Winglet optimization for a model-scale wind turbine

A winglet optimization method is developed and tested for a model-scale wind turbine. The best-performing winglet shape is obtained by constructing a Kriging surrogate model, which is refined using an infill criterion based on expected improvement. The turbine performance is simulated by solving the incompressible Navier-Stokes equations, and the turbulent flow is predicted using the Spalart-Allmaras turbulence model. To validate the simulated performance, experiments are performed in the Norwegian University of Science and Technology wind tunnel. According to the simulations, the optimized winglet increases the turbine power and thrust by 7.8% and 6.3%, respectively. The wind tunnel experiments show that the turbine power increases by 8.9%, while the thrust increases by 7.4%. When introducing more turbulence in the wind tunnel to reduce laminar separation, the turbine power and thrust due to the winglet increases by 10.3% and 14.9%, respectively.

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