Comprehensive study of vortices interaction and blades height effect in a Darrieus vertical axis wind turbine with J‐type blades

• Published in: Energy science & engineering Vol. 12; no. 10; pp. 4371 - 4393
• Main Authors: Farzadi, Ramin, Gharapetian, Derrick, Bazargan, Majid
• Format: Journal Article
• Language: English
• Published: London John Wiley & Sons, Inc 01.10.2024; Wiley
• Subjects: Alternative energy; Axes of rotation; Axis movements; Blades; Commercialization; Demand analysis; dynamic stall; Fluid flow; J‐type blade; Numerical analysis; Performance enhancement; Ratios; Reynolds number; self‐starting; Simulation; Tip speed; tip vortices; Torque; Turbines; Urban areas; vertical axis wind turbine; Vertical axis wind turbines; Vortices; Wind effects; Wind power; Wind speed
• ISSN: 2050-0505; 2050-0505
• DOI: 10.1002/ese3.1892

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. ‎ 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 model the rotational motion of blades more accurately 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.