Large Eddy Simulation of the flame stabilization process in a scramjet combustor with rearwall-expansion cavity

Large Eddy Simulation (LES) was employed to study the flame stabilization process in a hydrogen fueled scramjet combustor with a rearwall-expansion cavity. The numerical solver was first validated for a reactive flow, the scramjet combustor with rearwall-expansion cavity case, and the numerical results were shown in good agreement with the available experimental data. Effects of different cavity configurations and equivalence ratios on the flame stabilization process were then studied. It was found that during the combustion process, the most concentrated heat release regions are all located near the cavity rear wall. Besides, the majority of heat release regions are existed in the supersonic zones and attached to the sonic lines. The flame distribution in the combustor is sensitive to the equivalence ratio, and a thin flame would be formed when further decreasing the equivalence ratio. At the same equivalence ratio, the cavity with lower rear wall will delay the occurrence of chemical reaction and form a more concentrated and intense heat release region downstream the cavity, which will accelerate the chemical reaction and also achieve a sufficient combustion in the combustor. For the rearwall-expansion cavity, both the cavity configuration and equivalence ratio should be combined to optimize the flame stabilization process in the combustor. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.