Gradient-Based optimizations with CFD techniques and adjoint approach for wind turbine airfoils

• Optimization of wind turbine airfoils, taking into account local flow conditions and varying angles of attack • Airfoil efficiency improvement due to the optimization process depends on local flow conditions • Increased efficiency of 13.63% for Porto Alegre and 15.96% for Salvador, taking into account local flow conditions. • Changing the angle of attack, the efficiency improvement ranged from 6.5% to 8.5% • The maximum performance for the optimized airfoil occurred at AoA of 7° The global reliance on fossil fuels has resulted in significant environmental challenges. In this scenario, low-carbon alternatives, such as wind power, stand out as clean, renewable energy sources that promise to mitigate these issues. Previous efforts have aimed to improve wind power extraction by designing more efficient wind turbine airfoils. Although some investigations have considered local flow conditions during the design process, this aspect remains insufficiently explored. The primary objective of this study is to design wind turbine airfoils that account for local flow conditions and varying angle of attack. A gradient-based optimization method, coupled with the adjoint approach, was employed for aerodynamic analysis of airfoils. Computational Fluid Dynamics (CFD) simulations were used to perform aerodynamic analyses of the NACA 0012 airfoil as a baseline configuration at five locations in Brazil. The optimization resulted in improvements in aerodynamic efficiency ranging from 13.63% to 15.96%. The results show that variations in the airfoil’s angle of attack significantly affect the optimization outcomes. In contrast, local flow conditions have a comparatively minor effect within the range of parameters considered.