Generation of Plasma Induced Flow Actuation by DC Glow-like Discharge in a Supersonic Flow

Plasma induced flow field modification is studied experimentally using non-equilibrium DC surface discharge in a Mach 3 supersonic flow. An array of small pin electrodes (φ = 3/32”) is used in streamwise plasma discharge configuration. The schlieren imaging shows that an oblique shock can be obtained with a volumetric glow discharge on the cathode with a relatively low current (as low as 50 mA). The actuation is found to be immediate with a time scale less than 222 μs whenever there is a noticeable volumetric glow region on the cathode in both cathode upstream and cathode downstream cases. With a laser schlieren, three identifiable modes are observed and the selected modes which have a volumetric glow on top of the cathode can give an actuation while the other mode does not show any noticeable effect. The conditions to get an appropriate mode are dependent mostly on the stagnation pressure. Increasing the current gives a preference to have a constricted plasma while a pressure decrease gives a volumetric glow.