U.S. patent application number 12/349620 was filed with the patent office on 2009-05-07 for manufacturable and inspectable cooling microcircuits for blade-outer-air-seals.
This patent application is currently assigned to UNITED TECHNOLOGIES CORPORATION. Invention is credited to Frank Cunha, Edward F. Pietraszkiewicz, Om Parkash Sharma.
Application Number | 20090116956 12/349620 |
Document ID | / |
Family ID | 37527036 |
Filed Date | 2009-05-07 |
United States Patent
Application |
20090116956 |
Kind Code |
A1 |
Cunha; Frank ; et
al. |
May 7, 2009 |
MANUFACTURABLE AND INSPECTABLE COOLING MICROCIRCUITS FOR
BLADE-OUTER-AIR-SEALS
Abstract
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.
Inventors: |
Cunha; Frank; (Avon, CT)
; Sharma; Om Parkash; (South Windsor, CT) ;
Pietraszkiewicz; Edward F.; (Southington, CT) |
Correspondence
Address: |
BACHMAN & LAPOINTE, P.C. (P&W)
900 CHAPEL STREET, SUITE 1201
NEW HAVEN
CT
06510-2802
US
|
Assignee: |
UNITED TECHNOLOGIES
CORPORATION
Hartford
CT
|
Family ID: |
37527036 |
Appl. No.: |
12/349620 |
Filed: |
January 7, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11217702 |
Aug 31, 2005 |
|
|
|
12349620 |
|
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Current U.S.
Class: |
415/173.1 ;
29/889.721; 415/180 |
Current CPC
Class: |
B23P 15/00 20130101;
Y10T 29/4932 20150115; F05D 2230/211 20130101; F01D 11/24 20130101;
Y10T 29/49341 20150115; Y10T 29/49988 20150115 |
Class at
Publication: |
415/173.1 ;
415/180; 29/889.721 |
International
Class: |
F01D 11/08 20060101
F01D011/08; F01D 5/18 20060101 F01D005/18; B23P 15/04 20060101
B23P015/04 |
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.
Description
BACKGROUND OF THE INVENTION
[0001] (1) Field of the Invention
[0002] The present invention relates to a method for fabricating a
blade-outer-air-seal (BOAS) and to a BOAS manufactured thereby.
[0003] (2) Prior Art
[0004] 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).
[0005] 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 INVENTION
[0006] Accordingly, 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.
[0007] 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.
[0008] 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.
[0009] 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.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a cross sectional view showing the location of a
blade-outer-air-seal;
[0011] FIG. 2 illustrates a microcircuit core for cooling
passageways;
[0012] FIG. 3 illustrates a microcircuit manufacturing method with
a split line construction in accordance with the present invention;
and
[0013] FIG. 4 illustrates a transient liquid phase bonding
technique for joining sections of the blade-outer-air-seal
together.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0014] Referring now to the drawings, FIG. 1 illustrates a portion
of a gas turbine engine 10 showing the location of a
blade-outer-air-seal 12.
[0015] FIG. 2 illustrates a typical cooling microcircuit 50 which
may be used in the blade-outer-air seal 12. It should be recognized
that this microcircuit is merely exemplary and other types of
microcircuits can be used in the blade-outer-air-seal 12. The
microcircuit 50 has a leading edge microcircuit 52, a trailing edge
microcircuit 54, and side microcircuits 56 and 58. Each of the
microcircuits 52 has one or more cooling fluid inlets 60, a
plurality of passageways 62 formed by a plurality of internal
features 64, and a plurality of fluid outlets 66. The internal
features 64 may have any desired shape. For example, the internal
features 64 could be cylindrically shaped pedestals or oval shaped
pedestals. Different shaped internal features 64 could be used to
form the cooling passageways 62 for optimum cooling in a particular
microcircuit.
[0016] FIG. 3 illustrates the manner in which the cooling
microcircuit 50 is formed in a blade-outer-air-seal 12 in
accordance with the present invention. First, the
blade-outer-air-seal 12 is formed by two sections 70 and 72. The
sections 70 and 72 may be formed from any suitable material, such
as a nickel-based alloy, a cobalt-based alloy, an iron-based alloy,
or a titanium-based alloy, and are preferably cast, using any
suitable technique known in the art, in a manner that exposes the
respective internal walls 74 and 76. As can be seen from FIG. 3,
the two sections 70 and 72 may be separated along a split line 78.
The split line 78 may be formed so that it passes through the
middle of the microcircuit 50. In this case, a portion of the
microcircuit 50 may be formed on each of the internal walls 74 and
76. In a preferred embodiment, the split line 78 passes just above
the microcircuit 50. The location of the split line 78 is
determined by the stresses that would act across bonding surfaces.
Preferably, the split line 78 is placed where such stresses are
minimized.
[0017] 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.
[0018] 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.
[0019] Referring now to FIG. 4, in a final step, the
blade-outer-air-seal 10 is assembled along the split line 78 by
joining the sections 70 and 72 together using any suitable bonding
process known in the art. In a preferred embodiment, the bonding
process used to join the sections 70 and 72 together is a transient
liquid phase bonding process in which a mating surface interlayer
82 is created using foils 84 that deposit a thin film of an
interlayer of an alloying metal with a composition close to that of
the parent metal along with a melting point depressant. This thin
interlayer 82 with the parent blade pieces are bonded and heated
simultaneously causing a liquid interlayer. While at temperature,
rapid diffusion occurs. The resulting change in interlayer
composition causes isothermal solidification of the bond while at
temperature. Post bond heat treatment allows for further additional
diffusion resulting in a joint ideally equivalent, both
microstructurally and chemically, to the parent base metal. The
re-melt temperature of the bond line is comparable to the melting
point of the base blade material. Effectively, the bond region
mechanical properties approach those of the base blade material.
Since the resulting properties are reduced at the split line 78,
its location is placed where the operating stresses are minimized.
As previously mentioned, the BOAS segmentation is preferably placed
on a region where the stresses across the bonding surfaces are also
minimized.
[0020] As shown in FIG. 3, there is a ceramic core 90 which is
present during the casting of the sections 70 and 72. The ceramic
core may be removed, preferably by a chemical technique, after the
sections 70 and 72 have been joined.
[0021] While only one split line 78 has been illustrated, if
desired, the BOAS sections can be separated by a plurality of split
lines.
[0022] 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.
[0023] 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.
* * * * *