Axial turbine

An axial turbine comprising:

• a plurality of stages, each of the plurality of stages including stationary blades adjacent to each other along the turbine circumferential direction and corresponding moving blades adjacent to each other along the circumferential direction, each of the moving blades being located downstream of a corresponding one of the stationary blades along a flow direction of a working fluid, so as to be opposed to the corresponding stationary blade,
• wherein each of the stationary blades is formed so that the intersection line between the outer periphery of the stationary blade constituting a stage having moving blades longer than moving blades in a preceding stage and a plane containing the central axis of the turbine, has a flow path constant diameter portion that includes at least an outlet portion of the stationary blade and that is parallel to the central axis of the turbine,
• wherein a height of the flow path constant diameter portion in the turbine radial direction substantially equals a height in the turbine radial direction, of a flow path effective range outer peripheral portion of the moving blade in the stage, and
• wherein the stationary blade is formed so that the intersection line between the outer periphery thereof and a plane containing the central axis of the turbine has a flow path enlarged diameter portion that inclines to the outer peripheral side in the turbine radial direction, toward the downstream side along the flow direction of the working fluid, and that is located upstream of the flow path constant diameter portion.