Control of a Supersonic Compression-Ramp Interaction with Air-Jet Vortex Generators

Motivated by the beneficial effects of air-jet vortex generators (AJVG) in controlling shock-induced flow separation, we aim at understanding the underlying physics behind their effectiveness and their influence on the shock-wave/boundary-layer interaction (SWBLI) dynamics. Implicit large-eddy simulations of uncontrolled and AJVG-controlled SWBLIs at a 24 deg compression ramp were performed. The oncoming turbulent boundary layer at Mach 2.5 had a momentum-thickness Reynolds number of 7000. The spanwise inclined AJVGs were arranged in a line array and installed 8 boundary-layer thicknesses δ upstream of the ramp corner. Spanwise-inclined jets induce asymmetric counter-rotating vortex pairs (CVPs) in the boundary layer. These major CVPs enhance the momentum redistribution within the boundary layer and energize the near-wall region, resulting in a 25% reduction in separation length. Favorable interactions among adjacent major CVPs increase downwash in between devices. Consequently, the recirculation region becomes 3D, with corrugated separation and local reattachment zones. A dynamic mode decomposition analysis indicates similar key characteristics for both the baseline and controlled SWBLIs, namely, that the SWBLI dynamics are dominated by the low-frequency unsteadiness of the separation bubble/shock system. The AJVG-induced major CVPs influence the dynamics of the recirculation region but do not fundamentally alter them.