Computational Effects of Winglet Tilted Within Range of -45° and +45° on the Up-Scale Wind Turbine Blade Using CFD

The effects associated with the tilted blade tip section on power production and bending load are presented in this study.The blade tip's section of 0.045R size was inclined to the pressure and suction sides for cant angles within a range of -45° to +45° .National Renewable Energy Laboratory (NREL) 5MW wind turbine blade was used as a reference blade.The numerical computations were performed using the finite volume method through ANSYS Fluent version 19.1.First, the aerodynamic performance of different configurations was examined based on computation results of axial force, aerodynamic torque and bending load on flap-wise direction.The best performing blade configuration was selected for further investigations on pitch angle sensitivity for varying wind speed between rated wind speed and cut-out wind speed.A steady-state pressure based solver utilizing Semi-Implicit Method for Pressure Linked Equations (SIMPLE) algorithm was used to solve Reynolds Average Navier-Stoke (RANS) equations closed with Shear Stress Transport (SST) turbulence model.All blades with winglets increase aerodynamic torque.The winglets inclined to the suction side result in a higher increase of aerodynamic torque than the corresponding winglets tilted to the pressure side.The winglet tilted by a cant angle of 15° produced the highest aerodynamic torque increment by about 10% as compared to other blades with winglets.A similar performance trend was observed for the blade with and without winglet when the pitch angle was varied according to the specified wind speed.The general conclusion was made that a winglet can be used to enhance power extraction without the necessity to increase the rotor diameter.