Turbine blade and gas turbine

Patent metadata

Field	Value
Publication number	US-10697311-B2
Application number	US-201515514649-A
Country	US
Kind code	B2
Filing date	Oct 20, 2015
Priority date	Nov 20, 2014
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

A turbine rotor blade includes an airfoil portion having an airfoil defined by a pressure surface and a suction surface; and a squealer rib on a tip surface of the turbine rotor blade, the squealer rib extending from a leading-edge side (toward a trailing-edge side. The squealer rib has a ridge extending in an extending direction of the squealer rib. The turbine rotor blade is configured to provide a clearance between the tip surface of the turbine rotor blade and an inner wall surface of a casing of a turbine such that the inner wall surface of the casing of the turbine faces the tip surface of the turbine rotor blade and the clearance has a local minimum value on the ridge. The clearance is greater than the local minimum value at both sides of the ridge in a width direction of the squealer rib.

First claim

The invention claimed is:

1. A turbine rotor blade for a turbine, the turbine rotor blade comprising:
an airfoil portion having an airfoil defined by a pressure surface and a suction surface; and
a squealer rib on a tip surface of the turbine rotor blade, the squealer rib extending from a leading-edge side of the turbine rotor blade toward a trailing-edge side of the turbine rotor blade,
wherein the squealer rib has a ridge extending in an extending direction of the squealer rib,
wherein the tip surface of the turbine rotor blade is configured to face an inner wall surface of a casing of the turbine,
wherein the turbine rotor blade is configured to provide a clearance between the tip surface of the turbine rotor blade and the inner wall surface of the casing of the turbine such that the clearance has a local minimum value on the ridge,
wherein the clearance is greater than the local minimum value at an axially inner side of the ridge in a width direction of the squealer rib,
wherein the squealer rib has a narrowing surface between the ridge and a pressure-side edge of the squealer rib on a pressure side of the squealer rib,
wherein the ridge is at an intersection between the narrowing surface and the suction surface of the airfoil portion, and
wherein a slope of the narrowing surface is constant over an entire length of the narrowing surface from the pressure-side edge of the squealer rib toward the ridge such that the narrowing surface is configured to monotonically reduce the clearance from the pressure-side edge of the squealer rib toward the ridge.

2. The turbine rotor blade according to claim 1 ,
wherein the squealer rib is a first squealer rib, the ridge is a first ridge, the clearance is a first clearance, the local minimum value is a first local minimum value, and the turbine rotor blade further comprises a second squealer rib,
wherein the second squealer rib has a second ridge extending in an extending direction of the second squealer rib,
wherein the turbine rotor blade is configured to provide a second clearance between the tip surface of the turbine rotor blade and the inner wall surface of the casing of the turbine such that the second clearance has a second local minimum value on the second ridge,
wherein the second squealer rib has a receding surface between the second ridge and a suction-side edge of the second squealer rib on a suction side of the second squealer rib,
wherein the second ridge is closer to a pressure side of the second squealer rib than the suction-side edge of the second squealer rib,
wherein the second ridge is at an intersection between the receding surface and the pressure surface of the airfoil portion, and
wherein a slope of the receding surface is constant over an entire length of the receding surface from the suction-side edge of the second squealer rib toward the second ridge such that the receding surface is configured to monotonically increase the second clearance from the second ridge toward the suction-side edge of the second squealer rib.

3. The turbine rotor blade according to claim 1 ,
wherein the squealer rib is a first squealer rib and the turbine rotor blade further comprises a second squealer rib,
wherein the first squealer rib is disposed on a suction side of the turbine rotor blade,
wherein the second squealer rib is disposed on a pressure side of the turbine rotor blade, and
wherein the second squealer rib is disposed at a distance from the first squealer rib.

4. The turbine rotor blade according to claim 3 ,
wherein the ridge is a first ridge, the clearance is a first clearance, the local minimum value is a first local minimum value, and the narrowing surface is a first narrowing surface,
wherein the second squealer rib has a second ridge extending in an extending direction of the second squealer rib,
wherein the turbine rotor blade is configured to provide a second clearance between the tip surface of the turbine rotor blade and the inner wall surface of the casing of the turbine such that the second clearance has a second local minimum value on the second ridge,
wherein the second squealer rib has a second narrowing surface between the second ridge and a pressure-side edge of the second squealer rib on a pressure side of the second squealer rib,
wherein the second ridge is closer to a suction side of the second squealer rib than the pressure-side edge of the second squealer rib,
wherein the second ridge is at an intersection between the second narrowing surface and the suction side of the second squealer rib, and
wherein a slope of the second narrowing surface is constant over an entire length of the second narrowing surface from the pressure-side edge of the second squealer rib toward the second ridge such that the second narrowing surface is configured to monotonically reduce the second clearance from the second ridge toward the pressure-side edge of the second squealer rib.

5. The turbine rotor blade according to claim 4 ,
wherein the first narrowing surface is disposed over a wider range in a blade height direction of the turbine rotor blade than the second narrowing surface.

6. The turbine rotor blade according to claim 5 ,
wherein the first narrowing surface and the second narrowing surface are configured to be inclined from the inner wall surface of the casing of the turbine, and
wherein the first narrowing surface has a greater inclination angle than the second narrowing surface with respect to the inner wall surface of the casing of the turbine.

7. The turbine rotor blade according to claim 4 ,
wherein the first narrowing surface and the second narrowing surface are configured to be inclined from the inner wall surface of the casing of the turbine, and
wherein the first narrowing surface is on a same plane as the second narrowing surface.

8. The turbine rotor blade according to claim 1 ,
wherein the squealer rib has a chamfered edge portion including the ridge.

9. The turbine rotor blade according to claim 1 ,
wherein the turbine is a gas turbine.

10. A gas turbine, comprising:
a turbine including a rotor shaft having the turbine rotor blade according to claim 9 mounted to the rotor shaft in a circumferential direction, and a turbine casing housing the rotor shaft;
a combustor for supplying combustion gas to a combustion gas passage accommodating the turbine rotor blade; and
a compressor configured to be driven by the turbine and produce compressed air to be supplied to the combustor,
wherein the combustor is inside the turbine casing.

11. The turbine rotor blade according to claim 1 ,
wherein the squealer rib is disposed at least partially along an outer periphery of the airfoil portion on the tip surface of the turbine rotor blade.

12. The turbine rotor blade according to claim 3 ,
wherein the first local minimum value is equal to the second local minimum value.

Assignees

• Mitsubishi Heavy Ind Ltd

Inventors

• Nishimura Kazuya
• Fujimura Daigo
• Ito Eisaku
• Ishizaka Koichi

Classifications

• F05D2250/192

  bevelled · CPC title

• F02C7/28

  Arrangement of seals · CPC title

• F01D11/12

  using a rubstrip, e.g. erodible. deformable or resiliently-biased part · CPC title

• F01D5/20 Primary

  Specially-shaped blade tips to seal space between tips and stator {(F01D5/225 takes precedence)} · CPC title

• F05D2240/307

  related to the tip of a rotor blade · CPC title