MANUFACTURABLE AND INSPECTABLE COOLING MICROCIRCUITS FOR BLADE-OUTER-AIR-SEALS
A method for manufacturing a cooling microcircuit in a blade-outer-air-seal is provided. The method broadly comprises the steps of forming a first section of the blade-outer-air-seal having a first exposed internal wall, forming a second section of the blade-outer-air-seal having a second exposed internal wall, and forming at least one cooling microcircuit on at least one of the first and second exposed internal walls.
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(1) Field of the Invention
The present invention relates to a method for fabricating a blade-outer-air-seal (BOAS) and to a BOAS manufactured thereby.
(2) Prior Art
As of today, the enabling technology for cooling microcircuits relies upon, and is implemented by, refractory metal cores in a double wall design. The refractory metal cores have an elevated melting temperature, making it desirable for processing during investment casting before being leached out and forming the intricate microcircuit passageways within the blade wall (hence the term double wall design).
One of the difficulties in forming cooling microcircuits in this fashion is the lack of an easy way to access the microcircuits for inspection.
SUMMARY OF THE INVENTIONAccordingly, it is an aim of the present invention to provide a method for manufacturing cooling microcircuits in BOAS which lends itself towards facilitating inspection of the microcircuits that are formed.
In accordance with the present invention, a method for manufacturing cooling microcircuits in BOAS is provided. The method broadly comprises the steps of forming a first section of the blade-outer-air-seal having a first exposed internal wall, forming a second section of the blade-outer-air-seal having a second exposed internal wall, and forming at least one cooling microcircuit on at least one of the first and second exposed internal walls.
Further, in accordance with the present invention, a blade-outer-air-seal is provided. The blade-outer-air-seal broadly comprises a cast first section, a cast second section, at least one cooling microcircuit intermediate the first and second sections, and a mating surface interlayer between the first and second sections.
Other details of the manufacturable and inspectable cooling microcircuits for blade-outer-air-seals, as well as other objects and advantages attendant thereto, are set forth in the following detailed description and the accompanying drawings wherein like reference numerals depict like elements.
Referring now to the drawings,
The internal features 64 of the microcircuit 50 may be formed on one or both of the internal walls 74 and 76 using any suitable technique known in the art. For example, the internal features 64 may be manufactured from metal matrix composites using plasma spraying thickness build-up with pre-alloyed powder followed by surface finish control. Alternatively, the internal features 64 may be manufactured by a combination of hot-working, surface grinding, and chemical milling to final thickness. The fact that the internal walls 74 and 78 are totally exposed permits a search of an optimum cooling arrangement in terms of durability and manufacturing. This also allows the microcircuit 50 to be implemented in a single wall product.
When the microcircuit is formed only one of the walls 74 and 76, a cover plate 80 is placed over the microcircuit. The cover plate 80 may be formed from the same material as the blade-outer-air-seal or the same material as the internal features 64, or any other suitable material known in the art. The cover plate 80 may be bonded in place using any suitable bonding technique known in the art. Preferably, a solid state diffusion bonding process may be used to join the cover plate 80 to the internal features 64.
Referring now to
As shown in
While only one split line 78 has been illustrated, if desired, the BOAS sections can be separated by a plurality of split lines.
One of the principal advantages of the method of the present invention is the ease of manufacture of the BOAS and its internal cooling microcircuits. Another principal advantage is the ability to manufacture and inspect the internal cooling microcircuits prior to assembling the BOAS.
It is apparent that there has been provided in accordance with the present invention, a manufacturable and inspectable cooling microcircuit for a blade-outer-air-seal which fully satisfies the objects, means, and advantages set out hereinbefore. While the present invention has been described in the context of specific embodiments thereof, other unforeseen alternatives, modifications, and variations may become apparent to those skilled in the art having read the foregoing description. Accordingly, it is intended to embrace those alternatives, modifications, and variations as fall within the broad scope of the appended claims.
Claims
1-12. (canceled)
13. A blade-outer-air-seal consisting of:
- a cast first section;
- a cast second section;
- at least one cooling microcircuit intermediate said first and second sections; and
- a mating surface interlayer between said first and second sections.
14. The blade-outer-air-seal according to claim 13, wherein said at least one cooling microcircuit has a leading edge microcircuit and a trailing edge microcircuit.
15. The blade-outer-air-seal according to claim 14, wherein said at least one cooling microcircuit further has at least one side microcircuit which is independent of said leading edge microcircuit and said trailing edge microcircuit.
16. The blade-outer-air-seal according to claim 13, wherein said at least one cooling microcircuit is located on only one of said sections and includes a cover plate over said at least one cooling microcircuit.
17. The blade-outer-air-seal according to claim 16, wherein said at least one cooling microcircuit has a plurality of internal features and said cover plate is solid state diffusion bonded to said internal features.
18. The blade-outer-air-seal according to claim 15, wherein each of said microcircuits has at least one cooling fluid inlet, at least one outlet, and a plurality of passageways formed by a plurality of internal features.
19. The blade-outer-air-seal according to claim 13, wherein said interlayer comprises a bond region formed from an alloying metal with a composition close to that of a metal forming at least one of said first and second sections along with a melting point depressant.
20. A method for manufacturing a cooling microcircuit in a blade-outer-air-seal comprising the steps of:
- casting a first section of the blade-outer-air-seal having a first exposed internal wall;
- casting a second section of the blade-outer-air-seal having a second exposed internal wall;
- forming at least one cooling microcircuit on at least one of the first and second exposed internal walls;
- creating a mating interlayer by placing foils between said first section and said second section; and
- joining said first section and said second section together by heating said foils and the first and second sections.
21. A method according to claim 20, wherein the foils placing step comprises placing foils formed from a material having a composition close to a metal forming each of the first and second sections and having a melting point depressant.
22. A method according to claim 20, further comprising subjecting said blade-outer-air-seal to a post bond heat treatment.
Type: Application
Filed: Jan 7, 2009
Publication Date: May 7, 2009
Applicant: UNITED TECHNOLOGIES CORPORATION (Hartford, CT)
Inventors: Frank Cunha (Avon, CT), Om Parkash Sharma (South Windsor, CT), Edward F. Pietraszkiewicz (Southington, CT)
Application Number: 12/349,620
International Classification: F01D 11/08 (20060101); F01D 5/18 (20060101); B23P 15/04 (20060101);