Abstract
In order to classify the flame spread behavior over a thermally thin material against the opposed flow, scale analysis was conducted and the results were compared with those of drop experiments. Two dimensionless number, Rrad and Da, which represented the radiation loss factor and the Damkohler number, respectively, were introduced to estimate the transition flow velocity from the thermal-regime to the microgravity-regime or the kinetic-regime in a given oxygen level. The result of scale analysis showed that the thermal-regime, in which the flame became most robust, located in low ambient flow condition. This predicted that the robust flame could exist in microgravity with a mild flow. The result of the drop experiment agreed with the prediction; the flame spread in CO2 balance condition was observed even at 21% oxygen level in microgravity whereas the downward spread was impossible at the same oxygen level.
