate an experimentally studied non-premixed ethylene/air jet diffusion flame. Acetylene is used as a soot precursor species. The soot volume fraction order of magnitude, the location of its maxima, and the soot particle size distribution are all captured reasonably. Along the centerline, an initial region dominated by nucleation and surface growth is established followed by an oxidation region. The diffusion effect is found to be most important in the nucleation regime, while the thermophoretic forces become more influential downstream of the potential core in the oxidation zone. The particle size distribution shows a log-normal distribution in the nucleation region, and a more Gaussian like distribution further downstream. Limitations of the current approach and possible solution strategies are also discussed. (author)

  6. OH and CH luminescence in opposed flow methane oxy-flames

    SciTech Connect (OSTI)

    De Leo, Maurizio; Saveliev, Alexei; Kennedy, Lawrence A. [Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL 60607 (United States); Zelepouga, Serguei A. [Gas Technology Institute, Des Plaines, IL 60018 (United States)

    2007-06-15T23:59:59.000Z

    Emission spectroscopy is a 2-D nonintrusive diagnostic technique that offers spatially resolved data for combustion optimization and control. The UV and visible chemiluminescence of the excited radicals CH(A{sup 2}{delta},B{sup 2}{sigma}{sup -}) and OH(A{sup 2}{sigma}{sup +}) is studied experimentally and numerically in opposed-flow diffusion flames of methane and oxygen-enriched air. The oxidized oxygen content is varied from 21 to 100% while the range of the studied strain rates spans from 20 to 40 s{sup -1}. The spectrally resolved imaging is obtained by two different methods: scattering through a grating monochromator and interposition of interference filters along the optical path. Absolute measured chemiluminescence intensities, coupled with a numerical model based on the opposed flow flame code, are used to evaluate the chemical kinetics of the excited species. The predictions of the selected model are in good agreement with the experimental data over the range of the studied flame conditions. (author)

  7. Rotational effects in thermonuclear Type I Bursts: equatorial crossing and directionality of flame spreading

    E-Print Network [OSTI]

    Cavecchi, Yuri; Levin, Yuri; Braithwaite, Jonathan

    2014-01-01T23:59:59.000Z

    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...

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

    E-Print Network [OSTI]

    Chakraborty, Manoneeta

    2014-01-01T23:59:59.000Z

    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...

  9. Molecular Characterization of Organic Content of Soot along the Centerline of a Coflow Diffusion Flame

    SciTech Connect (OSTI)

    Cain, Jeremy P.; Laskin, Alexander; Kholghy, Mohammad Reza; Thomson, Murray; Wang, Hai

    2014-10-29T23:59:59.000Z

    High-resolution mass spectrometry coupled with nanospray desorption electrospray ionization was used to probe chemical constituents of young soot particles sampled along the centerline of a coflow diffusion flame of a three-component Jet-A1 surrogate. In lower positions where particles are transparent to light extinction (n= 632.8 nm), peri-condensed polycyclic aromatic hydrocarbons (PAHs) are found to be the major components of the particle material. These particles become enriched with aliphatic components as they grow in mass and size. Before carbonization occurs, the constituent species in young soot particles are aliphatic and aromatic compounds 200-600 amu in mass, some of which are oxygenated. Particles dominated by PAHs or mixtures of PAHs and aliphatics can both exhibit liquid-like appearance observed by electron microscopy and be transparent to visible light. The variations in chemical composition observed here indicate that the molecular processes of soot formation in coflow diffusion flames may be more complex than previously thought. For example, the mass growth and enrichment of aliphatic components in an initially, mostly aromatic structure region of the flame that is absent of H atoms or other free radicals indicates that there must exist at least another mechanism of soot mass growth in addition to the hydrogen-abstraction-carbon addition mechanism currently considered in fundamental models of soot formation.

  10. Ion mobility spectrometer with virtual aperture grid

    DOE Patents [OSTI]

    Pfeifer, Kent B. (Los Lunas, NM); Rumpf, Arthur N. (Albuquerque, NM)

    2010-11-23T23:59:59.000Z

    An ion mobility spectrometer does not require a physical aperture grid to prevent premature ion detector response. The last electrodes adjacent to the ion collector (typically the last four or five) have an electrode pitch that is less than the width of the ion swarm and each of the adjacent electrodes is connected to a source of free charge, thereby providing a virtual aperture grid at the end of the drift region that shields the ion collector from the mirror current of the approaching ion swarm. The virtual aperture grid is less complex in assembly and function and is less sensitive to vibrations than the physical aperture grid.

  11. Understanding the Team Dynamics of an Executive Virtual Team

    E-Print Network [OSTI]

    Riley, Ramona Leonard

    2011-10-21T23:59:59.000Z

    employ virtuality in their work regimen. Therefore, organizations employ virtual executives to work teams with ideal skill sets to effectively persevere and complete tasks through distance, space, and time. The purpose of this study was to identify...

  12. Virtual Mentor American Medical Association Journal of Ethics

    E-Print Network [OSTI]

    Fujimura, Joan

    Virtual Mentor American Medical Association Journal of Ethics August 2012, Volume 14, Number 8: 657, such as a particular genetic variant that might be related www.virtualmentor.org Virtual Mentor, August 2012--Vol 14

  13. Exploring Second Life as a beneficial virtual learning environment 

    E-Print Network [OSTI]

    Haisworth, Reissa

    2008-06-27T23:59:59.000Z

    With the growth of the internet comes the development of virtual worlds which create a perfect setting for meeting new people from around the world, chatting to existing friends and learning. Second Life is a virtual world ...

  14. Presence in a Distributed Virtual Environment for Cooperative Visualization

    E-Print Network [OSTI]

    Blake, Edwin

    Presence in a Distributed Virtual Environment for Cooperative Visualization Juan Casanueva of computer networks and computer graphics technology, Collabora- tive Virtual Environments are becoming-Supported Collaborative Work (CSCW). Collaborative Vir- tual Environments involve the use of a distributed architecture

  15. A circumferential slot virtual impactor for bioaerosol concentration

    E-Print Network [OSTI]

    Adams, Clinton Wayne

    2009-05-15T23:59:59.000Z

    A virtual impactor aerosol concentrator with a circumferential inlet slot has been built and tested. Circumferential slot virtual impactors (CSVIs) have low pressure losses, similar to linear slot impactors, but without particle losses due to end...

  16. The Virtual (Re)Construction of History: Some Epistemological Questions

    E-Print Network [OSTI]

    El Antably, Ahmed

    2010-01-01T23:59:59.000Z

    Antably: The Virtual (Re)Construction of History 14. DoreenMay 1, 2010 THE VIRTUAL (RE)CONSTRUCTION OF HISTORY: SOMEthe use of perspectival constructions that emulate everyday

  17. The effect of initial temperature on flame acceleration and deflagration-to-detonation transition phenomenon

    SciTech Connect (OSTI)

    Ciccarelli, G.; Boccio, J.L.; Ginsberg, T.; Finfrock, C.; Gerlach, L. [Brookhaven National Lab., Upton, NY (United States); Tagawa, H. [Nuclear Power Engineering Corp., Tokyo (Japan); Malliakos, A. [Nuclear Regulatory Commission, Washington, DC (United States)

    1998-05-01T23:59:59.000Z

    The High-Temperature Combustion Facility at BNL was used to conduct deflagration-to-detonation transition (DDT) experiments. Periodic orifice plates were installed inside the entire length of the detonation tube in order to promote flame acceleration. The orifice plates are 27.3-cm-outer diameter, which is equivalent to the inner diameter of the tube, and 20.6-cm-inner diameter. The detonation tube length is 21.3-meters long, and the spacing of the orifice plates is one tube diameter. A standard automobile diesel engine glow plug was used to ignite the test mixture at one end of the tube. Hydrogen-air-steam mixtures were tested at a range of temperatures up to 650K and at an initial pressure of 0.1 MPa. In most cases, the limiting hydrogen mole fraction which resulted in DDT corresponded to the mixture whose detonation cell size, {lambda}, was equal to the inner diameter of the orifice plate, d (e.g., d/{lambda}=1). The only exception was in the dry hydrogen-air mixtures at 650K where the DDT limit was observed to be 11 percent hydrogen, corresponding to a value of d/{lambda} equal to 5.5. For a 10.5 percent hydrogen mixture at 650K, the flame accelerated to a maximum velocity of about 120 mIs and then decelerated to below 2 mIs. By maintaining the first 6.1 meters of the vessel at the ignition end at 400K, and the rest of the vessel at 650K, the DDT limit was reduced to 9.5 percent hydrogen (d/{lambda}=4.2). This observation indicates that the d/{lambda}=1 DDT limit criteria provides a necessary condition but not a sufficient one for the onset of DDT in obstacle laden ducts. In this particular case, the mixture initial condition (i.e., temperature) resulted in the inability of the mixture to sustain flame acceleration to the point where DDT could occur. It was also observed that the distance required for the flame to accelerate to the point of detonation initiation, referred to as the run-up distance, was found to be a function of both the hydrogen mole fraction and the mixture initial temperature. Decreasing the hydrogen mole fraction or increasing the initial mixture temperature resulted in longer run-up distances. The density ratio across the flame and the speed of sound in the unburned mixture were found to be two parameters which influence the run-up distance.

