Numerical investigation of the power performance of the vertical-axis wind turbine with endplates

Abstract

An H-rotor vertical axis wind turbine (VAWTs) can operate independently in any wind direction, making it aerodynamically efficient and suitable to harness wind energy in low wind speed areas. The aerodynamic efficiency of VAWTs is highly dependent on the blade geometry, especially the blade tip. Tip vortices produced at the blade tips can negatively affect the VAWT’s aerodynamic efficiency. Adding endplates to the blade tips can minimize the effects of tip vortices on VAWTs. In this paper, several endplate designs are used to evaluate the effectiveness in improving the power coefficient, Cp of a VAWT at three different tip speed ratios (TSRs) using three-dimensional computational fluid dynamics (3D CFD) simulation. The power coefficients of VAWTs with endplates are compared with the baseline model with the same geometrical parameters where the baseline VAWT model is based on the experimental model from the literature. Since the focus of this study is on the blade tip design, a simplified 3D VAWT model is used where the supporting shaft and arms of the VAWT are excluded to reduce the needed computational capacity. Among the various endplate designs used in this study, the semi-circular inward endplate (ED3) with a diameter equivalent to 1.2 blade chord length showed the best improvement in the Cp which is by 7.45%, and 5.79% for at the TSRs of 2.19 and 2.58, respectively. The pressure difference on both sides of the blade was also examined. The results revealed that the endplate can prevent the flow from bypassing the blade tip, hence, preventing the occurrence of tip vortices while improving the aerodynamic efficiency near the blade tip, ultimately, improving the overall Cp of a VAWT.