| 摘要 |
PROBLEM TO BE SOLVED: To improve turbine-stage efficiency by circumferentially disposing a plurality of nozzles in an annular passage formed between inner and outer rings of a nozzle diaphragm such that the nozzles are tilted in the circumferential direction of the turbine, and specifying an axial distance from the end of the trailing blade-edge of the nozzle, i.e., the end at which the trailing blade- edge of the nozzle forms an acute angle, to the downstream end of a wall. SOLUTION: In an annular passage defined between an annular inner ring 21R and an annular outer ring 21T of a nozzle diaphragm, a plurality of nozzles 10 are successively disposed in the circumferential direction. Rotor blades 41 are disposed downstream of the nozzles 10, thereby forming an axial-flow turbine. A trailing blade-edge 12 of each nozzle 10 is circumferentially tilted to form an acute angleθR with a tangent line 23R of an inner peripheral wall 20R at an inner end 12R of the trailing blade-edge 12. An axial distance LR from the inner end 12R of the trailing blade-edge 12 to a downstream end 22R of the inner peripheral wall 20R is larger than an axial distance LT from an outer end 12T of the trailing blade-edge 12 to a downstream end 22T of an outer peripheral wall. Thus, a fast flow can be retained, whereby turbine-stage loss is reduced.
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