  18. 2015 SunShot Incubator Virtual Showcase Slides

    Broader source: Energy.gov [DOE]

    Download the slides from the 2015 SunShot Initiative Incubator Virtual Showcase webinar, which occurred March 4, 2015

  19. auditory virtual environments: Topics by E-print Network

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

    impor- tance Liu, Ling 52 Natural Interaction in Virtual Environments Gabriel Zachmann Computer Technologies and Information Sciences Websites Summary: -environment...

  20. Virtual Clay: Haptics-based Deformable Solids of Arbitrary Topology

    E-Print Network [OSTI]

    McDonnell, Kevin

    Virtual Clay: Haptics-based Deformable Solids of Arbitrary Topology Kevin T. McDonnell and Hong Qin|qin}@cs.sunysb.edu Abstract. This paper presents Virtual Clay as a novel, interactive, dy- namic, haptics-based deformable solid of arbitrary topology. Our Virtual Clay methodology is a unique, powerful visual modeling paradigm

  1. Virtual Compass: Relative Positioning To Sense Mobile Social Interactions

    E-Print Network [OSTI]

    Hunt, Galen

    Virtual Compass: Relative Positioning To Sense Mobile Social Interactions Nilanjan Banerjee in availability and ac- curacy. Virtual Compass is a peer-based relative positioning system that relies solely movement. We have im- plemented Virtual Compass on mobile phones and laptops, and we eval- uate it using

  2. Virtualizing Power Cords by Wireless Power Transmission and Energy Harvesting

    E-Print Network [OSTI]

    Tentzeris, Manos

    technology can be called the virtualization of the communication line, wireless power transmissionVirtualizing Power Cords by Wireless Power Transmission and Energy Harvesting Yoshihiro Kawahara1 for the virtualization of power cords for electrical devices. The first approach is a new concept for routing electric

  3. NIST Special Publication 1173 Virtual Cement and Concrete

    E-Print Network [OSTI]

    #12;NIST Special Publication 1173 Virtual Cement and Concrete Testing Laboratory Version 9.5 User;Virtual Cement and Concrete Testing Laboratory Version 9.5 User Guide Jeffrey W. Bullard1 Materials-8615 This document serves as the user's guide for the Virtual Cement and Con- crete Testing Laboratory (VCCTL

  4. Virtual Laboratory for Technology For Fusion Energy Science

    E-Print Network [OSTI]

    VLT Virtual Laboratory for Technology For Fusion Energy Science Stan Milora, ORNL Director, Virtual for Technology For Fusion Energy Science VLT Research MissionVLT Research Mission To contribute to the national;VLT Virtual Laboratory for Technology For Fusion Energy Science OutlineOutline · VLT contributions

  5. Coevolution Produces an Arms Race Among Virtual Plants

    E-Print Network [OSTI]

    Ebner, Marc

    Coevolution Produces an Arms Race Among Virtual Plants Marc Ebner, Adrian Grigore, Alexander He#11 create plants for a virtual environment. The plants are represented as context-free Lin- denmayer systems. OpenGL is used to visualize and evaluate the plants. Our plants have to collect virtual sunlight

  6. Web Based Simulations for Virtual Scientific Experiment: Methodology and Tools

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    . These are the keywords. Web based simulation, Virtual Scientific Experiment, e-learning 1. INTRODUCTION Until now Technology for Enhanced Learning 1 #12;Web Based Simulations for Virtual Scientific Experiment: MethodologyWeb Based Simulations for Virtual Scientific Experiment: Methodology and Tools Giovannina Albano

  7. Leadership in self-managing virtual teams Kevin Crowston

    E-Print Network [OSTI]

    Crowston, Kevin

    1 Leadership in self-managing virtual teams Kevin Crowston Syracuse University, School acknowledge the contri- butions of Hala Annabi, Chengetai Masango and James Howison. #12;Leadership in self-managing virtual teams Leadership in self-managing virtual teams Abstract In this paper, we present a theory

  8. Towards a Virtual Environment for Interactive World Building

    E-Print Network [OSTI]

    Towards a Virtual Environment for Interactive World Building Dieter Schmalstieg and Michael|gervautz@cg.tuwien.ac.at http://www.cg.tuwien.ac.at/ Abstract We propose an architecture for virtual environments that is aimed and maintenance of the virtual environment. Users can be present in the environment using software clients

  9. The Virtual Stuntman: Dynamic Characters with a Repertoire of

    E-Print Network [OSTI]

    Panne, M. van de

    is applicable and expected to work properly. Key words: Artificial Life, Virtual Humans, Computer Animation considerable progress in animating virtual humans [1,5], physics-based an- imated characters with a large is the creation of virtual actors that autonomously synthesize realistic human motions and possess a broad

  10. CREATING 3D ANIMATED HUMAN BEHAVIORS FOR VIRTUAL WORLDS

    E-Print Network [OSTI]

    Plotkin, Joshua B.

    i CREATING 3D ANIMATED HUMAN BEHAVIORS FOR VIRTUAL WORLDS Jan M. Allbeck A DISSERTATION in Computer, and a scholar. #12;iv ABSTRACT CREATING 3D ANIMATED HUMAN BEHAVIORS FOR VIRTUAL WORLDS Jan M. Allbeck Norman I. Badler Creating virtual scenarios that simulate a substantial human population with typical and varied

  11. Towards an Intelligent Affective Multimodal Virtual Agent for Uncertain Environments

    E-Print Network [OSTI]

    Baldassarri, Sandra

    . It is based on the integration of Maxine, a powerful multimodal animation engine for managing virtual agents-time animation. 1. INTRODUCTION Most research on social interfaces is related to the design of virtual agents human- computer interface [1, 2]. A virtual agent must be believable: it has to move properly, paying

  12. Perception of Body and Hand Animations for Realistic Virtual Characters

    E-Print Network [OSTI]

    Duchowski, Andrew T.

    Perception of Body and Hand Animations for Realistic Virtual Characters Sophie J¨org Dissertation human is still a big challenge. The motions of a virtual character in a movie or in a game have a large. However, despite great improvements in recent years, creating a persua- sive and highly realistic virtual

  13. Virtual Humans for Animation, Ergonomics, and Simulation Norman Badler

    E-Print Network [OSTI]

    Badler, Norman I.

    Virtual Humans for Animation, Ergonomics, and Simulation Norman Badler Center for Human Modeling speed and control methods needed to portray 3D virtual humans suitable for real interactive applications of Pennsylvania with the Jack system. Various aspects of real­time virtual humans are considered

  14. The Virtual Stuntman: Dynamic Characters with a Repertoire of

    E-Print Network [OSTI]

    Terzopoulos, Demetri

    properly. Key words: Artificial Life, Virtual Humans, Computer Animation, Character Animation, Physics An ambitious goal in the area of physics-based computer animation is the creation of virtual actors virtual humans [1,5], physics-based an- imated characters with a large repertoire of motor skills have so

  15. An Interactive Interface for Directing Virtual Gael Sannier

    E-Print Network [OSTI]

    Pratt, Vaughan

    1015 Lausanne, Switzerland Abstract. Research on Virtual Humans spans from body animation to speech important issues: - Fully integrated virtual humans with facial and body animation, and speech. - A straightforward user interface for designers and directors. VHD system provides a range of virtual human animation

  16. The Director's Lens: An Intelligent Assistant for Virtual Cinematography

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    .1 [Multimedia Information Systems]: Animations, Video General Terms Algorithms, Human Factors Keywords Virtual-generated animations, the task of crafting virtual camera work and edits for a sequence of 3D animation remains a timeThe Director's Lens: An Intelligent Assistant for Virtual Cinematography Christophe Lino IRISA

  17. Jacob -An Animated Instruction Agent in Virtual Reality

    E-Print Network [OSTI]

