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1

Effects of buoyancy on premixed flame stabilization  

Science Conference Proceedings (OSTI)

The stabilization limits of v-flame and conical flames are investigated in normal gravity (+g) and reversed gravity (up-side-down burner, -g) to compare with observations of flame stabilization during microgravity experiments. The results show that buoyancy has most influence on the stabilization of laminar V-flames. Under turbulent conditions, the effects are less significant. For conical flames stabilized with a ring, the stabilization domain of the +g and -g cases are not significantly different. Under reversed gravity, both laminar v-flames and conical flames show flame behaviors that were also found in microgravity. The v-flames reattached to the rim and the conical flame assumed a top-hat shape. One of the special cases of -g conical flame is the buoyancy stabilized laminar flat flame that is detached from the burner. These flame implies a balance between the flow momentum and buoyant forces. The stretch rates of these flames are sufficiently low (laminar burning speed S{sub L}{sup 0}. An analysis based on evaluating the Richardson number is used to determine the relevant parameters that describe the buoyancy/momentum balance. A perfect balance i.e. Ri = l can be attained when the effect of heat loss from the flame zone is low. For the weaker lean cases, our assumption of adiabaticity tends to overestimate the real flame temperature. This interesting low stretch laminar flame configuration can be useful for fundamental studies of combustion chemistry.

Bedat, B.; Cheng, R.K.

1995-10-01T23:59:59.000Z

2

Effects of buoyancy on premixed flame stabilization  

SciTech Connect

The stabilization limits of v-flame and conical flames are investigated in normal gravity (+g) and reversed gravity (up-side-down burner, -g) to compare with observations of flame stabilization during microgravity experiments. The results show that buoyancy has most influence on the stabilization of laminar V-flames. Under turbulent conditions, the effects are less significant. For conical flames stabilized with a ring, the stabilization domain of the +g and -g cases are not significantly different. Under reversed gravity, both laminar v-flames and conical flames show flame behaviors that were also found in microgravity. The v-flames reattached to the rim and the conical flame assumed a top-hat shape. One of the special cases of -g conical flame is the buoyancy stabilized laminar flat flame that is detached from the burner. These flame implies a balance between the flow momentum and buoyant forces. The stretch rates of these flames are sufficiently low (< 20 s{sup -1}) such that the displacement speeds S{sub L} are almost equal to the laminar burning speed S{sub L}{sup 0}. An analysis based on evaluating the Richardson number is used to determine the relevant parameters that describe the buoyancy/momentum balance. A perfect balance i.e. Ri = l can be attained when the effect of heat loss from the flame zone is low. For the weaker lean cases, our assumption of adiabaticity tends to overestimate the real flame temperature. This interesting low stretch laminar flame configuration can be useful for fundamental studies of combustion chemistry.

Bedat, B.; Cheng, R.K.

1995-10-01T23:59:59.000Z

3

Flame stabilizer for stagnation flow reactor  

DOE Patents (OSTI)

A method of stabilizing a strained flame in a stagnation flow reactor. By causing a highly strained flame to be divided into a large number of equal size segments it is possible to stablize a highly strained flame that is on the verge of extinction, thereby providing for higher film growth rates. The flame stabilizer is an annular ring mounted coaxially and coplanar with the substrate upon which the film is growing and having a number of vertical pillars mounted on the top surface, thereby increasing the number of azimuthal nodes into which the flame is divided and preserving an axisymmetric structure necessary for stability.

Hahn, David W. (Dublin, CA); Edwards, Christopher F. (Sunnyvale, CA)

1999-01-01T23:59:59.000Z

4

Laser controlled flame stabilization  

DOE Patents (OSTI)

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.

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

2001-01-01T23:59:59.000Z

5

Lean Premixed Flame Stability Investigations  

E-Print Network (OSTI)

Fellowship Experience Throughout my twelve-week fellowship at Pratt & Whitney I had the opportunity to interact with numerous engineers and managers as well as to be exposed to a variety of disciplines and areas of engineering. My mentor, Bill Proscia, is an expert in the field of combustion instability analysis and modeling. I gained valuable experience working on a combustion project under his guidance. The project involved studying combustor aerodynamics and static stability of lean-premixed flames for two combustor geometries as a function of swirl number and fuel type. Having an almost non-existent background in the field of combustion, this was a challenging, but very rewarding project to work on. The first few weeks consisted of meeting with engineers and managers to decide on what kind of study I could conduct that would be useful to Pratt & Whitney. During this time I also was able to learn about the business side of engineering and gain a small insight into the overall infrastructure of Pratt & Whitney. In addition to these meetings much of my time was spent reading published literature as well as textbooks on combustion, methods used for modeling combustion, combustion stability, and other

Jared Crosby

2005-01-01T23:59:59.000Z

6

Freely propagating open premixed turbulent flames stabilized by swirl  

DOE Green Energy (OSTI)

A novel means has been developed for using weak swirl to stabilize freely propagating open premixed turbulent flames (swirl numbers between 0.05 to 0.3). By injecting a small amount of air tangentially into the co-flow of a concentric burner, stationary flames can be maintained above the burner exit for a large range of mixture, turbulence and flow conditions. The absence of physical surfaces in the vicinity of the flame provides free access to laser diagnostics. Laser Doppler anemometry and laser Mie scattering measurements of four flames with and without incident turbulence show that their features are typical of wrinkled laminar flames. The most distinct characteristics is that flame stabilization does not rely on flow recirculation. Centrifugal force induced by swirl causes flow divergence, and the flame is maintained at where the local mass flux balances the burning rate. The flame speeds can be estimated based on the centerline velocity vector, which is locally normal to the flame brush. This flame geometry is the closest approximation to the 1-D planar flame for determining fundamental properties to advance turbulent combustion theories. 18 refs.

Chan, C.K.; Lau, K.S.; Chin, W.K. (Hong Kong Polytechnic, Kowloon (Hong Kong)); Cheng, R.K. (Lawrence Berkeley Lab., CA (United States))

1991-12-01T23:59:59.000Z

7

Stability Regimes of Turbulent Nitrogen-Diluted Hydrogen Jet Flames  

SciTech Connect

One option for combustion in zero-emission Integrated Gasification Combined Cycle (IGCC) power plants is non-premixed combustion of nitrogen-diluted hydrogen in air. An important aspect to non-premixed combustion is flame stability or anchoring, though only a few fundamental stability studies of these flames have taken place to date. The following paper presents the results of experiments investigating the effects of nitrogen diluent fraction, jet diameter, and exit velocity on the static stability limits of a turbulent hydrogen jet flame issuing from a thin-lipped tube into a quiescent atmosphere. Four different stability limits are observed: detachment from the burner lip, reattachment to the burner lip, transition from a laminar lifted flame base to blowout or to a turbulent lifted flame, and transition from a turbulent lifted flame to blowout. The applicability of existing theories and correlations to the stability results is discussed. These results are an important step in assessing the viability of a non-premixed combustion approach using hydrogen diluted with nitrogen as a fuel.

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

2007-03-01T23:59:59.000Z

8

Flame stabilization by a plasma driven radical jet in a high speed flow .  

E-Print Network (OSTI)

??In current afterburners combustion is stabilized by the high temperature, recirculating region behind bluff body flame holders, such as V-gutters. Blocking the high speed flow… (more)

Choi, Woong-Sik

2009-01-01T23:59:59.000Z

9

Research on Stability Criterion of Furnace Flame Combustion Based on Image Processing  

Science Conference Proceedings (OSTI)

This paper proposes and analyzes the stability criterion of furnace flame combustion based on image processing, which uses the maximum criterion of gray scale difference, the distance criterion of gravity center and mass center in the high temperature ... Keywords: image processing, stability, flame detection, boiler safety

Rongbao Chen, Wuting Fan, Jingci Bian, Fanhui Meng

2012-12-01T23:59:59.000Z

10

The stabilization of a methane-air edge flame within a mixing layer in a narrow channel  

SciTech Connect

The flame stabilization mechanism of a methane-air edge flame formulated in a narrow channel was experimentally investigated and compared with a simple analytical model. Non-premixed flames were classified into premixed flame modes and edge flame modes. The correlation between the propagation velocity and the fuel concentration gradient in a narrow channel was investigated and the applicability of ordinary edge-flame theory was appraised. (author)

Lee, Min Jung; Kim, Nam Il [School of Mechanical Engineering, Chung-Ang University, Dongjak, Seoul 156-76 (Korea)

2010-01-15T23:59:59.000Z

11

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

E-Print Network (OSTI)

Natural gas is the primary fuel used in industrial gas turbines for power generation. 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 of the physical characteristics such as the laminar flame speed is necessary, especially at elevated pressures to have the most relevance to the gas turbine industry. This thesis discusses the equations governing premixed laminar flames, historical methods used to measure the laminar flame speed, the experimental device used in this study, the procedure for converting the measured data into the flame speed, the results of the measurements, and a discussion of the results. The results presented in this thesis 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 comparison between the experimental measurements and four chemical kinetic models. The C4 mechanism, developed in part through collaboration between the National University of Ireland Galway and Texas A&M, was improved using the data presented herein, showing good agreement for all cases. The effect of blending ethane, propane, and dimethyl ether with methane in binary form is emphasized in this study, with the resulting Markstein length, Lewis number (Le), and flame stability characterized and discussed. It was noticed in this study, as well as in other studies, that the critical radius of the flame typically decreased as the Le decreased, and that the critical radius of the flame increased as the Le increased. Also, a rigorous uncertainty analysis has been performed, showing a range of 0.3 cm/s to 3.5 cm/s depending on equivalence ratio and initial pressure.

Lowry, William Baugh

2010-12-01T23:59:59.000Z

12

Numerical simulations of perforated plate stabilized premixed flames with detailed chemistry  

E-Print Network (OSTI)

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 ...

Kedia, Kushal Sharad

2010-01-01T23:59:59.000Z

13

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

E-Print Network (OSTI)

??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… (more)

Kedia, Kushal Sharad

2010-01-01T23:59:59.000Z

14

Mechanisms of Flame Stabilization and Blowout in a Reacting Turbulent Hydrogen Jet in Cross-Flow  

SciTech Connect

The mechanisms contributing to flame stabilization and blowout in a nitrogen-diluted hydrogen transverse jet in a turbulent boundary layer cross-flow (JICF) are investigated using three-dimensional direct numerical simulation (DNS) with detailed chemistry. Non-reacting JICF DNS were performed to understand the relative magnitude and physical location of low velocity regions on the leeward side of the fuel jet where a flame can potentially anchor. As the injection angle is reduced from 90{sup o} to 70{sup o}, the low velocity region was found to diminish significantly, both in terms of physical extent and magnitude, and hence, its ability to provide favorable conditions for flame anchoring and stabilization are greatly reduced. In the reacting JICF DNS a stable flame is observed for 90{sup o} injection angle and, on average, the flame root is in the vicinity of low velocity magnitude and stoichiometric mixture. When the injection angle is smoothly transitioned to 75{sup o} a transient flame blowout is observed. Ensemble averaged quantities on the flame base reveal two phases of the blowout characterized by a kinematic imbalance between flame propagation speed and flow normal velocity. In the first phase dominant flow structures repeatedly draw the flame base closer to the jet centerline resulting in richer-than-stoichiometric mixtures and high velocity magnitudes. In the second phase, in spite of low velocity magnitudes and a return to stoichiometry, due to jet bending and flame alignment normal to the cross-flow, the flow velocity normal to the flame base increases dramatically perpetuating the blowout.

Kolla, H.; Grout, R. W.; Gruber, A.; Chen, J. H.

2012-08-01T23:59:59.000Z

15

A DNS study on the stabilization mechanism of a turbulent lifted ethylene jet flame in highly-heated coflow  

SciTech Connect

Direct numerical simulation (DNS) of the near-field of a three-dimensional spatially-developing turbulent ethylene jet flame in highly-heated coflow is performed with a reduced mechanism to determine the stabilization mechanism. The DNS was performed at a jet Reynolds number of 10,000 with over 1.29 billion grid points. The results show that auto-ignition in a fuel-lean mixture at the flame base is the main source of stabilization of the lifted jet flame. The Damkoehler number and chemical explosive mode (CEM) analysis also verify that auto-ignition occurs at the flame base. In addition to auto-ignition, Lagrangian tracking of the flame base reveals the passage of large-scale flow structures and their correlation with the fluctuations of the flame base similar to a previous study (Yoo et al., J. Fluid Mech. 640 (2009) 453-481) with hydrogen/air jet flames. It is also observed that the present lifted flame base exhibits a cyclic 'saw-tooth' shaped movement marked by rapid movement upstream and slower movement downstream. This is a consequence of the lifted flame being stabilized by a balance between consecutive auto-ignition events in hot fuel-lean mixtures and convection induced by the high-speed jet and coflow velocities. This is confirmed by Lagrangian tracking of key variables including the flame-normal velocity, displacement speed, scalar dissipation rate, and mixture fraction at the stabilization point.

Yoo, Chun S [Sandia National Laboratories (SNL)

2011-01-01T23:59:59.000Z

16

Flame Response Mechanisms and their Interaction in a Lean Premixed Swirl-Stabilized Gas Turbine Combustor.  

E-Print Network (OSTI)

??To satisfy increasingly stringent environmental regulations, gas turbine engines are run in a lean premixed mode. Unfortunately, operating in this mode greatly increases the flame’s… (more)

Jones, Brian

2011-01-01T23:59:59.000Z

17

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

Science Conference Proceedings (OSTI)

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.

Law, Chung K.

1999-07-01T23:59:59.000Z

18

Visualization of Multiple Scalar and Velocity Fields in a Lifted Jet Flame  

Science Conference Proceedings (OSTI)

The stabilization of lifted jet diffusion flames has long been a topic of interest to combustion researchers. The flame and flow morphology, the role of partial premixing, and the effects of large scale structures on the flame can be visualized through ... Keywords: Rayleigh scattering, combustion, flame stabilization, jet diffusion flame, laser diagnostics, laser-induced fluorescence (LIF), particle image velocimetry (PIV)

K. A. Watson; K. M. Lyons; J. M. Donbar; C. D. Carter

2000-08-01T23:59:59.000Z

19

FLAME STRUCTURE MEASUREMENT OF POLYMER DIFFUSION FLAMES  

E-Print Network (OSTI)

of counterflow diffusion flames above condensed fuels:of counterflow diffusion flames in the forward stagnationCA, October 15-16, 1979 FLAME STRUCTURE MEASUREMENT OF

Pitz, W. J.

2011-01-01T23:59:59.000Z

20

Measurement of gas temperature field in a flame spreading over solid fuel.  

E-Print Network (OSTI)

??An experimental measurement is developed to measure the gas temperature field in a flame spreading downward over thermally thin filter paper. A flame stabilizer apparatus… (more)

Alghamdi, Abdulaziz Othman

2012-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Investigating the Flame Microstructure in Type Ia Supernovae  

E-Print Network (OSTI)

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.

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

2002-04-02T23:59:59.000Z

22

FLAT FLAME BURNER ANALYSES  

E-Print Network (OSTI)

J. C. , Combustion and Flame 34, pp. 85-98 (1979). Carrier.Effects on a One-Dimensional Flame," Combust. Sci. and Tech.Uniformity in Edge Cooled F1at Flame Burners," Combust. Sci.

Pagni, P.J.

2012-01-01T23:59:59.000Z

23

Active control for turbulent premixed flame simulations  

Science Conference Proceedings (OSTI)

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.

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

2004-03-26T23:59:59.000Z

24

Experimental study of premixed flames in intense isotropic turbulence  

SciTech Connect

A methodology for investigating premixed turbulent flames propagating in intense isotropic turbulence has been developed. The burner uses a turbulence generator developed by Videto and Santavicca and the flame is stabilized by weak-swirl generated by air injectors. This set-up produces stable premixed turbulent flames under a wide range of mixture conditions and turbulence intensities. The experiments are designed to investigate systematically the changes in flame structures for conditions which can be classified as wrinkled laminar flames, corrugated flames and flames with distributed reaction zones. Laser Doppler anemometry and Rayleigh scattering techniques are used to determine the turbulence and scalar statistics. In the intense turbulence, the flames are found to produce very little changes in the mean and rams velocities. Their flame speed increase linearly with turbulence intensity as for wrinkled laminar flames. The Rayleigh scattering pdfs for flames within the distributed reaction zone regime are distinctly bimodal. The probabilities of the reacting states (i.e. contributions from within the reaction zone) is not higher than those of wrinkled laminar flame. These results show that there is no drastic changes in flame structures at Karlovitz number close to unity. This suggest that the Klimov-Williams criterion under-predicts the resilience of wrinkled flamelets to intense turbulence.

Bedat, B.; Cheng, R.K.

1994-04-01T23:59:59.000Z

25

Flame transfer function measurements and mechanisms in a single-nozzle combustor.  

E-Print Network (OSTI)

??The response of a fully-premixed flame to velocity fluctuations was experimentally measured in a single-nozzle, swirl-stabilized, model gas turbine combustor. Flame response was quantified in… (more)

Bunce, Nicholas

2013-01-01T23:59:59.000Z

26

Oscillation and extinction in flames.  

E-Print Network (OSTI)

?? Oscillation phenomena in flames were theoretically investigated for both diffusion and premixed flames. For diffusion flames, oscillations develop intrinsically as a result of thermal-diffusive… (more)

Wang, Heyang

2008-01-01T23:59:59.000Z

27

Studies on upward flame spread  

E-Print Network (OSTI)

5.7 Flame Heights . . . . . . . . . . . . . . . . . .3.4.1 Flame Heights . . . . . . . . . . . . . . 3.5Chapter 4 Upward Flame Spread of an Inclined Fuel Surface

Gollner, Michael J.

2012-01-01T23:59:59.000Z

28

Active Control for Statistically Stationary Turbulent PremixedFlame Simulations  

Science Conference Proceedings (OSTI)

The speed of propagation of a premixed turbulent flame correlates with the intensity of the turbulence encountered by the flame. One consequence of this property is that premixed flames in both laboratory experiments and practical combustors require some type of stabilization mechanism 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. Furthermore, the stabilization introduces additional fluid mechanical complexity into the overall combustion process that can complicate the analysis of fundamental flame properties. To circumvent these difficulties we introduce a feedback control algorithm that allows us to computationally stabilize a turbulent premixed flame in a simple geometric configuration. For the simulations, we specify turbulent inflow 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 on methane flames at various equivalence ratios in two dimensions. The simulation data are used to study the local variation in the speed of propagation due to flame surface curvature.

Bell, J.B.; Day, M.S.; Grcar, J.F.; Lijewski, M.J.

2005-08-30T23:59:59.000Z

29

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30

FLAME STRUCTURE MEASUREMENT OF POLYMER DIFFUSION FLAMES  

E-Print Network (OSTI)

diffusion flame of gaseous propane and methane provide aCurrent study Tsuji and Yamoaka (propane fuel, -f Oxidizeris air and propane flow rate is constant Nozzle velocity

Pitz, W. J.

2011-01-01T23:59:59.000Z

31

Method of growing films by flame synthesis using a stagnation-flow reactor  

DOE Patents (OSTI)

A method of stabilizing a strained flame in a stagnation flow reactor. By causing a highly strained flame to be divided into a large number of equal size segments it is possible to stablize a highly strained flame that is on the verge of extinction, thereby providing for higher film growth rates. The flame stabilizer is an annular ring mounted coaxially and coplanar with the substrate upon which the film is growing and having a number of vertical pillars mounted on the top surface, thereby increasing the number of azimuthal nodes into which the flame is divided and preserving an axisymmetric structure necessary for stability.

Hahn, David W. (Dublin, CA); Edwards, Christopher F. (Sunnyvale, CA)

1998-01-01T23:59:59.000Z

32

Method of growing films by flame synthesis using a stagnation-flow reactor  

DOE Patents (OSTI)

A method is described for stabilizing a strained flame in a stagnation flow reactor. By causing a highly strained flame to be divided into a large number of equal size segments it is possible to stablize a highly strained flame that is on the verge of extinction, thereby providing for higher film growth rates. The flame stabilizer is an annular ring mounted coaxially and coplanar with the substrate upon which the film is growing and having a number of vertical pillars mounted on the top surface, thereby increasing the number of azimuthal nodes into which the flame is divided and preserving an axisymmetric structure necessary for stability. 5 figs.

Hahn, D.W.; Edwards, C.F.

1998-11-24T23:59:59.000Z

33

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

Science Conference Proceedings (OSTI)

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

Grcar, Joseph F; Grcar, Joseph F

2008-06-30T23:59:59.000Z

34

Flame Height Measurement of Laminar Inverse Diffusion Flames  

E-Print Network (OSTI)

Shin, E.J. Lee, Combust. Flame 140 (3) (2005) 249-254. [8].Du, R.L. Axelbaum, Combust. Flame 100 (3) (1995) 367-375. [A.C. Cunningham, Combust. Flame 29 (1977) 227-234. [13].

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

2006-01-01T23:59:59.000Z

35

Studies on upward flame spread  

E-Print Network (OSTI)

and A. Alkidas. Combustion of wood in methanol flames.of wet and dry wood by radiation. Combustion and Flame, 11(

Gollner, Michael J.

2012-01-01T23:59:59.000Z

36

Studies on upward flame spread.  

E-Print Network (OSTI)

??Experimental techniques have been used to investigate three upward flame spread phenomena of particular importance for fire safety applications. First, rates of upward flame spread… (more)

Gollner, Michael J.

2012-01-01T23:59:59.000Z

37

Effects of buoyancy on the flowfields of lean premixed turbulentv-flames  

SciTech Connect

Open laboratory turbulent flames used for investigating fundament flame turbulence interactions are greatly affected by buoyancy. Though much of our current knowledge is based on observations made in these open flames, the effects of buoyancy are usually not included in data interpretation, numerical analysis or theories. This inconsistency remains an obstacle to merging experimental observations and theoretical predictions. To better understanding the effects of buoyancy, our research focuses on steady lean premixed flames propagating in fully developed turbulence. We hypothesize that the most significant role of buoyancy forces on these flames is to influence their flowfields through a coupling with mean and fluctuating pressure fields. Changes in flow pattern alter the mean aerodynamic stretch and in turn affect turbulence fluctuation intensities both upstream and downstream of the flame zone. Consequently, flame stabilization, reaction rates, and turbulent flame processes are all affected. This coupling relates to the elliptical problem that emphasizes the importance of the upstream, wall and downstream boundary conditions in determining all aspects of flame propagation. Therefore, buoyancy has the same significance as other parameters such as flow configuration, flame geometry, means of flame stabilization, flame shape, enclosure size, mixture conditions, and flow conditions.

Cheng, R.K.; Bedat, B.; Yegian, D.T.; Greenberg, P.

2001-03-01T23:59:59.000Z

38

Propagation of premixed flames in confined channels.  

E-Print Network (OSTI)

??The propagation of premixed flames in confined channels is investigated. In the unconfined case, the structure of the flame and the flame speed for the… (more)

Navaneetha, Arjun

2013-01-01T23:59:59.000Z

39

Virtual Tour  

Science Conference Proceedings (OSTI)

*. Bookmark and Share. EBIT Laboratory. EBIT Laboratory Virtual Tour. Click one of the six movies below to download, then ...

2010-10-05T23:59:59.000Z

40

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

Science Conference Proceedings (OSTI)

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

Choi, B.C.; Chung, S.H. [Clean Combustion Research Center, King Abdullah University of Science and Technology, Thuwal (Saudi Arabia)

2010-12-15T23:59:59.000Z

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

A mechanistic study of Soret diffusion in hydrogen-air flames  

Science Conference Proceedings (OSTI)

The separate and combined effects of Soret diffusion of the hydrogen molecule (H{sub 2}) and radical (H) on the structure and propagation speed of the freely-propagating planar premixed flames, and the strain-induced extinction response of premixed and nonpremixed counterflow flames, were computationally studied for hydrogen-air mixtures using a detailed reaction mechanism and transport properties. Results show that, except for the conservative freely-propagating planar flame, Soret diffusion of H{sub 2} increases the fuel concentration entering the flame structure and as such modifies the mixture stoichiometry and flame temperature, which could lead to substantial increase (decrease) of the flame speed for the lean (rich) mixtures respectively. On the other hand, Soret diffusion of H actively modifies its concentration and distribution in the reaction zone, which in turn affects the individual reaction rates. In particular, the reaction rates of the symmetric, twin, counterflow premixed flames, especially at near-extinction states, can be increased for lean flames but decreased for rich flames, whose active reaction regions are respectively located at, and away from, the stagnation surface. However, such a difference is eliminated for the single counterflow flame stabilized by an opposing cold nitrogen stream, as the active reaction zone up to the state of extinction is always located away from the stagnation surface. Finally, the reaction rate is increased in general for diffusion flames because the bell-shaped temperature distribution localizes the H concentration to the reaction region which has the maximum temperature. (author)

Yang, F. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States); Department of Engineering Mechanics, Tsinghua University, Beijing (China); Law, C.K. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States); Sung, C.J. [Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269 (United States); Zhang, H.Q. [Department of Engineering Mechanics, Tsinghua University, Beijing (China)

2010-01-15T23:59:59.000Z

42

Flame Doctor for Cyclone Boilers  

Science Conference Proceedings (OSTI)

This development program was designed to enhance monitoring and diagnostic technology for cyclone furnaces using the Flame Doctor combustion diagnostic system. First developed for wall-fired pulverized-coal burner systems and boilers, Flame Doctor allows simultaneous, continuous monitoring and evaluation of each burner in a boiler using signals from optical flame scanners. An initial feasibility test conducted at the AmerenUE Sioux cyclone boiler indicated Flame Doctor technology could be extended to cyc...

2007-12-12T23:59:59.000Z

43

The Soret Effect in Naturally Propagating, Premixed, Lean, Hydrogen-Air Flames  

SciTech Connect

Comparatively little attention has been given to multicomponent diffusion effects in lean hydrogen-air flames, in spite of the importance of these flames in safety and their potential importance to future energy technologies. Prior direct numerical simulations either have considered only the mixture-averaged transport model, or have been limited to stabilized flames that do not exhibit the thermo-diffusive instability. The so-called full, multicomponent transport model with cross-diffusion is found to predict hotter, significantly faster flames with much faster extinction and division of cellular structures.

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

2008-06-30T23:59:59.000Z

44

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

E-Print Network (OSTI)

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.

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

2003-12-03T23:59:59.000Z

45

Lean Flame Stabilization Ring - Lawrence Berkeley National ...  

Robert Cheng at Berkeley National Laboratory has developed a means for retrofitting existing burners to burn lean, premixed natural gas/air mixtures ...

46

Lean Flame Stabilization Ring - Energy Innovation Portal  

Vehicles and Fuels; Wind Energy; ... premixed natural gas/air mixtures to reduce NOx emissions without sacrificing efficiency and burner design ... ...

47

An Experimental Study of Flame Response Mechanisms in a Lean-premixed Gas Turbine Combustor.  

E-Print Network (OSTI)

??The heat release rate response of a swirl-stabilized, turbulent, lean-premixed natural gas-air flame to velocity oscillations was investigated in an atmospheric variable length research combustor… (more)

Peluso, Stephen

2012-01-01T23:59:59.000Z

48

Liftoff and blowoff of a diffusion flame between parallel streams of fuel and air  

SciTech Connect

A numerical analysis is presented to describe the liftoff and blowoff of a diffusion flame in the mixing layer between two parallel streams of fuel (mainly methane diluted with nitrogen) and air emerging from porous walls. The analysis, which takes into account the effects of thermal expansion, assumes a one-step overall Arrhenius reaction, where the activation energy E is allowed to vary to reproduce the variations of the planar flame propagation velocity with the equivalence ratio. First, we describe the steady flame-front structure when stabilized close to the porous wall (attached flame regime). Then, we analyze the case where the flame front is located far away from the porous wall, at a distance x{sub f}' such that, upstream of the flame front, the mixing layer has a self-similar structure (lifted flame regime). For steady lifted flames, the results, given here in the case when the fuel and air streams are injected with the same velocity, relate U{sub f}'/S{sub L}, the front velocity (relative to the upstream flow) measured with the planar stoichiometric flame velocity, with the Damkohler number D{sub m}=({delta}{sub m}/{delta}{sub L}){sup 2}, based on the thickness, {delta}{sub m}, of the nonreacting mixing layer at the flame-front position and the laminar flame thickness, {delta}{sub L}. For large values of D{sub m}, the results, presented here for a wide range of dilutions of the fuel stream, provide values of the front propagation velocity that are in good agreement with previous experimental results, yielding well-defined conditions for blowoff. The calculated flame-front velocity can also be used to describe the transient flame-front dynamics after ignition by an external energy source.

Fernandez-Tarrazo, Eduardo [I.N.T.A. Area de Propulsion-Edificio R02, Ctra. Ajalvir, km 4, 28850 Torrejon de Ardoz, Madrid (Spain); Vera, Marcos [Area de Mecanica de Fluidos, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Linan, Amable [Departamento de Motopropulsion y Termofluidodinamica, Universidad Politecnica de Madrid, Pza. Cardenal Cisneros 3, 28040 Madrid (Spain)

2006-01-01T23:59:59.000Z

49

The role of in situ reforming in plasma enhanced ultra lean premixed methane/air flames  

Science Conference Proceedings (OSTI)

This paper describes a mechanism for the stabilization of ultra lean premixed methane/air flames by pulsed nonequilibrium plasma enhancement. It is shown that the pulsed discharge plasma produces a cool ({proportional_to}500-600 K) stream of relatively stable intermediate species including hydrogen (H{sub 2}) and carbon monoxide (CO), which play a central role in enhancing flame stability. This stream is readily visualized by ultraviolet emission from electronically excited hydroxyl (OH) radicals. The rotational and vibrational temperature of this ''preflame'' are determined from its emission spectrum. Qualitative imaging of the overall flame structure is obtained by planar laser-induced fluorescence measurements of OH. Preflame nitric oxide (NO) concentrations are determined by gas sampling chromatography. A simple numerical model of this plasma enhanced premixed flame is proposed that includes the generation of the preflame through plasma activation, and predicts the formation of a dual flame structure that arises when the preflame serves to pilot the combustion of the surrounding non-activated premixed flow. The calculation represents the plasma through its ability to produce an initial radical yield, which serves as a boundary condition for conventional flame simulations. The simulations also capture the presence of the preflame and the dual flame structure, and predict preflame levels of NO comparable to those measured. A subsequent pseudo-sensitivity analysis of the preflame shows that flame stability is most sensitive to the concentrations of H{sub 2} and CO in the preflame. As a consequence of the role of H{sub 2} and CO in enhancing the flame stability, the blowout limit extensions of methane/air and hydrogen/air mixtures in the absence/presence of a discharge are investigated experimentally. For methane/air mixtures, the blowout limit of the current burner is extended by {proportional_to}10% in the presence of a discharge while comparable studies carried out in lean hydrogen/air flames fail to extend this limit. (author)

Kim, Wookyung; Godfrey Mungal, M.; Cappelli, Mark A. [Mechanical Engineering Department, Stanford University, Bldg. 520, Stanford, CA 94305-3032 (United States)

2010-02-15T23:59:59.000Z

50

Active control for turbulent premixed flame simulations  

E-Print Network (OSTI)

Poinsot, T. J. , Combust. Flame, 121:395–417 [8] Trouve, A.Rutland, C. J. , Combust. Flame, 102:447–461 (1995). [10]Control for Turbulent Premixed Flame Simulations J. B. Bell,

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

2004-01-01T23:59:59.000Z

51

Structure of Laminar Sooting Inverse Diffusion Flames  

E-Print Network (OSTI)

Drop down lines indicate stoichiometric flame height.A.F. Sarofim, Combust. Flame 146 (1-2) (2006) 52-62. [26].J.H. Miller, Combust. Flame 79 (3-4 ) [28]. K.C. Smyth, J.H.

Mikofski, Mark A

2007-01-01T23:59:59.000Z

52

Laser Extinction in Laminar Inverse Diffusion Flames  

E-Print Network (OSTI)

Smyth, Combustion and Flame 99 (3-4 ) [11]. M.A. Mikofski,R.A. Dobbins, Combustion and Flame 51 (2) [8]. C.R.K.C. Smyth, Combustion and Flame 107 (4) (1996) 418-452. [

Macko, Kevin; Mikofski, Mark A; Fernandez-Pello, Carlos; Blevins, Linda G; Davis, Ronald W.

2005-01-01T23:59:59.000Z

53

Displacement speeds in turbulent premixed flame simulations  

E-Print Network (OSTI)

Wycko?, P. S. , Combust. Flame, 110(1–2):92–112 (1997). [9]Carter, C. D. , Combust. Flame, 133(3):323–334 (2003). [12]and Faeth, G. M. , Combust. Flame, 95:410–425 (1993). [15

Day, Marcus S.; Shepherd, Ian G.; Bell, J.; Grcar, Joseph F.; Lijewski, Michael J.

2008-01-01T23:59:59.000Z

54

Diffusion Flame Measurements: Notes B  

Science Conference Proceedings (OSTI)

... Profiles in steady and flickering methane/air, ethylene/air, and propane/air diffusion flames at atmospheric pressure using an axisymmetric burner ...

2012-10-17T23:59:59.000Z

55

Diffusion Flame Measurements: Literature Citations C  

Science Conference Proceedings (OSTI)

... Partial Equilibrium in the Reaction Zone of Methane-Air Diffusion Flames; and Combustion and Flame 37:227-244 (1980). ...

2012-10-17T23:59:59.000Z

56

Developing virtual storytellers for the virtual Alhambra  

Science Conference Proceedings (OSTI)

Thanks to the technological advances in the last ten years, the recreation of 3D virtual worlds is becoming increasingly popular in several application fields. Desktop virtual reality is one of the best ways of reaching a good number of users through ... Keywords: interactive storytelling, virtual reality, virtual storyteller, virtual tourism

José L. Fuertes; Ángel L. González; Gonzalo Mariscal; Carlos Ruiz

2007-12-01T23:59:59.000Z

57

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

E-Print Network (OSTI)

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.

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

2003-12-08T23:59:59.000Z

58

Measurements of Laminar Flame Velocity for Components of Natural Gas  

E-Print Network (OSTI)

This paper presents new experimental measurements of the laminar flame velocity of components of natural gas, methane, ethane, propane, and n?butane as well as of binary and tertiary mixtures of these compounds proposed as surrogates for natural gas. These measurements have been performed by the heat flux method using a newly built flat flame adiabatic burner at atmospheric pressure. The composition of the investigated air/hydrocarbon mixtures covers a wide range of equivalence ratios, from 0.6 to 2.1, for which it is possible to sufficiently stabilize the flame. Other measurements involving the enrichment of methane by hydrogen (up to 68%) and the enrichment of air by oxygen (oxycombustion techniques) were also performed. Both empirical correlations and a detailed chemical mechanism have been proposed, the predictions being satisfactorily compared with the newly obtained experimental data under a wide range of conditions.

