Axial flow rotating machine and diffuser

Patent metadata

Field	Value
Publication number	US-10753217-B2
Application number	US-201916379931-A
Country	US
Kind code	B2
Filing date	Apr 10, 2019
Priority date	Mar 29, 2013
Publication date	Aug 25, 2020
Grant date	Aug 25, 2020

Abstract

An axial flow rotating machine has: a rotor with a plurality of rotor blades; a stator with a plurality of stator blades; an axial flow rotating portion defined by the rotor and the stator; and a diffuser connected to the axial flow rotating portion on a downstream side of the axial flow rotating portion. A final blade portion inner-circumferential inner wall, which is a portion of an inner-circumferential inner wall of the axial flow rotating portion, is defined such that a diameter thereof at a trailing edge position of a final blade is smaller than the diameter at a leading edge position of the final blade. In addition, a diameter of all or a portion of a diffuser inner-circumferential inner wall decreases in a direction of the downstream side in an axial direction.

First claim

The invention claimed is:

1. A diffuser configured to be connected to a final-stage rotor blade of a turbine on a downstream side of the final-stage rotor blade, the diffuser comprising:
an outer-circumferential inner wall;
an inner-circumferential inner wall; and
a strut cover,
wherein:
the outer-circumferential inner wall is positioned on an outer circumferential side of the inner-circumferential inner wall such that the outer-circumferential inner wall is separated from the inner-circumferential inner wall and a circular flow path is defined between the outer-circumferential inner wall and the inner-circumferential inner wall;
the strut cover connects the inner-circumferential inner wall and the outer-circumferential inner wall in a radial direction inside the circular flow path;
the inner-circumferential inner wall includes a first inclination portion and a second inclination portion downstream of the first inclination portion;
the first inclination portion is a straight linear portion inclined at a first inclination angle in a cross section of the diffuser along an axial direction;
the second inclination portion is a straight linear portion inclined at a second inclination angle in the cross section of the diffuser along the axial direction;
the first inclination angle is different from the second inclination angle;
a diameter of the inner-circumferential inner wall along the second inclination portion decreases in a direction of a downstream side in the axial direction; and
an end of the first inclination portion is between a leading edge position of the strut cover and a trailing edge position of the strut cover in the axial direction.

2. The diffuser according to claim 1 , wherein the first inclination portion and the second inclination portion are connected at a position between the leading edge position of the strut cover and the trailing edge position of the strut cover in the axial direction.

3. The diffuser according to claim 2 , wherein the position between the leading edge position of the strut cover and the trailing edge position of the strut cover in the axial direction is a position between a throat position and the trailing edge position of the strut cover in the axial direction.

4. The diffuser according to claim 2 , wherein:
the second inclination angle is equal to or greater than the first inclination angle; and
the second inclination angle is less than 0 degrees.

5. The diffuser according to claim 1 , wherein:
the second inclination angle is equal to or greater than the first inclination angle; and
the second inclination angle is less than 0 degrees.

6. The diffuser according to claim 1 , wherein:
the diameter of the inner-circumferential inner wall along the second inclination portion is a second diameter; and
a first diameter of the inner-circumferential inner wall along the first inclination portion increases in the direction of the downstream side in the axial direction.

7. The diffuser according to claim 1 , wherein a cross section of the strut cover is blade-shaped.

8. A diffuser configured to be connected to a final-stage rotor blade of a turbine on a downstream side of the final-stage rotor blade, the diffuser comprising:
an outer-circumferential inner wall;
an inner-circumferential inner wall; and
a strut cover,
wherein:
the outer-circumferential inner wall is positioned on an outer circumferential side of the inner-circumferential inner wall such that the outer-circumferential inner wall is separated from the inner-circumferential inner wall and a circular flow path is defined between the outer-circumferential inner wall and the inner-circumferential inner wall;
the strut cover connects the inner-circumferential inner wall and the outer-circumferential inner wall in a radial direction inside the circular flow path;
the inner-circumferential inner wall includes a first portion and a second portion downstream of the first portion;
the first portion is a straight linear portion disposed at a first angle in a cross section of the diffuser along an axial direction;
the second portion is a straight linear portion disposed at a second angle in the cross section of the diffuser along the axial direction;
the first angle is different from the second angle;
a diameter of the inner-circumferential inner wall along the first portion decreases in a direction of a downstream side in the axial direction; and
the first portion and the second portion are connected at a position between a leading edge position of the strut cover and a trailing edge position of the strut cover in the axial direction.

Assignees

• Mitsubishi Heavy Ind Ltd

Inventors

• Nishimura Kazuya
• Ito Eisaku
• Iida Koichiro
• AKIMOTO Kentaro

Classifications

• F01D25/30

  Exhaust heads, chambers, or the like · CPC title

• F05D2250/324

  divergent · CPC title

• F01D5/143 Primary

  Contour of the outer or inner working fluid flow path wall, i.e. shroud or hub contour · CPC title

• F04D29/542

  Bladed diffusers (fixing blades to stators F01D9/042) · CPC title

• F04D29/547

  having a special shape in order to influence fluid flow · CPC title