Steady and Unsteady Plasma Wall Jets for Separation and Circulation Control

Abstract

An experimental investigation of separation and circulation control was carried out using corona discharge as well as dielectric barrier discharge actuators at typical micro air vehicle (MAV) Reynolds numbers. All actuators were calibrated by direct measurement and their limitations were assessed on the basis of conventional low Reynolds number active flow control data. Aerodynamic data from corona discharge and high frequency dielectric barrier discharge actuators highlighted their applicability at MAV-type Reynolds numbers. Modulating the dielectric barrier discharge actuators at frequencies corresponding to reduced frequencies of O(1), resulted in significant improvements to Cl,max, which increased with decreasing Re. At the low end of the MAV Reynolds number range (Re~20,000) modulation increased Cl,max by more than a factor of 2 and typical low Re hysteresis was eliminated. Of particular interest from an applications perspective was that performance, measured here by Cl,max, was shown to increase with decreasing duty cycle, and hence power input. In fact, duty cycles of around 0.66% were sufficient for effective separation control, corresponding to power inputs on the order of 1.2 milliwatts per centimeter.