    Nijholt, Anton

    of a 3D virtual environment where an animated human- like agent called Jacob gives instructionJacob - An Animated Instruction Agent in Virtual Reality Marc Evers1, Anton Nijholt1 1 University of virtual reality techniques and in- volves the design and construction of an animated agent in a 3

  18. Virtualizing Operating Systems for Seamless Distributed Environments

    E-Print Network [OSTI]

    Dasgupta, Partha

    Virtualizing Operating Systems for Seamless Distributed Environments 1 Tom Boyd and Partha Dasgupta of the "Computing Communities" project, a joint effort between Arizona State University and New York University. Abstract Applications and operating systems can be augmented with extra functionality by injecting

  19. Collaborative Virtual Environment Standards: A Performance Evaluation

    E-Print Network [OSTI]

    Ottawa, University of

    for each standard varies from graphics and rendering to simulation and network communication. Standards categories: Rendering and Graphics and Communications Middleware. 2.1 Rendering and Graphics These standards1 Collaborative Virtual Environment Standards: A Performance Evaluation Jauvane C. de Oliveira

  20. Collision Avoidance in Virtual Environments through

    E-Print Network [OSTI]

    Beckhaus, Steffi

    no counterpart in VEs. Examples are temperature difference (cold exterior walls radiating coolness we describe a new technique to make users aurally aware of walls surrounding them in a Virtual Interfaces: Auditory (non-speech) feedback. General Terms Design, Experimentation, Human Factors, Performance

  1. Colour dipoles and deeply virtual Compton scattering

    E-Print Network [OSTI]

    R. Sandapen

    2002-07-01T23:59:59.000Z

    I report on an analysis of Deeply Virtual Compton Scattering (DVCS) within the dipole model, done in collaboration with M. McDermott and G. Shaw. The two models considered here are distinct in their structure and implications. They both agree with the available cross-section data on DVCS from HERA. Predictions for various asymmetries are also given.

  2. Prudhoe Bay Oil Production Optimization: Using Virtual

    E-Print Network [OSTI]

    Mohaghegh, Shahab

    1 Prudhoe Bay Oil Production Optimization: Using Virtual Intelligence Techniques, Stage One: Neural total field oil production by optimizing the gas discharge rates and pressures at the separation handling capacity and subsequent oil production. 10 YEAR AVERAGE AMBIENT 1990-2000 & 2001, 2002 Averages

  3. A Virtual Infrastructure for Wireless Sensor Networks

    E-Print Network [OSTI]

    Stojmenovic, Ivan

    &CHAPTER 4 A Virtual Infrastructure for Wireless Sensor Networks STEPHAN OLARIU and QINGWEN XU Old, and wireless communications 107 Handbook of Sensor Networks: Algorithms and Architectures, Edited by I and communication infra- structures, called wireless sensor networks, will have a significant impact on a wide array

  4. DOE Sustainability Awards Best Practices Virtual Workshop

    Broader source: Energy.gov [DOE]

    The Sustainability Performance Office (SPO) will host a virtual best practices workshop on April 23, 2014 (2:00-3:30 PM EDT) to recognize the winners of the 2013 DOE Sustainability Awards. Award winners will present on their accomplishments and answer brief questions on their programs and projects. Please join us in celebrating the 2013 DOE Sustainability Awards winners.

  5. Ames Lab 101: C6: Virtual Engineering

    ScienceCinema (OSTI)

    None

    2012-08-29T23:59:59.000Z

    Ames Laboratory scientist Doug McCorkle explains the importance of virtual engineering and talks about the C6. The C6 is a three-dimensional, fully-immersive synthetic environment residing in the center atrium of Iowa State University's Howe Hall.

  6. A Reconfiguration Language for Virtualized Grid Infrastructures

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    ´eger, and Jean-Marc Menaud Ascola (EMN/INRIA, LINA) Ecole des Mines de Nantes 4, rue Alfred Kastler 44307 Nantes Systems (DAIS), France (2010)" #12;2 R´emy Pottier, Marc L´eger, and Jean-Marc Menaud virtual machine

  7. A Reconfiguration Language for Virtualized Grid Infrastructures

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    ´eger, and Jean-Marc Menaud Ascola (EMN/INRIA, LINA) Ecole des Mines de Nantes 4, rue Alfred Kastler 44307 Nantes : 10.1007/978-3-642-13645-0_4 #12;2 R´emy Pottier, Marc L´eger, and Jean-Marc Menaud virtual machine

  8. Talk to the Virtual Hands: Self-Animated Avatars Improve Communication in Head-Mounted Display Virtual

    E-Print Network [OSTI]

    Talk to the Virtual Hands: Self-Animated Avatars Improve Communication in Head-Mounted Display Virtual Environments Trevor J. Dodds1 *, Betty J. Mohler1 , Heinrich H. Bu¨ lthoff1,2 1 Human Perception¨lthoff HH (2011) Talk to the Virtual Hands: Self-Animated Avatars Improve Communication in Head

  9. February 13, 2008 Virtualized Environments for the Harness High Performance Computing Workbench 1/17 Virtualized Environments for the Harness

    E-Print Network [OSTI]

    Engelmann, Christian

    February 13, 2008 Virtualized Environments for the Harness High Performance Computing Workbench 1/17 Virtualized Environments for the Harness High Performance Computing Workbench Björn Könning1,2, Christian Virtualized Environments for the Harness High Performance Computing Workbench 4/17 Harness HPC Workbench

  10. 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.

    2015-03-24T23:59:59.000Z

    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.

  11. 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.

    2015-03-24T23:59:59.000Z

    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

  12. Variations on stability

    E-Print Network [OSTI]

    Ruben Minasian; Alessandro Tomasiello

    2002-05-07T23:59:59.000Z

    We explore the effects of non-abelian dynamics of D-branes on their stability and introduce Hitchin-like modifications to previously-known stability conditions. The relation to brane-antibrane systems is used in order to rewrite the equations in terms of superconnections and arrive at deformed vortex equations.

  13. Variations on stability

    E-Print Network [OSTI]

    Minasian, R; Minasian, Ruben; Tomasiello, Alessandro

    2001-01-01T23:59:59.000Z

    We explore the effects of non-abelian dynamics of D-branes on their stability and introduce Hitchin-like modifications to previously-known stability conditions. The relation to brane-antibrane systems is used in order to rewrite the equations in terms of superconnections and arrive at deformed vortex equations.

  14. Homological stabilizer codes

    SciTech Connect (OSTI)

    Anderson, Jonas T., E-mail: jonastyleranderson@gmail.com

    2013-03-15T23:59:59.000Z

    In this paper we define homological stabilizer codes on qubits which encompass codes such as Kitaev's toric code and the topological color codes. These codes are defined solely by the graphs they reside on. This feature allows us to use properties of topological graph theory to determine the graphs which are suitable as homological stabilizer codes. We then show that all toric codes are equivalent to homological stabilizer codes on 4-valent graphs. We show that the topological color codes and toric codes correspond to two distinct classes of graphs. We define the notion of label set equivalencies and show that under a small set of constraints the only homological stabilizer codes without local logical operators are equivalent to Kitaev's toric code or to the topological color codes. - Highlights: Black-Right-Pointing-Pointer We show that Kitaev's toric codes are equivalent to homological stabilizer codes on 4-valent graphs. Black-Right-Pointing-Pointer We show that toric codes and color codes correspond to homological stabilizer codes on distinct graphs. Black-Right-Pointing-Pointer We find and classify all 2D homological stabilizer codes. Black-Right-Pointing-Pointer We find optimal codes among the homological stabilizer codes.

  15. Stabilized radio frequency quadrupole

    DOE Patents [OSTI]

    Lancaster, Henry D. (Orinda, CA); Fugitt, Jock A. (Berkeley, CA); Howard, Donald R. (Danville, CA)

    1984-01-01T23:59:59.000Z

    A long-vane stabilized radio frequency resonator for accelerating charged particles and including means defining a radio frequency resonator cavity, a plurality of long vanes mounted in the defining means for dividing the cavity into sections, and means interconnecting opposing ones of the plurality of vanes for stabilizing the resonator.

