Unsteady and quasi-steady regimes of the flow around an inlet tested in a hotshot wind tunnel

Results of numerical simulation of an unsteady flow in an axisymmetric inlet with internal compression, which was tested in a hotshot wind tunnel with a fixed-volume settling chamber, are reported. The present simulations reveal the main specific features of various regimes: unsteady regimes of wind tunnel and inlet starting, regime of a quasi-steady flow around the inlet in a started state at a supersonic flow velocity in the channel, and subsequent unsteady transition to the regime with a detached bow shock wave at the entrance at a subsonic flow velocity in the channel. A previously unknown regime of the flow around the inlet with wavy motion of the bow shock wave is observed. It is shown that vibrations decay with time, and the shock wave position in the incoming flow become stabilized at a certain distance from the leading edge of the inlet with the test flow regime in the wind tunnel being preserved.