Numerical Investigation on the Effects of Cavity in Solid Fuel Scramjet

Abstract

This paper describes the numerical investigations concerning the characteristics of the flowfield in the solid fuel scramjet (SFSCRJ) and the rate of mixing or combustion enhancement when a cavity structure is used in the scramjet combustor. The goal of the paper is to study the influence of the cavity in the solid fuel scramjet, mainly about the length-to-depth ratio (L/D) of the cavity. The computational conditions of the numerical investigations are operated under the non-reactive conditions and reactive conditions respectively. The numerical investigations of the scramjet combustor concentrate on the appropriate structures for maximize mixing or combustion efficiency and minimum total pressure loss. The cavity effect is discussed from a viewpoint of mixing efficiency, total pressure loss and combustion efficiency. Compared with the combustor without cavity, the combustor with cavity is found to enhance the mixing efficiency apparently while decreasing the total pressure loss. It is noted that there exists an appropriate length-to-depth ratio (L/D) of the cavity regarding the mixing or combustion efficiency and the total pressure loss. Meanwhile, compared with the different length-to-depth ratio (L/D) of the cavity, the mixing and combustion efficiency is not monotonically increasing or decreasing with the variation of the length-to-depth ratio (L/D) of the cavity. So there exists a best length-to-depth ratio (L/D) to get the best performance of the combustor. The investigation of the cavity L/D ratio would provide some insight into the design considerations of cavity for solid fuel scramjet.