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1

head  

Science Conference Proceedings (OSTI)

DIRECT COMPUTATION OF CONFORMATIONAL FREE ENERGY. Martha S. Head, James A. Given, Michael K. Gilson. ...

2

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

3

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

4

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

5

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

6

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

7

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

8

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

9

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

10

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

11

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

12

Gas Chromatographic Retention Data  

Science Conference Proceedings (OSTI)

... Lee retention indices are determined by analogy with Kovats indices for the following reference compounds: benzene, naphthalene, phenanthrene ...

2013-07-15T23:59:59.000Z

13

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

14

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

15

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

16

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

17

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

18

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

19

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

20

Technetium Retention During LAW Vitrification  

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

retention * More reducing bubbler gases were not effective * For a given glass production rate increase, increased bubbling results in better retention than increased temperature *...

Note: This page contains sample records for the topic "flame retention head" 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

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

22

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

23

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

24

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

25

Hydrogen Retention in Tetraphenylborate Slurries  

DOE Green Energy (OSTI)

Researchers measured the production and retention of gases in potassium tetraphenylborate (KTPB) slurries due to radiolysis.

Peterson, R.A.

1998-10-21T23:59:59.000Z

26

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

27

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

28

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

29

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

30

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

31

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

32

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

33

Polyolefin-based flame retardant material  

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

34

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

35

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

36

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

37

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

38

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

39

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

40

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

Note: This page contains sample records for the topic "flame retention head" 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

Workforce Retention | Department of Energy  

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

Services » Outreach & Collaboration » Focus Groups » Workforce Services » Outreach & Collaboration » Focus Groups » Workforce Retention Workforce Retention The HSS Workforce Retention Work Group was established to collaboratively address the needs of the Department to maintain a skilled work force in the face of anticipated retirements and to address the specific health and safety concerns of that work force that could impede retention. Objectives: Better understand relationship between skilled workforce retention; health, safety and productivity; and especially preventive health care. Inform and support improvement and/or development of wellness, fitness, and prevention programs through data collections and analyses. Promote the implementation of preventive health services designed to assure retention of the contractor work force.

42

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

43

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

44

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

45

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

46

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

47

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

48

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

49

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

50

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

51

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

52

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

53

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

54

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 ) ...

55

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

56

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

57

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.

58

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

59

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

60

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

Note: This page contains sample records for the topic "flame retention head" 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

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

62

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

63

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

64

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

65

Technetium Retention During LAW Vitrification  

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

Technetium Retention During Technetium Retention During LAW Vitrification Ian L. Pegg Vitreous State Laboratory The Catholic University of America Washington, DC November 18, 2010 Overview * Tc in borosilcate glass structure * Re as a surrogate for Tc * Summary of previous data on Tc incorporation into LAW glass * Summary of results from ongoing test program * Single-pass retention vs. retention with recycle * Tc volatilization during container filling Tc in LAW Glass Structure * Tc is present as Tc 7+ and Tc 4+ * Tc 7+ is dominant in more oxidized glasses and Tc 4+ is dominant in reduced glasses * Strongly reducing conditions produce Tc 0 * The structure and local environment of Tc in WTP LAW glasses has been investigated by: * Synchrotron X-Ray Absorption Spectroscopy * Lukens, McKeown, Buechele, Muller, Shuh, and Pegg, Chem. Mater., 19, 559 (2007)

66

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

67

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

68

Records retention in relational database systems  

Science Conference Proceedings (OSTI)

The recent introduction of several pieces of legislation mandating minimum and maximum retention periods for corporate records has prompted the Enterprise Content Management (ECM) community to develop various records retention solutions. Records retention ... Keywords: business records, legal compliance, privacy, records retention, relational systems

Ahmed A. Ataullah; Ashraf Aboulnaga; Frank Wm. Tompa

2008-10-01T23:59:59.000Z

69

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.

70

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.

71

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.

72

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...

73

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

74

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...

75

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 ...

76

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

77

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

78

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

79

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

80

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

Note: This page contains sample records for the topic "flame retention head" 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

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

82

Retention of hydrogen in graphite  

DOE Green Energy (OSTI)

The retention of hydrogen in POCO AXF-5Q graphite has been measured at room temperature as a function of fluence and flux for H/sub 2//sup +/ ions at energies from 250 to 500 eV provided by a glow discharge. More than 2 x 10/sup 18/ H/cm/sup 2/ has been retained, and no indication of saturation has been observed to a fluence of 5 x 10/sup 19/ H/cm/sup 2/. In this experiment, retention was found to increase linearly with fluence for constant flux. A flux dependence was observed; that is, the retention rate was observed to decrease monotonically as the flux increased. A change-over experiment, deuterium to hydrogen, was conducted; the results show that significant change-over occurs (i.e., about 30% change-over for a fluence of 5 x 10/sup 17/ D/cm/sup 2/).

Langley, R.A.

1986-10-01T23:59:59.000Z

83

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

84

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

85

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

86

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

87

Mechanisms of gas bubble retention  

Science Conference Proceedings (OSTI)

Retention and episodic release of flammable gases are critical safety concerns regarding double-shell tanks (DSTs) containing waste slurries. Previous investigations have concluded that gas bubbles are retained by the slurry that has settled at the bottom of the DST. However, the mechanisms responsible for the retention of these bubbles are not well understood. In addition, the presence of retained gas bubbles is expected to affect the physical properties of the sludge, but essentially no literature data are available to assess the effect of these bubbles. The rheological behavior of the waste, particularly of the settled sludge, is critical to characterizing the tendency of the waste to retain gas bubbles. The objectives of this study are to elucidate the mechanisms contributing to gas bubble retention and release from sludge such as is in Tank 241-SY-101, understand how the bubbles affect the physical properties of the sludge, develop correlations of these physical properties to include in computer models, and collect experimental data on the physical properties of simulated sludges with bubbles. This report presents a theory and experimental observations of bubble retention in simulated sludge and gives correlations and new data on the effect of gas bubbles on sludge yield strength.

Gauglitz, P.A.; Mahoney, L.A.; Mendoza, D.P.; Miller, M.C.

1994-09-01T23:59:59.000Z

88

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

89

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

90

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

91

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.

92

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

93

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

94

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

95

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

96

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

97

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

98

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

99

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.

100

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

Note: This page contains sample records for the topic "flame retention head" 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

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

102

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

103

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

104

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.

105

Maneuvering impact boring head  

DOE Patents (OSTI)

An impact boring head may comprise a main body having an internal cavity with a front end and a rear end. A striker having a head end and a tail end is slidably mounted in the internal cavity of the main body so that the striker can be reciprocated between a forward position and an aft position in response to hydraulic pressure. A compressible gas contained in the internal cavity between the head end of the striker and the front end of the internal cavity returns the striker to the aft position upon removal of the hydraulic pressure.

Zollinger, W. Thor (Idaho Falls, ID); Reutzel, Edward W. (Idaho Falls, ID)

1998-01-01T23:59:59.000Z

106

Maneuvering impact boring head  

DOE Patents (OSTI)

An impact boring head may comprise a main body having an internal cavity with a front end and a rear end. A striker having a head end and a tail end is slidably mounted in the internal cavity of the main body so that the striker can be reciprocated between a forward position and an aft position in response to hydraulic pressure. A compressible gas contained in the internal cavity between the head end of the striker and the front end of the internal cavity returns the striker to the aft position upon removal of the hydraulic pressure. 8 figs.

Zollinger, W.T.; Reutzel, E.W.

1998-08-18T23:59:59.000Z

107

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

108

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

109

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

110

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

111

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

112

Radionuclide Retention in Concrete Wasteforms  

SciTech Connect

Assessing long-term performance of Category 3 waste cement grouts for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e., sorption or precipitation); the mechanism of contaminant release; the significance of contaminant release pathways; how wasteform performance is affected by the full range of environmental conditions within the disposal facility; the process of wasteform aging under conditions that are representative of processes occurring in response to changing environmental conditions within the disposal facility; the effect of wasteform aging on chemical, physical, and radiological properties; and the associated impact on contaminant release. This knowledge will enable accurate prediction of radionuclide fate when the wasteforms come in contact with groundwater. Data collected throughout the course of this work will be used to quantify the efficacy of concrete wasteforms, similar to those used in the disposal of LLW and MLLW, for the immobilization of key radionuclides (i.e., uranium, technetium, and iodine). Data collected will also be used to quantify the physical and chemical properties of the concrete affecting radionuclide retention.

Wellman, Dawn M.; Jansik, Danielle P.; Golovich, Elizabeth C.; Cordova, Elsa A.

2012-09-24T23:59:59.000Z

113

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

114

DOE Handbook on Recruitment and Retention Incentives  

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

This publication provides sample plans, service agreements, and management worksheets for administering recruitment, relocation, and retention incentives and repayment of student loans.

115

Stationary Phases in Gas Chromatographic Retention Data  

Science Conference Proceedings (OSTI)

... lists below contain names of stationary phases found in the gas chromatography retention ... CP Sil 2; Nonpolar; LM-5; JXR; Vacuum Grease Oil (VM-4) ...

2013-07-15T23:59:59.000Z

116

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

117

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

118

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

119

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

120

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

Note: This page contains sample records for the topic "flame retention head" 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

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

122

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

123

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

124

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

125

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

126

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

127

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

128

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

129

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

130

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...

131

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 ...

132

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

133

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...

134

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

135

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

136

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 ...

137

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...

138

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

139

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

140

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

Note: This page contains sample records for the topic "flame retention head" 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

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 ...

142

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

143

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.

144

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

145

Radionuclide Retention in Concrete Wasteforms  

Science Conference Proceedings (OSTI)

Assessing long-term performance of Category 3 waste cement grouts for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e., sorption or precipitation); the mechanism of contaminant release; the significance of contaminant release pathways; how wasteform performance is affected by the full range of environmental conditions within the disposal facility; the process of wasteform aging under conditions that are representative of processes occurring in response to changing environmental conditions within the disposal facility; the effect of wasteform aging on chemical, physical, and radiological properties; and the associated impact on contaminant release. This knowledge will enable accurate prediction of radionuclide fate when the wasteforms come in contact with groundwater. The information present in the report provides data that (1) measures the effect of concrete wasteform properties likely to influence radionuclide migration; and (2) quantifies the rate of carbonation of concrete materials in a simulated vadose zone repository.

Bovaird, Chase C.; Jansik, Danielle P.; Wellman, Dawn M.; Wood, Marcus I.

2011-09-30T23:59:59.000Z

146

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

147

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

148

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

149

Reactor pressure vessel vented head  

DOE Patents (OSTI)

A head for closing a nuclear reactor pressure vessel shell includes an arcuate dome having an integral head flange which includes a mating surface for sealingly mating with the shell upon assembly therewith. The head flange includes an internal passage extending therethrough with a first port being disposed on the head mating surface. A vent line includes a proximal end disposed in flow communication with the head internal passage, and a distal end disposed in flow communication with the inside of the dome for channeling a fluid therethrough. The vent line is fixedly joined to the dome and is carried therewith when the head is assembled to and disassembled from the shell.

Sawabe, James K. (San Jose, CA)

1994-01-11T23:59:59.000Z

150

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

151

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

152

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

153

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

154

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.

155

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

156

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

157

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

158

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

159

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

160

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

Note: This page contains sample records for the topic "flame retention head" 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

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

162

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

163

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

164

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

165

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

166

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

167

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

168

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

169

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

170

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

171

Reactor pressure vessel vented head  

DOE Patents (OSTI)

A head for closing a nuclear reactor pressure vessel shell includes an arcuate dome having an integral head flange which includes a mating surface for sealingly mating with the shell upon assembly therewith. The head flange includes an internal passage extending therethrough with a first port being disposed on the head mating surface. A vent line includes a proximal end disposed in flow communication with the head internal passage, and a distal end disposed in flow communication with the inside of the dome for channeling a fluid therethrough. The vent line is fixedly joined to the dome and is carried therewith when the head is assembled to and disassembled from the shell. 6 figures.

Sawabe, J.K.

1994-01-11T23:59:59.000Z

172

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...

173

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

174

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

175

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...

176

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

177

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

178

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

179

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

180

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

Note: This page contains sample records for the topic "flame retention head" 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

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

182

DOE Handbook on Recruitment and Retention Incentives | Department of Energy  

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

Handbook on Recruitment and Retention Incentives Handbook on Recruitment and Retention Incentives DOE Handbook on Recruitment and Retention Incentives This desk reference contains sample recruitment, relocation, retention, and student loan incentive plans and service agreements for eligible employees; sample worksheets to assist in documenting the justification and approvals for all types of recruitment and retention incentives; information on superior qualification determinations; guidance and sample documents regarding crediting directly-related service for annual leave for new appointments; frequently asked questions regarding relocation expenses; and other relevant documents. This desk reference is intended to supplement information currently available in the following references. DOE Handbook on Recruitment and Retention Incentives

183

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

184

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

185

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

186

Work Force Retention Work Group Charter  

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

The Work force Retention Work Group is established to support the Department’s critical focus on maintaining a high-performing work force at a time when a significant number of the workers needed to support DOE’s national security mission are reaching retirement age.

187

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

188

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

189

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

190

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

191

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

192

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

193

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

194

STUDY OF HELIUM RETENTION IN NANO-CAVITY ...  

Science Conference Proceedings (OSTI)

STUDY OF HELIUM RETENTION IN NANO-CAVITY TUNGSTEN AS A FIRST WALL IN A FUSION CHAMBER USING NEUTRON DEPTH ...

195

The purpose of this Record Retention and Destruction Policy  

Science Conference Proceedings (OSTI)

management systems; and. • recorded audio ... Schedule (Attachment A) that is approved as the maintenance, retention and disposal schedule for official ...

196

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

197

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

198

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

199

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

200

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

Note: This page contains sample records for the topic "flame retention head" 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

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

202

Heater head for stirling engine  

DOE Patents (OSTI)

A monolithic heater head assembly which augments cast fins with ceramic inserts which narrow the flow of combustion gas and obtains high thermal effectiveness with the assembly including an improved flange design which gives greater durability and reduced conduction loss.

Corey, John A. (R.D. #2, Box 101 E, North Troy, NY 12182)

1985-07-09T23:59:59.000Z

203

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

204

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

205

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

206

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

207

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

208

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

209

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

210

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

211

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

212

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

213

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

214

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

215

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

216

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

217

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

218

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

219

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

220

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

Note: This page contains sample records for the topic "flame retention head" from the National Library of EnergyBeta (NLEBeta).
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221

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

222

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.

223

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

224

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

225

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

226

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

227

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

228

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

229

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

230

Heater head for Stirling engine  

SciTech Connect

This patent describes a heater head for a Stirling engine comprising: a housing for enclosing the heater head with gas at a substantial elevated pressure; insulator means attached to the housing for insulating the heater head; inlet means attached to a regenerator in the housing for admission of relatively high pressure working fluid from the regenerator of a Stirling engine; a first annular heating wall in the housing attached to the inlet means for heating the working fluid; and, a second annular heating wall in the housing concentric with the first heating wall but of lesser diameters so that an annular space is formed between the first heating wall and the second heating wall for heating working fluid; and a third heating wall in the housing concentric with and smaller in diameter than the second heating wall forming the condensing area of a heat pipe between the second heating wall and the third heating wall.

White, M.A.; Emigh, S.G.

1987-06-09T23:59:59.000Z

231

Roundness of Molded Detonator Heads  

SciTech Connect

The magnitude of the deviations from roundness of molded detonator heads, caused by the geometry of the part and by different materials, was investigated to provide a scientific basis which can be used to predict dimensions and tolerances of size and roundness for new heads. Injection presses were used to mold detonator heads to precision tolerances. Twenty parts were molded under optimum conditions in two different molds using both DAP filled with long glass fibers and DAP filled with asbestos. Each of the parts was analyzed for size and roundness, and the data were analyzed statistically. The results indicate: 1. Geometry is highly significant. 2. Material is highly significant. 3. Geometry and material do not interact. 4. Geometry affects magnitude of deviation from roundness. 5. Geometry affects magnitude of shrinkage.

Wendeln, D. E.; Waldfogle, E. A.

