Bi-objective optimization of scaled wind turbine blades based on thrust-power coefficient for wind tunnel test

Wind tunnel tests are crucial for studying wind turbine wake effects, but the Reynolds effect causes discrepancies in power and thrust coefficients between scaled models and full-scale turbines, impacting wake simulation accuracy. This paper proposes a bi-objective optimization design method of the scaled blade based on the thrust-power coefficient. Using a pattern search algorithm, the method optimizes both coefficients by adjusting optimization objectives. Results show that chord length distribution primarily affects the thrust coefficient when airfoil type is fixed, while twist angle significantly influences the power coefficient. The chord length and twist angle are then considered as optimization variables to design a scaled blade. After optimization, the thrust coefficient is consistent with the prototype turbine, while the power coefficient reaches 0.2, which could be used in the 5MW wind turbine test. Furthermore, the effects of chord length and twist angle on the thrust and power coefficients of the wind turbine blade were examined using a 5MW wind turbine as an example, respectively. In this examination, numerical simulation is employed to verify the aerodynamic parameters of the optimized blade with thrust-power coefficient, thereby demonstrating the reliability of bi-objective optimization method.