  16. Phase-locked OH-PLIF of Oscillating Flame in Micro Channels FAN, Yong1*, SUZUKI, Yuji1, KASAGI, Nobuhide1

    E-Print Network [OSTI]

    Kasagi, Nobuhide

    excitation lines [6]. Experimental setup of phase-locked OH-PLIF imaging has been developedPhase-locked OH-PLIF of Oscillating Flame in Micro Channels FAN, Yong1*, SUZUKI, Yuji1, KASAGI in the oscillation process are investigated with phase-locked OH-PLIF imaging technique. 2. Flame velocity Figures. 1

  17. Plasmas and Polymers, Vol. 8, No. 1, March 2003 ( C 2003) A Comparison of Corona-Treated and Flame-Treated

    E-Print Network [OSTI]

    Kushner, Mark

    Plasmas and Polymers, Vol. 8, No. 1, March 2003 ( C 2003) A Comparison of Corona-Treated and Flame-Treated of corona-treated and flame-treated polypropylene (PP) films provides insight into the mechanism-ray photoelectron spectroscopy (XPS or ESCA) were used to characterize surface-treated biaxially oriented PP. While

  18. Enhancements of a Combustion Vessel to Determine Laminar Flame Speeds of Hydrocarbon Blends with Helium Dilution at Elevated Temperatures and Pressures

    E-Print Network [OSTI]

    Plichta, Drew

    2013-04-03T23:59:59.000Z

    of importance comes the need for baseline data such as laminar flame speed of said fuels. While flame speeds at standard temperature and pressure have been extensively studied in the literature, experimental data at turbine-like conditions are still lacking...

  19. Global modes, receptivity, and sensitivity analysis of diffusion flames coupled with duct

    E-Print Network [OSTI]

    Magri, Luca; Juniper, Matthew P.

    2015-01-01T23:59:59.000Z

    to the performance of the system. 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... ,B,C,D and in the online supplementary material. 2. Thermo-acoustic model The thermo-acoustic model consists of a diffusion flame placed in an acoustic duct (figure 1). The acoustic waves cause perturbations in the velocity field. In turn, these Receptivity and sensitivity...

  20. 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. [Sandia National Labs., Livermore, CA (United States). Thermal and Plasma Processes Dept.

    1997-05-01T23:59:59.000Z

    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.

  1. Horsehead Resource Development Company, Inc. , flame reactor technology. Technology demonstration summary

    SciTech Connect (OSTI)

    Not Available

    1992-10-01T23:59:59.000Z

    Under the Superfund Innovative Technology Evaluation (SITE) program, the Horsehead Resource Development Company, Inc., (HRD) Flame Reactor was evaluated during a series of test runs. The tests were conducted at the HRD facility in Monaca, PA, using 72 tons of secondary lead smelter soda slag (waste feed) from the National Smelting and Refining Company, Inc., site in Atlanta, GA. The waste feed contained lead, zinc, iron, and many other metals and inorganic compounds. This summary includes an overview of the demonstration, a technology description, analytical results, and conclusions.

  2. 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)

    2011-03-15T23:59:59.000Z

    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.

  3. 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

    2013-05-07T23:59:59.000Z

    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.

  4. Sub-millikelvin stabilization of a closed cycle cryocooler

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

    Dubuis, Guy [Brookhaven National Lab. (BNL), Upton, NY (United States); He, Xi [Brookhaven National Lab. (BNL), Upton, NY (United States); Bozovic, Ivan [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2014-10-01T23:59:59.000Z

    Intrinsic temperature oscillations (with the amplitude up to 1 K) of a closed cycle cryocooler are stabilized by a simple thermal damping system. It employs three different materials with different thermal conductivity and capacity at various temperatures. The amplitude of oscillations of the sample temperature is reduced to less than 1 mK, in the temperature range from 4 K to 300 K, while the cooling power is virtually undiminished. The damping system is small, inexpensive, can be retrofitted to most existing closed cycle cryocoolers, and may improve measurements of any temperature-sensitive physics properties.

  5. Two-dimensional imaging of gas-to-particle transition in flames by laser-induced nanoplasmas

    SciTech Connect (OSTI)

    Zhang, Yiyang [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Li, Shuiqing, E-mail: lishuiqing@tsinghua.edu.cn; Ren, Yihua; Yao, Qiang [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China); Law, Chung K. [Center for Combustion Energy, Tsinghua University, Beijing 100084 (China); Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544-5263 (United States)

    2014-01-13T23:59:59.000Z

    Two-dimensional imaging of gas/particle phase transition of metal oxides in their native high-temperature flow conditions, using laser-driven localized nanoplasmas, was obtained by utilizing the gap between the excitation energies of the gas and particle phases such that only the Ti atoms in the particle phase were selectively excited without detectable Bremsstrahlung background. These in situ images of the particle phase Ti distribution allow the quantitative visualization of the transition of the gas precursors to the nanoparticle phase across the flame sheet as well as diffusion of the particle concentration in the post-flame zone.

  6. A STUDY ON SPHERICAL EXPANDING FLAME SPEEDS OF METHANE, ETHANE, AND METHANE/ETHANE MIXTURES AT ELEVATED PRESSURES 

    E-Print Network [OSTI]

    De Vries, Jaap

    2010-07-14T23:59:59.000Z

    .......................................................................... 25? Figure 19. Number of GE gas turbines by fuel type, (source Campbell et al. [4]). ............ 28? Figure 20. Flame sheet dividing unburned reactants from the burned products. ............... 36? Figure 21. Mole fraction of CH 4 , O 2 , H... Situation in the US This study focuses on flame speeds of Natural-Gas (NG) fuel blends used by power- generation gas turbines. Demand for high-pressure combustion data of current and future candidate fuels is directly connected to changes in the world?s...

  7. Heavy quarks in deeply virtual Compton scattering

    E-Print Network [OSTI]

    Jens D. Noritzsch

    2003-12-11T23:59:59.000Z

    A detailed study of the heavy quark h=c,b,... contributions to deeply virtual Compton scattering is performed at both the amplitude and the cross section level, and their phenomenological relevance is discussed. For this purpose I calculate the lowest order off-forward photon-gluon scattering amplitude with a massive quark loop and the corresponding hard scattering coefficients. In a first numerical analysis these fixed order perturbation theory results are compared with the conventional intrinsic "massless" parton approach considering generalized parton distributions for the heavy quarks. The differences between these two prescriptions can be quite significant, especially at small skewedness where the massless approach largely overestimates the deeply virtual Compton scattering cross section.

  8. Controlled entanglement routing between two virtual pathways

    E-Print Network [OSTI]

    Qiang Zhou; Shuai Dong; Wei Zhang; Lixing You; Yuhao He; Weijun Zhang; Yidong Huang; Jiangde Peng

    2014-07-16T23:59:59.000Z

    We demonstrate controlled entanglement routing between bunching and antibunching path-entangled two-photon states in an unbalanced Mach-Zehnder interferometer (UMZI), in which the routing process is controlled by the relative phase difference in the UMZI. Regarding bunching and antibunching path-entangled two-photon states as two virtual ports, we can consider the UMZI as a controlled entanglement router, which bases on the coherent manipulation of entanglement. Half of the entanglement within the input two-photon state is coherently routed between the two virtual ports, while the other is lost due to the time distinguishability introduced by the UMZI. Pure bunching or antibunching path entangled two-photon states are obtained based on this controlled entanglement router. The results show that we can employ the UMZI as general entanglement router for practical quantum information application.

  9. 3D Spectroscopy and the Virtual Observatory

    E-Print Network [OSTI]

    Bryan W. Miller

    2007-08-15T23:59:59.000Z

    Integral field, or 3D, spectroscopy is the technique of obtaining spectral information over a two-dimensional, hopefully contiguous, field of view. While there is some form of astronomical 3D spectroscopy at all wavelengths, there has been a rapid increase in interest in optical and near-infrared 3D spectroscopy. This has resulted in the deployment of a large variety of integral-field spectrographs on most of the large optical/infrared telescopes. The amount of IFU data available in observatory archives is large and growing rapidly. The complications of treating IFU data as both imaging and spectroscopy make it a special challenge for the virtual observatory. This article describes the various techniques of optical and near-infrared spectroscopy and some of the general needs and issues related to the handling of 3D data by the virtual observatory.

  10. Spin effects in deeply virtual Compton scattering

    E-Print Network [OSTI]

    A. V. Belitsky; A. Kirchner; D. Müller

    2001-06-21T23:59:59.000Z

    We consider the azimuthal angle dependence in the cross section of the hard leptoproduction of a photon on a nucleon target. We show that this dependence allows to define observables that isolate the twist-two and twist-three sectors in the deeply virtual Compton scattering amplitude. All twist-two and twist-three Compton form factors can be extracted from measurements of the charge odd part of the polarized cross section and give access to all generalized parton distributions.

