Study on the optimal design of vertical axis wind turbine with novel variable solidity type for self-starting capability and aerodynamic performance

This study designs a novel variable solidity Darrieus-type vertical axis wind turbine (D-VAWT) to solve the self-starting problem and optimize the aerodynamic performance. Two dynamic methods based on computational fluid dynamics are used to simulate different operation phases of the D-VAWT. Research results show that the solidity (σ) and moment of inertia (Jz) have a greater effect on the self-starting capability. With the increase of σ, the self-starting capability increases. The D-VAWT with σ ≥ 0.417 can achieve self-starting with a starting-up time of fewer than 30s under the condition of 7.9 m/s incoming wind. Small solidity (σ = 0.417) D-VAWT has a wider tip speed ratio (λ) operating range and generates electricity stably under the generator load. The σ of the D-VAWT in the self-starting phase is 0.83 and in the power generation operation phase is 0.417. The maximum power coefficient （Cp） is 0.342 with the optimal λ of 3.25. Compared with the fixed solidity (σ = 0.83) D-VAWT, the maximum power of a single D-VAWT increased from 53.42W to 100.39W to increase the maximum power by 188%.