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Effects of Buoyancy in Hydrogen Jet Diffusion FlamesThis project was carried out to understand the effects of heat release and buoyancy on the flame structure of diffusion flames. Experiments were conducted at atmospheric pressure in both normal gravity and microgravity conditions in the NASA LeRC 2.2 s drop tower. Experiments were also conducted in a variable pressure combustion facility in normal gravity to scale buoyancy and thus, to supplement the drop tower experiments. Pure H2 or H2 mixed with He was used as the jet fluid to avoid the complexities associated with soot formation. Fuel jet burning in quiescent air was visualized and quantified by the Rainbow Schlieren Deflectometry (RSD) to obtain scalar profiles (temperature, oxygen concentration) within the flame. Burner tube diameter (d) was varied from 0.3 to 1.19 mm producing jet exit Reynolds numbers ranging from 40 to 1900, and generating flames encompassing laminar and transitional (laminar to turbulent) flow structure. Some experiments were also complemented with the CFD analysis. In a previous paper, we have presented details of the RSD technique, comparison of computed and measured scalar distributions, and effects of buoyancy on laminar and transitional H2 gas-jet diffusion flames. Results obtained from the RSD technique, variable pressure combustion chamber, and theoretical models have been published. Subsequently, we have developed a new drop rig with improved optical and image acquisition. In this set up, the schlieren images are acquired in real time and stored digitally in RAM of an onboard computer. This paper deals with laminar diffusion flames of pure H2 in normal and microgravity.
Document ID
19990053991
Acquisition Source
Glenn Research Center
Document Type
Conference Paper
Authors
Agrawal, A. K.
(Oklahoma Univ. Norman, OK United States)
Al-Ammar, K.
(Oklahoma Univ. Norman, OK United States)
Gollahalli, S. R.
(Oklahoma Univ. Norman, OK United States)
Griffin, D. W.
(NASA Glenn Research Center Cleveland, OH United States)
Date Acquired
August 19, 2013
Publication Date
May 1, 1999
Publication Information
Publication: Fifth International Microgravity Combustion Workshop
Subject Category
Inorganic And Physical Chemistry
Funding Number(s)
CONTRACT_GRANT: NAG3-1594
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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