Wind Tunnel Experiments and Numerical Study on Performance Characteristics of an H-type Vertical Axis Wind Turbine in the Spanwise Direction

Abstract

The aerodynamic forces and vortex characteristics of an H-type Vertical Axis Wind Turbine (VAWT) become complicated because of dynamic stall, particularly in the three-dimensional impact on the blade spanwise direction. This study focused on the evaluation of the aerodynamic performance and vortex characteristics of an H-type VAWT in the spanwise direction by numerical simulations and wind tunnel experiments. Pressure acting on the blade surface was obtained from multiport pressure measurement devices by wind tunnel. Meanwhile, the vortex field around different blade sections was investigated through numerical simulations. The stall behavior was analysed by comparing the results of numerical simulations and experiments. As a result, the tangential force of single blade was mainly contributed at the chordwise position of x/c≤0.4c and the power of single blade was mainly contributed at the azimuthal angle range of 60°≤θ≤150° in the blade section position region of 0≤z/(H/2)≤0.7. At the section position of z/(H/2)=0.5, the initial flow separation was found at the suction side and progressed forward to the leading edge. With the increase of the tip speed ratios, the decreasing position of the averaged local power coefficient of each section was closer to the middle section of z/(H/2)=0, and the attenuation speed became faster. The power coefficient reductions at the blade section position of z/(H/2)=0.9 were 38.29%, 46.78% and 56.42% when the tip speed ratios were 1.38, 2.19 and 2.58, respectively. The results of this study provided a better understanding of the development of the performance characteristics and vortex characteristics of H-type VAWT.