Study on Flow Control Method in Isolator of a Wide-Range Ramjet Inlet

Flow control is one of the key technologies of a wide-range ramjet engine for the stable operation of its inlet. In this paper, the flow stabilization methods in the isolator of a ramjet inlet by shock train position control are studied. The control performance of the bleed and jet injection methods is discussed. Through numerical simulation, it is found that: 1) The control of bleed plays a positive role in the shock train control, and has better efficiency in conditions with high Mach numbers. 2) Injection at an appropriate small angle can blow off the boundary layer and effectively drive the shock train downstream in the isolator. But excessive injection angles will squeeze the flow passage, leading to a negative impact. 3) There is a critical pressure ratio of jet injection to make the shock train stand the most downstream in the isolator, and when the injection pressure surpasses it, the injection will have the opposite effect on the relevant flow control. 4) The supersonic jet injection has a more noticeable performance in high backpressure conditions, whilst its effect is slightly influenced by the jet injection pressure.