Control of the oscillations of shock train using boundary layer suction

Abstract

The isolator plays a major role in the scramjet engine by providing suitable pressure for the combustion process. It is situated between the inlet and the combustion chamber. The deceleration of supersonic flow into subsonic flow is achieved by a series of bifurcated normal shock waves referred to as “shock train”. The flow field is more complex with shock–shock interaction and shock boundary layer interaction. The presence of such flow inside the isolator can degrade the performance of the scramjet engine. The present study focuses on the self-excited shock train flow in an isolator and its control by partial removal of the boundary layer. The results examine the variation of the inlet to outlet pressure ratio with and without suction flow control. Numerical results indicate that the boundary layer suction will cause downstream movement of the shock train and the length of the shock train is reduced. The transformation of the shock train into a single curved normal shock is observed when the shock train present closer or upstream of the suction slot region. The obtained result shows the self-excited oscillation frequency in the range of 14-15 Hz. The suction control provides an advantage by 50% reduction in the amplitude of the shock train movement.