Time-resolved CFD analysis of torque generation in an L-shaped vertical-axis wind turbine
Baizhuma Z. Kalassov N. Manatbayev R. Isataev M. Seydulla Z. Georgiev A.
1 February 2026Elsevier Ltd
Energy
2026#344
Vertical-axis wind turbines (VAWTs) are often limited by low power coefficients and pronounced cyclic torque fluctuations. In this study, a four-bladed L-shaped vertical-axis wind turbine is numerically investigated to clarify the influence of the arm-length ratio on torque generation and aerodynamic performance. Time-resolved two-dimensional URANS simulations using the SST k–ω turbulence model are performed for arm-length ratios from 0.50 to 1.00 over a tip speed ratio (TSR) range of 2.5–4.5. Phase-resolved blade-wise moment coefficients are evaluated and combined to obtain rotor-level torque and power coefficients. The results indicate that the symmetric configuration (arm-length ratio = 1.0) delivers the highest average torque and power output at moderate operating conditions, with peak performance at TSR = 3–3.5 and power coefficient improvements of up to 15–20 % compared to shorter-arm configurations. At higher TSRs, performance differences diminish, while shorter arms enhance secondary torque peaks and alter the phase distribution of cyclic loads. Phase-locked pressure and vorticity analyses reveal the underlying flow mechanisms governing these trends. The findings provide practical guidance for the aerodynamic design of L-shaped and multi-rotor VAWT systems.
Asymmetric rotor , Design optimization , L-shape VAWT , Numerical simulations , Vertical axis wind turbine
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Department of Thermal and Technical Physics, Al-Farabi Kazakh National University, Almaty, Kazakhstan
Institute for Innovation and Smart Technologies University of Telecommunications and Posts, 1 Akad. Stefan Mladenov str., Sofia, 1700, Bulgaria
Department of Thermal and Technical Physics
Institute for Innovation and Smart Technologies University of Telecommunications and Posts
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