Application potential of periodically-forced air-jet vortex generators for separation control in supersonic flow*

Shock-induced separation occurs in numerous circumstances and has strong detrimental effects on the aerodynamic behavior and functionality of aerospace transportation and propulsion systems. The associated low-frequency unsteadiness of the shock/separation-bubble system can induce structural vibrations that may severely damage the structure, particularly for lightweight designs, which are not entirely structurally stiff. Among the many separation-control methods, steady air-jet vortex generators (AJVGs) show excellent effectiveness in reducing the separation length, both over rigid and compliant surfaces. However, experimental analysis with digital image correlation showed that the surface deflections induced by low-frequency shock motions over compliant surfaces can be amplified due to the influence of the AJVGs, which is an undesired side effect. First large-eddy simulations of periodically-forced AJVGs applied to control the large-scale separation induced in a 24° compression-ramp interaction over a rigid surface at Mach 2.5 demonstrate the capability of these devices to shift the oscillation frequency of the shock/bubble system. This behavior is promising regarding the application of such forced AJVGs to control shock-induced separation over compliant surfaces.