The unsteady numerical study of the mixed-compression inlet restarting flow with the single square pulse injection was performed.The results show that mass flow entering the inlet decreased and external normal shock is swallowed into lip with the joining of the injection on ramp

because of the blockage of the jet to incoming flow.As the mass flow of jet exceeds the threshold value of 5% of inlet mass flow

and the duration time of injection is less than 15ms

needing at least 0.0014kg gas for injection

the unstart flow of inlet will restart.And a high-frequency oscillation flow with 135Hz arises when the mass flow of jet is less lightly than the threshold value.The duration time for restart and total gas mass reduce with the increase of mass flow of jet because of the faster flow response when the mass flow of jet exceeds the threshold value.