1968-12-12T23:59:59.000Z

232

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

233

Rotating control head applications increasing  

Science Conference Proceedings (OSTI)

Rotating control head technology has become an important tool for lowering drilling costs and increasing well productivity, especially in many hard-rock areas and mature oil and gas fields. Lower drilling costs are achieved primarily by the faster penetration rates, reduced nondrilling time, and reduced mud volume requirements associated with underbalanced drilling. Greater well productivity can sometimes be obtained because of reduced formation damage for mud. Recent advances in rotating head technology have increased the range of well conditions to which this technology can be applied. Even though the use of rotating control heads is growing rapidly, this topic has been largely neglected in most well control training programs. Many engineers are not yet familiar with this important emerging technology and some of the modern concepts and practices used. The paper discusses the high-pressure rotating head and its application to gas or air drilling, flow drilling, geothermal drilling, overbalanced drilling and workover operations. The paper also discusses operating guidelines and rig crew training.

Bourgoyne, A.T. Jr. [Louisiana State Univ., Baton Rouge, LA (United States)

1995-10-09T23:59:59.000Z

234

Moisture retention properties of a mycorrhizal soil  

E-Print Network (OSTI)

The water relations of arbuscular mycorrhizal plants have been compared often, but virtually nothing is known about the comparative water relations of mycorrhizal and nonmycorrhizal soils. Mycorrhizal symbiosis typically affects soil structure, and soil structure affects water retention properties; therefore, it seems likely that mycorrhizal symbiosis may affect soil water relations. We examined the water retention properties of a Sequatchie fine sandy loam subjected to three treatments: seven months of root growth by (1) nonmycorrhizal Vigna unguiculata given low phosphorus fertilization, (2) nonmycorrhizal Vigna unguiculata given high phosphorus fertilization, (3) Vigna unguiculata colonized by Glomus intraradices and given low phosphorus fertilization. Mycorrhization of soil had a slight but significant effect on the soil moisture characteristic curve. Once soil matric potential (\\11m) began to decline, changes in \\II m per unit change in soil water content were smaller in mycorrhizal than in the two nonmycorrhizal soils. Within the range of about-1 to-5 MPa, the mycorrhizal soil had to dry more than the nonmycorrhizal soils to reach the same \\11m. Soil characteristic curves of non mycorrhizal soils were similar, whether they contained roots of plants fed high or low phosphorus. The mycorrhizal soil had significantly more water stable aggregates and substantially higher extraradical hyphal densities than the nonmycorrhizal soils. Importantly, we were able to factor out the possibly confounding influence of differential root growth among mycorrhizal and nonmycorrhizal

Robert M. Augel; Ann L. W. Stodola; Layme E. Tims; Arnold M. Saxton

2000-01-01T23:59:59.000Z

235

Radionuclide Retention in Concrete Wasteforms - FY13  

SciTech Connect

Assessing long-term performance of Category 3 waste cement grouts for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e., sorption or precipitation); the mechanism of contaminant release; the significance of contaminant release pathways; how wasteform performance is affected by the full range of environmental conditions within the disposal facility; the process of wasteform aging under conditions that are representative of processes occurring in response to changing environmental conditions within the disposal facility; the effect of wasteform aging on chemical, physical, and radiological properties; and the associated impact on contaminant release. This knowledge will enable accurate prediction of radionuclide fate when the wasteforms come in contact with groundwater. Data collected throughout the course of this work will be used to quantify the efficacy of concrete wasteforms, similar to those used in the disposal of low-level waste and mixed low-level waste, for the immobilization of key radionuclides (i.e., uranium, technetium, and iodine). Data collected will also be used to quantify the physical and chemical properties of the concrete affecting radionuclide retention.

Snyder, Michelle MV; Golovich, Elizabeth C.; Wellman, Dawn M.; Crum, Jarrod V.; Lapierre, Robert; Dage, Denomy C.; Parker, Kent E.; Cordova, Elsa A.

2013-10-15T23:59:59.000Z

236

Radionuclide Retention in Concrete Waste Forms  

Science Conference Proceedings (OSTI)

Assessing long-term performance of Category 3 waste cement grouts for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e., sorption or precipitation); the mechanism of contaminant release; the significance of contaminant release pathways; how waste form performance is affected by the full range of environmental conditions within the disposal facility; the process of waste form aging under conditions that are representative of processes occurring in response to changing environmental conditions within the disposal facility; the effect of waste form aging on chemical, physical, and radiological properties; and the associated impact on contaminant release. This knowledge will enable accurate prediction of radionuclide fate when the waste forms come in contact with groundwater. The information presented in the report provides data that 1) quantify radionuclide retention within concrete waste form materials similar to those used to encapsulate waste in the Low-Level Waste Burial Grounds (LLBG); 2) measure the effect of concrete waste form properties likely to influence radionuclide migration; and 3) quantify the stability of uranium-bearing solid phases of limited solubility in concrete.

Mattigod, Shas V.; Bovaird, Chase C.; Wellman, Dawn M.; Wood, Marcus I.

2010-09-30T23:59:59.000Z

237

Factors Associated with Increasing Teacher Retention in Rural Schools.  

E-Print Network (OSTI)

??This paper seeks to identify school-based factors associated with increasing teacher retention in rural public schools. Though there is a large body of research that… (more)

Rutenberg, David

238

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

239

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

240

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 retention head" 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

Intergranular Cracking of Brass Sprinkler Heads  

Science Conference Proceedings (OSTI)

Symposium, Charles R. Morin Memorial Symposium on Failure Analysis and Prevention. Presentation Title, Intergranular Cracking of Brass Sprinkler Heads.

242

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

243

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

244

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

245

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

246

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

247

Low cutter load raise head  

SciTech Connect

A raise head having a multiplicity of cutters for enlarging a pilot hole into a larger diameter hole by disintegrating the earth formations that surround the pilot hole is provided that will require lower cutter loads to penetrate the formations being bored by directing the rock fracture planes toward the pilot hole forcing the rock to yield with less input energy. The cutters are positioned on the raise head to provide an earth formation contact profile with a major portion of said earth formation contact profile extending outward and upward from said pilot hole. The included angle between the major portion of the earth formation contact profile and the axis of the pilot hole is less than 90/sup 0/.

Saxman, W.C.

1981-03-31T23:59:59.000Z

248

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

249

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

250

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

251

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

252

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

253

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

254

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...

255

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

256

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

257

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

258

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

259

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

260

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

Note: This page contains sample records for the topic "flame retention head" 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

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

262

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

263

In-vessel coolability and retention of a core melt. Volume 2  

Science Conference Proceedings (OSTI)

The efficacy of external flooding of a reactor vessel as a severe accident management strategy is assessed for an AP600-like reactor design. The overall approach is based on the Risk Oriented Accident Analysis Methodology (ROAAM), and the assessment includes consideration of bounding scenarios and sensitivity studies, as well as arbitrary parametric evaluations that allow the delineation of the failure boundaries. Quantification of the input parameters is carried out for an AP600-like design, and the results of the assessment demonstrate that lower head failure is physically unreasonable. Use of this conclusion for any specific application is subject to verifying the required reliability of the depressurization and cavity-flooding systems, and to showing the appropriateness (in relation to the database presented here, or by further testing as necessary) of the thermal insulation design and of the external surface properties of the lower head, including any applicable coatings. The AP600 is particularly favorable to in-vessel retention. Some ideas to enhance the assessment basis as well as performance in this respect, for applications to larger and/or higher power density reactors are also provided.

Theofanous, T.G.; Liu, C.; Additon, S.; Angelini, S.; Kymaelaeinen, O.; Salmassi, T. [California Univ., Santa Barbara, CA (United States). Center for Risk Studies and Safety

1996-10-01T23:59:59.000Z

264

In-Vessel Retention of Molten Corium: Lessons Learned and Outstanding Issues  

Science Conference Proceedings (OSTI)

In-vessel retention (IVR) of core melt is a key severe accident management strategy adopted by some operating nuclear power plants and proposed for some advanced light water reactors (ALWRs). If there were inadequate cooling during a reactor accident, a significant amount of core material could become molten and relocate to the lower head of the reactor vessel, as happened in the Three Mile Island Unit 2 (TMI-2) accident. If it is possible to ensure that the vessel head remains intact so that relocated core materials are retained within the vessel, the enhanced safety associated with these plants can reduce concerns about containment failure and associated risk. For example, the enhanced safety of the Advanced 600 MWe Pressurized Water Reactor (PWR) designed by Westinghouse (AP600), which relied upon External Reactor Vessel Cooling (ERVC) for IVR, resulted in the U.S. Nuclear Regulatory Commission (US NRC) approving the design without requiring certain conventional features common to existing Light Water Reactors (LWRs). However, it is not clear that the ERVC proposed for the AP600 could provide sufficient heat removal for higher-power reactors (up to 1500 MWe) without additional enhancements. This paper reviews efforts made and results reported regarding the enhancement of IVR in LWRs. Where appropriate, the paper identifies what additional data or analyses are needed to demonstrate that there is sufficient margin for successful IVR in high power thermal reactors.

J.L. Rempe; K.Y. Suh; F. B. Cheung; S. B. Kim

2008-03-01T23:59:59.000Z

265

In-Vessel Retention Technology Development and Use for Advanced PWR Designs in the USA and Korea  

SciTech Connect

In-Vessel Retention (IVR) of molten core debris by means of external reactor vessel flooding is a cornerstone of severe accident management for Westinghouse's AP600 (advanced passive light water reactor) design. The case for its effectiveness (made in previous work by the PI) has been thoroughly documented, reviewed as part of the licensing certification, and accepted by the US Nuclear Regulatory Commission. A successful IVR would terminate a severe accident, passively, with the core in a stable, coolable configuration (within the lower head), thus avoiding the largely uncertain accident evolution with the molten debris on the containment floor. This passive plant design has been upgraded by Westinghouse to the AP1000, a 1000 MWe plant very similar to the AP600. The severe accident management approach is very similar too, including In-Vessel Retention as the cornerstone feature, and initial evaluations indicated that this would be feasible at the higher power as well. A similar strategy is adopted in Korea for the APR1400 plant. The overall goal of this project is to provide experimental data and develop the necessary basic understanding so as to allow the robust extension of the AP600 In-Vessel Retention strategy for severe accident management to higher power reactors, and in particular, to the AP1000 advanced passive design.

T.G. Theofanous; S.J. Oh; J.H. Scobel

2004-05-18T23:59:59.000Z

266

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

267

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

268

An Enhanced In-Vessel Core Catcher for Improving In-Vessel Retention Margins  

SciTech Connect

In-vessel retention (IVR) of core melt that may relocate to the lower head of a reactor vessel is a key severe accident management strategy adopted by some operating nuclear power plants and proposed for several advanced light water reactors. A U.S.-Korean International Nuclear Energy Research Initiative project has been initiated to explore design enhancements that could increase the margin for IVR for advanced reactors with higher power levels [up to 1500 MW(electric)]. As part of this effort, an enhanced in-vessel core catcher is being designed and evaluated. To reduce cost and simplify manufacture and installation, this new core catcher design consists of several interlocking sections that are machined to fit together when inserted into the lower head. If needed, the core catcher can be manufactured with holes to accommodate lower head penetrations. Each section of the core catcher consists of two material layers with an option to add a third layer (if deemed necessary). The first is a base material that has the capability to support and contain the mass of core materials that may relocate during a severe accident; the second is an oxide coating on top of the base material, which resists interactions with high-temperature core materials; and the third is an optional coating on the bottom side of the base material to protect it from oxidation during the lifetime of the reactor. This paper summarizes results from the invessel core catcher design and evaluation efforts, focusing on recently obtained results from materials interaction tests and prototypic testing activities.

Joy L. Rempe

2005-11-01T23:59:59.000Z

269

Development of an Enhanced Core Catcher for Improving In-Vessel Retention Margins  

Science Conference Proceedings (OSTI)

In-vessel retention (IVR) of core melt that may relocate to the lower head of a reactor vessel is a key severe accident management strategy adopted by some operating nuclear power plants and proposed for several advanced light water reactors. A U.S.-Korean International Nuclear Energy Research Initiative project has been initiated to explore design enhancements that could increase the margin for IVR for advanced reactors with higher power levels [up to 1500 MW(electric)]. As part of this effort, an enhanced in-vessel core catcher is being designed and evaluated. To reduce cost and simplify manufacture and installation, this new core catcher design consists of several interlocking sections that are machined to fit together when inserted into the lower head. If needed, the core catcher can be manufactured with holes to accommodate lower head penetrations. Each section of the core catcher consists of two material layers with an option to add a third layer (if deemed necessary). The first is a base material that has the capability to support and contain the mass of core materials that may relocate during a severe accident; the second is an oxide coating on top of the base material, which resists interactions with high-temperature core materials; and the third is an optional coating on the bottom side of the base material to protect it from oxidation during the lifetime of the reactor. This paper summarizes results from the in-vessel core catcher design and evaluation efforts, focusing on recently obtained results from materials interaction tests and prototypic testing activities.

Rempe, J.L. [Idaho National Engineering and Environmental Laboratory (United States); Condie, K.G. [Idaho National Engineering and Environmental Laboratory (United States); Knudson, D.L. [Idaho National Engineering and Environmental Laboratory (United States); Suh, K.Y. [Seoul National University (Korea, Republic of); Cheung, F.B. [The Pennsylvania State University (United States); Kim, S.B. [Korea Atomic Energy Research Institute (Korea, Republic of)

2005-11-15T23:59:59.000Z

270

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

271

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

272

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

273

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...

274

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.

275

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

276

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

277

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

278

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

279

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

280

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 retention head" 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

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

282

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

283

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

284

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

285

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

286

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

287

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

288

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

289

July 2012, Work Force Retention Work Group Status Overview  

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

Work Force Retention Work Group Status Overview Work Force Retention Work Group Status Overview Accomplishments: 1. Progress on the completion of the 10 CFR 1046 modifications to address barriers to workforce retention. Written response to public comment is being drafted by HS-51. 2. Pro-Force (PF) union representative, Randy Lawson, identified this accomplishment as the single most significant step toward PF workforce retention in over 20 years. 3. Draft re-charter of PF Career Options Committee (PFCOC) to establish a PF Working Group approved by GC-63 and GC NNSA. Near Term Goals and Activities: 1. Publish 1046 as a final rule - anticipated completion no later than September, assuming timely OMB review and approval. 2. Draft PF Working Group charter final review by senior management to be

290

September 2012, Work Force Retention Work Group Status Overview  

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

Work Force Retention Work Group Status Overview Work Force Retention Work Group Status Overview 2 Subgroups: Pro-Force and Non-Pro-Force Pro-Force Subgroup: Accomplishments: 1. Completion of 10 CFR 1046 [Protective Force Personnel Medical, Physical Readiness, Training, and Access Authorization Standards] as a final rule that includes modification efforts to address barriers to workforce retention. 2. Pro-Force (PF) union representative, Randy Lawson, identified this accomplishment as the single most significant step toward PF workforce retention in over 20 years. 3. Draft re-charter of PF Career Options Committee (PFCOC) to establish a PF Working Group approved by GC-63 and GC NNSA. Near Term Goals and Activities: 1. Publish 1046 as a final rule - publication anticipated this month.

291

The Influence of Land Surface Moisture Retention on Precipitation Statistics  

Science Conference Proceedings (OSTI)

The retention of precipitation water in land surface reservoirs damps higher frequencies of evaporation variability and can thereby influence the feedback of evaporation on precipitation. The extent of this influence is examined in a series of ...

Randal D. Koster; Max J. Suarez

1996-10-01T23:59:59.000Z

292

Failure Analysis of a Reciprocating Compressor Head  

Science Conference Proceedings (OSTI)

Abstract Scope, A major oil company operation experienced a reciprocating compressor failure on one of its offshore platforms. The compressor head on the 1st ...

293

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

294

Bubble retention in synthetic sludge: Testing of alternative gas retention apparatus  

SciTech Connect

Several of the underground storage tanks currently used to store waste at Hanford have been placed on the Flammable Gas Watch List, because the waste is either known or suspected to generate, store, and episodically release flammable gases. The objective of this experimental study is to develop a method to measure gas bubble retention in simulated tank waste and in diluted simulant. The method and apparatus should (1) allow for reasonably rapid experiments, (2) minimize sample disturbance, and (3) provide realistic bubble nucleation and growth. The scope of this experimental study is to build an apparatus for measuring gas retention in simulated waste and to design the apparatus to be compatible with future testing on actual waste. The approach employed for creating bubbles in sludge involves dissolving a soluble gas into the supernatant liquid at an elevated pressure, recirculating the liquid containing the dissolved gas through the sludge, then reducing the pressure to allow bubbles to nucleate and grow. Results have been obtained for ammonia as the soluble gas and SY1-SIM-91A, a chemically representative simulated tank waste. In addition, proof-of-principle experiments were conducted with both ammonia and CO{sub 2} as soluble gases and sludge composed of 90-micron glass beads. Results are described.

