Active circulation control on the blunt trailing edge wind turbine airfoil

Active circulation control on a thick blunt trailing edge wind turbine airfoil is proposed and numerically investigated by solving Reynolds-averaged Navier-Stokes equations along with Spalart-Allmaras one-equation turbulence model. The code is validated by comparing results with experiment based on the grid independency study. The circulation control greatly enhances the aerodynamic characteristics of the flatback airfoil by increasing the lift and simultaneously reducing the drag while using external energy. The drag can be reduced even to be negative due to combined contributions from the well-controlled wake separation and the jet reaction force. The two typical control regimes, namely, separation control and super-circulation control, are observed and analyzed. The enhancement in lift for both regimes can be further improved by increasing jet momentum coefficient or decreasing slot height, but at cost of higher external energy. Investigation shows that a great amount of net gain of energy can be obtained by implementing circulation control on the blunt trailing edge airfoil, and the circulation control with a relatively large slot height has a better control efficiency. It is demonstrated that the present proposed circulation control method is effective, efficient, and thus promising for the flow control in the blunt trailing edge wind turbine application.