Effect of a supersonic counterflow jet on blunt body heat transfer rates for oncoming high enthalpy flow

Abstract

Heat transfer reduction studies, in the presence of a supersonic counterflow jet from the stagnation point of a 60-deg apex angle blunt cone, are conducted in a free piston driven hypersonic shock tunnel, HST3, to verify the effectiveness of this technique for high enthalpy flows. For flow of Mach number 8 with stagnation enthalpy of 5 MJ/kg, it has been observed that the heat transfer rate at some location decreases initially with increase in the injection pressure ratio until the critical injection pressure ratio is reached. A forty-five percent reduction in heat transfer rate near the stagnation point has been measured for the critical injection pressure ratio, equal to 14.91. A further increase in the injection pressure ratio reduces the overall percentage heat transfer reduction. The dependence of fluidic spike length on percentage heat transfer reduction has been confirmed.