Rassat, S.D.; Gauglitz, P.A.

1995-07-01T23:59:59.000Z

295

HeadLock : wide-range head pose estimation for low resolution video  

E-Print Network (OSTI)

This thesis focuses on data mining technologies to extract head pose information from low resolution video recordings. Head pose, as an approximation of gaze direction, is a key indicator of human behavior and interaction. ...

DeCamp, Philip (Philip James)

2008-01-01T23:59:59.000Z

296

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

297

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

298

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

299

Automatic Interpretation of Human Head Movements  

E-Print Network (OSTI)

This paper describes a complete face tracking system that interprets human head movements in real time. The system combines motion analysis with reliable and efficient object recognition strategies. It classifies head movements as "yes" (nodding head), "no" (shaking head) or "nothing" (still head). The system's skill allows contactless man-machine interaction, thus giving access to a number of new applications. 1 Introduction As industrialization proceeds, the importance of interactions between man and machine increases rapidly. Information flow from machine to man has become comfortable and direct in recent years due to tremendous progresses in computer graphics. Information flow from man to machine, on the other hand, is still on a low level. It is restricted to moving mice, pressing buttons, and typing character sequences on a keyboard. Automatic interpretation of gestures and facial expressions could reduce this imbalance and is therefore of central interrest for current and futu...

Bichsel Pentland; M. Bichsel; A. P. Pentland

1993-01-01T23:59:59.000Z

300

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

Note: This page contains sample records for the topic "flame retention head" 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

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

302

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

303

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

304

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

305

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

306

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

307

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

308

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

309

SUBJECT: Guidance on Retention of Facility Representative Technical  

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

SUBJECT: Guidance on Retention of Facility Representative Technical SUBJECT: Guidance on Retention of Facility Representative Technical Competence during Reductions in Force, 4/21/1998 SUBJECT: Guidance on Retention of Facility Representative Technical Competence during Reductions in Force, 4/21/1998 The Department's Revised Implementation Plan (IP) for Defense Nuclear Facilities Safety Board Recommendation 93-3 renews the Department's commitment to maintaining the technical capability necessary to safely manage and operate defense nuclear facilities. Retaining highly qualified employees in critical technical skills areas is vital to the maintenance of these technical capabilities. The Department has therefore committed in the revised R? to the development of a model that offices can use to proactively manage and preserve critical technical capabilities. During the

310

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

311

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

312

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

313

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

314

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

315

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

316

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

317

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

318

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

319

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

320

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

Note: This page contains sample records for the topic "flame retention head" from the National Library of EnergyBeta (NLEBeta).
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they are not comprehensive nor are they the most current set.
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321

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

322

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

323

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

324

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

325

The Flicker and the Red Headed Woodpecker  

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

Smaller than the flicker, it is the only woodpecker with the entire head and neck red -- a bright scarlet. The breast is white; the back bluish- black with a big square...

326

Vacuum compatible miniature CCD camera head  

DOE Patents (OSTI)

A charge-coupled device (CCD) camera head which can replace film for digital imaging of visible light, ultraviolet radiation, and soft to penetrating x-rays, such as within a target chamber where laser produced plasmas are studied. The camera head is small, capable of operating both in and out of a vacuum environment, and is versatile. The CCD camera head uses PC boards with an internal heat sink connected to the chassis for heat dissipation, which allows for close(0.04" for example) stacking of the PC boards. Integration of this CCD camera head into existing instrumentation provides a substantial enhancement of diagnostic capabilities for studying high energy density plasmas, for a variety of military industrial, and medical imaging applications.

Conder, Alan D. (Tracy, CA)

2000-01-01T23:59:59.000Z

327

Heater head for a Stirling engine  

Science Conference Proceedings (OSTI)

A heater head is described for a compound Stirling engine modules, each including a displacer cylinder coaxially aligned with the displacer cylinder of the other of the engine modules, a displacer piston mounted for reciprocation in the displacer cylinder.

Darooka, D.K.

1988-09-06T23:59:59.000Z

328

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

329

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

330

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

331

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

332

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

333

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

334

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

335

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

336

Electro-optic voltage sensor head  

DOE Patents (OSTI)

The invention is an electro-optic voltage sensor head designed for integration with existing types of high voltage transmission and distribution apparatus. The sensor head contains a transducer, which comprises a transducing material in which the Pockels electro-optic effect is observed. In the practice of the invention at least one beam of electromagnetic radiation is routed into the transducing material of the transducer in the sensor head. The beam undergoes an electro-optic effect in the sensor head when the transducing material is subjected to an E-field. The electro-optic effect is observed as a differential phase a shift, also called differential phase modulation, of the beam components in orthogonal planes of the electromagnetic radiation. In the preferred embodiment the beam is routed through the transducer along an initial axis and then reflected by a retro-reflector back substantially parallel to the initial axis, making a double pass through the transducer for increased measurement sensitivity. The preferred embodiment of the sensor head also includes a polarization state rotator and at least one beam splitter for orienting the beam along major and minor axes and for splitting the beam components into two signals which are independent converse amplitude-modulated signals carrying E-field magnitude and hence voltage information from the sensor head by way of optic fibers.

Crawford, Thomas M. (Idaho Falls, ID); Davidson, James R. (Idaho Falls, ID); Woods, Gregory K. (Cornelius, OR)

1999-01-01T23:59:59.000Z

337

Electro-optic voltage sensor head  

DOE Patents (OSTI)

The invention is an electro-optic voltage sensor head designed for integration with existing types of high voltage transmission and distribution apparatus. The sensor head contains a transducer, which comprises a transducing material in which the Pockels electro-optic effect is observed. In the practice of the invention at least one beam of electromagnetic radiation is routed into the transducing material of the transducer in the sensor head. The beam undergoes an electro-optic effect in the sensor head when the transducing material is subjected to an E-field. The electro-optic effect is observed as a differential phase a shift, also called differential phase modulation, of the beam components in orthogonal planes of the electromagnetic radiation. In the preferred embodiment the beam is routed through the transducer along an initial axis and then reflected by a retro-reflector back substantially parallel to the initial axis, making a double pass through the transducer for increased measurement sensitivity. The preferred embodiment of the sensor head also includes a polarization state rotator and at least one beam splitter for orienting the beam along major and minor axes and for splitting the beam components into two signals which are independent converse amplitude-modulated signals carrying E-field magnitude and hence voltage information from the sensor head by way of optic fibers. 6 figs.

Crawford, T.M.; Davidson, J.R.; Woods, G.K.

1999-08-17T23:59:59.000Z

338

BitVault: a highly reliable distributed data retention platform  

Science Conference Proceedings (OSTI)

This paper summarizes our experience designing and implementing BitVault: a content-addressable retention platform for large volumes of reference data -- seldom-changing information that needs to be retained for a long time. BitVault uses "smart bricks" ...

Zheng Zhang; Qiao Lian; Shiding Lin; Wei Chen; Yu Chen; Chao Jin

2007-04-01T23:59:59.000Z

339

Efficient audit-based compliance for relational data retention  

Science Conference Proceedings (OSTI)

The Sarbanes-Oxley Act inspired research on long-term high-integrity retention of business records, leveraging the immutability guarantees that WORM storage servers offer for files. In this paper, we present the transaction log on WORM (TLOW) ... Keywords: audit, forensics, regulatory compliance

Ragib Hasan; Marianne Winslett

2011-03-01T23:59:59.000Z

340

Online idea contests: identifying factors for user retention  

Science Conference Proceedings (OSTI)

Current literature about idea contests has emphasized individuals' motives for joining volunteer idea contests. However, explanation of why people stay or leave in the long run is rare. We identify factors that motivate users to participate repeatedly ... Keywords: motivation, multiple idea contests, open innovation, user retention

Stefan Richter, Stefan Perkmann Berger, Giordano Koch, Johann Füller

2013-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "flame retention head" 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

Onderwerpscodes Chemie -Farmacie / Subject headings Chemistry -Pharmacy, 2009, April1 Rubrieken Chemie -Farmacie: Subject headings Chemistry -  

E-Print Network (OSTI)

Onderwerpscodes Chemie - Farmacie / Subject headings Chemistry - Pharmacy, 2009, April1 Rubrieken Chemie - Farmacie: Subject headings Chemistry - Pharmacy Gang . kast - Aisle . bookcase 01 Algemeen 01 chemie 05 Physical chemistry 10.08 - 06 Chemische binding 06 Chemical bonding 10.13 - 07 Anorganische

Galis, Frietson

342

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

343

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

344

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

345

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

346

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 samples with lower Eu doping concentrations, a critical particle diameter was found, whose value increased with increasing Eu doping concentration. Particles well below the critical diameter had the monoclinic structure; those well above the critical diameter had the cubic structure. At sufficiently high Eu doping concentrations, all Y2O3:Eu generated in H2/O2 flames had the monoclinic structure. On the other hand, all particles generated in the H2/air flames had the cubic structure. For the Y2O3:Eu particles generated in H2/O2 flames, XPS results showed that the surface Eu concentration was several times higher than the doping concentration. For Y2O3:Eu particles generated in H2/air flames, the surface Eu concentration was equal to the doping concentration. For both types of particles, the photoluminescence intensity reached a maximum corresponding to a surface Eu concentration 40~50%. The photoluminescence intensity then decreased rapidly with higher Eu doping concentration. The effect of particle size and Eu doping concentration on crystal structure may be explained by the interplay between surface energy and polymorphism. A mechanism for this surface enrichment phenomenon was proposed based on the binary Eu2O3-Y2O3 phase diagram.

Yim, Hoon

2009-05-01T23:59:59.000Z

347

Head assembly for multiposition borehole extensometer  

DOE Patents (OSTI)

A head assembly for a borehole extensometer and an improved extensometer for measuring subsurface subsidence. A plurality of inflatable anchors provide discrete measurement points. A metering rod is fixed to each of the anchors which are displaced when subsidence occurs, thereby translating the attached rod. The head assembly includes a sprocket wheel rotatably mounted on a standpipe and engaged by a chain which is connected at one end to the metering rod and at the other end to a counterweight. A second sprocket wheel connected to the standpipe also engages the chain and drives a connected potentiometer. The head assembly converts the linear displacement of the metering rod to the rotary motion of the second sprocket wheel, which is measured by the potentiometer, producing a continuous electrical output.

Frank, Donald N. (Livermore, CA)

1983-01-01T23:59:59.000Z

348

Head assembly for multiposition borehole extensometer  

DOE Patents (OSTI)

A head assembly for a borehole extensometer and an improved extensometer for measuring subsurface subsidence. A plurality of inflatable anchors provide discrete measurement points. A metering rod is fixed to each of the anchors which are displaced when subsidence occurs, thereby translating the attached rod. The head assembly includes a sprocket wheel rotatably mounted on a standpipe and engaged by a chain which is connected at one end to the metering rod and at the other end to a counterweight. A second sprocket wheel connected to the standpipe also engages the chain and drives a connected potentiometer. The head assembly converts the linear displacement of the metering rod to the rotary motion of the second sprocket wheel, which is measured by the potentiometer, producing a continuous electrical output.

Frank, D.N.

1981-06-09T23:59:59.000Z

349

Characterization of diffusion flames for synthesis of single-walled carbon nanotubes  

Science Conference Proceedings (OSTI)

Recent studies have shown that Fe/Si/O catalysts on the fuel side of an oxygen-enriched inverse diffusion flame produce micron-length single-walled carbon nanotubes at rapid rates (>100{mu}m/s). Despite the favorable catalyst/flame interaction for nanotube nucleation and growth, the catalyst lifetimes are only a few milliseconds. To increase catalyst lifetime and hence, carbon nanotube length, it is necessary to know how the local environment changes as the catalyst moves through the flame. A 2-D computational fluid dynamics model with detailed chemistry is employed to investigate the nature of the flame environment along various catalyst trajectories. The results indicate that temperature and species concentrations do not change significantly along individual catalyst trajectories, although not all trajectories experience the same environment due to the steep gradients in the radial direction. On the other hand, analysis of catalyst particle composition before and after nanotube growth shows that catalyst oxygen content decreases significantly during nanotube growth. This change in catalyst composition could affect the relative rates of carbon supply versus removal from the catalyst surface, such that carbon encapsulation and thus poisoning of the catalyst is favored after sufficient time. The results of this work indicate that catalyst deactivation, not a changing catalyst environment, is responsible for rapid encapsulation of the catalyst by amorphous carbon and thus, the short catalyst lifetimes observed in oxygen-enriched diffusion flames. (author)

Unrau, C.J.; Axelbaum, R.L. [Department of Energy, Environmental, Chemical Engineering/Center for Materials Innovation, Washington University, St. Louis, MO (United States); Katta, V.R. [Innovative Scientific Solutions, Inc., Dayton, OH (United States)

2010-09-15T23:59:59.000Z

350

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

351

Reduction of soot emissions by iron pentacarbonyl in isooctane diffusion flames  

Science Conference Proceedings (OSTI)

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

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

2008-07-15T23:59:59.000Z

352

Asymptotic analysis of stationary adiabatic premixed flames in porous inert media  

Science Conference Proceedings (OSTI)

The structure of adiabatic premixed flames within porous inert media is investigated using the asymptotic expansion method. For this, the flame structure is divided into three characteristic length scales. The two innermost length scales, the gas-phase diffusion length scale and the reaction length scale, are the same scales defined in the classical premixed flame structure analysis. The outermost length scale, the solid-phase diffusion length scale, is related to the heat conduction in the porous matrix. The differences among these three characteristic length-scales result in large temperature differences between the phases and justify the application of asymptotic expansions to determine an approximate (analytical) solution. Since the main focus of this work is the examination of the processes in the outer and the first inner regions, the simplest kinetic mechanism of one global step is adopted to represent the fuel and oxygen consumption. Then, the description of the reaction zone is obtained using the large activation energy asymptotic method. The description of the problem of the order of the gas-phase length scale is obtained using the boundary layer expansion. This work evaluates the influence of the equivalence ratio, the ratio of the solid to the gas thermal conductivities, the porosity of the medium and the fuel Lewis number on such flames. A parameter that universalizes the flame properties is then identified and discussed. (author)

Pereira, Fernando M.; Oliveira, Amir A.M. [Departamento de Engenharia Mecanica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, SC (Brazil); Fachini, Fernando F. [Instituto Nacional de Pesquisas Espaciais, 12630-000 Cachoeira Paulista, SP (Brazil)

2008-11-15T23:59:59.000Z

353

Asymptotic analysis of stationary adiabatic premixed flames in porous inert media  

SciTech Connect

The structure of adiabatic premixed flames within porous inert media is investigated using the asymptotic expansion method. For this, the flame structure is divided into three characteristic length scales. The two innermost length scales, the gas-phase diffusion length scale and the reaction length scale, are the same scales defined in the classical premixed flame structure analysis. The outermost length scale, the solid-phase diffusion length scale, is related to the heat conduction in the porous matrix. The differences among these three characteristic length-scales result in large temperature differences between the phases and justify the application of asymptotic expansions to determine an approximate (analytical) solution. Since the main focus of this work is the examination of the processes in the outer and the first inner regions, the simplest kinetic mechanism of one global step is adopted to represent the fuel and oxygen consumption. Then, the description of the reaction zone is obtained using the large activation energy asymptotic method. The description of the problem of the order of the gas-phase length scale is obtained using the boundary layer expansion. This work evaluates the influence of the equivalence ratio, the ratio of the solid to the gas thermal conductivities, the porosity of the medium and the fuel Lewis number on such flames. A parameter that universalizes the flame properties is then identified and discussed. (author)

Pereira, Fernando M.; Oliveira, Amir A.M. [Departamento de Engenharia Mecanica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, SC (Brazil); Fachini, Fernando F. [Instituto Nacional de Pesquisas Espaciais, 12630-000 Cachoeira Paulista, SP (Brazil)

2009-01-15T23:59:59.000Z

354

Measurements of fuel mixture fraction oscillations of a turbulent jet non-premixed flame  

Science Conference Proceedings (OSTI)

This work describes new type of combustion instability for which the 3-way coupling between mixing, flame heat release, and acoustics is modified by local buoyancy effects. Measurements of fuel mixture fraction are made for a non-premixed jet flame in a combustion chamber to assess the dynamics of mixing under imposed acoustic oscillations (22-55 Hz). Infrared laser absorption and phase resolved acetone-planar laser induced fluorescence are used to measure the fuel mixture fraction and then the degree of fuel/air mixing is calculated by determining the unmixedness. Results show acoustic excitation causes oscillations in the degree of fuel/air mixing at the driving frequency, which results in oscillatory flame behavior. This oscillatory flame behavior couples to the buoyancy and this in turn affects the mixing. Results also show that the mixing becomes less effective when the excitation frequency is increased or when the flame is present, compared to the non-reacting case. This work describes a key coupling mechanism that occurs when buoyancy is a significant factor in the flow field. (author)

Kanga, D.M. [LG Chem Research Park, Dajeon 305-380 (Korea); Fernandez, V.; Culick, F.E.C. [Department of Mechanical Engineering, California Institute of Technology, Pasadena, CA 91125 (United States); Ratner, A. [Department of Mechanical and Industrial Engineering, University of Iowa, Iowa City, IA 52242 (United States)

2009-01-15T23:59:59.000Z

355

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

E-Print Network (OSTI)

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

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

2006-12-18T23:59:59.000Z

356

Slurry growth and gas retention in synthetic Hanford waste  

DOE Green Energy (OSTI)

This work seeks to establish chemical and physical processes responsible for the generation and retention of gases within waste from a particular high-level waste tank on the Hanford Site, Tank 101-SY, through the use of synthetic wastes on a laboratory scale. The goal of these activities is to support the development of mitigation/remediation strategies for Tank 101-SY. Laboratory studies of aged synthetic waste have shown that gas generation occurs thermally at a significant level at current tank temperatures. Gas compositions include the same gases produced in actual tank waste, primarily N{sub 2}, N{sub 2}O, and H{sub 2}. Gas stoichiometries have been shown to be greatly influenced by several organic and inorganic constituents within the synthetic waste. Retention of gases in the synthetic waste is in the form of bubble attachment to solid particles.

