Viscous/Inviscid Interactions of the Forebody Flowfield of an Airbreathing Hypersonic Vehicle

A hypersonic cruise missile, which can be launched from conventional aircraft or from surface-based assets and which can cruise at a Mach number of 8, requires at least two propulsion systems: a rocket-based propulsion system and a supersonic combustion ramjet system. The inlet to the airbreathing propulsion system will be closed during that portion of the flight powered by the rocket-based propulsion system. As a result, a shock-wave /boundary-layer interaction will result when the supersonic flow on the forebody encounters the compression ramp formed by the closed inlet. To investigate the flowfield for this interaction, surface-pressure measurements and flow-visualization photographs have been obtained during an experimental program conducted in the Tri-Sonic Wind Tunnel at the U.S. Air Force Academy. Data were obtained at a freestream Mach number of 4.28 and at a freestream Reynolds number (based on the model length) of 12.79 x 10 exp 6 over an angle-of-attack range from -7.3 to +7.3 deg. The data are compared with computations made with version 3 of the General Aerodynamic Simulation Program. The three-dimensional viscous /inviscid interaction that occurs near the compression ramp contains transverse vortices and streamwise vortices, with pressures in the reattachment region being approximately an order of magnitude larger than those for the undisturbed flow upstream of the interaction. (Author)