Preliminary Exploration of Hypersonic Wind Tunnel Inlet Test Method

Test method for inlets in general hypersonic wind tunnel FD-07 are summarized, including force measuring test, pressure measuring test, heat flux measuring tests and control tests of boundary layer transition. Force tests, which are overall tests of air-breathing hypersonic flight vehicles, mostly measured the coupling effect of inlet internal flow and outer flow around the aircraft on the overall aerodynamic force when the inlets worked under different conditions. Force tests could also simulate flight height by regulating jet flow pressure ratio. With higher pressure ratio, normal force increased and axial force decreased. Pressure tests mainly simulated the inlet working condition in different compression ratios and back pressures, which could be used to observe the change of pressure in inlet starting, critical starting, and non-starting conditions and the inverse process. With back pressure rising, shock waves were pushed out of the cowl and once surge happened, the shock waves at the cowl concussed at an unstable condition. Heat flux measurement results in general hypersonic wind tunnels showed distinct characteristics of separated flow that sharp fluctuation of heat flux are presented on the surface of channel downstream the cowl. In the tests of boundary layer control, the addition of compulsive transition strip on the fore body compression surface could eliminate the separated region efficiently, thereby maintaining the inlets capability.