NUMERICAL INVESTIGATION OF SEPARATION CONTROL FOR WIND TURBINE AIRFOIL

We simulated the flow over the NREL S822 wind turbine airfoil for a chord Reynolds number of 100,000 and an angle of attack of 5deg These conditions approximately match the blade element conditions at 80% radius of a 2m turbine that is operating at 300rpm. A simulation of the uncontrolled flow with steady approach flow conditions shows flow separation on the suction side which is consistent with University of Illinois at Urbana-Champaign experimental data. We also investigated the effect of a time-dependent approach flow similar to the conditions encountered during yawed turbine operation Because the blade rotation frequency is much lower than the frequencies associated with the blade aerodynamics we increased the frequency of the approach flow fluctuations Nevertheless, the time-dependent inflow was found to have little effect on the separated flow Finally, we investigated separation control using a plasma actuator located near the maximum thickness on the suction side of the airfoil. Pulsed actuation was found to be very efficient and effective as the disturbance input is amplified by the flow.