U.S. patent application number 11/178282 was filed with the patent office on 2006-12-28 for grommeted bypass duct penetration.
This patent application is currently assigned to Pratt & Whitney Canada Corp.. Invention is credited to Vittorio Bruno, Goll Hadi, Bryan Olver.
Application Number | 20060288687 11/178282 |
Document ID | / |
Family ID | 32506863 |
Filed Date | 2006-12-28 |
United States Patent
Application |
20060288687 |
Kind Code |
A1 |
Bruno; Vittorio ; et
al. |
December 28, 2006 |
Grommeted bypass duct penetration
Abstract
A bypass duct sealing grommet, for sealing between an opening in
a gas turbine engine bypass duct wall and an external surface of a
projection extending through the opening, where the grommet has an
annular body with a central aperture having an internal periphery
adapted to sealingly engage the external surface of the projection.
A first flange and a second flange define an external slot about an
exterior periphery of the body adapted to receive and seal the
bypass duct wall between the flanges.
Inventors: |
Bruno; Vittorio;
(Mississauga, CA) ; Hadi; Goll; (Mississauga,
CA) ; Olver; Bryan; (Nobleton, CA) |
Correspondence
Address: |
OGILVY RENAULT LLP (PWC)
1981 MCGILL COLLEGE AVENUE
SUITE 1600
MONTREAL
QC
H3A 2Y3
CA
|
Assignee: |
Pratt & Whitney Canada
Corp.
|
Family ID: |
32506863 |
Appl. No.: |
11/178282 |
Filed: |
December 8, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10320411 |
Dec 17, 2002 |
6942452 |
|
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11178282 |
Dec 8, 2005 |
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Current U.S.
Class: |
60/226.1 |
Current CPC
Class: |
F01D 9/065 20130101;
Y10T 16/063 20150115; F01D 11/005 20130101; F05D 2230/642
20130101 |
Class at
Publication: |
060/226.1 |
International
Class: |
F02K 3/04 20060101
F02K003/04 |
Claims
1. (canceled)
2. (canceled)
3. (canceled)
4. (canceled)
5. (canceled)
6. (canceled)
7. (canceled)
8. (canceled)
9. (canceled)
10. (canceled)
11. (canceled)
12. (canceled)
13. (canceled)
14. (canceled)
15. (canceled)
16. (canceled)
17. (canceled)
18. A turbofan engine comprising: an annular bypass duct wall
having a generally circular opening defined therein by a peripheral
edge; a projection extending generally perpendicularly through the
opening, the projection having an external surface; an annular body
sealingly engaging the bypass duct wall peripheral edge along an
external periphery of the body and sealingly engaging the
projection external surface along an internal periphery of the
body, the body resiliently connecting the bypass duct wall and the
projection to provide a seal preventing air passing through the
opening in response to an air pressure differential thereacross,
said resilient connection adapted to permit relative movement
between the bypass duct wall and the projection while maintaining
said seal.
19. The turbofan engine of claim 18, wherein said permitted
relative movement is directed substantially normal to the
opening.
20. The turbofan engine of claim 18, wherein said permitted
relative movement is due to a change in a relative angle between
the bypass duct wall and the projection.
21. The turbofan engine of claim 18, wherein said permitted
relative movement is directed substantially parallel to a
longitudinal axis of the bypass duct.
22. The turbofan engine of claim 18, wherein the resilient
connection by reason of its shape and composition provides a
variation in resistance to said relative movement.
23. The turbofan engine of claim 18, wherein the body comprises a
flexible portion engaging the bypass duct wall and a less flexible
portion engaging the projection external surface.
24. The turbofan engine of claim 23, wherein said variation in
flexibility is caused by said portion of the body engaging the
projection external surface being relatively thicker than said
portion engaging the bypass duct wall.
25. The turbofan engine of claim 24, wherein the body has a
thickness which transitions smoothly from said portion of the body
engaging the projection external surface to said portion engaging
the bypass duct wall.
26. The turbofan engine of claim 18, wherein an inner portion of
the body provides said engagement with the projection external
surface, the portion adapted by its shape and composition to
improve a sealing effectiveness of said engagement in response to
said relative movement.
27. The turbofan engine of claim 19, wherein an inner portion of
the body provides said engagement with the projection external
surface, the portion adapted by its shape and composition to
improve a sealing effectiveness of said engagement in response to
said relative movement.
28. The turbofan engine of claim 20, wherein an inner portion of
the body provides said engagement with the projection external
surface, the portion adapted by its shape and composition to
improve a sealing effectiveness of said engagement in response to
said relative movement.
29. The turbofan engine of claim 18, wherein the bypass duct wall
peripheral edge is engaged between spaced-apart opposed portions of
the body defining a continuous slot.
