U.S. patent application number 14/758377 was filed with the patent office on 2015-11-26 for split cast vane fairing.
The applicant listed for this patent is UNITED TECHNOLOGIES CORPORATION. Invention is credited to Matthew Budnick, Conway Chuong, Jonathan Ariel Scott.
Application Number | 20150337687 14/758377 |
Document ID | / |
Family ID | 51021973 |
Filed Date | 2015-11-26 |
United States Patent
Application |
20150337687 |
Kind Code |
A1 |
Scott; Jonathan Ariel ; et
al. |
November 26, 2015 |
SPLIT CAST VANE FAIRING
Abstract
A turbine exhaust case (28) comprises a frame (102) and a
fairing (118). The frame has inner (106) and outer (104) rings
connected by a plurality of radial struts (108). The fairing
defines an airflow path within the frame, and has upstream (202)
and downstream (204) sections connected together about the radial
struts.
Inventors: |
Scott; Jonathan Ariel;
(Southington, CT) ; Budnick; Matthew; (Hudson,
NH) ; Chuong; Conway; (Manchester, CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
UNITED TECHNOLOGIES CORPORATION |
Hartford |
CT |
US |
|
|
Family ID: |
51021973 |
Appl. No.: |
14/758377 |
Filed: |
December 19, 2013 |
PCT Filed: |
December 19, 2013 |
PCT NO: |
PCT/US2013/076499 |
371 Date: |
June 29, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61747264 |
Dec 29, 2012 |
|
|
|
Current U.S.
Class: |
415/215.1 ;
29/889.2 |
Current CPC
Class: |
F01D 5/142 20130101;
F02C 7/20 20130101; Y02T 50/675 20130101; Y02T 50/60 20130101; F01D
25/30 20130101; Y10T 29/49321 20150115; F01D 5/14 20130101; F01D
25/10 20130101; Y02T 50/673 20130101; F01D 25/14 20130101; F01D
5/143 20130101; F01D 25/162 20130101; F01D 5/146 20130101; F01D
5/141 20130101; F01D 25/24 20130101; F05D 2230/232 20130101 |
International
Class: |
F01D 25/30 20060101
F01D025/30; F01D 25/24 20060101 F01D025/24 |
Claims
1. A turbine exhaust case comprising: a frame having inner and
outer rings connected by a plurality of radial struts; and a
fairing defining an airflow path within the frame, the fairing
comprising upstream and downstream sections connected together
about the radial struts.
2. The turbine exhaust case of claim 1, wherein the upstream and
downstream sections of the vane are welded together about the
radial struts along a cut line.
3. The turbine exhaust case of claim 2, wherein the cut line
defines a radial plane of separation between the upstream and
downstream sections.
4. The turbine exhaust case of claim 1, wherein the fairing
comprises radially inner and outer platforms connected by a vane
body.
5. The turbine exhaust case of claim 4, wherein the upstream and
downstream sections are connected along a chord near a
circumferentially thickest section of the vane body.
6. The turbine exhaust case of claim 5, wherein the chord is
located upstream of the circumferentially thickest section of the
vane body.
7. The turbine exhaust case of claim 1, wherein the fairing is
comprised of a plurality of joined-together angular segments.
8. The turbine exhaust case of claim 1, further comprising a
radiative heat shield disposed between the frame and the
fairing.
9. A method for assembling a turbine exhaust case, the method
comprising; casting a fairing with a vane body, an inner platform,
and an outer platform in a single piece; cutting the fairing into
an upstream section and a downstream section along a cut line;
assembling the upstream and downstream sections about a turbine
exhaust case frame; and attaching the upstream section to the
downstream section.
10. The method of claim 9, wherein the cut line is situated at a
chord location near the widest section of the vane body.
11. The method of claim 10, wherein the fairing includes a
sacrificial region to account for weld shrinkage and material
removed while cutting the fairing into upstream and downstream
sections.
12. The method of claim 10, wherein the vane is cut using electric
discharge machining.
13. The method of claim 10, wherein attaching the upstream section
to the downstream section comprises performing a weld long at the
chord location.
14. The method of claim 13, wherein the chord location is situated
upstream of the widest section of the vane body.
15. The method of claim 13, wherein the chord location is situated
downstream of the widest section of the vane body.
16. The method of claim 13, wherein the weld is a manual weld.
17. The method of claim 16, wherein the manual weld is performed
from forward of the fairing.
Description
BACKGROUND
[0001] The present disclosure relates generally to gas turbine
engines, and more particularly to a vane fairing for a turbine
exhaust case of an industrial gas turbine engine.
