Characteristics of drag-reduced turbulent boundary layers with pulsed-direct-current plasma actuation

Experiments were performed using an active flow control approach that has shown the ability to significantly reduce the viscous drag in turbulent boundary layers. The purpose of this work was to document the changes in the turbulence characteristics of the boundary layer with the drag reduction. The flow control involved generating a steady spanwise velocity component of the order of vortical structures, indicate a suppression of coherent features in the wall layer. These results are consistent with an underlying mechanism for drag reduction that comes from a suppression of the turbulence producing events in the wall layer associated with the wall streak structure.