Patricia Dirrenberger; Hervé Le Gall; Roda Bounaceur; Olivier Herbinet; Re Glaude; Er Konnov

2013-01-01T23:59:59.000Z

59

Effects of inclined jets on turbulent oxy-flame characteristics in a triple jet burner  

Science Conference Proceedings (OSTI)

The reactants are generally injected into the industrial furnaces by jets. An effective method to act on combustion in such systems is to control the way injection jets. The present study concerns the control of turbulent flames by the jets deflection in a natural gas-oxygen burner with separated jets. The burner of 25 kW power is constituted with three aligned jets, one central natural gas jet surrounded by two oxygen jets. The principal idea is to confine the fuel jet by oxygen jets to favour the mixing in order to improve the flame stability and consequently to reduce the pollutant emissions like NO{sub x}. The flame stability and its structural properties are analyzed by the OH chemiluminescence. The Particle Image Velocimetry technique has been used to characterize the dynamic field. Results show that the control by inclined jets has a considerable effect on the dynamic behaviour and flame topology. Indeed, the control by incline of oxygen jets towards fuel jet showed a double interest: a better stabilization of flame and a significant reduction of nitrogen oxides. Measurements showed that the deflection favours the mixing and accelerates the fusion of jets allowing the flame stabilization. (author)

Boushaki, T.; Mergheni, M.A.; Sautet, J.C. [CORIA UMR 6614 CNRS-Universite et INSA de ROUEN, Avenue de l'Universite, 76 801 Saint Etienne du Rouvray, Cedex (France); Labegorre, B. [Air Liquide CRCD, Les Loges en Josas, BP 126, 78350 Jouy en Josas (France)

2008-07-15T23:59:59.000Z

60

Virtual impactor  

Science Conference Proceedings (OSTI)

A virtual impactor 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 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.

Yeh, Hsu-Chi (Albuquerque, NM); Chen, Bean T. (Albuquerque, NM); Cheng, Yung-Sung (Albuquerque, NM); Newton, George J. (Albuquerque, NM)

1988-08-30T23:59:59.000Z

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Turbulence-Flame Interactions in Type Ia Supernovae  

E-Print Network (OSTI)

Turbulence-Flame Interactions in Type Ia Supernovae A. J.Normalised time (e) Normalised flame speed Normalised time (length scale (cm) Laminar flame width Gibson scale Cell

Aspden, Andrew J; Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 50A-1148, Berkeley, CA 94720 (Authors 1, 2 & 3); Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (Author 4); Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (Author 5)

2008-01-01T23:59:59.000Z

62

Effect of Varied Air Flow on Flame Structure of Laminar Inverse Diffusion Flames  

E-Print Network (OSTI)

D.A. , Combustion and Flame, 111:185, Table 1 IDF OperatingEffect of Varied Air Flow on Flame Structure ofLaminar Inverse Diffusion Flames Western States Section/

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

2004-01-01T23:59:59.000Z

63

Flame Structure and Soot Formation in Inverse Diffusion Flames (Ph.D. Dissertation)  

E-Print Network (OSTI)

Lindsey, D.H. Napier, Combust. Flame 2 (1958) 267-272. [23].26]. R.A. Dobbins, Combust. Flame 130 (3) (2002) 204-214. [Du, R.L. Axelbaum, Combust. Flame 100 (3) (1995) 367-375. [

Mikofski, Mark A

2005-01-01T23:59:59.000Z

64

Investigation of the principle of flame rectification in order to improve detection of the propane flame in absorption refrigerators.  

E-Print Network (OSTI)

?? Electrical properties of a propane flame was investigated to improve detection of the flame in absorption refrigerators. The principle of flame rectification, which uses… (more)

Möllberg, Andreas

2005-01-01T23:59:59.000Z

65

Evaluation of virtual routing appliances as routers virtual environment.  

E-Print Network (OSTI)

??A virtual routing appliance is a system for the rapid, automated management and employment of virtual networks. Virtual routing appliances utilize virtual machines to enable… (more)

Al-Amoudi, Ahmed

2008-01-01T23:59:59.000Z

66

Virtual impactor  

DOE Patents (OSTI)

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.

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

1988-08-30T23:59:59.000Z

67

On the theory of turbulent flame velocity  

E-Print Network (OSTI)

The renormalization ideas of self-similar dynamics of a strongly turbulent flame front are applied to the case of a flame with realistically large thermal expansion of the burning matter. In that case a flame front is corrugated both by external turbulence and the intrinsic flame instability. The analytical formulas for the velocity of flame propagation are obtained. It is demonstrated that the flame instability is of principal importance when the integral turbulent length scale is much larger than the cut off wavelength of the instability. The developed theory is used to analyse recent experiments on turbulent flames propagating in tubes. It is demonstrated that most of the flame velocity increase measured experimentally is provided by the large scale effects like the flame instability, and not by the small-scale external turbulence.

Vitaly Bychkov; Vyacheslav Akkerman; Arkady Petchenko

2012-10-19T23:59:59.000Z

68

Virtual Classroom | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Virtual Classroom Virtual Classroom Adobe Connect is as web conferencing tool that is being used as a virtual classroom in an ongoing pilot to conduct virtual Instructor Led...

69

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

SciTech Connect

Planar flames are intrinsically unstable in open domains due to the thermal expansion across the burning front--the Landau-Darrieus instability. This instability leads to wrinkling and growth of the flame surface, and corresponding acceleration of the flame, until it is stabilized by cusp formation. We look at the Landau-Darrieus in stability for C/O thermonuclear flames at conditions relevant to the late stages of a Type Ia supernova explosion. Two-dimensional direct numerical simulations of both single-mode and multi-mode perturbations using a low Mach number hydrodynamics code are presented. We show the effect of the instability on the flame speed as a function of both the density and domain size, demonstrate the existence of the small scale cutoff to the growth of the instability, and look for the proposed breakdown of the non-linear stabilization at low densities. The effects of curvature on the flame as quantified through measurements of the growth rate and computation of the corresponding Markstein number. While accelerations of a few percent are observed, they are too small to have any direct outcome on the supernova explosion.

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

2003-11-24T23:59:59.000Z

70

Flame spread Analysis using a Variable B-Number  

E-Print Network (OSTI)

for the Upward Laminar Spread of Flames Over Vertical FuelSurfaces," Combust. Flame, vol. 31, p. 135-148 P. J. PagniA. S. Rangwala, “A Theory of Flame Extinction based on Flame

Rangwala, Ali S.

2006-01-01T23:59:59.000Z

71

Development of a micro-FID using a diffusion flame.  

E-Print Network (OSTI)

??A micro-flame ionization detector (micro-FID) was developed operating with a diffusion flame with a folded flame structure. Unlike conventional FIDs, an air-hydrogen diffusion flame was… (more)

Kim, Jihyung

2011-01-01T23:59:59.000Z

72

PNNL: About - Virtual Tour  

NLE Websites -- All DOE Office Websites (Extended Search)

Tour PNNL Virtually Virtual Tour How to Navigate Before being directed to the tour webpage, here are few instructions on how to navigate. To move directly into the virtual tour,...

73

Virtual Prairie  

NLE Websites -- All DOE Office Websites (Extended Search)

Visualizing a Real Prairie: Visualizing a Real Prairie: Tools to Represent Your Data Site Index for ( Quadrat Study Project - Prairie Advocates Project - Online Prairie Data) You may use the virtual prairies you create in your presentation. You will need to save the screen or browser window to save the images you create. On the Macintosh, you type open apple-shift-3 to make a Picture file on the hard drive. You can edit these files with Adobe Photoshop or other image editing applications and put them in your report. On a PC with Windows 95, you can type the key combination of "print screen" and the alt key to save what you have displayed in the browser window to the clipboard and then paste it into an image editing application or directly into your report. Create a Quadrat Using Real Data.

74

Effects of Magnetic Field on Micro Flames.  

E-Print Network (OSTI)

??The effect of a gradient magnetic field on a diffusion micro flame i.e. C3H8/air flame has been systematically studied to comprehend their interaction. A non-uniform… (more)

Swaminathan, Sumathi

2005-01-01T23:59:59.000Z

75

Flame Inhibition by Ferrocene, Carbon Dioxide, and ...  

Science Conference Proceedings (OSTI)

Flame Inhibition by Ferrocene, Carbon Dioxide, and Trifluoromethane Blends: Synergistic ... a straight sided schlieren image which is captured by a ...

2012-10-23T23:59:59.000Z

76

Displacement speeds in turbulent premixed flame simulations  

SciTech Connect

The theory of turbulent premixed flames is based on acharacterization of the flame as a discontinuous surface propagatingthrough the fluid. The displacement speed, defined as the local speed ofthe flame front normal to itself, relative to the unburned fluid,provides one characterization of the burning velocity. In this paper, weintroduce a geometric approach to computing displacement speed anddiscuss the efficacy of the displacement speed for characterizing aturbulent flame.

Day, Marcus S.; Shepherd, Ian G.; Bell, J.; Grcar, Joseph F.; Lijewski, Michael J.

2007-07-01T23:59:59.000Z

77

Polyolefin-based flame retardant material  

Disclosure Number 200902239 Technology Summary ... Invention discloses a method to produce flame retardant fibers from neat and recycled ...

78

Production of fullerenic nanostructures in flames  

DOE Patents (OSTI)

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

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

1999-01-01T23:59:59.000Z

79

Production Of Fullerenic Soot In Flames  

DOE Patents (OSTI)

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

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

2000-12-19T23:59:59.000Z

80

Control of flames by tangential jet actuators in oxy-fuel burners  

Science Conference Proceedings (OSTI)

The active control of oxy-fuel flames from burners with separated jets is investigated. The control system consists of four small jet actuators, placed tangential to the exit of the main jets to generate a swirling flow. These actuators are able to modify the flow structure and to act on mixing between the reactants and consequently on the flame behavior. The burner (25 kW) is composed of separated jets, one jet of natural gas and one or two jets of pure oxygen. Experiments are conducted with three burner configurations, according to the number of jets, the jet exit velocities, and the separation distance between the jets. OH chemiluminescence measurements, particle image velocimetry, and measurements of NO{sub x} emissions are used to characterize the flow and the flame structure. Results show that the small jet actuators have a significant influence on the behavior of jets and the flame characteristics, particularly in the stabilization zone. It is shown that the control leads to a decrease in lift-off heights and to better stability of the flame. The use of jet actuators induces high jet spreading and an increase in turbulence intensity, which improves the mixing between the reactants and the surrounding fluid. Pollutant measurements show important results in terms of NO{sub x} reductions (up to 60%), in particular for low swirl intensity. The burner parameters, such as the number of jets and the spacing between the jets, also impact the flame behavior and NO{sub x} formation. (author)

Boushaki, Toufik [CORIA UMR 6614 CNRS-Universite et INSA de ROUEN, Site Universitaire du Madrillet, 76801 Saint Etienne du Rouvray, Cedex (France); Universite de Toulouse-INPT-UPS, IMFT (Institut de Mecanique des Fluides de Toulouse), Allee Camille Soula, F-31400 Toulouse, Cedex (France); Sautet, Jean-Charles [CORIA UMR 6614 CNRS-Universite et INSA de ROUEN, Site Universitaire du Madrillet, 76801 Saint Etienne du Rouvray, Cedex (France); Labegorre, Bernard [Air Liquide, Centre de Recherche Claude-Delorme, Les Loges-en-Josas, B.P. 126 78354 Jouy-en-Josas, Cedex (France)

2009-11-15T23:59:59.000Z

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Numerical simulation of a laboratory-scale turbulent V-flame  

SciTech Connect

We present a three-dimensional, time-dependent simulation of a laboratory-scale rod-stabilized premixed turbulent V-flame. The simulations are performed using an adaptive time-dependent low Mach number model with detailed chemical kinetics and a mixture model for differential species diffusion. The algorithm is based on a second-order projection formulation and does not require an explicit subgrid model for turbulence or turbulence chemistry interaction. Adaptive mesh refinement is used to dynamically resolve the flame and turbulent structures. Here, we briefly discuss the numerical procedure and present detailed comparisons with experimental measurements showing that the computation is able to accurately capture the basic flame morphology and associated mean velocity field. Finally, we discuss key issues that arise in performing these types of simulations and the implications of these issues for using computation to form a bridge between turbulent flame experiments and basic combustion chemistry.

Bell, J.B.; Day, M.S.; Shepherd, I.G.; Johnson, M.; Cheng, R.K.; Grcar,J.F.; Beckner, V.E.; Lijewski, M.J.

2005-02-07T23:59:59.000Z

82

Virtual Laboratories  

E-Print Network (OSTI)

At the frontier of most areas in science, computer simulations play a central role. The traditional division of natural science into experimental and theoretical investigations is now completely outdated. Instead, theory, simulation, and experimentation form three equally essential aspects, each with its own unique flavor and challenges. Yet, education in computational science is still lagging far behind, and the number of text books in this area is minuscule compared to the many text books on theoretical and experimental science. As a result, many researchers still carry out simulations in a haphazard way, without properly setting up the computational equivalent of a well equipped laboratory. The art of creating such a virtual laboratory, while providing proper extensibility and documentation, is still in its infancy. A new approach is described here, Open Knowledge, as an extension of the notion of Open Source software. Besides open source code, manuals, and primers, an open knowledge project provides simulated dialogues between code developers, thus sharing not only the code, but also the motivations behind the code.

Piet Hut

2006-10-07T23:59:59.000Z

83

The metaplastic virtual spaces  

Science Conference Proceedings (OSTI)

Virtual reality systems need new metaphors for their communication. This paper presents a fuzzy enhanced semantic virtual space model. The application of the model tries to improve its conceptualization and definition of a new virtual world system. The ... Keywords: fuzzy, metaphysical, semantic spaces, synaesthesia, virtual reality

Gianluca Mura

2007-09-01T23:59:59.000Z

84

Deeply Virtual Neutrino Scattering  

SciTech Connect

We investigate the extension of the deeply virtual Compton scattering process into the weak interaction sector.

Ales Psaker

2007-09-06T23:59:59.000Z

85

Virtual button interface  

DOE Patents (OSTI)

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.

Jones, Jake S. (Albuquerque, NM)

1999-01-01T23:59:59.000Z

86

Virtual button interface  

DOE Patents (OSTI)

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.

Jones, J.S.

1999-01-12T23:59:59.000Z

87

Virtual PCR  

Science Conference Proceedings (OSTI)

The polymerase chain reaction (PCR) stands among the keystone technologies for analysis of biological sequence data. PCR is used to amplify DNA, to generate many copies from as little as a single template. This is essential, for example, in processing forensic DNA samples, pathogen detection in clinical or biothreat surveillance applications, and medical genotyping for diagnosis and treatment of disease. It is used in virtually every laboratory doing molecular, cellular, genetic, ecologic, forensic, or medical research. Despite its ubiquity, we lack the precise predictive capability that would enable detailed optimization of PCR reaction dynamics. In this LDRD, we proposed to develop Virtual PCR (VPCR) software, a computational method to model the kinetic, thermodynamic, and biological processes of PCR reactions. Given a successful completion, these tools will allow us to predict both the sequences and concentrations of all species that are amplified during PCR. The ability to answer the following questions will allow us both to optimize the PCR process and interpret the PCR results: What products are amplified when sequence mixtures are present, containing multiple, closely related targets and multiplexed primers, which may hybridize with sequence mismatches? What are the effects of time, temperature, and DNA concentrations on the concentrations of products? A better understanding of these issues will improve the design and interpretation of PCR reactions. The status of the VPCR project after 1.5 years of funding is consistent with the goals of the overall project which was scoped for 3 years of funding. At half way through the projected timeline of the project we have an early beta version of the VPCR code. We have begun investigating means to improve the robustness of the code, performed preliminary experiments to test the code and begun drafting manuscripts for publication. Although an experimental protocol for testing the code was developed, the preliminary experiments were tainted by contaminated products received from the manufacturer. Much knowledge has been gained in the development of the code thus far, but without final debugging, increasing its robustness and verifying it against experimental results, the papers which we have drafted to share our findings still require the final data necessary for publication. The following sections summarize our final progress on VPCR as it stands after 1.5 years of effort on an ambitious project scoped for a 3 year period. We have additional details of the methods than are provided here, but would like to have legal protection in place before releasing them. The result of this project, a suite of programs that predict PCR products as a function of reaction conditions and sequences, will be used to address outstanding questions in pathogen detection and forensics at LLNL. VPCR should enable scientists to optimize PCR protocols in terms of time, temperature, ion concentration, and primer sequences and concentrations, and to estimate products and error rates in advance of performing experiments. Our proposed capabilities are well ahead of all currently available technologies, which do not model non-equilibrium kinetics, polymerase extension, or predict multiple or undesired PCR products. We are currently seeking DHS funding to complete the project, at which time licensing opportunities will be explored, an updated patent application will be prepared, and a publication will be submitted. A provisional and a full patent application have already been filed (1).

Gardner, S N; Clague, D S; Vandersall, J A; Hon, G; Williams, P L

2006-02-23T23:59:59.000Z

88

Interferometric Visualization of Jet Flames  

Science Conference Proceedings (OSTI)

This paper presents visualizations of reacting, round jets of the premixed and nonpremixed type realized by using interferometry and, complementarily, direct photography. The available interferometer, proposed by Carlomagno (1986), employs low-cost components ... Keywords: coherent structures, combustion, destabilization, interferometry, jet flames

A. Stella; G. Guj; A. Mataloni

2000-01-01T23:59:59.000Z

89

Flame Doctor for Cyclone Boilers  

Science Conference Proceedings (OSTI)

NOx control and combustion optimization in cyclone boilers requires a monitoring technique that can assess the quality of combustion in the burner and barrel and provide guidance to the operator to make adjustments in the air distribution. This report describes the results through the end of 2008 of a beta demonstration of the Flame Doctor combustion diagnostic system at five working cyclone boilers.

2009-07-22T23:59:59.000Z

90

Flex-flame burner and combustion method  

DOE Patents (OSTI)

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.

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

91

Development of a New Flame Speed Vessel to Measure the Effect of Steam Dilution on Laminar Flame Speeds of Syngas Fuel Blends at Elevated Pressures and Temperatures  

E-Print Network (OSTI)

Synthetic gas, syngas, is a popular alternative fuel for the gas turbine industry, but the composition of syngas can contain different types and amounts of contaminants, such as carbon dioxide, methane, moisture, and nitrogen, depending on the industrial process involved in its manufacturing. The presence of steam in syngas blends is of particular interest from a thermo-chemical perspective as there is limited information available in the literature. This study investigates the effect of moisture content (0 ? 15% by volume), temperature (323 ? 423 K), and pressure (1 ? 10 atm) on syngas mixtures by measuring the laminar flame speed in a newly developed constant-volume, heated experimental facility. This heated vessel also broadens the experimental field of study in the authors? laboratory to low vapor pressure fuels and other vaporized liquids. The new facility is capable of performing flame speed experiments at an initial pressure as high as 30 atm and an initial temperature up to 600 K. Several validation experiments were performed to demonstrate the complete functionality of the flame speed facility. Additionally, a design-of-experiments methodology was used to study the mentioned syngas conditions that are relevant to the gas turbine industry. The design-of-experiments methodology provided the capability to identify the most influential factor on the laminar flame speed of the conditions studied. The experimental flame speed data are compared to the most up-to-date C4 mechanism developed through collaboration between Texas A&M and the National University of Ireland Galway. Along with good model agreement shown with all presented data, a rigorous uncertainty analysis of the flame speed has been performed showing an extensive range of values from 4.0 cm/s to 16.7 cm/s. The amount of carbon monoxide dilution in the fuel was shown to be the most influential factor on the laminar flame speed from fuel lean to fuel rich. This is verified by comparing the laminar flame speed of the atmospheric mixtures. Also, the measured Markstein lengths of the atmospheric mixtures are compared and do not demonstrate a strong impact from any one factor but the ratio of hydrogen and carbon monoxide plays a key role. Mixtures with high levels of CO appear to stabilize the flame structure of thermal-diffusive instability. The increase of steam dilution has only a small effect on the laminar flame speed of high-CO mixtures, while more hydrogen-dominated mixtures demonstrate a much larger and negative effect of increasing water content on the laminar flame speed.

Krejci, Michael

2012-05-01T23:59:59.000Z

92

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

Science Conference Proceedings (OSTI)

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

Kelley, A.P.; Law, C.K. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States)

2009-09-15T23:59:59.000Z

93

An Experimental Study of the Velocity-Forced Flame Response of Lean-Fremixed Multi-Nozzle Can Combustor for Gas Turbines.  

E-Print Network (OSTI)

??The velocity forced flame response of a multi-nozzle, lean-premixed, swirl-stabilized, turbulent combustor was investigated at atmospheric pressure. The purpose of this study was to analyze… (more)

Szedlmayer, Michael

2013-01-01T23:59:59.000Z

94

Interaction of Plasma Discharges with a Flame: Experimental and Numerical Study  

Science Conference Proceedings (OSTI)

This paper presents experimental results and numerical simulations of methane/air non-premixed flame under plasma assistance. Without plasma assistance, the flame blows off at a 28-30 m{center_dot}s{sup -1} bulk velocity (power around 3 kW). When the discharge is on, the flame can be maintained up to a bulk velocity of 53 m{center_dot}s{sup -1}(power around 6 kW), corresponding to +90% gain in power with only a few watt of plasma power. The plasma discharges present short duration current pulses (between 100 ns and 200 ns) and occur non-monotonically (delay between two pulses from 6x10{sup -5} s to 0.1 s). The probability density function of this occurrence is significantly influenced by the mass flow rate or the absence of flame, revealing the strong coupling of the plasma with hydrodynamic and combustion. For the numerical section of this work, we simulated the flame using a Computational Fluid Dynamics code based on Direct Numerical Simulation (direct solving of Navier-Stokes equations), and investigated the thermal and/or chemical effects of discharges on the flame stability.

Vincent-Randonnier, Axel [ONERA, French Aerospace Lab, Palaiseau, F-91761 (France); Teixeira, David [IFP, Rueil-Malmaison, F-92852 (France)

2010-10-13T23:59:59.000Z

95

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

Science Conference Proceedings (OSTI)

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)

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

96

Hot Virtual Reality Sites  

Science Conference Proceedings (OSTI)

... Further, NIST does not endorse any commercial ... Academia Clemson University's VR research and activities. ... a good section on virtual environments ...

97

Computational and experimental study of laminar flames  

Science Conference Proceedings (OSTI)

During fiscal year 1991 we have made substantial progress in both the computational and experimental portions of our research. In particular we have continued our study of non-premixed axisymmetric methane-air flames. Computer calculations of multidimensional elliptic flames with two carbon atom chemistry using a shared memory parallel computer are reported for the first time. Also laser spectroscopy of flames utilizing a neodymium laser are also reported. (GHH)

Smooke, M.; Long, M.

1991-01-01T23:59:59.000Z

98

Numerical Simulation of a Laboratory-Scale Turbulent Slot Flame  

E-Print Network (OSTI)

J. M. Don- bar, Combust. Flame 141 (2005) 1–21. [9] R. K.I. G. Shepherd, Combust. Flame 85 [10] M. J. Berger, P.Rosa- lik, Combustion and Flame 112 (1998) 342–358. [16] S.

Bell, John B.; Day, Marcus S.; Grcar, Joseph F.; Lijewski, Michael J.; Driscoll, James F.; Filatyev, Sergei A.

2006-01-01T23:59:59.000Z

99

NUMERICAL ANALYSIS OF FLOW FIELDS GENERATED BY ACCELERATING FLAMES  

E-Print Network (OSTI)

A.J. and Oppenheim, A.K. , "Initial Flame Acceleration in anGeneration of a Shock Wave by a Flame in an Explosive Gas",of Pressure Waves by Accelerating Flames", Tenth Symposium (

Kurylo, J.

2011-01-01T23:59:59.000Z

100

Circulating Flames: Sati, Bridget Cleary and the Fiery “Native Woman”  

E-Print Network (OSTI)

McIvor Circulating Flames: Sati, Bridget Cleary andwho dies in the burning flames with her husband also belongswho dies in the burning flames with her husband,” or sati,

McIvor, Charlotte A.

2008-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Counterflow Extinction of Premixed and Nonpremixed Methanol and Ethanol Flames  

E-Print Network (OSTI)

of methanol. Combustion and Flame, 25:343, 1975. [6] A. Leeand nitrogen. Combustion and Flame, 33:197–215, 1978. [4] T.Methanol and Formaldehyde Flames. Ph.d thesis, University of

Seshadri, Kalyanasundaram

2005-01-01T23:59:59.000Z

102

Active Control for Statistically Stationary Turbulent Premixed Flame Simulations  

E-Print Network (OSTI)

of the Flames . . . . . . . . . . . . . . . . 4.2 GlobalControl Parameters . 3 Controlled Methane Flames 3.1 2-step10 4 Analysis of the GRI-Mech 3.0 Flames 4.1 Appearance

Bell, J.B.; Day, M.S.; Grcar, J.F.; Lijewski, M.J.

2005-01-01T23:59:59.000Z

103

Stochastic algorithms for the analysis of numerical flame simulations  

E-Print Network (OSTI)

methane/air ?ames. Combust. Flame, 123:522–546, 2000. [7] J.reactants. Combust. Flame, 121:395–417, [21] R. Hilbert, F.ame burning rate. Combust. Flame, [29] H. N. Najm and P. S.

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

2004-01-01T23:59:59.000Z

104

A COMPUTATIONAL STUDY OF PHYSICAL AND CHEMICAL FLAME INHIBITION  

E-Print Network (OSTI)

Prothero, A. , Comb. and Flame ll, Pratt, D.T. and Bowman,in a Stoichiometric Flame INHIBITOR CONCENTRATION (molein a 1.5 Equivalence Ratio Flame INHIBITOR CONCENTRATION (

Brown, N.J.

2011-01-01T23:59:59.000Z

105

Getting `virtual' wrongs right  

Science Conference Proceedings (OSTI)

Whilst some philosophical progress has been made on the ethical evaluation of playing video games, the exact subject matter of this enquiry remains surprisingly opaque. `Virtual murder', simulation, representation and more are found in a literature yet ... Keywords: Computer games, Fiction, Interactivity, Playfulness, Virtual, Virtual murder

Robert Francis Seddon

2013-03-01T23:59:59.000Z

106

Laser Extinction in Laminar Inverse Diffusion Flames  

E-Print Network (OSTI)

Diagnostics, Chapter 9: Laser-Induced Incandescence,Laser Extinction in Laminar Inverse Diffusion Flames WesternFoundation, Arlington, VA Laser Extinction in Laminar

Macko, Kevin; Mikofski, Mark A; Fernandez-Pello, Carlos; Blevins, Linda G; Davis, Ronald W.

2005-01-01T23:59:59.000Z

107

Diffusion Flame Measurements: Literature Citations B  

Science Conference Proceedings (OSTI)

... 2-D axisymmetric geometry: Steady and time-varying methane/air, ethylene/air and propane/air flames. 1. KC Smyth, JE ...

2012-10-17T23:59:59.000Z

108

Confined superadiabatic premixed flame-flow interaction  

Science Conference Proceedings (OSTI)

Laminar premixed unity-Lewis number flames are studied numerically, to examine flow-flame interaction in a two-dimensional closed domain. Two opposed planar flame fronts are perturbed sinusoidally and allowed to develop by consuming premixed reactants. Combustion heat release leads to global pressure and temperature rise in the domain, due to confinement. A superadiabatic condition, with products temperature rising with distance behind the flame front, is observed due to stagnation pressure rise. Variations in tangential strain rate behind the perturbed flame fronts, due to flame curvature and heat release, result in a modified local superadiabatic temperature gradient in the products. These variations in temperature gradients are shown to determine the net local confinement-heating rate in the products, leading to corresponding deviations in products temperature, and the local reaction rate along the flame front. These observations, which are not consistent with one-dimensional superadiabatic stagnation flame behavior, are a direct result of the unrestrained unsteady nature of two-dimensional flame-flow interaction.

Najm, H.N.

1995-12-31T23:59:59.000Z

109

Computational and experimental study of laminar flames  

Science Conference Proceedings (OSTI)

We have begun a computational study of nonpremixed tubular methane-air flames with detailed transport and finite rate chemistry. Our multidimensional computation research has been focused primarily on determining the structure of methane-air flames with C{sub 2} chemistry. Experimentally, we have continued our investigation of axisymmetric laminar flames using laser imaging techniques. We have investigated varying the fuel/diluent ratio. In methane flames,there is a broadband fluorescence that overlaps the Raman wavelengths used to measure the concentration of major species.

Smooke, M.D.

1990-01-01T23:59:59.000Z

110

Synthesis of Spinels by Thermal Spray Flame  

Science Conference Proceedings (OSTI)

Presentation Title, Synthesis of Spinels by Thermal Spray Flame. Author(s), Oscar Jaime Restrepo, Ernesto Román Baena Murillo. On-Site Speaker (Planned ) ...

111

Fuel effects on flame lift-off under diesel conditions  

SciTech Connect

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)

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

2011-01-15T23:59:59.000Z

112

Flame Doctor Test at Alabama Power's Plant Gaston  

Science Conference Proceedings (OSTI)

This report describes the results of an evaluation conducted by the Electric Power Research Institute (EPRI) on the Flame Doctor combustion diagnostic system, a hardware and software package designed to diagnose burner performance problems in order to improve overall combustion in the boiler. The Flame Doctor uses signals of existing flame scanners to rate the characteristics of individual boiler flames. The software generates several burner performance indicatorsincluding flame diagnostic number, flame ...

2010-04-22T23:59:59.000Z

113

Flame inhibition/suppression by water mist: Droplet size ...  

Science Conference Proceedings (OSTI)

... 1. Analysis of the flame structure and critical flame ... In the present work, the inhibition of a one ... sizes, the underlying reason for the breakdown in the ...

2012-07-27T23:59:59.000Z

114

Halogen Free Flame Retardant for ABS Composite with Oxides ...  

Science Conference Proceedings (OSTI)

The irrevocable finality from flame retardant is fires protection to help safeguard of ... the oxides particles on obtain the ABS with halogen free flame retardant.

115

INVESTIGATION OF STRETCH AND CURVATURE EFFECTS ON FLAMES.  

E-Print Network (OSTI)

??Flame response on curvature is very important for understanding and predicting of both laminar and turbulent combustion. In this work, curvature effects on flames are… (more)

Wang, Peiyong

2006-01-01T23:59:59.000Z

116

Analyzing and Tracking Burning Structures in Lean Premixed Hydrogen Flames  

E-Print Network (OSTI)

hydrogen ?ames. Combustion and Flame, 156:1035–1045, 2009. [in Lean Premixed Hydrogen Flames P. -T. Bremer 1 , G. Weber

Bremer, Peer-Timo

2010-01-01T23:59:59.000Z

117

The dependence of chemistry on the inlet equivalence ratio in vortex-flame interactions [Printed LBNL report with title: The effect of stoichiometry on vortex flame interactions  

E-Print Network (OSTI)

of stoichiometry on vortex flame interactions [31] Pember,Rosalik, M . E . , Combust. Flame, 112(3):342-358 (1998).of stoichiometry on vortex flame interactions [15] Mueller,

Tonse, Shaheen R.

2011-01-01T23:59:59.000Z

118

The dependence of chemistry on the inlet equivalence ratio in vortex-flame interactions [Printed LBNL report with title: The effect of stoichiometry on vortex flame interactions  

E-Print Network (OSTI)

of stoichiometry on vortex flame interactions [31] Pember,Rosalik, M . E . , Combust. Flame, 112(3):342-358 (1998).of stoichiometry on vortex flame interactions [15] Mueller,

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

1999-01-01T23:59:59.000Z

119

Jet flames of a refuse derived fuel  

SciTech Connect

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

Weber, Roman; Kupka, Tomasz; Zajac, Krzysztof [Institute of Energy Process Engineering and Fuel Technology, Clausthal University of Technology, Agicolastrasse 4, 38 678 Clausthal-Zellerfeld (Germany)

2009-04-15T23:59:59.000Z

120

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

Science Conference Proceedings (OSTI)

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.

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

1997-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Virtual Data System on distributed virtual machines in computational grids  

Science Conference Proceedings (OSTI)

This paper presents the work of building a Grid workflow system on distributed virtual machines. A Grid Virtualisation Engine (GVE) is implemented to manage virtual machines as computing resources for Grid applications. The Virtual Data System ... Keywords: compact muon solenoid, distributed virtual machines, grid computing, grid workflow, high energy physics applications, virtual data systems

Lizhe Wang; Gregor Von Laszewski; Jie Tao; Marcel Kunze

2010-09-01T23:59:59.000Z

122

Matsushita's Virtual Kitchen  

Science Conference Proceedings (OSTI)

... Virtual Kitchen, a retail application set up in Japan to help people choose appliances and furnishings for the relatively small kitchen apartment ...

123

DOE Virtual University  

Energy.gov (U.S. Department of Energy (DOE))

The Department of Energy Virtual University (DVU) is a central venue for executing, managing, partnering and sharing corporate learning activities and programs. The DVU provides employees cost...

124

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

SciTech Connect

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)

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

125

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)

Fuel flexibility in gas turbines is of particular importance because of the main fuel source, natural gas. Blends of methane, ethane, and propane are big constituents in natural gas and consequently are of particular interest. With this level 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 currently. This thesis discusses the theory behind laminar flames; new data acquisition techniques; temperature and pressure capability improvements; measured flame speeds; and a discussion of the results including stability analysis. The measured flame speeds were those of methane, ethane, and propane fuel blends, as well as pure methane, at an elevated pressure of 5 atm and temperatures of 298 and 473 K, using a constant-volume, cylindrical combustion vessel. The current Aramco mechanism developed in conjunction with National University of Ireland Galway compared favorably with the data, while the literature data showed discrepancies at stoichiometric to rich conditions. An in-depth flame speed uncertainty analysis yielded a wide range of values from 0.5 cm/s to 21.5 cm/s. It is well known that high-pressure experiments develop flame instabilities when air is used as the oxidizer. In this study, the hydrodynamic instabilities were restrained by using a high diluent-to-oxygen ratio. The thermal-diffusive instabilities were inhibited by using helium as the diluent. To characterize this flame stability, the Markstein length and Lewis number were calculated for the presented conditions. The resultant positive Markstein lengths showed a low propensity of flame speed to flame stretch, while the larger-than-unity Lewis numbers showed the relatively higher diffusivity of helium to that of nitrogen.

