Design method of hypersonic inward turning inlet based on genetic and gradient hybrid optimization strategy

The hypersonic inward-turning inlet has attracted wide attention because of its higher compression efficiencyand larger flow coefficient. Nowadays, traditional design methods cannot achieve the optimal performance of the inlet. Therefore, coupling the genetic algorithmand the gradient algorithm, this paper proposes a new design method for the hypersonic inward-turning inlet based on the hybrid optimization strategy, and completes the design of the inlet at Mach number 6. Firstly, the global configuration design of the basic flowfield is conducted using genetic optimization, resulting in a Pareto front of basic flowfields with good performance. Among them, a typical dual-shock wave basic flowfield is selected to design the dual-shock wave inward-turning inlet. Secondly, the refined shape design of the above inlet is carried out based on adjoint gradient optimization, which further improves the performance of the inlet. Consequently, compared to inward-turning inlets designed using the traditional forward design methods, the performance of the inlet constructed by the design method is significantly improved. The flow coefficient, total pressure recovery coefficientand pressure rising ratio are increased by 2.33%, 13.15%and 7.90%, respectively, and the distortion coefficient (DC₆₀) is reduced by 3.70%. During the global configuration design, the overall parameters of the basic flowfield, such as the radius of the center bodyand outlet, are designed to obtain the optimal-performing global configuration of basic flowfield. During the refined shape design, the fluctuations of the inlet surface improve the mass capture performanceand compression capability of the shock wave in the isolation section. In addition, the surface deformation also weakens the total pressure loss caused by the second incident shock wave, the development of streamwise vortexesand the flow separation induced by shock-wave/turbulent-layer interaction in the isolation section. Furthermore, the weakening of streamwise vortexesand flow separation results in the reduction of total pressure loss in the isolation sectionand the improvement of flow uniformity on the outflow boundary.