Description
RELATED APPLICATION
[0001] This application is a continuation of U.S. application Ser.
No. 10/320,411 filed Dec. 17, 2002, now U.S. Pat. No. 6,942,452
issued Sep. 13, 2005.
TECHNICAL FIELD
[0002] The invention relates to a thin-walled duct penetration
sealing grommet, particularly useful for sealing between an opening
in a gas turbine engine bypass duct wall and the external surface
of a projection extending through the opening to simplify
manufacture by eliminating complex joint configurations, while
accommodating pressure differential, and relative thermal expansion
and contraction.
BACKGROUND OF THE ART
[0003] The bypass duct of a turbofan gas turbine engine contains a
pressurized flow of air between the outer duct wall and the engine
core. At several locations along the length and about the
circumference of the annular bypass duct, penetrations are
necessary for conveying fuel, oil, control cables or compressed air
bleed from the compressor to an aircraft cabin, as well as many
control and monitoring penetrations for instrumentation, inspection
and maintenance.
[0004] In the prior art, penetrations through the bypass duct are
generally accomplished by shrouding the conduits or cables in a
transverse sheet metal projection that may be contoured for
improved aerodynamic properties. The intersection between the
transverse sheet metal projection and the sheet metal walls of the
bypass duct are generally manufactured with a flange that is
riveted or welded to the relatively thin sheet metal bypass duct
walls. Such connections however must also accommodate the
difference in pressure between the pressurized flow of air through
the bypass duct and the ambient air surrounding the exterior of the
engine. Further, the engine core and the associated inner bypass
duct wall are exposed to significant heat and thermal expansion and
contraction relative to the less exposed outer bypass wall. As a
result, relative thermal expansion and contraction is also
accommodated by the connection between the projection and the outer
bypass wall or the inner bypass wall depending on the particular
arrangement.
[0005] As a result of the pressure differential and need to
accommodate relative thermal expansion and contraction, the sealing
and mechanical connection between projections through the bypass
wall and the relatively thin bypass duct walls is a relatively
complex arrangement requiring clearance for expansion and
contraction, resilient seals and quite often involves riveting a
structural support or containment flange to the relatively thin
bypass duct walls surrounding the opening for the penetration.
[0006] It is an object of the invention to provide a means to seal
between the opening and the gas turbine engine bypass duct wall and
the external surface of a projection extending through the opening
which accommodates relative thermal expansion and contraction and
pressure differential in a simple low cost manner.
[0007] Further objects of the invention will be apparent from
review of the disclosure, drawings and description of the invention
below.
DISCLOSURE OF THE INVENTION
[0008] The invention provides a bypass duct sealing grommet, for
sealing between an opening in a gas turbine engine bypass duct wall
and the external surface of a projection extending through the
opening. Conventionally, the intersection between the projection
and the sheet metal bypass duct requires accurate fitting and
welding, but cannot then accommodate thermal expansion and
contraction. The grommet enables an oversized opening for
accommodating relative thermal motion and simplifies manufacture.
The grommet has an annular body with a central aperture adapted to
seal against the external surface of the projection and two flanges
defining an external slot about an exterior periphery of the body
to contain and seal the bypass duct wall between the flanges.
DESCRIPTION OF THE DRAWINGS
[0009] In order that the invention may be readily understood, one
embodiment of the invention is illustrated by way of example in the
accompanying drawings.
[0010] FIG. 1 is an axial cross-sectional view through a typical
turbofan gas turbine engine showing the general arrangement of
internal components and in particular the numerous penetrations
through the outer annular bypass duct.
[0011] FIG. 2 is a radial cross-sectional view through the bypass
duct of FIG. 1.
[0012] FIG. 3 is a detailed axial cross-sectional view through a
prior art penetration through the bypass duct shown along the line
3-3 of FIG. 2.
[0013] FIG. 4 is an axial cross-sectional view along the line 4-4
of FIG. 2 showing another example of the prior art penetration
through the bypass duct wall.
[0014] FIG. 5 is a partially cut away perspective view of a
penetration through the bypass duct wall with a connecting grommet
in accordance with the invention.
[0015] FIG. 6 is a detailed cross-sectional view through a sealing
grommet and adjoining sheet metal walls of the bypass duct and
projecting penetration showing the symmetrical trapezoidal
cross-sectional profile of the grommet when the bypass wall and a
wall of the projection are in a perpendicular orientation.
[0016] FIG. 7 shows the deformations of the grommet to accommodate
an acute angular orientation.
[0017] FIG. 8 shows the deformation of the grommet when relative
radial motion is encountered between the bypass wall and a wall of
the projection as a result of internal pressure or thermal
expansion for example.