  11. Knowledge Discovery Framework for the Virtual Observatory

    E-Print Network [OSTI]

    Thomas, Brian; Huang, Zenping; Teuben, Peter

    2015-01-01T23:59:59.000Z

    We describe a framework that allows a scientist-user to easily query for information across all Virtual Observatory (VO) repositories and pull it back for analysis. This framework hides the gory details of meta-data remediation and data formatting from the user, allowing them to get on with search, retrieval and analysis of VO data as if they were drawn from a single source using a science based terminology rather than a data-centric one.

  12. Deeply virtual Compton scattering off nuclei

    SciTech Connect (OSTI)

    Voutier, Eric

    2009-01-01T23:59:59.000Z

    Deeply virtual Compton scattering (DVCS) is the golden exclusive channel for the study of the partonic structure of hadrons, within the universal framework of generalized parton distributions (GPDs). This paper presents the aim and general ideas of the DVCS experimental program off nuclei at the Jefferson Laboratory. The benefits of the study of the coherent and incoherent channels to the understanding of the EMC (European Muon Collaboration) effect are discussed, along with the case of nuclear targets to access neutron GPDs.

  13. Thermal Stabilization Blend Plan

    SciTech Connect (OSTI)

    RISENMAY, H.R.

    2000-05-02T23:59:59.000Z

    This Blend Plan documents the feed material items that are stored in 2736-2 vaults, the 2736-ZB 638 cage, the 192C vault, and the 225 vault that will be processed through the thermal stabilization furnaces. The purpose of thermal stabilization is to heat the material to 1000 degrees Celsius to drive off all water and leave the plutonium and/or uranium as oxides. The stabilized material will be sampled to determine the Loss On Ignition (LOI) or percent water. The stabilized material must meet water content or LOI of less than 0.5% to be acceptable for storage under DOE-STD-3013-99 specifications. Out of specification material will be recycled through the furnaces until the water or LOI limits are met.

  14. Computational Fluid Dynamics Modeling of the Operation of a Flame Ionization Sensor

    SciTech Connect (OSTI)

    Huckaby, E.D.; Chorpening, B.T.; Thornton, J.D.

    2007-03-01T23:59:59.000Z

    The sensors and controls research group at the United States Department of Energy (DOE) National Energy Technology Laboratory (NETL) is continuing to develop the Combustion Control and Diagnostics Sensor (CCADS) for gas turbine applications. CCADS uses the electrical conduction of the charged species generated during the combustion process to detect combustion instabilities and monitor equivalence ratio. As part of this effort, combustion models are being developed which include the interaction between the electric field and the transport of charged species. The primary combustion process is computed using a flame wrinkling model (Weller et. al. 1998) which is a component of the OpenFOAM toolkit (Jasak et. al. 2004). A sub-model for the transport of charged species is attached to this model. The formulation of the charged-species model similar that applied by Penderson and Brown (1993) for the simulation of laminar flames. The sub-model consists of an additional flux due to the electric field (drift flux) added to the equations for the charged species concentrations and the solution the electric potential from the resolved charge density. The subgrid interactions between the electric field and charged species transport have been neglected. Using the above procedure, numerical simulations are performed and the results compared with several recent CCADS experiments.

  15. 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)

    2005-12-01T23:59:59.000Z

    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.

  16. Transported PDF Modeling of Nonpremixed Turbulent CO/H-2/N-2 Jet Flames

    SciTech Connect (OSTI)

    Zhao, xinyu; Haworth, D. C.; Huckaby, E. David

    2012-01-01T23:59:59.000Z

    Turbulent CO/H{sub 2}/N{sub 2} (“syngas”) flames are simulated using a transported composition probability density function (PDF) method. A consistent hybrid Lagrangian particle/Eulerian mesh algorithm is used to solve the modeled PDF transport equation. The model includes standard k–? turbulence, gradient transport for scalars, and Euclidean minimum spanning tree (EMST) mixing. Sensitivities of model results to variations in the turbulence model, the treatment of radiation heat transfer, the choice of chemical mechanism, and the PDF mixing model are explored. A baseline model reproduces the measured mean and rms temperature, major species, and minor species profiles reasonably well, and captures the scaling that is observed in the experiments. Both our results and the literature suggest that further improvements can be realized with adjustments in the turbulence model, the radiation heat transfer model, and the chemical mechanism. Although radiation effects are relatively small in these flames, consideration of radiation is important for accurate NO prediction. Chemical mechanisms that have been developed specifically for fuels with high concentrations of CO and H{sub 2} perform better than a methane mechanism that was not designed for this purpose. It is important to account explicitly for turbulence–chemistry interactions, although the details of the mixing model do not make a large difference in the results, within reasonable limits.

  17. Thermonuclear Flame Spreading on Rapidly Spinning Neutron Stars: Indications of the Coriolis Force?

    E-Print Network [OSTI]

    Sudip Bhattacharyya; Tod E. Strohmayer

    2007-08-27T23:59:59.000Z

    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.

  18. Proceedings of the international workshop on measurement and computation of turbulent nonpremixed flames

    SciTech Connect (OSTI)

    Barlow, R.S. [ed.

    1996-10-01T23:59:59.000Z

    This report documents the proceedings of the International Workshop on Measurement and Computation of Turbulent Nonpremixed Flames, held in Naples, Italy on July 26--27, 1996. Contents include materials that were distributed to participants at the beginning of the workshop, as well as a Summary of Workshop Accomplishments that was generated at the close to this Naples meeting. The Naples workshop involved sixty-one people from eleven countries. The primary objectives were: (1) to select a set of well-documented and relatively simple flames that would be appropriate for collaborative comparisons of model predictions; and (2) to specify common submodels to be used in these predictions, such that models for the coupling of turbulence and chemistry might be isolated and better understood. Studies involve hydrogen and natural gas fuels. These proceedings are also published on the Web and those interested in the ongoing process of data selection and model comparison should consult the workshop page for the most recent and complete information on these collaborative research efforts. The URL is: http://www/ca.sandia/gov/tdf/Workshop.html.

  19. Virtual and super - virtual refraction method: Application to synthetic data and 2012 of Karangsambung survey data

    SciTech Connect (OSTI)

    Nugraha, Andri Dian [Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Institute of Technology Bandung, Bandung, 40132 (Indonesia)] [Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Institute of Technology Bandung, Bandung, 40132 (Indonesia); Adisatrio, Philipus Ronnie [Geophysical Engineering Department, Faculty of Mining and Petroleum Engineering, Institute of Technology Bandung, Jl. Ganesha No. 10 Bandung, 40132 (Indonesia)] [Geophysical Engineering Department, Faculty of Mining and Petroleum Engineering, Institute of Technology Bandung, Jl. Ganesha No. 10 Bandung, 40132 (Indonesia)

    2013-09-09T23:59:59.000Z

    Seismic refraction survey is one of geophysical method useful for imaging earth interior, definitely for imaging near surface. One of the common problems in seismic refraction survey is weak amplitude due to attenuations at far offset. This phenomenon will make it difficult to pick first refraction arrival, hence make it challenging to produce the near surface image. Seismic interferometry is a new technique to manipulate seismic trace for obtaining Green's function from a pair of receiver. One of its uses is for improving first refraction arrival quality at far offset. This research shows that we could estimate physical properties such as seismic velocity and thickness from virtual refraction processing. Also, virtual refraction could enhance the far offset signal amplitude since there is stacking procedure involved in it. Our results show super - virtual refraction processing produces seismic image which has higher signal-to-noise ratio than its raw seismic image. In the end, the numbers of reliable first arrival picks are also increased.

  20. 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)

    2006-12-15T23:59:59.000Z

    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)

  1. Towards Real Time Virtual Human Life Simulations Etienne de Sevin, Marcelo Kallmann and Daniel Thalmann

    E-Print Network [OSTI]

    Kallmann, Marcelo

    Life, Agents, Virtual Humans, Virtual Environments, Behavioral Animation, Classifier Systems, ObjectTowards Real Time Virtual Human Life Simulations Etienne de Sevin, Marcelo Kallmann and Daniel for the development of artificial virtual human life simulations. Our main goal is to have virtual human actors living

  2. Virtual Workshops: Using Today's Networking Tools to Train Tomorrow's Experts

    E-Print Network [OSTI]

    Kane, J. F.; Bailey, W. F.

    VIRTUAL WORKSHOPS: USING TODAY'S NETWORKING TOOLS TO TRAIN TOMORROW'S EXPERTS John F. Kane, Jr., PE, CEM Senior Consulting Engineer E. 1. du Pont de Nemours and Company, Inc. Charlotte, North Carolina ABSTRACT Training and development... ing," while others call it "virtual presentations." Regardless, a virtual workshop - as we have defmed the term - is a new way to transfer rich and useful information from a subject matter expert to a very large group of people who have a genuine...

