Influence of air jet vortex generators on a supersonic shock wave / boundary layer interaction

Shock induced separation occurs in many air and space transportation applications. To alleviate its detrimental effects, we investigate the application of air-jet vortex generators for separation control. Small air jets induce longitudinal vortices in the boundary layer where they increase turbulent mixing. Consequently, the separation region decreases. We investigated a fully separated 24° compression ramp interaction at a flow Mach number of 2.5. Air jets are issued from circular orifices with a diameter of 0.1δ (incoming boundary layer thickness δ), inclined at an angle of 45° within the spanwise/wall-normal plane. The jet orifices are arranged in an equispaced line perpendicular to the main flow direction, and installed 8δ upstream of the ramp corner. The spanwise spacing was varied between 0.4 - 1.25δ and smaller spacings decrease the separation more effectively. The extent of the separation region was quantified from oil flow visualizations and we analyzed the control effect on the low-frequency shock unsteadiness based on sequences of focusing schlieren images. Mean and turbulent velocities are analyzed based on Particle Image Velocimetry measurements.