Broadband design of acoustic metasurfaces for the stabilization of a Mach 4 boundary layer flow

Abstract A piecewise acoustic metasurface is designed to suppress the first mode while marginally amplifying Mack second in a Mach 4 flat-plate boundary layer (BL) flow. The results of linear stability theory (LST) and e N method demonstrate stabilization effect transition delay performance, respectively. However, direct numerical simulation (DNS) indicate that broadband actually weakly excites with slightly larger fluctuating pressure amplitude at surface, which contrast analysis LST. discrepancies are found lie ‘roughness’ caused by recirculation zones inside microslits alternating expansion compression waves induced slit edges, significantly amplifies mode. For further clarification competitive mechanism between destabilization effects metasurfaces on mode, carefully installed maximum growth rate region, but inhibits its development downstream.