Optimization of an airfoil used in the tip of wind turbine blades for maximizing its lift to drag coefficients ratio

One method to maximize the generated power of wind turbines is to improve the performance of the rotor's blade. This is possible through optimizing their geometry design by maximizing the ratio of the lift to drag coefficients C_l⁄C_d of the airfoils. The airfoils used in the tip section of the rotor blade are thinner compared with other sections of the blade, which makes the tip lighter, thus inducing less amounts of momentum to the turbine hub. In the present study, after examination of 150 airfoils, those that met the criteria for the thickness of the blade tips were chosen. Then, using appropriate aerodynamic analyses, the airfoil featuring the highest value of C_l⁄C_d was selected for further geometrical design optimization. The geometrical design of the selected airfoil was optimized using Xflr software, so that the value of C_l ⁄(C_d )parameter was maximized. For the optimized blade geometry, the maximum increase of about 7.8 % in C_l⁄C_d parameter was noticed compared to that of initial blade.