Effect of inlet internal contraction ratio on performance of solid fuel scramjet

To investigate the interaction between inlet and combustor of solid fuel scramjet, various engine components were designed preliminarily at a design point of Mach number of 6 and altitude of 25 km. A series of engine models with different inlet internal contraction ratios were simulated numerically. Results show that when the inlet internal contraction ratio increases and combustor structure kept unchanged, the thrust and specific impulse of engine decrease rapidly and increase slightly; with the same area expansion ratio at combustor inlet, the overall performance of engine is improved as inlet internal contraction ratio increases. On the premise of inlet starting and flame holding, the inlet internal contraction ratio should be as large as possible, while the area expansion ratio at combustor inlet should be as small as possible in the engine design.