K. Nakabe et al., IGNITION AND TRANSITION TO FLAME SPREAD OVER A THERMALLY THIN CELLULOSIC SHEET IN A MICROGRAVITY ENVIRONMENT, Combustion and flame, 98(4), 1994, pp. 361-374
An axisymmetric, time-dependent model is developed describing auto-ign
ition and subsequent transition to flame spread over a thermally-thin
cellulosic sheet heated by external radiation in a quiescent micrograv
ity environment. Due to the unique combination of a microgravity envir
onment and low Reynolds number associated with the slow, thermally ind
uced flow, the resulting velocity is taken as a potential flow. A one-
step global gas phase oxidation reaction and three global degradation
reactions for the condensed phase are used in the model. A maximum ext
ernal radiant flux of 5 W/cm2 (Gaussian distribution) with 21%, 30%, a
nd 50% oxygen concentrations is used in the calculations. The results
indicate that autoignition is observed for 30% oxygen concentrations b
ut the transition to the flame spread does not occur. For 50% oxygen t
he transition is achieved. A detailed discussion of the transition fro
m ignition to flame spread is given as an aid to understanding this pr
ocess. Also, a comparison is made between the axisymmetric configurati
on and a two-dimensional (line source) configuration.