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Gravitational Effects on Cellular Flame StructureAn experimental investigation has been conducted of the effect of gravity on the structure of downwardly propagating, cellular premixed propane-oxygen-nitrogen flames anchored on a water-cooled porous-plug burner. The flame is subjected to microgravity conditions in the NASA Lewis 2.2-second drop tower, and flame characteristics are recorded on high-speed film. These are compared to flames at normal gravity conditions with the same equivalence ratio, dilution index, mixture flow rate, and ambient pressure. The results show that the cellular instability band, which is located in the rich mixture region, changes little under the absence of gravity. Lifted normal-gravity flames near the cellular/lifted limits, however, are observed to become cellular when gravity is reduced. Observations of a transient cell growth period following ignition point to heat loss as being an important mechanism in the overall flame stability, dominating the stabilizing effect of buoyancy for these downwardly-propagating burner-anchored flames. The pulsations that are observed in the plume and diffusion flame generated downstream of the premixed flame in the fuel rich cases disappear in microgravity, verifying that these fluctuations are gravity related.
Document ID
19920033986
Document Type
Conference Paper
Authors
Dunsky, C. M. (California Univ. Berkeley, CA, United States)
Fernandez-Pello, A. C. (California, University Berkeley, United States)
Date Acquired
August 29, 2013
Publication Date
January 1, 1991
Subject Category
INORGANIC AND PHYSICAL CHEMISTRY
Meeting Information
International Symposium on Combustion(Orleans)
Funding Number(s)
CONTRACT_GRANT: NAG3-861
Distribution Limits
Public
Copyright
Other