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Influence of Buoyant Convection on the Stability of Enclosed Laminar FlamesAn investigation of the stability limits of Enclosed Laminar Flames (ELF) was conducted in the Middeck Glovebox (MGBX) facility on the STS-87 Space Shuttle mission (November to December 1997). The primary objective of the ELF glovebox investigation is to determine the effect of buoyancy on the stability of round, laminar, gas-jet diffusion flames in a co-flow air duct. Comparison tests were conducted in normal gravity to allow isolation and identification of the influence of buoyancy. The results were used to map the lift-off and blow-out stability limits as a function of the fuel and air velocities for the two buoyancy conditions. Approximately 50 tests were conducted during the Space Shuttle mission, using a 50/50 mixture (volume basis) of methane and nitrogen as the fuel. The experimental results verified the hypothesis that substantially greater velocities are required to destabilize the flame in microgravity. The increase in air velocity required to induce lift off in microgravity (compared to normal gravity) was nearly equal to the increase required to induce blow out. Furthermore, the air velocity increase was relatively independent of the fuel flow, except at low fuel flows. At high fuel flows, it was found that the microgravity flames tend to immediately blow out after lift off. This is in agreement with the free-jet theory which suggests that stable lifted flames are not possible for fuels with a Schmidt number of 0.5
Document ID
20000010697
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Brooker, John E.
(NASA Lewis Research Center Cleveland, OH United States)
Jia, Kezhong
(Iowa Univ. Iowa City, IA United States)
Stocker, Dennis P.
(NASA Lewis Research Center Cleveland, OH United States)
Chen, Lea-Der
(Iowa Univ. Iowa City, IA United States)
Date Acquired
August 19, 2013
Publication Date
September 1, 1999
Publication Information
Publication: Fourth United States Microgravity Payload: One Year Report
Subject Category
Inorganic, Organic And Physical Chemistry
Funding Number(s)
CONTRACT_GRANT: NAG3-1592
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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