[0002] A turbine exhaust case is a structural frame that supports
engine bearing loads while providing a gas path at or near the aft
end of a gas turbine engine. Some aero engines utilize a turbine
exhaust case to help mount the gas turbine engine to an aircraft
airframe. In industrial applications, a turbine exhaust case is
more commonly used to couple gas turbine engines to a power turbine
that powers an electrical generator. Industrial turbine exhaust
cases may, for instance, be situated between a low pressure engine
turbine and a generator power turbine. A turbine exhaust case must
bear shaft loads from interior bearings, and must be capable of
sustained operation at high temperatures.
[0003] Turbine exhaust cases serve two primary purposes: airflow
channeling and structural support. Turbine exhaust cases typically
comprise structures with inner and outer rings connected by radial
struts. The struts and rings often define a core flow path from
fore to aft, while simultaneously mechanically supporting shaft
bearings situated axially inward of the inner ring. The components
of a turbine exhaust case are exposed to very high temperatures
along the core flow path. Various approaches and architectures have
been employed to handle these high temperatures. Some turbine
exhaust case frames utilize high-temperature, high-stress capable
materials to both define the core flow path and bear mechanical
loads. Other frame architectures separate these two functions,
pairing a structural frame for mechanical loads with a
high-temperature capable fairing to define the core flow path. In
systems with separate structural frames and flow path fairings, the
installation of the fairing on the frame without weakening either
component presents a technical challenge.
SUMMARY
[0004] The present disclosure is directed toward a turbine exhaust
case comprising a frame and a fairing. The frame has inner and
outer rings connected by a plurality of radial struts. The fairing
defines an airflow path within the frame, and has upstream and
downstream sections connected together about the radial struts.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a simplified partial cross-sectional view of an
embodiment of a gas turbine engine.
[0006] FIG. 2 is a cross-sectional view of a turbine exhaust case
of the gas turbine engine of FIG. 1.
[0007] FIG. 3A is a perspective view of an initial cast of a vane
fairing of the turbine exhaust case of FIG. 2.
[0008] FIG. 3B is a perspective view of the vane fairing of FIG.
3A, cut apart into upstream and downstream sections
[0009] FIG. 3C is a perspective view of the vane fairing of FIG.
3B, with the upstream and downstream sections attached together in
an assembled state
[0010] FIG. 4 is a method flowchart describing a method for
assembling the turbine exhaust case of FIG. 2.
DETAILED DESCRIPTION
[0011] FIG. 1 is a simplified partial cross-sectional view of gas
turbine engine 10, comprising inlet 12, compressor 14 (with low
pressure compressor 16 and high pressure compressor 18), combustor
20, engine turbine 22 (with high pressure turbine 24 and low
pressure turbine 26), turbine exhaust case 28, power turbine 30,
low pressure shaft 32, high pressure shaft 34, and power shaft 36.
Gas turbine engine 10 can, for instance, be an industrial power
turbine.
[0012] Low pressure shaft 32, high pressure shaft 34, and power
shaft 36 are situated along rotational axis A. In the depicted
embodiment, low pressure shaft 32 and high pressure shaft 34 are
arranged concentrically, while power shaft 36 is disposed axially
aft of low pressure shaft 32 and high pressure shaft 34. Low
pressure shaft 32 defines a low pressure spool including low
pressure compressor 16 and low pressure turbine 26. High pressure
shaft 34 analogously defines a high pressure spool including high
pressure compressor 18 and high pressure compressor 24. As is well
known in the art of gas turbines, airflow F is received at inlet
12, then pressurized by low pressure compressor 16 and high
pressure compressor 18. Fuel is injected at combustor 20, where the
resulting fuel-air mixture is ignited. Expanding combustion gasses
rotate high pressure turbine 24 and low pressure turbine 26,
thereby driving high and low pressure compressors 18 and 16 through
high pressure shaft 34 and low pressure shaft 32, respectively.
Although compressor 14 and engine turbine 22 are depicted as
two-spool components with high and low sections on separate shafts,
single spool or 3+ spool embodiments of compressor 14 and engine
turbine 22 are also possible. Turbine exhaust case 28 carries
airflow from low pressure turbine 26 to power turbine 30, where
this airflow drives power shaft 36. Power shaft 36 can, for
instance, drive an electrical generator, pump, mechanical gearbox,
or other accessory (not shown).
[0013] In addition to defining an airflow path from low pressure
turbine 26 to power turbine 30, turbine exhaust case 28 can support
one or more shaft loads. Turbine exhaust case 28 can, for instance,
support low pressure shaft 32 via bearing compartments (not shown)
disposed to communicate load from low pressure shaft 32 to a
structural frame of turbine exhaust case 28.