Bryan, S.A.; Pederson, L.R.; Scheele, R.D.

1992-09-01T23:59:59.000Z

357

Slurry growth and gas retention in synthetic Hanford waste  

DOE Green Energy (OSTI)

This work seeks to establish chemical and physical processes responsible for the generation and retention of gases within waste from a particular high-level waste tank on the Hanford Site, Tank 101-SY, through the use of synthetic wastes on a laboratory scale. The goal of these activities is to support the development of mitigation/remediation strategies for Tank 101-SY. Laboratory studies of aged synthetic waste have shown that gas generation occurs thermally at a significant level at current tank temperatures. Gas compositions include the same gases produced in actual tank waste, primarily N[sub 2], N[sub 2]O, and H[sub 2]. Gas stoichiometries have been shown to be greatly influenced by several organic and inorganic constituents within the synthetic waste. Retention of gases in the synthetic waste is in the form of bubble attachment to solid particles.

Bryan, S.A.; Pederson, L.R.; Scheele, R.D.

1992-09-01T23:59:59.000Z

358

Plasma wall interaction and tritium retention in TFTR  

SciTech Connect

The Tokamak Fusion Test Reactor (TFTR) has been operating safely and routinely with deuterium-tritium fuel for more than two years. In this time, TFTR has produced an impressive number of record breaking results including core fusion power, {approximately} 2 MW/m{sup 3}, comparable to that expected for ITER. Advances in wall conditioning via lithium pellet injection have played an essential role in achieving these results. Deuterium-tritium operation has also provided a special opportunity to address the issues of tritium recycling and retention. Tritium retention over two years of operation was approximately 40%. Recently, the in-torus tritium inventory was reduced by half through a combination of glow discharge cleaning, moist-air soaks, and plasma discharge cleaning. The tritium inventory is not a constraint in continued operations. The authors present recent results from TFTR in the context of plasma wall interactions and deuterium-tritium issues.

Skinner, C.H.; Amarescu, E.; Ascione, G. [and others

1996-08-01T23:59:59.000Z

359

Average Soil Water Retention Curves Measured by Neutron Radiography  

SciTech Connect

Water retention curves are essential for understanding the hydrologic behavior of partially-saturated porous media and modeling flow transport processes within the vadose zone. In this paper we report direct measurements of the main drying and wetting branches of the average water retention function obtained using 2-dimensional neutron radiography. Flint sand columns were saturated with water and then drained under quasi-equilibrium conditions using a hanging water column setup. Digital images (2048 x 2048 pixels) of the transmitted flux of neutrons were acquired at each imposed matric potential (~10-15 matric potential values per experiment) at the NCNR BT-2 neutron imaging beam line. Volumetric water contents were calculated on a pixel by pixel basis using Beer-Lambert s law after taking into account beam hardening and geometric corrections. To remove scattering effects at high water contents the volumetric water contents were normalized (to give relative saturations) by dividing the drying and wetting sequences of images by the images obtained at saturation and satiation, respectively. The resulting pixel values were then averaged and combined with information on the imposed basal matric potentials to give average water retention curves. The average relative saturations obtained by neutron radiography showed an approximate one-to-one relationship with the average values measured volumetrically using the hanging water column setup. There were no significant differences (at p < 0.05) between the parameters of the van Genuchten equation fitted to the average neutron radiography data and those estimated from replicated hanging water column data. Our results indicate that neutron imaging is a very effective tool for quantifying the average water retention curve.

Cheng, Chu-Lin [ORNL; Perfect, Edmund [University of Tennessee, Knoxville (UTK); Kang, Misun [ORNL; Voisin, Sophie [ORNL; Bilheux, Hassina Z [ORNL; Horita, Juske [Texas Tech University (TTU); Hussey, Dan [NIST Center for Neutron Research (NCRN), Gaithersburg, MD

2011-01-01T23:59:59.000Z

360

ADDITIVE TESTING FOR IMPROVED SULFUR RETENTION: PRELIMINARY REPORT  

SciTech Connect

The Savannah River National Laboratory is collaborating with Alfred University to evaluate the potential for additives in borosilicate glass to improve sulfur retention. This preliminary report provides further background on the incorporation of sulfur in glass and outlines the experiments that are being performed by the collaborators. A simulated waste glass composition has been selected for the experimental studies. The first phase of experimental work will evaluate the impacts of BaO, PbO, and V{sub 2}O{sub 5} at concentrations of 1.0, 2.0, and 5.0 wt % on sulfate retention in simulated high level waste borosilicate glass. The second phase of experimental work will evaluate the effects of time at the melt temperature on sulfur retention. The resulting samples will be characterized to determine the amount of sulfur remaining as well as to identify the formation of any crystalline phases. The results will be used to guide the future selection of frits and glass forming chemicals in vitrifying Department of Energy wastes containing high sulfur concentrations.

Amoroso, J.; Fox, K.

2011-09-07T23:59:59.000Z

Note: This page contains sample records for the topic "flame retention head" 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

Effects of buoyancy on lean premixed v-flames, Part II. VelocityStatistics in Normal and Microgravity  

Science Conference Proceedings (OSTI)

The field effects of buoyancy on laminar and turbulent premixed v-flames have been studied by the use of laser Doppler velocimetry to measure the velocity statistics in +1g, -1g and {micro}g flames. The experimental conditions covered mean velocity, Uo, of 0.4 to 2 m/s, methane/air equivalence ratio, f, of 0.62 to 0.75. The Reynolds numbers, from 625 to 3130 and the Richardson number from 0.05 to 1.34. The results show that a change from favorable (+1g) to unfavorable (-1g) mean pressure gradient in the plume create stagnating flows in the far field whose influences on the mean and fluctuating velocities persist in the near field even at the highest Re we have investigated. The use of Richardson number flames are direct consequences of buoyancy. Furthermore, the rms fluctuations in the plumes of {micro}g flames are lower and more isotropic than in the laboratory flames to show that the unstable plumes in laboratory flames also induce velocity fluctuations. The phenomena influenced by buoyancy i.e. degree of flame wrinkling, flow acceleration, flow distribution, and turbulence production, can be subtle due to their close coupling with other flame flow interaction processes. But they cannot be ignored in fundamental studies or else the conclusions and insights would be ambiguous and not very meaningful.

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

1999-07-01T23:59:59.000Z

362

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

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

Experimental Endeavour on a Pillar of Flame: Space Shuttle Rises Experimental Endeavour on a Pillar of Flame: Space Shuttle Rises with Ambitious Technology Aboard Experimental Endeavour on a Pillar of Flame: Space Shuttle Rises with Ambitious Technology Aboard May 17, 2011 - 5:15pm Addthis Smoke cloud from Endeavour's Final Launge | Photo: NASA, Troy Cryder Smoke cloud from Endeavour's Final Launge | Photo: NASA, Troy Cryder Charles Rousseaux Charles Rousseaux Senior Writer, Office of Science What are the key facts? Space Shuttle Endeavour, which lifted off on its final mission Monday, carrying the Alpha Magnetic Spectrometer (AMS) experiment. In addition to measuring how cosmic rays flow and what they are made of, the AMS will also search for cosmic rays made of a special form of matter known as antimatter. By looking for new particles in space via the AMS, scientists might

363

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

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

Experimental Endeavour on a Pillar of Flame: Space Shuttle Rises Experimental Endeavour on a Pillar of Flame: Space Shuttle Rises with Ambitious Technology Aboard Experimental Endeavour on a Pillar of Flame: Space Shuttle Rises with Ambitious Technology Aboard May 17, 2011 - 5:15pm Addthis Smoke cloud from Endeavour's Final Launge | Photo: NASA, Troy Cryder Smoke cloud from Endeavour's Final Launge | Photo: NASA, Troy Cryder Charles Rousseaux Charles Rousseaux Senior Writer, Office of Science What are the key facts? Space Shuttle Endeavour, which lifted off on its final mission Monday, carrying the Alpha Magnetic Spectrometer (AMS) experiment. In addition to measuring how cosmic rays flow and what they are made of, the AMS will also search for cosmic rays made of a special form of matter known as antimatter. By looking for new particles in space via the AMS, scientists might

364

Influence of transport phenomena on the structure of lean premixed hydrogen air flames  

Science Conference Proceedings (OSTI)

Because of hydrogen release during a hypothetical severe accident in a light water reactor, an intense investigation of premixed hydrogen-air combustion and connected safety aspects is being conducted. Hydrogen combustion in the course of a gradual hydrogen release normally starts out from slow deflagrations, which, however, can be accelerated to very high flame speeds by flame-obstacle interaction yielding a complex superimposition of chemical kinetics and turbulent heat and mass transfer. Numerical models for the turbulent burning rate rely mainly on the assumption of continuous wrinkled or corrugated flame fronts, which are stretched or quenched, respectively, by flow strain and small-scale fluctuations. Considerable deviations in calculated burning rates point at physical mechanisms that are not yet satisfactorily understood.

Ardey, N.; Mayinger, F.; Durst, B. [Technical Univ., Munich (Germany)

1995-12-31T23:59:59.000Z

365

Moisture Retention Curves of Topopah Spring Tuff at Elevated Temperatures  

SciTech Connect

Knowledge of unsaturated flow and transport in porous media is critical for understanding the movement of water and solute through the unsaturated zone. The suction potential of rock determines the imbibition of water and, therefore, the moisture retention in the matrix. That, in turn, affects the relative importance of matrix flow and fracture flow, and their interaction, because greater suction potential moves more water from fractures into the matrix and therefore retards fracture flow. The moisture content as a function of the suction potential is called a moisture retention curve or a characteristic curve. Moisture-retention data are important input for numerical models of water movement in unsaturated porous media. Also important are the effect of sample history on the moisture-retention curves and whether there is significant hysteresis between wetting and drying measurements. The Yucca Mountain Site Characterization Project (YMP) of the U.S. Department of Energy is studying the suitability of the tuffaceous rock at Yucca Mountain, Nevada, for a potential high-level nuclear waste repository. The potential repository horizon will be in the unsaturated zone of the Topopah Spring member (densely welded) of the Paintbrush Tuff unit at Yucca Mountain. This unit is highly fractured. Therefore, transport of water within the near field of the nuclear waste package in the repository is strongly influenced by the suction potential of the repository host rocks at elevated temperatures. In a high-level nuclear waste repository, the rock mass around the waste packages will become dry because of the thermal load of the waste but will then re-wet during the cool-down period as the thermal output of the waste packages declines. Much of this process will occur at temperatures above ambient temperature. The goal of our work is to determine the importance of temperature and the wetting-drying hysteresis on the measured moisture retention curves of the densely welded tuff. For Topopah Spring tuff the suction potential is assumed to be primary due to the matric potential.

Lin, W.; Roberts, J.; Carlberg, E.; Ruddle, D.; Pletcher, R.

2001-11-30T23:59:59.000Z

366

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

Science Conference Proceedings (OSTI)

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

Murat Altay, H.; Hudgins, Duane E.; Speth, Raymond L.; Annaswamy, Anuradha M.; Ghoniem, Ahmed F. [Massachusetts Institute of Technology, Department of Mechanical Engineering, Cambridge, MA 02139 (United States)

2010-04-15T23:59:59.000Z

367

A combustion-monitoring system with 3-D temperature reconstruction based on flame-image processing technique  

Science Conference Proceedings (OSTI)

Based on a flame-image processing technology, a real-time combustion-monitoring, system with 3-D temperature reconstruction and visualization installed in a coal-fired furnace of a power plant was reported. A dozen flame detectors with charge-couple-device cameras were mounted along the height of the furnace to capture multiple digital flame images. A radiation energy signal (RES) was obtained from the flame images according to Wien's law of radiation. A series of in situ experiments have been done, and the results showed that the flame temperature distribution and the RES are sensitive to change in the combustion of the boiler and can be used to improve the combustion control in practical application.

Luo, Z.X.; Zhou, H.C. [Huazhong University of Science & Technology, Wuhan (China). School of Energy & Power Engineering

2007-10-15T23:59:59.000Z

368

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

DOE Green Energy (OSTI)

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

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

1996-10-01T23:59:59.000Z

369

Numerical simulation of the laminar diffusion flame in a simplified burner. Revision 1  

DOE Green Energy (OSTI)

The laminar ethylene-air diffusion flame in a simple laboratory burner was simulated with the COYOTE reactive flow program. This program predicts the flow field, transport, and chemistry for the purposes of code validation and providing physical understanding of the processes occurring in the flame. The authors show the results of numerical experiments to test the importance of several physical phenomena, including gravity, radiation, and differential diffusion. The computational results compare favorably with the experimental measurements, and all three phenomena are important to accurate simulations.

Cloutman, L.D.

1996-02-01T23:59:59.000Z

370

Method for producing flame retardant porous products and products produced thereby  

DOE Patents (OSTI)

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

Salyer, I.O.

