Airfoil optimization for wind turbine application

An airfoil optimization method for wind turbine applications that controls the loss in performance due to leading edge contamination is developed and tested. The method uses the class-shape-transformation technique to parametrize the airfoil geometry and uses an adjusted version of the panel code XFOIL to calculate the aerodynamic performance. To find optimal airfoil shapes, the derivative-free Covariance Matrix Adaptation Evolution Strategy is used in combination with an adaptive penalty function. The method is tested for the design of airfoils for the outer part of a megawatt-class wind turbine rotor blade, and the results are compared with airfoils from Delft University. It is found that the method is able to automatically create airfoils with equal or improved performance compared with the Delft designs. For the tested application, the adjustments performed to the XFOIL code improve the maximum lift, post stall, and the overall drag predictions.