[0018] Further details of the invention and its advantages will be
apparent from the detailed description included below.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0019] FIG. 1 shows an axial cross-section through a turbofan gas
turbine engine. It will be understood however that the invention is
also applicable to any type of engine with a thin-walled air duct
with a penetration(s) requiring sealing. Air intake into the engine
passes over fan blades 1 in a fan case 2 and is then split into an
outer annular flow through the bypass duct 3 and an inner flow
through the low-pressure axial compressor 4 and high-pressure
centrifugal compressor 5. Compressed air exits the compressor 5
through a diffuser 6 and is contained within a plenum 7 that
surrounds the combustor 8. Fuel is supplied to the combustor 8
through fuel tubes 9 which is mixed with air from the plenum 7 when
sprayed through nozzles into the combustor 8 as a fuel air mixture
that is ignited. A portion of the compressed air within the plenum
7 is admitted into the combustor 8 through orifices in the side
walls to create a cooling air curtain along the combustor walls or
is used for cooling to eventually mix with the hot gases from the
combustor and pass over the nozzle guide vane 10 and turbines 11
before exiting the tail of the engine as exhaust.
[0020] FIG. 1 illustrates numerous projections and penetrations
through the bypass duct 3. Penetrations project through relatively
thin sheet metal inner bypass wall 12 and sheet metal or fiber
composite outer bypass wall 13. While the accessory gear box 14 has
a relatively rigid metal casing that extends through the bypass
duct 3, smaller penetrations or projections are also required such
as the compressed air bleed valve 15, penetrations for fuel supply
lines 16, lubricating oil supply line 17 and igniter 18.
[0021] FIG. 2 is a radial cross-sectional view on line 2-2 of FIG.
1 showing five penetrating projections 19 extending between the
inner bypass wall 12 and outer bypass wall 13 for internally
housing various conduits and other services extending between the
exterior surface of the engine and the central engine core.
[0022] FIG. 3 shows an example axial cross-sectional detail view
through a conventional prior art projection 19 having an outer
flange 20 mounted to the outer bypass wall 13 with a resilient
gasket 21. The projection 19 includes an internal end wall 22 fixed
with bolts 23 to the inner bypass wall 12. It will be appreciated
that the bypass duct 3 contains an annular flow of fast moving
pressurized air which is sealed from the ambient external air with
the gasket 21. Further the relative positions of the inner bypass
wall 12 and outer bypass wall 13 vary due to relative thermal
expansion and contraction, as well as flexural deflection due to
air pressure differential between the bypass duct 3 and ambient
external air. In the prior art therefore, the gasket 21
accommodates radial movements and seals the duct 3. The outer
bypass wall 13 includes an oversized opening 24 in the thin wall 13
which is reinforced and surrounded by an angle flange 25 riveted to
the outer bypass duct wall 13. The angle flange 25 retains the
gasket 21 and structurally reinforces the bypass duct wall 13 which
is weakened as a result of the opening 24. The opening 24 is
oversized in order to accommodate an assembly tolerance in
manufacturing and also to accommodate relative movement due to
pressure differential, and thermal expansion and contraction
between the projection 19 and the outer bypass duct wall 13.
[0023] Another example of prior art projection 19 is shown in FIG.
4 which has an end wall 22 secured with bolts 23 to a receiving
flange in the inner bypass duct 12. To accommodate relative
expansion and contraction between the inner bypass wall 12 and
outer bypass wall 13, bellows 26 extend between a flange 20 of the
projection 19 and a mounting plate 27 that is bolted to a
supporting plates and riveted to the relatively thin outer bypass
duct wall 13.
[0024] As is apparent from the details of FIGS. 3 and 4 and
explanation above, the need to accommodate relative thermal
expansion and contraction between the inner bypass duct wall 12 and
outer bypass duct wall 13, and to accommodate the pressure
differential between the bypass duct 3 and outer ambient air, has
resulted in relatively complex structures in the prior art that
require accurate fitting, gaskets, bellows and numerous fasteners,
rivets and reinforcing flanges.
[0025] FIG. 5 is a partially cut away perspective view of a bypass
duct sealing grommet 28 that provides a simple low cost means to
seal between an opening 24 in the gas turbine engine outer bypass
duct wall 13 and the external surface of the projection 19 which
extends through the opening 24. FIG. 6 shows a detailed sectional
view through the sealing grommet 28 which comprises an annular body
with a central aperture having an interior peripheral surface 29
that is adapted to seal against the external surface of the
projection 19.