Plichta, Drew

2013-05-01T23:59:59.000Z

126

DISTRIBUTED FLAMES IN TYPE Ia SUPERNOVAE  

Science Conference Proceedings (OSTI)

At a density near a few x10{sup 7} g cm{sup -3}, the subsonic burning in a Type Ia supernova (SN) enters the distributed regime (high Karlovitz number). In this regime, turbulence disrupts the internal structure of the flame, and so the idea of laminar burning propagated by conduction is no longer valid. The nature of the burning in this distributed regime depends on the turbulent Damkoehler number (Da{sub T}), which steadily declines from much greater than one to less than one as the density decreases to a few x10{sup 6} g cm{sup -3}. Classical scaling arguments predict that the turbulent flame speed s{sub T} , normalized by the turbulent intensity u-check, follows s{sub T}/u-check = Da{sub T}{sup 1/2} for Da{sub T} {approx}burns as a turbulently broadened effective unity Lewis number flame. This flame burns locally with speed s{sub l}ambda and width l{sub l}ambda, and we refer to this kind of flame as a lambda-flame. The burning becomes a collection of lambda-flames spread over a region approximately the size of the {integral} scale. While the total burning rate continues to have a well-defined average, s{sub T}{approx}u-check, the burning is unsteady. We present a theoretical framework, supported by both one-dimensional and three-dimensional numerical simulations, for the burning in these two regimes. Our results indicate that the average value of s{sub T} can actually be roughly twice u-check for Da{sub T} {approx}> 1, and that localized excursions to as much as 5 times u-check can occur. We also explore the properties of the individual flames, which could be sites for a transition to detonation when Da{sub T} {approx} 1. The lambda-flame speed and width can be predicted based on the turbulence in the star (specifically the energy dissipation rate epsilon*) and the turbulent nuclear burning timescale of the fuel tau {sup T}{sub nuc}. We propose a practical method for measuring s{sub l}ambda and l{sub l}ambda based on the scaling relations and small-scale computationally inexpensive simulations. This suggests that a simple turbulent flame model can be easily constructed suitable for large-scale distributed SNe flames. These results will be useful both for characterizing the deflagration speed in larger full-star simulations, where the flame cannot be resolved, and for predicting when detonation occurs.

Aspden, A. J.; Bell, J. B. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 50A-1148, Berkeley, CA 94720 (United States); Woosley, S. E. [Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States)

2010-02-20T23:59:59.000Z

127

Theoretical studies in spiral edge-flame propagation and particle hydrodynamics  

E-Print Network (OSTI)

Diffusion-flame stand-off distance. . . . . . . . . .Summary of experimental flame patterns observed in theSpiral Edges of Diffusion Flames in Von K´ arm´ an Swirling

Urzay, Javier

2010-01-01T23:59:59.000Z

128

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

SciTech Connect

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)

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

129

Virtual Circuits (OSCARS)  

NLE Websites -- All DOE Office Websites (Extended Search)

Virtual Circuits (OSCARS) Virtual Circuits (OSCARS) Services Overview ECS Audio/Video Conferencing Fasterdata IPv6 Network Network Performance Tools (perfSONAR) ESnet OID Registry PGP Key Service Virtual Circuits (OSCARS) OSCARS Case Study Documentation Links Hardware Requirements DOE Grids Service Transition Contact Us Technical Assistance: 1 800-33-ESnet (Inside the US) 1 800-333-7638 (Inside the US) 1 510-486-7600 (Globally) 1 510-486-7607 (Globally) Report Network Problems: trouble@es.net Provide Web Site Feedback: info@es.net Virtual Circuits (OSCARS) ESnet's On-Demand Secure Circuits and Advance Reservation System (OSCARS) provides multi-domain, high-bandwidth virtual circuits that guarantee end-to-end network data transfer performance. Originally a research concept, OSCARS has grown into a robust production service. Currently

130

Enol Intermediates Unexpectedly Found in Flames  

NLE Websites -- All DOE Office Websites (Extended Search)

Enol Intermediates Unexpectedly Found in Flames Print Enol Intermediates Unexpectedly Found in Flames Print For those studying flame chemistry and the properties of combustion intermediates by means of molecular beam mass spectrometry, the addition of tunable vacuum ultraviolet (VUV) from a synchrotron to photoionize the beam for mass spectrometry makes for a powerful technique capable of differentiating between isomers with the same molecular weight and composition. With the help of a unique experimental apparatus, an international team of American, Chinese, and German researchers has exploited this selectivity to identify chemical compounds known as enols as apparently ubiquitous intermediates in flames burning a variety of fuels. This surprising observation will require combustion modelers to revise their models to account for the presence of these compounds.

131

Enol Intermediates Unexpectedly Found in Flames  

NLE Websites -- All DOE Office Websites (Extended Search)

Enol Intermediates Unexpectedly Found in Flames Print Enol Intermediates Unexpectedly Found in Flames Print For those studying flame chemistry and the properties of combustion intermediates by means of molecular beam mass spectrometry, the addition of tunable vacuum ultraviolet (VUV) from a synchrotron to photoionize the beam for mass spectrometry makes for a powerful technique capable of differentiating between isomers with the same molecular weight and composition. With the help of a unique experimental apparatus, an international team of American, Chinese, and German researchers has exploited this selectivity to identify chemical compounds known as enols as apparently ubiquitous intermediates in flames burning a variety of fuels. This surprising observation will require combustion modelers to revise their models to account for the presence of these compounds.

132

Enol Intermediates Unexpectedly Found in Flames  

NLE Websites -- All DOE Office Websites (Extended Search)

Enol Intermediates Unexpectedly Found in Flames Print Enol Intermediates Unexpectedly Found in Flames Print For those studying flame chemistry and the properties of combustion intermediates by means of molecular beam mass spectrometry, the addition of tunable vacuum ultraviolet (VUV) from a synchrotron to photoionize the beam for mass spectrometry makes for a powerful technique capable of differentiating between isomers with the same molecular weight and composition. With the help of a unique experimental apparatus, an international team of American, Chinese, and German researchers has exploited this selectivity to identify chemical compounds known as enols as apparently ubiquitous intermediates in flames burning a variety of fuels. This surprising observation will require combustion modelers to revise their models to account for the presence of these compounds.

133

NETL: Releases & Briefs - A Fascination with Flame  

NLE Websites -- All DOE Office Websites (Extended Search)

image velocimetry to understand why and how flames oscillate as their fuel-to-air consumption ratio is decreased. When new fuel-flexible gas turbines are designed run at these...

134

Light collection device for flame emission detectors  

DOE Patents (OSTI)

This report describes a light collection device for use in a flame emission detection system such as an on-line, real-time alkali concentration process stream monitor. The device comprises a sphere coated on its interior with a highly diffuse reflective paint which is positioned over a flame emission source and one or more fiber optic cables which transfer the light generated at the interior of the sphere to a detecting device. The diffuse scattering of the light emitted by the flame uniformly distributes the light in the sphere, and the collection efficiency of the device is greater than that obtainable in the prior art. The device of the present invention thus provides enhanced sensitivity and reduces the noise associated with flame emission detectors, and can achieve substantial improvements in alkali detection levels. 2 figs.

Woodruff, S.D.; Logan, R.G.; Pineault, R.L.

1989-04-14T23:59:59.000Z

135

Enol Intermediates Unexpectedly Found in Flames  

NLE Websites -- All DOE Office Websites (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...

136

Flame Spray Synthesis and Characterization of Nanocrystalline ...  

Science Conference Proceedings (OSTI)

The precursor solution was atomized by a jet nebulizer and allowed to pass through a co-flow diffusion burner in a reactor. A flame was generated by using LPG ...

137

Light collection device for flame emission detectors  

DOE Patents (OSTI)

A light collection device for use in a flame emission detection system such as an on-line, real-time alkali concentration process stream monitor is disclosed which comprises a sphere coated on its interior with a highly diffuse reflective paint which is positioned over a flame emission source, and one or more fiber optic cables which transfer the light generated at the interior of the sphere to a detecting device. The diffuse scattering of the light emitted by the flame uniformly distributes the light in the sphere, and the collection efficiency of the device is greater than that obtainable in the prior art. The device of the present invention thus provides enhanced sensitivity and reduces the noise associated with flame emission detectors, and can achieve substantial improvements in alkali detection levels.

Woodruff, Stephen D. (Morgantown, WV); Logan, Ronald G. (Morgantown, WV); Pineault, Richard L. (Morgantown, WV)

1990-01-01T23:59:59.000Z

138

Transient Supersonic Methane-Air Flames  

E-Print Network (OSTI)

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. The combustor was designed following well-known principles of jet engine combustors. A flame holder and spark plug combination was used to encourage turbulent mixing and ignition of reactant gases, and to anchor the transient flame. Combustion created a high temperature and pressure environment which propelled a flame through a choked de Laval nozzle. The nozzle accelerated the products of combustion to a Mach number of 1.6, creating an underexpanded transient flame which burned for approximately 25 milliseconds. Qualitative information of the flame was gathered by two optical systems. An intensified charge-coupled device (ICCD) was constructed from constitutive components to amplify and capture the chemiluminescence generated by the transient flame, as well as the spatial structure of the flame at specific phases. To gather temporal data of a single transient event as it unfolded, a z-type schlieren optical system was constructed for use with a high speed camera. The system resolves the data in 1 millisecond increments, sufficient for capturing the transient phenomenon. The transient system was modeled computationally in Cantera using the GRI-3.0 reaction mechanism. Experimental conditions were simulated within the zero- dimensional computation by explicit control of the reacting gas mass flow rates within the system. Results from the computational model were used to describe the ignition process. The major limitation of the zero-dimensional reactor model is homogeneity and lack of spatial mixing. In this work a Lagrangian tracking model was used to describe the flame behavior and properties as it travels within the zero-dimensional reactor towards the nozzle. Following this, the flow expansion through the de Laval nozzle was calculated using one-dimensional isentropic relations. The computed reactor model data was then contrasted to experimental results from the ICCD and high speed schlieren images to fully describe the events in the transient supersonic flame.

Richards, John L.

2012-05-01T23:59:59.000Z

139

Aromatics oxidation and soot formation in flames  

SciTech Connect

Work during this contract period has been concerned with the mechanisms through which aromatics are formed and destroyed in flames, and the processes responsible for soot formation. Recent progress has been primarily in two areas: experiments and modeling of the soot nucleation process in low pressure benzene flames and preparation for experiments on the destruction mechanisms of benzene. In addition, we have incorporated weak collision'' formalisms into a fall-off computer code.

Howard, J.B.

1989-01-01T23:59:59.000Z

140

Analyzing and Tracking Burning Structures in Lean Premixed Hydrogen Flames  

DOE Green Energy (OSTI)

This paper presents topology-based methods to robustly extract, analyze, and track features defined as subsets of isosurfaces. First, we demonstrate how features identified by thresholding isosurfaces can be defined in terms of the Morse complex. Second, we present a specialized hierarchy that encodes the feature segmentation independent of the threshold while still providing a flexible multi-resolution representation. Third, for a given parameter selection we create detailed tracking graphs representing the complete evolution of all features in a combustion simulation over several hundred time steps. Finally, we discuss a user interface that correlates the tracking information with interactive rendering of the segmented isosurfaces enabling an in-depth analysis of the temporal behavior. We demonstrate our approach by analyzing three numerical simulations of lean hydrogen flames subject to different levels of turbulence. Due to their unstable nature, lean flames burn in cells separated by locally extinguished regions. The number, area, and evolution over time of these cells provide important insights into the impact of turbulence on the combustion process. Utilizing the hierarchy we can perform an extensive parameter study without re-processing the data for each set of parameters. The resulting statistics enable scientist to select appropriate parameters and provide insight into the sensitivity of the results wrt. to the choice of parameters. Our method allows for the first time to quantitatively correlate the turbulence of the burning process with the distribution of burning regions, properly segmented and selected. In particular, our analysis shows that counter-intuitively stronger turbulence leads to larger cell structures, which burn more intensely than expected. This behavior suggests that flames could be stabilized under much leaner conditions than previously anticipated.

Bremer, Peer-Timo; Weber, Gunther; Pascucci, Valerio; Day, Marc; Bell, John

2009-06-01T23:59:59.000Z

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

High availability using virtualization  

E-Print Network (OSTI)

High availability has always been one of the main problems for a data center. Till now high availability was achieved by host per host redundancy, a highly expensive method in terms of hardware and human costs. A new approach to the problem can be offered by virtualization. Using virtualization, it is possible to achieve a redundancy system for all the services running on a data center. This new approach to high availability allows to share the running virtual machines over the servers up and running, by exploiting the features of the virtualization layer: start, stop and move virtual machines between physical hosts. The system (3RC) is based on a finite state machine with hysteresis, providing the possibility to restart each virtual machine over any physical host, or reinstall it from scratch. A complete infrastructure has been developed to install operating system and middleware in a few minutes. To virtualize the main servers of a data center, a new procedure has been developed to migrate physical to virtu...

Calzolari, Federico

2009-01-01T23:59:59.000Z

142

Suppression of a Nonpremixed Flame Stabilized by a ...  

Science Conference Proceedings (OSTI)

... Effects of Clutter on Performance of Fire Suppression Agents in Aircraft DIY Bays and Engine Nacelles, Report prepared for Booz, Allen and ...

2011-07-05T23:59:59.000Z

143

Designing and embedding reliable virtual infrastructures  

Science Conference Proceedings (OSTI)

In a virtualized infrastructure where physical resources are shared, a single physical server failure will terminate several virtual servers and crippling the virtual infrastructures which contained those virtual servers. In the worst case, more failures ... Keywords: infrastructure virtualization

Wai-Leong Yeow; Cédric Westphal; Ula? Kozat

2010-09-01T23:59:59.000Z

144

On the dynamics of flame edges in diffusion-flame/vortex interactions  

Science Conference Proceedings (OSTI)

We analyze the local flame extinction and reignition of a counterflow diffusion flame perturbed by a laminar vortex ring. Local flame extinction leads to the appearance of flame edges separating the burning and extinguished regions of the distorted mixing layer. The dynamics of these edges is modeled based on previous numerical results, with heat release effects fully taken into account, which provide the propagation velocity of triple and edge flames in terms of the upstream unperturbed value of the scalar dissipation. The temporal evolution of the mixing layer is determined using the classical mixture fraction approach, with both unsteady and curvature effects taken into account. Although variable density effects play an important role in exothermic reacting mixing layers, in this paper the description of the mixing layer is carried out using the constant density approximation, leading to a simplified analytical description of the flow field. The mathematical model reveals the relevant nondimensional parameters governing diffusion-flame/vortex interactions and provides the parameter range for the more relevant regime of local flame extinction followed by reignition via flame edges. Despite the simplicity of the model, the results show very good agreement with previously published experimental results. (author)

Hermanns, Miguel; Linan, Amable [Departamento de Motopropulsion y Termofluidodinamica, Universidad Politecnica de Madrid, Pza. Cardenal Cisneros 3, 28040 Madrid (Spain); Vera, Marcos [Area de Mecanica de Fluidos, Universidad Carlos III de Madrid, 28911 Leganes (Spain)

2007-04-15T23:59:59.000Z

145

Flames in Type Ia Supernova: Deflagration-Detonation Transition in the Oxygen Burning Flame  

E-Print Network (OSTI)

Flames in Type Ia Supernova: Deflagration-Detonation Transition in the Oxygen Burning Flame S. E structure which, de- pending on density, may involve separate regions of carbon, oxygen and silicon burning, all propagating in a self-similar, subsonic front. The separation between these three burning regions

146

Numerical Issues of Monte Carlo PDF for Large Eddy Simulations of Turbulent Flames  

E-Print Network (OSTI)

piloted methane jet flame (Sandia Flame D),” Presented atof a pure mixing jet and Sandia Flame D using a steady-stateon pure mixing jet and Sandia flame D with a steady-

Bisetti, Fabrizio; Chen, J Y

2005-01-01T23:59:59.000Z

147

ARM - Measurement - Virtual temperature  

NLE Websites -- All DOE Office Websites (Extended Search)

govMeasurementsVirtual temperature govMeasurementsVirtual temperature ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Measurement : Virtual temperature The virtual temperature Tv = T(1 + rv/{epsilon}), where rv is the mixing ratio, and {epsilon} is the ratio of the gas constants of air and water vapor ( 0.622). Categories Atmospheric State Instruments The above measurement is considered scientifically relevant for the following instruments. Refer to the datastream (netcdf) file headers of each instrument for a list of all available measurements, including those recorded for diagnostic or quality assurance purposes. ARM Instruments CO2FLX : Carbon Dioxide Flux Measurement Systems MWRP : Microwave Radiometer Profiler RWP : Radar Wind Profiler

148

In the Virtual Extension  

Science Conference Proceedings (OSTI)

To ensure the timely publication of articles, Communications created the Virtual Extension (VE) to expand the page limitations of the print edition by bringing readers the same high-quality articles in an online-only format. VE articles undergo ...

CACM Staff

2011-06-01T23:59:59.000Z

149

Virtual Doppler Lidar Instrument  

Science Conference Proceedings (OSTI)

Doppler lidars measure the range-resolved line-of-sight wind component by extracting the Doppler shift of radiation backscattered from atmospheric aerosols and molecules. A virtual instrument was developed to simulate wind measurements by flying ...

Ines Leike; Jürgen Streicher; Christian Werner; Viktor Banakh; Igor Smalikho; Werner Wergen; Alexander Cress

2001-09-01T23:59:59.000Z

150

The Lure of the Virtual  

Science Conference Proceedings (OSTI)

Although organizational scholars have begun to study virtual work, they have yet to fully grapple with its diversity. We draw on semiotics to distinguish among three types of virtual work (virtual teams, remote control, and simulations) based on what ... Keywords: digitization, organizing for innovation, product design, representation, semiotics, simulation, technological change, virtual work

Diane E. Bailey; Paul M. Leonardi; Stephen R. Barley

2012-09-01T23:59:59.000Z

151

Laminar flame speeds of moist syngas mixtures  

SciTech Connect

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

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

2011-02-15T23:59:59.000Z

152

Ultraviolet imaging of hydrogen flames  

DOE Green Energy (OSTI)

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.

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

1988-01-01T23:59:59.000Z

153

Distributed Flames in Type Ia Supernovae  

E-Print Network (OSTI)

In the distributed burning regime, turbulence disrupts the internal structure of the flame, and so the idea of laminar burning propagated by conduction is no longer valid. The nature of the burning depends on the turbulent Damkohler number (Da), which steadily declines from much greater than one to less that one as the density decreases to a few 10^6 g/cc. Scaling arguments predict that the turbulent flame speed s, normalized by the turbulent intensity u, follows s/u=Da^1/2 for Da1, and that localized excursions to as much as five times u can occur. The lambda-flame speed and width can be predicted based on the turbulence in the star and the turbulent nuclear burning time scale of the fuel. We propose a practical method for measuring these based on the scaling relations and small-scale computationally-inexpensive simulations. This suggests that a simple turbulent flame model can be easily constructed suitable for large-scale distributed supernovae flames.

Aspden, A J; Woosley, S E; 10.1088/0004-637X/710/2/1654

2011-01-01T23:59:59.000Z

154

Chaotic radiation/turbulence interactions in flames  

SciTech Connect

In this paper, the authors present a review of their recent efforts to model chaotic radiation-turbulence interactions in flames. The main focus is to characterize soot volume fraction fluctuations in turbulent diffusion flames, as they strongly contribute to these interaction. The approach is based on the hypothesis that the fluctuations of properties in turbulent flames are deterministic in nature, rather than random. The authors first discuss the theoretical details and then they briefly outline the experiments conducted to measure the scattered light signals from fluctuating soot particles along the axis of an ethylene-air diffusion flame. They compare the power spectra and time series obtained from experiments against the ad-hoc and rigorous models derived using a series of logistic maps. These logistic maps can be used in simulation of the fluctuations in these type of flames, without extensive computational effort or sacrifice of physical detail. Availability of accurate models of these kinds allows investigation of radiation-turbulence interactions at a more fundamental level than it was previously possible.

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

1998-11-01T23:59:59.000Z

155

Flame-vortex interaction and mixing behaviors of turbulent non-premixed jet flames under acoustic forcing  

SciTech Connect

This study examines the effect of acoustic excitation using forced coaxial air on the flame characteristics of turbulent hydrogen non-premixed flames. A resonance frequency was selected to acoustically excite the coaxial air jet due to its ability to effectively amplify the acoustic amplitude and reduce flame length and NO{sub x} emissions. Acoustic excitation causes the flame length to decrease by 15% and consequently, a 25% reduction in EINO{sub x} is achieved, compared to coaxial air flames without acoustic excitation at the same coaxial air to fuel velocity ratio. Moreover, acoustic excitation induces periodical fluctuation of the coaxial air velocity, thus resulting in slight fluctuation of the fuel velocity. From phase-lock PIV and OH PLIF measurement, the local flow properties at the flame surface were investigated under acoustic forcing. During flame-vortex interaction in the near field region, the entrainment velocity and the flame surface area increased locally near the vortex. This increase in flame surface area and entrainment velocity is believed to be a crucial factor in reducing flame length and NO{sub x} emission in coaxial jet flames with acoustic excitation. Local flame extinction occurred frequently when subjected to an excessive strain rate, indicating that intense mass transfer of fuel and air occurs radially inward at the flame surface. (author)

Kim, Munki; Choi, Youngil; Oh, Jeongseog; Yoon, Youngbin [School of Mechanical and Aerospace Engineering, Seoul National University, Seoul (Korea)

2009-12-15T23:59:59.000Z

156

Paper # A02 Topic: Laminar Flames US Combustion Meeting  

E-Print Network (OSTI)

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

Seitzman, Jerry M.

157

Molecular-Beam Mass-Spectrometric Analyses of Hydrocarbon Flames.  

E-Print Network (OSTI)

??Laminar flat flame combustion has been studied with molecular-beam mass-spectrometry (MBMS) for a fuel-rich cyclohexane (? = 2.003) flame, a fuel-lean toluene (? = 0.895),… (more)

Gon, Saugata

2008-01-01T23:59:59.000Z

158

Flame Temperature Field Measurement Using Improved Generalized Cross Validation Method  

Science Conference Proceedings (OSTI)

The image quality is a crucial factor for calculating flame temperature field based on the color CCD method. However, much unknown noise in flame images would prevent from obtaining the temperature with accuracy. To eliminate noise, the wavelet denoising ...

Yinghui Zhou; Dezhong Zheng

2007-10-01T23:59:59.000Z

159

Pentan isomers compound flame front structure  

DOE Green Energy (OSTI)

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.

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

160

Analyzing and Tracking Burning Structures in Lean Premixed Hydrogen Flames  

E-Print Network (OSTI)

Analyzing and Tracking Burning Structures in Lean Premixed Hydrogen Flames P.-T. Bremer1, G. Weber2 flames subject to different levels of tur- bulence. Due to their unstable nature, lean flames burn to quantitatively correlate the turbulence of the burning process with the distribution of burning regions, properly

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

An Inverted Co-Flow Diffusion Flame for Producing Soot  

E-Print Network (OSTI)

R. A. Dobbins, Combustion & Flame. v 92 n 3, 320-333 (1993).and W. Lee, Combust. and Flame, 109, 266- 6. D. X. Du, H.C. K. Law, Combust. and Flame, 113, 264-270 (1998). 7. B. R.

Stipe, Christopher B.; Higgins, Brian S.; Lucas, Donald; Koshland, Catherine P.; Sawyer, Robert F.

2005-01-01T23:59:59.000Z

162

FLAME DENITRATION AND REDUCTION OF URANIUM NITRATE TO URANIUM DIOXIDE  

DOE Patents (OSTI)

A process is given for converting uranyl nitrate solution to uranium dioxide. The process comprises spraying fine droplets of aqueous uranyl nitrate solution into a hightemperature hydrocarbon flame, said flame being deficient in oxygen approximately 30%, retaining the feed in the flame for a sufficient length of time to reduce the nitrate to the dioxide, and recovering uranium dioxide. (AEC)

Hedley, W.H.; Roehrs, R.J.; Henderson, C.M.

1962-06-26T23:59:59.000Z

163

High efficiency virtual impactor  

DOE Patents (OSTI)

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.

Loo, B.W.

1980-03-27T23:59:59.000Z

164

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

E-Print Network (OSTI)

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

Zare, Richard N.

165

Improving virtual appliance management through virtual layered file systems  

Science Conference Proceedings (OSTI)

Managing many computers is difficult. Recent virtualization trends exacerbate this problem by making it easy to create and deploy multiple virtual appliances per physical machine, each of which can be configured with different applications and utilities. ...

Shaya Potter; Jason Nieh

2011-12-01T23:59:59.000Z

166

Detailed modeling and laser-induced fluorescence imaging of nitric oxide in a NH(i)-seeded non-premixed methane/air flame  

E-Print Network (OSTI)

an axisymmetric laminar diffusion flame. Proc. Comb. Inst. ,laminar diffusion flames. Combust. Sci. Tech. , [25] N .premixed ethylene/air flames. Combust. Flame, 127:2004-2022,

2001-01-01T23:59:59.000Z

167

Virtual People: Capturing Human Models to Populate Virtual Worlds  

Science Conference Proceedings (OSTI)

In this paper a new technique is introduced for automatically building recognisable moving 3D models of individual people Realistic modelling of people is essential for advanced multimedia, augmented reality and immersive virtual reality. Current systems ... Keywords: Avatar, Virtual Human, Whole-body Modelling, Humanoid Animation, Virtual Reality, VRML, Vision Techniques, 3D Reconstruction

Adrian Hilton; Daniel Beresford; Thomas Gentils; Raymond Smith; Wei Sun

1999-05-01T23:59:59.000Z

168

Multimodal astronaut virtual training prototype  

Science Conference Proceedings (OSTI)

A few dedicated training simulator applications exist that mix realistic interaction devices-like real cockpits in flight simulators-with virtual environment (VE) components. Dedicated virtual reality (VR) systems have been utilized also in astronaut ...

Jukka Rönkkö; Jussi Markkanen; Raimo Launonen; Marinella Ferrino; Enrico Gaia; Valter Basso; Harshada Patel; Mirabelle D'Cruz; Seppo Laukkanen

2006-03-01T23:59:59.000Z

169

The effects of gravity on wrinkled laminar flames  

Science Conference Proceedings (OSTI)

Laminar and turbulent conical Bunsen type flames were used. The study compares results from normal gravity with the burner in an up-right orientation (+g), the burner inverted (-g), and in microgravity ({mu}g) by using the NASA Lewis drop tower facility. The primary diagnostic is a laser schlieren system and some LDA measurements were taken for the +g condition to measure the flow field. The +g laminar flame experiences a large amount of instabilities and results in an unsteady flame tip; cause is torroidal vortex rolling up between products and stagnate surrounding air. Comparison between LDA measurements in reactants and schlieren images shows that velocity fluctuation are induced at the same frequency as the roll up vortices are formed. This pumping of the reactant stream by the product/air interface instability in the +g case is also observed in the turbulent flames. In the -g arrangement the product/air interface is stable so there is no large pumping of the flame tip. At low flow rates the -g flames have flattened tips, but at higher flow rates they become conical in shape. When both flames. appear conical, the -g flames are longer for the same flow rate. In {mu}g the larger instabilities in the flame no longer exist as the product/air interface is believed to become stable. The laminar flames in {mu}g still show small instabilities over the entire flame.

Kostiuk, L.W.; Zhou, L.; Cheng, R.K.

1992-09-01T23:59:59.000Z

170

The effects of gravity on wrinkled laminar flames  

Science Conference Proceedings (OSTI)

Laminar and turbulent conical Bunsen type flames were used. The study compares results from normal gravity with the burner in an up-right orientation (+g), the burner inverted (-g), and in microgravity ([mu]g) by using the NASA Lewis drop tower facility. The primary diagnostic is a laser schlieren system and some LDA measurements were taken for the +g condition to measure the flow field. The +g laminar flame experiences a large amount of instabilities and results in an unsteady flame tip; cause is torroidal vortex rolling up between products and stagnate surrounding air. Comparison between LDA measurements in reactants and schlieren images shows that velocity fluctuation are induced at the same frequency as the roll up vortices are formed. This pumping of the reactant stream by the product/air interface instability in the +g case is also observed in the turbulent flames. In the -g arrangement the product/air interface is stable so there is no large pumping of the flame tip. At low flow rates the -g flames have flattened tips, but at higher flow rates they become conical in shape. When both flames. appear conical, the -g flames are longer for the same flow rate. In [mu]g the larger instabilities in the flame no longer exist as the product/air interface is believed to become stable. The laminar flames in [mu]g still show small instabilities over the entire flame.

Kostiuk, L.W.; Zhou, L.; Cheng, R.K.

1992-09-01T23:59:59.000Z

171

Increased Cytotoxicity of Oxidized Flame Soot  

NLE Websites -- All DOE Office Websites (Extended Search)

Increased Cytotoxicity of Oxidized Flame Soot Increased Cytotoxicity of Oxidized Flame Soot Title Increased Cytotoxicity of Oxidized Flame Soot Publication Type Journal Article Year of Publication 2012 Authors Holder, Amara L., Brietta J. Carter, Regine Goth-Goldstein, Donald Lucas, and Catherine P. Koshland Journal Atmospheric Pollution Research Volume 3 Start Page 25 Issue 1 Pagination 25-31 Date Published 01/2012 Keywords health effects, ozone, soot, toxicity Abstract Combustion-generated particles released into the atmosphere undergo reactions with oxidants, which can change the particles' physiochemical characteristics. In this work, we compare the physical and chemical properties and cellular response of particles fresh from a flame with those oxidized by ozone and nitrogen dioxide. The reaction with ozone and nitrogen dioxide does not significantly modify the physical characteristics of the particles (primary particle size, fractal dimension, and surface area). However, oxidation affects the chemical characteristics of the particles, creating more oxygen and nitrogen containing functional groups, and increases their hydrophilicity. In addition, oxidized soot generates more reactive oxygen species, as measured by the dithiothreitol (DTT) assay. Furthermore, oxidized soot is 1.5-2 times more toxic than soot that was not reacted with ozone, but the inflammatory response, measured by interleukin-8 (IL-8) secretion, is unchanged. These results imply that combustion-generated particles released into the atmosphere will have an increased toxicity on or after high ozone days.

172

Virtual Environments for Health Care  

Science Conference Proceedings (OSTI)

... condition and state of consciousness" (Kahaner, 1994 ... reality] stimulations to the human" (Nakajima, Nomura ... of virtual reality simulations to humans. ...

1996-02-14T23:59:59.000Z

173

Spark Ignited Turbulent Flame Kernel Growth  

DOE Green Energy (OSTI)

An experimental study of the effects of spark power and of incomplete fuel-air mixing on spark-ignited flame kernel growth was conducted in turbulent propane-air mixtures at 1 atm, 300K conditions. The results showed that increased spark power resulted in an increased growth rate, where the effect of short duration breakdown sparks was found to persist for times of the order of milliseconds. The effectiveness of increased spark power was found to be less at high turbulence and high dilution conditions. Increased spark power had a greater effect on the 0-5 mm burn time than on the 5-13 mm burn time, in part because of the effect of breakdown energy on the initial size of the flame kernel. And finally, when spark power was increased by shortening the spark duration while keeping the effective energy the same there was a significant increase in the misfire rate, however when the spark power was further increased by increasing the breakdown energy the misfire rate dropped to zero. The results also showed that fluctuations in local mixture strength due to incomplete fuel-air mixing cause the flame kernel surface to become wrinkled and distorted; and that the amount of wrinkling increases as the degree of incomplete fuel-air mixing increases. Incomplete fuel-air mixing was also found to result in a significant increase in cyclic variations in the flame kernel growth. The average flame kernel growth rates for the premixed and the incompletely mixed cases were found to be within the experimental uncertainty except for the 33%-RMS-fluctuation case where the growth rate was significantly lower. The premixed and 6%-RMS-fluctuation cases had a 0% misfire rate. The misfire rates were 1% and 2% for the 13%-RMS-fluctuation and 24%-RMS-fluctuation cases, respectively; however, it drastically increased to 23% in the 33%-RMS-fluctuation case.

Santavicca, D.A.

1995-06-01T23:59:59.000Z

174

Flame quality monitor system for fixed firing rate oil burners  

DOE Patents (OSTI)

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.

Butcher, T.A.; Cerniglia, P.

1990-10-23T23:59:59.000Z

175

Flame quality monitor system for fixed firing rate oil burners  

DOE Patents (OSTI)

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.

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

1992-01-01T23:59:59.000Z

176

Environmentally Benign Flame Retardant Nanocoatings for Fabric  

E-Print Network (OSTI)

A variety of materials were used to fabricate nanocoatings using layer-by-layer (LbL) assembly to reduce the flammability of cotton fabric. The most effective brominated flame retardants have raised concerns related to their toxicity and environmental impact, which has created a need for alternative flame retardant chemistries and approaches. Polymer nanocomposites typically exhibit reduced mass loss and heat release rates, along with anti-dripping behavior, all of which are believed to be due to the formation of a barrier surface layer. Despite these benefits, the viscosity and modulus of the final polymeric material is often altered, making industrial processing difficult. These challenges inspired the use of LbL assembly to create densely layered 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 mixtures. Both films can be grown linearly as a function of layers deposited, and they contained at least 70 wt percent of clay. When applying these films to cotton fabric, the individual fibers are uniformly coated and the fabric has significant char left after burning. MMT-coated fabric exhibits reduced total heat release, suggesting a protective ceramic surface layer is created. Small molecule, POSS-based LbL thin films were also successfully deposited on cotton fabric. With less than 8 wt percent added to the total fabric weight, more than 12 wt percent char remained after microscale combustion calorimetry. Furthermore, afterglow time was reduced and the fabric weave structure and shape of the individual fibers were highly preserved following vertical flame testing. A silica-like sheath was formed after burning that protected the fibers. Finally, the first intumescent LbL assembly was deposited on cotton fabric. SEM images show significant bubble formation on fibers, coated with a 0.5 wt percent PAAm/1 wt percent PSP coating after burning. In several instances, a direct flame on the fabric was extinguished. The peak HRR and THR of coated fabric has 30 percent and 65 percent reduction, respectively, compared to the uncoated control fabric. These anti-flammable nanocoatings provide a relatively environmentally-friendly alternative for protecting fabrics, such as cotton, and lay the groundwork for rendering many other complex substrates (e.g., foam) flame-retardant without altering their processing and desirable mechanical behavior.

