Effects of a porous coating on hypersonic boundary layer receptivity over a Cone

The effects of ultrasonically absorptive porous coating on receptivity and stability properties of hypersonic boundary layers are numerically investigated for boundary layer flows over a 5-degree straight cone at a freestream Mach number of 6.0. To compute the shock and the interaction of the shock with the instability waves, we solve the Navier-Stokes equations in axisymmetric coordinates. In the governing equations, inviscid and viscous flux vectors are discretized using a fifth-order accurate weighted-essentially-non-oscillatory (WENO) scheme. A third-order accurate total-variation-diminishing (TVD) Runge-Kutta scheme is employed for time integration. After the mean flow field is computed, acoustic disturbances are introduced at the upstream end of the computational domain. The appearance of instability waves near the nose region on solid and porous wall, and the receptivity of the boundary layer with respect to slow mode acoustic waves are investigated. Preliminary results confirm the stabilizing effect and the role of porous coating in the delay of boundary layer transition.