  3. 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

    1995-01-01T23:59:59.000Z

    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...

  4. Fractal Analysis of Flame-Synthesized Nanostructured Silica and Titania Powders Using Small-Angle X-ray

    E-Print Network [OSTI]

    Beaucage, Gregory

    Fractal Analysis of Flame-Synthesized Nanostructured Silica and Titania Powders Using Small-Angle X these powders display mass-fractal morphologies, which are composed of ramified aggregates of nanoscale primary particles. Primary particle size, aggregate size, fractal dimension, and specific surface area are obtained

  5. 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.

    2011-01-01T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Apte, Sourabh V.

    903 Proceedings of the Combustion Institute, Volume 28, 2000/pp. 903­910 TURBULENT FLAME DYNAMICS University Park, PA 16802, USA A comprehensive numerical analysis has been conducted to study the combustion development and its influence on propellant combustion. The formulation is based on the Favre

  7. Simultaneous measurements of soot volume fraction and particle size/microstructure in flames using a thermophoretic sampling technique

    SciTech Connect (OSTI)

    Koeylue, U.O.; McEnally, C.S.; Rosner, D.E.; Pfefferle, L.D. [Yale Univ., New Haven, CT (United States). Dept. of Chemical Engineering] [Yale Univ., New Haven, CT (United States). Dept. of Chemical Engineering

    1997-09-01T23:59:59.000Z

    A new particle volume fraction measurement technique was developed using electron microscope analysis of thermophoretically sampled particles/aggregates based on a theoretical treatment of particle deposition to a cold surface immersed in a flame. This experimental method, referred to as the thermophoretic sampling particle diagnostic (TSPD), can yield all particle parameters of principal interest (particle volume fraction, particle and aggregate sizes, and fractal properties) without requiring knowledge of particle bulk density and refractive index. To assess its reliability, the TSPD technique was implemented at various heights on the centerline of a soot-containing coflowing ethylene/air nonpremixed laminar flame. Inferred soot volume fractions agreed with previous laser extinction and thermocouple particle densitometry measurements within experimental uncertainties at sampling positions where only aggregates of mature particles were present. However, TSPD-soot volume fractions were about a factor of 3 higher than light extinction results in the lower part of the flame. This significant difference was evidently a result of the presence of translucent precursor soot particles, which do not absorb as much visible light as mature particles, but can be quantified with the electron microscope. Clearly, this ability of TSPD to separately measure the concentration and morphology of each type of soot is a significant advantage over other available diagnostics, making it extremely valuable for studying particle formation in flames.

  8. 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

    1995-01-01T23:59:59.000Z

    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...

  9. Assessment of kinetic modeling for lean H2/CH4/O2/diluent flames at high pressures

    E-Print Network [OSTI]

    Ju, Yiguang

    : Hydrogen; Methane; Syngas; Flame speed; Chemical mechanism 1. Introduction The H2/O2 reaction system CO, CO2, H2O, CH4 and other small hydrocarbons (synthetic gas or "syngas") from coal or biomass gasification [2]. Typical syngas mixtures can contain significant amounts of small molecular weight

  10. applied virtual reality: Topics by E-print Network

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

    of immersive applications, which provides a virtual reality system-independent operating environment. The thesis focuses on the approach taken to specify, design, and...

  11. applying virtual reality: Topics by E-print Network

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

    of immersive applications, which provides a virtual reality system-independent operating environment. The thesis focuses on the approach taken to specify, design, and...

  12. Employing Virtualization in Library Computing: Use Cases and Lessons Learned

    E-Print Network [OSTI]

    Hutt, Arwen E.; Stuart, Michael; Suchy, Daniel; Westbrook, Bradley D.

    2009-01-01T23:59:59.000Z

    cataloging. Not only are types of library materials changingincreasing variety of library material types. Most notableLibraries. 2 Virtualization can be implemented using Type 1

  13. Deeply virtual Compton scattering and generalized parton distributions

    E-Print Network [OSTI]

    S. Fazio; R. Fiore; L. L. Jenkovszky

    2008-12-16T23:59:59.000Z

    We present a comparison of a recently proposed model, which describes the Deeply Virtual Compton Scattering amplitude, to the HERA data.

  14. The Virtual (Re)Construction of History: Some Epistemological Questions

    E-Print Network [OSTI]

    El Antably, Ahmed

    2010-01-01T23:59:59.000Z

    virtual environments as a new medium for representingvirtual environments as a new medium for representingmedium that are specific to the society in which the environment

  15. Teaching Variation Reduction Using a Virtual Manufacturing Environment

    E-Print Network [OSTI]

    Zhu, Mu

    short courses. KEY WORDS: Simulation; Six Sigma; Variation reduction; Virtual environment. 1 by adopting a systematic frame- work like DMAIC (define, measure, analyze, improve, control) in Six Sigma

  16. Proposed Virtual Center for Excellence for Metal Hydride Development...

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

    Virtual Center for Excellence for Metal Hydride Development Presentation from the Hydrogen Storage Pre-Solicitation Meeting held June 19, 2003 in Washington, DC....

  17. Virtual Center of Excellence for Hydrogen Storage - Chemical...

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

    funded) * Advanced carbon materials (LDRD) - (we propose a support role in the carbon materials virtual center) * Electrochemically active barrier liner for composite storage tanks...

  18. T-588: HP Virtual SAN Appliance Stack Overflow

    Broader source: Energy.gov [DOE]

    A vulnerability has been reported in HP StorageWorks P4000 Virtual SAN Appliance Software, which can be exploited by malicious people to compromise a vulnerable system.

  19. I/O Performance of Virtualized Cloud Environments

    E-Print Network [OSTI]

    Ghoshal, Devarshi

    2013-01-01T23:59:59.000Z

    Technologies in High Performance Computing. In 2nd IEEEusing virtual high-performance computing: a case study usingAnalysis of High Performance Computing Applications on the

  20. A Stochastic Reactor Based Virtual Engine Model Employing Detailed...

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

    A Stochastic Reactor Based Virtual Engine Model Employing Detailed Chemistry for Kinetic Studies of In-Cylinder Combustion and Exhaust Aftertreatment A Stochastic Reactor Based...

  1. Effect of syngas composition and CO2-diluted oxygen on performance of a premixed swirl-stabilized combustor.

    SciTech Connect (OSTI)

    Williams, Timothy C.; Shaddix, Christopher R.; Schefer, Robert W.

    2007-01-01T23:59:59.000Z

    Future energy systems based on gasification of coal or biomass for co-production of electrical power and fuels may require gas turbine operation on unusual gaseous fuel mixtures. In addition, global climate change concerns may dictate the generation of a CO{sub 2} product stream for end-use or sequestration, with potential impacts on the oxidizer used in the gas turbine. In this study the operation at atmospheric pressure of a small, optically accessible swirl-stabilized premixed combustor, burning fuels ranging from pure methane to conventional and H{sub 2}-rich and H{sub 2}-lean syngas mixtures is investigated. Both air and CO{sub 2}-diluted oxygen are used as oxidizers. CO and NO{sub x} emissions for these flames have been determined from the lean blowout limit to slightly rich conditions ({phi} - 1.03). In practice, CO{sub 2}-diluted oxygen systems will likely be operated close to stoichiometric conditions to minimize oxygen consumption while achieving acceptable NO{sub x} performance. The presence of hydrogen in the syngas fuel mixtures results in more compact, higher temperature flames, resulting in increased flame stability and higher NO{sub x} emissions. Consistent with previous experience, the stoichiometry of lean blowout decreases with increasing H{sub 2} content in the syngas. Similarly, the lean stoichiometry at which CO emissions become significant decreases with increasing H{sub 2} content. For the mixtures investigated, CO emissions near the stoichiometric point do not become significant until {phi} > 0.95. At this stoichiometric limit, CO emissions rise more rapidly for combustion in O{sub 2}-CO{sub 2} mixtures than for combustion in air.

  2. NO{sub x} emissions of a jet diffusion flame which is surrounded by a shroud of combustion air

    SciTech Connect (OSTI)

    Tran, P.X.; White, F.P.; Mathur, M.P.; Ekmann, J.M.