Li, Yu-Chin

2011-05-01T23:59:59.000Z

177

Virtual Environment and  

E-Print Network (OSTI)

The levels of immersion and presence felt by users in a Virtual Environment (VE) are very important factors that dictate the quality of the Virtual Reality (VR) experience. Sensori-motor systems, both hardware and software, are the components of a VR system that contribute to generate the VEs and to create the feeling of being there. This paper reviews the different visualization hardware/software components that are at the heart of a VR system and provides means for assessing their performance in the context of various applications. Because of its historical and functional importance in the field of VR, visualization hardware is reviewed first (HMDs, VRDs, stereo glasses, CRT, LCD monitors and Plasma displays...). Then, a list of the most important insights, which should be addressed when designing and assembling a VR system, are discussed. Finally, visualization software is covered in the context of the available hardware components.

Sensori-Motor Activities Visualization; M. Mokhtari; F. Lemieux; F. Bernier; D. Ouellet; R. Drouin; D. Laurendeau; A. Branzan-albu

2004-01-01T23:59:59.000Z

178

Strained flamelets for turbulent premixed flames, I: Formulation and planar flame results  

SciTech Connect

A strained flamelet model is proposed for turbulent premixed flames using scalar dissipation rate as a parameter. The scalar dissipation rate of reaction progress variable is a suitable quantity to describe the flamelet structure since it is governed by convection-diffusion-reaction balance and it is defined at every location in the flamelets, which are represented by laminar flames in reactant-to-product opposed flow configuration. The mean reaction rate is obtained by using the flamelets reaction rate and the joint pdf of the progress variable and its dissipation rate. The marginal pdf of the progress variable is presumed to be {beta}-pdf and the pdf of the conditional dissipation rate is taken to be log-normal. The conditional mean dissipation rate is obtained from modelled mean dissipation rate. This reaction rate closure is assessed using RANS calculations of statistically planar flames in the corrugated flamelets and thin reaction zones regimes. The flame speeds calculated using this closure are close to the experimental data of Abdel-Gayed et al. (1987) for flames in both the regimes. Comparisons with other reaction rate closures showed the benefits of the strained flamelets approach. (author)

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

2010-05-15T23:59:59.000Z

179

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

DOE Data Explorer (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.

None

180

Virtual Human Problem Solving Environments  

SciTech Connect

Abstract. Interest in complex integrated digital or virtual human modeling has seen a significant increase over the last decade. Coincident with that increased interest, Oak Ridge National Laboratory (ORNL) initiated the development of a human simulation tool, the Virtual Human. The Virtual Human includes a problem-solving environment (PSE) for implementing the integration of physiological models in different programming languages and connecting physiological function to anatomy. The Virtual Human PSE (VHPSE) provides the computational framework with which to develop the concept of a "Virtual Human." Supporting the framework is a data definition for modeling parameters, PhysioML, a Virtual Human Database (VHDB), and a Web-based graphical user interface (GUI) developed using Java. Following description of the VHPSE, we discuss four example implementations of models within the framework. Further expansion of a human modeling environment was carried out in the Defense Advanced Research Projects Agency Virtual Soldier Project. SCIRun served as the Virtual Soldier problem solving environment (VSPSE). We review and compare specific developments in these projects that have significant potential for the future of Virtual Human modeling and simulation. We conclude with an evaluation of areas of future work that will provide important extensions to the VHPSE and VSPSE and make possible a fully-integrated environment for human anatomical and physiological modeling: the Virtual Human.

Ward, Richard C [ORNL; Pouchard, Line Catherine [ORNL; Munro, Nancy B [ORNL; Fischer, Sarah Kathleen [ORNL

2008-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

The Soret Effect in Naturally Propagating, Premixed, Lean, Hydrogen-Air Flames  

E-Print Network (OSTI)

H. Markstein (Ed. ), Nonsteady Flame Propagation, PergamonHassan, G. M. Faeth, Combust. Flame 109 (1997) 1–24. [6] Y.P. Middha, H. Wang, Combus. Flame [7] F. N. Egolfopoulos, C.

Grcar, Joseph F

2008-01-01T23:59:59.000Z

182

STUDIES OF WALL FLAME QUENCHING AND HYDROCARBON EMISSIONS IN A MODEL SPARK IGNITION ENGINE  

E-Print Network (OSTI)

spark ignition . Particle velocity at a flame front Profileof apparent flame front approaching a position at a side warolled-up votex and CH4-air flame; equivalence ratio 0.6,

Ishikawa, Nobuhiko

2011-01-01T23:59:59.000Z

183

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

E-Print Network (OSTI)

along the centerline of a flame from the 7.5 mm ID nozzle,Oxide Nanoparticles in a Diffusion Flame Bing Guo and Ian M.in a hydrogen diffusion flame seeded with Cr(CO) 6 vapor.

Guo, B; Kennedy, Ian M

2004-01-01T23:59:59.000Z

184

MODELLING OF BURNING AND EXTINCTION CHARACTERISTICS OF A POLYMER DIFFUSION FLAME AND COMPARISON WITH EXPERIMENT  

E-Print Network (OSTI)

and Seshadri, K. : Combustion and Flame, 26, 363, 1976. ActaD.P. and Prahl, J.M. : and Flame 33, 55, 1978. Burke, S.P.OF A POLYMER DIFFUSION FLAME AND COMPARISON WITH EXPERIMENT

Pitz, W.J.

2012-01-01T23:59:59.000Z

185

Dynamics of the flame flowfields in a low-swirl burner  

E-Print Network (OSTI)

Cheng, R.K. , Combustion and Flame 127:2066 (2001). Chan,4 /air premixed turbulent flames at ? = 0.8 and U o = 5, 7.5Cheng, R.K. , Combustion and Flame 100:485 (1995). Cheng,

Johnson, Matthew R.

2003-01-01T23:59:59.000Z

186

Flow-Assisted Flame Propagation Through a Porous Combustible in Microgravity  

E-Print Network (OSTI)

P.J. Pagni and T.G. Peterson, “Flame Spread Through PorousT. Niioka, ”Flow-Assisted Flame Propagation Through a PorousMarch 2002 Flow-Assisted Flame Propagation Through a Porous

Bar-Ilan, Amnon; Rich, David B; Rein, Guillermo; Fernandez-Pello, Carlos; Hanai, H.; Niioka, T.

2002-01-01T23:59:59.000Z

187

Numerical simulation of a laboratory-scale turbulent V-flame  

E-Print Network (OSTI)

and P. S. Wyckoff. Combust. Flame, [13] H. N. Najm and P.S. Wyckoff. Combust. Flame, 110(1–2):92–112, 1997. [14] R.and J. M. Donbar. Combust. Flame, 2005. in press. [7] M.

2005-01-01T23:59:59.000Z

188

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

E-Print Network (OSTI)

of counterflow diffusion flames above condensed fuels.IN AN OPPOSED FLOW DIFFUSION FLAME* W.K. Chin R.F. Sawyeropposed flow diffusion flame burner. An earlier experimental

Chin, W.K.

2011-01-01T23:59:59.000Z

189

Durable and Non-Toxic Topical Flame Retardants for Cotton and Cotton Blends.  

E-Print Network (OSTI)

??Flame retardant chemicals were used as topical finishes on cotton and cotton blended fabric. Comparison of flame resistance and durability of non-bromine/non-antimony flame retardants were… (more)

Mathews, Marc Christopher

2008-01-01T23:59:59.000Z

190

Scaling and efficiency of PRISM in adaptive simulations of turbulent premixed flames  

E-Print Network (OSTI)

one-dimensional premixed flames," Sandia National Labora-U. and Pope, S. B. , Combust. Flame, 88:239-264 (1992). [7]B. and Pope, S. B. , Combust. Flame, 112:85-112 (1998). [13

Tonse, Shaheen R.

2011-01-01T23:59:59.000Z

191

LES of Sandia Flame D with Eulerian PDF and Finite-Rate Chemistry  

E-Print Network (OSTI)

mixing models. Com- bust. Flame 136, 208–216. Subramaniam,Ald´ n, M. , Kaminski, C. , e 2000. Flame front tracking andspanning trees. Combust. Flame 115, 487–514. Tang, Q. , Xu,

Bisetti, Fabrizio; Chen, J Y

2005-01-01T23:59:59.000Z

192

Numerical Issues of Monte Carlo PDF for Large Eddy Simulations of Turbulent Flames  

E-Print Network (OSTI)

Carlo PDF Methods for Turbulent Diffusion Flames,” Combust.Flame 124:519-534 (2001). Muradoglu, M. , Jenny, P. Pope,Methane-Air Nonpremixed Jet Flames,” Combustion Science and

Bisetti, Fabrizio; Chen, J Y

2005-01-01T23:59:59.000Z

193

Flame Doctor for Cyclone Boilers: Beta Demonstration Program  

Science Conference Proceedings (OSTI)

This report describes the results of the beta demonstration of the Flame Doctor system as it is applied to cyclone boilers.

2012-07-10T23:59:59.000Z

194

Flashback, Blow out, Emissions and Turbulent Displacement Flame...  

NLE Websites -- All DOE Office Websites (Extended Search)

driving physics relating turbulent flame speeds to flashback at conditions relevant to gas turbine engines. Testing was conducted in an optically accessible single nozzle...

195

Influence of Different Parameters on Theoretical Flame Temperature ...  

Science Conference Proceedings (OSTI)

One of the main parameters to measure the thermal state in Corex melter gasifier is the theoretical flame temperature (TFT) before tuyere, which is important to ...

196

Boundary Layer Flame Spread over PMMA within the Initial ...  

Science Conference Proceedings (OSTI)

... INTRODUCTION Boundary layer-type flames are prevalent in wall fires, ceiling fires, and wind-driven fires on flat surfaces such as floors and roofs. ...

2011-11-03T23:59:59.000Z

197

Session Overview: Flame Synthesis Hai Wang, Session Chair Dept...  

NLE Websites -- All DOE Office Websites (Extended Search)

of gas-phase chemistry, heterogeneous reaction kinetics and materials thermodynamics and kinetics. A successful flame synthesis route to a particular material is often...

198

Catalytic inhibition of laminar flames by transition metal ...  

Science Conference Proceedings (OSTI)

... measurements of OH concentration reduction in low-pressure counterflow diffusion flames inhibited by Fe(CO)5, using laser-induced fluorescence ...

2008-10-16T23:59:59.000Z

199

Influence of the Pulverized Coal Ash on Theoretical Flame ...  

Science Conference Proceedings (OSTI)

Moreover, the modified formula for calculating of theoretical flame temperature before tuyere is established. The effect of the ratio of reduced SiO2 in raceway ...

200

Flame Synthesized Metal Oxide Nanowires as Effective Photoanodes  

NLE Websites -- All DOE Office Websites (Extended Search)

Stanford, CA 94305, USA I will discuss an atmospheric, cost-effective and scalable flame synthesis method for the growth and doping of metal oxide nanowires and these...

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Development and testing of flame retardant additives and polymers.  

E-Print Network (OSTI)

??The first chapter examines the non-halogenated flame retardant additives. The synthesis and blending of these various boron compounds are discussed and the blending of these… (more)

Jurs, Joshua Lewis

2004-01-01T23:59:59.000Z

202

Flame-capturing technique. 1: Adaptation to gas expansion  

E-Print Network (OSTI)

Various flame tracking techniques are often used in hydrodynamic simulations. Their use is indispensable when resolving actual scale of the flame is impossible. We show that parameters defining "artificial flame" propagation found from model systems may yield flame velocities several times distinct from the required ones, due to matter expansion being ignored in the models. Integral effect of material expansion due to burning is incorporated into flame capturing technique (FCT) [Khokhlov(1995)]. Interpolation formula is proposed for the parameters governing flame propagation yielding 0.2% accurate speed and width for any expansion (and at least 0.01% accurate for expansions typical in type Ia supernova explosions.) Several models with simple burning rates are studied with gas expansion included. Plausible performance of the technique in simulations is discussed. Its modification ensuring finite flame width is found. Implementation suggestions are summarized, main criterion being the scheme performance being insensitive to expansion parameter (thus absence of systematic errors when the burning progresses from inner to outer layers); in this direction promising realizations are found, leading to flame structure not changing while flame evolves through the whole range of densities in the white dwarf.

Andrey V. Zhiglo

2005-11-12T23:59:59.000Z

203

High Frequency Acoustic Wave Scattering From Turbulent Premixed Flames .  

E-Print Network (OSTI)

??This thesis describes an experimental investigation of high frequency acoustic wave scattering from turbulent premixed flames. The objective of this work was to characterize the… (more)

Narra, Venkateswarlu

2008-01-01T23:59:59.000Z

204

Particle Size Effects on the Morphology and Bioactivity of Flame ...  

Science Conference Proceedings (OSTI)

Flame spraying was used to manufacture coatings with different levels of porosity by altering both the deposition conditions and the feedstock particle size ...

205

Analysis of the Wave Scattering From Turbulent Premixed Flame .  

E-Print Network (OSTI)

??A theoretical investigation of acoustic wave interactions with turbulent premixed flames was performed. Such interactions affect the characteristic unsteadiness of combustion processes, e.g., combustion instabilities.… (more)

Cho, Ju Hyeong

2006-01-01T23:59:59.000Z

206

Mechanism of Sulfur-containing Aryl Polyphosphonate as Flame ...  

Science Conference Proceedings (OSTI)

Presentation Title, Mechanism of Sulfur-containing Aryl Polyphosphonate as Flame Retardant for PET. Author(s), Deng Yi. On-Site Speaker (Planned), Deng Yi.

207

FIELD TEST OF THE FLAME QUALITY INDICATOR  

Science Conference Proceedings (OSTI)

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.

Andrew M. Rudin; Thomas Butcher; Henry Troost

2003-02-04T23:59:59.000Z

208

Virtual Rapid Chloride Permeability Test  

Science Conference Proceedings (OSTI)

... final temperature can be manually copied to the final temperature in the test conditions box ... Type of software: Virtual testing of chloride permeability. ...

2013-06-11T23:59:59.000Z

209

Development of Virtual Power Plants  

NLE Websites -- All DOE Office Websites (Extended Search)

Virtual Power Plants We are working in the emerging intersection between information, computation, and complexity Applications * Design * Environmental modeling * Controls with...

210

Virtual Frog Dissection Kit Tutorial  

NLE Websites -- All DOE Office Websites (Extended Search)

and function Item 8: Using a different language Item 10: Resetting to defaults Berkeley Lab | ACS | Notice to Users | Whole Frog Project | Virtual Frog Page last modified: 0126...

211

Applying Virtual Environments to Manufacturing  

Science Conference Proceedings (OSTI)

... Users bring their architectural plans to the Matsushita store ... extension to the original virtual wind tunnel, NASA ... tracker with a graphics generator or a ...

1995-11-14T23:59:59.000Z

212

Modeling of flame spread over thin fuels on downward configuration in the presence of forced convection.  

E-Print Network (OSTI)

??The purpose of this thesis is to simulate the downward flame spread over thin fuel (Cellulose and Polymethylmethacrylate) in a natural convection environment. Flame spread… (more)

Patel, Gaurav Rameshbhai

2013-01-01T23:59:59.000Z

213

Virtual collaboration in oil and gas organizations  

Science Conference Proceedings (OSTI)

This paper covers some general observations regarding the relations between remote operation concepts and virtual organizations. In this paper we will show that remote operation concepts among other things involve developing systems supporting communication ... Keywords: line of operation, lines of operation, remote operation, virtual collaboration, virtual communication, virtual organizations, virtual room

Kenneth Gulbrandsøy; Vidar Hepsø; Amund Skavhaug

2002-12-01T23:59:59.000Z

214

Cultural learning in virtual heritage: an overview  

Science Conference Proceedings (OSTI)

The aim of this paper is to present the overview of cultural learning in virtual heritage. In the past, works done on virtual heritage were mostly focused on replicating and visualizing heritage objects for presentation using virtual reality. However, ... Keywords: cultural learning, virtual environment, virtual heritage, visual informatics

Nazrita Ibrahim; Nazlena Mohamad Ali; Noor Faezah Mohd Yatim

2011-11-01T23:59:59.000Z

215

E-commerce transactions in a virtual environment: virtual transactions  

Science Conference Proceedings (OSTI)

E-commerce is a fundamental method of doing business, such that for a firm to say it is trading at all in the modern market-place it must have some element of on-line presence. Coupled with this is the explosion of the "population" of Massively Multiplayer ... Keywords: E-commerce, Electronic commerce, Metaverses, Virtual environments, Virtual worlds

Simon Scarle; Sylvester Arnab; Ian Dunwell; Panagiotis Petridis; Aristidis Protopsaltis; Sara Freitas

2012-09-01T23:59:59.000Z

216

Pools of virtual boxes: building campus grids with virtual machines  

Science Conference Proceedings (OSTI)

A campus grid is a critical component of research cyberinfrastructure. A grid facilitates resource sharing, improving collaboration and increasing the capability to address large scale scientific and engineering problems. Resources comprising a grid ... Keywords: campus grid, deployment, distributed computing, high throughput computing, virtual machines, virtualization

David J. Herzfeld; Lars E. Olson; Craig A. Struble

2010-06-01T23:59:59.000Z

217

Uncertainty and Virtual Particles  

NLE Websites -- All DOE Office Websites (Extended Search)

Incertidumbre y partículas virtuales Incertidumbre y partículas virtuales Volver Principal ESTOY PERDIDO!!! El principio de incerteza de Heisenberg: En 1927, Heisenberg enunció una propiedad fundamental de la mecánica cuántica que dice que es imposible medir EN FORMA EXACTA AMBOS, la posición de una partícula y su ímpetu. Cuanto mayor sea la precisión con que determinamos una, menos sabremos de la otra. Este es el llamado Principio de incerteza de Heisenberg. La relación matemática que lo expresa es: Significa que la incertidumbre en la posición (x), multiplicada por la incertidumbre en el momento (p), es mayor o igual que una constante (h-barra dividido por dos.) Este principio puede también ser escrito en términos de energía y tiempo: Significa que la incertidumbre en la energía de una partícula

218

Virtual Optical Comparator  

SciTech Connect

The Virtual Optical Comparator, VOC, was conceived as a result of the limitations of conventional optical comparators and vision systems. Piece part designs for mechanisms have started to include precision features on the face of parts that must be viewed using a reflected image rather than a profile shadow. The VOC concept uses a computer generated overlay and a digital camera to measure features on a video screen. The advantage of this system is superior edge detection compared to traditional systems. No vinyl charts are procured or inspected. The part size and expensive fixtures are no longer a concern because of the range of the X-Y table of the Virtual Optical Comparator. Product redesigns require only changes to the CAD image overlays; new vinyl charts are not required. The inspection process is more ergonomic by allowing the operator to view the part sitting at a desk rather than standing over a 30 inch screen. The procurement cost for the VOC will be less than a traditional comparator with a much smaller footprint with less maintenance and energy requirements.

Thompson, Greg

2008-10-20T23:59:59.000Z

219

Calculating thermal radiation fields from 3D flame reconstruction  

Science Conference Proceedings (OSTI)

Designing fire safety into a building requires a designer to think through issues that include fire ignition, growth and spread. Radiative heat transfer from flames is the dominant method of spread. It is, therefore, necessary to determine the thermal ... Keywords: configuration factor, flame geometry, heat flux, radial basis function, thermal radiation field

Paul Mason; Chris Rogers

2003-02-01T23:59:59.000Z

220

Measurements of Laminar Flame Velocity for Components of Natural Gas  

E-Print Network (OSTI)

Measurements of Laminar Flame Velocity for Components of Natural Gas Patricia Dirrenberger1 flame velocity of components of natural gas, methane, ethane, propane, and nbutane as well as of binary and tertiary mixtures of these compounds proposed as surrogates for natural gas. These measurements have been

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

High-speed Visualization of Flame Propagation in Explosions  

Science Conference Proceedings (OSTI)

Flow visualization data is presented to describe the structure of flames propagating in methane-air explosions in semi-confined enclosures. The role of turbulence is well established as a mechanism for increasing burning velocity by fragmenting the flame ... Keywords: combustion, explosions, high-speed, imaging, laser-sheet

G. K. Hargrave; T. C. Williams; S. Jarvis

2001-12-01T23:59:59.000Z

222

Analyzing and Tracking Burning Structures in Lean Premixed Hydrogen Flames  

E-Print Network (OSTI)

Analyzing and Tracking Burning Structures in Lean Premixed Hydrogen Flames Peer-Timo Bremer, Member levels of turbulence. Due to their unstable nature, lean flames burn in cells separated by locally the turbulence of the burning process with the distribution of burning regions, properly segmented and selected

Pascucci, Valerio

223

Author's personal copy Combustion and Flame 151 (2007) 104119  

E-Print Network (OSTI)

May 2007 Available online 28 June 2007 Abstract Laminar flame speeds of lean H2/CO/CO2 (syngas) fuel Inc. All rights reserved. Keywords: Syngas; Laminar flame speed; CO2 dilution; Reactant preheat). emissions. Synthetic gas (syngas) fuels derived from coal are particularly promising in this regard. Syn

Lieuwen, Timothy C.

224

A Study of Premixed Propagating Flame Vortex Interaction  

Science Conference Proceedings (OSTI)

Experimental data is presented for the interaction between a propagating flame and a simple vortex flow field structure generated in the wake of solid obstacles. The interaction between gas movement and obstacles creates vortex shedding forming a simple ... Keywords: Combustion, Flame/Vortex, PIV, Visualization

G. K. Hargrave; S. Jarvis

2006-04-01T23:59:59.000Z

225

Qualitative physics in virtual environments  

Science Conference Proceedings (OSTI)

In this paper, we describe a new approach to the creation of virtual environments, which uses qualitative physics to implement object behaviour. We adopted Qualitative Process Theory as a qualitative reasoning formalism, due to its representational properties ... Keywords: intelligent virtual environments, modelling and simulation, qualitative physics

Marc Cavazza; Simon Hartley; Jean-Luc Lugrin; Mikael Le Bras

2004-01-01T23:59:59.000Z

226

Virtual stationary timed automata for mobile networks  

E-Print Network (OSTI)

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 ...

Nolte, Tina Ann, 1979-

2009-01-01T23:59:59.000Z

227

Static virtual channel allocation in oblivious routing  

E-Print Network (OSTI)

Most virtual channel routers have multiple virtual channels to mitigate the effects of head-of-line blocking. When there are more flows than virtual channels at a link, packets or flows must compete for channels, either ...

Shim, Keun Sup

228

Flame Spectral Analysis for Boiler Control  

E-Print Network (OSTI)

An instrument has been developed by Tecogen, Inc., to determine the combustion characteristics of individual burners in multiburner installations. The technology is based on measuring the emissions in the ultraviolet (UV) and infrared (IR) spectral 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. These instruments provide data relating to the variations in the IR and UV spectrum with a change in the combustion condition in individuals burners. This paper describes the instruments operation and these tests.

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

1987-09-01T23:59:59.000Z

229

Primitive Virtual Negative Charge  

E-Print Network (OSTI)

Physical fields, such as gravity and electromagnetic field, are interpreted as results from rearrangement of vacuum particles to get the equilibrium of net charge density and net mass density in 4-dimensional complex space. Then, both fields should interact to each other in that physical interaction is considered as a field-to-field interaction. Hence, Mass-Charge interaction is introduced with primitive-virtual negative charge defined for the mass. With the concept of Mass-Charge interaction electric equilibrium of the earth is discussed, especially about the electric field and magnetic field of the earth. For unsettled phenomena related with the earth's gravity, such as antigravity phenomenon, gravity anomalies during the solar eclipses, the connection between geomagnetic storms and earthquakes, etc., possible explanations are discussed.

Kim, Kiyoung

2008-01-01T23:59:59.000Z

230

Primitive Virtual Negative Charge  

E-Print Network (OSTI)

Physical fields, such as gravity and electromagnetic field, are interpreted as results from rearrangement of vacuum particles to get the equilibrium of net charge density and net mass density in 4-dimensional complex space. Then, both fields should interact to each other in that physical interaction is considered as a field-to-field interaction. Hence, Mass-Charge interaction is introduced with primitive-virtual negative charge defined for the mass. With the concept of Mass-Charge interaction electric equilibrium of the earth is discussed, especially about the electric field and magnetic field of the earth. For unsettled phenomena related with the earth's gravity, such as antigravity phenomenon, gravity anomalies during the solar eclipses, the connection between geomagnetic storms and earthquakes, etc., possible explanations are discussed.

Kiyoung Kim

2008-11-04T23:59:59.000Z

231

Turbulence-Flame Interactions in Type Ia Supernovae  

SciTech Connect

The large range of time and length scales involved in type Ia supernovae (SN Ia) requires the use of flame models. As a prelude to exploring various options for flame models, we consider, in this paper, high-resolution three-dimensional simulations of the small-scale dynamics of nuclear flames in the supernova environment in which the details of the flame structure are fully resolved. The range of densities examined, 1 to 8 x 107 g cm-3, spans the transition from the laminar flamelet regime to the distributed burning regime where small scale turbulence disrupts the flame. The use of a low Mach number algorithm facilitates the accurate resolution of the thermal structure of the flame and the inviscid turbulent kinetic energy cascade, while implicitly incorporating kinetic energy dissipation at the grid-scale cutoff. For an assumed background of isotropic Kolmogorov turbulence with an energy characteristic of SN Ia, we find a transition density between 1 and 3 x 107 g cm-3 where the nature of the burning changes ualitatively. By 1 x 107 g cm-3, energy diffusion by conduction and radiation is exceeded, on the flame scale, by turbulent advection. As a result, the effective Lewis Number approaches unity. That is, the flame resembles a laminar flame, but is turbulently broadened with an effective diffusion coefficient, D_T \\sim u' l, where u' is the turbulent intensity and l is the integral scale. For the larger integral scales characteristic of a real supernova, the flame structure is predicted to become complex and unsteady. Implications for a possible transition to detonation are discussed.

Lawrence Berkeley National Laboratory, 1 Cyclotron Road, MS 50A-1148, Berkeley, CA 94720 (Authors 1, 2& 3); Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (Author 4); Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (Author 5); Aspden, Andrew J; Aspden, Andrew J.; Bell, John B.; Day, Marc S.; Woosley, Stan E.; Zingale, Mike

2008-05-27T23:59:59.000Z

232

Turbulence-Flame Interactions in Type Ia Supernovae  

E-Print Network (OSTI)

The large range of time and length scales involved in type Ia supernovae (SN Ia) requires the use of flame models. As a prelude to exploring various options for flame models, we consider, in this paper, high-resolution three-dimensional simulations of the small-scale dynamics of nuclear flames in the supernova environment in which the details of the flame structure are fully resolved. The range of densities examined, 1 to $8 \\times 10^7$ g cm$^{-3}$, spans the transition from the laminar flamelet regime to the distributed burning regime where small scale turbulence disrupts the flame. The use of a low Mach number algorithm facilitates the accurate resolution of the thermal structure of the flame and the inviscid turbulent kinetic energy cascade, while implicitly incorporating kinetic energy dissipation at the grid-scale cutoff. For an assumed background of isotropic Kolmogorov turbulence with an energy characteristic of SN Ia, we find a transition density between 1 and $3 \\times 10^7$ g cm$^{-3}$ where the nature of the burning changes qualitatively. By $1 \\times 10^7$ g cm$^{-3}$, energy diffusion by conduction and radiation is exceeded, on the flame scale, by turbulent advection. As a result, the effective Lewis Number approaches unity. That is, the flame resembles a laminar flame, but is turbulently broadened with an effective diffusion coefficient, $D_T \\sim u' l$, where $u'$ is the turbulent intensity and $l$ is the integral scale. For the larger integral scales characteristic of a real supernova, the flame structure is predicted to become complex and unsteady. Implications for a possible transition to detonation are discussed.

A. J. Aspden; J. B. Bell; M. S. Day; S. E. Woosley; M. Zingale

2008-11-17T23:59:59.000Z

233

Management of high availability services using virtualization.  

E-Print Network (OSTI)

??This thesis examines the use of virtualization in management of high availability services using open source tools. The services are hosted in virtual machines, which… (more)

Braastad, Espen

2006-01-01T23:59:59.000Z

234

Idaho National Laboratory - Hydropower Program- Virtual Hydropower...  

NLE Websites -- All DOE Office Websites (Extended Search)

Virtual Hydropower Prospector do Brasil Access the Virtual Hydropower Prospector do Brasil Disclaimers NOTICE TO USERS The water energy resource and potential project information...

235

Digital Windows: cause + effect between reality + virtuality.  

E-Print Network (OSTI)

??Digital Windows allow real people in the real world to interact with virtual objects in a virtual world through a direct relationship between real-space and… (more)

Sumsion, F

2007-01-01T23:59:59.000Z

236

Performance evaluation and characterization of virtual appliances.  

E-Print Network (OSTI)

??System virtualization technology continues to increase in popularity across the datacenter. Independent Software Vendors (ISVs) are now using virtual machines to deliver software appliances to… (more)

Chen, Zhaoqian

2008-01-01T23:59:59.000Z

237

Modeling of NOx formation in circular laminar jet flames  

E-Print Network (OSTI)

Emissions of oxides of nitrogen (NOx) from combustion devices is a topic of tremendous current importance. The bulk of the review of NOx emissions has been in the field of turbulent jet flames. However laminar jet flames have provided much insight into the relative importance of NOx reaction pathways in non premixed combustion for various flame conditions. The existing models include detailed chemistry kinetics for various species involved in the flame. These detailed models involve very complex integration of hundreds of chemical reactions of various species and their intermediates. Hence such models are highly time consuming and also normally involve heavy computational costs. This work proposes a numerical model to compute the total production of NOx in a non-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 of air entrainment by jet depends upon the Sc number of fuel. The higher the Sc number, the higher is the air entrained which lowers the flame temperature and hence NOx formation. With increasing Sc number, flame volume increases which leads to an increase in the NOx formation. The effect of the Sc number variation on the net production of NOx and flame structure is also investigated. The effect of equilibrium chemistry for CO2 CO + 1/2 O2 and H2O H2 +1/2 O2 on total NOx emission is studied. Also the effect of both CO2 and H2O equilibrium is considered simultaneously and the net x NO formation for propane is 45 ppm. The split between pre-flame and post-flame regions is also investigated. For Propane, 96% of NO emissions occur in the pre-flame region and about 4% in the post-flame region. The model predictions are compared with experimental values of NOx missions reported elsewhere.

Siwatch, Vivek

2005-12-01T23:59:59.000Z

238

Walking > walking-in-place > flying, in virtual environments  

Science Conference Proceedings (OSTI)

Keywords: human factors, locomotion, neural networks, presence, virtual reality, virtual walking, visual cliff

Martin Usoh; Kevin Arthur; Mary C. Whitton; Rui Bastos; Anthony Steed; Mel Slater; Frederick P. Brooks, Jr.

1999-07-01T23:59:59.000Z

239

DETERMINATION OF LITHIUM BY FLAME EMISSION SPECTROMETRY Background Reading: Harris, 7th  

E-Print Network (OSTI)

DETERMINATION OF LITHIUM BY FLAME EMISSION SPECTROMETRY Background Reading: Harris, 7th ed., Chap of this experiment is to acquaint you with flame emission spectrometry. The determination of lithium, and all other. It uses a propane/air flame. #12;Lithium by Flame Emission, Page 2 Identify the burner with its nebulizer

Weston, Ken

240

Application of Flame Doctor to T-Fired Boilers: Feasibility Study  

Science Conference Proceedings (OSTI)

Flame Doctor, a burner diagnostic technology, is a packaged system consisting of hardware and software that ties into existing burner flame scanner systems of wall-fired, cyclone-fired, and turbo-fired boilers to provide real-time assessment of flame quality. This report describes feasibility tests to evaluate Flame Doctor for extension to tangentially fired (T-fired) boiler applications.

2007-03-22T23:59:59.000Z

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Orbit Stability  

NLE Websites -- All DOE Office Websites (Extended Search)

Source Parameter Table Up: APS Storage Ring Parameters Previous: Lattice Definitions Orbit Stability This section lists the specifications of orbit stability. The stored beam...

242

GRAVITATIONALLY UNSTABLE FLAMES: RAYLEIGH-TAYLOR STRETCHING VERSUS TURBULENT WRINKLING  

SciTech Connect

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.

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

243

Program on Technology Innovation: Flame Structure Sensor for PC Combustion - Feasibility Study  

Science Conference Proceedings (OSTI)

The flame-scanner sensor technology incorporated in the Flame Doctor system to provide critical burner state information in pulverized-coal applications is inherently limited in its ability to provide the type of information needed to make very rapid control adjustments. This project investigated the feasibility of two new types of flame-structure sensors for providing supplemental information about flame state that can be used for Flame Doctor system calibration and also for advanced high-speed burner c...

