Design and characterization of a virtual-dimple plasma actuator for turbulent skin-friction drag reduction

A virtual-dimple plasma actuator (VDPA), capable of producing suction flow above a staggered array of circular anodes, is proposed for turbulent skin-friction drag reduction. Characteristics of the VDPA at different discharge voltages are studied using multi-slice stereoscopic particle image velocimetry and electrical measurements. Results indicate that the VDPA induces a downwash suction flow above the cathode, a wall-normal jet flow above the anode, and a counter-rotating vortex pair caused by near-wall jet impingement. With increasing discharge voltage, both the peak blowing velocity and centerline-jet decay rate increase, while the dimensionless total circulation decreases linearly. For different cases, the vortex-core spacing remains approximately unchanged at 0.43D.