1998-08-04T23:59:59.000Z

371

Method for producing flame retardant porous products and products produced thereby  

DOE Green Energy (OSTI)

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

Salyer, Ival O. (Dayton, OH)

1998-08-04T23:59:59.000Z

372

Method for Producing Flame Retardant Porous Products and Products Produced Thereby  

DOE Patents (OSTI)

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

Salyer, Ival O. (Dayton, OH)

1998-08-04T23:59:59.000Z

373

In-Vessel Retention of Molten Core Debris in the Westinghouse AP1000 Advanced Passive PWR  

SciTech Connect

In-vessel retention (IVR) of molten core debris via external reactor vessel cooling is the hallmark of the severe accident management strategies in the AP600 passive PWR. The vessel is submerged in water to cool its external surface via nucleate boiling heat transfer. An engineered flow path through the reactor vessel insulation provides cooling water to the vessel surface and vents steam to promote IVR. For the 600 MWe passive plant, the predicted heat load from molten debris to the lower head wall has a large margin to the critical heat flux on the external surface of the vessel, which is the upper limit of the cooling capability. Up-rating the power of the passive plant from 600 to 1000 MWe (AP1000) significantly increases the heat loading from the molten debris to the reactor vessel lower head in the postulated bounding severe accident sequence. To maintain a large margin to the coolability limit for the AP1000, design features and severe accident management (SAM) strategies to increase the critical heat flux on the external surface of the vessel wall need to be implemented. A test program at the ULPU facility at University of California Santa Barbara (UCSB) has been initiated to investigate design features and SAM strategies that can enhance the critical heat flux. Results from ULPU Configuration IV demonstrate that with small changes to the ex-vessel design and SAM strategies, the peak critical heat flux in the AP1000 can be increased at least 30% over the peak critical heat flux predicted for the AP600 configuration. The design and SAM strategy changes investigated in ULPU Configuration IV can be implemented in the AP1000 design and will allow the passive plant to maintain the margin to critical heat flux for IVR, even at the higher power level. Continued testing for IVR phenomena is being performed at UCSB to optimize the AP1000 design and to ensure that vessel failure in a severe accident is physically unreasonable. (authors)

Scobel, James H.; Conway, L.E. [Westinghouse Electric Company LLC, P.O. Box 355, Pittsburgh, PA 15230-0355 (United States); Theofanous, T.G. [Center for Risk Studies and Safety, University of California Santa Barbara (United States)

2002-07-01T23:59:59.000Z

374

A numerical study of transient ignition and flame characteristics of diluted hydrogen versus heated air in counterflow  

Science Conference Proceedings (OSTI)

Combined experimental and numerical studies of the transient response of ignition to strained flows require a well-characterized ignition trigger. Laser deposition of a small radical pool provides a reliable method for initiating ignition of mixtures that are near the ignition limit. Two-dimensional direct numerical simulations are used to quantify the sensitivity of ignition kernel formation and subsequent edge-flame propagation to the oxidizer temperature and the initial width and amplitude of O-atom deposition used to trigger ignition in an axisymmetric counterflow of heated air versus ambient hydrogen/nitrogen. The ignition delay and super-equilibrium OH concentration in the nascent ignition kernel are highly sensitive to variations in these initial conditions. The ignition delay decreases as the amplitude of the initial O-atom deposition increases. The spatial distribution and the magnitude of the OH overshoot are governed by multi-dimensional effects. The degree of OH overshoot near the burner centerline increases as the diameter of the initial O-atom deposition region decreases. This result is attributed to preferential diffusion of hydrogen in the highly curved leading portion of the edge flame that is established following thermal runaway. The edge-flame speed and OH overshoot at the leading edge of the edge flame are relatively insensitive to variations in the initial conditions of the ignition. The steady edge-flame speed is approximately twice the corresponding laminar flame speed. The rate at which the edge flame approaches its steady state is insensitive to the initial conditions and depends solely on the diffusion time scale at the edge flame. The edge flame is curved toward the heated oxidizer stream as a result of differences in the chemical kinetics between the leading edge and the trailing diffusion flame. The structure of the highly diluted diffusion flame considered in this study corresponds to Linan's 'premixed flame regime' in which only the oxidizer leaks through the reaction zone such that the flame is located at fuel lean rather than stoichiometric mixture fraction conditions. (author)

Yoo, Chun Sang; Chen, Jacqueline H. [Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551-0969 (United States); Frank, Jonathan H.

2009-01-15T23:59:59.000Z

375

A numerical study of transient ignition and flame characteristics of diluted hydrogen versus heated air in counterflow  

Science Conference Proceedings (OSTI)

Combined experimental and numerical studies of the transient response of ignition to strained flows require a well-characterized ignition trigger. Laser deposition of a small radical pool provides a reliable method for initiating ignition of mixtures that are near the ignition limit. Two-dimensional direct numerical simulations are used to quantify the sensitivity of ignition kernel formation and subsequent edge-flame propagation to the oxidizer temperature and the initial width and amplitude of O-atom deposition used to trigger ignition in an axisymmetric counterflow of heated air versus ambient hydrogen/nitrogen. The ignition delay and super-equilibrium OH concentration in the nascent ignition kernel are highly sensitive to variations in these initial conditions. The ignition delay decreases as the amplitude of the initial O-atom deposition increases. The spatial distribution and the magnitude of the OH overshoot are governed by multi-dimensional effects. The degree of OH overshoot near the burner centerline increases as the diameter of the initial O-atom deposition region decreases. This result is attributed to preferential diffusion of hydrogen in the highly curved leading portion of the edge flame that is established following thermal runaway. The edge-flame speed and OH overshoot at the leading edge of the edge flame are relatively insensitive to variations in the initial conditions of the ignition. The steady edge-flame speed is approximately twice the corresponding laminar flame speed. The rate at which the edge flame approaches its steady state is insensitive to the initial conditions and depends solely on the diffusion time scale at the edge flame. The edge flame is curved toward the heated oxidizer stream as a result of differences in the chemical kinetics between the leading edge and the trailing diffusion flame. The structure of the highly diluted diffusion flame considered in this study corresponds to Linan's 'premixed flame regime' in which only the oxidizer leaks through the reaction zone such that the flame is located at fuel lean rather than stoichiometric mixture fraction conditions. (author)

Yoo, Chun Sang; Chen, Jacqueline H.; Frank, Jonathan H. [Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551-0969 (United States)

2008-11-15T23:59:59.000Z

376

A numerical study of transient ignition and flame characteristics of diluted hydrogen versus heated air in counterflow.  

SciTech Connect

Combined experimental and numerical studies of the transient response of ignition to strained flows require a well-characterized ignition trigger. Laser deposition of a small radical pool provides a reliable method for initiating ignition of mixtures that are near the ignition limit. Two-dimensional direct numerical simulations are used to quantify the sensitivity of ignition kernel formation and subsequent edge-flame propagation to the oxidizer temperature and the initial width and amplitude of O-atom deposition used to trigger ignition in an axisymmetric counterflow of heated air versus ambient hydrogen/nitrogen. The ignition delay and super-equilibrium OH concentration in the nascent ignition kernel are highly sensitive to variations in these initial conditions. The ignition delay decreases as the amplitude of the initial O-atom deposition increases. The spatial distribution and the magnitude of the OH overshoot are governed by multi-dimensional effects. The degree of OH overshoot near the burner centerline increases as the diameter of the initial O-atom deposition region decreases. This result is attributed to preferential diffusion of hydrogen in the highly curved leading portion of the edge flame that is established following thermal runaway. The edge-flame speed and OH overshoot at the leading edge of the edge flame are relatively insensitive to variations in the initial conditions of the ignition. The steady edge-flame speed is approximately twice the corresponding laminar flame speed. The rate at which the edge flame approaches its steady state is insensitive to the initial conditions and depends solely on the diffusion time scale at the edge flame. The edge flame is curved toward the heated oxidizer stream as a result of differences in the chemical kinetics between the leading edge and the trailing diffusion flame. The structure of the highly diluted diffusion flame considered in this study corresponds to Linan's 'premixed flame regime' in which only the oxidizer leaks through the reaction zone such that the flame is located at fuel lean rather than stoichiometric mixture fraction conditions.

Yoo, Chun Sang; Chen, Jacqueline H.; Frank, Jonathan H.

2008-08-01T23:59:59.000Z

377

Reliable forward walking parameters from head-track data alone  

Science Conference Proceedings (OSTI)

Head motion during real walking is complex: The basic translational path is obscured by head bobbing. Many VE applications would be improved if a bobbing-free path were available. This paper introduces a model that describes head position while walking ...

Jeremy D. Wendt; Mary C. Whitton; David Adalsteinsson; Frederick P. Brooks

2012-03-01T23:59:59.000Z

378

Head Orientation and Gaze Direction in Meetings Rainer Stiefelhagen  

E-Print Network (OSTI)

Head Orientation and Gaze Direction in Meetings Rainer Stiefelhagen Interactive Systems factors in the formation of where a person is looking at : head orientation and eye orientation. In this poster, we present an experiment aimed at evaluating the potential of head orientation estimation

379

A Particle-Water Based Model for Water Retention Hysteresis  

E-Print Network (OSTI)

A particle-water discrete element-based approach to describe water movement in partially saturated granular media is presented and tested. Water potential is governed by both capillary bridges, dominant at low saturations, and pressure of entrapped air, dominant at high saturations. The approach captures the hysteresis of water retention during wetting and drainage by introducing local evolution of liquid-solid contact angles at the level of pores and grains. Next, extensive comparisons against experimental data are presented. While this is made without involving any fitting parameters, the method demonstrates relative high success by achieving a correlation coefficient of at least 82%, and mostly above 90%.

Yixiang Gan; Federico Maggi; Giuseppe Buscarnera; Itai Einav

2013-07-20T23:59:59.000Z

380

MEMORANDUM FOR HEADS OF DEPARTMENTAL ELEMENTS FROM:  

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

HEADS OF DEPARTMENTAL ELEMENTS HEADS OF DEPARTMENTAL ELEMENTS FROM: SUBJECT: Project Full Funding Policy in the Annual ~ u d ~ e t Request On July 18,2008, the Secretary approved the Department's Contract and Project Management Root Cause Analysis (RCA) Corrective Action Plan (CAP). This is the Department's plan to improve contract and project management and ultimately be removed from GAO's High Risk List - a list that the Department has been on since 1990. One of the key issues identified in the CAP is the Department's failure to request and obtain full funding for non-information technology capital asset projects, where appropriate. This new policy is established to reduce the inherent inefficiencies and risks ingoduced by prolonging the duration of small projects, as well as to add budget stability

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381

Surface treatment of magnetic recording heads  

DOE Patents (OSTI)

Surface modification of magnetic recording heads using plasma immersion ion implantation and deposition is disclosed. This method may be carried out using a vacuum arc deposition system with a metallic or carbon cathode. By operating a plasma gun in a long-pulse mode and biasing the substrate holder with short pulses of a high negative voltage, direct ion implantation, recoil implantation, and surface deposition are combined to modify the near-surface regions of the head or substrate in processing times which may be less than 5 min. The modified regions are atomically mixed into the substrate. This surface modification improves the surface smoothness and hardness and enhances the tribological characteristics under conditions of contact-start-stop and continuous sliding. These results are obtained while maintaining original tolerances.

Komvopoulos, Kyriakos (Orinda, CA); Brown, Ian G. (Berkeley, CA); Wei, Bo (Albany, CA); Anders, Simone (Albany, CA); Anders, Andre (Albany, CA); Bhatia, Singh C. (Morgan Hill, CA)

1995-01-01T23:59:59.000Z

382

Surface treatment of magnetic recording heads  

DOE Patents (OSTI)

Surface modification of magnetic recording heads using plasma immersion ion implantation and deposition is disclosed. This method may be carried out using a vacuum arc deposition system with a metallic or carbon cathode. By operating a plasma gun in a long-pulse mode and biasing the substrate holder with short pulses of a high negative voltage, direct ion implantation, recoil implantation, and surface deposition are combined to modify the near-surface regions of the head or substrate in processing times which may be less than 5 min. The modified regions are atomically mixed into the substrate. This surface modification improves the surface smoothness and hardness and enhances the tribological characteristics under conditions of contact-start-stop and continuous sliding. These results are obtained while maintaining original tolerances. 15 figs.

Komvopoulos, K.; Brown, I.G.; Wei, B.; Anders, S.; Anders, A.; Bhatia, S.C.

1995-12-19T23:59:59.000Z

383

Vapor generator steam drum spray head  

DOE Patents (OSTI)

A typical embodiment of the invention provides a combination feedwater and "cooldown" water spray head that is centrally disposed in the lower portion of a nuclear power plant steam drum. This structure not only discharges the feedwater in the hottest part of the steam drum, but also increases the time required for the feedwater to reach the steam drum shell, thereby further increasing the feedwater temperature before it contacts the shell surface, thus reducing thermal shock to the steam drum structure.

Fasnacht, Jr., Floyd A. (Massillon, OH)

1978-07-18T23:59:59.000Z

384

Simulation Analysis of Within-Day Flow Fluctuation Effects on Trout below Flaming Gorge Dam  

Science Conference Proceedings (OSTI)

This report demonstrates the use of an individual-based model for studying the impact of river flow fluctuations resulting from hydroelectric project operation on a tailwater trout fishery. The study was conducted at the Flaming Gorge Hydroelectric Project on the Green River in Utah.

2006-04-20T23:59:59.000Z

385

Combustion and Flame 144 (2006) 662674 www.elsevier.com/locate/combustflame  

E-Print Network (OSTI)

used in missile applications and in many combustion re- search studies [1­15]. It is chiefly composedCombustion and Flame 144 (2006) 662­674 www.elsevier.com/locate/combustflame Thermal decomposition The Combustion Institute. Published by Elsevier Inc. All rights reserved. Keywords: JP-10; Pyrolysis; Kinetics

Anderson, Scott L.

386

Combustion and Flame 142 (2005) 329347 www.elsevier.com/locate/combustflame  

E-Print Network (OSTI)

Combustion and Flame 142 (2005) 329­347 www.elsevier.com/locate/combustflame Large-eddy simulation to generate optimized clustering for variable density combustion simulations. A methane­hydrogen fuel algorithms and subfilter models. The combustion chemistry is described using a precomputed, laminar flamelet

Raman, Venkat

387

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

E-Print Network (OSTI)

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

Im, Hong G.

388

9th Annual North American Waste to Energy Conference USING FLAME QUENCHING TO REDUCE  

E-Print Network (OSTI)

; · Reductions in NOx by lowering flame temperature; and , · The generation of new revenues by utilizing for NOx reduction include load reduction, excess air reduction, stage firing, chemical injection (urea; · Reductions in combustion velocities and tube erosion rate; · Reductions in thermal NOx by loweringflame

Columbia University

389

Watershed Transformation Based Identification of the Combustion Region in an Oxy-coal Flame Image  

Science Conference Proceedings (OSTI)

To meet the increasingly stringent standards on pollutant emissions, oxy-coal combustion technologies are being proposed for both existing and new coal-fired power plants. However, there is lack of research to characterize this new type of combustion ... Keywords: edge detection, image enhancement, wavelet transformation, oxy-coal flame, watershed transformation, image segmentation

Tian Qiu; Yong Yan; Gang Lu

2011-08-01T23:59:59.000Z

390

Tabulation of complex chemistry based on self-similar behavior of laminar premixed flames  

SciTech Connect

Detailed mechanisms describing complex phenomena of combustion chemistry, such as flame propagation or pollutant formation, involve hundreds of species and thousands of elementary reactions and cannot be handled in practical simulations of turbulent combustion. A widely used way to reduce chemistry is to build look-up tables where chemical parameters such as reaction rates and/or species mass fractions are determined from a reduced set of coordinates (ILDM, FPI, or FGM methods). Nevertheless, these tables may require large memory spaces and nonnegligible access times, especially when running on massively parallel computers. In this work, the self-similarity behavior of laminar premixed flames is first put into evidence and then theoretically sustained. This property provides a way to reduce the size of chemical databases, especially for computations on massively parallel machines, under the FPI (flame prolongation of ILDM) framework. The database is reduced to similarity profiles for the species reaction rates (or the species mass fractions), stored together with scaling rules. This new formulation is then implemented in the PREMIX code and numerical simulations of laminar premixed flames successfully compare with full chemistry computation, validating this promising approach. (author)

Ribert, G.; Gicquel, O.; Darabiha, N.; Veynante, D. [Laboratoire EM2C, CNRS and Ecole Centrale Paris, 92295 Chatenay-Malabry (France)

2006-09-15T23:59:59.000Z

391

Velocity Fields of Axisymmetric Hydrogen-Air Counterflow Diffusion Flames From LDV, PIV, and Numerical Computation  

Science Conference Proceedings (OSTI)

Laminar fuel-air counterflow diffusion flames (CFDFs) were studied using axisymmetric convergent-nozzle and straight-tube opposed jet burners (OJBs). The subject diagnostics were used to probe a systematic set of H2/N2-air CFDFs over wide ranges of fuel ...

Pellett Gerald L.; Wilson Lloyd G.; Jr William M. Humphreys; Bartram Scott M.; Gartrell Luther R.; Isaac K. M.

1995-07-01T23:59:59.000Z

392

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

E-Print Network (OSTI)

Cellular burning in lean premixed turbulent hydrogen-air flames: coupling experimental for burning the fuel-lean mixtures of hydrogen or hydrogen-rich syngas fuels obtained from the gasification, including those burning lean hydrogen at both at atmospheric and elevated pressures [6]. The low

Bell, John B.

393

Mass burning rate of premixed stretched flames: integral analysis versus large activation energy asymptotics  

E-Print Network (OSTI)

Mass burning rate of premixed stretched flames: integral analysis versus large activation energy, The Netherlands Abstract. New expressions for the mass burning rate are derived from a recently introduced burning rate. The consequences for experimental and numerical studies are investigated. Keywords: premixed

Eindhoven, Technische Universiteit

394

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

395

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

E-Print Network (OSTI)

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

Seitzman, Jerry M.

