Experimental study of scramjet cavity with rear edge slots and its performance in combustion enhancement

Abstract

To improve the effect of the traditional two-dimensional trapezoidal cavity in promoting mixing and combustion, a three-dimensional cavity with slots equipped on the cavity rear edge was proposed and investigated in a model supersonic combustor in this work. Experiments are conducted at a direct-connect test facility, where the traditional two-dimensional trapezoidal cavity (baseline) case and the slots cavity case are compared. The results show that the overall combustion along the combustor is intensified by the slots cavity. Specifically, the wall static pressure around the cavity increases by 6.1% at the lower injection pressure and 12.7% at the higher injection pressure. Based on the quasi-one-dimensional analysis, the estimated combustion efficiency increases by more than 20% due to the slots cavity. For the slots case, the combustion area and flamebase location are less affected by the injection pressure than that for the baseline case. As a result, the combustion that the slots cavity stabilizes is more stable than the combustion that the baseline cavity stabilizes. The increased exchange area, the bigger length-to-depth ratio, and the transverse flow and streamwise vortices induced by the slots may be responsible for the enhanced mixing and combustion.