Turbulent boundary layer drag reduction using pulsed-DC plasma actuation

In this paper, we report on an active flow control approach that has produced unprecedented levels of turbulent boundary layer viscous drag reduction in excess of 70%. Furthermore, by incorporating a flush mounted, pulsed-DC plasma actuator array with exceedingly low power input, the power savings due to drag reduction has exceeded the power input. With regard to turbulence production mechanisms, the actuator gives rise to a reduction in the frequency of near-wall “burst-sweep” events that scales linearly with the wall shear stress. Mean velocity profiles indicate that the effect of the actuation in confined to the sublayer and buffer layer regions and the degree of drag reduction has been shown to scale with the number of low-speed streaks under simultaneous control. Besides the obvious practical interest in this flow control approach, it also offers an opportunity to provide controlled initial conditions with which to investigate the response of the turbulent boundary layer turbulence generation mechanisms.