Supersonic turbulent boundary layer separation control using a morphing surface
Separated flows arising due to shock wave turbulent boundary layer interactions can cause problematic low frequency unsteadiness with potentially severe structural response. High-fidelity large eddy simulations are employed to examine surface morphing as a way to reduce the size of the separation region, and thus favorably alter the unsteadiness characteristics. The configuration considers a turbulent Mach 2.7 flow at Reynolds number Re = 54600, subjected to an impinging shock system of pressure ratio p 3 /p 1 = 3, which results in separation and the presence of structurally relevant low-frequency unsteadiness. The control surface, centered about the shock impingement location and extending over the separation region, is allowed to deform under material property-based realizability constraints, until an asymptotic state is achieved. The criterion for deformation uses a measure proportional to the directional surface shear-stress. At asymptotic state, the deformed surface reveals a shape consistent with aero-structural optimization and a maximum height of 0.32δ in . Control mitigates the sharp initial pressure gradient of the uncontrolled flow to delay and reduce separation extent (by 50%), with diminution of low frequency content and turbulent kinetic energy. Modal decomposition highlights these effects in the energy content of the prominent modes. Morphing may thus provide a means to adjust the local surface deflection in a manner that reduces some of the problems associated with turbulent separation.