The Effect of Ambient Pressure on Flame Spread Over Thin Cellulosic Fuel in a Quiescent, Microgravity Environment

Results from recently conducted experiments on flame spread over a thin cellulosic fuel in a quiescent, microgravity environment of a 50/50 volumetric mixture of oxygen and nitrogen (oxygen mass fraction 0.53) at three different pressures—101, 152, and 203 kPa (1, 1.5, and 2.0 atm)—are analyzed. The results are compared with established theoretical results and two different computational flame spread models: one that includes gas-phase radiation, and one that does not. The spread rate behavior from experiment, i.e., an increase of spread rate with pressure, is consistent with the theoretical model that includes gas-phase radiation, and side-view photographs of the flames compare favorably with two-dimensional temperature contours produced computationally from the same model. In contrast, neither the dependence of spread rate on pressure nor the flame shape can be predicted with favorable comparison to experiment if radiation is neglected.