Change of flow patterns in a supersonic inlet during its acceleration and deceleration

Abstract

The question of the ambiguity of the flow in a supersonic air inlet is analyzed: a) if a normal shock is formed in the internal compression channel, then a change in the flight speed does not allow removing the normal shock and create a supersonic flow; b) if the flow in the internal compression channel is supersonic, then an supersonic inlet remains starting and allows a significant decrease in flight speed up to the limit of isentropic compression. To clearly demonstrate the indicated two-valued nature of the flow, a numerical simulation of the acceleration and deceleration of the internal compression supersonic inlet was performed with the area ratio F2/F0 = 0.556. The calculation results show that during acceleration from M0 = 1.0, a normal shock is formed at the supersonic inlet and the unstarting of the supersonic inlet remains until the end of the calculation range (up to M0 = 2.6). If the supersonic inlet is started in any way at high supersonic flight speeds, then when deceleration from M0 = 2.6, it maintains a start mode up to M0 = 2.1, which corresponds to the permissible limit of isentropic compression