Abstract: A vertical axis windmill is provided with a plurality of blades arranged at equidistant angular intervals with the vertical axis of rotation as the center in a plane perpendicular to a vertical axis of rotation, wherein the blade has a streamlined airfoil having a lift coefficient of 1.0 or more, comprising: an opening/closing member of which the front-end part is pivotally supported by the back side of the blade; and of which the rear-end part opens/closes with respect to the blade, and opening/closing control means for controlling the opening/closing action of the opening/closing member in response to the ratio of the rotational speed of the blade to a wind speed.

Abstract: A windmill for highly efficient wind power generation is provided by enabling one to efficiently rotate the windmill even in starting or at a low wind speed region by improving a blade of a vertical shaft type windmill of a lift type. In the windmill for wind power generation, a plurality of blades are provided in parallel with a rotating shaft in a face orthogonal to the vertical rotating shaft at constant angles centering on the rotating shaft, wherein the blade is of a blade type having a high lift coefficient at low Reynolds number and a notch portion is formed at a rear edge portion of a lower face of the blade.

Abstract: The invention resides in providing a windmill for highly efficient wind power generation by enabling to efficiently rotate the windmill even in starting or at a low wind speed region by improving a blade of a vertical shaft type windmill of a lift type. In a windmill for wind power generation in which a plurality of blades are provided in parallel with a rotating shaft in a face orthogonal to the vertical rotating shaft at constant angles centering on the rotating shaft, the blade is of a blade type having a high lift coefficient at low Raynolds number and a notch portion is formed at a rear edge portion of a lower face of the blade.