Effect of the streamwise pulsed arc discharge array on shock wave/boundary layer interaction control

The streamwise pulsed arc discharge array (S-PADA), in which five actuators are connected in series with adjustable frequency, is employed to control the shock wave/boundary layer interaction (SWBLI) at a 24 degrees compression ramp in a M = 2.0 flow and under two Reynolds numbers based on boundary layer thickness (Re-1 = 46 800 and Re-2 = 11 700). High-speed schlieren imaging at 50 000 fps is used for flow visualization. The schlieren snapshots, as well as the statistics of the image sequence, namely, mean and root-mean-square, are examined to reveal the control outcome. The results show that the separated wave foot gradually presents bifurcation and partial disappearance under Re-1 with the increasing pulse number of the S-PADA, indicating the decline in the shock intensity. The increase in frequency does affect the control outcome remarkably because shock weakening effect can be achieved under Re-1 through 10 kHz and 20 kHz actuations, while no obvious change can be observed by the 5 kHz actuation. The experiments under Re-2, where little control effect is exerted by the same methods, are also discussed. It is believed that the separated wave under a lower Reynolds number of Re-2 presents the poorly developed turbulent boundary layer; hence, the effective SWBLI control is difficult to be ensured.