Parametric numerical analysis on the interaction between combustion and hydrocarbon fueled supersonic film cooling

Film cooling is an effective method to achieve thermal protection and reduce skin friction for scramjet combustors. Gaseous endothermic hydrocarbon fuel is used as coolant and parallel injected into the supersonic boundary layer to generate a cooling film, and the combustion of the coolant film is introduced during the cooling process. Interaction between combustion and hydrocarbon fueled supersonic film cooling is numerically studied using Reynolds-averaged Navier–Stokes equations. An interesting result is that the flame of the coolant film in the boundary layer is formed apart from the wall. And the film coolant combustion brings double effects on the film cooling performance rather than only brings negative effects. Moreover, the skin friction is reduced through the film coolant combustion. The numerical results show that as the film injection velocity decreases or the wall temperature increases, the self-ignition point moves upstream, the perpendicular distance between the wall and the flame decreases, the flame moves towards the wall and even reaches the wall, which has significant effects on film cooling performance and skin friction. Furthermore, shock waves are generated after the ignition of hydrocarbon fuel due to the energy fluctuation of the combustion. The shock waves influence the skin friction distribution significantly.