[0014] FIG. 2 is a cross-sectional view of an embodiment of turbine
exhaust case 28, illustrating frame 102 (with frame outer ring 104,
frame inner ring 106, frame struts 108, low pressure turbine
connection 110, and power turbine connection 112), bearing support
114, fasteners 116a and 116b, fairing 118 (with fairing outer
platform 120, fairing inner platform 122, and fairing vanes 124),
forward stiffening flange 126, aft stiffening flange 128, strut
heat shield 132, outer heat shield 134, and inner heat shield
136.
[0015] As described above with respect to FIG. 1, turbine exhaust
case 28 defines at least a portion of an airflow path for core flow
F, and carries load radially from bearing support 114 (which in
turn connects to bearing components, not shown). These two
functions are performed by separate components: frame 102 carries
bearing loads, while fairing 118 at least partially defines the
flow path of core flow F.
[0016] Frame 102 is a relatively thick, rigid support structure
formed, for example, of cast steel. Outer ring 104 of frame 102
serves as an attachment point for upstream and downstream
components at low pressure turbine connection 110 and power turbine
connection 112, respectively. Low pressure turbine connection 110
and power turbine connection 112 can, for instance, include
fastener holes for attachment to adjacent low pressure turbine 26
and power turbine 30, respectively. Frame inner ring 106 is
mechanically connected to bearing support 114 via fasteners 116a,
which can for instance be bolts, screws, pins or rivets. Frame
inner ring 106 communicates bearing load radially from bearing
support 114 to frame outer ring 104 via frame struts 108, which
extend at angular intervals between frame inner ring 106 and frame
outer ring 104. Although only one strut 108 is visible in FIG. 1,
turbine exhaust case 28 can include any desired number of struts
108.
[0017] Fairing 118 is a high-temperature capable aerodynamic
structure at least partially defining the boundaries of core flow F
through turbine exhaust case 28. Fairing outer platform 120
generally defines an outer flowpath diameter, while fairing inner
platform 122 generally defines an inner flowpath diameter. Fairing
vanes 124 surround frame struts 108, and form a plurality of
aerodynamic vane bodies. Fairing 118 can, for instance, be formed
of a superalloy material such as Inconel or other nickel-based
superalloy. Fairing 118 is generally rated for higher temperatures
than frame 102, and can be affixed to frame 102 via fasteners 116b.
In the depicted embodiment, fairing 118 is affixed to frame inner
ring 106 at the forward inner diameter of fairing 118, although
alternative embodiments of turbine exhaust case 28 can secure
fairing 118 by other means and/or in other locations. Forward and
aft stiffening flanges 126 and 128, respectively, can extend
radially outward from the entire circumference of fairing outer
platform 120 to provide increased structural rigidity to fairing
118.
[0018] Turbine exhaust case 28 includes a plurality of heat shields
to protect frame 102 from radiative and convective heating. Strut
heat shield 132 is situated between fairing vanes 124 and frame
struts 108. Outer heat shield 134 can be situated between fairing
outer platform 120 and frame outer ring 104. Inner heat shield 136
can be is situated radially inward of a forward portion of fairing
inner platform 122. Like fairing 118, all three heat shields 132,
134, and 136 can be formed of Inconel or a similar nickel-based
superalloy. Strut heat shield 132, outer heat shield 134, and inner
heat shield 136 act as barriers to heat from fairing 118, which can
become very hot during operation of gas turbine 10. Heat shields
132, 134, and 136 thus help to protect frame 102, which can be
rated to lower temperatures than fairing 118, from exposure to
excessive heat.
[0019] FIGS. 3A, 3B, and 3C present successive steps in the
formation and installation of fairing 118 with outer platform 120,
inner platform 122, and fairing vanes 124. FIGS. 3A, 3B, and 3C
illustrate a single angular section 200 of fairing 118. Angular
section 200 can be a representative section of a unitary fairing
cast as a annular piece, or one of several separately cast angular
pieces welded or otherwise joined together to form fairing 118.
Angular section 200 includes forward section 202 and aft section
204 separated by sacrificial region 206 situated along cut line
CL.
[0020] As shown in FIG. 3A, angular section 200 is initially cast
in a single piece. As shown in FIG. 3B, angular section 200 is cut
along cut line CL to separate forward section 202 from aft section
204, thereby allowing vane section 200 to be situated about frame
102. Fairing section 200 can, for instance, be cut by electric
discharge machining (EDM). The cutting process consumes a portion
of sacrificial region 206 of angular section 200, leaving reduced
forward and aft sacrificial regions 206a and 206b attached to
forward section 202 and aft section 204, respectively. In
alternative embodiments, forward and aft sections 202 and 204 can
be separated by other means, such as by mechanically cutting along
cut line CL. In some such embodiments, forward and aft sections 202
and 204 can subsequently be finished along cut line CL to smooth
the resulting cut. The width of sacrificial region 206 can be
scaled as appropriate to the method of cutting selected. Forward
and aft sections 202 and 204 are then positioned about strut 108 of
frame 102, and welded together along cut line CL as shown in FIG.