2007-05-16T23:59:59.000Z

244

Modeling and experimental validation of unsteady impinging flames  

Science Conference Proceedings (OSTI)

This study reports on a joint experimental and analytical study of premixed laminar flames impinging onto a plate at controlled temperature, with special emphasis on the study of periodically oscillating flames. Six types of flame structures were found, based on parametric variations of nozzle-to-plate distance (H), jet velocity (U), and equivalence ratio (f). They were classified as conical, envelope, disc, cool central core, ring, and side-lifted flames. Of these, the disc, cool central core, and envelope flames were found to oscillate periodically, with frequency and sound pressure levels increasing with Re and decreasing with nozzle-to-plate distance. The unsteady behavior of these flames was modeled using the formulation derived by Durox et al. [D. Durox, T. Schuller, S. Candel, Proc. Combust. Inst. 29 (2002) 69-75] for the cool central core flames where the convergent burner acts as a Helmholtz resonator, driven by an external pressure fluctuation dependent on a velocity fluctuation at the burner mouth after a convective time delay {tau}. Based on this model, the present work shows that {tau} = [Re[2jtanh{sup -1}((2{delta}{omega}+(1+N)j{omega}{sup 2}-j{omega}{sub 0}{sup 2})/ (2{delta}{omega}+(1-N)j{omega}{sup 2}-j{omega}{sub 0}{sup 2}))]+2{pi}K]/{omega}, i.e., there is a relation between oscillation frequency ({omega}), burner acoustic characteristics ({omega}{sub 0},{delta}), and time delay {tau}, not explicitly dependent on N, the flame-flow normalized interaction coefficient [D. Durox, T. Schuller, S. Candel, Proc. Combust. Inst. 29 (2002) 69-75], because {partial_derivative}t/{partial_derivative}N = 0. Based on flame motion and noise analysis, K was found to physically represent the integer number of perturbations on flame surface or number of coherent structures on impinging jet. Additionally, assuming that {tau}={beta}H/U, where H is the nozzle-to-plate distance and U is the mean jet velocity, it is shown that {beta}{sub Disc}=1.8, {beta}{sub CCC}=1.03, and {beta}{sub Env}=1.0. A physical analysis of the proportionality constant {beta} showed that for the disc flames, {tau} corresponds to the ratio between H and the velocity of the coherent structures. In the case of envelope and cool central core flames, {tau} corresponds to the ratio between H and the mean jet velocity. The predicted frequency fits the experimental data, supporting the validity of the mathematical modeling, empirical formulation, and assumptions made. (author)

Fernandes, E.C.; Leandro, R.E. [Center for Innovation, Technology and Policy Research, Mechanical Engineering Department, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa Codex (Portugal)

2006-09-15T23:59:59.000Z

245

Counterflow diffusion flame synthesis of ceramic oxide powders  

DOE Patents (OSTI)

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

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

1997-01-01T23:59:59.000Z

246

Counterflow diffusion flame synthesis of ceramic oxide powders  

DOE Patents (OSTI)

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

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

1997-07-22T23:59:59.000Z

247

Virtual urban traffic network simulator  

E-Print Network (OSTI)

In this project, I designed and implemented a virtual urban traffic network simulator. The simulator serves as a testbed for human-subject experiments to determine driver behavior in road networks and also as a platform ...

Uh, Jason (Jason J.)

2011-01-01T23:59:59.000Z

248

Virtual workplaces : when metaphors breakdown  

E-Print Network (OSTI)

Our model of work is shaped by the places we choose to work and the tools we choose to work with. As we introduce new technologies and build new environments our model is changing. Today's virtual workplaces are grounded ...

Gallemore, Thomas W. I. (Thomas Wilson Ira), 1969-

1998-01-01T23:59:59.000Z

249

Virtual workspaces in the grid  

Science Conference Proceedings (OSTI)

Despite significant progress in the development of Grid infrastructure, the provisioning of a customized and controllable remote execution environment remains an open issue. This paper introduces the concept of a virtual workspace, a configurable execution ...

Katarzyna Keahey; Ian Foster; Timothy Freeman; Xuehai Zhang; Daniel Galron

2005-08-01T23:59:59.000Z

250

Real illumination from virtual environments  

Science Conference Proceedings (OSTI)

We introduce a method for actively controlling the illumination in a room so that it is consistent with a virtual world. In combination with a high dynamic range display, the system produces both uniform and directional illumination at intensity levels ...

Abhijeet Ghosh; Matthew Trentacoste; Helge Seetzen; Wolfgang Heidrich

2005-06-01T23:59:59.000Z

251

FLAMES IN TYPE Ia SUPERNOVA: DEFLAGRATION-DETONATION TRANSITION IN THE OXYGEN-BURNING FLAME  

Science Conference Proceedings (OSTI)

The flame in a Type Ia supernova is a conglomerate structure that, depending on density, may involve separate regions of carbon, oxygen, and silicon burning, all propagating in a self-similar, subsonic front. The separation between these three burning regions increases as the density declines until eventually, below about 2 x 10{sup 7} g cm{sup -3}, only carbon burning remains active, the other two burning phases having 'frozen out' on stellar scales. Between 2 and 3 x 10{sup 7} g cm{sup -3}, however, there remains an energetic oxygen-burning region that trails the carbon burning by an amount that is sensitive to the turbulence intensity. As the carbon flame makes a transition to the distributed regime (Karlovitz number {approx}> 10), the characteristic separation between the carbon- and oxygen-burning regions increases dramatically, from a fraction of a meter to many kilometers. The oxygen-rich mixture between the two flames is created at a nearly constant temperature, and turbulence helps to maintain islands of well-mixed isothermal fuel as the temperature increases. The delayed burning of these regions can be supersonic and could initiate a detonation.

Woosley, S. E. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Kerstein, A. R. [Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551 (United States); Aspden, A. J., E-mail: woosley@ucolick.org, E-mail: arkerst@sandia.gov, E-mail: ajaspden@lbl.gov [Center for Computational Sciences and Engineering, Lawrence Berkeley National Laboratory, CA 94720 (United States)

2011-06-10T23:59:59.000Z

252

Phone virtualization using a microkemel hypervisor  

Science Conference Proceedings (OSTI)

Virtualization of multi-core hardware is becoming important in enterprise computing using hypervisors such as VMware or Xen. For desktop phones, virtualization can be used to simultaneously run multiple phone OSes on the same desktop phone, and provide ... Keywords: L4, OKL4, embedded microkernel, hypervisor, phone virtualization, virtualization

Amrit Acharya; John Buford; Venky Krishnaswamy

2009-12-01T23:59:59.000Z

253

Virtualization: a way towards dynamic IT  

Science Conference Proceedings (OSTI)

This paper focuses on different aspects of Virtualization that will help the IT & development organization to become more strategic to their business. The Dynamic IT strategy helps businesses enhance the capability and efficiency of their people, processes, ... Keywords: virtualization, virtualization software and applications, virtualization types

U. Pawar; M. Bhelotkar

2011-02-01T23:59:59.000Z

254

Children's residential exposures to flame retardants, pesticides and pesticide degradation products, and the relationship of pesticides with autonomic nervous system functioning  

E-Print Network (OSTI)

diphenyl ethers: a flame-retardant additive in severaldiphenyl ether (PBDE) flame retardants. Neurotoxicology. 28,diphenyl ethers: a flame-retardant additive in several

Quiros Alcala, Lesliam

2010-01-01T23:59:59.000Z

255

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)

et al. : Combustion-derived flame generated ultrafine sootacute inhalation of diffusion flame soot particles: cellularAccess Combustion-derived flame generated ultrafine soot

2013-01-01T23:59:59.000Z

256

Review: Virtual machine tools and virtual machining-A technological review  

Science Conference Proceedings (OSTI)

Virtual manufacturing systems provide a useful means for products to be manufactured 'right the first time' without the need of physical testing on the shop floor. Earlier research was mostly on developing a virtual manufacturing environment. Over the ... Keywords: Machining simulation, Virtual machine tool, Virtual machining, Virtual system

Aini Abdul Kadir; Xun Xu; Enrico Hämmerle

2011-06-01T23:59:59.000Z

257

NETL: Gasification Systems - Real Time Flame Monitoring of Gasifier...  

NLE Websites -- All DOE Office Websites (Extended Search)

Real Time Flame Monitoring of Gasifier Burner and Injectors Project No.: DE-FC26-02NT41585 Gas Technology Institute is developing a reliable, practical, and cost effective means to...

258

Adaptive low Mach number simulations of nuclear flame microphysics  

Science Conference Proceedings (OSTI)

We introduce a numerical model for the simulation of nuclear flames in Type Ia supernovae. This model is based on a low Mach number formulation that analytically removes acoustic wave propagation while retaining the compressibility effects resulting ...

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

2004-04-01T23:59:59.000Z

259

Surface wettability studies of PDMS using flame plasma treatment  

E-Print Network (OSTI)

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 ...

Wang, Xin C

2009-01-01T23:59:59.000Z

260

NETL: Investigation on Flame Characteristics and Burner Operability...  

NLE Websites -- All DOE Office Websites (Extended Search)

Oxy-Combustion CO2 Emissions Control Investigation on Flame Characteristics and Burner Operability Issues of Oxy-Fuel Combustion Project No.: DE-FE0002402 NETL has partnered with...

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Flame size, heat release, and smoke points in materials ...  

Science Conference Proceedings (OSTI)

... to flame area was 0.25 cm for propane, ethylene, and ... means to insure a steady state condition (or ... Pergamon Press, New York, 1979, pp., 185–195. ...

2008-08-20T23:59:59.000Z

262

Scalar dissipation rate based flamelet modelling of turbulent premixed flames  

E-Print Network (OSTI)

closures . . . . . . . . . . . . . . . 98 7.2 RANS of planar one–dimensional flames . . . . . . . . . . . . . . 99 7.2.1 Computational details . . . . . . . . . . . . . . . . . . . . 99 7.2.2 Results and discussion... ). . . . . . . . . . . . . . . . . . . . . . 129 7.21 The contour plot of temperature (K) from the Bunsen flame calcu- lations for case F3. The plot for the entire computational domain (top) and the region close to the nozzle exit (bottom) are shown. 130 7.22 The mean progress variable, c, using...

Kolla, Hemanth

2010-03-16T23:59:59.000Z

263

Coupling of diffusion flame structure to an unsteady vortical flowfield  

Science Conference Proceedings (OSTI)

A laminar methane-air diffusion flame is interacted with vortices of various sizes and strengths in order to better understand unsteady stretch and history effects on turbulent flames. The nitrogen-diluted fuel stream of a Wolfhard-Parker slot burner is acoustically forced, producing repeatable two-dimensional vortices that strain and curve the flame. Phase locked, planar laser-induced fluorescence (PLIF) diagnostics are used to quantify the response of the OH-radical to the vortex-induced stretch. Acetone PLIF images are used to clarify the relationship between the vortex structure and the flame. The results show that the vortex causes significant variations in the OH layer thickness. In particular, negative strain produces a doubling of the flame thickness. Such large increases in OH layer thickness are not predicted by the laminar flamelet model (LFM) because negative strain rates cannot be simulated using standard counterflow flamelet geometry. Local extinction of the OH layer due to high strain is observed near the flame base. Peak OH mole fraction levels vary considerably more than adiabatic LFM predictions. In particular, the peak OH decreases by a factor of two with downstream distance. This decrease is believed due to dilution of reactants by combustion products formed elsewhere in the flow. A simplified model is proposed, which shows the OH concentration is sensitive to product dilution through the scalar dissipation rate.

C. J. Mueller; R. W. Schefer

1998-08-02T23:59:59.000Z

264

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

E-Print Network (OSTI)

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...

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

2012-01-01T23:59:59.000Z

265

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

Science Conference Proceedings (OSTI)

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

Veloo, Peter S.; Wang, Yang L.; Egolfopoulos, Fokion N. [Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA 90089-1453 (United States); Westbrook, Charles K. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States)

2010-10-15T23:59:59.000Z

266

Combustor oscillation pressure stabilizer  

DOE Patents (OSTI)

In accordance with the objective of the present invention, the active control of unsteady combustion induced oscillations in a combustion chamber fired by a suitable fuel and oxidizer mixture, such as a hydrocarbon fuel and air mixture, is provided by restructuring and moving the position of the main flame front and thereby increasing the transport time and displacing the pressure wave further away from the in-phase relationship with the periodic heat release. The restructuring and repositioning of the main flame are achieved by utilizing a pilot flame which is pulsed at a predetermined frequency corresponding to less than about one-half the frequency of the combustion oscillation frequency with the duration of each pulse being sufficient to produce adequate secondary thermal energy to restructure the main flame and thereby decouple the heat release from the acoustic coupling so as to lead to a reduction in the dynamic pressure amplitude. The pulsating pilot flame produces a relatively small and intermittently existing flame front in the combustion zone that is separate from the oscillating main flame front but which provides the thermal energy necessary to effectively reposition the location of the oscillating main flame front out of the region in the combustion zone where the acoustic coupling can occur with the main flame and thereby effectively altering the oscillation-causing phase relationship with the heat of combustion.

Gemmen, R.S.; Richards, G.A.; Yip, M.T.J.; Robey, E.; Cully, S.R.; Addis, R.E.

1996-12-31T23:59:59.000Z

267

Reti attive di distribuzione: le applicazioni Virtual Power Plant e Virtual Utility.  

E-Print Network (OSTI)

??Il presente lavoro si occupa di nuove applicazioni per la gestione e l’ottimizzazione di risorse distribuite, così dette Virtual Power Plant (VPP) o Virtual Utility… (more)

Baroncelli, Paolo

2005-01-01T23:59:59.000Z

268

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

E-Print Network (OSTI)

Joulin, P. Ronney, Combust. Flame 84 (1991) 411–422. [9] I.R. A. Strehlow, Combust. Flame 49 (1983) 123–140. [11] B.F. A. Williams, Combust. Flame 33 (1978) 33–45. [12] T.

Grcar, Joseph F

2008-01-01T23:59:59.000Z

269

Dimensionality estimate of the manifold in chemical composition space for a turbulent premixed H2+air flame  

E-Print Network (OSTI)

W. H. ; Barton, P. I. Combust Flame 2002, 128, 270–291. [8]Maas, U. ; Pope, S. B. Combust Flame 1992, 88, 239–264. [11]B. ; Pope, S. B. Combust Flame 1998, 112, 85–112. [18] Bray,

Tonse, Shaheen R.; Brown, Nancy J.

2003-01-01T23:59:59.000Z

270

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

E-Print Network (OSTI)

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.

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

2009-01-01T23:59:59.000Z

271

Virtual instrumentation to study galaxies  

E-Print Network (OSTI)

The MIGALE project (http://www.sai.msu.su/migale) provides databases and data analysis tools to study the evolution of galaxies from z=1 to z=0. It develops and maintain a general database, HyperLeda, to give a homogenized parameterization for 3 million objects, and several archives or specialized databases. It also develops tools to analyse on-the-fly data extracted from the database or obtained through the Virtual Observatory (Virtual Instruments). The package made for this project, Pleinpot, is distributed as open source.

Ph. Prugniel; I. Chilingarian; H. Flores; J. Guibert; R. Haigron; I. Jegouzo; F. Royer; F. Tajahmady; G. Theureau; J. Vetois

2004-10-13T23:59:59.000Z

272

Lewis number effects on turbulent premixed flame structure  

DOE Green Energy (OSTI)

The influence of the Lewis number on turbulent flame front geometry is investigated in a premixed turbulent stagnation point flame. A laser tomography technique is used to obtain the flame shape, a fractal analysis of the multiscale flame edges is performed and the distribution of local flame front curvature is determined. Lean H[sub 2]/Air and C[sub 3]H[sub 8]/Air mixtures with similar burning rates were investigated with Lewis numbers of 0.33 and 1.85 respectively. At the conditions studied the laminar H[sub 2]/Air mixture is unstable and a cellular structure is observed. Turbulence in the reactant is generated by a perforated plate and the turbulent length scale (3mm) and intensity (7%) at the nozzle exit are fixed. The equivalence ratio is set so that the burning velocity is the same for all the cases. Results show clearly that the turbulent flame surface area is dependent on the Lewis number. For a Lewis number less than unity surface area production is observed. The shape of the flame front curvature distribution is not found to be very sensitive to the Lewis number. For the H[sub 2]/Air mixture the distribution is skewed toward the positive values indicating the presence of cusps while for the C[sub 3]H[sub 8]/Air mixture the distribution is more symmetrical. In both cases the average curvature is found to be zero, and if the local burning speed varies linearly with curvature, the local positive and negative burning velocity variations due to curvature will balance.

Goix, P.J. (Centre National de la Recherche Scientifique (CNRS), 230 - Mont-Saint-Aignan (France). URA CORIA); Shepherd, I.G. (Lawrence Berkeley Lab., CA (United States))

1992-09-01T23:59:59.000Z

273

Lewis number effects on turbulent premixed flame structure  

DOE Green Energy (OSTI)

The influence of the Lewis number on turbulent flame front geometry is investigated in a premixed turbulent stagnation point flame. A laser tomography technique is used to obtain the flame shape, a fractal analysis of the multiscale flame edges is performed and the distribution of local flame front curvature is determined. Lean H{sub 2}/Air and C{sub 3}H{sub 8}/Air mixtures with similar burning rates were investigated with Lewis numbers of 0.33 and 1.85 respectively. At the conditions studied the laminar H{sub 2}/Air mixture is unstable and a cellular structure is observed. Turbulence in the reactant is generated by a perforated plate and the turbulent length scale (3mm) and intensity (7%) at the nozzle exit are fixed. The equivalence ratio is set so that the burning velocity is the same for all the cases. Results show clearly that the turbulent flame surface area is dependent on the Lewis number. For a Lewis number less than unity surface area production is observed. The shape of the flame front curvature distribution is not found to be very sensitive to the Lewis number. For the H{sub 2}/Air mixture the distribution is skewed toward the positive values indicating the presence of cusps while for the C{sub 3}H{sub 8}/Air mixture the distribution is more symmetrical. In both cases the average curvature is found to be zero, and if the local burning speed varies linearly with curvature, the local positive and negative burning velocity variations due to curvature will balance.

Goix, P.J. [Centre National de la Recherche Scientifique (CNRS), 230 - Mont-Saint-Aignan (France). URA CORIA; Shepherd, I.G. [Lawrence Berkeley Lab., CA (United States)

1992-09-01T23:59:59.000Z

274

Aromatics Oxidation and Soot Formation in Flames  

SciTech Connect

This project is concerned with the kinetics and mechanisms of aromatics oxidation and the growth process to polycyclic aromatic hydrocarbons (PAH) of increasing size, soot and fullerenes formation in flames. The overall objective of the experimental aromatics oxidation work is to extend the set of available data by measuring concentration profiles for decomposition intermediates such as phenyl, cyclopentadienyl, phenoxy or indenyl radicals which could not be measured with molecular-beam mass spectrometry to permit further refinement and testing of benzene oxidation mechanisms. The focus includes PAH radicals which are thought to play a major role in the soot formation process while their concentrations are in many cases too low to permit measurement with conventional mass spectrometry. The radical species measurements are used in critical testing and improvement of a kinetic model describing benzene oxidation and PAH growth. Thermodynamic property data of selected species are determined computationally, for instance using density functional theory (DFT). Potential energy surfaces are explored in order to identify additional reaction pathways. The ultimate goal is to understand the conversion of high molecular weight compounds to nascent soot particles, to assess the roles of planar and curved PAH and relationships between soot and fullerenes formation. The specific aims are to characterize both the high molecular weight compounds involved in the nucleation of soot particles and the structure of soot including internal nanoscale features indicative of contributions of planar and/or curved PAH to particle inception.

Howard, J. B.; Richter, H.

2005-03-29T23:59:59.000Z

275

Soot profiles in boundary-layer flames  

DOE Green Energy (OSTI)

Carbon particulate volume fractions and approximate particle size distributions are measured in a free laminar combusting boundary layer for liquid hydrocarbon fuels (n-heptane, iso-octane, cyclohexane, cyclohexene, toluene) and polymethylmethacrylate (PMMA). A multiwavelength laser transmission technique determines a most probable radius and the total particle concentration, which are two parameters in an assumed form for the size distribution. In the combusting boundary layer, a sooting region exists between the pyrolyzing fuel surface and the flame zone. The liquid fuel soot volume fractions, f/sub v/, range from f/sub v/ approx. 10/sup -7/ for n-heptane, a paraffin, to f/sub v approx. 10/sup -5/ for toluene, an aromatic. The PMMA volume fractions, f/sub v/ approx. 5 X 10/sup -7/, are approximately the same as the values previously reported for pool fires. The soot volume fractions increase with height; convection of carbon particles downstream widens the soot region with height. For all fuels tested, the most probable radius is between 20 nm and 50 nm, and it changes only slightly with height and distance from the fuel surface.

Beier, R.A.; Pagni, P.J.

1981-12-01T23:59:59.000Z

276

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

Science Conference Proceedings (OSTI)

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.

Ahsan R. Choudhuri

2006-08-07T23:59:59.000Z

277

On the motion of the center of mass of a spherical turbulent premixed flame  

DOE Green Energy (OSTI)

The movement of the center of mass of a premixed statistically spherical flame in the wrinkled-laminar flame regime has been examined. When the flame is small (or comparable) to the integral scale of the turbulence, the flame ball is convected as a whole by the turbulent eddy. When the flame grows to a size large compared to the integral scale, the flame center of motion is not affected by the turbulence. This phenomenon has been explained in terms of the phase coherence of the local turbulent convection velocity at the flame front. When the flame is small, the turbulent velocity is coherent over the entire flame surface; as a result, the flame is convected as a whole by the turbulent eddy. When the flame is large, the velocity at the different area elements of the flame front is independent of each other. The center of mass velocity, which is an aggregate of the velocities at the different elements, therefore, tends to the mean velocity and is independent of the turbulence. A theory for predicting the variance of the flame center velocity has been developed. The prediction is in good agreement with the experimental results. 12 refs., 5 figs.

Cheng, W. K.; Hainsworth, E.

1988-01-01T23:59:59.000Z

278

Virtual Money Systems: a Phenomenal Analysis  

E-Print Network (OSTI)

In the development of virtual communities, a new phenomenon of virtual money is observed and presented high importance to both e-commerce and e-society fields. This paper, as a pioneer research, has attempted to make a phenomenal analysis on the existing virtual money systems. By the analysis, this paper has defined what virtual money is, what its general models are, and how its existing systems work. By the analysis, the features of existing virtual money systems are abstracted and their problems are summarized. Driven by the motivation of utilizing and improving the existing virtual money systems, this paper has outlined a novel generic virtual money system model called Common Money (CONEY) to resolve the problems that bother the existing virtual money systems. Finally, further interesting issues for future research are given. 1.

Jingzhi Guo; Angelina Chow

2008-01-01T23:59:59.000Z

279

A Web-Based Virtual Lighting Simulator  

NLE Websites -- All DOE Office Websites (Extended Search)

A Web-Based Virtual Lighting Simulator Title A Web-Based Virtual Lighting Simulator Publication Type Conference Paper LBNL Report Number LBNL-51065 Year of Publication 2002 Authors...

280

Virtual articulation and kinematic abstraction in robotics  

E-Print Network (OSTI)

This thesis presents the theory, implementation, novel applications, and experimental validation of a general-purpose framework for applying virtual modifications to an articulated robot, or virtual articulations. These ...

Vona, Marsette Arthur, 1977-

2009-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Virtualized application performance prediction using system metrics  

E-Print Network (OSTI)

Virtualized datacenter administrators would like to consolidate virtual machines (VMs) onto as few physical hosts as possible in order to decrease costs, but must leave enough physical resources for each VM to meet application ...

Wanderman-Milne, Skye A

2012-01-01T23:59:59.000Z

282

Virtual Testing for Smart Buildings  

Science Conference Proceedings (OSTI)

Smart buildings promise to revolutionize the way we live. Applications ranging from climate control to fire management can have significant impact on the quality and cost of these services. However, smart buildings and any technology with direct effect ... Keywords: Virtual testing, Smart buildings, HVAC, Pervasive computing

Julien Bruneau; Charles Consel; Marcia O'Malley; Walid Taha; Wail Masry Hannourah

2012-06-01T23:59:59.000Z

283

The human agent virtual environment  

Science Conference Proceedings (OSTI)

In this paper we describe a multi-agent simulation called the Human Agent Virtual Environment (or HAVE). HAVE is a test bed to explore agent-environment interaction in multi-agent simulation for defence applications. The primary research driver in the ... Keywords: agents and cognitive models, defence, multi-agent simulation and modeling

Michael Papasimeon; Adrian R. Pearce; Simon Goss

2007-05-01T23:59:59.000Z

284

Empathy in virtual learning environments  

Science Conference Proceedings (OSTI)

How do we engage teachers and learners in the learning process and what are the benefits of this? How do we get students to learn? Many academic institutions of all levels are asking these questions. Throughout the years new teaching methodologies ... Keywords: Second Life, VLEs, e-learning, empathy, engagement, online learning, teaching methodologies, virtual learning environments

Judith Molka-Danielsen; Bryan W. Carter; Alastair Creelman

2009-02-01T23:59:59.000Z

285

Virtual Fieldwork Using Google Earth  

E-Print Network (OSTI)

Virtual Fieldwork Using Google Earth Advanced Techniques #12;Digital Explorer 1 Gough Square London Fieldwork Using Google Earth compiled by Jamie Buchanan-Dunlop Digital Explorer 71 Regent Studios 8 Andrews Buchanan-Dunlop © 2008 Google © 2008 Ricardo Sgrillo All rights reserved cover design by rob `at

Smith-Konter, Bridget

286

Dynamic virtual credit card numbers  

Science Conference Proceedings (OSTI)

Theft of stored credit card information is an increasing threat to e-commerce.We propose a dynamic virtual credit card number scheme that reduces the damage caused by stolen credit card numbers. A user can use an existing credit card account to generate ... Keywords: credit card theft, e-commerce

Ian Molloy; Jiangtao Li; Ninghui Li

2007-02-01T23:59:59.000Z

287

Instructions for Using Virtual Private Network  

Energy.gov (U.S. Department of Energy (DOE))

Virtual Private Network provides access to network drives, and is recommended for use only from a ETIS-provided laptop. 

288

Virtual Reality for Manufacturing Case Studies  

Science Conference Proceedings (OSTI)

Virtual Reality for Manufacturing - Case Studies. Sandy Ressler National Institute of Standards and Technology sressler@nist.gov. ...

289

Lean premixed flames for low NO{sub x} combustors  

DOE Green Energy (OSTI)

The overall objectives of the research at Purdue are to: obtain a reduced mechanism description of high pressure NO formation chemistry using experiments and calculations for laminar lean premixed methane air flames, develop a statistical model of turbulence NO chemistry interactions using a Bunsen type jet flame, and utilize the high pressure chemistry and turbulence models in a commercial design code, then evaluate its predictions using data from an analog gas turbine combustor. Work to date has resulted in the following achievements: spatially resolved measurements of NO in high-pressure high-temperature flat flames, plus evaluation of the influence of flame radiation on the measured temperature profile; measurements of temperature and velocity PDFs for a turbulent methane/air flame were obtained for the first time, under operating conditions which allow their study in the distributed regimes, and the increase in EINO{sub x} with equivalence ratio predicted using a chemical kinetics model; and simulation of non-reacting combustor flow fields from ambient to elevated pressure and temperature conditions and comparison of those results with experimental velocity profiles.

Sojka, P.; Tseng, L.; Bryyjak, J. [Purdue Univ., Lafayette, IN (United States). Thermal Sciences and Propulsion Center] [and others

1995-12-31T23:59:59.000Z

290

LES of Sandia Flame D with Eulerian PDF and Finite-Rate Chemistry  

E-Print Network (OSTI)

Barlow, R. S. , 2003. Sandia piloted CH 4 /air ?ame D data -LES of Sandia Flame D with Eulerian PDF and Finite-RatePaper: 05F-33 LES of Sandia Flame D with Eulerian PDF and

Bisetti, Fabrizio; Chen, J Y

2005-01-01T23:59:59.000Z

291

Analysis of Reaction-Diffusion Systems for Flame Capturing in Type Ia Supernova Simulations  

E-Print Network (OSTI)

We present a study of numerical behavior of a thickened flame used in Flame Capturing (FC, Khokhlov (1995)) for tracking thin unresolved physical flames in deflagration simulations. We develop a steady-state procedure for calibrating the flame model used, and test it against analytical results. We observe numerical noises generated by original realization of the technique. Alternative artificial burning rates are discussed, which produce acceptably quiet flames. Two new quiet models are calibrated to yield required "flame" speed and width, and further studied in 2D and 3D setting. Landau-Darrieus type instabilities of the flames are observed. One model also shows significantly anisotropic propagation speed on the grid, both effects increasingly pronounced at larger matter expansion as a result of burning; this makes the model unacceptable for use in type Ia supernova simulations. Another model looks promising for use in flame capturing at fuel to ash density ratio of order 3 and below. That "Model B" yields f...

Zhiglo, Andrey V

2009-01-01T23:59:59.000Z

292

Effects of curvature and strain on a lean premixed methane-hydrogen-air flame  

E-Print Network (OSTI)

The elemental flame is a subgrid model for turbulent combustion, parameterized by time-varying strain rate and curvature. This thesis develops the unsteady one-dimensional governing equations for the elemental flame ...

Speth, Raymond L., 1981-

2006-01-01T23:59:59.000Z

293

STUDIES OF WALL FLAME QUENCHING AND HYDROCARBON EMISSIONS IN A MODEL SPARK IGNITION ENGINE  

E-Print Network (OSTI)

Cylinder Engine Study with Propane as a Fuel," SAE Paper No.Wall-Quenching of Laminar Propane Flames as a Function ofQuenching Distance of Propane-Air Flames in a Constant-

Ishikawa, Nobuhiko

2011-01-01T23:59:59.000Z

294

Flame Arrester Evaluation for E-Diesel Fuel Tanks: September 3, 2002 - May 28, 2003  

DOE Green Energy (OSTI)

An evaluation of various flame arresters for use with E-Diesel fuel was conducted on four diesel fuel tanks selected to represent typical fuel tank and fill neck designs. Multiple flame arresters were tested on each fuel tank.

Weyandt, N.; Janssens, M. L.

2003-06-01T23:59:59.000Z

295

Transportation planning: A virtual reality  

SciTech Connect

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.``

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

296

A new approach to virtual palpation  

Science Conference Proceedings (OSTI)

In this paper, a new approach to virtual medical abdominal palpation has been introduced. Firstly, we describe palpation as a medical procedure. Then, we analyze the necessity of virtual palpation. Next, we present our survey on the existing work on ... Keywords: function-based, haptic device, palpation, respiration, virtual reality

Shamima Yasmin; Alexei Sourin

2012-12-01T23:59:59.000Z

297

Teaching Virtual Reality: Why and How?  

Science Conference Proceedings (OSTI)

This article looks at the teaching aspects of virtual reality, as opposed to the use of virtual reality as a teaching tool (in virtual teaching environments). It is motivated by a perceived need for clarity, focus, and dialogue that are lacking within ...

Grigore C. Burdea

2004-08-01T23:59:59.000Z

298

Virtual worlds as a medium for advertising  

Science Conference Proceedings (OSTI)

Online virtual worlds, such as Second Life, are rapidly becoming recognized as a technology of substantial future importance for marketers and advertisers. Many of these virtual worlds provide the potential medium for very rich and varied new and enhanced ... Keywords: MMOG, advertising, marketing, online game, second life, virtual world

Stuart Barnes

2007-10-01T23:59:59.000Z

299

Virtual 95th AOCS Annual Meeting & Expo  

Science Conference Proceedings (OSTI)

2004 CD-ROM contains over 120 presentations from many oral and poster presenters from the 95th AOCS Annual Meeting & Expo. Virtual 95th AOCS Annual Meeting & Expo Virtual Meetings DVD & CD-ROMs Expanding on the previous Virtual AOCS Annual Meeting &

300

Scaling and efficiency of PRISM in adaptive simulations of turbulent premixed flames  

E-Print Network (OSTI)

dimensional premixed flames," Sandia National Labora­ toriesand plasma kinetics," Sandia National Laboratories Reporttransport properties," Sandia National Laboratories Report

1999-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Scaling and efficiency of PRISM in adaptive simulations of turbulent premixed flames  

E-Print Network (OSTI)

dimensional premixed flames," Sandia National Labora- toriesand plasma kinetics," Sandia National Laboratories Reporttransport properties," Sandia National Laboratories Report

Tonse, Shaheen R.

2011-01-01T23:59:59.000Z

302

Coordinate-free description of corrugated flames with realistic density drop at the front  

E-Print Network (OSTI)

The complete set of hydrodynamic equations for a corrugated flame front is reduced to a system of coordinate-free equations at the front using the fact that vorticity effects remain relatively weak even for corrugated flames. It is demonstrated how small but finite flame thickness may be taken into account in the equations. Similar equations are obtained for turbulent burning in the flamelet regime. The equations for a turbulent corrugated flame are consistent with the Taylor hypothesis of stationary external turbulence.

Vitaly Bychkov; Maxim Zaytsev; V'yacheslav Akkerman

2012-10-30T23:59:59.000Z

303

Flame Synthesis of One-Dimensional Metal Oxide Nanomaterials  

NLE Websites -- All DOE Office Websites (Extended Search)

Synthesis of One-Dimensional Metal Oxide Nanomaterials Synthesis of One-Dimensional Metal Oxide Nanomaterials Alexei V. Saveliev Dept. of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695, USA Robust, scalable, and energy efficient methods of nanomaterial synthesis are needed to meet the demands of current and potential applications. Flames have been successfully applied for the synthesis of metal oxide and ceramic nanopowders largely composed of spherical particles and their aggregates. In recent years, premixed and diffusion flames have been employed for the synthesis of 1-D carbon nanoforms such as carbon fibers and carbon nanotubes. The extension of flame methods to gas phase and solid support synthesis of 1-D inorganic nanoforms is of great interest and significance. This talk presents

304

A lattice Boltzmann algorithm for calculation of the laminar jet diffusion flame  

Science Conference Proceedings (OSTI)

A new two-distribution lattice Boltzmann equation (LBE) algorithm is presented to solve the laminar diffusion flames within the context of Burke-Schumann flame sheet model. One distribution models the transport of the Schvab-Zeldovich coupling function, ... Keywords: TVD scheme, laminar diffusion flame, lattice Boltzmann equation, quasi-incompressible flow

Taehun Lee; Ching-Long Lin; Lea-Der Chen

2006-06-01T23:59:59.000Z

305

NO sub x destruction in diffusion flame environments  

Science Conference Proceedings (OSTI)

This research is concerned with reburning, which is an NO{sub x} abatement technique involving the injection of secondary fuel into the post flame of a furnace. The specific objectives of this research are to determine whether heterogeneities inherent in diffusion flame environments can be exploited to achieve greater reductions in NO than can be achieved in premixed systems. The research project described here is but a first step to explore this question, and should be viewed more as a screening study rather than as completed research, the results of which are completely understood. The problem was attacked through both experimentation and theoretical modeling. Experiments employed a bench scale, laminar, counter-flow, diffusion flame, which was designed to simulate the stretched diffusion flamelets that arise at the interface between turbulent fuel and oxidant jets. Data gathered were of two types. First, NO destruction from the integral system was investigated through parametric studies in which only inlet and outlet species and flows were measured. Three different experimental configurations were examined, under a wide range of operating conditions, with emphasis on reburning under overall fuel lean conditions. Second, in order to gain insight into the observed phenomena, detailed axial profiles of major and minor species were measured for one configurations. Theoretical modeling consisted of computer simulations which attempt to describe the experimental configuration as an infinitely wide flat flame. This yielded predictions of axial profiles but was not readily adaptable for (integral) predictions of total NO destroyed in our flame. The model employed detailed chemical reactions, and was also used to determine regimes in which ignition occurs under diffusion flame conditions. 30 refs., 31 figs., 19 tabs.

