Rotor blade and gas turbine provided with same

A rotor blade comprising:

• a blade body that has a cross section forming an airfoil and that extends in a blade height direction including a direction component perpendicular to the cross section;
• a platform that is provided at an end of a hub side of the blade body, out of a tip side and the hub side in the blade height direction;
• a blade root that is provided on the hub side of the platform;
• and
• a cooling air passage that is formed over the blade root, the platform, and the blade body and through which cooling air is allowed to be circulated,
• wherein the blade body has a blade surface facing a direction having a direction component perpendicular to the blade height direction, and a tip surface facing the tip side in the blade height direction,
• the blade surface has a leading edge and a trailing edge extending in the blade height direction, and a positive pressure surface and a negative pressure surface spreading from the leading edge to the trailing edge,
• the cooling air passage includes
• a main passage that has an inlet which is open on a surface of the blade root and into which cooling air is able to flow,
• a plurality of leading ejection holes that include a leading ejection port open in a leading edge peripheral portion, which is a portion that includes the leading edge and faces a leading side which is a side of the leading edge with respect to the trailing edge, in the blade surface, and through which the cooling air that has been passed through the main passage is allowed to be ejected from the leading ejection ports, and
• a plurality of film holes that include a blade surface ejection port which excludes the leading edge peripheral portion, in the blade surface, and is open in at least one blade surface of the positive pressure surface and the negative pressure surface, and through which the cooling air that has been passed through the main passage is allowed to be ejected to an outside along the at least one blade surface from the blade surface ejection port,
• the main passage has an introduction passage portion that extends from the inlet to a boundary between the platform and the blade body, and a blade body cooling passage portion that has three or more odd-numbered intra-blade passages extending in the blade height direction in the blade body,
• the odd-numbered intra-blade passages are arranged from the introduction passage portion to the leading side along a camber line of the blade body,
• intra-blade passages adjacent to each other among the odd-numbered intra-blade passages communicate with each other at one end out of an end on the hub side and an end on the tip side such that the blade body cooling passage portion configures one serpentine passage in which a passage meanders in the blade height direction,
• the plurality of leading ejection holes communicate with a first intra-blade passage positioned on a most leading side among the odd-numbered intra-blade passages,
• the plurality of film holes communicate with at least one intra-blade passage of the first intra-blade passage and a second intra-blade passage adjacent to the first intra-blade passage among the odd-numbered intra-blade passages, and
• an aperture ratio which is an area of the blade surface ejection port per unit area on the hub side is higher than an aperture ratio which is an area of the blade surface ejection port per unit area on the tip side, based on a middle position of the blade body in the blade height direction.