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Diffusive and Radiative Transport in Fires (DARTFire): Opposed-Flow Flame Spread in Low-Velocity FlowsFor flames spreading into a low-velocity flow that can only be obtained in microgravity, we have observed behavior that is different from that which is obtained at higher velocities where radiative effects are unimportant and species transport is relatively fast. Unfortunately, lack of a large body of low-gravity flame spread experimental data inhibits progress in developing an understanding of the physics of low-velocity, opposed-flow flame spread phenomena. Recent DARTFire sounding rocket experimental studies though, coupled with developing theory and modelling, have allowed some strides in understanding to be made, on which we report here. Four launches to date have resulted in six experiments for opposed-flow flame spread over a thick PMMA sample. During the 6 min microgravity period, the PMMA samples were ignited, and steady flame spread was studied under varied flow velocity, oxidizer atmospheric conditions, and, because radiative heat transfer is so important in these slowly spreading flames, external radiant flux. These were the first attempts at such experimental control and measurement in microgravity. A recent reflight of the Solid Surface Combustion Experiment (SSCE) has demonstrated, as modelling predicts, that for the thick fuel of the DARTFire experiment, flame spread in a quiescent environment is a transient process evolving from ignition to extinction on the order of 600 s (Altenkirch et al., 1999). Further study then of the effects of radiation in the very low-velocity opposing flows is of interest in understanding the transition from steady, sustained spread to the unsteady evolution to extinction as the opposing flow is reduced further and eventually removed.
Document ID
19990054038
Acquisition Source
Glenn Research Center
Document Type
Conference Paper
Authors
Altenkirch, R. A.
(Mississippi State Univ. Mississippi State, MS United States)
Olson, S. L.
(NASA Glenn Research Center Cleveland, OH United States)
Deering, J. L.
(Washington State Univ. Pullman, WA United States)
Tang, L.
(Mississippi State Univ. Mississippi State, MS United States)
Bhattacharjee, S.
(San Diego State Univ. San Diego, CA 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: NCC3-221
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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