A kind of back pressure simulation technology by cavity injection is brought forward to improve wind tunnel test capability for hypersonic inlets.During wind tunnel test process

the back pressure of inlet can be adjusted rapidly by regulating the valve of injection pipe.Utilizing this specific simulation technology

the performance at different back pressures and the unstarting/restarting characteristics of an axisymmetric inlet are investigated.The design Mach number of the inlet is 7.0.Results indicate:(1) The newly developed simulation technology can form fairly average and easily controllable back pressure downstream the inlet

so it can be used to investigate the back pressure characteristics of hypersonic inlets.(2) By regulating the valve of injection pipe

the simulation technology can realize the switch of hypersonic inlet started state and unstarted state in about 8 milliseconds

so it is suitable to investigate the starting/unstarting/restarting problem of hypersonic inlets.