Active skin friction drag reduction using different schemes

Abstract

This work explores experimentally the active control techniques for skin friction drag reduction in a turbulent boundary layer based on wall perturbation generated by piezo-ceramic actuators. Three different schemes, i.e., the open-loop, feed-forward, and combined feed-forward and feedback controls are investigated, achieving the maximum drag reductions of 30, 24 and 29 %, respectively. The corresponding duty cycles are 100, 50, and 60 %, respectively, suggesting a good potential to cut down substantially the input energy under the closed loop control strategy. The flow physics behind is also discussed.