Aerodynamic Performance of Trailing-Edge Modification of H-Type VAWT Blade Considering Camber Effect

Abstract

This paper investigates the flow characteristics and wind energy utilizations of H-type vertical axis wind turbine (VAWT) blade and its trailing-edge modification while having a certain camber to facilitate a greater understanding of the effects of airfoil’s trailing-edge thickness and relative camber. The geometric dimensions are designed for 100 W wind wheel with NACA0021 airfoil, whose trailing-edge thickness is 0.442%c (with c the chord length), and the simulation accuracy of the Computational Fluid Dynamics (CFD) approach is validated through comparing the calculated results of the Realizable k–e turbulence model with experimental data. The blunt trailing-edge optimization of NACA0021 airfoil is performed by taking the maximum lift-drag ratio as the optimization objective, but the wind energy utilization of wind wheel with the optimized airfoil decreases with the increase of the trailing-edge thickness. Thus, the airfoil NACA0021 is modified to a sharp trailing-edge airfoil, namely, NACA0021S, and the wind energy utilization increases slightly. The airfoil’s relative camber is then increased by making the middle arc line locate on the circumference of wind wheel, and the effects of the relative camber on the pressure and vorticity distribution, torque, and wind energy utilization are analyzed. The results indicate that after the relative camber increases, the positive and negative pressure region areas decrease for NACA0021 and NACA0021S airfoils, and so do the length and distribution of the wake, but the torque coefficient and wind energy utilization increase.