396

Self-similar solutions of the G-equation - analytic description of the flame surface  

E-Print Network (OSTI)

The main feature of the flame kinematics can be desribed with the G-equation. We investigate the solutions of the G-equation with the well-known self-similar Ansatz. The results are discussed and the method how to get self-similar solutions is briefly mentioned.

I. F. Barna

2010-10-27T23:59:59.000Z

397

Determination of Autoignition and Flame Speed Characteristics of Coal Gases Having Medium Heating Values  

Science Conference Proceedings (OSTI)

Combustion of clean, medium-Btu coal-derived gas offers a way of generating electric power from domestic coal without the sulfur oxide emissions of direct coal combustion. This initial testing yielded data on the spontaneous ignition and turbulent flame speed behavior of such gases that will be valuable for the development of low-NOx combustion systems.

1985-11-11T23:59:59.000Z

398

Flame-driven deflagration-to-detonation transitions in Type Ia supernovae?  

E-Print Network (OSTI)

Although delayed detonation models of thermonuclear explosions of white dwarfs seem promising for reproducing Type Ia supernovae, the transition of the flame propagation mode from subsonic deflagration to supersonic detonation remains hypothetical. A potential instant for this transition to occur is the onset of the distributed burning regime, i.e. the moment when turbulence first affects the internal flame structure. Some studies of the burning microphysics indicate that a deflagration-to-detonation transition may be possible here, provided the turbulent intensities are strong enough. Consequently, the magnitude of turbulent velocity fluctuations generated by the deflagration flame is analyzed at the onset of the distributed burning regime in several three-dimensional simulations of deflagrations in thermonuclear supernovae. It is shown that the corresponding probability density functions fall off towards high turbulent velocity fluctuations much more slowly than a Gaussian distribution. Thus, values claimed to be necessary for triggering a detonation are likely to be found in sufficiently large patches of the flame. Although the microphysical evolution of the burning is not followed and a successful deflagration-to-detonation transition cannot be guaranteed from simulations presented here, the results still indicate that such events may be possible in Type Ia supernova explosions.

F. K. Roepke

2007-09-26T23:59:59.000Z

399

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

DOE Green Energy (OSTI)

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

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

2008-07-01T23:59:59.000Z

400

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

SciTech Connect

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

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

2010-12-15T23:59:59.000Z

Note: This page contains sample records for the topic "flame retention head" 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

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

DOE Green Energy (OSTI)

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

Pickett, L; Siebers, D

2003-08-24T23:59:59.000Z

402

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

SciTech Connect

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

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

2010-12-15T23:59:59.000Z

403

Definition: Head-End System | Open Energy Information  

Open Energy Info (EERE)

Head-End System Head-End System Jump to: navigation, search Dictionary.png Head-End System A head-end system is hardware and software that receives the stream of meter data brought back to the utility through the AMI. Head-end systems may perform a limited amount of data validation before either making the data available for other systems to request or pushing the data out to other systems.[1] Related Terms advanced metering infrastructure, system References ↑ https://www.smartgrid.gov/category/technology/head_end_system [[Ca LikeLike UnlikeLike You and one other like this.One person likes this. Sign Up to see what your friends like. tegory: Smart Grid Definitionssmart grid,smart grid, |Template:BASEPAGENAME]]smart grid,smart grid, Retrieved from "http://en.openei.org/w/index.php?title=Definition:Head-End_System&oldid=502621"

404

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

E-Print Network (OSTI)

High-pressure experiments and chemical kinetics modeling were performed for laminar spherically expanding flames for methane/air, ethane/air, methane/ethane/air and propane/air mixtures at pressures between 1 and 10 atm and equivalence ratios ranging from 0.7 to 1.3. All experiments were performed in a new flame speed facility capable of withstanding initial pressures up to 15 atm. The facility consists of a cylindrical pressure vessel rated up to 2200 psi. Vacuums down to 30 mTorr were produced before each experiment, and mixtures were created using the partial pressure method. Ignition was obtained by an automotive coil and a constant current power supply capable of reducing the spark energy close to the minimum ignition energy. Optical cine-photography was provided via a Z-type schlieren set up and a high-speed camera (2000 fps). A full description of the facility is given including a pressure rating and a computational conjugate heat transfer analysis predicting temperature rises at the walls. Additionally, a detailed uncertainty analysis revealed total uncertainty in measured flame speed of approximately +-0.7 cm/s. This study includes first-ever measurements of methane/ethane flame speeds at elevated pressures as well as unique high pressure ethane flame speed measurements. Three chemical kinetic models were used and compared against measured flame velocities. GRI 3.0 performed remarkably well even for high-pressure ethane flames. The C5 mechanism performed acceptably at low pressure conditions and under-predicted the experimental data at elevated pressures. Measured Markstein lengths of atmospheric methane/air flames were compared against values found in the literature. In this study, Markstein lengths increased for methane/air flames from fuel lean to fuel rich. A reverse trend was observed for ethane/air mixtures with the Markstein length decreasing from fuel lean to fuel rich conditions. Flame cellularity was observed for mixtures at elevated pressures. For both methane and ethane, hydrodynamic instabilities dominated at stoichiometric conditions. Flame acceleration was clearly visible and used to determine the onset of cellular instabilities. The onset of flame acceleration for each high-pressure experiment was recorded.

De Vries, Jaap

2009-05-01T23:59:59.000Z

405

Hydrogen Retention and Release Summary from Tank 48H from September 1995 to October 1996  

DOE Green Energy (OSTI)

This report outlines the results of the investigation with emphasis on the measured hydrogen generation rates and a summary of the hydrogen retention and release behavior.

Peterson, R.A.

1998-09-30T23:59:59.000Z

406

Retention of aerosol particles in the human respiratory tract as a function of particle radius  

SciTech Connect

A water--glycerol aerosol of /sup 24/NaCl (approx. 500 mg/m/sup 3/) was inhaled by 7 volunteers to assess retention of monodispersed aerosols in human respiratory tract. Various particle sizes were tested; dispersion method was thought to be effective. Alveolar retention shows two peaks in the 0.3 to 1 ..mu..m range. Maximum alveolar retention is approx. 45%. Total retention decreased linearly with breathing rate, increased linearly with radius from 0.2 to 1.6 ..mu..m.

Wilson, I.B.; LaMer, V.K.

1948-01-01T23:59:59.000Z

407

Nuclear reactor melt-retention structure to mitigate direct containment heating  

DOE Patents (OSTI)

A light water nuclear reactor melt-retention structure to mitigate the extent of direct containment heating of the reactor containment building. The structure includes a retention chamber for retaining molten core material away from the upper regions of the reactor containment building when a severe accident causes the bottom of the pressure vessel of the reactor to fail and discharge such molten material under high pressure through the reactor cavity into the retention chamber. In combination with the melt-retention chamber there is provided a passageway that includes molten core droplet deflector vanes and has gas vent means in its upper surface, which means are operable to deflect molten core droplets into the retention chamber while allowing high pressure steam and gases to be vented into the upper regions of the containment building. A plurality of platforms are mounted within the passageway and the melt-retention structure to direct the flow of molten core material and help retain it within the melt-retention chamber. In addition, ribs are mounted at spaced positions on the floor of the melt-retention chamber, and grid means are positioned at the entrance side of the retention chamber. The grid means develop gas back pressure that helps separate the molten core droplets from discharged high pressure steam and gases, thereby forcing the steam and gases to vent into the upper regions of the reactor containment building.

Tutu, Narinder K. (Manorville, NY); Ginsberg, Theodore (East Setauket, NY); Klages, John R. (Mattituck, NY)

1991-01-01T23:59:59.000Z

408

Integrated head package for top mounted nuclear instrumentation  

DOE Patents (OSTI)

A nuclear reactor such as a pressurized water reactor has an integrated head package providing structural support and increasing shielding leading toward the vessel head. A reactor vessel head engages the reactor vessel, and a control rod guide mechanism over the vessel head raises and lowers control rods in certain of the thimble tubes, traversing penetrations in the reactor vessel head, and being coupled to the control rods. An instrumentation tube structure includes instrumentation tubes with sensors movable into certain thimble tubes disposed in the fuel assemblies. Couplings for the sensors also traverse penetrations in the reactor vessel head. A shroud is attached over the reactor vessel head and encloses the control rod guide mechanism and at least a portion of the instrumentation tubes when retracted. The shroud forms a structural element of sufficient strength to support the vessel head, the control rod guide mechanism and the instrumentation tube structure, and includes radiation shielding material for limiting passage of radiation from retracted instrumentation tubes. The shroud is thicker at the bottom adjacent the vessel head, where the more irradiated lower ends of retracted sensors reside. The vessel head, shroud and contents thus can be removed from the reactor as a unit and rested safely and securely on a support.

Malandra, Louis J. (McKeesport, PA); Hornak, Leonard P. (Forest Hills, PA); Meuschke, Robert E. (Monroeville, PA)

1993-01-01T23:59:59.000Z

409

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

E-Print Network (OSTI)

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

Grcar, Joseph F

2008-01-01T23:59:59.000Z

410

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

E-Print Network (OSTI)

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

Cheng, Wai K.

411

Molecular shape and the prediction of high-performance liquid chromatographic retention indexes of polycyclic aromatic hydrocarbons  

SciTech Connect

The effects of molecular shape on the retention behavior of polycyclic aromatic hydrocarbons (PAH) have been studied. It has been found that the retention on polymeric phases is highly shape dependent in contrast to the monomeric phases where retention is more dependent on the electronic properties of the solute. In addition, retention on the polymeric phases has been studied with respect to substitution and shape. The retention of substituted PAHs shows a strong dependence on shape, whereas the retention of unsubstituted PAHs is more dependent on electronic properties.

Rohrbaugh, R.H.; Jurs, P.C.

1987-04-01T23:59:59.000Z

412

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

E-Print Network (OSTI)

A burner was designed and constructed to combine weed control practices of parallel and cross-flaming with the technology of covers and insulation. It involved two covers designed to be placed on the sides of a crop row. The flame under the covers was directed parallel to the crop row. Using uniquely designed vanes to divert heated air, the apparatus was designed to re-circulate a portion of heat emitted from the burners for increased fuel efficiency. The apparatus was evaluated by comparing it with the two open flame practices. This evaluation was performed by moving the burners over an area that would monitor the temperatures at specified heights and locations. Temperatures were measured using thermocouples placed at heights 7-mm, 150-mm, and 300-mm in the crop row and height 7-mm in the left and right furrows. Burners traveled at a designated speed (2, 3.5, or 5 km/h) and burner operating pressure combination (207, 276, or 345 kPa). Time versus temperature curves were generated with the data for the temperatures observed. The areas under the curve, above 100 degrees C and within an exposure time boundary were used to compute utilization factors. The utilization factors provided a relative comparison of burner efficiency and performance. At 300-mm in the row, temperatures never exceeded 100 degrees C. At 150-mm in the row, temperatures rarely exceeded 100 degrees C. Sometimes temperatures exceeded 100 degrees C for a brief time. These results were evidence the covered burner re-circulated some heat and excessive amounts of heat were not escaping into the crop canopy. The thermocouples at height 7-mm provided a good indication of temperature activity with the burners. With areas under the curve in the row at 7-mm, open cross-flaming showed higher temperatures for than the covered burner. However, the covered burner had higher utilization factors than open cross-flaming. The covered burner utilization factors were greater than open cross or parallel-flaming in the furrows.

Stark, Christopher Charles

2003-01-01T23:59:59.000Z

413

RETENTION OF SULFATE IN HIGH LEVEL RADIOACTIVE WASTE GLASS  

SciTech Connect

High level radioactive wastes are being vitrified at the Savannah River Site for long term disposal. Many of the wastes contain sulfate at concentrations that can be difficult to retain in borosilicate glass. This study involves efforts to optimize the composition of a glass frit for combination with the waste to improve sulfate retention while meeting other process and product performance constraints. The fabrication and characterization of several series of simulated waste glasses are described. The experiments are detailed chronologically, to provide insight into part of the engineering studies used in developing frit compositions for an operating high level waste vitrification facility. The results lead to the recommendation of a specific frit composition and a concentration limit for sulfate in the glass for the next batch of sludge to be processed at Savannah River.

Fox, K.

2010-09-07T23:59:59.000Z

414

Assessment of gas accumulation and retention -- Tank 241-SY-101  

DOE Green Energy (OSTI)

An approximate analysis has been carried out to assess and estimate the maximum quantity of gas that is likely to be accumulated within waste tank 241-SY-101, and the maximum quantity which is likely to be retained after gas release events (GRE). According to the phenomenological models used for this assessment, based on interpretation of current and recent operational data, the estimated gas generation rate in the tank is approximately 4 m{sup 3}/day (147 ft{sup 3}/day). About half of this gas is released as it is generated, which is (essentially) continuously. The remainder is accumulated within the slurry layer of settled solids at the bottom of the tank, and released episodically in GREs, known as ``burps,`` that are induced by unstable buoyant conditions which develop when sufficient gas accumulates in the slurry. Calculations based on gas volumes to cause neutral buoyancy in the slurry predict the following: the maximum gas accumulation (at 1 atm pressure) that can occur without triggering a GRE is in the range of 606 to 1,039 m{sup 3} (21,400 to 36,700 ft{sup 3}); and the maximum gas retention immediately after a GRE is equal to the maximum accumulation minus the gas released in the GRE. GREs do not necessarily involve all of the slurry. In the largest GREs, which are assumed to involve all of the slurry, the minimum gas release (at 1 atm pressure) is calculated to be in the range of 193 to 328 m{sup 3} (6,800 to 11,600 ft{sup 3}). The corresponding maximum gas retention would be 413 to 711 m{sup 3} (14,600 to 25,100 ft{sup 3}).

Alleman, R.T. [Pacific Northwest Lab., Richland, WA (US); Burke, T.M.; Reynolds, D.A.; Simpson, D.E. [Westinghouse Hanford Co., Richland, WA (US)

1993-03-01T23:59:59.000Z

415

Effects of buoyancy on lean premixed v-flames, Part II. VelocityStatistics in Normal and Microgravity  

SciTech Connect

The field effects of buoyancy on laminar and turbulent premixed v-flames have been studied by the use of laser Doppler velocimetry to measure the velocity statistics in +1g, -1g and {micro}g flames. The experimental conditions covered mean velocity, Uo, of 0.4 to 2 m/s, methane/air equivalence ratio, f, of 0.62 to 0.75. The Reynolds numbers, from 625 to 3130 and the Richardson number from 0.05 to 1.34. The results show that a change from favorable (+1g) to unfavorable (-1g) mean pressure gradient in the plume create stagnating flows in the far field whose influences on the mean and fluctuating velocities persist in the near field even at the highest Re we have investigated. The use of Richardson number < 0.1 as a criterion for momentum dominance is not sufficient to prescribe an upper limit for these buoyancy effects. In {micro}g, the flows within the plumes are non-accelerating and parallel. Therefore, velocity gradients and hence mean strain rates in the plumes of laboratory flames are direct consequences of buoyancy. Furthermore, the rms fluctuations in the plumes of {micro}g flames are lower and more isotropic than in the laboratory flames to show that the unstable plumes in laboratory flames also induce velocity fluctuations. The phenomena influenced by buoyancy i.e. degree of flame wrinkling, flow acceleration, flow distribution, and turbulence production, can be subtle due to their close coupling with other flame flow interaction processes. But they cannot be ignored in fundamental studies or else the conclusions and insights would be ambiguous and not very meaningful.

