Non-Thermal Control of Shock-Wave Induced Boundary Layer Separation using Magneto-Hydrodynamics

Abstract

This study investigates the non-thermal impact of a magnetically driven surface discharges (“snow-plough” arc) on shock induced boundary layer separation. The surface plasma column appears as a transverse “arc” between two diverging electrodes which is driven by j x B force so that it sweeps the gas near the surface either in the downstream direction or in the upstream direction. Initial results have been reported previously using a Mach 2.8 indraft wind tunnel show that upstream forcing of boundary layer induced separation in the interaction zone of an oblique shock, generated by a 10 degree wedge, with turbulent boundary layer. This interaction, of oblique shock with boundary layer, is shown not to induce a recirculation bubble or separation in the boundary layer without plasma actuation. A 14 degree wedge is used to generate an oblique shock that impinged on the turbulent boundary layer generating a separation zone and recirculation in the flow. Downstream plasma actuation, against the recirculating flow, in such a case resulted in modified geometry of interaction zone as seen in Schlieren images. Various new configurations of plasma – flow interaction are developed, mainly applying magnetic field at an angle such that plasma column forces the core flow into the boundary layer increasing the momentum and thus avoiding separation.