Capabilities of the dielectric barrier discharge plasma actuator for multi-frequency excitations

Natural instability mechanisms are inherent in most laminar and turbulent flow configurations. Usually, these instabilities result in the formation of flow structures occurring at diverse spatial and time scales. An effective control requires an actuator able to bring momentum transfer over a wide range of frequencies to act on these instabilities. Promising results are expected for such control strategy because, according to stability theory, a small amplitude perturbation can be large enough to produce significant effects even at high Reynolds number. Moreover, simultaneous production of small perturbations at several frequencies can enhance or cancel non-linear interactions; this opens alternative methods for flow control. The focus of this study is to demonstrate the ability of plasma actuators to introduce flow perturbations at single and dual frequencies by simply adjusting the waveform of the voltage applied to the plasma actuator. The flows produced by a dielectric barrier discharge supplied by burst, superposition and ring modulations are described in temporal and frequential domains. The results confirm the potential of non-thermal plasma actuators to produce highly unsteady flows at single, double or multiple frequencies.