Numerical investigation of a novel vertical axis wind turbine with controllable blades

In order to reduce the negative torque of drag-type vertical axis wind turbines (VAWTs) in the returning direction, a novel VAWT with retractable blades is proposed. Controlled by a link mechanism, the blades can be entirely hidden in the windshield in the returning direction and negative torques can then be considerably reduced. With the aim of further investigating the torque and power property of the turbine, two-dimensional computational fluid dynamics (CFD) simulations were carried out with a sliding mesh method. The effects of blade number and rotation speed were considered as well. The results and their analysis preliminarily demonstrated that the blade generates nearly no negative torque in the returning direction. The maximum averaged power coefficient is 0.2449, obtained at a flow coefficient of 0.4.