Shroud segment and assembly for a turbine engine

• US 20030185674A1
• Filed: 03/28/2002
• Published: 10/02/2003
• Est. Priority Date: 03/28/2002
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Fessler, Madeleine Elise, Noe, Mark Eugene, Darkins, Toby George Jr., Alford, Mary Ellen
• Granted Patent: US 6,733,235 B2
• Time in Patent Office: Days
• US Class Current: 415/173.1
• CPC Class Codes: F01D 11/08 for sealing space between rotor blade tips and stator specially-shaped blade tips therefor F01D5/20
• CPC Class Codes: F01D 25/246 Fastening of diaphragms or stator-rings
• CPC Class Codes: Y10T 29/49323 Assembling fluid flow directing devices, e.g., stators, diaphragms, nozzles

Abstract

A turbine engine shroud segment comprises a segment body including a radially inner surface arcuate at least circumferentially, a radially outer surface, and a plurality of axially and circumferentially spaced apart edge surfaces connected with and between the inner and outer surfaces. For carrying the segment body, the segment includes a projection, in one form a single projection, integral with and projecting generally radially outwardly from the body. The projection is selected to be positioned at a generally midway surface portion of the body radially outer surface between at least one of the plurality of spaced apart edge surfaces. The projection comprises a projection head spaced apart from the body radially outer surface and a projection transition portion, having a transition surface, integral with both the projection head and the body radially outer surface. The transition portion has a cross section smaller than the cross section of the projection head, at least in one of the axial and circumferential directions. In a turbine engine shroud assembly, a plurality of such shroud segments are assembled circumferentially with a shroud hanger that carries the segments in a hanger cavity. The cavity is defined at least in part by radially inner opposed hook members each including an end portion that registers with and carries the shroud segment at the projection transition surface.

Claims

1. A turbine engine shroud segment comprising a shroud segment body including a radially inner surface arcuate at least circumferentially, a radially outer surface, a first plurality of spaced apart axial edge surfaces connected with and between each of the inner and outer surfaces, and a second plurality of spaced apart circumferential edge surfaces connected with and between each of the inner and outer surfaces, wherein:

the shroud segment includes a shroud segment projection, for carrying the shroud segment body, integral with and projecting generally radially outwardly from the shroud segment body radially outer surface;

the projection being positioned on the shroud segment body radially outer surface at a generally midway surface portion between at least one of the first and second plurality of edge surfaces;

the projection comprising a projection head spaced apart from the shroud body radially outer surface, and a projection transition portion having a transition surface, the projection transition portion being integral with both the projection head and the shroud body radially outer surface, the transition portion being smaller in cross section than the projection head in at least one of the axial and circumferential directions.

2. The shroud segment of claim 1 in which the transition surface includes a planar portion.

3. The shroud segment of claim 1 in which:

the shroud segment includes a single projection; and

,

the single projection is at the generally midway surface portion of the shroud body radially outer surface spaced apart from the first plurality of axial edge surfaces and extends generally between the second plurality of circumferential edge surfaces.

4. The shroud segment of claim 3 in which:

the shroud segment is made of a low ductility material having a low tensile ductility, measured at room temperature to be no greater than about 1%; and

,

the projection transition portion is arcuate.

5. The shroud segment of claim 3 in which the projection is at a position at the generally midway surface portion closer to an axially aft of the first plurality of edge surfaces.

6. The shroud segment of claim 5 in which the position of the projection closer to the axially aft of the first plurality of edge surfaces is selected based on and substantially to reduce in the axial direction forces generated on the projection during operation of the turbine.

7. The shroud segment of claim 6 in which the position is selected substantially to balance in the axial direction forces generated on the projection during operation of the turbine.

8. The shroud segment of claim 6 in which:

the shroud segment is made of a ceramic matrix composite material having a tensile ductility measured at room temperature of no greater than about 1%; and

,

the projection transition portion is arcuate.

14. A turbine engine shroud assembly comprising:

a plurality of the turbine engine shroud segments of claim 1 assembled circumferentially to define a segmented turbine engine shroud; and

,

a shroud hanger carrying the shroud segments at each shroud segment projection;

the shroud hanger comprising a hanger radially inner surface defining a hanger cavity terminating in at least one pair of spaced apart radially inner hook members opposed one to the other;

each hook member including an end portion having an end portion inner surface defining a portion of the hanger cavity radially inner surface and shaped to cooperate in registry with and carry the shroud segment projection at the shroud segment projection transition surface.

15. The shroud assembly of claim 14 in which the end portion inner surface of each hook member includes a planar portion to register with a planar portion of shroud segment projection transition surface.

16. The shroud assembly of claim 14 in which the shroud hanger includes a shroud segment positioning member in contact with the shroud segment for positioning the shroud segment in at least one of the circumferential, radial and axial directions.

17. The shroud assembly of claim 16 in which the shroud segment positioning member is a pin through the shroud hanger preloaded toward the shroud segment.

18. The shroud assembly of claim 17 in which the shroud projection head includes a recess and the pin is disposed in the recess in contact with projection head.

19. The shroud assembly of claim 14 in which:

the shroud hanger includes axially spaced apart shroud segment stabilizing arms, each including a stabilizing arm end portion disposed toward and in juxtaposition with the shroud segment body radially outer surface generally at the spaced apart shroud body axial edge surfaces; and

,

a fluid seal is disposed between and in contact with each stabilizing arm end portion and the shroud segment body radially outer surface.

9. A method for making a turbine engine shroud segment comprising a shroud segment body including a radially inner surface arcuate at least circumferentially, a radially outer surface, a first plurality of spaced apart axial edge surfaces connected with and between each of the inner and outer surfaces, and a second plurality of spaced apart circumferential edge surfaces connected with and between each of the inner and outer surfaces,

the shroud segment including a shroud segment projection, for carrying the shroud segment body, integral with and projecting generally radially outwardly from the shroud segment body radially outer surface;

the projection being positioned on the shroud segment body radially outer surface at a generally midway surface portion between at least one of the first and second plurality of edge surfaces;

the projection comprising a projection head spaced apart from the shroud body radially outer surface, and a projection transition portion having a transition surface, the projection transition portion being integral with both the projection head and the shroud body radially outer surface, the transition portion being smaller in cross section than the projection head in at least one of the axial and circumferential directions comprising the steps of;

determining operating forces acting during engine operation on the shroud segment body as a result of a combination of temperature differential and pressure differential between an air cooled radially outer surface and the radially inner surface exposed to a flowstream of the turbine engine; and

,

selecting the position of the projection on the midway surface portion substantially to reduce the operating forces acting on the projection carrying the shroud segment body.

10. The method of claim 9 in which:

the shroud segment includes a single projection; and

,

the single projection is selected to be at the generally midway surface portion of the shroud body radially outer surface spaced apart from the first plurality of axial edge surfaces and extends generally between the second plurality of circumferential edge surfaces.

11. The method of claim 10 in which the projection is at a position at the generally midway surface portion closer to an axially aft of the first plurality of edge surfaces.

12. The method of claim 11 in which:

a low ductility material having a low tensile ductility, measured at room temperature to be no greater than about 1% is selected for the shroud segment; and

,

the projection transition portion is arcuate.

13. The method of claim 11 in which the position of the projection closer to the axially aft of the first plurality of edge surfaces is selected based on and substantially to reduce in the axial direction forces generated on the projection during operation of the turbine.