Modares Mechanical Engineering

Modares Mechanical Engineering

Self-Starting Capability Improvement of Single and Dual Hybrid Darrieus-Savonius VAWTs, Incorporating a Gear Mechanism

Document Type : Original Research

Authors
Sina Hosseini Rad
Morteza Taraghi
Farzad Ghafoorian
Mahdi Moghimi
School of Mechanical Engineering, Iran university of science and technology
10.48311/mme.2025.27795
Abstract
The substantial increase in greenhouse gas emissions has catalyzed the growth of renewable energy sources. In this context, vertical axis wind turbines (VAWTs) have gained significant traction due to their numerous advantages. Notably, Darrieus VAWTs have demonstrated acceptable efficiency; however, their reliance on initial torque and challenges associated with self-starting capabilities prompted advancements in hybrid Darrieus-Savonius VAWTs. This configuration has primarily proven effective in enhancing efficiency within a low-tip speed ratio (TSR) range. However, hybrid rotors tend to experience performance degradation in high-TSR ranges. To address the performance decline observed in the high-TSR range, this study proposes an innovative solution by developing a dual-shaft hybrid rotor. This design functions as a control mechanism to prevent the angular velocity of the inner Savonius rotor from exceeding a specified threshold. For the first time, this design integrates Darrieus and Savonius rotors on a common shaft, then with two distinct rotors mounted on separate shafts. These shafts are connected through a gearless control mechanism that regulates the angular velocity of the Savonius rotor, ensuring it operates below an angular velocity of 19.79 rad/s. The findings suggest that both single and dual shaft configurations can improve rotor power coefficient Cp by up to 72% and 90%, respectively, in comparison to conventional rotors at a TSR of 1.4.
Keywords
Self-starting capability
Single-shaft hybrid Darrieus-Savonius VAWT
Dual-shafthybrid Darrieus-Savonius VAWT
Gear mechanism
Vorticity field
Subjects
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Modares Mechanical Engineering
Volume 25, Issue 9
September 2025
Pages 595-601