Counterflow Drag Reduction Studies for a Blunt Cone in High Enthalpy Flow

Abstract

Drag reduction by counterflow supersonic jet for a 60-degree apex angle blunt cone in high enthalpy flow is investigated in a free piston driven hypersonic shock tunnel, HST3. For flow Mach number of 8 with specific flow enthalpy of 5 MJ/kg, it has been observed that the drag force decreases with increase in the ratio of supersonic jet total pressure to the freestream pitot pressure until the critical injection pressure ratio is reached. Maximum percentage drag reduction of 44 is measured at the critical injection pressure ratio of 22.36. Further increase in injection pressure ratio has reduced the percentage drag reduction. Experimentally obtained drag signals portray the change in nature of the flowfield, around the model, across the critical injection pressure ratio.