3 edition of Effects of buoyancy on gas jet diffusion flames found in the catalog.
Effects of buoyancy on gas jet diffusion flames
M. Yousef Bahadori
by National Aeronautics and Space Administration, National Technical Information Service, distributor in [Washington, DC], [Springfield, Va
Written in English
|Statement||M. Yousef Bahadori and Raymond B. Edelman.|
|Series||NASA contractor report -- 191109., NASA contractor report -- NASA CR-191109.|
|Contributions||Edelman, R. B., United States. National Aeronautics and Space Administration.|
|The Physical Object|
destruction (D) and diffusion of flame surface density. The goals of the present work are: to quantify the effects of buoyancy and visualize the relevant physics, and to provide benchmark data that is buoyancy-free which can be used to assess Direct Numerical Simulations of flame-vortex interactions and to improve turbulent combustion models. The effects of gravity on the physical and compositional structures of transitional and turbulent diffusion flames are studied via analysis of the data generated by direct numerical simulation of a planar jet flame at various gravity conditions. A fully compressible, high-order compact, finite-difference computational scheme is used together with a global kinetics model for chemical by: 7.
] lifted jet diffusion flame in co-flow of air have been studied extensively. However, the co-flow air effect on the dynamics of laminar un-lifted diffusion flames is left almost unattended in literatures. The lift-off height in co-flow jets was found to increase highly nonlinearly with fuel jet velocity and was sensitive toFile Size: KB. All four experiments were studies of laminar, axisymmetric, gas-jet diffusion flames. This is true of even the TGDF experiment, where the flame was not turbulent but where an iris mechanism around its base induced vortices in the entrained air. While TGDF and LSP flames were within sealed chambers, ELF and SPICE flames were within fan-driven.
ancy-driven diffusion flames may now be ob- tained by coupling Eqs. 14 and Since velocity is a dependent variable for any buoyancy-driven flow, its elimination between these equations yields -- 1 + -- ~ --, (17) 6m 4 v vD m which, in terms of a flame Schmidt number, P oe De (18). A.K. Agrawal, “Buoyancy Effects on Hydrogen Gas-Jet Diffusion Flames,” Invited Seminar, Oklahoma State University, January A.K. Agrawal, “Hydrogen Gas-Jet Diffusion Flames in Microgravity,” Invited Seminar, Indian Institute of Technology, Kanpur, June
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Efforts to isolate the buoyancy effects in laminar gas-jet diffusion flames have so far been limited to the s NASA-Lewis drop-tower (gravity levels 10 5g) experiments[l ] and accompanying nu- Cited by: Gas jet diffusion flames have been a subject of research for many years.
However, while the effects of gravity on the burning process have been observed, the influences of buoyancy on the physico-chemical processes occurring in these flames have yet to be by: The objective of this effort was to gain a better understanding of the fundamental phenomena involved in laminar gas jet diffusion flames in the absence of.
The effects of oxygen enhancement on ethane fueled laminar gas jet diffusion flames was examined for both earth gravity and microgravity in both normal and inverse flames.
Get this from a library. Effects of buoyancy on gas jet diffusion flames. [M Yousef Bahadori; R B Edelman; United States. National Aeronautics and Space Administration.]. Get this from a library.
Effects of gravity on laminar gas jet diffusion flames. [Thomas H Cochran; William J Masica; United States. National Aeronautics and Space Effects of buoyancy on gas jet diffusion flames book Lewis Research Center.] -- An experimental program was conducted to study the burning of laminar gas jet diffusion flames in a zero-gravity environment.
The tests were conducted in the Lewis Research Center Buoyancy Effects on Flow Transition in Hydrogen Gas Jet Diffusion Flames Burt W. Albers and Ajay K. Agrawal* School of Aerospace and Mechanical Engineering University of Oklahoma Norman, OK Abstract Experiments were performed in earth-gravity to determine how buoyancy affected transition from laminar to turbulentAuthor: Burt W.
Albers, Ajay K. Agrawal, DeVon Griffin. Transitional buoyant jet diffusion flames are investigated by 3D spatial direct numerical simulations (DNS).
