Effect of Winglet Blade on the Performance of Small-Scale Horizontal Axis Wind Turbine

Abstract

Abstract Wind energy as a promising energy solution has drawn the attention of many researchers to enhance its generation efficiency. Understanding the aerodynamics of the new designs and configurations of airfoils is crucial in predicting the aerodynamic behavior of wind turbine rotors. Improving the aerodynamic performance of airfoils participates to a far extent in improving a turbine’s performance, hence increasing a turbine’s power output. Studying aerodynamic performance for both airfoils and wind turbines can be done either by wind tunnel testing, Computational Fluid Dynamics (CFD) techniques, or both. In this work, the effect of winglet direction and cant angle on the power production of a small-scale Horizontal Axis Wind Turbine (HAWT) was investigated numerically using CFD techniques after measuring the experimental Tip Speed Ratio (TSR) experimentally in the University of Wisconsin Milwaukee Wind Tunnel Facility. Suction side and pressure side winglets were studied over a wide range of cant angles between −90 degrees and +90 degrees using three wind speeds 5, 10, and 15 m/s. Blade Element Momentum (BEM) theory was used to design the optimum twisted blade as a baseline design. The output power was the key parameter in this study, where each design power output was compared to the baseline design without winglets. All winglet design parameters other than the cant angle (length, radius of curvature, and toe, twist, and sweep angles) were fixed throughout this study to isolate their effect. Computational Fluid Dynamics (CFD) methods were used to capture the aerodynamic performance for the most promising configuration. It was found that all the upstream and downstream wingletted turbines outperformed the baseline design except for the perpendicular downstream (−90°) winglet at low wind speed. Furthermore, it was found that the enhancement is more pronounced with higher velocities.