Research progress review on hypersonic three-dimensional inward-turning inlet

The hypersonic three-dimensional inward-turning inlet has gradually become the preferred design for air-breathing vehicles due to its advantages of compact structure, high compression efficiency, high flow capture capability, high total pressure recovery coefficient, and ease of integration. Since the introduction of the inward-turning inlet concept, it has attracted extensive attention from scholars and research institutions worldwide. Firstly, focusing on the aerodynamic design and optimization of the inward-turning inlet, the recent advancements in shock wave analytic theory, basic flowfield construction, and inward-turning inlet design are summarized. Subsequently, the research on improving the performance of the inward-turning inlet under off-design conditions is introduced from the perspectives of low Mach number starting and anti-backpressure characteristics. The current application of the inward-turning inlet in TBCC combined propulsion systems is then discussed. Finally, based on the analysis and summary of the current research status at home and abroad, four key future research spots of the three-dimensional inward-turning inlet are pointed out.