Parametric Study Of Winglets On The Aerodynamic Performance Of H-type Vertical Axis Wind Turbines

The low power efficiency of vertical axis wind turbine(VAWT)hinders its potential full deployment.Given that winglets improve the overall efficiency of an aircraft in the field of aerospace,their use on the blades of VAWTs poses as a possible solution for better aerodynamic performance.While studying the effects of winglets would be quite beneficial,detailed analyses of the effect of specific parameters used to define winglets for VAWTs are not readily available in the literature.Moreover,the winglet models employed in most studies for H-type VAWTs have a sharp physical connection between the winglet and the blade.Such an abrupt connection would produce interference drag in airplane wings,and such interference is likely to deteriorate the effectiveness of VAWT blades as well.The present work examines the effect of curvature radius of winglet on such interference on the aerodynamic properties of an H-type VAWT.Furthermore,the present study also includes a detailed examination of the effects of cant angle of winglet and employs a novel value of the cant angle,based on the Whitcomb design.Among the six main parameters used to define a traditional winglet,the present work examines the effect of two specific parameters–cant angle and curvature radius.The Computational Fluid Dynamics(CFD)initial configuration of the Htype VAWT without any change on the blade is validated by comparison with experimental data from the available literature.The present work compares the effect of the cant angle and curvature radius of the winglet on the turbine performance of a VAWT.Maximum the turbine performance and aerodynamic forces were observed for winglet model with the novel cant angle 75° and least curvature radius of 12.5% of winglet height.The results show a clear relationship between the parameters studied and the subsequent aerodynamic performance of the turbine.Specifically,the performance improves by up to 10.93% with a winglet employing a cant angle of 75° and a curvature radius of 12.5%compared to the base model.The winglet assists in maintaining the pressure between the two sides of the blades,thus weakening the tip vortex and improving the aerodynamic efficiency of the surface near the tip of the blade.Furthermore,the study also shows the effect of these chosen parameters on tip vortices and flow fields around the entire blade and the turbine structure.Winglets are effective devices to enhance the performance of a VAWT rotor at a specified velocity and hence,can be widely applicable for energy extraction especially in areas with site restrictions.