Visualization of aerodynamic forces and flow field on a straight-bladed vertical axis wind turbine by wind tunnel experiments and panel method

Highlights: • Aerodynamic performance of a straight-bladed vertical axis wind turbine is studied by multiport pressure measurement device. • Vortex characteristic of straight-bladed vertical axis wind turbine is discussed by panel method. • Radial force coefficients decrease with the increase of the blade spanwise. • The rotor blade flows out the positive horizontal vortex at θ = 45° and negative horizontal vortex at θ = 200°. • The circulation amount contour of the vertical vortex becomes narrower when closer to the blade tip. This paper investigated the evaluation of the aerodynamic performance and vortex characteristic of a straight-bladed Vertical Axis Wind Turbine (VAWT) in the spanwise direction. To observe the aerodynamic forces characteristics, pressures acting on the blade surface were measured by a multiport pressure measurement device. Pressure measurement was carried out in the spanwise sections of z/(H/2) = 0, 0.4, 0.70, 0.8 and 0.90 with wind tunnel experiments. Meanwhile, panel method based on the lifting surface theory was used to study the flow characteristics of VAWT. As a result, it was clarified that the absolute value of radial force coefficient from measurement took the maximum value at the upstream region around the azimuth angle of 100° and became small at the downstream region. Moreover, the radial force coefficient of the experimental value was significantly affected by the three-dimensional and decreased as it approached the blade tip. For the flow field, the circulation amount contour of the vertical vortex was wider near the blade center and became narrower around the blade tip in the blade spanwise direction. This study provided a better understanding of the development of aerodynamic forces and vortex characteristic through pressure measurements and panel method calculations.