Airfoil and mechanical machine having the same

An airfoil comprising:

• an airfoil portion having an airfoil surface extending along a spanwise direction between a leading edge and a trailing edge;
• and
• at least one communication hole extending at least in the airfoil portion and having a first opening end opened to the airfoil surface, through which the first opening end is communicated with a second opening end provided in a portion of the airfoil other than the airfoil portion or a device on which the airfoil is installed,
• wherein, on a cross-section perpendicular to the spanwise direction through a position of the first opening end of the spanwise direction, an angle A1 satisfying a condition (a) exists within an angle range equal to or larger than −10 degrees and equal to or smaller than 10 degrees with respect to an extension line obtained by extending a camber line of the airfoil portion from the leading edge while setting the leading edge as a center, and
• wherein the condition (a) is a condition that a static pressure at a position of the first opening end is equal to a static pressure at a position of the second opening end when the airfoil portion receives a fluid flow from a direction of the angle A1 toward the leading edge.