Airfoil Shape Optimization of a Horizontal Axis Wind Turbine Blade using a Discrete Adjoint Solver

In this study, airfoil shape optimization of a wind turbine blade is performed using the ANSYS Fluent Adjoint Solver. The aim of this optimization process is to increase the wind turbine output power, and the objective function is to maximize the airfoil lift to drag ratio (Cl/CD ). This study is applied to the NREL phase VI wind turbine, therefore, the S۸۰۹ airfoil is used as a reference profile. First, for the validation of the applied numerical model, steady-state simulations are carried out for the S۸۰۹ airfoil at various angles of attack. Then, the optimization is performed with the airfoil set at a fixed angle of attack, , considering three Reynolds numbers, Re =۳ ۱۰۵,۴.۸ ۱۰۵  and ۱۰۶. Next, computations are performed for the fluid flow around the optimized airfoils at angles of attack AOA= ۶.۱° ranging from ۰° to ۲۰°. The results show that (i) the lift to drag ratios of the optimized airfoils are significantly improved compared to the baseline S۸۰۹ airfoil, (ii) this improvement is sensitive to the Reynolds number, and (iii) the Cl/CD ratios are also improved for another angle of attack values. Thereafter, the optimized airfoils are used for the design of the NREL Phase VI blade and the aerodynamic performances of this new wind turbine are assessed using the open-source code QBlade. These latter results indicate that when the blades are designed with the optimized airfoils, the wind turbine aerodynamic performances increase significantly. Indeed, at a wind speed of ۱۰ m/s, the power output of the wind turbine is improved by about ۳۸% compared to that of the original turbine.

Keywords:

CFD , Airfoil , Wind turbine blade , Aerodynamic performance , Adjoint solver , Shape optimization