EXPERIMENTAL INVESTIGATION OF AN AXISYMMETRICAL HYPERSONIC SCRAMJET INLET FOR LASER PROPULSION

A three-dimensional axisymmetric hypersonic engine inlet was investigated in the Rensselaer Polytechnic Institute Hypersonic Shock Tunnel at a Mach number range of 10-25 and at stagnation temperatures of 800-4100 K. Static and total pressures were measured at various positions along the forebody and within the cowled engine to obtain estimates of inlet performance and data for validation of a computational fluid dynamic (CFD) code. Schlieren and luminosity photographs of the flowfield were obtained to aid the interpretation of pressure data. Results indicate significant viscous effects on the now structure and resulting pressures. The Newtonian pressure distribution approximated the experimental results for the forebody well in general form, but the shock wave-boundary-layer interactions resulted in complex flow phenomena with pressure fluctuations on the vehicle surface that could not be predicted by the Newtonian theory. For ideal gas flows, the pressure recovery at the entrance of the heat addition region of the inlet was similar to that of an ideal 30 deg conical inlet.