Movement Characteristics of Shock Train Under Continuous Change of Incoming Mach Number

In order to study the movement characteristics of shock train with the variation of incident shock, a direct-connect wind tunnel experimental system with variable incoming Mach number was built. The movement behavior of shock train under the same change rate of incoming Mach number and different change rates of backpressure was captured. The influence mechanism of the synchronous change of incident shock and backpressure on the shock train movement was revealed. When the incident shock and the backpressure change at the same time, there are three factors that affect the overall upstream and downstream movement trend of the shock train. The first is the change of incoming Mach number. The increase of incoming Mach number leads to the downstream movement of the shock train, and the influence gradually weakens with the increase of the incoming Mach number. The second is the movement of the background waves. When the impingement point of the background wave approaches the shock train leading edge, the sudden jump of the shock train can be caused. The third is the change of backpressure ratio. When the backpressure ratio increases, the shock train moves upstream, and the influence gradually increases with the enhancement of backpressure ratio. The shock train exhibits complex movements under the coupling effect of the three factors.