Axial flow turbine

摘要

An axial flow turbine that can enhance an effect of reducing a mixing loss is disclosed. The axial flow turbine includes a plurality of stator blades provided on the inner circumferential side of a diaphragm outer ring; a plurality of rotor blades provided on the outer circumferential side of a rotor; a shroud provided on the outer circumferential side of the plurality of rotor blades; an annular groove portion formed in the diaphragm outer ring and housing the shroud therein; a clearance passage defined between the groove portion and the shroud, into which a portion of working fluid flows from the downstream side of the stator blades in a main passage; seal fins provided in the clearance passage; a circulation flow generating chamber defined on the downstream side of the clearance passage; and a plurality of shielding plates secured to the diaphragm outer ring.

主权项

1. An axial flow turbine comprising:
a plurality of stator blades provided on the inner circumferential side of a stationary body and circumferentially arranged; a plurality of rotor blades provided on the outer circumferential side of a rotating body and circumferentially arranged; a main passage in which the stator blades and the rotor blades on the downstream side of the stator blades are arranged, the main passage through which working fluid flows; a shroud provided on the outer circumferential side of the rotor blades; an annular groove portion formed in the stationary body and housing the shroud therein; a clearance passage formed between the groove portion and the shroud, wherein a portion of the working fluid flows from the downstream side of the stator blades in the main passage into the clearance passage and flows out toward the downstream side of the rotor blades in the main passage; a plurality of stages of seal fins provided in the clearance passage; a circulation flow generating chamber defined on the downstream side of the clearance passage; and a plurality of shielding plates secured to the stationary body in such a manner as to be located in the circulation flow generating chamber, the shielding plates extending in axial and radial directions of the rotating body, wherein provided is an annular first projecting portion projecting from a downstream-side lateral surface of the groove portion toward a downstream-side end face of the shroud, and the circulation flow generating chamber is defined by a portion of an inner circumferential surface of the groove portion located on the downstream side of a final stage seal fin of the stages of seal fins, the downstream-side lateral surface of the groove portion, and an outer circumferential surface of the first projecting portion.