Effect of blade aspect ratio on the performance of a pair of vertical axis wind turbines

Abstract

The effect of blade aspect ratio on the power generation of a pair of straight-bladed vertical axis wind turbines was studies using computational fluid dynamics simulations. Sixteen numerical experiments were performed, and coefficients of power of isolated and paired wind turbines were evaluated at four different blade aspect ratios, including 4, 6, 8, and 10 at solidities of 0.25 and 0.45. It was realized that at each solidity, coefficients of power of isolated and paired wind turbines increased by increasing the blade aspect ratio. At the solidity of 0.25, the power improvement of paired wind turbines compared to an isolated wind turbine increased from 2% at the aspect ratio of 4 to 5% at the aspect ratio of 10. While at the solidity of 0.45, the power increment of paired wind turbines compared to an isolated wind turbine was 18.5% at the aspect ratio of 4 and 23.5% at the aspect ratio of 10. Investigating the velocity contour plots revealed that the rate of wake recovery behind wind turbines decreased by increasing the blade aspect ratio.