Comparison of the unstart/restart processes of a two-dimensional twin-duct supersonic inlet induced by the plug throttling and thermal choking at the sideslip state

Abstract

It is of great significance to study the hysteresis phenomenon in the unstart/restart process of supersonic inlets for restart control in the practical operation of ramjet engines. In this paper, the unsteady numerical simulations are conducted for the unstart/restart processes of a ramjet engine with a two-dimensional twin-duct inlet configuration under asymmetric incoming-flow conditions (Ma0 = 2.6,β = 2°), and the unstart/restart characteristics of the inlet caused by the plug throttling and the thermal choking are compared and analyzed. The results show that from the perspective of source incentives, the hysteresis loop of the restart process of the leeward inlet caused by the thermal choking is larger than that of the restart process of the leeward inlet caused by the plug throttling, which indicates that it is difficult to verify the restart performance of the ramjet with the two-dimensional twin-duct inlet configuration in the actual operating process by the inlet's plug-throttling experiment in the conventional wind tunnel. In addition, in the practical operations, the increase of fuel gas causes the transition of the leeward inlet to the unstart state, and part of the fuel gas reacts and combusts stably on the external compression surface of the leeward inlet, which easily leads to the burning of the inlet if there is without any special thermal protection.