    1996-08-01T23:59:59.000Z

    The present work reports an experimental study on the behavior of a jet flame surrounded by a shroud of combustion air. Measurements focussed on the flame length and the emissions of NO{sub x}, total unburned hydrocarbons, CO{sub 2}, and O{sub 2}. Four different fuel flow rates (40.0, 78.33, 138.33, and 166.6 cm/s), air flow rates up to 2500 cm{sup 3}/s and four different air injector diameters (0.079 cm, 0. 158 cm, 0.237 cm, and 0.316 cm) were used. The shroud of combustion air causes the flame length to decrease by a factor proportional to 1/[p{sub a}/p{sub f} + C{sub 2}({mu}{sub a}Re,a/{mu}{sub f}Re,f){sup 2}]{sup {1/2}}. A substantial shortening of the flame length occurred by increasing the air injection velocity keeping fuel rate fixed or conversely by lowering the fuel flow rate keeping air flow rate constant. NO{sub x} emissions ranging from 5 ppm to 64 ppm were observed and the emission of NO{sub x} decreased strongly with the increased air velocity. The decrease of NO{sub x} emissions was found to follow a similar scaling law as does the flame length. However, the emission of the total hydrocarbons increased with the increased air velocity or the decreased fuel flow rate. A crossover condition where both NO{sub x} and unburned- hydrocarbon emissions are low, was identified. At an air-to-fuel velocity ratio of about 1, the emissions of NO{sub x} and the total hydrocarbons were found to be under 20 ppm.

  3. Energy efficient mapping of virtualEnergy efficient mapping of virtual machinesmachines

    E-Print Network [OSTI]

    Lefèvre, Laurent

    for energy savings in cloud 2 Violaine Villebonnet GreenDays@Lille 28th November 2013 Problematic algorithms that best fit with reality Energy efficient mapping of virtual machines Violaine Villebonnet Green Conditioning Reduce the energy consumption of the whole datacenter Violaine Villebonnet GreenDays@Lille 28th

  4. Virtual interactive simulation and inspection tool (VISIT) Modeling sensor networks in a virtual city

    SciTech Connect (OSTI)

    Moore, D. M. (David M.)

    2004-01-01T23:59:59.000Z

    The U.S. government is currently investigating the deployment of radiation sensor systems to protect cities against nuclear and radiological threats. Due to the high cost of installing such systems, there is a need to analyze the effectiveness of a variety of sensor configurations in detecting such threats before installing such systems in the field. The Virtual Interactive Simulation and Inspection Tool (VISIT) is a computer program developed for various virtual-reality applications in national security programs, and is presently being adapted to test the efficacy of a variety of sensor configurations in a virtual urban environment. The value of a particular sensor configuration will be assessed by running virtual exercises in which a threat team will choose a radiological device and route to a target and a detection team will specify the locations and types of sensors to be placed in the city to attempt detection of the threat prior to it reaching its target. This paper will discuss the VISIT package, its proposed application, and lessons learned from modeling done to date.

  5. Validating agent based models through virtual worlds.

    SciTech Connect (OSTI)

    Lakkaraju, Kiran; Whetzel, Jonathan H.; Lee, Jina [Sandia National Laboratories, Livermore, CA; Bier, Asmeret Brooke; Cardona-Rivera, Rogelio E. [North Carolina State University, Raleigh, NC; Bernstein, Jeremy Ray Rhythm [Gaikai, Inc., Aliso Viejo, CA

    2014-01-01T23:59:59.000Z

    As the US continues its vigilance against distributed, embedded threats, understanding the political and social structure of these groups becomes paramount for predicting and dis- rupting their attacks. Agent-based models (ABMs) serve as a powerful tool to study these groups. While the popularity of social network tools (e.g., Facebook, Twitter) has provided extensive communication data, there is a lack of ne-grained behavioral data with which to inform and validate existing ABMs. Virtual worlds, in particular massively multiplayer online games (MMOG), where large numbers of people interact within a complex environ- ment for long periods of time provide an alternative source of data. These environments provide a rich social environment where players engage in a variety of activities observed between real-world groups: collaborating and/or competing with other groups, conducting battles for scarce resources, and trading in a market economy. Strategies employed by player groups surprisingly re ect those seen in present-day con icts, where players use diplomacy or espionage as their means for accomplishing their goals. In this project, we propose to address the need for ne-grained behavioral data by acquiring and analyzing game data a commercial MMOG, referred to within this report as Game X. The goals of this research were: (1) devising toolsets for analyzing virtual world data to better inform the rules that govern a social ABM and (2) exploring how virtual worlds could serve as a source of data to validate ABMs established for analogous real-world phenomena. During this research, we studied certain patterns of group behavior to compliment social modeling e orts where a signi cant lack of detailed examples of observed phenomena exists. This report outlines our work examining group behaviors that underly what we have termed the Expression-To-Action (E2A) problem: determining the changes in social contact that lead individuals/groups to engage in a particular behavior. Results from our work indicate that virtual worlds have the potential for serving as a proxy in allocating and populating behaviors that would be used within further agent-based modeling studies.

  6. Deeply Virtual Compton Scattering off the neutron

    E-Print Network [OSTI]

    M. Mazouz; A. Camsonne; C. Muñoz Camacho; for the Jefferson Lab Hall A collaboration

    2007-12-12T23:59:59.000Z

    The present experiment exploits the interference between the Deeply Virtual Compton Scattering (DVCS) and the Bethe-Heitler processes to extract the imaginary part of DVCS amplitudes on the neutron and on the deuteron from the helicity-dependent D$({\\vec e},e'\\gamma)X$ cross section measured at $Q^2$=1.9 GeV$^2$ and $x_B$=0.36. We extract a linear combination of generalized parton distributions (GPDs) particularly sensitive to $E_q$, the least constrained GPD. A model dependent constraint on the contribution of the up and down quarks to the nucleon spin is deduced.

  7. Diffraction Patterns in Deeply Virtual Compton Scattering

    E-Print Network [OSTI]

    Asmita Mukherjee

    2006-11-30T23:59:59.000Z

    We report on a calculation to show that the Fourier transform of the Deeply Virtual Compton Scattering (DVCS) amplitude with respect to the skewness variable \\zeta at fixed invariant momentum transfer squared t gives results that are analogous to the diffractive scattering of a wave in optics. As a specific example, we utilize the quantum fluctuations of a fermion state at one loop in QED to obtain the behavior of the DVCS amplitude for electron-photon scattering. We then simulate the wavefunctions for a hadron by differentiating the above LFWFs with respect to M^2 and study the corresponding DVCS amplitudes in light-front longitudinal space.

  8. Deeply Virtual Compton Scattering at HERA II

    E-Print Network [OSTI]

    Laurent Schoeffel

    2007-05-22T23:59:59.000Z

    A new measurement is presented of elastic deeply virtual Compton scattering (DVCS) based on data taken by the H1 detector during the complete HERA II period. The data are well described by QCD based calculations. For the first time, a beam charge asymmetry is obtained in a colliding mode, using data recorded in $e^-p$ and $e^+p$. A significant non zero value is measured, related to the interference of QCD and QED processes, namely the DVCS and Bethe-Heitler reactions.

  9. Virtual Compton Scattering off the nucleon

    E-Print Network [OSTI]

    P. A. M. Guichon; M. Vanderhaeghen

    1998-06-08T23:59:59.000Z

    We review the recent developments of virtual Compton scattering. We focus on the kinematical regimes which look the most promising. The threshold regime gives access to the generalized polarizabilities of the proton. The hard scattering regime allows tests of perturbative QCD predictions and of the valence quark wave function. The Bjorken regime is closely related to deep inelastic scattering. It gives access to the off-forward parton distributions which generalize the ordinary parton distributions and may shed a new light on the spin problem. For each regime we discuss the experimental perspectives and the role of the Bethe-Heitler background.

  10. The Virtual Observatory and Grid in Spain

    E-Print Network [OSTI]

    J. D. Santander-Vela

    2008-07-08T23:59:59.000Z

    The Virtual Observatory (VO) is nearing maturity, and in Spain the Spanish VO (SVO) exists since June 2004. There have also been numerous attempts at providing more or less encompassing grid initiatives at the national level, and finally Spain has an official National Grid Initiative (NGI). In this article we will show the VO and Grid development status of nationally funded initiatives in Spain, and we will hint at potential joint VO-Grid use-cases to be developed in Spain in the near future.