Wendt, J.O.L.; Lin, W.C.; Mwabe, P.

1991-07-31T23:59:59.000Z

306

Real Time Flame Monitoring of Gasifier Burner and Injectors  

NLE Websites -- All DOE Office Websites (Extended Search)

Real Time Flame Monitoring of Gasifier Real Time Flame Monitoring of Gasifier Burner and Injectors Background The Gasification Technologies Program at the National Energy Technology Laboratory (NETL) supports research and development (R&D) in the area of gasification-a process whereby carbon-based materials (feedstocks) such as coal are converted into synthesis gas (syngas), which is separated into hydrogen (H 2 ) and carbon dioxide (CO 2 ) gas streams in a combustion turbine-generator as a way to generate clean electricity while

307

Flame acceleration and transition to detonation in channels  

DOE Green Energy (OSTI)

Experimental results are reported for combustion of pre-mixed H/sub 2/-air mixtures in a 136 m/sup 3/ channel and a 1:12.6 linear scale model. Test variables include H/sub 2/-air equivalence ratio, obstacles and degree of transverse venting. The results show that flame acceleration is increased by sensitive mixtures, presence of obstacles, large scales, and insufficient venting. The results also support the hypothesis that deflagration to detonation transition (DDT) can occur if the ratio of detonation cell width to channel width is less than a critical value, provided that the flame speed prior to transition has approached the isobaric sound speed.

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

1987-01-01T23:59:59.000Z

308

Structure of Partially Premixed Flames Using Detailed Chemistry Simulations  

E-Print Network (OSTI)

State-of-the-art reacting-flow computations have to compromise either on the detail of chemical reactions or on the dimensionality of the solution, while experiments in flames are limited by the flow accessibility and provide at best a limited number of observables. In the present work, the partially premixed laminar flame structure is examined using a detailed-chemistry, one-dimensional simulation. The computational results are compared to unpublished single-point multiscalar measurements 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 to analyze the spatial and scalar flame structure under the overarching concept of flamelets. The computations are based on the Cantera open-source software package developed at CalTech by D. Goodwin, and incorporating the GRI 3.0 chemical kinetic mechanism utilizing 325 chemical reactions and 53 species for methane combustion. Cross-transport effects as well as an optically-thin radiation model are included in the calculations. Radiation changes the flame profiles due to its effect on temperature, and the attendant effects on a number of species. Using the detailed analysis of different reaction rates, the adiabatic and radiative nitric oxide concentrations are compared. The cross-transport effects, i.e. Soret and Dufour, were studied in detail. The Soret term has a small but important effect on the flame structure through a reduction of the hydrogen mass fraction, which changes the conserved scalar values. Based on the flamelet approach and a unique formulation of the conserved scalar, the flame thermochemistry can be analyzed and understood. A number of interesting effects on the flame thermochemistry can be discerned in both experiments and computations when the premixture strength is varied. An increase in premixing results in a counterintuitive decrease in intermediate species such as carbon monoxide and hydrogen, as well as an expected increase in nitric oxide concentrations. Good agreement is found between experiments and calculations in scalar space, while the difference in dimensionality between axisymmetric measurements and opposed jet computations makes comparison in physical space tentative.

Kluzek, Celine D.

2009-08-01T23:59:59.000Z

309

INVESTIGATION ON THE FLAME EXTINCTION LIMIT OF FUEL BLENDS  

SciTech Connect

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.

Ahsan R. Choudhuri

2005-02-01T23:59:59.000Z

310

Experimental and computational studies of soot emission in a gas fuelled swirl stabilized combustor  

Science Conference Proceedings (OSTI)

The present study is concerned with measuring and simulating soot and flame structure of a non-premixed gas fired swirl stabilized combustor incorporating a two-step soot model. Soot mass fractions have been measured by gravimetric method. Fluent CFD ... Keywords: finite rate model, flamelet model, soot formation

M. Moghiman; T. M. Gruenberger

2002-12-01T23:59:59.000Z

311

DOE Solar Decathlon: Virtual Tours  

NLE Websites -- All DOE Office Websites (Extended Search)

News News Photos Daily Photos Gallery of Houses Virtual Tours Videos Product Directory Village Energy Balance Education Sponsors History FAQs Contacts Virtual Tours Explore the U.S. Department of Energy Solar Decathlon 2013 houses through 360° panoramic images. Select a team from the list below to take a peek inside. Then use your mouse and the controls in the bottom right corner of the tour image to rotate your view. U.S. Department of Energy Solar Decathlon Mobile Search Search Search Help More Search Options Orange County Great Park, Irvine, California, Oct. 3-13, 2013 Photo of a large group of cheering decathletes. They stand at the end of the Solar Decathlon 2013 village and hold a banner that says "U.S. Department of Energy Solar Decathlon." U.S. Department of Energy Solar Decathlon

312

Effects of Soret diffusion on the laminar flame speed and Markstein length of syngas/air mixtures  

E-Print Network (OSTI)

Effects of Soret diffusion on the laminar flame speed and Markstein length of syngas/air mixtures, Beijing 100084, China Abstract The effects of Soret diffusion on premixed syngas/air flames at normal and stretched laminar flame speed and Markstein length of syngas/air mixtures. The laminar flame speed

Chen, Zheng

313

Effects of Soret diffusion on the laminar flame speed and Markstein length of syngas/air mixtures  

E-Print Network (OSTI)

Effects of Soret diffusion on the laminar flame speed and Markstein length of syngas/air mixtures, China Abstract The effects of Soret diffusion on premixed syngas/air flames at normal and elevated and stretched flame speed and Markstein length of syngas/air mixtures. The laminar flame speed and Markstein

Chen, Zheng

314

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

Science Conference Proceedings (OSTI)

An experimental study has been conducted in axisymmetric, co-flowing triple flames with different equivalence ratios of the inner and outer reactant streams (2propane/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)

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

315

NETL: Investigation on Flame Characteristics and Burner Operability Issues  

NLE Websites -- All DOE Office Websites (Extended Search)

Investigation on Flame Characteristics and Burner Operability Issues of Oxy-Fuel Combustion Investigation on Flame Characteristics and Burner Operability Issues of Oxy-Fuel Combustion Project No.: DE-FE0002402 NETL has partnered with the University of Texas at El Paso (UTEP) to investigate the characteristics of oxy-fuel flames and assess their impact on the operability of oxy-fuel combustion systems. The examination of fundamental flame characteristics data and related burner operability parameters are essential for designing and developing oxy-fuel combustion systems for new power plants and retrofitting existing power generation units. In an oxy-fuel system, coal is combusted in an enriched oxygen environment using pure oxygen diluted with recycled CO2 or water vapor (H2O), resulting in a flue stream consisting only of CO2 and H2O (no other co-contaminants) (Figure 1). Oxy-fuel combustion is promising for CCUS applications because water can be condensed out of the CO2/H2O flue stream to produce a relatively pure CO2 end product for capture. Oxy-fuel combustion and subsequent CO2 capture is currently being considered by the DOE's Innovations for Existing Plants Program as having the potential to meet the goal of 90 percent CO2 capture without increasing the cost of electricity more than 35 percent.

316

Research on the Connection between FLAMES and RTI  

Science Conference Proceedings (OSTI)

HLA (High Level Architecture) based distributed simulation has become the mainstream in practice these days. During the development of a HLA federation, the main work is to develop models in each federate. However, it is common that unreasonable models ... Keywords: FLAMES, Model system, RTI, Connection, Client/Server

Xu Xie; Xiaocheng Liu; Kedi Huang

2012-08-01T23:59:59.000Z

317

Multiscalar measurements of turbulence-chemistry interactions in nonpremixed flames  

DOE Green Energy (OSTI)

Selected results from experiments conducted over the past several years involving simultaneous multiscalar point measurements in turbulent nonpremixed flames are reviewed in this paper. In these experiments, spontaneous Raman scattering and Rayleigh scattering measurements of the major species and temperature were combined with laser-induced fluorescence measurements of minor species. The most important feature of these experiments is that they provide detailed data on the instantaneous relationships among species concentration, temperature, and derived scalar quantities that reflect the state of mixing or the progress of reaction. The data allow quantitative comparisons of the thermochemical states in turbulent flames with those in idealized representations, such as steady strained laminar flames, perfectly stirred reactors, or adiabatic equilibrium. The data may also be compared with results (measured or calculated) from unsteady laminar flames and from direct numerical simulations (DNS) of turbulent reacting flows. such comparisons provide insights into the fundamental nature of turbulence-chemistry interactions, and they allow one to examine the validity of some of the basic assumptions that turbulent combustion models are built upon. Furthermore, these data allow quantitative evaluations of the predictive accuracy, strengths, and limitations of a wide variety of combustions models.

Barlow, R.S.

1995-12-01T23:59:59.000Z

318

Modeling of combustion noise spectrum from turbulent premixed flames  

E-Print Network (OSTI)

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

Paris-Sud XI, Université de

319

Formation mechanism for polycyclic aromatic hydrocarbons in methane flames  

E-Print Network (OSTI)

exhausts,7­17 coal-fired, electricity generating power plants,18,19 tobacco smoke,20 residential wood applications including heating systems and gas turbines for electric power generation.62­64 The combustion propane,57,58 butane,59 ethane,31,53,60 and other aliphatic61 flames. Methane is used as fuel in many

Sattler, Klaus

320

Rayleigh temperature profiles in a hydrogen diffusion flame  

DOE Green Energy (OSTI)

Rayleigh scattering from a hydrogen-air laminar jet diffusion flame in combination with a numerical model of the flame has been used to determine temperature profiles. The model predictions of species concentration are used to calculate a mean Rayleigh cross-section which is used to relate the Rayleigh scattered intensity to temperature. Using an argon ion laser producing 7.5 watts at 488 nm and an optical multichannel analyzer (OMA), the scattered light was imaged into a spectrometer. The OMA was rotated 90 degrees to its normal orientation, allowing scans to be taken along the spectrometer exit slit. This resulted in a spatially resolved Rayleigh signal along the laser beam through the entire flame. Spatial resolution of 0.18 mm on each of the 500 detector elements with good signal-to-noise ratios was achieved even with integration times of only 0.03 second. Since the entire profile is made simultaneously, particulate perturbed profiles are easily recognized and discarded. Transverse profiles are presented to show flame structure. Axial profiles are compared to radiation corrected thermocouple measurements.

Smith, J.R.

1978-09-01T23:59:59.000Z

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Flame Synthesis of Carbon Nanotubes Using Low Calorific Value Gases  

DOE Green Energy (OSTI)

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.

Jorge Camacho; Mahesh Subramanya; Ahsan R. Choudhuri

2007-03-31T23:59:59.000Z

322

Radiation intensity of lignite-fired oxy-fuel flames  

SciTech Connect

The radiative heat transfer in oxy-fuel flames is compared to corresponding conditions in air-fuel flames during combustion of lignite in the Chalmers 100 kW oxy-fuel test facility. In the oxy-fuel cases the flue-gas recycle rate was varied, so that, in principle, the same stoichiometry was kept in all cases, whereas the oxygen fraction in the recycled flue-gas mixture ranged from 25 to 29 vol.%. Radial profiles of gas concentration, temperature and total radiation intensity were measured in the furnace. The temperature, and thereby the total radiation intensity of the oxy-fuel flames, increases with decreasing flue-gas recycle rate. The ratio of gas and total radiation intensities increases under oxy-fuel conditions compared to air-firing. However, when radiation overlap between gas and particles is considered the ratios for air-firing and oxy-fuel conditions become more similar, since the gas-particle overlap is increased in the CO{sub 2}-rich atmosphere. A large fraction of the radiation in these lignite flames is emitted by particles whose radiation was not significantly influenced by oxy-fuel operation. Therefore, an increment of gas radiation due to higher CO{sub 2} concentration is not evident because of the background of particle radiation, and, the total radiation intensities are similar during oxy-fuel and air-fuel operation as long as the temperature distributions are similar. (author)

Andersson, Klas; Johansson, Robert; Hjaertstam, Stefan; Johnsson, Filip; Leckner, Bo [Department of Energy and Environment, Division of Energy Technology, Chalmers University of Technology, SE - 412 96 Goeteborg (Sweden)

2008-10-15T23:59:59.000Z

323

Real Time Flame Monitoring of Gasifier and Injectors  

SciTech Connect

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.

Zelepouga, Serguei; Saveliev, Alexei

2011-12-31T23:59:59.000Z

324

Membrane stabilizer  

DOE Patents (OSTI)

A device is provided for stabilizing a flexible membrane secured within a frame, wherein a plurality of elongated arms are disposed radially from a central hub which penetrates the membrane, said arms imposing alternately against opposite sides of the membrane, thus warping and tensioning the membrane into a condition of improved stability. The membrane may be an opaque or translucent sheet or other material. 10 figs.

Mingenbach, W.A.

1988-02-09T23:59:59.000Z

325

Worldwide R&D of Virtual Observatory  

E-Print Network (OSTI)

Virtual Observatory (VO) is a data intensive online astronomical research and education environment, taking advantages of advanced information technologies to achieve seamless and uniform access to astronomical information. The concept of VO was introduced in late of 1990s to meet challenges brought up with data avalanche in astronomy. This paper reviews current status of International Virtual Observatory Alliance, technical highlights from world wide VO projects, and a brief introduction of Chinese Virtual Observatory.

Chenzhou Cui; Yongheng Zhao

2007-11-27T23:59:59.000Z

326

A virtual company concept for reservoir management  

SciTech Connect

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.

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

327

A virtual ad hoc network testbed  

Science Conference Proceedings (OSTI)

Testing of applications for ad hoc networks poses a special technical challenge due to the difficulty of conducting experiments in an ad hoc network environment at a scale larger than a few nodes. One approach is to conduct experiments in a testbed that ... Keywords: MANETs, SITL, VAN, emulation, hybrid testbed, mobile ad hoc networks, mobile networks, network management, shadow nodes, simulation, software-in-, the-loop, virtual ad hoc networks, virtual machines, virtual networks, virtualisation

Alex Poylisher; Constantin Serban; John Lee; Tai-Chuan Lu; Ritu Chadha; Cho-Yu Jason Chiang; Robert Orlando; Kimberly Jakubowski

2010-07-01T23:59:59.000Z

328

Distributed virtual environment scalability and security  

E-Print Network (OSTI)

here. I define a virtual environment (VE) as a computer simulation typically involving space and time. This definitely restricts our examination to computerized systems, where otherwise it could rightly include war simulations going back thousands... in the Manhattan Project to model nuclear detonation, implementing a narrowly scoped, non-real-time virtual environment. In subsequent years computer capacity has grown, and with it the scope and responsiveness of virtual environments. VEs are still used...

Miller, John

2011-11-08T23:59:59.000Z

329

Pipeline Morphing and Virtual Pipelines  

E-Print Network (OSTI)

Pipeline morphing is a simple but effectivetechnique for reconfiguring pipelined FPGA designs at run time. By overlapping computation and reconfiguration, the latency associated with emptying and refilling a pipeline can be avoided. Weshowhow morphing can be applied to linear and mesh pipelines at both word-level and bit-level, and explain how this method can be implemented using Xilinx 6200 FPGAs. We also present an approach using morphing to map a large virtual pipeline onto a small physical pipeline, and the trade-offs involved are discussed.

W. Luk; N. Shirazi; S. R. Guo; P. Y. K. Cheung

1997-01-01T23:59:59.000Z

330

Analysis of the structure and mechanisms of extinction of a counterflow methanol-air diffusion flame  

SciTech Connect

Numerical calculations were performed to determine the structure and to clarify the extinction mechanisms of diffusion flames stabilized between counterflowing streams of methanol and air. The calculations were performed at a value of the thermodynamic pressure equal to 1 atmosphere, with different values for the rate of strain and with two different chemical kinetic mechanisms, mechanism a and mechanism b. Mechanism a and mechanism b have the same set of elementary reactions, but the rate constants for these elementary reactions were obtained from two different references. If mechanism a is used, the authors conclude that at low rates of strain the concentration of CH/sub 2/OH and HCO are in steady state and, if partial equilibrium is assumed for certain reactions, there exist algebraic relations among the concentrations of the radicals OH, H, and O. As the rate of strain is increased, HCO is no longer in steady state and no solution was obtained for a strain rate greater than 521 s/sup -1/. However, if mechanism b is used, the concentration of HCO alone is in steady state, and there also exist algebraic relations among the concentrations of the radicals OH, H, and O. As the rate of strain is increased, no solution was obtained for a strain rate greater than 168 s/sup -1/, and the authors speculate that extinction of the flame is due to a large value of the activation energy for a reaction controlling the pyrolysis of CH/sub 2/OH to CH/sub 2/O.

Seshadri, K.; Trevino, C.; Smooke, M.D.

1989-05-01T23:59:59.000Z

331

Playing the Environment: Games as Virtual Ecologies  

E-Print Network (OSTI)

Playing the Environment: Games as Virtual Ecologies Alendasocial realism, games, environment, ecology 1. INTRODUCTIONversions of the environment? The answer is multifaceted.

Chang, Alenda Y.

2009-01-01T23:59:59.000Z

332

Exploring Genome Rearrangements using Virtual ... - CECM  

E-Print Network (OSTI)

ported extensive transfer of chloroplast DNA to nuclear. DNA [4]. VIRTUAL HYBRIDIZATION. Approximate string matching is defined as identifying, in a text  ...

333

Honors for the Virtual Frog Dissection Kit  

NLE Websites -- All DOE Office Websites (Extended Search)

on Jeopardy in a high school tournament show in November of 1999. Berkeley Lab | ACS | Notice to Users | Whole Frog Project | Virtual Frog Page last modified: 012305...

334

Idaho National Laboratory - Hydropower Program- Virtual Hydropower...  

NLE Websites -- All DOE Office Websites (Extended Search)

The water energy resource and potential project information provided by the Virtual Hydropower Prospector (VHP) is as accurate as possible within the limitations of the...

335

Virtual Hydropower Prospecting – Searching for Hydropower Gold  

DOE Green Energy (OSTI)

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.

Douglas G. Hall

2007-12-01T23:59:59.000Z

336

Architectural Lighting Analysis in Virtual Lighting Laboratory  

NLE Websites -- All DOE Office Websites (Extended Search)

Architectural Lighting Analysis in Virtual Lighting Laboratory NOTICE Due to the current lapse of federal funding, Berkeley Lab websites are accessible, but may not be updated...

337

Virtual Office Community & Computer Lab (VOCC) | ORNL  

NLE Websites -- All DOE Office Websites (Extended Search)

Virtual Office Community and Computer Lab May 30, 2013 CASL's contributing scientist Jin Yan from Westinghouse explains assembly design to DOE Under Secretary for Science, Steven...

338

Individual Virtual Competence and Its Influence on Work Outcomes  

Science Conference Proceedings (OSTI)

Witnessing both opportunities and challenges in virtual work arrangements, researchers have explored a number of technological, social, and organizational factors in order to improve virtual work effectiveness. However, there is limited understanding ... Keywords: Individual Virtual Competence, Individual Work Outcomes, Virtual Organization, Virtual Work

Yinglei Wang; Nicole Haggerty

2011-04-01T23:59:59.000Z

339

Variation of equivalence ratio and element ratios in low-pressure premixed flames of aliphatic fuels  

DOE Green Energy (OSTI)

In previously published work it was found that the element ratios (such as C/O, H/O, H/C) and the equivalence ratio all varied in the flame zone of a low-pressure premixed fuel-rich benzene/oxygen/argon laminar flat flame. These variations were seen from analyses of both the data and detailed kinetic modeling. In the present work, seven additional flames were analyzed in the same manner, including five flames with a single hydrocarbon fuel (methane, acetylene, ethylene, allene, and propene) and two flames with a mixture of fuels (acetylene/allene, hydrogen/allene). All the flames had argon as the diluent, with pressures between 20 and 37.5 Torr, equivalence ratios between 1.6 and 2.5, cold gas velocities between 42 and 126 cm/sec. All of these flames showed variations in the element ratios and equivalence ratios. Furthermore, these variations changed in a consistent pattern with respect to the molecular weight of the fuel. In the flame zone, the percent change in the H/O, C/O and equivalence ratios increased with increasing molecular weight of the fuel, except for the hydrogen/allene flame in which the C/O ratio first increases, then decreases in the flame zone. Also, unlike all the other hydrocarbon flames, the C/O ratio decreases below its inlet value for the methane flame. The H/O and equivalence ratios decrease below their inlet values for the hydrogen/allene flame. These results are explained in terms of differential diffusion effects between the products and the reactants, which increase as the fuel becomes increasingly heavier than the major carbon- and hydrogen-containing products.

C. J. Pope; J. A. Miller

2000-03-14T23:59:59.000Z

340

Partially-Premixed Flames in Internal Combustion Engines  

DOE Green Energy (OSTI)

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

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

2003-11-05T23:59:59.000Z

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Spin Stability  

NLE Websites -- All DOE Office Websites (Extended Search)

Stability Stability of Asymmetrically Charged Plasma Dust I. H. Hutchinson Plasma Science and Fusion Center Massachusetts Institute of Technology, Cambridge, MA, USA Recently it has been reported that, under some circumstances, dust particles sus- pended in the sheath edge are observed to spin [1, 2, 3]. The present paper shows that there is a natural electrostatic mechanism that should cause even perfectly spherical par- ticles in a perfectly irrotational, magnetic-field-free flowing plasma to spin. The stability criterion and the final spin state are obtained[4]. When the particle is made of an insulating material, it can support potential dif- ferences around its surface. In the limit of zero conductivity, and ignoring all charging effects other than electron or ion collection, the surface charge density accumulates in such a way as to bring the local electric current density to zero.

342

Virtualizing office hours in CS 50  

Science Conference Proceedings (OSTI)

In Fall 2007, we introduced "virtual office hours" into Harvard College's introductory computer science course, CS 50, so that students could meet with teaching fellows (TFs) online to discuss problem sets at any hour from anywhere. Our goals were to ... Keywords: CSCW, collaboration, distance education, virtual office hours

David J. Malan

2009-07-01T23:59:59.000Z

343

Enabling scientific workflows in virtual reality  

Science Conference Proceedings (OSTI)

To advance research and improve the scientific return on data collection and interpretation efforts in the geosciences, we have developed methods of interactive visualization, with a special focus on immersive virtual reality (VR) environments. Earth ... Keywords: geosciences, scientific visualization, virtual reality, workflow

Oliver Kreylos; Gerald Bawden; Tony Bernardin; Magali I. Billen; Eric S. Cowgill; Ryan D. Gold; Bernd Hamann; Margarete Jadamec; Louise H. Kellogg; Oliver G. Staadt; Dawn Y. Sumner

2006-06-01T23:59:59.000Z

344

Formalizing the evolution of virtual communities  

Science Conference Proceedings (OSTI)

Collaboration increasingly takes place in virtual communities using the Internet. These communities are socio-technical systems that tend to evolve strongly and become more complex over time. To ensure that the changes to these complex socio-technical ... Keywords: Conversations for specification, Specification process model, Theory of communicative action, Virtual communities

Aldo de Moor; Hans Weigand

2007-04-01T23:59:59.000Z

345

EMMA: an adaptive display for virtual therapy  

Science Conference Proceedings (OSTI)

Environments used up to now for therapeutic applications are invariable ones. Their contents can not be changed neither by the therapist nor by the patient. However, this is a technical issue that can be solved with current technology. In this paper, ... Keywords: adaptive display, virtual reality, virtual therapy

Mariano Alcañiz; Cristina Botella; Beatriz Rey; Rosa Baños; Jose A. Lozano; Nuria Lasso de la Vega; Diana Castilla; Javier Montesa; Antonio Hospitaler

2007-07-01T23:59:59.000Z

346

High availability using virtualization - 3RC  

E-Print Network (OSTI)

High availability has always been one of the main problems for a data center. Till now high availability was achieved by host per host redundancy, a highly expensive method in terms of hardware and human costs. A new approach to the problem can be offered by virtualization. Using virtualization, it is possible to achieve a redundancy system for all the services running on a data center. This new approach to high availability allows the running virtual machines to be distributed over a small number of servers, by exploiting the features of the virtualization layer: start, stop and move virtual machines between physical hosts. The 3RC system is based on a finite state machine, providing the possibility to restart each virtual machine over any physical host, or reinstall it from scratch. A complete infrastructure has been developed to install operating system and middleware in a few minutes. To virtualize the main servers of a data center, a new procedure has been developed to migrate physical to virtual hosts. ...

Calzolari, Federico; Ciampa, Alberto; Mazzoni, Enrico; Domenici, Andrea; Vaglini, Gigliola; 10.1088/1742-6596/219/5/052017

2012-01-01T23:59:59.000Z

347

Virtual screening on large scale grids  

Science Conference Proceedings (OSTI)

Large scale grids for in silico drug discovery open opportunities of particular interest to neglected and emerging diseases. In 2005 and 2006, we have been able to deploy large scale virtual docking within the framework of the WISDOM initiative against ... Keywords: Avian influenza, Large scale grids, Malaria, Virtual screening

Nicolas Jacq; Vincent Breton; Hsin-Yen Chen; Li-Yung Ho; Martin Hofmann; Vinod Kasam; Hurng-Chun Lee; Yannick Legré; Simon C. Lin; Astrid Maaí; Emmanuel Medernach; Ivan Merelli; Luciano Milanesi; Giulio Rastelli; Matthieu Reichstadt; Jean Salzemann; Horst Schwichtenberg; Ying-Ta Wu; Marc Zimmermann

2007-05-01T23:59:59.000Z

348

Grid-enabled high throughput virtual screening  

Science Conference Proceedings (OSTI)

Large scale grids for in silico drug discovery open opportunities of particular interest to neglected and emerging diseases. In 2005 and 2006, we have been able to deploy large scale virtual docking within the framework of the WISDOM initiative against ... Keywords: avian influenza, large scale grids, malaria, virtual screening

Nicolas Jacq; Vincent Breton; Hsin-Yen Chen; Li-Yung Ho; Martin Hofmann; Hurng-Chun Lee; Yannick Legré; Simon C. Lin; Astrid Maaß; Emmanuel Medernach; Ivan Merelli; Luciano Milanesi; Giulio Rastelli; Matthieu Reichstadt; Jean Salzemann; Horst Schwichtenberg; Mahendrakar Sridhar; Vinod Kasam; Ying-Ta Wu; Marc Zimmermann

2007-01-01T23:59:59.000Z

349

A logic approach to virtual sensor networks  

Science Conference Proceedings (OSTI)

This paper presents a technique that builds a layer of virtual sensors over a sensor network. The virtual sensors are able to infer and provide data for the physical sensors that do not work. The key assumption of our approach is that the physical quantities ...

Luciano Caroprese; Carmela Comito; Domenico Talia; Ester Zumpano

2010-08-01T23:59:59.000Z

350

Research on virtual assembly of supercritical boiler  

Science Conference Proceedings (OSTI)

Supercritical boiler is an important measure to solve problems like electricity shortage or energy intensity, with its high combustion efficiency. As supercritical boiler is a large and complex product, it may appear some problems of collision, location ... Keywords: interaction, lightweight model, supercritical boiler, virtools, virtual assembly, virtual reality

Pi-Guang Wei; Wen-Hua Zhu; Hao Zhou

2010-09-01T23:59:59.000Z

351

Evolutionary virtual agent at an exhibition  

Science Conference Proceedings (OSTI)

This paper describes the Evolutionary Virtual Agent (EVA) prototype designed as an interactive entertainment system for a multimedia exhibition. This implementation uses a behavioral engine based on a dynamical subsumption architecture and a 3D animated ... Keywords: conversational character, intelligent agent, physical model, virtual creature

Jean-Claude Heudin

2007-09-01T23:59:59.000Z

352

Performance implications of virtualizing multicore cluster machines  

Science Conference Proceedings (OSTI)

High performance computers are typified by cluster machines constructed from multicore nodes and using high performance interconnects like Infiniband. Virtualizing such 'capacity computing' platforms implies the shared use of not only the nodes and node ... Keywords: Infiniband, high-performance computing, virtualization

Adit Ranadive; Mukil Kesavan; Ada Gavrilovska; Karsten Schwan

2008-03-01T23:59:59.000Z

353

Security and trust in virtual healthcare communities  

Science Conference Proceedings (OSTI)

The main purpose of a virtual healthcare community is to enforce members' collaboration and allow them collectively conduct health care activities. Patient monitoring and medical consultation and support are the most popular activities inside health ... Keywords: health care, security, teleconsultation, trust, virtual communities

Anargyros Chryssanthou; Iraklis Varlamis; Charikleia Latsiou

2009-06-01T23:59:59.000Z

354

Real Time Flame Monitoring of Gasifier Burner and Injectors  

NLE Websites -- All DOE Office Websites (Extended Search)

8 8 Gasification Technologies contacts Gary J. stiegel Gasification Technology Manager National Energy Technology Laboratory 626 Cochrans Mill Road P.O. Box 10940 Pittsburgh, PA 15236 412-386-4499 gary.stiegel@netl.doe.gov Jenny tennant Project Manager National Energy Technology Laboratory 3610 Collins Ferry Road P.O. Box 880 Morgantown, WV 26507 304-285-4830 jenny.tennant@netl.doe.gov David Rue Principal Investigator Gas Technology Institute 1700 South Mount Prospect Road Des Plaines, IL 60018 847-768-0508 david.rue@gastechnology.org Real Time Flame moniToRing oF gasiFieR BuRneR and injecToRs Description Combustion scientists and engineers have studied radiant emissions of various flames for many years. For some time, technologists have understood the rich potential for

355

Effect of the Darrieus-Landau instability on turbulent flame velocity  

E-Print Network (OSTI)

Propagation of turbulent premixed flames influenced by the intrinsic hydrodynamic flame instability (the Darrieus-Landau instability) is considered in a two-dimensional case using the model nonlinear equation proposed recently. The nonlinear equation takes into account both influence of external turbulence and intrinsic properties of a flame front, such as small but finite flame thickness and realistically large density variations across the flame front. Dependence of the flame velocity on the turbulent length scale, on the turbulent intensity and on the density variations is investigated in the case of weak non-linearity and weak external turbulence. It is shown that the Darrieus-Landau instability influences the flamelet velocity considerably. The obtained results are in agreement with experimental data on turbulent burning of moderate values of the Reynolds number.

Maxim Zaytsev; Vitaliy Bychkov

2012-11-26T23:59:59.000Z

356

Manufacturing cost of flame heated thermionic converters. Topical report  

DOE Green Energy (OSTI)

The cost of thermionic converters has been estimated in support of the cost calculations for thermionic topping of central station powerplants. These calculations supersede the previous calculations made in 1975 and use a design concept similar to the current configuration of flame-heated converters. The cost of converters was estimated by obtaining quotations from manufactureres whenever possible. The selling cost was found to be $110 per kilowatt.

LaRue, G.; Miskolczy, G.

1979-04-01T23:59:59.000Z

357

Noise in non?premixed turbulent syngas flames  

Science Conference Proceedings (OSTI)

A turbulentsyngasflame may generateacoustic noise of high acoustic intensity in a combustion chamber. This may lead to the failure of construction components in a gas turbine engine in periods of the order of 1–100 hours. The research as described in the literature has almost exclusively been performed on the generation of noise in premixed methane or propane flames.Syngas fuel is a mixture of hydrogen and carbon monoxide

Sikke A. Klein; Jim B. W. Kok

1998-01-01T23:59:59.000Z

358

The Flame Doctor® Combustion Diagnostic System: Beta Test Program  

Science Conference Proceedings (OSTI)

Accurate knowledge of individual burner flame quality is essential to advanced boiler management. This is particularly important for advanced low-NOx burners, which are more sensitive to changes in operation and fuel quality than conventional burners. While global emissions monitoring is certainly important for boiler control, such monitoring can only provide information that has been averaged over many burners and long time scales. Because individual burners can exhibit large differences in emissions an...

2004-11-24T23:59:59.000Z

359

RADIATIVE PROPERTY MEASUREMENTS OF OXY-FUEL FLAMES  

Science Conference Proceedings (OSTI)

As part of the DOE Existing Plants, Emissions and Capture (EPEC) program, oxy-combustion is being investigated as a method to simplify carbon capture and reduce the parasitic energy penalties associated with separating CO2 from a dilute flue gas. Gas-phase radiation heat transfer in boilers becomes significant when shifting from air-firing to oxycombustion, and must be accurately represented in models. Currently, radiative property data are not widely available in the literature for conditions appropriate to this environment. In order to facilitate the development and validation of accurate oxy-combustion models, NETL conducted a series of studies to measure radiation properties of oxy-fuel flames at adiabatic flame temperatures of 1750 - 1950K, and product molar concentrations ranging from 95% CO2 to 100% steam, determined by equilibrium calculations. Transmission coefficients were measured as a function of wavelength using a mid-IR imaging spectrometer and a blackbody radiation source. Additionally, flame temperatures were calculated using data collected within CO2 and H2O absorption bands. Experimental results were compared to two statistical narrowband models and experimental data from literature sources. These comparisons showed good overall agreement, although differences between the models and experimental results were noted, particularly for the R branch of the 2.7 ?m H2O band.

Clinton R. Bedick; Stephen K. Beer; Kent H. Casleton; Benjamin T. Chorpening; David W. Shaw; M. Joseph Yip

2011-03-01T23:59:59.000Z

360

Fuel control for gas turbine with continuous pilot flame  

SciTech Connect

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.

Swick, Robert M. (Indianapolis, IN)

1983-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Computational and experimental study of laminar flames. Progress report, September 1, 1990--October 31, 1991  

SciTech Connect

During fiscal year 1991 we have made substantial progress in both the computational and experimental portions of our research. In particular we have continued our study of non-premixed axisymmetric methane-air flames. Computer calculations of multidimensional elliptic flames with two carbon atom chemistry using a shared memory parallel computer are reported for the first time. Also laser spectroscopy of flames utilizing a neodymium laser are also reported. (GHH)

Smooke, M.; Long, M.

1991-12-31T23:59:59.000Z

362

T-608: HP Virtual Server Environment Lets Remote Authenticated...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

8: HP Virtual Server Environment Lets Remote Authenticated Users Gain Elevated Privileges T-608: HP Virtual Server Environment Lets Remote Authenticated Users Gain Elevated...

363

The Virtual Gas Turbine System for Alloy Assesment  

Science Conference Proceedings (OSTI)

Key words: Virtual turbine, Alloy design program, Gas turbine design program, Nickel-base ... developed a virtual gas turbine (VT) system as a combination of.

