Aerodynamic optimization of wind turbine airfoils using response surface techniques

An improved aerodynamic optimization technique for two-dimensional wind turbine airfoils is presented in this article. On the basis of the combination of response surface method and uniform experimental design, a space filling design of experiment, this technique optimizes the lift-to-drag ratio of an airfoil at the design angle of attack. In order to reduce the number of design variables, the upper and lower surfaces of a reference airfoil are, respectively, fitted by using two B-spline curves with only four control points each. By using the ordinates of the eight control points as design variables, the ranges of the design variables are set and the airfoil is parameterized. Then, according to the uniform design tables, the values of each design variable at different levels are determined and various airfoil shapes are generated by using the specified combinations of the design variables. Finally, the optimal ordinates of the eight control points are obtained using a quadratic polynomial expression that is the regression of the computational results of flows around the airfoils. The computational results of flows around the optimized shapes of four airfoils reveal that the proposed technique, compared with some other optimization methods in the literature, is a time-saving and effective method to seek better aerodynamic performance for wind turbine airfoils.