Hypersonic Oscillating Shock-Wave/Boundary-Layer Interaction on a Flat Plate

This work discusses the design, measurement, and simulation of an oscillating shock-wave/boundary-layer interaction on a flat plate at Mach 5.8 and Re∞=7×106 m−1. The shock generator is free to pitch and oscillates with a frequency of 42 Hz, resulting in a shock that varies in intensity and impingement point, with a maximum flow-deflection angle of approximately 10 deg. Transition appears to take place downstream of the separated region for both static (with a fixed flow-deflection angle) and dynamic experiments; however, heat-flux values are typically between laminar and turbulent solutions, thus suggesting that a complete transition to a fully turbulent boundary layer is delayed because of the favorable pressure gradient induced by the impinging expansion wave originating from trailing edge of the shock generator. Peak pressure is typically overpredicted by laminar simulations for large deflection angles. Starting from the reattachment point, heat-flux measurements show that the boundary layer gradually deviates from the laminar solution towards a fully turbulent boundary layer. Vortices are observed in the reattachment region, and their distribution is solely a function of the boundary-layer properties at the separation point. Transient effects induced by the shock motion result in a maximum bubble length variation of 30%. For the static cases, the separated region amplified disturbances with a frequency of approximately 200 Hz. In the dynamic experiment, harmonics induced by the pseudosinusoidal motion of the shock generator were measured everywhere on the plate.