Control of SWBLI in a 24deg Compression Ramp Flow with Air-jet Vortex-generator

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. Implicit large-eddy simulations of an uncontrolled and AJVG-controlled SWBLI in a 24deg compression ramp flow was performed to examine the influence of spanwise-inclined jet injection on SWBLI. The oncoming boundary layer is at Mach 2.5 with a momentum-thickness Reynolds number of 7000. Spanwise-inclined jet injection embeds asymmetric counter-rotating vortex pair (CVP) in the boundary layer. The jet-induced major CVPs energize the nearwall region of the boundary layer, resulting in a 25% reduction of the separation length. Due to stronger downwash caused by the favorable interaction among the adjacent major CVPs, recirculation region in an AJVG-controlled SWBLI is 3D, with corrugated flow separation and local reattachment zones in the interaction region. Mean flow breakdowns and reorganizes, resulting in the formation of Görtler-like vortices in the interaction region for both uncontrolled and AJVG-controlled cases. However, additional momentum introduced by the injection of jets, results in an enhanced momentum distribution by Görtler-like vortices, leading to an early flow reattachment and flow homogenization in the AJVG-control case. Dynamic mode decomposition of the flowfields indicate similar key characteristics of SWBLI for both cases. The low-frequency unsteadiness is an intrinsic property of the SWBLI with influence of both upstream and downstream mechanisms. The entrainment of the mixing layer and the major CVPs influence the dynamics of the recirculation region in the AJVG-control case, indicating an increased upstream influence in comparison to the uncontrolled baseline case.