Recent advances in the aerothermodynamics of spiked hypersonic vehicles

Forebody shock control devices for drag and aero-heating reduction: A comprehensive survey with a practical perspective

The influence of steady energy addition into the flow by a low-voltage DC-arc discharge located upstream of conically nosed and spherically blunted bodies was investigated experimentally in the Ludwieg-Tube Facility at Mach 5. The results include drag force measurements and shadowgraph flow visualizations. The flow-field structure, arising due to the bow-shock/heated-wake interaction, as well as the bow-shock intensity and heating power effects on the drag reduction is analyzed in this paper. The results demonstrate the existence of an optimum heating rate, providing a maximum effectiveness of energy addition and showing distinct drag reductions up to 70% dependent on test conditions and model geometries.

Effects of steady flow heating by arc discharge upstream of non-slender bodies

Reduction in aerodynamic drag for a large angle blunt cone flying at hypersonic Mach number by heat addition into the shock layer is demonstrated in HST2 hypersonic shock tunnel. The heat addition is achieved by the exothermic reaction of chromium atoms ablated from the stagnation region of the chromium coated blunt cone with the atomic oxygen behind the shock wave. The measurements show about 47% reduction in the drag coefficient for a 60° apex angle blunt cone in a Mach 8 flow of 3.4 MJ/kg specific enthalpy. The reduction in drag is measured using the accelerometer based force balance system and the heat addition into the shock layer is identified by the surface mounted thin film heat flux gauges and the corresponding movement of the shock wave is visualized by schlieren pictures.

Aerodynamic drag reduction by heat addition into the shock layer for a large angle blunt cone in hypersonic flow

Counterflow drag reduction by supersonic jet for a 60° apex angle blunt cone flying at hypersonic Mach number is investigated for two different flow enthalpies using conventional and free piston driven hypersonic shock tunnels. Enhancement in drag reduction has been observed with increase in freestream stagnation enthalpy. It is shown that the percentage of drag reduction goes up by a factor of 2 when the flow enthalpy increases by a factor of 2.5 for a given ratio of total pressure of supersonic jet and freestream flow.

G. Srinivasan

Papers

Drag Reduction of Spiked Missile by Heat Addition