Axial turbine

Patent metadata

Field	Value
Publication number	US-10301970-B2
Application number	US-201615182707-A
Country	US
Kind code	B2
Filing date	Jun 15, 2016
Priority date	Jun 18, 2015
Publication date	May 28, 2019
Grant date	May 28, 2019

Abstract

An axial turbine includes an upstream turbine stage that includes: a cover disposed at a distal end of an upstream bucket and opposed to an inner wall of an upstream diaphragm outer ring across a gap; and a downstream diaphragm outer ring that is disposed downstream of the upstream turbine stage and that has an inner peripheral-side end wall shaped into a flare. The inner peripheral-side end wall of the downstream diaphragm outer ring has a flare angle formed to be greater than a slant angle of an inner peripheral-side wall of the cover. In the axial turbine, the inner peripheral-side end wall of the downstream diaphragm outer ring is formed to have a meridional shape that has at least one inflection point between the upstream turbine stage and a downstream turbine stage and such that a tangent at the inflection point with respect to a steam flow direction has a positive gradient.

First claim

What is claimed is:

1. An axial turbine, comprising:
an upstream turbine stage including:
a plurality of upstream nozzles arrayed in a tangential direction between an upstream diaphragm outer ring and an upstream diaphragm inner ring;
a plurality of upstream buckets disposed on an outer peripheral side of a turbine rotor and arrayed in the tangential direction; and
a cover disposed at a distal end of at least one of the upstream buckets and opposed to an inner wall of the upstream diaphragm outer ring across a gap; and
a downstream turbine stage including:
a downstream diaphragm outer ring disposed downstream of the upstream turbine stage, the downstream diaphragm outer ring having an inner peripheral-side end wall shaped into a flare;
a plurality of downstream nozzles arrayed in the tangential direction between the downstream diaphragm outer ring and a downstream diaphragm inner ring; and
a plurality of downstream buckets disposed on the outer peripheral side of the turbine rotor and arrayed in the tangential direction,
the inner peripheral-side end wall of the downstream diaphragm outer ring having a flare angle formed to be greater than a slant angle of an inner peripheral-side wall of the cover,
wherein the inner peripheral-side end wall of the downstream diaphragm outer ring has a meridional shape curved into an S-shape that has an inflection point between the at least one of the upstream buckets and a front edge of the downstream nozzle such that a tangent at the inflection point with respect to a steam flow direction has a positive gradient.

2. The axial turbine according to claim 1 ,
wherein a radius position of the inner peripheral-side end wall of the upstream diaphragm outer ring, the radius position being opposed to an outer peripheral-side wall of the cover, is located outer side in a radius direction than a minimum radius position of the inner peripheral-side wall of the downstream diaphragm outer ring.

3. The axial turbine according to claim 1 ,
wherein the meridional shape of the inner peripheral-side end wall of the downstream diaphragm outer ring disposed between the upstream turbine stage and the downstream turbine stage is formed using a Bezier curve.

Assignees

• Mitsubishi Hitachi Power Sys

Inventors

• Fukushima Hisataka
• Kudo Takeshi
• Senoo Shigeki
• Ono Hideki

Classifications

• F01D9/041

  using blades (F01D5/148 takes precedence) · CPC title

• F05D2220/31

  in steam turbines · CPC title

• F01D5/12

  Blades ({specially adapted for radial flow machines or engines F01D5/04}; blade roots F01D5/30; rotors with blades adjustable in operation F01D7/00; stator blades F01D9/02) · CPC title

• F01D25/24 Primary

  Casings (modified for heating or cooling F01D25/14); Casing parts, e.g. diaphragms, casing fastenings (casings for rotary machines or engines in general F16M {; special arrangements in stators dealing with breaking-off of part of rotor F01D21/045}) · CPC title

• F01D5/225

  by shrouding · CPC title