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Abstract There is a growing demand to improve the performance of vertical axis wind turbines to facilitate their commercialization for application in urban areas. This study utilizes a 3D numerical analysis to examine the influence of different vortices generated on turbine efficiency with straight and J‐type blades. The numerical simulation of this study employs the Reynolds‐Averaged Navier–Stokes equations and sliding mesh techniques to more accurately model the rotational motion of blades about the turbine axis in relation to the wind. Comparing the output torque and the flow field at different span‐wise sections, the J‐type blades achieve better performance at mid‐spans where the effect of stall vortices is dominant. Conversely, the lower performance of J‐type blades is seen at tip spans due to stronger tip vortices. Investigations also reveal the criticality of the downwind region on the overall performance at high tip speed ratios. It is observed that by increasing the height, the tip vortices are limited to the tip sections, and stall vortices expand further along the blade. At TSR = 1, the improvement by J‐type blades rises from 10% at a height of 0.8 m to 44% at 3 m. The growth in height at lower wind speeds becomes more beneficial. Compared to the straight blades, the self‐starting generated torque by J‐type blades for heights of 0.8, 1.2, and 1.6 m, are improved by 15.6%, 26.9%, and 34.7%, respectively. Overall, it is concluded that by increasing the blade height, the superiority of the J‐type blade becomes more noticeable as the blade mainly contributes to suppressing the stall vortices effect where the tip vortices effect is not presented. |
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