Influence of circulation on a rounded-trailing-edge airfoil using plasma actuators

An experimental study on influence of circulation around a symmetric airfoil with a rounded trailing edge is presented. Flow control is achieved by the use of dielectric barrier discharge plasma actuators placed at the trailing edge of the airfoil. Direct lift and drag measurements are taken using an external load balance at freestream velocities of 10, 15 and 20  m/s corresponding to chord Reynolds number of 140,000, 210,000, 280,000. Additionally, time-resolved particle image velocimetry is used in order to elucidate the topology and dynamical response of the wake flow under the influence of actuation. Results indicate an increase in lift coefficient of approximately 0.1 for the lowest tested Reynolds number using the plasma actuator. Flowfield measurements indicate the successful manipulation of the Kutta condition enabled by the plasma actuator. The actuator is enhancing the mixing of the wake near the trailing edge while reducing the dominant shedding frequency. Proper orthogonal decomposition analysis reveals further details regarding the dynamics of the wake flow in presence of actuation, suggesting the sensitivity of the control concept to the positioning of the actuator as well as the angle of attack.