Control of incident shock wave/boundary layer interaction by concave surface

The separation induced by incident shock wave/boundary layer interaction (ISWBLI) in supersonic/hypersonic inlets significantly degrades aerodynamic performance. This study proposes a novel passive control method for ISWBLI by using a concave surface. Numerical simulations were employed to elucidate the flowfield under the influence of the concave surface, thereby validating the effectiveness of the control method. The results demonstrate that the concave surface generates beneficial expansion waves and precompression effects, which collectively attenuate the separation region both upstream and downstream of the shock impingement point. Specifically, the results show substantial separation size reduction, with upstream concave surface placement achieving 49.1% suppression and downstream configuration yielding 39% reduction. The near wall airflow exhibits distinct interaction patterns depending on geometric positioning. The effectiveness of control is observed in two distinct regions. The first effective region occurs when the initial position of the concave surface is located upstream of the reattachment point of the separation region, extending until the shock impingement point reaches the leeward expansion side. The second region is characterized by the shock impingement point being situated on the windward expansion side, continuing until the end position of the concave surface is downstream of the separation point. Conversely, shock impingement on the concave compression surface intensifies shock strength and exacerbates separation. A critical finding reveals that maximal mitigation of the adverse pressure gradient occurs when the shock impingement point is displaced a distance d1 from the initiation point of the concave surface, or proximate to the end of the concave surface.