Patent attributes
A leading edge of a blade has a first curved portion provided with a leading-edge rearmost point, and a trailing edge of the blade has a second curved portion located on the inner circumferential side of the trailing edge and a third curved portion located on the outer circumferential side of the blade on the trailing edge. The third curved portion has a trailing-edge foremost point, and the second curved portion has a trailing-edge rearmost point. The trailing edge and a first concentric circle, which is one of concentric circles having as their center an axis of rotation and passes through the leading-edge rearmost point, intersect each other at a first intersection. The first intersection is located between the trailing-edge rearmost point and the trailing-edge foremost point.