Turbulent Transition Control Using Porous Surfaces in Hypersonic Boundary Layer

Hypersonic boundary layer on porous surfaces is simulated to investigate the effect of porous surfaces on the transition process. The fundamental breakdown involving the Mack second mode is computed using the direct numerical simulation (DNS) solver of Lim et al. (Comput Fluids 240:105437, 2022). Because it is computationally challenge to resolve numerous pores, the impedance boundary condition of a porous surface is pursued in this study to model the absorptive characteristics of a porous surface. The impedance boundary condition for a porous surface is implemented in the DNS solver and validated against relevant literature data. The stabilization of the Mack second mode on porous surfaces is well resolved in the current computations. Based on the validated numerical setup, 3D DNS computations of the hypersonic boundary layer over a porous surface are conducted. The current porous surface is optimized to absorb the Mack second mode. In this study, it is clearly shown that the turbulent transition involving the Mack second mode can be effectively delayed on the porous surface.