Abstract: A computational model of flame spread down a thermally thin solid combustible in microgravity environment has been proposed in this paper. Based on the solid fuel heat transfer and pyrolysis processes, the gas-phase combustion kinetics processes have been studied, and the mathematical treatment of interfacial coupling has been given here. The three--dimensional ullsteady processes of flame spreading in an enclosed chamber have been studied with numercial methods for the first time. The gravitional accelerat...