Separation Criterion in Hypersonic Swept Shock Wave/Turbulent Boundary Layer Interaction

The flow characteristics of fin-induced hypersonic swept-shock-wave/turbulent-boundary-layer interaction have been studied at a Mach number of [Formula: see text] and a moderate inflow Reynolds number of [Formula: see text]. By means of Reynolds-averaged Navier–Stokes (RANS), the interactions have been systematically analyzed under different cooled-wall conditions. Generally, the flow exhibits quasi-conical symmetry and reveals a complex separation structure, including primary and secondary separation regions. Both separation and reattachment behaviors can be quantified based on the proposed key parameters. The wall thermal effects have been discussed, and the findings exhibit a certain thermal sensitivity. As the temperature decreases, the separation region is weakened, and quasi-conical symmetry is more difficult to achieve. The primary separation seems to be less sensitive to the wall thermal condition, while the secondary separation region displays non-monotonic temperature dependence, whose size initially increases and then decreases as the temperature rises. The separation behavior is discussed in detail, including the flow features at different stages for primary and secondary separations. The high-pressure region around the primary reattachment would affect the reverse-flow region, causing acceleration and near-wall-normal shock, which would finally result in secondary separation.