[0026] As shown in FIG. 6, a first flange 30 and a second flange 31
define an external slot 32 which extends completely about the
exterior periphery of the grommet annular body and is adapted to
receive and seal the relatively thin bypass duct wall 13 between
the flanges 30 and 31. For simplicity in FIGS. 6, 7 and 8 the
bypass duct wall 13 is shown as a planar member however it will be
appreciated from viewing FIGS. 1 and 2 that the bypass duct wall 13
actually has a radial curvature and an axial curvature which
requires that the grommet 28 has the capacity to deform while
maintaining the ability to seal and resist the forces caused by
pressure differential on opposing sides of the bypass duct wall 13.
The grommet 28 must adapt to changes in the orientation of the wall
13 relative to the projection 19 due to the complex curvature of
the wall 13 while permitting a degree of relative thermal expansion
and contraction and further permitting a degree of manufacturing
tolerance in fitting and sealing between the wall 13 and projection
19.
[0027] FIG. 7 shows the manner in which the grommet 28 can be
deformed to accommodate an angular orientation indicated by angle
".alpha." whereas FIG. 8 illustrates distortion of the grommet 28
to accommodate radial motion of the bypass duct wall 13 relative to
the projection 19 which may be caused by pressure differential or
expansion and contraction for example.
[0028] In order to ensure that installation of the grommet 28 is
not inadvertently reversed, preferably the annular body of the
grommet 28 has a uniform or consistent cross-sectional profile
symmetric about the slot 32. As a result, during installation the
grommet 28 cannot be installed upside down since the preferred
cross-sectional profile is symmetric about the slot 32. As will be
appreciated by those skilled in the art, the grommet 28 may be
molded of silicon in an injection molding process or may be
extruded as a silicon strip to create an elongate sealing strip of
uniform or consistent cross-sectional profile. The elongate sealing
strip of which the grommet 28 is formed, is produced by extrusion
which is known to those skilled in the art. As a result the
cross-section does not vary along the length of the sealing strip
or the grommet 28 when installed. During installation, a first end
of the elongate sealing strip and a mating second end of the strip
abut at a joint which may be secured with adhesives or heat
resistant silicon caulking if necessary.
[0029] As shown in FIGS. 6, 7 and 8, preferably, the uniform,
consistent molded or extruded cross-sectional profile of the
grommet annular body 28 is trapezoidal with a relatively thick
collar 33 about the periphery of the projection 19 connecting the
first and second flanges 30 and 31. The flanges 30 and 31 have a
tapered profile which together with the collar 33 provides a
variation in resistance to distortion or bending between the
relatively flexible outer tip of the flanges 30 and 31 and the
stiffer abutting interior peripheral surface 29 which seals against
the projection 19. As seen in FIGS. 7 and 8, the trapezoidal
profile and use of the collar 33 increases the tendency of the
grommet 28 to jam and interfere with relative movement between the
outer bypass duct wall 13 and the projection 19. Jamming or
distortion creates a resilient or biasing force between the
interior peripheral surface 29 and the surface of the projection 19
without the need for embedded springs in the grommet 28. As a
result, the seal created by the distorted grommet 28 maintains the
pressure differential between opposite surfaces of the outer bypass
duct wall 13 while distortion of the grommet 28 permits a degree of
relative movement to accommodate thermal expansion and contraction
as well as to accommodate variation in the curvature of the outer
bypass duct wall 13 and its angular orientation relative to the
projection 19.
[0030] As in the prior art, the opening 24 which permits the
passage of the projection 19 through the outer bypass wall 13 is
oversized in order to permit manufacturing and assembly tolerance
and to accommodate relative thermal expansion or contraction or
distortion as a result of pressure differential.
[0031] With reference to FIGS. 5, 6, 7 and 8, the collar 33,
flanges 30 and 31 and opening 24 in the bypass duct wall 13 define
an annular clearance gap 34 therebetween. The clearance gap 34, as
seen in FIG. 6, permits use of an oversized hole 24 with an
acceptable assembly and manufacturing tolerance and ability to
accommodate relative movement between the bypass duct wall 13 and
the projection 19.
[0032] As seen in FIGS. 7 and 8 however the clearance gap 34 also
permits resilient distortion of the slot 32 and adjacent flanges 30
and 31 to improve the capacity of the grommet 28 to accommodate
movement and orientation of the outer bypass duct 13 relative to
the projection 19. Therefore, comparing the relatively complex
arrangements required by the prior art as illustrated in FIG. 3, in
particular compared to the use of the bypass duct sealing grommet
28 as illustrated in FIG. 5, significant savings in assembly cost
and simplicity of manufacture are achieved.
[0033] Although the above description relates to a specific
preferred embodiment as presently contemplated by the inventors, it
will be understood that the invention in its broad aspect includes
mechanical and functional equivalents of the elements described
herein.
* * * * *