Effect of the flow rate of injected air on the temperature of porous wall in the supersonic flow

Abstract

The paper is devoted to the experimental analysis of the heat transfer during the injection of air through the porous wall in supersonic airflow. The effect of the injected gas flow rate on the distribution of the porous wall temperature along the mainstream is analyzed at a varying temperature of the injected gas in a wide range from +71.4∘C to −11.2∘C. Mach number of the mainstream equals two, while stagnation temperature equals +20.1∘C. Experimental results show that there is a temperature minimum in the distribution of porous wall temperature, depending on the flow rate of the injected gas. It is established that the particular effect of the injected gas flow rate on the heat transfer significantly depends on the injected gas temperature. The experimental results are analyzed using a simple phenomenological model, taking into account the dissipation of kinetic energy in the turbulent boundary layer, convective heat transfer due to gas injection, and heat transfer between the boundary layer and the porous wall. The competition between convective heat transfer in the turbulent boundary layer and heat transfer between the injected gas and porous wall results in the appearance of a minimum in the dependence of wall temperature on the injected gas flow rate.