NREL Phase VI wind turbine blade tip with S809 airfoil profile winglet design and performance analysis using computational fluid dynamics

A crucial factor in designing the wind turbine blade tips for improved aerodynamic performance is the winglet geometry. The potentials of curved planform winglet profiles for performance augmentation have not been adequately investigated. This study focuses on modifying the NREL Phase VI blade tip geometry with different winglet configurations using the S809 airfoil profile. The benchmark blade and the blade with a winglet were designed and simulated using CFD. Accordingly, three distinct winglet designs were created to characterize the flow behavior at the tip and tip vortices. For methodology design and validation, the NREL Phase VI blade served as the benchmark blade. Consequently, the CFD and QBlade simulation and numerical findings are compared with data from the NREL Phase VI experiment. When comparing the simulated parameters like power and pressure coefficients with measurements, there is an adequately high degree of agreement. Therefore, compared to the benchmark blade, the aerodynamic power shows a 5.34% to 9.97% gain, while the increase in axial thrust force shows 5% to 11.84% for the wind speed between 5 m/s and 13 m/s. Moreover, all the winglets show a comparable power boost at low wind speeds, while the blade with winglet (W2) marginally shows better aerodynamic performance at higher speeds. Furthermore, axial thrust force rises as the winglet curvature length increases, thereby winglet W3 shows a substantial axial thrust force rise. The results further demonstrate that the geometry of blade tip winglets can have a considerable impact on the wind turbine blade effectiveness as a whole.