Flame Spread Along Free Edges of Thermally Thin Samples in Microgravity.
Flame Spread Along Free Edges of Thermally Thin Samples
Mell, W. E.; Olson, S. L.; Kashiwagi, T.
Combustion Institute, Symposium (International) on
Combustion, 28th. Proceedings. Volume 2. July
30-August 4, 2000, Edinburgh, Scotland, Combustion
Institute, Pittsburgh, PA, Candel, S.; Driscoll, J. F.;
Burgess, A. R.; Gore, J. P., Editor(s)(s), 2843-2849 pp,
flame spread; microgravity
The effects of imposed flow velocity on flame spread
along open edges of a thermally thin cellulosic sample
in microgravity are studied experimentally and
theoretically. In this study, the sample is ignited at
the middle of the 4 cm width sample and subsequent flame
spread reaches both open edges of the sample. The
differing fates of the portions of the flame are
observed in the experiments and predicted by the
numerical calculation, in the order of increasing the
imposed flow velocity; (1) ignition but subsequent flame
spread is not attained, (2) flame spreading upstream
(opposed mode) without any downstream flame, and (3) the
upstream flame and two separate downstream flames
traveling along two open edges (concurrent mode).
Generally, the edge flame spread rate for both
directions is faster than the central flame spread rate
for an imposed flow velocity of up to 5 cm/s due to
enhanced oxygen supply from the outer free stream. For
the upstream flame, oxygen supply to the edge flame is
sufficient so that the edge flame spread rate is nearly
independent of or decreases gradually with the imposed
flow velocity. However, downstream edge spread rate
increases significantly with the imposed flow velocity.