SINOPSIS

The streamwise back and forth movement of the separation bubble, triggered by the shock wave/boundary layer interaction (SBLI) at large Mach number, is known to yield wall pressure and aerodynamic load fluctuations. Following the experiments byWang et al. (2012), we aim to evaluate and understand how the introduction of microramp vortex generators (mVGs) upstream the interaction may reduce the amplitude of these fluctuations. We first perform a reference large eddy simulation (LES) of the canonical situation when the interaction occurs between the turbulent boundary layer (TBL) over a flat plate at Mach number M = 2.7 and Reynolds number Re_θ = 3600 and an incident oblique shock wave produced on an opposite wall. A high-resolution simulation is then performed including a rake of microramps protruding by 0.47δ in the TBL. In the natural case, we retrieve the pressure fluctuations associated with the reflected shock foot motions at low-frequency characterized by St_L = 0.02−0.06. The controlled case reveals a complex interaction between the otherwise two-dimensional separation bubble and the array of hairpin vortices shed at a much higher frequency St_L = 2.4 by the mVG rake. The effect on the map of averaged wall-shear-stress and on the pressure load fluctuations in the interaction zone is described with a 28% and 9% reduction of the mean separated area and pressure load fluctuations, respectively. Furthermore, the controlled SBLI exhibits a new oscillating motion of the reflected shock foot, varying in the spanwise direction with a characteristic low-frequency of St_L = 0.1 in the wake of the mVGs and St_L = 0.05 in between.