Turbulent boundary layer control with DBD plasma actuators

The flat-plate turbulent boundary layer at Re_τ =1140 is manipulated using a spanwise array of bidirectional dielectric barrier discharge (DBD) plasma actuators. Based on the features of no moving mechanical parts in the DBD plasma control technology and hot-wire anemometer velocity measurements, a novel convenient method of local drag reduction (DR) measurement is proposed by measuring the single-point velocity within the linear region of the viscous sublayer. We analyze the premise of using the method, and the maximum effective measurement range of −73.1% < DR < 42.2% is obtained according to the experimental environment in this work. The local drag decreases downstream of the center of two adjacent upper electrodes and increases downstream of the upper electrodes. The magnitude of the local DR increases with increasing voltage and decreases as it moves away from the actuators. For the spanwise position in between, the streamwise distribution of the local DR is very dependent on the voltage. The variable-interval time-average detection results reveal that all bursting intensities are reduced compared to the baseline, and the amount of reduction is comparable to the absolute values of the local DR. Compared with previous results, we infer that the control mechanism is that many meandering streaks are combined together into single stabilized streaks.