Effects of Transpiration Cooling on Hypersonic Boundary-Layer Receptivity and Stability for Blunt Cones

View Video Presentation: https://doi.org/10.2514/6.2023-3673.vid Peak heating rates are typically encountered in the nose region of flight vehicles traveling at hypersonic speeds. To reduce the heat transfer to the underlying structure, transpiration cooling can be incorporated by employing gas injection, especially in areas of the vehicle with high heat transfer rates, such as leading edges and nose regions. This study aims at understanding how transpiration cooling applied in the nose region only as well as additional application further downstream affect the receptivity mechanisms and stability characteristics of a Mach 9.81 flow around a blunt cone. Gas injection alters the boundary layer profiles mainly by increasing the boundary layer thickness for the cases where the injection extends downstream of the nose. When limiting gas injection to the nose region the effects on transition are negligible. However, adding injection downstream of the nose region can stabilize and severely destabilize the flow depending on the injection rates used. Generally, gas injection leads to the unstable region moving upstream and towards lower frequencies due to the thickening of the boundary thickness.