Experimental Study on Suppression of Vortex Shedding Behind a Square Cylinder Using Opposed-Type Plasma Actuators

Vortex shedding in the flow field causes many kinds of problems such as increase of drag and noise. Especially, the von Kármán vortex street behind bluff bodies, e.g. a tire of an airplane and a pantograph of a train, greatly contributes to them. One of the effective methods to suppress the vortices is the use of plasma actuators (PAs). A PA can induce flow by applying a high-voltage and high-frequency AC voltage to its electrodes. In the present study, we use an opposed-type PA (O-PA), which consists of two PAs facing each other. The O-PA can induce a jet in the direction perpendicular to the surface because of a collision of flows induced by the two PAs. In this study, we investigate the control effect of an O-PA on the flow around a square cylinder using an O-PA by means of the PIV measurement. First, we measure the flow induced by an O-PA. It is confirmed that the velocity of the induced flow increases as the applied voltage Vpp increases, and the O-PA induces the jet of about 1.5 m/s under Vpp = 10kV. Next, we measure the flow around a square cylinder with no control. It is confirmed that the von Kármán vortex street occurs behind a square cylinder. Finally, we measure the flow around a square cylinder under the control by the O-PA attached on the rear surface. It is confirmed that the vortex shedding behind a square cylinder is suppressed by the O-PA under Vpp = 10kV.