With a focus on the shock oscillation phenomenon of a supersonic inlet at a high Mach number, the influence of isolator overflow on shock oscillation is studied in this paper. The shock wave dynamic model with overflow was established by the theoretical method, and the integrated numerical model of internal flow and external flow in the inlet was established too. The theoretical analysis of rate of overflow and overflow position on the flow field is carried out, and the changes of flow field parameters are studied by numerical simulation under different overflow positions. The results showed that both increasing the rate of overflow and setting the overflow gap close to the shock front were beneficial to reducing the flow parameters’ oscillation. In the viscous flow field, the overflow gap restricted the forward development of the local separation region of the shock train system, thus constraining the shock wave movement process, which could significantly reduce the parameter oscillation. In model C with two groups of overflow gaps, pressure oscillations of sampling point P_U8 and P_L8 were reduced to 29.81% and 30.56% relative to without overflow, and the corresponding rate of overflow was within 3.6%, which indicated that the appropriate overflow gap setting could effectively suppress the self-excited oscillation in the inlet.

According to the requirements of a wide speed range, a variable-geometry supersonic inlet with inner surface adjustment is studied. The basic design model of the inlet is established, and the influence of profile adjustment on the resisting back pressure ability and inlet performance boundary are analyzed using a theoretical method. Based on the numerical simulation method, the flow field simulation is carried out, and the flow field parameter distribution and performance of the adjustment inlet are studied in comparison with the fixed-geometry scheme. The results show that the starting Mach number is not changed for two inlet schemes because they have the same profile during low-speed flight. The fixed-geometry inlet has insufficient compression on the incoming flow, and the resisting back pressure ability decreases significantly during high-speed flight. The compression ratio and the compression wave system can be easily changed at the same time through the adjustment of the inner profile for the adjustable inlet during high-speed flight. Both the theoretical analysis and numerical simulation show that the resisting back pressure ability and performance are significantly improved after the adjustment. As such, the adjustment method in this paper can fundamentally solve the problem of the insufficient compression of the wide-range working inlet during high-speed flight, and the method can be easily realized.