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

1999-07-01T23:59:59.000Z

416

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

Science Conference Proceedings (OSTI)

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

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

2011-01-15T23:59:59.000Z

417

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

E-Print Network (OSTI)

Numerous studies have focused on enhancing the flame retardant behavior of cotton and polyurethane foam. Some of the most commonly used treatments (e.g., brominated compounds) have raised concerns with regard to toxicity and environmental persistence. These concerns have led to significant research into the use of alternative approaches, including polymer nanocomposites prepared from more environmentally benign nanoparticles. These particles migrate to the surface from the bulk during fire exposure to form a barrier on the surface that protects the underlying polymer. This theory of fire suppression in bulk nanocomposites inspired the use of layer-by-layer (LbL) assembly to create nanocoatings in an effort to produce more effective and environmentally-benign flame retardant treatments. Negatively charged silica nanoparticles of two different sizes were paired with either positively charged silica or cationic polyethylenimine (PEI) to create thin film assemblies. When applying these films to cotton fabric, all coated fabrics retained their weave structure after being exposed to a vertical flame test, while uncoated cotton was completely destroyed. Micro combustion calorimetry confirmed that coated fabrics exhibited a reduced peak heat release rate, by as much as 20% relative to the uncoated control. Even so, this treatment would not pass the standard UL94 vertical flame test, necessitating a more effective treatment. Positively- charged chitosan (CH) was paired with montmorillonite (MMT) clay to create a renewable flame retardant nanocoating for polyurethane foam. This coating system completely stops the melting of a flexible polyurethane foam when exposed to direct flame from a butane torch, with just 10 bilayers (~ 30 nm thick). The same coated foam exhibited a reduced peak heat release rate, by as much as 52%, relative to the uncoated control. This same nanobrick wall coating is able to impart gas barrier to permeate plastic film. Multilayered thin films were assembled with "green" food contact approved materials (i.e., chitosan, polyacrylic acid (PAA) and montmorillonite clay). Only ten CH-PAA-CH-MMT quadlayers (~90 nm thick) cause polylactic acid (PLA) film to behave like PET in terms of oxygen barrier. A thirty bilayer CH-MMT assembly (~100 nm thick) on PLA exhibits an oxygen transmission rate (OTR) below the detection limit of commercial instrumentation (<= 0.005 cm^3/(m^2*day*atm)). This is the same recipe used to impart flame retardant behavior to foam, but it did not provide effective FR to cotton fabric, so a very different recipe was used. Thin films of fully renewable electrolytes, chitosan and phytic acid (PA), were deposited on cotton fabric in an effort to reduce flammability through an intumescent effect. Altering the pH of aqueous deposition solutions modifies the composition of the final nanocoating. Fabrics coated with highest PA content multilayers completely extinguished the flame and reduced peak heat release (pkHRR) and total heat release of 60% and 76%, respectively. This superior performance is believed to be due to high phosphorus content that enhances the intumescent behavior of these nanocoatings.

Laufer, Galina 1985-

2012-12-01T23:59:59.000Z

418

A joint computational and experimental study to evaluate Inconel-sheathed thermocouple performance in flames.  

Science Conference Proceedings (OSTI)

A joint experimental and computational study was performed to evaluate the capability of the Sandia Fire Code VULCAN to predict thermocouple response temperature. Thermocouple temperatures recorded by an Inconel-sheathed thermocouple inserted into a near-adiabatic flat flame were predicted by companion VULCAN simulations. The predicted thermocouple temperatures were within 6% of the measured values, with the error primarily attributable to uncertainty in Inconel 600 emissivity and axial conduction losses along the length of the thermocouple assembly. Hence, it is recommended that future thermocouple models (for Inconel-sheathed designs) include a correction for axial conduction. Given the remarkable agreement between experiment and simulation, it is recommended that the analysis be repeated for thermocouples in flames with pollutants such as soot.

Brundage, Aaron L.; Nicolette, Vernon F.; Donaldson, A. Burl; Kearney, Sean Patrick; Gill, Walter

2005-09-01T23:59:59.000Z

419

Direct numerical simulation of temporally evolving luminous jet flames with detailed fuel and soot chemistry  

Science Conference Proceedings (OSTI)

Direct numerical simulations of 2D temporally-evolving luminous turbulent ethylene-air jet diffusion flames are performed using a high-order compressible Navier-Stokes solver. The simulations use a reduced mechanism derived from a detailed ethylene-air chemical kinetic mechanism that includes the reaction pathways for the formation of polycyclic aromatic hydrocarbons. The gas-phase chemistry is coupled with a detailed soot particle model based on the method of moments with interpolative closure that accounts for soot nucleation, coagulation, surface growth through HACA mechanism, and oxidation. Radiative heat transfer of CO{sub 2}, H{sub 2}O, and soot is treated by solving the radiative transfer equation using the discrete transfer method. This work presents preliminary results of radiation effects on soot dynamics at the tip of a jet diffusion flame with a particular focus on soot formation/oxidation.

Sankaran, Ramanan [ORNL

2011-01-01T23:59:59.000Z

420

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

E-Print Network (OSTI)

Three pulsed narrow band pump sources (a frequency doubled pulsed Nd-YAG, and two narrow band dye lasers) and a broad-band Stokes laser source are used to demonstrate triple pump coherent anti-Stokes Raman scattering in a jet diffusion flame. This new diagnostic technique is used to probe for three flame species simultaneously with a single laser pulse. Both temperature and species concentration can be determined with a single laser pulse because of simultaneous excitation of many Raman lines with a broad-band Stokes beam source. The spectra are recorded using a 1-m spectrometer and a back-illuminated unintensified CCD camera. The temperature and species concentration (H?/N? and O?/N?) ratios are obtained with high temporal and spatial resolution.

Velur Natarajan, Viswanathan

2002-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "flame retention head" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
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421

Gas bubble retention and its effect on waste properties: Retention mechanisms, viscosity, and tensile and shear strengths  

SciTech Connect

Several of the underground nuclear storage tanks at Hanford have been placed on a flammable gas watch list, because the waste is either known or suspected to generate, store, and episodically release flammable gases. Because retention and episodic release of flammable gases from these tanks containing radioactive waste slurries are critical safety concerns, Pacific Northwest Laboratory (PNL) is studying physical mechanisms and waste properties that contribute to the episodic gas release from these storage tanks. This study is being conducted for Westinghouse Hanford Company as part of the PNL Flammable Gas project. Previous investigations have concluded that gas bubbles are retained by the slurry or sludge that has settled at the bottom of the tanks; however, the mechanisms responsible for the retention of these bubbles are not well understood. Understanding the rheological behavior of the waste, particularly of the settled sludge, is critical to characterizing the tendency of the waste to retain gas bubbles and the dynamics of how these bubbles are released from the waste. The presence of gas bubbles is expected to affect the rheology of the sludge, specifically its viscosity and tensile and shear strengths, but essentially no literature data are available to assess the effect of bubbles. The objectives of this study were to conduct experiments and develop theories to understand better how bubbles are retained by slurries and sludges, to measure the effect of gas bubbles on the viscosity of simulated slurries, and to measure the effect of gas bubbles on the tensile and shear strengths of simulated slurries and sludges. In addition to accomplishing these objectives, this study developed correlations, based on the new experimental data, that can be used in large-scale computations of waste tank physical phenomena.

Gauglitz, P.A.; Rassat, S.D.; Powell, M.R. [and others

1995-08-01T23:59:59.000Z

422

Heading Error Removal System for Tracking Devices - Energy ...  

Systems are able to reduce or remove slowly-varying drift errors, such as heading errors, rate of rotation errors, and direction of travel errors, to correct the ...

423

Memorandum to Heads of Federal Departments and Agencies Regarding Pollution  

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

Memorandum to Heads of Federal Departments and Agencies Regarding Memorandum to Heads of Federal Departments and Agencies Regarding Pollution Prevention and the National Environmental Policy Act Memorandum to Heads of Federal Departments and Agencies Regarding Pollution Prevention and the National Environmental Policy Act This memorandum provides guidance to the federal agencies on incorporating pollution prevention principles, techniques, and mechanisms into their planning and decisionmaking processes and evaluating and reporting those efforts in documents prepared pursuant to the National Environmental Policy Act. Memorandum to Heads of Federal Departments and Agencies Regarding Pollution Prevention and the National Environmental Policy Act More Documents & Publications Integrating Pollution Prevention with NEPA Planning Activities

424

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

DOE Green Energy (OSTI)

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

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

1996-07-01T23:59:59.000Z

425

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

426

Low and High Temperature Combustion Chemistry of Butanol Isomers in Premixed Flames and Autoignition Systems  

Science Conference Proceedings (OSTI)

Butanol is a fuel that has been proposed as a bio-derived alternative to conventional petroleum derived fuels. The structural isomer in traditional 'bio-butanol' fuel is n-butanol, but newer conversion technologies produce iso-butanol as a fuel. In order to better understand the combustion chemistry of bio-butanol, this study presents a comprehensive chemical kinetic model for all the four isomers of butanol (e.g., 1-, 2-, iso- and tert-butanol). The proposed model includes detailed high temperature and low temperature reaction pathways. In this study, the primary experimental validation target for the model is premixed flat low-pressure flame species profiles obtained using molecular beam mass spectrometry (MBMS). The model is also validated against previously published data for premixed flame velocity and n-butanol rapid compression machine and shock tube ignition delay. The agreement with these data sets is reasonably good. The dominant reaction pathways at the various pressures and temperatures studied are elucidated. At low temperature conditions, we found that the reaction of alphahydroxybutyl with O{sub 2} was important in controlling the reactivity of the system, and for correctly predicting C{sub 4} aldehyde profiles in low pressure premixed flames. Enol-keto isomerization reactions assisted by HO{sub 2} were also found to be important in converting enols to aldehydes and ketones in the low pressure premixed flames. In the paper, we describe how the structural features of the four different butanol isomers lead to differences in the combustion properties of each isomer.

Sarathy, S M; Pitz, W J; Westbrook, C K; Mehl, M; Yasunaga, K; Curran, H J; Tsujimura, T; Osswald, P; Kohse-Hoinghaus, K

2010-12-12T23:59:59.000Z

427

Scaling of cell size in cellular instabilities of nonpremixed jet flames  

SciTech Connect

Systematic experiments have been undertaken to study the parameter dependence of cellular instability and in particular the scaling of the resulting cell size in CO{sub 2}-diluted H{sub 2}-O{sub 2} jet diffusion flames. Cellular flames are known to arise near the extinction limit when reactant Lewis numbers are relatively low. The Lewis numbers of the investigated near-extinction mixtures, based on the initial mixture strength {phi}{sub m} and ambient conditions, varied in the ranges [1.1-1.3] for oxygen and [0.25-0.29] for hydrogen ({phi}{sub m} is defined here as the fuel-to-oxygen mass ratio, normalized by the stoichiometric ratio). The experiments were carried out both in an axisymmetric jet (AJ) burner and in a two-dimensional slot burner known as a Wolfhard-Parker (WP) burner with an oxidizer co-flow (mostly 100% O{sub 2}) of fixed low velocity. First, the region of cellular flames adjacent to the extinction limit was characterized in terms of initial H{sub 2} concentration and fuel jet velocity, with all other parameters fixed. Then, the wavelength of the cellular instability, i.e., the cell size, was determined as a function of the fuel jet velocity and the initial mixture strength {phi}{sub m}. For conditions not too close to extinction, this wavelength is found to increase with the square root of the vorticity thickness of the jet shear layer and roughly the 1/5 power of {phi}{sub m}. Very close to extinction, this scaling breaks down and will likely switch to a scaling with the flame thickness, i.e., involving the Damkoehler number. (author)

Lo Jacono, D.; Monkewitz, P.A. [Ecole Polytechnique Federale de Lausanne, Laboratory of Fluid Mechanics, CH-1015 Lausanne (Switzerland)

2007-10-15T23:59:59.000Z

428

The Flame Doctor (TM) Burner Monitoring System: Demonstration Tests at AmerenUE's Meramec Unit 4  

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. Global emissions monitoring is certainly important for boiler control, but 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 and ...

2002-11-13T23:59:59.000Z

429

VLT-FLAMES observations of young stellar clusters in the Magellanic Clouds  

E-Print Network (OSTI)

We introduce our VLT-FLAMES survey of massive stars in the Galaxy and the Magellanic Clouds, giving details of the observations in our younger fields in the LMC and SMC. In particular we highlight a new O2.5-type star discovered in N11, and Be-type stars in NGC 346 with permitted Fe II emission lines in their spectra. We give an overview of the distribution of spectral types in these fields and summarize the observed binary fraction.

C. J. Evans; D. J. Lennon; S. J. Smartt

2005-08-30T23:59:59.000Z

430

Integral field spectroscopy of protoplanetary disks in Orion with VLT FLAMES  

E-Print Network (OSTI)

We discuss integral field spectroscopy of proplyds in M42 using the FLAMES Argus unit and report the first detection of recombination lines of C II and O II from the archetypical Laques-Vidal-2 object. These lines can provide important new diagnostics of the physical conditions in proplyds. We also draw attention to the future capabilities of the MUSE spectrograph in relation to similar studies.

Y. G. Tsamis; J. R. Walsh; D. Péquignot

2008-04-07T23:59:59.000Z

431

Quenching-independent measurement of species concentrations in flames by laser-induced fluorescence  

DOE Green Energy (OSTI)

This report describes work accomplished in the last two years on measurement of species concentrations in flames via laser-induced fluorescence. During this period, we have published absolute number densities of atomic hydrogen in subatmospheric, premixed C{sub 2}H{sub 4}/O{sub 2}/Ar flames at equivalence ratios of 1.0 and 1.7 via two-photon excited fluorescence. This work has led to the development of a new single-laser, two-step fluorescence method for the detection of atomic hydrogen in flames. Using photoionization controlled-loss spectroscopy (PICLS), we have verified the T{sup {minus}1/2} dependence of quenching on temperature for atomic hydrogen, in agreement with kinetic theory. Previous work on pyrometry using laser-saturated fluorescence (LSF) and the anomalous fluorescence from pyrene has evolved into publication of a major review paper on temperature measurements by light-scattering methods. Finally, we have demonstrated the feasibility of quantitative LSF measurements of NO concentration by obtaining relative saturation curves and NO fluorescence profiles. 25 refs.

Salmon, J.T.; Carter, C.D.; Laurendeau, N.M.

1990-09-01T23:59:59.000Z

432

Direct numerical simulations of type Ia supernovae flames II: The Rayleigh-Taylor instability  

Science Conference Proceedings (OSTI)

A Type Ia supernova explosion likely begins as a nuclear runaway near the center of a carbon-oxygen white dwarf. The outward propagating flame is unstable to the Landau-Darrieus, Rayleigh-Taylor, and Kelvin-Helmholtz instabilities, which serve to accelerate it to a large fraction of the speed of sound. We investigate the Rayleigh-Taylor unstable flame at the transition from the flamelet regime to the distributed-burning regime, around densities of 10e7 gm/cc, through detailed, fully resolved simulations. A low Mach number, adaptive mesh hydrodynamics code is used to achieve the necessary resolution and long time scales. As the density is varied, we see a fundamental change in the character of the burning--at the low end of the density range the Rayleigh-Taylor instability dominates the burning, whereas at the high end the burning suppresses the instability. In all cases, significant acceleration of the flame is observed, limited only by the size of the domain we are able to study. We discuss the implications of these results on the potential for a deflagration to detonation transition.

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

2004-01-12T23:59:59.000Z

433

TYPE Ia SUPERNOVAE: CALCULATIONS OF TURBULENT FLAMES USING THE LINEAR EDDY MODEL  

SciTech Connect

The nature of carbon burning flames in Type Ia supernovae is explored as they interact with Kolmogorov turbulence. One-dimensional calculations using the Linear Eddy Model of Kerstein elucidate three regimes of turbulent burning. In the simplest case, large-scale turbulence folds and deforms thin laminar flamelets to produce a flame brush with a total burning rate given approximately by the speed of turbulent fluctuations on the integral scale, U{sub L} , This is the regime where the supernova explosion begins and where most of its pre-detonation burning occurs. As the density declines, turbulence starts to tear the individual flamelets, making broader structures that move faster. For a brief time, these turbulent flamelets are still narrow compared to their spacing and the concept of a flame brush moving with an overall speed of U{sub L} remains valid. However, the typical width of the individual flamelets, which is given by the condition that their turnover time equals their burning time, continues to increase as the density declines. Eventually, mixed regions almost as large as the integral scale itself are transiently formed. At that point, a transition to detonation can occur. The conditions for such a transition are explored numerically and it is estimated that the transition will occur for densities near 1 x 10{sup 7} g cm{sup -3}, provided the turbulent speed on the integral scale exceeds about 20% sonic. An example calculation shows the details of a detonation actually developing.

