Axial flow rotating machine and diffuser

Patent metadata

Field	Value
Publication number	US-10760438-B2
Application number	US-201414771913-A
Country	US
Kind code	B2
Filing date	Mar 20, 2014
Priority date	Mar 29, 2013
Publication date	Sep 1, 2020
Grant date	Sep 1, 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. An axial flow rotating machine comprising:
a rotor that includes a plurality of rotor blades and is configured to freely rotate around an axial line;
a stator that includes a plurality of stator blades adjacent to the plurality of rotor blades;
an axial flow rotating portion that is defined by the rotor and the stator; and
a diffuser that is connected to the axial flow rotating portion on a downstream side of the axial flow rotating portion and that extends in an axial direction to define a circular flow path;
wherein:
an inner-circumferential inner wall of the diffuser includes a first inclination portion and a second inclination portion located downstream of the first inclination portion;
the second inclination portion is continuous with the first inclination portion;
the first inclination portion and the second inclination portion are inclined in opposite directions whereby the first inclination portion is inclined toward an outer-circumferential inner wall of the diffuser and the second inclination portion is inclined away from the outer-circumferential inner wall of the diffuser;
the second inclination portion extends from the first inclination portion to a downstream end of the inner-circumferential inner wall of the diffuser such that a diameter of the inner-circumferential inner wall of the diffuser decreases over an entirety of the second 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 the axial direction; and
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.

2. The axial flow rotating machine according to claim 1 , wherein a final blade portion inner-circumferential inner wall, which is a portion of an inner-circumferential inner wall of the axial flow rotating portion corresponding to an axial-direction position of a final blade located furthest downstream among the plurality of rotor blades and the plurality of stator blades, is defined such that a diameter of the final blade portion inner-circumferential inner wall at a trailing edge position of the final blade is smaller than the diameter of the final blade portion inner-circumferential inner wall at a leading edge position of the final blade.

3. The axial flow rotating machine according to claim 2 , wherein an average inclination angle of the inner-circumferential inner wall of the diffuser is equal to or greater than an average inclination angle of the final blade portion inner-circumferential inner wall from a leading edge to a trailing edge of the final blade on the final blade portion inner-circumferential inner wall and is less than 0 degrees.

4. The axial flow rotating machine according to claim 2 , wherein:
the final blade is a final-stage rotor blade of a turbine and the diffuser is connected to the final-stage rotor blade on a downstream side of the final-stage rotor blade; and
the diameter of the final blade portion inner-circumferential inner wall starts decreasing from a position between a leading edge and a throat position of the final-stage rotor blade.

5. The axial flow rotating machine according to claim 1 , wherein a distance between the inner-circumferential inner wall of the diffuser and the outer-circumferential inner wall of the diffuser is narrowest at an inlet of the diffuser.

6. An axial flow rotating machine comprising:
a rotor that includes a plurality of rotor blades and is configured to freely rotate around an axial line;
a stator that includes a plurality of stator blades adjacent to the plurality of rotor blades;
an axial flow rotating portion that is defined by the rotor and the stator; and
a diffuser that is connected to the axial flow rotating portion on a downstream side of the axial flow rotating portion and that extends in an axial direction to define a circular flow path;
wherein:
an inner-circumferential inner wall of the diffuser includes a first inclination portion and a second inclination portion located downstream of the first inclination portion;
the second inclination portion is continuous with the first inclination portion;
each of the first inclination portion and the second inclination portion is inclined away from an outer-circumferential inner wall of the diffuser;
the first inclination portion is a straight linear portion inclined at a first inclination angle in a cross section of the diffuser along the 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; and
the first inclination angle is different from the second inclination angle.

7. The axial flow rotating machine according to claim 6 , wherein the second inclination portion extends from the first inclination portion to a downstream end of the inner-circumferential inner wall of the diffuser.

8. The axial flow rotating machine according to claim 6 , further comprising:
a final blade portion inner-circumferential inner wall, which is a portion of an inner-circumferential inner wall of the axial flow rotating portion corresponding to an axial-direction position of a final blade located furthest downstream among the plurality of rotor blades and the plurality of stator blades, and is defined such that a diameter of the final blade portion inner-circumferential inner wall at a trailing edge position of the final blade is smaller than the diameter of the final blade portion inner-circumferential inner wall at a leading edge position of the final blade.

9. The axial flow rotating machine according to claim 8 , wherein an average inclination angle of the inner-circumferential inner wall of the diffuser is equal to or greater than an average inclination angle of the final blade portion inner-circumferential inner wall from a leading edge to a trailing edge of the final blade on the final blade portion inner-circumferential inner wall and is less than 0 degrees.

Assignees

• Mitsubishi Heavy Ind Ltd

Inventors

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

Classifications

• F05D2220/32

  in gas turbines · CPC title

• F04D29/542

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

• F01D5/143 Primary

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

• F05D2250/324

  divergent · CPC title

• F01D25/30

  Exhaust heads, chambers, or the like · CPC title