Transpiration cooled blade for a gas turbine engine

• US 4,314,794 A
• Filed: 10/25/1979
• Issued: 02/09/1982
• Est. Priority Date: 10/25/1979
• Status: Expired due to Term

• Current Assignee: Siemens Westinghouse Power Corporation
• Original Assignee: Westinghouse Electric Corporation (Paramount Global (f/k/a ViacomCBS Inc.))
• Inventors: Holden, executrix, by Joyce A., Holden, deceased, Abe N.
• Primary Examiner(s): Garrett, Robert E.
• Application Number:
  US06/088,245
• Time in Patent Office: 838 Days
• Field of Search: 416/97 A, 416/97 R, 416/225, 416/241 B, 415/115
• US Class Current: 416/97.00A
• CPC Class Codes: F01D 5/182 Transpiration cooling

Abstract

A transpiration cooled blade for a gas turbine engine is assembled from a plurality of individual airfoil-shaped hollow ceramic washers stacked upon a ceramic platform which in turn is seated on a metal root portion. The airfoil portion so formed is enclosed by a metal cap covering the outermost washer. A metal tie tube is welded to the cap and extends radially inwardly through the hollow airfoil portion and through aligned apertures in the platform and root portion to terminate in a threaded end disposed in a cavity within the root portion housing a tension nut for engagement thereby. The tie tube is hollow and provides flow communication for a coolant fluid directed through the root portion and into the hollow airfoil through apertures in the tube. The ceramic washers are made porous to the coolant fluid to cool the blade via transpiration cooling.

Claims

1. A blade for a gas turbine engine comprising:

a plurality of hollow ceramic washers having an airfoil cross-section and radially stacked upon each other to form the airfoil portion of the blade;

a metal cap covering the radially outermost washer and defining the blade tip;

a metal blade root defining a shank portion and rotor disc engaging projections;

a ceramic platform member interposed between the radially innermost washer and the blade root;

a perforated metal tie tube secured to said cap and extending generally radially therefrom through the airfoil portion and radially aligned apertures in the platform and shank portion is terminate within a cavity in said root portion to provide coolant flow communication from within said root to within said air-foil portion;

means within said cavity for tensioning said tie tube; and

wherein said ceramic washers include coolant flow channels extending therethrough for effusion of the coolant from within the airfoil portion to the external side thereof for transpiration cooling of said airfoil portion of the blade.

2. Structure according to claim 1 wherein the facing surfaces of adjacent ceramic washers are commonly inclined for indexed receipt of each adjacent washer.

3. Structure according to claim 2 wherein the end of the tie tube within said cavity in the root portion is externally threaded and said means for tensioning said tie tube comprises a tensioning nut engaging said threaded end.

4. Structure according to claim 3 wherein said cap defines an opening for exhausting a portion of the coolant at the blade tip for perfecting a sealing effect between the blade tip and adjacent stationary structure of the turbine.

5. Structure according to claim 1 wherein said coolant flow channels comprise grooves formed in the facing surfaces of adjacent ceramic washers.

6. Structure according to claim 1 wherein said coolant flow channels extending through said washers are randomly disposed.

7. A blade assembly for a gas turbine engine, said assembly comprising:

a metal root portion having an elongated shank defining a cavity therein subadjacent the radially outer surface with a first generally radially extending opening between said cavity and said surface;

a ceramic platform member seated on said radially outer surface and having a second opening generally concentric with said first opening;

a plurality of hollow ceramic airfoil-shaped washers, radially stacked upon each other to form the airfoil portion of said assembly, with the radially innermost washer seated on said platform member,

a metal cap covering the radially outermost washer and defining the blade tip;

a hollow metal tie tube attached to said cap and extending generally radially inwardly through said airfoil portion and said concentric openings and into said cavity to terminate therein in an externally threaded end; and

,

means within said cavity for tensioning said tie tube and placing a compressive force on said washers and platform; and

wherein,

said tie tube is in flow communication with a coolant fluid and includes apertures in that length within said airfoil portion for exhausting said fluid into said airfoil portion; and

wherein said washers define coolant flow channels for effusion of the coolant fluid from within the airfoil portion to the exterior thereof for transpiration cooling of the ceramic airfoil.

8. An assembly according to claim 7 wherein the facing surfaces of adjacent ceramic washers define complementary indexing configurations for indexed receipt of each adjacent washer.

9. Structure according to claim 7 wherein said coolant flow channels comprise grooves formed in the facing surfaces of adjacent ceramic washers.

10. Structure according to claim 7 wherein said coolant flow channels extend through said washers from within said airfoil portion to the exterior thereof in a random arrangement.