Numerical investigation on the spanwise chord distribution effects on the performance of an H-darrieus vertical axis wind turbines

Abstract

The efficiency of Darrieus wind turbines has increased significantly due to developments in blade design, albeit at the expense of the simplicity provided by simple straight blades. The purpose of this research is to gain insight into the influence of various curvatures embedded in the plan of the blade while maintaining its simple straight shape. A variation in chord length along the span defines the curvature. To assess their effect on performance and efficiency, concave, and convex Leading-Trailing Edged Blades (LTEB) are investigated and evaluated in comparison to straight blades. That is viable to gain valuable insight about these blade designs' potential advantages in various applications by studying their aerodynamic characteristics and flow characteristics. The Q-blade tool is used to simulate 3D unsteady Nonlinear Lifting Lines Free Vortex Wake (3D-NLLFVW). The virtual camber effect brought on by flow curvatures is implemented to improve the results' accuracy. According to the findings, H-Darrieus' aerodynamic efficiency climbed by 16% and 9.5% at high TSR. For the concave and convex LTEBs, the torque ripple is smoothed by 37% and 19%, respectively. Additionally, compared to the straight-bladed rotor, the chosen variations enable volume reductions of 53% and 28%.