Turbulent drag reduction using pulsed-DC plasma actuation

In this paper, surface-mounted arrays of pulsed-DC dielectric barrier discharge plasma actuators are used to achieve skin friction drag reduction in turbulent boundary layers. The arrays are designed to produce a near-wall plasma-induced spanwise flow for the purpose of preventing the lift-up of low-speed streaks. Two array designs are demonstrated. One produces a unidirectional spanwise flow and the other a series of opposed wall jets. Both configurations are shown to produce unprecedented levels of drag reduction in excess of 70%. The amount of drag reduction achieved is shown to scale on the number of viscous wall units between adjacent surface electrodes which effectively sets the number of low-speed streaks under simultaneous control. In particular, the level of drag reduction increases logarithmically as the number of streaks under simultaneous control decreases. Furthermore, due to the low-power input required by the pulsed-DC actuator, this level of drag reduction is achieved with net power savings.