Rotor disk, turbine blade, and turbine blade assembly equipped with these

A turbine blade comprising:

• a blade body which has an airfoil-shaped cross section and extends in a blade height direction perpendicular to the cross section;
• and
• a blade root which is provided on a second blade height side of the blade body between a first blade height side and the second blade height side of the blade height direction and is fitted into a blade root groove of a rotor disk having a disk shape centered on an axis,
• wherein the blade body includes a leading edge, a trailing edge, a concave curved pressure surface which connects the leading edge and the trailing edge, and a convex curved suction surface which connects the leading edge and the trailing edge,
• wherein the blade root includes a front-end surface which faces a front side which is a side where the leading edge is present with respect to the trailing edge, a rear-end surface which faces a rear side opposite to the front side, and a side surface which connects an edge of the front-end surface and an edge of the rear-end surface,
• wherein the side surface of the blade root includes a pair of neck surfaces, a pair of bearing surfaces, a pair of disk neck facing curved surfaces, and a bottom surface,
• wherein a first neck surface which is one surface of the pair of neck surfaces spreads in a direction having a component on the blade height direction,
• wherein a second neck surface which is the other surface of the pair of neck surfaces spreads in a direction having a component on the blade height direction, faces the first neck surface in a lateral direction along the front-end surface to be perpendicular to the blade height direction, and is located on a second lateral side of the lateral direction with respect to the first neck surface,
• wherein a first bearing surface which is one surface of the pair of bearing surfaces is an inclined plane which gradually extends toward a first lateral side of the lateral direction as the first bearing surface extends from an edge on the second blade height side of the first neck surface toward the second blade height side,
• wherein a second bearing surface which is the other surface of the pair of bearing surfaces is an inclined plane which gradually extends toward the second lateral side as the second bearing surface extends from an edge on the second blade height side of the second neck surface toward the second blade height side and faces the first bearing surface in the lateral direction,
• wherein a first disk neck facing curved surface which is one surface of the pair of disk neck facing curved surfaces includes a first disk neck facing outer curved surface which gradually extends toward the first lateral side as the first disk neck facing outer curved surface extends from an edge on the second blade height side of the first bearing surface toward the second blade height side, and a first disk neck facing inner curved surface which gradually extends toward the second lateral side as the first disk neck facing inner curved surface extends from a first peak position corresponding to an edge on the second blade height side of the first disk neck facing outer curved surface toward the second blade height side,
• wherein a second disk neck facing curved surface which is the other surface of the pair of disk neck facing curved surfaces includes a second disk neck facing outer curved surface which gradually extends toward the second lateral side as the second disk neck facing outer curved surface extends from an edge on the second blade height side of the second bearing surface toward the second blade height side, and a second disk neck facing inner curved surface which gradually extends toward the first lateral side as the second disk neck facing inner curved surface extends from a second peak position corresponding to an edge on the second blade height side of the second disk neck facing outer curved surface toward the second blade height side,
• wherein the second disk neck facing outer curved surface faces the first disk neck facing outer curved surface in the lateral direction,
• wherein the second disk neck facing inner curved surface faces the first disk neck facing inner curved surface in the lateral direction,
• wherein the second peak position faces the first peak position in the lateral direction,
• wherein the bottom surface is a plane which faces the second blade height side and connects an edge on the second blade height side of the first disk neck facing inner curved surface and edge on the second blade height side of the second disk neck facing inner curved surface,
• wherein the first disk neck facing outer curved surface includes a first curvature changing surface of which a curvature gradually increases from the first peak position toward the first blade height side, the first curvature changing surface being an elliptical arc surface defined by a part of a first ellipse determined by two focal points arranged in the blade height direction inside the blade root, and
• wherein the second disk neck facing outer curved surface includes a second curvature changing surface of which a curvature gradually increases from the second peak position toward the first blade height side, the second curvature changing surface being an elliptical arc surface defined by a part of a second ellipse determined by two focal points arranged in the blade height direction inside the blade root.