Conditioning Turbulent Channel Flows With Wall Plasma Jets

In this study, a fully developed turbulent channel flow is conditioned by an array of wall-mounted plasma actuators built to inject crosswise oscillating jets aiming at a control effect resembling the one caused with crosswise oscillations of the flow-exposed surfaces. Several oscillation frequencies were tested as well different duty cycles. Both these parameters can remarkably modify the flow forcing caused by the considered array of plasma actuators. The controlled flow was inspected with high-resolution PIV at two different wall normal planes, one near the wall and one within the log-layer. Statistical and instantaneous velocity-educed fields are discussed together with the statistical features of the low speed streaks. These are the velocity field footprint of drag-increasing flow structures typical of turbulent wall-bounded flows and, as such, their characteristics are interesting for friction drag reduction efforts.