Turbine rotor assembly, turbine, and rotor blade

A turbine rotor assembly comprising:

• a rotor shaft on which a blade groove extending along a circumferential direction is formed;
• and
• a plurality of rotor blades each including:
• a blade section disposed on an outer side of the rotor shaft in a radial direction of the rotor shaft;
• and
• a blade root section integrally formed with the blade section and is fit in the blade groove, wherein
• the rotor shaft includes:
• two protrusions which are separated from each other in an axial direction of the rotor shaft and form a part of a wall surface of the blade groove and an opening of the blade groove, the two protrusions each protruding outward from an outer circumferential surface of the rotor shaft in the radial direction of the rotor shaft;
• two bearing surfaces disposed on an inner side of the outer circumferential surface of the rotor shaft in the radial direction of the rotor shaft to face inward in the radial direction of the rotor shaft, the two bearing surfaces being separated from each other in the axial direction of the rotor shaft and forming a part of the wall surface of the blade groove;
• two first facing surfaces which face each other in the axial direction of the rotor shaft and form a part of the wall surface of the blade groove, the first facing surfaces being disposed between the bearing surfaces and outer circumferential surfaces of the protrusion in the radial direction of the rotor shaft;
• and
• two second facing surfaces disposed between the bearing surfaces and the outer circumferential surfaces of the protrusions in the radial direction of the rotor shaft, on an outer side of the two first facing surfaces, the two second facing surfaces facing each other in the axial direction of the rotor shaft with a gap therebetween larger than a gap between the first facing surfaces and forming a part of the wall surface of the blade groove, and
• the blade root section of each of the rotor blades includes:
• two contact surfaces which are separated from each other in the axial direction of the rotor shaft, and are contactable with the two bearing surfaces in the radial direction of the rotor shaft, respectively;
• two first side surfaces each facing a corresponding one of the two first facing surfaces;
• two second side surfaces each facing a corresponding one of the two second facing surfaces with a gap therebetween that is smaller than a distance between the first facing surface and the first side surface;
• and
• two flange sections which are each positioned, when the blade root section of the rotor blade is assembled to the blade groove formed on the rotor shaft, adjacent to the outer circumferential surface of a corresponding one of the two protrusions in the radial direction of the rotor shaft, the flange sections forming a part of a platform section continuing to a blade profile section of the rotor blade.