Numerical investigation of winglet effects on power performance and wake dynamics in horizontal axis wind turbines

Abstract

This study investigates how winglet geometry influences wake dynamics and associated pressure fluctuations in horizontal-axis wind turbines and how these effects translate into changes in power production and wake recovery. Two winglet designs are evaluated relative to a baseline turbine using Unsteady Reynolds-Averaged Navier–Stokes simulations with the SST k–ω turbulence model. The results show that the optimized winglet slightly increases the near wake velocity deficit while reducing peak turbulence intensity. The extended winglet lowers the streamwise averaged velocity deficit to a distance of 1D, where D is the turbine diameter, and maintains turbulence levels close to the baseline. For both winglet geometries, differences in velocity deficit and turbulence intensity become negligible beyond x/D≈8. Winglets also promote faster decay of tip vortex rings, reducing wake vorticity and weakening coherent structures. Mean kinetic energy flux profiles indicate that winglets suppress turbulence production in the near wake while enhancing energy transport farther downstream. The optimized and extended winglets increase the power coefficient by 8.97% and 9.43%, respectively, and increase thrust by 14%. Root-mean-square pressure fluctuation (p_rms^′) reveals weaker and smoother tip vortex induced peaks that vanish over shorter streamwise distances. These results demonstrate that blade tip modifications based on winglets improve aerodynamic efficiency while reducing vortex induced instability, supporting improved downstream energy availability and wind farm power yield.