Rotor blade of axial-flow fluid machine

A rotor blade of an axial-flow fluid machine comprising:

• a blade portion that extends in a spanwise direction from a hub portion to a tip portion and has a pressure-side surface and a suction-side surface,
• wherein the blade portion is formed by profiles with airfoil shapes stacked in the spanwise direction,
• wherein a stacking line connecting gravity centers of the profiles at each spanwise position
• is a straight line parallel to a radial direction at a part from the hub portion to an outer end of a secondary flow region in a vicinity of the hub portion, and
• is a curved line, along which a distance measured from the straight line toward a side of the suction-side surface in a circumferential direction gradually increases toward the tip portion, at a part from the outer end of the secondary flow region to the tip portion, and
• wherein a distance from the hub portion to a connecting point between the straight line and the curved line is 20% of an entire height of the blade portion.