364

OLADE Virtual Energy Training Program (CAPEV) | Open Energy Informatio...  

Open Energy Info (EERE)

Search Page Edit with form History Facebook icon Twitter icon OLADE Virtual Energy Training Program (CAPEV) Jump to: navigation, search Tool Summary Name: OLADE Virtual Energy...

365

Inhibition ofPremixed Methane-Air Flames by Water Mist  

Science Conference Proceedings (OSTI)

Fuss, SP, Dye, DJ, Williams, BA, and Fleming, JW, "Inhibition of Premixed Methane-Air Flames by Water Mist," Proceedings of the Fall Technical ...

2013-10-29T23:59:59.000Z

366

Self-induced unstable behaviors of CH4 and H2/CH4 flames in a...  

NLE Websites -- All DOE Office Websites (Extended Search)

Portillo, David Littlejohn, Scott M. Martin, and Robert K. Cheng Journal Combustion and Flame Volume 160 Issue 2 Pagination 307 - 321 Date Published 022013 ISSN 00102180 DOI...

367

A model for the (QUASI) steady flame spread on vertical and horizontal surface.  

E-Print Network (OSTI)

??Initial fire spread is composed of the processes of ignition, flame spread, and burning rate. The effects of a material's thermal characteristics and burning behaviors… (more)

Shi, Yan

2008-01-01T23:59:59.000Z

368

Numerical Simulation of Flame-Vortex Interactions in Natural and Synthetic Gas Mixtures .  

E-Print Network (OSTI)

??The interactions between laminar premixed flames and counter-rotating vortex pairs in natural and synthetic gas mixtures have been computationally investigated through the use of Direct… (more)

Weiler, Justin D.

2004-01-01T23:59:59.000Z

369

Flame retardant finishing for cotton using a hydroxy-functional organophosphorus oligomer.  

E-Print Network (OSTI)

??New durable flame retardant finishing systems based on a hydroxy-functional organophosphorus oligomer (HFPO) and a bonding agent have been developed for cotton. In this research,… (more)

Wu, Weidong

2004-01-01T23:59:59.000Z

370

An integral model for turbulent flame radial lengths under a ceiling.  

E-Print Network (OSTI)

?? An analytical study using an integral model for turbulent flame radial lengths under a ceiling is presented. Dimensionless equations give results in terms of… (more)

Ding, Haiwen

2010-01-01T23:59:59.000Z

371

Optimization of Global Reaction Mechanisms Evaluated on The Sandia Flame D.  

E-Print Network (OSTI)

??The main goal is to develop and evaluate global reaction mechanisms. The optimization is done using two methods; Laminar Flame Speed and Perfectly Stirred Reactor.… (more)

Mohseni, Seyedmohammad

2012-01-01T23:59:59.000Z

372

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

SciTech Connect

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.

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

2013-08-20T23:59:59.000Z

373

Oxy-coal combustion: stability of coaxial pulverized coal flames in O2/CO2 environments.  

E-Print Network (OSTI)

??Oxy-coal combustion, in which air is replaced by an O2/ CO2 mixture, is one of the few technologies that may allow CO2 capture and sequestration… (more)

Zhang, Jingwei

2010-01-01T23:59:59.000Z

374

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

E-Print Network (OSTI)

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 ...

Shroll, Andrew Philip

2011-01-01T23:59:59.000Z

375

Experimental investigation into the effect of reformer gas addition on flame speed and flame front propagation in premixed, homogeneous charge gasoline engines  

SciTech Connect

The effect of reformer gas addition to gasoline in internal combustion engines is assessed based on in-cylinder measurement techniques. These include ion sensors, an optical spark plug and heat release analysis from the cylinder pressure. A detailed analysis of these measurements is presented, giving insight into the combustion process and into the energy release. The flame front shape and propagation in the combustion chamber are reconstructed and the flame speed is estimated. The laminar flame speed has been observed to increase linearly with the energy fraction of reformer gas in the fuel blend. From pure gasoline to pure reformer gas the laminar flame speed increases by a factor of 4.4. The relative increase in the turbulent flame speed is lower. These results confirm what can be observed from the heat release analysis, that reformer gas addition mainly shortens the first phase of the combustion process. Different reformer gas compositions were tested, varying the ratio of hydrogen to inert species. Finally, flame propagation and flame speed at EGR-burn limit and at lean-burn limit are investigated. (author)

Conte, Enrico; Boulouchos, Konstantinos [Aerothermochemistry and Combustion Systems Laboratory (LAV), ETH Zurich, CH-8092 (Switzerland)

2006-07-15T23:59:59.000Z

376

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  

Science Conference Proceedings (OSTI)

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)

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

377

Effects of Combustor Geometry on the Flowfields and Flame Properties of A  

NLE Websites -- All DOE Office Websites (Extended Search)

Effects of Combustor Geometry on the Flowfields and Flame Properties of A Effects of Combustor Geometry on the Flowfields and Flame Properties of A Low-Swirl Injector Title Effects of Combustor Geometry on the Flowfields and Flame Properties of A Low-Swirl Injector Publication Type Journal Article Year of Publication 2008 Authors Cheng, Robert K., and David Littlejohn Journal Proceedings of the Combustion Institute Type of Article Conference Paper Abstract The Low-swirl injector (LSI) is a novel dry-low NOx combustion method that is being developed for gas turbines to burn a variety of gaseous fuels including natural gas, low-Btu fuels, syngases and hydrogen. Its basic principle is described by a top level analytical model that relates the flame position to the flowfield similarity parameters and the turbulent flame speed correlation. The model was based on experimental measurements in open laboratory flames. It has been useful for guiding hardware development. As the LSI is being adapted to different engine configurations, one open question is how the combustor geometry and size affect its basic operating principle. The objective of this paper is to investigate these effects by conducting Particle Image Velocimetry (PIV) measurements in open and enclosed flames produced by a 6.35 cm diameter LSI using two quartz cylinders of 15.5 and 20 cm diameter to simulate the combustor casing. Results from 18 methane-air flames show that the enclosures do not alter the flame properties or the nearfield flow structures. The differences occur mostly in the farfield where the tighter enclosure deters the formation of a weak recirculation zone. The enclosure effects on hydrogen and hydrogen-methane flames were studies using the 20 cm cylinder. The results show that the outer recirculation zone generated at the corner of the dump plane promotes the formation of attached flames. However, the properties and nearfield flow features of the attached flames are similar to those of the lifted flames. At higher stoichiometries, the attached flame collapses to form a compact disc shaped flame that has very different flowfield structures. These results show that the enclosure effects on the LSI are strongly coupled to the fuel type and dump plane geometry but are less dependent on the enclosure size. These observations will provide the basis for developing computational methods that can be used as design tools for LSI adaptation

378

Shared control architectures for haptic training: Performance and coupled stability analysis  

Science Conference Proceedings (OSTI)

A novel shared control architecture is presented for dual-user haptic training simulation systems for enhanced interaction between the users and between each user and the virtual environment. The coupled stability of the proposed control architecture ... Keywords: Dual-user haptic training, Llewellyn's criterion, kinesthetic performance, multilateral control, task performance, transparency, unconditional stability

Behzad Khademian; Keyvan Hashtrudi-Zaad

2011-11-01T23:59:59.000Z

379

Virtual CSU-CHILL Radar: The VCHILL  

Science Conference Proceedings (OSTI)

The Virtual CHILL (VCHILL) system makes it possible to transfer the educational and research experience of the Colorado State University dual polarization radar to remote locations over the Internet. The VCHILL operation includes remote control ...

V. Chandrasekar; Yoong-Goog Cho; D. Brunkow; A. Jayasumana

2005-07-01T23:59:59.000Z

380

DOE Virtual University | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Services » Learning & Development » DOE Virtual University Services » Learning & Development » DOE Virtual University DOE Virtual University Learn more about DVU The Department of Energy Virtual University (DVU) is a central venue for executing, managing, partnering, and sharing corporate learning activities and programs. Read more Training Resources The Training Resources webpage has the links to the commonly used course catalogs and course schedules used by DOE employees. Course registration links can also be found here. Read more College of Science The College of Science's (CS) mission is to provide DOE employees with the information resources necessary to keep current in the field of science. Read more College of Health Safety & Security Through the National Training Center (NTC), the Office of Health, Safety

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Robotics virtual rail system and method  

SciTech Connect

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.

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

2011-07-05T23:59:59.000Z

382

Occlusion Culling in Large Virtual Environments  

Science Conference Proceedings (OSTI)

In this paper, occlusion testing in very large virtual environments is discussed from two perspectives: a theoretical one, discussing occlusion culling in relation to detail elision (level of detail), and a practical one, relating to an adaptive occlusion-culling ...

Karsten Bormann

2001-10-01T23:59:59.000Z

383

Trust negotiation: authorization for virtual organizations  

Science Conference Proceedings (OSTI)

Trust negotiation is an authorization approach for open distributed systems, such as dynamic coalitions and other types of virtual organizations. Under the trust negotiation approach to authorization, every resource that might be shared within the coalition ...

M. Winslett; Adam J. Lee; Kenneth J. Perano

2009-04-01T23:59:59.000Z

384

Pragmatic Lighting Transition Design for Virtual Environments  

Science Conference Proceedings (OSTI)

This abstract describes and motivates Ideel, a tool to explore expression of high-level lighting design changes for interactive virtual environments. Ideel allows lighting designers to quickly describe lighting changes using a sketchbased interface.

Joshua B. Gross

2006-09-01T23:59:59.000Z

385

Stakeholder collaboration and engagement in virtual projects  

Science Conference Proceedings (OSTI)

Stakeholder management is an important and common practice in any project, as it allows managers to better manage process, performance and risk. In virtual projects, collaboration and engagement with stakeholders is relatively more complex, challenging, ...

Ofer Zwikael; Arun A. Elias; Mark J. Ahn

2012-03-01T23:59:59.000Z

386

Virtualisation: Real security for virtual machines  

Science Conference Proceedings (OSTI)

Server virtualisation offers many real benefits to enterprises, maximising hardware resources and providing significant cost and energy savings. But there is a downside: all of the security issues we battle on networked systems also plague virtual machines, ...

Ulf Mattsson

2009-04-01T23:59:59.000Z

387

Applied Virtual Intelligence in Oil & Gas Industry;  

E-Print Network (OSTI)

1 Applied Virtual Intelligence in Oil & Gas Industry; Past, Present, & Future Shahab D. Mohaghegh on a daily basis by almost everyone. Credit Card Fraud Detection Bank Loan Approval Bomb Sniffing Devices

Mohaghegh, Shahab

388

Dynamic Rightsizing with Quality-Controlled Algorithms in Virtualization Environments  

Science Conference Proceedings (OSTI)

Virtualization and partitioning are the means by which multiple application instances can share and run multiple virtual machines supported by a platform. In a Green Cloud environment, the goal is to consolidate multiple applications onto virtual machines ... Keywords: Cloud Computing, Energy-Saving, Green Cloud, Queuing, Theory Virtual Machine

Ming-Jeng Yang; Chin-Lin Kuo; Yao-Ming Yeh

2011-04-01T23:59:59.000Z

389

Virtual 94th AOCS Annual Meeting and Expo  

Science Conference Proceedings (OSTI)

AOCS has created the first Virtual AOCS Annual Meeting & Expo on CD-ROM. Virtual 94th AOCS Annual Meeting and Expo Virtual Meetings DVD & CD-ROMs AOCS has created the first Virtual AOCS Annual Meeting & Expo on CD-ROM.  bstracts for ev

390

Improving energy efficiency of buffer cache in virtual machines  

Science Conference Proceedings (OSTI)

Main memory contributes a large fraction of energy consumption in powerful servers running virtualization software to support concurrent virtual machines (VMs). Furthermore, data-intensive applications executing inside virtual machines increase the demand ... Keywords: Buffer Cache,Virtual Machine,Energy Management

Lei Ye; Chris Gniady

2012-06-01T23:59:59.000Z

391

A semantics driven user interface for virtual saarlouis  

Science Conference Proceedings (OSTI)

Virtual reality can support edutainment applications which seek to provide an engaging experience with virtual objects and spaces. However, these environments often contain scripted avatars and activities that lack the ability to respond or adapt to ... Keywords: ISReal, agents, semantic virtual worlds, virtual saarlouis

Deborah Richards; Stefan Warwas

2012-09-01T23:59:59.000Z

392

Applications of virtual reality for visually impaired people  

Science Conference Proceedings (OSTI)

This paper describes in detail the development and applications of a Virtual Reality Simulator for Visually Impaired People. It makes an auditory representation of the virtual environment, rendering the virtual world entirely through the hearing. The ... Keywords: electromagnetic position tracker, spatial sound, virtual reality, visually impaired

M. A. Torres-Gil; O. Casanova-Gonzalez; J. L. Gonzalez-Mora

2010-02-01T23:59:59.000Z

393

Past Project on Visualization and Virtual Reality for ...  

Science Conference Proceedings (OSTI)

NAME: Visualization and Virtual Reality for Manufacturing CONTACT: Sandy Ressler, sandy.ressler@nist.gov IMPETUS ...

394

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

DOE Green Energy (OSTI)

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

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

2007-10-01T23:59:59.000Z

395

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

E-Print Network (OSTI)

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

Dandy, David

396

Laboratory Study of Premixed H2-Air and H2-N2-Air Flames in a...  

NLE Websites -- All DOE Office Websites (Extended Search)

of Premixed H2-Air and H2-N2-Air Flames in a Low-Swirl Injector for Ultra-Low Emissions Gas Turbines Title Laboratory Study of Premixed H2-Air and H2-N2-Air Flames in a Low-Swirl...

397

Molecular diffusion effects in LES of a piloted methaneair flame Konstantin A. Kemenov  

E-Print Network (OSTI)

Molecular diffusion effects in LES of a piloted methane­air flame Konstantin A. Kemenov , Stephen-premixed turbulent combustion Large-eddy simulation Molecular diffusion Sandia flame D a b s t r a c t Molecular splines relationships are employed to represent thermochemical variables. The role of molecular

Pope, Stephen B.

398

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

E-Print Network (OSTI)

in a laminar premixed n-butane flame", Combustion and Flame,1.5 atm; T=1431-1680 K; (b) n-butane [22], ?=1.0; 2.5% C 4 Hof the parameters for n- butane were obtained from Marinov

Saxena, Priyank

2007-01-01T23:59:59.000Z

399

2008 Special Issue: An adaptive method for industrial hydrocarbon flame detection  

Science Conference Proceedings (OSTI)

An adaptive method for an infrared (IR) hydrocarbon flame detection system is presented. The model makes use of joint time-frequency analysis (JTFA) for feature extraction and the artificial neural networks (ANN) for training and classification. Multiple ... Keywords: Artificial neural networks, Flame detection, Signal processing

Javid J. Huseynov; Shankar B. Baliga; Alan Widmer; Zvi Boger

2008-03-01T23:59:59.000Z

400

Global NOx Measurements in Turbulent Nitrogen-Diluted Hydrogen Jet Flames  

DOE Green Energy (OSTI)

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

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

2007-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Imaging and Diagnostics of Turbulent Methane-Air Premixed Flames by Acetone-OH Simultaneous PLIF  

Science Conference Proceedings (OSTI)

A strategy of diagnostics of ultra-lean combustion based on acetone-OH simultaneous PLIF is presented. Acetone seeded in the fuel flow and combustion-generated OH work for a marker of "unburned" and "burnt" zones, respectively. Since acetone and OH does ... Keywords: Acetone, Flame imaging, OH, PLIF, Turbulent flame

Y. Nakamura; S. Manome; H. Yamashita

2008-01-01T23:59:59.000Z

402

The dependence of chemistry on the inlet equivalence ratio in vortex-flame interactions [Printed LBNL report with title: The effect of stoichiometry on vortex flame interactions  

E-Print Network (OSTI)

premixed flames," Sandia N a t i o n a l Laboratories Reporttransport properties," Sandia N a t i o n a l LaboratoriesU C Berkeley, Berkeley, C A Sandia National Laboratories,

Tonse, Shaheen R.

2011-01-01T23:59:59.000Z

403

The dependence of chemistry on the inlet equivalence ratio in vortex-flame interactions [Printed LBNL report with title: The effect of stoichiometry on vortex flame interactions  

E-Print Network (OSTI)

premixed flames," Sandia N a t i o n a l Laboratories Reporttransport properties," Sandia N a t i o n a l LaboratoriesU C Berkeley, Berkeley, C A Sandia National Laboratories,

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

1999-01-01T23:59:59.000Z

404

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

E-Print Network (OSTI)

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

Geddes, Cameron Guy Robinson

405

Effects of Soret diffusion on the laminar flame speed and Markstein length of syngas/air mixtures  

E-Print Network (OSTI)

Effects of Soret diffusion on the laminar flame speed and Markstein length of syngas/air mixtures syngas/air flames at normal and elevated temperatures and pressures are investigated numerically of syngas/air mixtures. The laminar flame speed and Markstein length are obtained by simulating

Chen, Zheng

406

Critical radius for sustained propagation of spark-ignited spherical flames  

Science Conference Proceedings (OSTI)

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

Kelley, Andrew P.; Jomaas, Grunde; Law, Chung K. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States)

2009-05-15T23:59:59.000Z

407

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

Science Conference Proceedings (OSTI)

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

Consul, R.; Oliva, A.; Perez-Segarra, C.D.; Carbonell, D. [Centre Tecnologic de Transferencia de Calor (CTTC), Universitat Politecnica de Catalunya (UPC), Colom 11, E-08222, Terrassa, Barcelona (Spain); de Goey, L.P.H. [Eindhoven University of Technology, Department of Mechanical Engineering, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

2008-04-15T23:59:59.000Z

408

New flamelet combustion model combining premixed and non-premixed turbulent flames  

SciTech Connect

Flamelet models are now used in many turbulent combustion studies. The reaction zone is described as a collection of laminar flame elements imbedded in the turbulent flow. This approach decouples the detailed modeling of chemistry features of flamelets from the computation of the entire flow field. Most flamelet models consider only premixed or nonpremixed flame elements. But, in some situations, such as ignition of a diffusion flame or combustion in a Diesel engine, premixed and nonpremixed flames may be present in the same flow. The aim of the study is to propose a description, extending the basic ideas of the coherent flame model of Marble and Broadwell (1977) including premixed and nonpremixed flamelets. 19 references.

Veynante, D.; Lacas, F.; Candel, S.M.

1989-01-01T23:59:59.000Z

409

STABILIZED OSCILLATOR  

DOE Patents (OSTI)

This patent relates to sine-wave generators and in particular describes a generator with a novel feedback circuit resulting in improved frequency stability. The generator comprises two triodes having a common cathode circuit connected to oscillate at a frequency and amplitude at which the loop galn of the circutt ls unity, and another pair of triodes having a common cathode circuit arranged as a conventional amplifier. A signal is conducted from the osciliator through a frequency selective network to the amplifier and fed back to the osciliator. The unique feature of the feedback circuit is the amplifier operates in the nonlinear portion of its tube characteristics thereby providing a relatively constant feedback voltage to the oscillator irrespective of the amplitude of its input signal.

Jessen, P.L.; Price, H.J.

1958-03-18T23:59:59.000Z

410

A model of particle nucleation in premixed ethylene flames  

SciTech Connect

A detailed model of particle inception is proposed to delve into the physical structure and chemistry of combustion-formed particles. A sectional method is used, from a previously developed kinetic mechanism of particle formation with a double discretization of the particle phase in terms of C and H atom number. The present model also distinguishes between different particle structures based on their state of aggregation; single high molecular mass molecules, cluster of molecules and aggregates of clusters. The model predicts the mass of particles, hydrogen content and internal structure. It represents a first approach in following the chemical evolution and internal structure of the particles formed in flames, coupled with the main pyrolysis and oxidation of the fuel. The model is tested in atmospheric premixed flat flames of ethylene and the effect of fuel equivalence ratio on particle morphology is analyzed. Molecular weight growth of aromatic compounds and the inception of particles are predicted. The morphology of the particles and the number of molecules in the clusters at particle inception are also indicated. (author)

D'Anna, Andrea; Sirignano, Mariano [Dipartimento di Ingegneria Chimica, Universita di Napoli ''Federico II'', Napoli (Italy); Kent, John [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney (Australia)

2010-11-15T23:59:59.000Z

411

Adaptive low Mach number simulations of nuclear flame microphysics  

SciTech Connect

We introduce a numerical model for the simulation of nuclear flames in Type Ia supernovae. This model is based on a low Mach number formulation that analytically removes acoustic wave propagation while retaining the compressibility effects resulting from nuclear burning. The formulation presented here generalizes low Mach number models used in combustion that are based on an ideal gas approximation to the arbitrary equations of state such as those describing the degenerate matter found in stellar material. The low Mach number formulation permits time steps that are controlled by the advective time scales resulting in a substantial improvement in computational efficiency compared to a compressible formulation. We briefly discuss the basic discretization methodology for the low Mach number equations and their implementation in an adaptive projection framework. We present validation computations in which the computational results from the low Mach number model are compared to a compressible code and present an application of the methodology to the Landau-Darrieus instability of a carbon flame.

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

2003-03-20T23:59:59.000Z

412

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

DOE Green Energy (OSTI)

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.

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

413

Effects of flow transients on the burning velocity of hydrogen-air premixed flames  

DOE Green Energy (OSTI)

The effects of unsteady strain rate on the burning velocity of hydrogen-air premixed flames are studied in an opposed nozzle configuration. The numerical method employs adaptive time integration of a system of differential-algebraic equations. Detailed hydrogen-air kinetic mechanism and transport properties are considered. The equivalence ratio is varied from lean to rich premixtures in order to change the effective Lewis number. Steady Markstein numbers for small strain rate are computed and compared with experiment. Different definitions of flame burning velocity are examined under steady and unsteady flow conditions. It is found that, as the unsteady frequency increases, large deviations between different flame speeds are noted depending on the location of the flame speed evaluation. Unsteady flame response is investigated in terms of the Markstein transfer function which depends on the frequency of oscillation. In most cases, the flame speed variation attenuates at higher frequencies, as the unsteady frequency becomes comparable to the inverse of the characteristic flame time. Furthermore, unique resonance-like behavior is observed for a range of rich mixture conditions, consistent with previous studies with linearized theory.

H. G. Im; J. H. Chen

2000-07-30T23:59:59.000Z

414

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

Science Conference Proceedings (OSTI)

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

Sharma, Sandeep; Harper, Michael R.; Green, William H. [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

2010-07-15T23:59:59.000Z

415

Three-dimensional numerical simulations of Rayleigh-Taylorunstable flames in type Ia supernovae  

SciTech Connect

Flame instabilities play a dominant role in accelerating the burning front to a large fraction of the speed of sound in a Type Ia supernova. We present a three-dimensional numerical simulation of a Rayleigh-Taylor unstable carbon flame, following its evolution through the transition to turbulence. A low Mach number hydrodynamics method is used, freeing us from the harsh time step restrictions imposed by sound waves. We fully resolve the thermal structure of the flame and its reaction zone, eliminating the need for a flame model. A single density is considered, 1.5x107 gm/cc, and half carbon/half oxygen fuel--conditions under which the flame propagated in the flamelet regime in our related two-dimensional study. We compare to a corresponding two-dimensional simulation, and show that while fire-polishing keeps the small features suppressed in two dimensions, turbulence wrinkles the flame on far smaller scales in the three-dimensional case, suggesting that the transition to the distributed burning regime occurs at higher densities in three dimensions. Detailed turbulence diagnostics are provided. We show that the turbulence follows a Kolmogorov spectrum and is highly anisotropic on the large scales, with a much larger integral scale in the direction of gravity. Furthermore, we demonstrate that it becomes more isotropic as it cascades down to small scales. Based on the turbulent statistics and the flame properties of our simulation, we compute the Gibson scale. We show the progress of the turbulent flame through a classic combustion regime diagram, indicating that the flame just enters the distributed burning regime near the end of our simulation.

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

2005-01-28T23:59:59.000Z

416

Architectural Lighting Analysis in Virtual Lighting Laboratory  

NLE Websites -- All DOE Office Websites (Extended Search)

Architectural Lighting Analysis in Virtual Lighting Laboratory Architectural Lighting Analysis in Virtual Lighting Laboratory Speaker(s): Mehlika Inanici Date: July 7, 2003 - 12:00pm Location: Bldg. 90 Seminar Host/Point of Contact: Satkartar K. Kinney Virtual Lighting Laboratory is a Radiance-based lighting analysis tool and methodology that proposes transformations in the utilization of computer visualization in lighting analysis and design decision-making. It is a computer environment, where the user has been provided with matrices of illuminance and luminance values extracted from high dynamic range images. The principal idea is to provide the laboratory to the designer and researcher to explore various lighting analysis techniques instead of imposing limited number of predetermined metrics. In addition, it introduces an analysis approach for temporal and spatial lighting

417

Home-based Shared Virtual Memory  

E-Print Network (OSTI)

In this dissertation, I investigate how to improve the performance of shared virtual memory (SVM) by examining consistency models, protocols, hardware support and applications. The main conclusion of this research is that the performance of shared virtual memory can be significantly improved when performance-enhancing techniques from all these areas are combined. This dissertation proposes home-based lazy release consistency as a simple, effective, and scalable way to build shared virtual memory systems. In home-based protocols each shared page has a home to which all writes are propagated and from which all copies are derived. Two home-based protocols are described, implemented and evaluated on two hardware and software platforms: Automatic Update Release Consistency (AURC), which requires hardware support for fine-grained remote writes (automatic updates), and Homebased Lazy Release Consistency (HLRC), which is implemented exclusively in software. The dissertation investigates the ...

Liviu Iftode

1998-01-01T23:59:59.000Z

418

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

Science Conference Proceedings (OSTI)

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.

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

419

Virtual radiation fields for ALARA determination  

SciTech Connect

As computing power has increased, so too has the ability to model and simulate complex systems and processes. In addition, virtual reality technology has made it possible to visualize and understand many complex scientific and engineering problems. For this reason, a virtual dosimetry program called Virtual Radiation Fields (VRF) is developed to model radiation dose rate and cumulative dose to a receptor operating in a virtual radiation environment. With the design and testing of many facilities and products taking place in the virtual world, this program facilitates the concurrent consideration of radiological concerns during the design process. Three-dimensional (3D) graphical presentation of the radiation environment is made possible through the use of IGRIP, a graphical modeling program developed by Deneb Robotics, Inc. The VRF simulation program was designed to model and display a virtual dosimeter. As a demonstration of the program`s capability, the Hanford tank, C-106, was modeled to predict radiation doses to robotic equipment used to remove radioactive waste from the tank. To validate VRF dose predictions, comparison was made with reported values for tank C-106, which showed agreement to within 0.5%. Graphical information is presented regarding the 3D dose rate variation inside the tank. Cumulative dose predictions were made for the cleanup operations of tank C-106. A four-dimensional dose rate map generated by VRF was used to model the dose rate not only in 3D space but also as a function of the amount of waste remaining in the tank. This allowed VRF to predict dose rate at any stage in the waste removal process for an accurate simulation of the radiological conditions throughout the tank cleanup procedure.

Knight, T.W.

1995-12-31T23:59:59.000Z

420

Structure of the mean velocity and turbulence in premixed axisymmetric acetylene flames  

Science Conference Proceedings (OSTI)

Laser-Doppler measurements of axial mean velocities and the corresponding rms values of turbulent velocity fluctuations are reported for premixed, axisymmetric, acetylene flames together with the probability density distributions of the turbulent velocity fluctuations. All this information provides an insight into the structure of the flow field. Characteristic zones of the flow field are defined that show common features for all acetylene flames studied by the authors. These features are discussed in the paper and are suggested to characterize, in general, interesting parts of the flames.

Matovic, M.; Oka, S. (Inst. for Thermal Engineering and Energy Research, Beograd (Yugoslavia)); Durst, F. (Univ. Erlangen-Nuernberg, Erlangen (Germany). Lehrstuhl fuer Stroemungsmechanik)

1994-09-01T23:59:59.000Z

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Some aspects of virtual black holes  

SciTech Connect

We first consider consistently third-quantize modified gravity. We then analyze certain aspects of virtual black holes in this third-quantized modified gravity. We see how a statistical mechanical origin for the Bekenstein-Hawking entropy naturally arises in this model. Furthermore, the area and hence the entropy of a real macroscopic black hole is quantized in this model. Virtual black holes cause a loss of quantum coherence, which gives an intrinsic entropy to all physical systems that can be used to define a direction of time and hence provide a solution to the problem of time.

Faizal, M., E-mail: faizal.mir@durham.ac.uk [University of Durham, Department of Mathematics (United Kingdom)

2012-03-15T23:59:59.000Z

422

Ion mobility spectrometer with virtual aperture grid  

DOE Patents (OSTI)

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.

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

2010-11-23T23:59:59.000Z

423

Combustor oscillating pressure stabilization and method  

DOE Patents (OSTI)

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.

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

424

Combustor oscillating pressure stabilization and method  

DOE Patents (OSTI)

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. 7 figs.

Gemmen, R.S.; Richards, G.A.; Yip, M.T.J.; Robey, E.H.; Cully, S.R.; Addis, R.E.

1998-08-11T23:59:59.000Z

425

Composite stabilizer unit  

DOE Patents (OSTI)

This invention is comprised of an improved fin stabilized projectile including multiple stabilizer fins upon a stabilizer unit situated at the aft end of the projectile is provided, the improvement wherein the stabilizer fins are joined into the stabilizer unit by an injection molded engineering grade polymer.

Ebaugh, L.R.; Sadler, C.P.; Carter, G.D.

1990-12-31T23:59:59.000Z

426

Composite stabilizer unit  

DOE Patents (OSTI)

This invention is comprised of an improved fin stabilized projectile including multiple stabilizer fins upon a stabilizer unit situated at the aft end of the projectile is provided, the improvement wherein the stabilizer fins are joined into the stabilizer unit by an injection molded engineering grade polymer.

Ebaugh, L.R.; Sadler, C.P.; Carter, G.D.

1990-01-01T23:59:59.000Z

427

Composite stabilizer unit  

SciTech Connect

An improved fin stabilized projectile including multiple stabilizer fins upon a stabilizer unit situated at the aft end of the projectile is provided, the improvement wherein the stabilizer fins are joined into the stabillizer unit by an injection molded engineering grade polymer.

Ebaugh, Larry R. (Los Alamos, NM); Sadler, Collin P. (Los Alamos, NM); Carter, Gary D. (Espanola, NM)

1992-01-01T23:59:59.000Z

428

FLAME-SAMPLING PHOTOIONIZATION MASS SPECTROSCOPY - FINAL TECHNICAL REPORT  

SciTech Connect

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.

Hansen, Nils

2013-02-12T23:59:59.000Z

429

Multiple mapping conditioning of velocity in turbulent jet flames  

Science Conference Proceedings (OSTI)

Multiple mapping conditioning (MMC) has emerged as a new approach to model turbulent reacting flows. This study revises the standard MMC closure for velocity in turbulent jet flows from linearity in the reference space to linearity in the composition space. This modeling amendment ensures that the standard velocity model in conditional moment closure studies can now be used for MMC computation as well. A simplified model for the velocity-dependence of MMC drift coefficients is derived without loss of generality and is implemented for the revised velocity closure. Modeling results have been corroborated against the Direct Numerical Simulation database of a spatially evolving, planar turbulent jet flame. The revised model shows marked improvement over standard MMC closure in predicting velocity statistics close to the nozzle. (author)

Vaishnavi, P. [Mechanical Engineering Department, Imperial College, London SW7 2AZ (United Kingdom); Kronenburg, A. [Institut fuer Technische Verbrennung, Universitaet Stuttgart, 70174 Stuttgart (Germany)

2010-10-15T23:59:59.000Z

430

Experimental study of flame propagation in semiconfined geometries with obstacles  

DOE Green Energy (OSTI)

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

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

1982-02-08T23:59:59.000Z

431

Navigation, Wayfinding, and Place Experience within a Virtual City  

Science Conference Proceedings (OSTI)

We report a qualitative study of navigation, wayfinding, and place experience within a virtual city. “Cityscape” is a virtual environment (VE), partially algorithmically generated and intended to be redolent of the aggregate forms of real ...

Craig D. Murray; John M. Bowers; Adrian J. West; Steve Pettifer; Simon Gibson

2000-10-01T23:59:59.000Z

432

The Mobile Animator: Interactive Character Animation in Collaborative Virtual Environments  

Science Conference Proceedings (OSTI)

We have designed a mobile -PDA-based- interfacefor real-time control of virtual characters in multiusersemi-immersive Virtual Environments -using a large rear-projectionscreen. The proof-of-concept implementation wepresent shows the potential of handheld ...

Mario Gutiérrez; Frédéric Vexo; Daniel Thalmann

2004-03-01T23:59:59.000Z

433

Development of extensible virtual instruments for SCADA applications  

Science Conference Proceedings (OSTI)

This paper presents an architecture and design of a solution for virtual instrumentation in SCADA systems. The aim of this approach is to propose a way to design virtual instrumentation based on software components, which ensures uniform, consistent ...

Traian Turc; Adrian Gligor; Cristian Dumitru; Alexandru Morar

2010-05-01T23:59:59.000Z

434

Perspective isosurface and direct volume rendering for virtual endoscopy applications  

Science Conference Proceedings (OSTI)

Virtual endoscopy has proven to be a very powerful tool in endoscopic surgery. However, most virtual endoscopy systems are restricted to rendering isosurfaces or require segmentation in order to visualize additional objects behind occluding tissue. This ...

Henning Scharsach; Markus Hadwiger; André Neubauer; Stefan Wolfsberger; Katja Bühler

2006-05-01T23:59:59.000Z

435

DOE Virtual Library of Energy Science and Technology | OSTI,...  

Office of Scientific and Technical Information (OSTI)

DOE Virtual Library of Energy Science and Technology DOE Virtual Library of Energy Science and Technology April 13, 1999 Walter L. Warnick, Ph.D., Director Office of Scientific and...

436

Integrating Pedagogical Agents into Virtual Environments  

Science Conference Proceedings (OSTI)

In order for a virtual environment to be effective as a training tool, it is not enough to concentrate on the fidelity of the renderings and the accuracy of the simulated behaviors. The environment should help trainees develop an understanding of the ...

