Turbine bucket for use in gas turbine engines and methods for fabricating the same

• US 8,740,571 B2
• Filed: 03/07/2011
• Issued: 06/03/2014
• Est. Priority Date: 03/07/2011
• Status: Active Grant

• Current Assignee: GE Infrastructure Technology, LLC (General Electric Company)
• Original Assignee: General Electric Company
• Inventors: Garcia-Crespo, Andres
• Primary Examiner(s): Look, Edward
• Assistant Examiner(s): Christensen, Danielle M
• Application Number:
  US13/042,034
• Publication Number:
  US 20130108438A1
• Time in Patent Office: 1,184 Days
• Field of Search: 415/173.1, 416/224, 416/228, 416/229.R, 416/230, 416/229.A, 416/241.B, 298/897.1
• US Class Current: 416/230
• CPC Class Codes: F01D 1/00 Non-positive-displacement machines or engines, e.g. steam turbines wit working-fluid flows in opposite axial directions for balancing axial thrust F01D3/02; with other than pure rotation F01D23/00; turbines characterised by their use in special steam systems, cycles, or processes, regulating devices therefor F01K
• CPC Class Codes: F01D 5/147 Construction, i.e. structural features, e.g. of weight-saving hollow blades F01D5/148, F01D5/16 and F01D5/20 take precedence; blade shape F01D5/141; blades with cooling or heating channels or cavities F01D5/18; heating, heat-insulating or cooling means on blades F01D5/18
• CPC Class Codes: F01D 5/20 Specially-shaped blade tips to seal space between tips and stator F01D5/225 takes precedence
• CPC Class Codes: F01D 5/282 Selecting composite materials, e.g. blades with reinforcing filaments
• CPC Class Codes: F01D 5/284 Selection of ceramic materials
• CPC Class Codes: F01D 5/30 Fixing blades to rotors; Blade roots ; Blade spacers
• CPC Class Codes: F05D 2300/6033 Ceramic matrix composites [CMC]
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft
• CPC Class Codes: Y10T 29/49234 Rotary or radial engine making
• CPC Class Codes: Y10T 29/49336 Blade making
• CPC Class Codes: Y10T 29/49337 Composite blade

Abstract

A turbine bucket for use with a turbine engine. The turbine bucket includes an airfoil that extends between a root end and a tip end. The airfoil includes an outer wall that defines a cavity that extends from the root end to the tip end. The outer wall includes a first ceramic matrix composite (CMC) substrate that extends a first distance from the root end to the tip end. An inner wall is positioned within the cavity. The inner wall includes a second CMC substrate that extends a second distance from the root end towards the tip end that is different than the first distance.

Claims

1. A turbine bucket for use with a turbine engine, said turbine bucket comprising:

an airfoil extending between a root end and a tip end, said airfoil comprising;

an outer wall defining a cavity extending from said root end to said tip end, said outer wall comprising a first ceramic matrix composite (CMC) substrate extending a first distance from said root end to said tip end; and

an inner wall positioned within said cavity, said inner wall comprising a second CMC substrate extending a second distance from said root end towards said tip end that is different than said first distance,

wherein said first distance is greater than said second distance such that a tip pocket is defined at said tip end to facilitate reducing a flow of air across said tip end.

2. The turbine bucket in accordance with claim 1, wherein said inner wall comprises an outer surface positioned at the second distance, said outer wall comprises an inner surface, said tip pocket defined between said inner surface and said outer surface.

3. The turbine bucket in accordance with claim 2, wherein said outer wall includes a pressure side and an opposite suction side, said pressure side and said suction side extending between a leading edge and a trailing edge, said outer surface of said inner wall extends continuously between said pressure side and said suction side.

4. The turbine bucket in accordance with claim 3, wherein said inner surface of said outer wall defines said tip pocket having a substantially airfoil shape.

5. The turbine bucket in accordance with claim 2, wherein said inner wall comprises an inner surface that defines a interior chamber that extends between said inner surface and said root end.

6. The turbine bucket in accordance with claim 1, wherein said inner wall has a thickness greater than a thickness of said outer wall.

7. The turbine bucket in accordance with claim 1, wherein said outer wall comprises an inner surface defining an opening at each of said root end and said tip end.

8. A turbine engine system comprising:

a compressor;

a turbine coupled in flow communication with said compressor to receive at least some of the air discharged by said compressor;

a rotor shaft rotatably coupled to said turbine, said rotor shaft defining a centerline axis; and

a plurality of circumferentially-spaced turbine buckets coupled to said rotor shaft, each of said plurality of turbine buckets comprising;

an airfoil extending between a root end and a tip end, said airfoil comprising;

an outer wall defining a cavity extending from said root end to said tip end, said outer wall comprising a first ceramic matrix composite (CMC) substrate extending a first distance from said root end to said tip end; and

an inner wall positioned within said cavity, said inner wall comprising a second CMC substrate extending a second distance from said root end towards said tip end that is different than said first distance,

wherein said first distance is greater than said second distance such that a tip pocket is defined at said tip end to facilitate reducing a flow of air across said tip end.

9. The turbine engine system in accordance with claim 8, wherein said inner wall comprises an outer surface positioned at the second distance, said outer wall comprises an inner surface, said tip pocket defined between said inner surface and said outer surface.

10. The turbine engine system in accordance with claim 9, wherein said outer wall includes a pressure side and an opposite suction side, said pressure side and said suction side extending between a leading edge and a trailing edge, said outer surface of said inner wall extends continuously between said pressure side and said suction side.

11. The turbine engine system in accordance with claim 10, wherein said inner surface of said outer wall defines said tip pocket having a substantially airfoil shape.

12. The turbine engine system in accordance with claim 9, wherein said inner wall comprises an inner surface that defines an interior chamber that extends between said inner surface and said root end.

13. The turbine engine system in accordance with claim 8, wherein said inner wall has a thickness greater than a thickness of said outer wall.

14. The turbine engine system in accordance with claim 8, wherein said outer wall comprises an inner surface defining an opening at each of said root end and said tip end.

15. A method for fabricating a turbine bucket for use in a turbine engine system, said method comprising:

forming an outer wall of an airfoil that extends between a root end and a tip end, the airfoil including a dovetail region adjacent the root end, the outer wall including an inner surface that defines a cavity therein, wherein the cavity extends a first distance from the root end to the tip end;

forming an inner wall within the cavity, the inner wall extending a second distance from the root end towards the tip end that is different than the first distance and substantially beyond said dovetail region;

forming the outer wall from a first ceramic matric composite (CMC) and the inner wall from a second CMC different from the first CMC; and

forming a tip pocket at the tip end that is defined by the outer wall and the inner wall.

16. The method in accordance with claim 15, wherein the outer wall includes a plurality of sidewalls, said method further comprises depositing a plurality of first ceramic plies across a forming tool to form a first sidewall of the outer wall.

17. The method in accordance with claim 16, further comprising:

positioning a shaping tool at the tip end to facilitate forming the tip pocket; and

depositing a plurality of second ceramic plies across the first sidewall of the outer wall to form the inner wall.

18. The method in accordance with claim 17, further comprising:

depositing a plurality of third ceramic plies across the inner wall to form a second sidewall; and

coupling the second sidewall to the first sidewall to form the outer wall.