Although the drag-force-type wind turbine has a large starting torque, the output is often lower in comparison with a lift force type wind turbine of the same size. In addition, when applying the wind collecting effect in the horizontal axis wind turbine, it is necessary to follow the wind direction. Therefore, we focused on a multi-blade vertical axis wind turbine with a drag-force-type which is no directivity to the wind direction and has a large torque in the low rotational speed region. The drag-force-type multi-blade vertical axis wind turbine with stationary vanes proposed in this paper, improvement of output characteristics is attempted by providing stationary vanes for collecting and rectifying wind stream effect around rotating blades generating torque by rotating. In this paper, the output characteristics of a drag type multi-blade vertical axis wind turbine with stationary vanes are clarified by wind tunnel experiments. In the experiment, torque characteristics with respect to the rotational speed at each wind speed were obtained by using a rotational speed detector and a torque detector. Moreover, in order to investigate the influence of stationary vanes on rotating multi-blades, output characteristics when stationary vanes were removed were measured and compared with output characteristics when stationary vanes were attached. From the result of the output characteristics by the wind tunnel experiment, the output was increased as compared with the case without the stationary vanes installed.
Propeller wind turbines are now widely used as wind power generators and connected to utility grids. Although propeller wind turbines, which are lift-force-type wind turbines, offer the advantage of relatively high efficiency, they also have the disadvantage that, as a horizontal axis wind turbine, they require the rotor to always face into the wind since. Because of this, if they are installed in a location where the wind direction varies, the amount of generated power is lowered. In contrast, vertical axis wind turbines rotate independently of the wind direction, making them useful for locations with wind that varies in direction. However, lift-force-type wind turbines, such as the Darrieus wind turbine, that focus on efficiency may require a starter device (Rajaoferson and Comolet, 1985). Drag-force-type vertical axis wind turbines, on the other hand, do not require a starter device since the starting torque is large, but the efficiency is often lower than in liftforce-type vertical axis wind turbines.