W. Lewis Johnson; Jeff Rickel; Randy Stiles; Allen Munro

1998-12-01T23:59:59.000Z

437

Environmental-aware virtual data center network  

Science Conference Proceedings (OSTI)

Cloud computing services have recently become a ubiquitous service delivery model, covering a wide range of applications from personal file sharing to being an enterprise data warehouse. Building green data center networks providing cloud computing services ... Keywords: Green ICT, GreenStar Network, Mantychore FP7, Neutral carbon network, Virtual data center

Kim Khoa Nguyen; Mohamed Cheriet; Mathieu Lemay; Victor Reijs; Andrew Mackarel; Alin Pastrama

2012-07-01T23:59:59.000Z

438

A virtual environment for network testing  

Science Conference Proceedings (OSTI)

The testing of network-based solutions demands a series of tedious tasks such as the deployment of the solution at different nodes and the configuration of different topologies. The manual execution of these tasks is very time consuming and a configurable ... Keywords: Re-configuration, Software testing, Virtual network

Wade A. Fagen; João W. Cangussu; Ram Dantu

2009-01-01T23:59:59.000Z

439

Intelligent content production for a virtual speaker  

Science Conference Proceedings (OSTI)

We present a graphically embodied animated agent (a virtual speaker) capable of reading a plain English text and rendering it in a form of speech accompanied by the appropriate facial gestures. Our system uses a lexical analysis of an English text and ...

Karlo Smid; Igor S. Pandzic; Viktorija Radman

2004-09-01T23:59:59.000Z

440

Applications of Virtual Reality to Nuclear Safeguards  

SciTech Connect

This paper explores two potential applications of Virtual Reality (VR) to international nuclear safeguards: training and information organization and navigation. The applications are represented by two existing prototype systems, one for training nuclear weapons dismantlement and one utilizing a VR model to facilitate intuitive access to related sets of information.

Stansfield, S.

1998-11-03T23:59:59.000Z

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Towards a virtual organization for data cyberinfrastructure  

Science Conference Proceedings (OSTI)

We report on the exploratory stages of multi-university, multi-research-site, multi-year effort to investigate and compare data practices in multiple cyberinfrastructure projects and their emerging virtual organizations. Our long-term goal is to understand ... Keywords: collaborative work, cyberinfrastructure, scientific data, sensor networks

Christine L. Borgman; Geoffrey C. Bowker; Thomas A. Finholt; Jillian C. Wallis

2009-06-01T23:59:59.000Z

442

Creating Chinkin works in the virtual space  

Science Conference Proceedings (OSTI)

In this paper, a method to enable people to experience "Chinkin" in the virtual space is introduced. Chinkin is a traditional artistic technique to draw designs on lacquer ware with fine lines and dots, and it was widely used to produce Daimyo's utensils ...

Shinji Mizuno

2011-10-01T23:59:59.000Z

443

Virtual Prairie: Going Green with Volunteer Computing  

Science Conference Proceedings (OSTI)

A Multi-species prairie composed primarily of clonal plants can achieve different ecological functions. They can be a good source of biofuel, a mean of water purification in agriculture or a biodiversity guardian. The goal of the Virtual Prairie project ...

Malek Smaoui; Marc Garbey; Cendrine Mony

2008-12-01T23:59:59.000Z

444

Real-time individualized virtual humans  

Science Conference Proceedings (OSTI)

This tutorial will present the latest techniques to model fast individualized animatable virtual humans for Real-Time applications. As a human is composed of a head and a body, we will analyze how these two parts can be modeled and globally animated ...

Nadia Magnenat-Thalmann; Daniel Thalmann

2008-12-01T23:59:59.000Z

445

Prudhoe Bay Oil Production Optimization: Using Virtual  

E-Print Network (OSTI)

total field oil production by optimizing the gas discharge rates and pressures at the separation1 Prudhoe Bay Oil Production Optimization: Using Virtual Intelligence Techniques, Stage One: Neural Model Building Shahab D. Mohaghegh, West Virginia University Lynda A. Hutchins, BP Exploration (Alaska

Mohaghegh, Shahab

446

Green Flexible Opportunistic Computing with Virtualization  

Science Conference Proceedings (OSTI)

Energy efficiency and High computing power are basic design considerations across modern-day computing solutions due to different concerns such as system performance, operational cost, and environmental issues. Opportunistic grid infrastructures offer ... Keywords: grid computing, opportunistic computing, scalable architectures, energy-aware systems, virtualization, performance of systems

Harold Castro; German Sotelo; Cesar O. Diaz; Pascal Bouvry

2011-08-01T23:59:59.000Z

447

On The Toxicity of Flame Retardants in Buildings and What Can Be Done About  

NLE Websites -- All DOE Office Websites (Extended Search)

On The Toxicity of Flame Retardants in Buildings and What Can Be Done About On The Toxicity of Flame Retardants in Buildings and What Can Be Done About It Speaker(s): Arlene Blum Date: November 3, 2010 - 12:00pm Location: 90-3122 Seminar Host/Point of Contact: William Fisk Polystyrene, polyisocyanurate, and polyurethane are insulation materials that increase energy efficiency and whose use in buildings, especially energy efficient buildings, is growing rapidly. At the same time, the flame retardants currently in use with these materials are often chemicals that are known to be toxic or have not been adequately evaluated for their impact on human health and the environment. For example, all polystyrene foam insulation used in buildings is treated with HBCD, a persistent, bioaccumulative, and toxic flame retardant. The impacts of exposure to

448

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

Science Conference Proceedings (OSTI)

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.

Kong, Peter C

2013-11-26T23:59:59.000Z

449

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

E-Print Network (OSTI)

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

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

2007-01-01T23:59:59.000Z

450

The Soret Effect in Naturally Propagating, Premixed, Lean, Hydrogen-Air Flames  

E-Print Network (OSTI)

3] R. W. Shefer, Int. J. Hydrogen Energ. 28 (2003) 1131–Propagating, Premixed, Lean, Hydrogen-Air Flames Joseph F.diffusion effects in lean hydrogen-air ?ames, in spite of

Grcar, Joseph F

2008-01-01T23:59:59.000Z

451

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

E-Print Network (OSTI)

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

Chin, W.K.

2011-01-01T23:59:59.000Z

452

Multigrid Solution Of Flame Sheet Problems On Serial And Parallel Computers  

E-Print Network (OSTI)

. Flame sheet problems are on the natural route to the numerical solution of detailed chemistry, laminar diffusion flames, which, in turn, are important in many engineering applications. In order to model the flame structure more accurately, we use the vorticity-velocity formulation of the fluid flow equations instead of the more traditional stream function-vorticity approach. The numerical solution of the resulting nonlinear coupled elliptic partial differential equations involves damped Newton iterations, adaptive grid procedures, and multigrid methods. We focus on nonlinear damped Newton multigrid, using either one way or correction schemes. Results on serial and parallel processors are presented. Key words. multigrid, combustion, flame sheet, Navier-Stokes, vorticity-velocity, nonlinear methods, iterative methods, parallel computing. AMS(MOS) subject classifications. 80A32, 80-08, 65C20, 65N20, 65F10. 1. Introduction. The difficulties associated with solving high heat release co...

Craig Douglas; Alexandre Ern; Mitchell; D. Smooke

1994-01-01T23:59:59.000Z

453

Education: Digital Resource Center - WEB: The Virtual Nuclear Tourist  

Science Conference Proceedings (OSTI)

Sep 24, 2007 ... The Virtual Nuclear Tourist website provides extensive balanced information about nuclear power plants. Topics include nuclear power ...

454

An application of shared virtual reality to situational training  

Science Conference Proceedings (OSTI)

This paper presents current research being undertaken at Sandia National Laboratories to develop a distributed, shared virtual reality simulation system. The architecture of the system is presented within the framework of an initial application: situational ... Keywords: Sandia National Laboratories, computer based training, distributed shared virtual reality simulation, escort training, groupware, inspector training, nuclear nonproliferation treaties, research, shared virtual reality, situational training, user interfaces, virtual reality

S. Stansfield; D. Shawver; N. Miner; D. Rogers

1995-03-01T23:59:59.000Z

455

Providing More Interactivity to Virtual Museums: A Proposal for a VR Authoring Tool  

Science Conference Proceedings (OSTI)

This paper describes the museuVirtual project that is developing an authoring tool for the collaborative building of nonimmersive museums in virtual reality. The rationale behind museuVirtual is based on the observation that virtual museums found on ...

Raul S. Wazlawick; Marta C. Rosatelli; Edla M. F. Ramos; Walter A. Cybis; Bernd H. Storb; Vera R. N. Schuhmacher; Antonio C. Mariani; Tereza Kirner; Claudio Kirner; Lea C. Fagundes

2001-12-01T23:59:59.000Z

456

Spark ignited turbulent flame kernel growth. Annual report, January--December, 1992  

DOE Green Energy (OSTI)

Cyclic combustion variations in spark-ignition engines limit the use of dilute charge strategies for achieving low NO{sub x} emissions and improved fuel economy. Results from an experimental study of the effect of incomplete fuel-air mixing (ifam) on spark-ignited flame kernel growth in turbulent propane-air mixtures are presented. The experiments were conducted in a turbulent flow system that allows for independent variation of flow parameters, ignition system parameters, and the degree of fuel-air mixing. Measurements were made at 1 atm and 300 K conditions. Five cases were studied; a premixed and four incompletely mixed cases with 6%, 13%, 24% and 33% RMS (root-mean-square) fluctuations in the fuel/air equivalence ratio. High speed laser shadowgraphy at 4,000 frames-per-second was used to record flame kernel growth following spark ignition, from which the equivalent flame kernel radius as a function of time was determined. The effect of ifam was evaluated in terms of the flame kernel growth rate, cyclic variations in the flame kernel growth, and the rate of misfire. The results show that fluctuations in local mixture strength due to ifam cause the flame kernel surface to become wrinkled and distorted; and that the amount of wrinkling increases as the degree of ifam. Ifam was also found to result in a significant increase in cyclic variations in the flame kernel growth. The average flame kernel growth rates for the premixed and the incompletely mixed cases were found to be within the experimental uncertainty except for the 33%-RMS-fluctuation case where the growth rate is significantly lower. The premixed and 6%-RMS-fluctuation cases had a 0% misfire rate. The misfire rates were 1% and 2% for the 13%-RMS-fluctuation and 24%-RMS-fluctuation cases, respectively; however, it drastically increased to 23% in the 33%-RMS-fluctuation case.

Santavicca, D.A.

1994-06-01T23:59:59.000Z

457

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

DOE Green Energy (OSTI)

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.

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

1996-03-01T23:59:59.000Z

458

Aromatics oxidation and soot formation in flames. Progress report for year beginning 15 August 1988  

SciTech Connect

Work during this contract period has been concerned with the mechanisms through which aromatics are formed and destroyed in flames, and the processes responsible for soot formation. Recent progress has been primarily in two areas: experiments and modeling of the soot nucleation process in low pressure benzene flames and preparation for experiments on the destruction mechanisms of benzene. In addition, we have incorporated ``weak collision`` formalisms into a fall-off computer code.

Howard, J.B.

1989-12-31T23:59:59.000Z

459

The FLAME DOCTOR Burner Monitoring System: Demonstration Tests at Alliant Energy's Edgewater 5  

Science Conference Proceedings (OSTI)

Accurate knowledge of the quality of the flames of individual burners is essential to advanced boiler management, especially in low-NOx burners, which are more sensitive to changes in operation and fuel quality than conventional burners. New technology is needed that permits direct, continuous monitoring of each burner in a boiler. One promising technology that addresses these needs is the FLAME DOCTOR® system developed under EPRI sponsorship. This report summarizes the results from the second full-s...

2004-11-23T23:59:59.000Z

460

Ada and grace: toward realistic and engaging virtual museum guides  

Science Conference Proceedings (OSTI)

To increase the interest and engagement of middle school students in science and technology, the InterFaces project has created virtual museum guides that are in use at the Museum of Science, Boston. The characters use natural language interaction and ... Keywords: STEM, informal science education, natural language interaction, photoreal characters, virtual human applications, virtual museum guides

William Swartout; David Traum; Ron Artstein; Dan Noren; Paul Debevec; Kerry Bronnenkant; Josh Williams; Anton Leuski; Shrikanth Narayanan; Diane Piepol; Chad Lane; Jacquelyn Morie; Priti Aggarwal; Matt Liewer; Jen-Yuan Chiang; Jillian Gerten; Selina Chu; Kyle White

2010-09-01T23:59:59.000Z

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

Energy Efficient Allocation of Virtual Machines in Cloud Data Centers  

Science Conference Proceedings (OSTI)

Rapid growth of the demand for computational power has led to the creation of large-scale data centers. They consume enormous amounts of electrical power resulting in high operational costs and carbon dioxide emissions. Moreover, modern Cloud computing ... Keywords: Energy efficiency, Cloud computing, Energy consumption, Green IT, Resource management, Virtualization, Allocation of virtual machines, Live migration of virtual machines

Anton Beloglazov; Rajkumar Buyya

2010-05-01T23:59:59.000Z

462

Investigation on Virtual Assembly and Motion Simulation of Scroll Compressor  

Science Conference Proceedings (OSTI)

It is efficient and economic to excogitate new product of a scroll compressor by means of virtual design. It accords with development and requirement of scroll compressors products currently. Virtual assembly and motion simulation is important process ... Keywords: scroll compressor, virtual assembly, assembly scheme, motion simulation

Haisheng Li; Yinghua Chen

2010-11-01T23:59:59.000Z

463

Interactive digital storytelling in the sarajevo survival tools virtual environment  

Science Conference Proceedings (OSTI)

Virtual museums enable Internet users to explore museum collections online. The question is how to enhance the viewer's experience and learning in such environments. In the Sarajevo Survival Tools virtual museum we introduced a new concept of interactive ... Keywords: storytelling, user study, virtual museums

Selma Rizvic; Aida Sadzak; Vedad Hulusic; Amela Karahasanovic

2013-03-01T23:59:59.000Z

464

Virtual Wind Speed Sensor for Wind Turbines Andrew Kusiak1  

E-Print Network (OSTI)

Virtual Wind Speed Sensor for Wind Turbines Andrew Kusiak1 ; Haiyang Zheng2 ; and Zijun Zhang3 Abstract: A data-driven approach for development of a virtual wind-speed sensor for wind turbines is presented. The virtual wind-speed sensor is built from historical wind-farm data by data-mining algorithms

Kusiak, Andrew

465

Virtual bidding: the good, the bad and the ugly  

Science Conference Proceedings (OSTI)

Virtual bidding has become an integral part of major organized electricity markets in the U.S. over the last decade; in some markets, virtual bids set the price half the time. Although virtual bidding can enhance the efficiency of electricity markets, that does not come without risk. (author)

Celebi, Metin; Hajos, Attila; Hanser, Philip Q

2010-06-15T23:59:59.000Z

466

Memory-efficient and scalable virtual routers using FPGA  

Science Conference Proceedings (OSTI)

Router virtualization has recently gained much interest in the research community. It allows multiple virtual router instances to run on a common physical router platform. The key metrics in designing network virtual routers are: (1) number of supported ... Keywords: fpga, ip lookup, pipeline, virutal routers

Hoang Le; Thilan Ganegedara; Viktor K. Prasanna

2011-02-01T23:59:59.000Z

467

Transparent Accelerator Migration in a Virtualized GPU Environment  

Science Conference Proceedings (OSTI)

This paper presents a framework to support transparent, live migration of virtual GPU accelerators in a virtualized execution environment. Migration is a critical capability in such environments because it provides support for fault tolerance, on-demand ... Keywords: GPU, Virtualization, OpenCL, Migration, VOCL

Shucai Xiao; Pavan Balaji; James Dinan; Qian Zhu; Rajeev Thakur; Susan Coghlan; Heshan Lin; Gaojin Wen; Jue Hong; Wu-chun Feng

2012-05-01T23:59:59.000Z

468

Virtual environment for solar energy systems design and testing  

Science Conference Proceedings (OSTI)

This paper refers to a virtual environment which represents the main support for experiments with photovoltaic energy systems in the design and testing stage. This software environment is very useful because, compairing to the experiments with real energetic ... Keywords: artificial intelligence, photovoltaic energy systems, simulator, synchronization, virtual environment, virtual experiments

Lucian Milea; Orest Oltu; Marius Stoian; Sanda Osiceanu

2008-07-01T23:59:59.000Z

469

Provisioning Virtual Resources Adaptively in Elastic Compute Cloud Platforms  

Science Conference Proceedings (OSTI)

Provisioning Virtual machines on demand is significant in elastic compute cloud for reliable service delivery. The importance and major difficulty lies in satisfying the conflicting objectives of satisfying contracted service level agreement while lowering ... Keywords: Dynamic Resource Provision, Multi-Tier Applications, Virtual Machines, Virtualized Cloud Platform

Fan Zhang; Junwei Cao; Hong Cai; Cheng Wu

2011-07-01T23:59:59.000Z

470

Network traces of virtual worlds: measurements and applications  

Science Conference Proceedings (OSTI)

Although network traces of virtual worlds are valuable to ISPs (Internet service providers), virtual world software developers, and research communities, they do not exist in the public domain. In this work, we implement a complete testbed to efficiently ... Keywords: traffic measurement, traffic modeling, virtual world

Yichuan Wang; Cheng-Hsin Hsu; Jatinder Pal Singh; Xin Liu

2011-02-01T23:59:59.000Z

471

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

SciTech Connect

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

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

2010-05-15T23:59:59.000Z

472

Capturing the Fire: Flame Energetics and Neutronizaton for Type Ia Supernova Simulations  

E-Print Network (OSTI)

We develop and calibrate a realistic model flame for hydrodynamical simulations of deflagrations in white dwarf (Type Ia) supernovae. Our flame model builds on the advection-diffusion-reaction model of Khokhlov and includes electron screening and Coulomb corrections to the equation of state in a self-consistent way. We calibrate this model flame--its energetics and timescales for energy release and neutronization--with self-heating reaction network calculations that include both these Coulomb effects and up-to-date weak interactions. The burned material evolves post-flame due to both weak interactions and hydrodynamic changes in density and temperature. We develop a scheme to follow the evolution, including neutronization, of the NSE state subsequent to the passage of the flame front. As a result, our model flame is suitable for deflagration simulations over a wide range of initial central densities and can track the temperature and electron fraction of the burned material through the explosion and into the expansion of the ejecta.

A. C. Calder; D. M. Townsley; I. R. Seitenzahl; F. Peng; O. E. B. Messer; N. Vladimirova; E. F. Brown; J. W. Truran; D. Q. Lamb

2006-11-01T23:59:59.000Z

473

Relationships among nitric oxide, temperature and mixture fraction in hydrogen jet flames  

DOE Green Energy (OSTI)

Simultaneous point measurements of NO, the major species, mixture fraction, temperature, and OH are obtained in nonpremixed turbulent hydrogen jet flames, using the combination of spontaneous Raman scattering, Rayleigh scattering, and laser-induced fluorescence. Results are presented for an undiluted hydrogen flame at Reynolds number 10,000 and for flames with 20% and 40% helium dilution. Radial dependence of conditional mean NO mole fraction (conditional on mixture fraction) is shown to be small at upstream locations and negligible at the downstream locations that contribute most to the overall NO emission. Near the flame base, where NO formation rates and concentrations are sensitive to local strain, fluctuations of the NO mole fraction conditional on mixture fraction are 40 to 50% of conditional mean. When average NO levels are calculated conditional on both mixture fraction and temperature, a significant temperature dependence is found. However, this double conditioning does not substantially reduce NO fluctuations relative to the mean values. These results combined with previously reported data on the present hydrogen flames provide a detailed basis for evaluation and refinement of turbulent combustion models for thermal NO{sub x} formation in jet flames.

Barlow, R.S. [Sandia National Labs., Livermore, CA (United States); Carter, C.D. [Systems Research Labs., Inc., Dayton, OH (United States)

1994-01-01T23:59:59.000Z

474

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

E-Print Network (OSTI)

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

Engelmann, Christian

475

Integrating High Performance Computing and Virtual Environments  

E-Print Network (OSTI)

High performance computing has become accepted as a tool that can be used to solve many large scale computational problems. Because of the complexity of the problems associated with high performance computing, visualization of the output of high performance computing applications has always been an important factor in providing a complete problem solving environment for the high performance computing user. As visualization technology advances, it is important to consider what impacts those advances will have on the integration of high performance computing and visualization. Virtual environments are the most recent, and arguably the most powerful, visualization environments in use today. In this paper we analyze the current state of the research of integrating visualization, and in particular virtual environments, with high performance computing. We also present a framework for implementing such an environment and report on the status of its implementation at the Australian National Un...

Brian Corrie; David Sitsky; Paul Mackerras

1997-01-01T23:59:59.000Z

476

Virtual Appliances for Deploying and Maintaining Software  

E-Print Network (OSTI)

This paper attempts to address the complexity of system administration by making the labor of applying software updates independent of the number of computers on which the software is run. Complete networks of machines are packaged up as data; we refer to them as virtual appliances. The publisher of an appliance controls the software installed on the appliance, from the operating system to the applications, and is responsible for keeping the appliance up to date. These appliances can be configured by users to fit their needs; the configuration is captured such that it can be reapplied automatically when the appliance's software is updated. We have developed a compute utility, called the Collective, which assigns virtual appliances to hardware dynamically and automatically. By keeping software up to date, our approach prevents security break-ins due to fixed vulnerabilities.

Constantine Sapuntzakis David; David Brumley; Ramesh Chandra; Nickolai Zeldovich; Jim Chow; Monica S. Lam; Mendel Rosenblum

2003-01-01T23:59:59.000Z

477

Virtual radiation fields for ALARA determination  

Science Conference Proceedings (OSTI)

VRF (virtual radiation fields) was developed to accurately predict the radiation dose received by a person or robotic device with minimum effort. Dose calculations are performed using Monte Carlo techniques while the user interacts with the computer via a user-friendly graphical interface. The code has been utilized for the prediction of radiation doses from the Hanford Reservation waste tanks, particularly tank c-106. This paper describes the features of the code and evaluates it`s application to tank c-106.

Knight, T.W.; Dalton, G.R.; Tulenko, J.S. [Univ. of Flordia, Gainesville, FL (United States)

1995-12-31T23:59:59.000Z

478

Improving query performance in virtual data warehouses  

Science Conference Proceedings (OSTI)

In order to improve the quality of Business Intelligence Systems in an organization we can choose to build the system using BI techniques such as OLAP and data warehousing or by using traditional reports based on SQL queries. The cost and developing ... Keywords: SQL query plans, analytical functions, business intelligence projects, data extraction, indexes, partitioning techniques, query optimization and performance, tuning and optimization, virtual data warehouse

Adela Bâra; Ion Lungu; Manole Velicanu; Vlad Diaconita; Iuliana Botha

2008-05-01T23:59:59.000Z

479

Syngas formation in methane flames and carbon monoxide release during quenching  

SciTech Connect

Following a recent investigation into chemi-ionization and chemiluminescence during gradual aeration of small, laminar methane flames, we proposed that partial oxidation products, or syngas constituents, formed in the pre-flame zone well below the luminous region, were responsible for the observed effects. We therefore map temperature, CO, and H{sub 2} for geometries and conditions relevant to burners in domestic boiler systems, to assess the potential hazard of CO release into the ambient atmosphere, should any partial quenching occur. CO concentrations peaks of 5.5 volume % are recorded in the core surrounding the axis. Appreciable CO concentrations are also found in the absence of added air. Experiments on various burner port geometries and temperatures suggest that this is not due to air entrainment at the flame base but to diffusion from zones closer to the flame. Next, quenching surfaces such as grids, perforated plates and flame trap matrices of different metals are progressively lowered into the flame. To avoid flow line distortion, suction aspirates the quenched products. The highest emission rate occurs with the quenching plane some 4 mm above the burner; further lowering of the quenching surface causes flame extinction. The maximum CO release is close to converting 10% of the CH{sub 4} feed, with some variation with quenching material. Expressing this potential release in terms of, e.g. boiler power, predicts a potentially serious hazard. Results of numerical simulations adequately parallel the experimental sampling profiles and provide insights into local concentrations, as well as the spatially resolved CO flux, which is calculated for a parabolic inlet flow profile. Integration across the stream implies, on the basis of the simulation, a possible tripling of the experimental CO release, were quenching simply to release the local gas composition into the atmosphere. Comparison with experiment suggests some chemical interaction with the quenching surface. (author)

Weinberg, Felix; Carleton, Fred; Houdmont, Raphael [Department of Chemical Engineering, Imperial College, London (United Kingdom); Dunn-Rankin, Derek; Karnani, Sunny [Department of Mechanical and Aerospace Engineering, University of California, Irvine (United States)

2011-02-15T23:59:59.000Z

480

Effect of NO on extinction and re-ignition of vortex-perturbed hydrogen flames.  

DOE Green Energy (OSTI)

The catalytic effect of nitric oxide (NO) on the dynamics of extinction and re-ignition of a vortex-perturbed non-premixed hydrogen-air flame is studied in a counterflow burner. A diffusion flame is established with counterflowing streams of nitrogen-diluted hydrogen at ambient temperature and air heated to a range of temperatures that brackets the auto-ignition temperature. Localized extinction is induced by impulsively driving a fuel-side toroidal vortex into the steady flame, and the recovery of the extinguished region is monitored by planar laser-induced fluorescence (PLIF) of the hydroxyl radical (OH). The dynamics of flame recovery depend on the air temperature and fuel concentration, and four different recovery modes are identified. These modes involve combinations of edge-flame propagation and the expansion of an auto-ignition kernel that forms within the extinguished region. The addition of a small amount of NO significantly alters the re-ignition process by shifting the balance between chain-termination and chain-propagation reactions to enhance auto-ignition. The ignition enhancement by this catalytic effect causes a shift in the conditions that govern the recovery modes. In addition, the effects of NO concentration and vortex strength on the flame recovery are examined. Direct numerical simulations of the flame-vortex interaction with and without NO doping show how the small amount of OH produced by NO-catalyzed reactions has a significant impact on the development of an auto-ignition kernel. This joint experimental and numerical study provides detailed insight into the interaction between transient flows and ignition processes.

Yoo, Chun Sang; Chen, Jacqueline H.; Frank, Jonathan H.; Lee, Uen Do (KITECH, Cheonan, Chungnam, South Korea)

2009-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "flame stabilization virtually" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


481

Experimental and theoretical study of flame inhibition by bromine-containing compounds  

DOE Green Energy (OSTI)

The present paper represents the first effort to date in which a combined experimental and theoretical approach has been used to study the effects of several inhibitors on hydrocarbon-air flames. This work is part of an attempt to build a consistent picture of chemical kinetic flame inhibition, beginning with a simple halogen molecule such as HBr and progressing sequentially towards more complex and more practical inhibitors such as CF/sub 3/Br. Inhibition efficiency can be defined as the rate of flame speed reduction, the amount of flame speed change per unit inhibitor added. Both the numerical model and the flame tube measurements found that the inhibition efficiency gradually decreases as the amount of inhibitor is increased. The present experimental and modeling results are shown, together with earlier data for CF/sub 3/Br-CH/sub 4/-air and CF/sub 3/Br-C/sub 3/H/sub 8/-air as well as HBr-CH/sub 4/-air, CH/sub 3/Br-CH/sub 4/-air and CF/sub 3/Br-CH/sub 4/-air. In the numerical study it was found that a stoichiometric methane-air mixture with up to 8% methyl bromide could support a flame, propagating at a speed of about 5 cm/sec, even though the addition of the first 1% of CH/sub 3/Br had reduced the flame speed from 38 cm/sec to about 26 cm/sec. Extensions of the model to include CF/sub 3/Br are currently under development. The available experimental data suggest that CF/sub 3/Br is somewhat more efficient as an inhibitor than HBr or CH/sub 3/Br.

Westbrook, C.K.; Beason, D.G.; Alvares, N.J.

1981-01-20T23:59:59.000Z

482

Virtual Hydropower Prospector | Open Energy Information  

Open Energy Info (EERE)

Virtual Hydropower Prospector Virtual Hydropower Prospector Jump to: navigation, search Tool Summary LAUNCH TOOL Name: Virtual Hydropower Prospector Agency/Company /Organization: Idaho National Laboratory Sector: Energy Topics: Resource assessment Resource Type: Software/modeling tools User Interface: Website Website: hydropower.inl.gov/prospector/index.shtml Country: United States Cost: Free Northern America Coordinates: 37.09024°, -95.712891° Loading map... {"minzoom":false,"mappingservice":"googlemaps3","type":"ROADMAP","zoom":14,"types":["ROADMAP","SATELLITE","HYBRID","TERRAIN"],"geoservice":"google","maxzoom":false,"width":"600px","height":"350px","centre":false,"title":"","label":"","icon":"","visitedicon":"","lines":[],"polygons":[],"circles":[],"rectangles":[],"copycoords":false,"static":false,"wmsoverlay":"","layers":[],"controls":["pan","zoom","type","scale","streetview"],"zoomstyle":"DEFAULT","typestyle":"DEFAULT","autoinfowindows":false,"kml":[],"gkml":[],"fusiontables":[],"resizable":false,"tilt":0,"kmlrezoom":false,"poi":true,"imageoverlays":[],"markercluster":false,"searchmarkers":"","locations":[{"text":"","title":"","link":null,"lat":37.09024,"lon":-95.712891,"alt":0,"address":"","icon":"","group":"","inlineLabel":"","visitedicon":""}]}

483

A web-based virtual lighting simulator  

SciTech Connect

This paper is about a web-based ''virtual lighting simulator,'' which is intended to allow architects and lighting designers to quickly assess the effect of key parameters on the daylighting and lighting performance in various space types. The virtual lighting simulator consists of a web-based interface that allows navigation through a large database of images and data, which were generated through parametric lighting simulations. At its current form, the virtual lighting simulator has two main modules, one for daylighting and one for electric lighting. The daylighting module includes images and data for a small office space, varying most key daylighting parameters, such as window size and orientation, glazing type, surface reflectance, sky conditions, time of the year, etc. The electric lighting module includes images and data for five space types (classroom, small office, large open office, warehouse and small retail), varying key lighting parameters, such as the electric lighting system, surface reflectance, dimming/switching, etc. The computed images include perspectives and plans and are displayed in various formats to support qualitative as well as quantitative assessment. The quantitative information is in the form of iso-contour lines superimposed on the images, as well as false color images and statistical information on work plane illuminance. The qualitative information includes images that are adjusted to account for the sensitivity and adaptation of the human eye. The paper also includes a section on the major technical issues and their resolution.

Papamichael, Konstantinos; Lai, Judy; Fuller, Daniel; Tariq, Tara

2002-05-06T23:59:59.000Z

484

A web-based virtual lighting simulator  

SciTech Connect

This paper is about a web-based ''virtual lighting simulator,'' which is intended to allow architects and lighting designers to quickly assess the effect of key parameters on the daylighting and lighting performance in various space types. The virtual lighting simulator consists of a web-based interface that allows navigation through a large database of images and data, which were generated through parametric lighting simulations. At its current form, the virtual lighting simulator has two main modules, one for daylighting and one for electric lighting. The daylighting module includes images and data for a small office space, varying most key daylighting parameters, such as window size and orientation, glazing type, surface reflectance, sky conditions, time of the year, etc. The electric lighting module includes images and data for five space types (classroom, small office, large open office, warehouse and small retail), varying key lighting parameters, such as the electric lighting system, surface reflectance, dimming/switching, etc. The computed images include perspectives and plans and are displayed in various formats to support qualitative as well as quantitative assessment. The quantitative information is in the form of iso-contour lines superimposed on the images, as well as false color images and statistical information on work plane illuminance. The qualitative information includes images that are adjusted to account for the sensitivity and adaptation of the human eye. The paper also includes a section on the major technical issues and their resolution.

Papamichael, Konstantinos; Lai, Judy; Fuller, Daniel; Tariq, Tara

2002-05-06T23:59:59.000Z

485

Recent Developments in Virtual Reality Based Education  

E-Print Network (OSTI)

A series of virtual reality based educational modules are being developed to explore the capabilities of this emerging technology, and to determine how and where virtual reality can provide the greatest benefits to engineering educators. The most advanced application, Vicher, has been significantly expanded and split into two modules. Student evaluations of a newly developed safety analysis module show great promise, but also the need for further development. Other modules being developed cover topics in atomic crystal structures, fluid flow characteristics, thermodynamic relationships, and four component azeotropic distillation. This paper will describe the latest developments in the ongoing investigation of virtual reality as an educational medium. INTRODUCTION AND BACKGROUND Engineering educators are making use of an increasing number of computer simulation packages to aid them in attaining their educational objectives 5,7,9,10. The reasons for doing so include the desire to reach students that have alternate learning styles 4,11, to provide experience based education 6, and to augment traditional laboratory facilities that are being stretched increasingly thin with growing enrollments 3.

John T. Bell; H. Scott Fogler

1996-01-01T23:59:59.000Z

486

Precise reddening and metallicity of NGC6752 from FLAMES spectra  

E-Print Network (OSTI)

(abridged) Accurate reddenings for Globular Clusters could be obtained by comparing the colour-temperature obtained using temperatures from reddening-free indicator (Halpha), with that given by standard colour-temperature calibrations. From a single 1300 seconds exposure with FLAMES at VLT2 we obtained spectra centred on Halpha (R=6000, 5

Gratton, R G; Carretta, E; De Angeli, F; Lucatello, S; Momany, Y; Piotto, G; Recio-Blanco, A

2005-01-01T23:59:59.000Z

487

THE EFFECTS OF FLAME TEMPERATURE, PARTICLE SIZE AND EUROPIUM DOPING CONCENTRATION ON THE PROPERTIES OF Y2O3:EU PARTICLES FORMED IN A FLAME AEROSOL PROCESS  

E-Print Network (OSTI)

Y2O3:Eu particles are phosphors that have found wide applications. Flamesynthesized Y2O3:Eu particles may have either the cubic or the monoclinic structure. The effects of particle size and Eu doping concentration on crystal structure and the surface elemental composition of the flame-synthesized Y2O3:Eu particles had not been previously reported. In this study, a flame aerosol process was used to generate polydisperse Y2O3:Eu particle. H2 was used as the fuel gas, with either air or O2 gas as the oxidizer. The precursor was aqueous solutions of the metal nitrates, atomized using a 1.7-MHz ultrasonic atomizer. The product particles were analyzed by transmission electron microscopy (TEM), X-ray diffractometer (XRD), Selected area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS), fluorescence spectrophotometer, and inductively coupled plasma mass spectrometer (ICP-MS). The Y2O3:Eu particles generated in H2/O2 flames were spherical and fully dense, with diameters in the range of 10~3000 nm. In particle