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Unsteady flow past an automatically rotating vertical-axis wind turbine (VAWT), which consists of three quarter circular-arc blades attached to a cylindrical core, is computationally simulated by a vortex particle method. Such a dynamic simulation for the autorotation requires non grid-based strategy. In this computation, the angular velocity of the rotor is successfully updated by solving the equation of motion with the use of the computed aerodynamic torque on all blades, which results in the problem of one degree of freedom (1-DOF). Results for torque characteristics, temporal angular velocity of the rotor and snapshots of iso-vorticity line and streamline around the rotor are given. The present computational strategy could play a key role for computing the autorotaion of a rotor.

This works is intended to explore the effects of the pitching motion of blades on the performance of a vertical-axis wind turbine (VAWT) with straight blades.We designed a vertical-axis wind turbine with the variable-pitch angle mechanism, which consists of a blade and a four-bar linkage.When the turbine is driven by a wind, the pitch angle of blade varies sinusoidally without actuators.We measured the performance of VAWT by using an open circuit type wind tunnel.We estimated the power loss due to pitching motion of blades is proportional to the inertia moment of blades and the cube of turbine rotational speed.The experimental values agree with the theoretical results approximately. The power of VAWT decreases with increasing of the inertia moment of blades, the turbine rotational speed and the blades pitch angle amplitude.