  11. Virtual environments for nuclear power plant design

    SciTech Connect (OSTI)

    Brown-VanHoozer, S.A.; Singleterry, R.C. Jr.; King, R.W. [and others

    1996-03-01T23:59:59.000Z

    In the design and operation of nuclear power plants, the visualization process inherent in virtual environments (VE) allows for abstract design concepts to be made concrete and simulated without using a physical mock-up. This helps reduce the time and effort required to design and understand the system, thus providing the design team with a less complicated arrangement. Also, the outcome of human interactions with the components and system can be minimized through various testing of scenarios in real-time without the threat of injury to the user or damage to the equipment. If implemented, this will lead to a minimal total design and construction effort for nuclear power plants (NPP).

  12. Spring 2015 Virtual Toolkit | Department of Energy

    Office of Environmental Management (EM)

    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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742 33Frequently AskedEnergyIssues DOE's Nuclear EnergySmartOverviewEnergySpotlightingVirtual

  13. Stabilized PV system

    DOE Patents [OSTI]

    Dinwoodie, Thomas L. (Piedmont, CA)

    2002-12-17T23:59:59.000Z

    A stabilized PV system comprises an array of photovoltaic (PV) assemblies mounted to a support surface. Each PV assembly comprises a PV module and a support assembly securing the PV module to a position overlying the support surface. The array of modules is circumscribed by a continuous, belt-like perimeter assembly. Cross strapping, extending above, below or through the array, or some combination of above, below and through the array, secures a first position along the perimeter assembly to at least a second position along the perimeter assembly thereby stabilizing the array against wind uplift forces. The first and second positions may be on opposite sides on the array.

  14. Non-normality in combustion-acoustic interaction in diffusion flames: a critical revision

    E-Print Network [OSTI]

    Magri, Luca; Sujith, R I; Juniper, Matthew P

    2013-01-01T23:59:59.000Z

    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.

  15. On virtual phonons, photons and electrons

    E-Print Network [OSTI]

    G. Nimtz

    2009-07-09T23:59:59.000Z

    A macroscopic realization of the strange virtual particles is presented. The classical Helmholtz and the quantum mechanical Schr\\"odinger equations are analogous differential equations. Their imaginary solutions are called evanescent modes in the case of elastic and electromagnetic fields. In the case of non-relativistic quantum mechanical fields they are called tunneling solutions. The imaginary solutions of this differential equation point to strange consequences: They are non local, they are not observable, and they described as virtual particles. During the last two decades QED calculations of the imaginary solutions have been experimentally confirmed for phonons, photons, and for electrons. The experimental proofs of the predictions of the non-relativistic quantum mechanics and of the Wigner phase time approach for the elastic, the electromagnetic and the Schr\\"odinger fields will be presented in this article. The results are zero tunneling time and an interaction time (i.e. a phase shift) at the barrier interfaces. The measured barrier interaction time (i.e. the barrier transmission time) scales approximately inversely with the particle energy.

  16. Distribution of copper, silver and gold during thermal treatment with brominated flame retardants

    SciTech Connect (OSTI)

    Oleszek, Sylwia, E-mail: sylwia_oleszek@yahoo.com [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 1,1 Katahira, 2-Chome, Sendai 980-8577 (Japan); Institute of Environmental Engineering of the Polish Academy of Sciences, 34 M. Sklodowska-Curie St., 41-819 Zabrze (Poland); Grabda, Mariusz, E-mail: mariusz@mail.tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 1,1 Katahira, 2-Chome, Sendai 980-8577 (Japan); Institute of Environmental Engineering of the Polish Academy of Sciences, 34 M. Sklodowska-Curie St., 41-819 Zabrze (Poland); Shibata, Etsuro, E-mail: etsuro@tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 1,1 Katahira, 2-Chome, Sendai 980-8577 (Japan); Nakamura, Takashi, E-mail: ntakashi@tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 1,1 Katahira, 2-Chome, Sendai 980-8577 (Japan)

    2013-09-15T23:59:59.000Z

    Highlights: • Copper, silver and gold during thermal treatment with brominated flame retardants. • Distribution of copper, silver and gold during thermal processing. • Thermodynamic considerations of the bromination reactions. - Abstract: The growing consumption of electric and electronic equipment results in creating an increasing amount of electronic waste. The most economically and environmentally advantageous methods for the treatment and recycling of waste electric and electronic equipment (WEEE) are the thermal techniques such as direct combustion, co-combustion with plastic wastes, pyrolysis and gasification. Nowadays, this kind of waste is mainly thermally treated in incinerators (e.g. rotary kilns) to decompose the plastics present, and to concentrate metals in bottom ash. The concentrated metals (e.g. copper, precious metals) can be supplied as a secondary raw material to metal smelters, while the pyrolysis of plastics allows the recovery of fuel gases, volatilising agents and, eventually, energy. Indeed, WEEE, such as a printed circuit boards (PCBs) usually contains brominated flame retardants (BFRs). From these materials, hydrobromic acid (HBr) is formed as a product of their thermal decomposition. In the present work, the bromination was studied of copper, silver and gold by HBr, originating from BFRs, such as Tetrabromobisphenol A (TBBPA) and Tetrabromobisphenol A-Tetrabromobisophenol A diglycidyl ether (TTDE) polymer; possible volatilization of the bromides formed was monitored using a thermo-gravimetric analyzer (TGA) and a laboratory-scale furnace for treating samples of metals and BFRs under an inert atmosphere and at a wide range of temperatures. The results obtained indicate that up to about 50% of copper and silver can evolve from sample residues in the form of volatile CuBr and AgBr above 600 and 1000 °C, respectively. The reactions occur in the molten resin phase simultaneously with the decomposition of the brominated resin. Gold is resistant to HBr and remains unchanged in the residue.

  17. Chemiluminescence-based multivariate sensing of local equivalence ratios in premixed atmospheric methane-air flames

    SciTech Connect (OSTI)

    Tripathi, Markandey M.; Krishnan, Sundar R.; Srinivasan, Kalyan K.; Yueh, Fang-Yu; Singh, Jagdish P.

    2012-03-01T23:59:59.000Z

    Chemiluminescence emissions from OH*, CH*, C2, and CO2 formed within the reaction zone of premixed flames depend upon the fuel-air equivalence ratio in the burning mixture. In the present paper, a new partial least square regression (PLS-R) based multivariate sensing methodology is investigated and compared with an OH*/CH* intensity ratio-based calibration model for sensing equivalence ratio in atmospheric methane-air premixed flames. Five replications of spectral data at nine different equivalence ratios ranging from 0.73 to 1.48 were used in the calibration of both models. During model development, the PLS-R model was initially validated with the calibration data set using the leave-one-out cross validation technique. Since the PLS-R model used the entire raw spectral intensities, it did not need the nonlinear background subtraction of CO2 emission that is required for typical OH*/CH* intensity ratio calibrations. An unbiased spectral data set (not used in the PLS-R model development), for 28 different equivalence ratio conditions ranging from 0.71 to 1.67, was used to predict equivalence ratios using the PLS-R and the intensity ratio calibration models. It was found that the equivalence ratios predicted with the PLS-R based multivariate calibration model matched the experimentally measured equivalence ratios within 7%; whereas, the OH*/CH* intensity ratio calibration grossly underpredicted equivalence ratios in comparison to measured equivalence ratios, especially under rich conditions ( > 1.2). The practical implications of the chemiluminescence-based multivariate equivalence ratio sensing methodology are also discussed.

  18. Stability and Complexity in

    E-Print Network [OSTI]

    Landweber, Laura

    and complexity of a commu- nity of interacting plants and animals, following the food web as a clue. Contrary in power. Stability and Complexity in Model Ecosystems played a key role in introducing nonlinear thinking, and current threats to biodiversity have made questions about the role of ecosystem complexity

  19. Stabilized chromium oxide film

    DOE Patents [OSTI]

    Garwin, Edward L. (Los Altos, CA); Nyaiesh, Ali R. (Palo Alto, CA)

    1988-01-01T23:59:59.000Z

    Stabilized air-oxidized chromium films deposited on high-power klystron ceramic windows and sleeves having a thickness between 20 and 150.ANG. are useful in lowering secondary electron emission yield and in avoiding multipactoring and window failure due to overheating. The ceramic substrate for the film is chosen from alumina, sapphire or beryllium oxide.

  20. Stabilized chromium oxide film

    DOE Patents [OSTI]

    Nyaiesh, A.R.; Garwin, E.L.

    1986-08-04T23:59:59.000Z

    Stabilized air-oxidized chromium films deposited on high-power klystron ceramic windows and sleeves having a thickness between 20 and 150A are useful in lowering secondary electron emission yield and in avoiding multipactoring and window failure due to overheating. The ceramic substrate for the film is chosen from alumina, sapphire or beryllium oxide.