Leading-edge bluntness effects in hypervelocity flat plate flow

The combined effects of leading-edge bluntness and high enthalpy are examined for hypersonic flat plate flow. Experimental pressure and heat transfer data are presented for both sharp and blunt leading-edge flat plates. For the sharp leading-edge flows, the data are in agreement with perfect gas theory. For the blunt leading-edge flows, the low and high enthalpy pressure data approach the perfect gas blast wave theory as the flow proceeds downstream, consistent with earlier studies at low enthalpy. Toward the front of the plate, the heat transfer data lie above the corresponding values obtained with the sharp leading-edge configuration. The difference between sharp and blunt leading-edge heat transfer levels appears to be smaller at high enthalpy. This seems to be due to dissociation which occurs in the nose region, thus reducing the shock stand-off distance and increasing the chemical potential enthalpy of the flow. When the presence of dissociated species in the flow is accounted for, the data close to the leading-edge are seen to compare well with perfect gas bluntness-viscous similitudes. Farther downstream, the measured heat transfer values are greater than the perfect gas theoretical predictions for blunt leading-edge flow, and closer to both the corresponding predictions at chemical equilibrium, and sharp leading-edge theory for perfect gas flow.