To examine the fuel source and sidewall geometry effects, a comparative study has been. characteristics of gas-jet diffusion flames over the entire range of laminar, transitional, and turbulent regimes• Comparisons are also being made with the characteristics of the normal-gravity counterparts of these flames to determine the effects of buoyancy on these jet diffusion flames.
Analytical and numerical studies are also underway. Abstract. In order to investigate the effect of buoyancy on soot formation in gas-jet diffusion flame, we conducted one set of experiments with the High-Temperature Air Combustion Technology (HiCOT) system and another set under partial gravity by: 5.
It is shown that for jet-momentum-dominated diffusion flames, when the buoyancy effects are neglected, the flame length normalized by the burner exit diameter increases linearly with the Reynolds number at the burner exit in the laminar burning regime and decreases in inverse proportion to the Reynolds number in the transitional regime.
Transitional jet diffusion flames provide the link between dynamics of laminar and turbulent flames. In this study, instabilities and their interaction with the flow structure are explored in a transitional jet diffusion flame, with focus on isolating buoyancy effects.
Experiments are conducted in hydrogen flames with fuel jet Reynolds number of up to 2, and average jet velocity of up to 54 Cited by: This paper presented a numerical study of flow instability effects on the sound generation by jet diffusion flames.
Numerical simulation coupled with the acoustic analogy based on Lilley’s equation was employed to predict the sound : Caiyi Xiong, Yong Jiang. An experimental program was conducted to study the burning of laminar gas jet diffusion flames in a zero-gravity environment. The tests were conducted in the Lewis Research Center Second Zero-Gravity Facility.
The photographic results indicated that a sudden decrease in gravity level from 1 to 0 effected an immediate reduction in the length of the flame. The effects of changes in the jet nozzle geometry, i.e., nozzle shape and lip thickness, on the blowout limits of jet diffusion flames in a co-flowing air stream were experimentally investigated for a range of co-flow air stream velocities.
is very difficult in that the analyses involve fluid mechanics, diffusion, and buoyancy influences among others. A serious problem in constructing these models is that buoyancy effects tend to dominate and hide smaller effects present in a combusting gas. Flame studies done in the microgravity environment are very well suited to improve combustion.
Buoyant diffusion flames of natural gas were observed in wind tunnel experiments to determine the extent of bending by wind. The experimental results were correlated through use of a simple physical model for the gross flame structure.
Flame buoyancy was varied through changes in diameter of the natural gas burner nozzle. Nozzle velocity was held constant at a value comparable. Experiments indicate that jet diffusion flames become larger, more spherical, and sootier as gravity is reduced, but the mechanism is not yet fully understood.7 Preliminary data on spherically symmetric fuel droplet vaporization and burning support the theoretical prediction of the importance of certain unsteady effects.8 Buoyancy tends to.
The phenomena treated in this book all depend on the action of gravity on small density differences in a non-rotating fluid. The author gives a connected account of the various motions which can be driven or influenced by buoyancy forces in a stratified fluid, including internal waves, turbulent shear flows and buoyant convection.
This excellent introduction to a rapidly developing field. trailing diffusion branch is affected by buoyancy primarily due to the changes in the overall flame shape. The overall size of triple flame is determined by the two premixed branches.
Buoyancy affects the locations of these premixed flames and consequently modifies the rates of diffusion of excess fuel and oxidizer from the premixed branches to.
Some effects of buoyancy on EI C O were observed at lower jet exit velocities and the EI C O was the lowest for the burners with largest buoyancy flux. Elliptic burner flames produced greater peak flame temperature than the corresponding circular burner flames under most by: It is shown that for jet-momentum-dominated diffusion flames, when the buoyancy effects are neglected, the flame length normalized by the burner exit diameter increases linearly with the Reynolds number at the burner exit in the laminar burning regime and decreases in inverse proportion to the Reynolds number in the transitional by: 2.Archival Journal Papers/Book Chapter.
S.M. Cherry, and S.R. Gollahalli,"Effects of Buoyancy on Steady Gas Jet Diffusion Flames," Combustion Science and Technology, “Buoyancy Effects on Hydrogen Gas-Jet Diffusion Flames,” Invited Seminar, Oklahoma State University, January