Mechanisms of pressure-wave feedback and shock evolution during transient opening of a supersonic inlet

Abstract

Transient shock evolution, pressure-wave dynamics, and shock-wave/boundary-layer interactions (SBLI) induced by moving boundaries are investigated during the opening process of a supersonic inlet. A dynamic-mesh-based numerical framework is developed to couple the rotational motion of the inlet cover with the unsteady compressible flow field. Using an integral solid rocket ramjet as a representative application, the effects of rotational inertia, spring preload, and incoming Mach number are systematically examined. The results show that inlet-cover motion is governed primarily by aerodynamic loading, with aerodynamic torque remaining substantially larger than both the spring-preload torque and gravitational moment throughout the opening process. Rotational inertia is identified as the dominant structural parameter. Although it does not alter the sequence of transient shock evolution, it changes the characteristic timescale of moving-boundary evolution and regulates the synchronization among geometric opening, shock evolution, pressure-wave propagation, and SBLI development. In contrast, spring preload only slightly modifies the opening history and has little influence on the subsequent transient flow evolution. Within the investigated range of Ma = 2.8–3.2, the incoming Mach number exhibits the strongest influence on transient shock evolution among the parameters considered. Increasing Mach number enhances aerodynamic loading and flow compressibility, accelerating moving-boundary evolution, pressure-wave propagation, and SBLI development, thereby promoting earlier shock displacement and stronger flow separation. The results further demonstrate that SBLI acts as the key intermediary mechanism linking pressure-wave propagation to transient shock evolution. Overall, transient flow evolution is governed by the coupled interaction between moving-boundary evolution and internal compressible-flow dynamics, providing new physical insight into moving-boundary compressible flows under time-varying geometric constraints.