Aerodynamic Performance Enhancement of Wind Turbine by Shape Optimization at Low Reynolds Numbers

In the present research, E387, RG15, BW-3, SD6060, and S2055 airfoils are selected because, with the increase of Reynolds number (Re), the five mentioned airfoils' peak lift-to-drag ratio (C_L⁄C_D ) decreases. By reducing the peak C_L⁄C_D of airfoils, the aerodynamic performance of wind turbines (WTs) decreases. At first, the peak C_L⁄C_D of five selected airfoils between Re from 6 〖 10〗^5 to 10^6 are investigated in XFOIL. A comparison between E387, BW-3, SD6060, S2055, and RG15 airfoils at Re of 6  10^5 to 10^6 showed that the highest maximum C_L⁄C_D for the E387 airfoil at Re of 9  10^5 at the angle of attack (AoA) of 3º is 116.70. Also, the lowest maximum C_L⁄C_D value for the BW-3 airfoil at a Re of 8  10^5 at an AoA = 3º is 83.70. Plus, the current study compared and validated with the experimental data. Moreover, the result illustrated that with the increment in Re, the peak value of the maximum C_L⁄C_(D ) has decreased for the entire airfoils. Then, to enhance the aerodynamic characteristics of the five aforementioned airfoils, their shapes were modified. The results revealed that the maximum C_L⁄C_D for the modified RG15, E387, BW-3, SD6060, and S2055 airfoils in the Re of 〖 10〗^5 to〖 10〗^6 and with an increase of Re is 〖 10〗^5. As well as, the lowest and highest C_L⁄C_D of all modified airfoils occurred at a Re of 〖 10〗^5 and 〖 10〗^6. Moreover, the E387 airfoil has the highest maximum C_L⁄C_D for all modified airfoils at Re of 〖 10〗^6 is 142.96 at an AoA of 5º.