Numerical Investigation of Hypersonic Wall- Bounded Shear Flows – Part 1: Effusion Cooling

Direct numerical simulations (DNS) are carried out to study the laminar stability properties of an effusioncooled adiabatic flat-plate boundary layer at Mach 6. Through four aligned rows of holes, cold gas is blown into the boundary layer at the wall and background disturbances are excited at the wall upstream of the holes. Two cases are compared, with small and large spanwise spacing of the holes. Despite strong localized vortex-like flow deformations in both cases no strong “secondary” instability sets in. From studies of incompressible cases it is known that wall blowing can strongly destabilize the boundary layer. Thus an “incompressible” reference case (Mach 0.6) is simulated and compared with the effusioncooled Mach-6 case. Differences are found indicating that the high Mach number has a stabilizing effect on the young effusion-cooled boundary layer.