Abstract: The operation of the isolator of a scramjet is substantially affected by cowl induced shocks and corner expansion waves. The current study attempts to reveal the influence of these incident waves on the flow patterns and pressure recovery characteristics of the shock-train in the isolator. First, a simulation method for the incident shock and the corner expansion waves is advanced and validated with Achen wind tunnel experimental results in Germany. Then, the basic flow patterns of the shock-train with the influence of the incident shock waves are analyzed. The effect of the back pressure ratio and incident position of the cowl induced shock is also obtained. The results indicate that the supersonic core flow region of the shock-train deflects alternatively to the top surface and the bottom surface of the isolator with its upstream propagation because of the influence of the incident shock and reflected shocks. As compared with the case without incident shocks, the pressure gain across the shock-train is substantially decreased due to the incident shock waves. The pressure distribution deviates from the Waltrup empirical formula continuously with the rise of the incident point of the cowl induced shocks. The results obtained may provide a design guide for the integration of the inlet and the isolator.

Key words: shock-train, incident shock waves, corner expansion waves, isolator