Aerodynamic optimization was performed for the DU21 airfoil of the NREL 5MW wind turbine = to enhance its lift-to-drag characteristics. An optimization framework based on a dynamic adaptive genetic algorithm was developed, utilizing seventh-order Bézier curves for geometric parameterization of the airfoil. Aerodynamic performance was evaluated by using the XFOIL solver. The objective function was defined to maximize the lift-to-drag ratio. Validation is performed using Computational Fluid Dynamics (CFD) based on the SST k-ω model incorporating the γ-Reθ transition correction. The results indicate that the optimized airfoil achieved an 8.93% increase in lift-to-drag ratio at 7° angle of attack, characterized by an enhanced leading-edge suction peak and improved pressure distribution. CFD results confirmed that the optimized design significantly delayed flow separation within an angle of attach range of 5 to 12°, with discrepancies between computational and experimental lift coefficients remaining below 8% at lower attack angles. These findings demonstrate that the proposed optimization strategy significantly enhances airfoil aerodynamic performance, offering an effective methodology for wind turbine blade design.
Yuan et al. (Sun,) studied this question.