3C to form a single unitary piece. This weld consumes the remainder
of forward and aft sacrificial sections 206a and 206b.
[0021] The positioning of cut line CL is selected to distance the
resulting eventual weld apart from leading and trailing edges of
fairing vane 124 where stresses on fairing 118 from core airflow F
are greatest. In the depicted embodiment, cut line CL is situated
along a chord slightly upstream of the widest portion of fairing
vane 124. This positioning allows easy access from the forward side
of fairing 118 to perform a manual weld along cut line CL during
installation. In alternative embodiments wherein a manual weld is
performed from aft of fairing 118, cut line CL can instead be
positioned along a chord downstream of the widest portion of
fairing vane 124.
[0022] FIG. 4 illustrates the method set out above with respect to
FIGS. 3A, 3B, and 3C for installing fairing 118. First, frame 102
is produced in a single piece. (Step S1). Frame 102 can be formed
in a single unitary section, or formed from several separately cast
pieces joined together. Next, forward and aft sections 202 and 204
of fairing 118 are cast in a single angular piece 200. (Step S2).
As discussed above, fairing 118 can be formed from a plurality of
separate angular sections 200, or in a single annular piece.
Fairing 118 can, for instance, be die cast. Fairing 118 is then cut
into forward section 202 and aft section 204, thereby consuming a
portion of sacrificial region 206. (Step S3). Forward and aft
sections 202 and 204 are assembled about strut 108 of frame 102
(Step S4), and welded back together (Step S5), thereby consuming
the remainder of sacrificial region 206.
[0023] By splitting each angular section 200 into multiple sections
during its installation process, fairing 118 can be installed about
the strut of a unitary frame. Splitting fairing 118 into forward
and aft sections produces an assembled fairing without weak joints
corresponding to weld locations at leading or trailing edges of
fairing vanes 124.
Discussion of Possible Embodiments
[0024] The following are non-exclusive descriptions of possible
embodiments of the present invention.
[0025] A turbine exhaust case comprising a frame having inner and
outer rings connected by a plurality of radial struts, and a
fairing defining an airflow path within the frame. The fairing
comprises upstream and downstream sections connected together about
the radial struts.
[0026] The turbine exhaust case of the preceding paragraph can
optionally include, additionally and/or alternatively, any one or
more of the following features, configurations and/or additional
components:
[0027] wherein the upstream and downstream sections of the vane are
welded together about the radial struts along a cut line.
[0028] wherein the cut line defines a radial plane of separation
between the upstream and downstream sections.
[0029] wherein the fairing comprises radially inner and outer
platforms connected by a vane body.
[0030] wherein the upstream and downstream sections are connected
along a chord near a widest section of the vane body.
[0031] wherein the chord is located upstream of the widest section
of the vane body.
[0032] wherein the fairing is comprised of a plurality of
joined-together angular segments further comprising a radiative
heat shield disposed between the frame and the fairing.
[0033] A method for assembling a, the method comprising casting a
fairing with a vane body, an inner platform, and an outer platform
in a single piece; cutting the fairing into an upstream section and
a downstream section along a along a cut line; assembling the
upstream and downstream sections about a turbine exhaust case
frame; and attaching the upstream section to the downstream
section.
[0034] The method of the preceding paragraph can optionally
include, additionally and/or alternatively, any one or more of the
following features, configurations and/or additional
components:
[0035] wherein the cut line is situated along a chord near the
widest section of the vane body wherein the fairing includes a
sacrificial region to account for weld shrinkage and material
removed while cutting the fairing into upstream and downstream
sections.
[0036] wherein the vane is cut using electric discharge
machining.
[0037] wherein attaching the upstream section to the downstream
section comprises performing a weld long the chord.
[0038] wherein the chord is upstream of the widest section of the
vane body.
[0039] wherein the chord is downstream of the widest section of the
vane body.
[0040] wherein the weld is a manual weld.
[0041] wherein the manual weld is performed from forward of the
fairing.
[0042] While the invention has been described with reference to an
exemplary embodiment(s), it will be understood by those skilled in
the art that various changes can be made and equivalents can be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications can be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment(s) disclosed, but that the invention will
include all embodiments falling within the scope of the appended
claims.
* * * * *