Numerical Simulation on Flow and Heat Transfer Characteristics of Film/Regenerative Compound Cooling Process

Abstract

Film cooling is an effective method to achieve reliable thermal protection and reduce skin friction for scramjet combustors. This paper analyzed the effects of incidence angle, blowing ratio and injection distance on flow and heat transfer characteristics of subsonic and supersonic film cooling. The results show that the incidence angle of 30° can achieve optimum cooling effects for both subsonic and supersonic film cooling in the present conditions. And there is a critical blowing ratio (0.8) and momentum ratio (2.0) within the critical distance where the wall-attachment ability of the cooling film suddenly weakens, and the temperature of the inner wall rises, but after this location, the film cooling efficiency increases monotonously with the increase of the blowing ratio and momentum ratio. And the film cooling can significantly increase the surface convective heat transfer coefficient, but decrease the temperature difference between the fluid and the wall more significantly, which results in a decrease of total wall heat flux.