Experimental and Numerical Simulation of Shock Train Characteristics in the Concave Channel

Wind tunnel experiments were conducted on the concave and rectangular channels under incoming Mach numbers of 1.85 and 2.70. In the concave channel, the shock train structure leaned toward the concave wall, whereas a large flow separation existed on the flat wall. Sweeping the shock train leading edge abruptly increased the pressure, with the downstream pressure in the swept area increasing approximately linearly until it stabilized. The energy of the pressure fluctuations caused by the interaction between the shock train and boundary layer in the channel was concentrated in the frequency range of 2–1000 Hz. Compared to the rectangular channel, the shock train structure in the concave channel leaned toward the concave side with enhanced asymmetry. The anti-backpressure ability of the concave channel was stronger than that of the rectangular channel. The same change in the blockage ratio caused the shock train in the concave channel to move over a longer distance than in the rectangular channel. The stronger resistance to backpressure of the boundary-layer fluid in the concave channel results in stronger single shock waves in the shock train flowfield, with flow separation occurring closer to the downstream.