Woosley, S. E. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Kerstein, A. R.; Sankaran, V. [Combustion Research Facility, Sandia National Laboratory, Livermore, CA 94551 (United States); Aspden, A. J. [Center for Computational Science and Engineering, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Roepke, F. K., E-mail: woosley@ucolick.or, E-mail: arkerst@sandia.go, E-mail: AJAspden@lbl.go, E-mail: fritz@mpa-Garching.mpg.d [Max Planck Institut fuer Astrophysik, Garching (Germany)

2009-10-10T23:59:59.000Z

434

Flame Evolution During Type Ia Supernovae and the Deflagration Phase in the Gravitationally Confined Detonation Scenario  

E-Print Network (OSTI)

We develop an improved method for tracking the nuclear flame during the deflagration phase of a Type Ia supernova, and apply it to study the variation in outcomes expected from the gravitationally confined detonation (GCD) paradigm. A simplified 3-stage burning model and a non-static ash state are integrated with an artificially thickened advection-diffusion-reaction (ADR) flame front in order to provide an accurate but highly efficient representation of the energy release and electron capture in and after the unresolvable flame. We demonstrate that both our ADR and energy release methods do not generate significant acoustic noise, as has been a problem with previous ADR-based schemes. We proceed to model aspects of the deflagration, particularly the role of buoyancy of the hot ash, and find that our methods are reasonably well-behaved with respect to numerical resolution. We show that if a detonation occurs in material swept up by the material ejected by the first rising bubble but gravitationally confined to the white dwarf (WD) surface (the GCD paradigm), the density structure of the WD at detonation is systematically correlated with the distance of the deflagration ignition point from the center of the star. Coupled to a suitably stochastic ignition process, this correlation may provide a plausible explanation for the variety of nickel masses seen in Type Ia Supernovae.

D. M. Townsley; A. C. Calder; S. M. Asida; I. R. Seitenzahl; F. Peng; N. Vladimirova; D. Q. Lamb; J. W. Truran

2007-06-07T23:59:59.000Z

435

Mars mission laser tool heads to JPL  

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

Mars mission laser tool Mars mission laser tool Mars mission laser tool heads to JPL Curiosity will carry the newly delivered laser instrument to reveal which elements are present in Mars' rocks and soils. September 21, 2010 A bright ball of plasma is produced by ChemCam's invisible laser beam striking a rock within the Mars sample chamber. A bright ball of plasma is produced by ChemCam's invisible laser beam striking a rock within the Mars sample chamber. Contact Nancy Ambrosiano Communications Office (505) 667-0471 Email "ChemCam will act as a geochemical observatory, providing composition data to understand if Mars was, is, or will be a habitable world." Star Wars photon gun will give Mars rover hands-free rock ID LOS ALAMOS, New Mexico, September 21, 2010-The ChemCam instrument has

436

Closure head for a nuclear reactor  

DOE Patents (OSTI)

A closure head for a nuclear reactor includes a stationary outer ring integral with the reactor vessel with a first rotatable plug disposed within the stationary outer ring and supported from the stationary outer ring by a bearing assembly. A sealing system is associated with the bearing assembly to seal the annulus defined between the first rotatable plug and the stationary outer ring. The sealing system comprises tubular seal elements disposed in the annulus with load springs contacting the tubular seal elements so as to force the tubular seal elements against the annulus in a manner to seal the annulus. The sealing system also comprises a sealing fluid which is pumped through the annulus and over the tubular seal elements causing the load springs to compress thereby reducing the friction between the tubular seal elements and the rotatable components while maintaining a gas-tight seal therebetween.

Wade, Elman E. (South Huntingdon, PA)

1980-01-01T23:59:59.000Z

437

Light water reactor lower head failure analysis  

SciTech Connect

This document presents the results from a US Nuclear Regulatory Commission-sponsored research program to investigate the mode and timing of vessel lower head failure. Major objectives of the analysis were to identify plausible failure mechanisms and to develop a method for determining which failure mode would occur first in different light water reactor designs and accident conditions. Failure mechanisms, such as tube ejection, tube rupture, global vessel failure, and localized vessel creep rupture, were studied. Newly developed models and existing models were applied to predict which failure mechanism would occur first in various severe accident scenarios. So that a broader range of conditions could be considered simultaneously, calculations relied heavily on models with closed-form or simplified numerical solution techniques. Finite element techniques-were employed for analytical model verification and examining more detailed phenomena. High-temperature creep and tensile data were obtained for predicting vessel and penetration structural response.

Rempe, J.L.; Chavez, S.A.; Thinnes, G.L. [EG and G Idaho, Inc., Idaho Falls, ID (United States)] [and others

1993-10-01T23:59:59.000Z

438

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

SciTech Connect

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

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

1998-05-01T23:59:59.000Z

439

Propagation and extinction of premixed C{sub 5}-C{sub 12}n-alkane flames  

SciTech Connect

Laminar flame speeds and extinction strain rates of premixed C{sub 5}-C{sub 12}n-alkane flames were determined at atmospheric pressure and elevated unburned mixture temperatures, over a wide range of equivalence ratios. Experiments were performed in the counterflow configuration and flow velocities were measured using Laser Doppler Velocimetry. The laminar flame speeds were obtained using a non-linear extrapolation technique utilizing numerical simulations of the counterflow experiments with detailed descriptions of chemical kinetics and molecular transport. Compared to linearly extrapolated values, the laminar flame speeds obtained using non-linear extrapolations were found to be 1-4 cm/s lower depending on the equivalence ratio. It was determined that the laminar flame speeds of all n-alkane/air mixtures considered in this investigation are similar to each other and sensitive largely to the H{sub 2}/CO and C{sub 1}-C{sub 4} hydrocarbon kinetics. Additionally, the resistance to extinction decreases as the fuel molecular weight increases. Simulations of the experiments were performed using the recently developed JetSurF 0.2 reaction model consisting of 194 species and 1459 reactions. The laminar flame speeds were predicted with good accuracy for all the n-alkane-air mixtures considered. The experimental extinction strain rates are well predicted by the model for fuel-lean mixtures. For stoichiometric and fuel-rich mixtures, the predicted extinction strain rates are approximately 10% lower than the experimental values. Insights into the physical and chemical processes that control the response of n-alkane flames are provided through detailed sensitivity analyses on both reaction rates and binary diffusion coefficients. (author)

Ji, Chunsheng; Dames, Enoch; Wang, Yang L.; Wang, Hai; Egolfopoulos, Fokion N. [Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA 90089-1453 (United States)

2010-02-15T23:59:59.000Z

440

An integrated approach for head gesture based interface  

Science Conference Proceedings (OSTI)

The head pose and movement of a user is closely related with his/her intention and thought, recognition of such information could be useful to develop a natural and sensitive user-wheelchair interface. This paper presents an original integrated approach ... Keywords: Electric powered wheelchair, Face authentication, Facial pose estimation, Head gesture based interface, State machine

Gin Chong Lee; Chu Kiong Loo; Letchumanan Chockalingam

2012-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "flame retention head" 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

A Mathematical Model for a Vibrating Human Head  

Science Conference Proceedings (OSTI)

In this paper, a mathematical model has been formulated to study the vibration of the human head. In the mathematical analysis of the model, the skull is considered as an anisotropic spherical shell and brain matter is represented as an inviscid compressible ... Keywords: Anisotropic, Human Head, Laplace Transformation, Skull Vibration, Stress Distribution

J. C. Misra; S. Dandapat; S. Adhikary

2010-04-01T23:59:59.000Z

442

Distribution of visual attention in head-worn displays  

Science Conference Proceedings (OSTI)

With head-worn displays, information can be presented in addition to the real surround. But, the virtual information is self-illuminating, has an unclear depth, and, depending on the visual background, the signal-noise ratio and the brightness contrast ... Keywords: head-worn displays, optical see-through displays, visual search

Anke Huckauf; Mario H. Urbina; Fabina Doil; Johannes Tümler; Rüdiger Mecke

2008-08-01T23:59:59.000Z

443

A M3G Talking Head for Smartphones  

Science Conference Proceedings (OSTI)

Often customer information services or virtual support guides make use of friendly interface to facilitate human-machine interaction. Indeed, virtual guided tours or helpdesks use a talking anthropomorphic head to communicate with the user. In this paper, ... Keywords: Talking Head, M3G, Smartphones, PDA, J2ME

O. Gambino; A. Caronia; V. Di Bella; R. Pirrone; S. Gaglio

2011-06-01T23:59:59.000Z

444

Assessment of concentrations of trace organic contaminants in sediments at Rame Head Cefas Multi-disciplinary Project Team  

E-Print Network (OSTI)

Concentrations of organic contaminants were determined in seabed sediments from the Rame Head area. These are presented here together with concentrations of the same contaminants determined at other disposal grounds around England and Wales. Brominated flame retardants (BFR) Polychlorinated biphenyls (PCB) The use of PCB has been controlled for over 20 years, but their persistence in the environment means that they are still detectable today. Organochlorine pesticides (OCP) The OCPs studied in this survey were dichlorodiphenyltrichloroethane (p,p’-DDT) and its degradation products/metabolites p,p’-DDE and p,p’-TDE, hexachlorobenzene (HCB), dieldrin and hexachlorocyclohexane (HCH). BFR determined were the brominated diphenyl ethers (BDE) and hexabromocyclododecane (HBCD). Total BDE ? 10 congeners Total PCB ? 25 congeners Elevated concentrations of PCB at the disposal site are probably due to historic disposal activity. Concentrations of PCB at the SAC and outside the disposal area are either low or below the limit of detection of the methods used. Dieldrin Polycyclic aromatic hydrocarbons (PAH) A range of oil and combustion-derived PAH were monitored in this survey. Total DDT ? p,p’-DDT, p,p’-DDE and p,p’-TDE concentrations Total HBCD ? ?, ? and ?-HBCD isomers. Except for p,p’-DDT at one site, all OCP concentrations were low, below sediment quality guidelines 2,3. Concentrations of BFR measured in this study are comparable to the lowest concentrations detected in European marine sediments 1 and at other disposal grounds around the UK. These concentrations of BFR represent general environmental background, which may have resulted from a combination of diffuse inputs and atmospheric deposition. References Environmental impacts resulting from disposal of dredged material at the Rame Head disposal site, S.W.

The Centre For Environment; Aquaculture Science

2005-01-01T23:59:59.000Z

445

Bushing retention system for thermal medium cooling delivery tubes in a gas turbine rotor  

SciTech Connect

Bushings are provided in counterbores for wheels and spacers for supporting thermal medium cooling tubes extending axially adjacent the rim of the gas turbine rotor. The retention system includes a retaining ring disposed in a groove adjacent an end face of the bushing and which retaining ring projects radially inwardly to prevent axial movement of the bushing in one direction. The retention ring has a plurality of circumferentially spaced tabs along its inner diameter whereby the ring is supported by the lands of the tube maintaining its bushing retention function, notwithstanding operation in high centrifugal fields and rotation of the ring in the groove into other circular orientations.

Mashey, Thomas Charles (Coxsackie, NY)

2002-01-01T23:59:59.000Z

446

MFRSR Head Refurbishment, Data Logger Upgrade and Calibration Improvements  

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

MFRSR Head Refurbishment, Data Logger Upgrade MFRSR Head Refurbishment, Data Logger Upgrade and Calibration Improvements Gary Hodges, CIRES/NOAA and John Schmelzer, PNL gary.hodges@noaa.gov, john.schmelzer@pnl.gov 17th Annual ARM Science Team Meeting 26-30 March 2006 Monterey, CA Head Refurbishment The Process Includes: * New filter detectors * Relocate internal thermistors * New connectors * Gain resistors moved to head * Improved insulation The Finished Heads: * Are lamp calibrated * Have filter profiles measured * Cosine characterized * Are out-of-band tested What Does This Mean For Data Users? * Fewer data gaps * Fewer DQRs * Confidence in the data * Well calibrated data Calibration Improvements 5 6 7 8 0 2 4 6 Airmass ln Direct Data will now be calibrated by the Langley method Extrapolate to TOA to get V 0 Benefits of Langley vs. Lamp calibrations:

447

Tracking Santa: An Interview with the Head Researcher | Department of  

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

Tracking Santa: An Interview with the Head Researcher Tracking Santa: An Interview with the Head Researcher Tracking Santa: An Interview with the Head Researcher December 23, 2010 - 11:12am Addthis Tracking Santa: An Interview with the Head Researcher Ginny Simmons Ginny Simmons Former Managing Editor for Energy.gov, Office of Public Affairs What does this mean for me? You'll be able to start monitoring St. Nick's journey starting at 6 AM ET on Christmas Eve. Every year since 1998, the Department of Energy's Los Alamos lab has been using state of the art technology to track Santa Claus as he circles the globe the night before Christmas. You'll be able to start monitoring St. Nick's journey here starting at 6 AM ET on Christmas Eve. This week, I got a chance to talk to Santa Tracker Head Researcher (and Cibola Flight Experiment Project Leader) Diane Roussel-Dupre to get a

448

Reactor Vessel Head Disposal Campaign for Nuclear Management Company  

SciTech Connect

After establishing a goal to replace as many reactor vessel heads as possible - in the shortest time and at the lowest cost as possible - Nuclear Management Company (NMC) initiated an ambitious program to replace the heads on all six of its pressurized water reactors. Currently, four heads have been replaced; and four old heads have been disposed of. In 2002, NMC began fabricating the first of its replacement reactor vessel heads for the Kewaunee Nuclear Plant. During its fall 2004 refueling outage, Kewaunee's head was replaced and the old head was prepared for disposal. Kewaunee's disposal project included: - Down-ending, - Draining, - Decontamination, - Packaging, - Removal from containment, - On-Site handling, - Temporary storage, - Transportation, - Disposal. The next two replacements took place in the spring of 2005. Point Beach Nuclear Plant (PBNP) Unit 2 and Prairie Island Nuclear Generating Plant (PINGP) Unit 2 completed their head replacements during their scheduled refueling outages. Since these two outages were scheduled so close to each other, their removal and disposal posed some unique challenges. In addition, changes to the handling and disposal programs were made as a result of lessons learned from Kewaunee. A fourth head replacement took place during PBNP Unit 1's refueling outage during the fall of 2005. A number of additional changes took place. All of these changes and challenges are discussed in the paper. NMC's future schedule includes PINGP Unit 1's installation in Spring 2006 and Palisades' installation during 2007. NMC plans to dispose of these two remaining heads in a similar manner. This paper presents a summary of these activities, plus a discussion of lessons learned. (authors)

Hoelscher, H.L.; Closs, J.W. [Nuclear Management Company, LLC, 700 First Street, Hudson, WI 54016 (United States); Johnson, S.A. [Duratek, Inc., 140 Stoneridge Drive, Columbia, SC 29210 (United States)

2006-07-01T23:59:59.000Z

449

Influence of a combustion-driven oscillation on global mixing in the flame from a refinery flare  

Science Conference Proceedings (OSTI)

An assessment of the influence of strong combustion-driven oscillations on mixing rates and visible radiation in the flame from a full-scale refinery flare is reported. Importantly, the oscillations were generated naturally, with no external forcing, and at a high Reynolds number of 4 x 10{sup 6}. These conditions differentiate this study from those of previous investigations, which all involved some external forcing and were at a Re too low to ensure fully turbulent flow within the flame. A frame-by-frame analysis of video footage, providing good resolution of the instantaneous edge of each flame, was used to assess flame dimensions, and so to determine a global residence time. Since the flames are in the fast-chemistry regime, the visual imagers can be used to determine a global mixing rate. The analysis reveals a consistent picture that the combustion-driven oscillations do not result in a significant change to the global mixing rate, but do increase the visible radiation. This is in contrast to previous investigations, using externally forced jets, where forcing at the preferred mode has been found to increase mixing rates and reduce radiation. (author)

Langman, A.S.; Nathan, G.J. [School of Mechanical Engineering, Centre for Energy Technology, The University of Adelaide, SA 5005 (Australia)

2011-01-15T23:59:59.000Z

450

Mercury retention by fly ashes from coal combustion: Influence of the unburned carbon content  

Science Conference Proceedings (OSTI)

The objective of this study was to evaluate the effect of unburned carbon particles present in fly ashes produced by coal combustion on mercury retention. To achieve this objective, the work was divided into two parts. The aim of the first part of the study was to estimate the amount of mercury captured by the fly ashes during combustion in power stations and the relationship of this retention to the unburned carbon content. The second part was a laboratory-scale study aimed at evaluating the retention of mercury concentrations greater than those produced in power stations by fly ashes of different characteristics and by unburned carbon particles. From the results obtained it can be inferred that the unburned carbon content is not the only variable that controls mercury capture in fly ashes. The textural characteristics of these unburned pa