Numerical investigation on the helix angle to smoothen aerodynamic torque output of the 3-PB Darrieus vertical axis wind turbine

• Published in: Journal of wind engineering and industrial aerodynamics 2023-03, Vol.234, p.105323, Article 105323
• Main Authors: Moradi Ghareghani, Mohammad Sadegh, Abdolahifar, Abolfazl, Karimian, S.M.H.
• Format: Article
• Language: English
• Subjects: 3-PB turbine; Darrieus VAWT; Helical blade; Helix angle; Torque fluctuation; Vertical axis wind turbine
• ISSN: 0167-6105; 1872-8197
• DOI: 10.1016/j.jweia.2023.105323

This research aims to smoothen the output torque of the three-part-blade (3-PB) Vertical Axis Wind Turbine (VAWT) by setting a proper helix angle while maintaining its average of torque output. Aerodynamic performance of the turbine with different helix angles between 60° and 120° and their corresponding flow structures are precisely studied at wind speed of 7 m/s and Tip Speed Ratios (TSRs) from 0.44 to 1.77 using three-dimensional numerical simulation. Results show that the best performance occurs with helix angle of 80°. A significant reduction in the deviation of turbine torque coefficient from its average is seen with almost no change in turbine's average torque coefficient. Having compared the aerodynamic performance of the proposed turbine with that of the base 3-PB VAWT with 60° helix angle, 40% and 80.64% reductions in the deviation of turbine torque coefficient from its average value are observed at low TSR of 0.44 and high TSR of 1.77, respectively. Based on these results, it is strongly recommended to use 3-PB turbine with the optimal helix angle when structural problems caused by torque fluctuations such as fatigue stress are crucial. More insight into the flow structure is provided by comparing 3-PB turbine with a helical-blade turbine. •Different helix angles are implemented on a three-part-blade Darrieus VAWT.•3D numerical simulations are conducted in flow condition at TSRs from 0.44 to 1.77.•Helix angles between 60° and 120° are studied to reduce torque fluctuations.•A significant reduction up to 80.64% in output torque fluctuations are observed.•The turbine reduces torque fluctuations while maintaining its average output torque.