Numerical Investigation on Cavity Length for Solid Fuel Scramjet

Abstract

The g oal of this study is to i nvestigate into the influence of the cavi ty for solid fuel scramjet (SFSCRJ) combustion performance, mainl y on the length-to-depth ratio(L/D) of cavity. Scientific visualizati on of the numerical simulations by the Shear Stress Transport (SST) k-ω model allows a detailed anal ysis of shocks and waves. A second-order-upwi nd computational flui d dynamics is used for simulating the dynamic flow associated with an axisymmetric, cavi ty i nstalled combustor under reacting condi tions. The combustor inlet condi tion airflow is set as Mach number of 1.6, total temperature of 1156 K and average air mass flow rate of 0.184kg/s. The soli d fuel uses the hydroxyl-termi nated-pol ybutadiene (HTPB) wi th a global one step reaction mechanism. Numerical simulations are confirmed by the experiments. The study concerns the combustion enhancement when a cavi ty is installed in the soli d fuel supersonic combustor. The pri mary emphasis is to exami ne the sensiti vity of the primary properties due to variations on the cavity L/D ratio ranging from 3-5. The cavi ty effect is discussed from a viewpoi nt of total pressure loss, combustion efficiency, thrust, specific thrust and s pecific impulse. The combustor with cavity is found to enhance combustion efficiency while de creasing the pressure loss, compared wi th the case without cavity. It is noted that there exists an appropriate length of cavity regarding the combustion efficiency and total pressure loss. The investigation of the cavity L/D ratio woul d provi de some insight into the design considerations of cavity for solid fuel scramjet.