Study on continuous incident compression waves/turbulent boundary layer interaction under the influence of an expansion corner

Numerical simulations were employed to investigate incident compression waves/boundary layer interactions under the influence of an expansion corner abstracted from high-speed supersonic inlets. As the incident compression waves migrate from upstream to downstream of the expansion corner, three distinct interaction patterns are identified based on the relative positions between the expansion corner and the incident compression waves, including interaction type I where the tailing compression wave remains upstream of the expansion corner, interaction type II where the expansion corner lies between the leading and tailing compression waves, and interaction type III where the leading compression wave impinges downstream of the expansion corner. Under inviscid conditions, the pressure distribution characteristics and the range of the incident compression waves along the wall were obtained for each interaction type, with predictive models for the range in interaction types II and III established through supersonic relations. Viscous simulations demonstrated that varying expansion corner angles and interaction types significantly affect wave structures around separation zones, pressure distribution characteristics, and separation zone scale. Pressure distributions conform to typical separated flow features for large separation cases. The separation zone scale showed consistent initial reduction followed by enlargement across different corner angles, which was explained by the inviscid analysis of the range of incident compression waves. Crucially, the relative positions between the sonic line and the wall were identified as a paramount factor for wave structures, enabling the development of flow models that elucidate the formation mechanisms of various wave patterns surrounding separation zones.