Numerical investigation of flow control using plasma actuator to improve aerodynamic characteristics of a pitching airfoil

In this study, DBD plasma actuators’ effect on the flow over a pitching NACA 0012 airfoil is investigated. Flow is considered two-dimensional, incompressible, and turbulent at a Reynolds number of 135,000, which is equivalent to the flow around wind turbine blades. Airfoil is oscillating beyond static stall angle and experiences deep dynamic stall. The plasma actuator effect is added to momentum equations as a body force using a phenomenological model. It is observed that the plasma actuator increases mean lift, decreases mean drag, reduces lift coefficient hysteresis, and delays separation. The effect of the plasma actuator on the pitching moment coefficient hysteresis and negative aerodynamic damping coefficient is also investigated. Then the effect of actuator location over the suction side of the airfoil on aerodynamic performance is studied and leading-edge is selected as the optimal location. In addition, applied voltage and actuation frequency are varied and their effects on aerodynamic coefficients and negative damping coefficient are investigated. Furthermore, it is observed that the actuator with a 50% duty cycle with lower electric power consumption has almost the same results compared to continuous actuation. Finally, the free stream oscillation effect on aerodynamic coefficients and plasma actuator performance is discussed. It is observed that in the case of oscillatory free stream, the plasma actuator causes an increment in maximum lift coefficient and little delay in the dynamic stall while increasing the mean drag coefficient and lift coefficient hysteresis area. To examine the accuracy of the results, aerodynamic coefficients of oscillating airfoil without flow control are validated against numerical and experimental data.