Note: Descriptions are shown in the official language in which they were submitted.
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METHOD OF MANUFACTURING A FAIRING
WITH AN INTEGRATED SEAL
BACKGROUND OF THE INVENTION
This invention relates generally to seals for reducing leakage of a fluid, and
more specifically to integrated seals in fairings used in gas turbine engines
and
methods of manufacturing fairings having integrated seals.
In a gas turbine engine, air is pressurized in fan and compressor modules
during operation. The air is channeled through separate flow paths in the fan
module
and the compressor module. FIG. I illustrates, for example, a bypass airflow 2
in a fan
module and a core airflow 3 in a low pressure compressor (booster) module.
Compressed air is mixed with fuel in a combustor and ignited, generating hot
combustion gases which flow through turbine stages that extract energy
therefrom for
powering the fan and compressor rotors and generate engine thrust to propel an
aircraft in flight. Engine frames are used to support and carry the bearings
which, in
turn, rotatably support the rotors. Conventional turbofan engines have a fan
frame, a
mid-frame, and an aft turbine frame. Such frames may have an external casing
and an
internal hub which are attached to each other through a plurality of multiple
radially
extending struts that extend through the flowpath.
Flowpath liner and fairing assemblies provide a flowpath that guides and
directs the gases flowing through the frame. In some gas turbine engines, the
stator
assemblies have segmented fairings that are arranged circumferentially wherein
vanes
or struts extend between circumferentially adjacent fairing segments. A strut
or a vane
that extends radially through a flowpath is referred to herein as outlet guide
vane
("OGV"). The OGVs may, in some applications, reorient the flow in the flowpath
to a
more axial direction. FIG. 2 shows a conventional assembly of two conventional
fairings 30 adjacent to an OGV 22 that extends radially between them. The OGV
is
attached at its radially outer end using conventional attachment means, such
as, for
example, an attachment flange 27. The conventional fairings 30 are arranged
circumferentially to form an annular flow path such as, for example, the
bypass
flowpath that flows bypass airflow 2 shown in FIG. 1.
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FIG. 2 illustrates some of the problems that may exist in using conventional
stator assemblies 35 having the conventional fairings 30. The conventional
stator
assembly 35 has an axial gap 32 located at the interface between two adjacent
conventional fairings 30. An axial gap 34 also exists at the interface between
the OGV
22 and the two adjacent conventional fairings 30. These axial gaps 32, 34
cause
leakage of a portion of the fluid flowing over the conventional fairings 30,
such as the
leakage of bypass airflow 2 from the flowpath, leading to a performance loss
in the
engine. The performance loss is further aggravated by the fact that, in some
designs,
the OGVs may have different geometries at different circumferential locations
and
result in conventional fairings 30 having axial gaps 34 that vary at these
different
circumferential locations. In conventional methods of assembling the
conventional
stator assembly 35, the gaps 32, 34 are sometimes closed during assembly using
known methods, such as caulking using commercially available materials.
Because of
the additional assembly and coupling or sealing processes and hardware
associated
with these multi-piece conventional fairings 30 and OGV's, and because of the
tolerances that may be necessary to meet structural requirements,
manufacturing and
assembly costs of such conventional assembly and sealing methods using
conventional fairings 30 are high and time-consuming. Durability of the
conventional
sealing of the conventional fairings 30 described above may also be a problem
in
certain applications.
Accordingly, it would be desirable to have a fairing having a seal that is
capable of interfacing with an adjacent component, such as, for example,
another
fairing or an OGV, to facilitate reducing leakage of a fluid. It would be
desirable to
have a stator assembly that has fairings adjacent to a vane wherein the
fairings have
seals that engage with adjacent components to facilitate reducing leakage of a
fluid in
the stator assembly. It would be desirable to have a method of manufacturing
an
integrated seal on a component, such as for example, a fairing. It would be
desirable to
have a method of assembling a stator having fairings that have integrated
seals.
BRIEF DESCRIPTION OF THE INVENTION
The above-mentioned need or needs may be met by exemplary embodiments
which provide a method of manufacturing an integrated seal on a component,
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comprising the steps of supplying a component having an edge portion, forming
a
profile on the edge portion, supplying a seal, applying a bond preparation on
a surface
on the edge portion, applying a bonding material on the seal, mounting the
seal to the
edge portion, and curing the bond.
In another aspect of the present invention, a method of assembling a stator
assembly comprises the steps of providing a vane, providing a first fairing
located
near a first side of the vane, the first fairing having a first seal coupled
to a first edge
portion of the first fairing, providing a second fairing located near a second
side of the
vane, the second fairing having a second seal coupled to a second edge portion
of the
second fairing and engaging a portion of the first seal with a portion of the
second
seal.
BRIEF DESCRIPTION OF THE DRAWINGS
The subject matter which is regarded as the invention is particularly pointed
out and distinctly claimed in the concluding part of the specification. The
invention,
however, may be best understood by reference to the following description
taken in
conjunction with the accompanying drawing figures in which:
FIG. 1 is an axial sectional view through a portion of a gas turbine engine
having an exemplary embodiment of the present invention.
FIG. 2 is an isometric view of a conventional stator assembly using
conventional fairings.
FIG. 3 is a plan view of a stator assembly according to an exemplary
embodiment of the present invention.
FIG. 4 is an isometric view of a fairing according to an exemplary
embodiment of the present invention.
FIG. 5 is a frontal view of a portion of the fairing shown in FIG. 4.
FIG. 6 is a schematic cross-sectional view of two adjacent fairings according
to an exemplary embodiment of the present invention.
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FIG. 7 is a schematic cross-sectional view of two adjacent fairings according
to an alternative embodiment of the present invention.
FIG. 8 is a schematic cross-sectional view of two adjacent fairings according
to another alternative embodiment of the present invention.
FIG. 9 is a schematic cross-sectional view of two adjacent fairings according
to another alternative embodiment of the present invention.
FIG. 10 is a schematic cross-sectional view of two adjacent fairings
according to another alternative embodiment of the present invention.
FIG. 11 is a flow chart showing an exemplary embodiment of a method for
manufacturing an integrated seal.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings wherein identical reference numerals denote the
same elements throughout the various views, FIG. 1 shows a portion of a gas
turbine
engine, having a fan 5 and a booster (low pressure compressor) 7 configured
for
channeling and pressurizing a bypass airflow 2 and a core airflow 3
respectively. The
booster 7, which pressurizes the air flowing through the core, is
axisymmetrical about
a longitudinal centerline axis 15, and includes an inlet guide vane (IGV)
stage 11
having a plurality of inlet guide vanes 12 spaced in a circumferential
direction around
the longitudinal centerline axis 15 and a plurality of stator vane stages 17.
The booster
7 further includes multiple rotor stages 18 which have corresponding rotor
blades 50
extending radially outwardly from a rotor hub 19 or corresponding rotors in
the form
of separate disks, or integral blisks, or annular drums in any conventional
manner.
Cooperating with each rotor stage, such as for example, the rotor stage 18, is
a
corresponding stator stage 17. Each stator stage 17 in the booster 7 comprises
a
plurality of circumferentially spaced apart stator vanes 40.
The fan rotor 5 pressurizes the air coming into the engine inlet and comprises
a plurality of fan blades 6 arranged circumferentially around the longitudinal
centerline axis 15. The bypass air flow 2 passes through an annular bypass
duct 4 and
the fan frame struts or OGVs 22. The OGVs, in some applications, reorient the
flow in
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the flowpath to a more axial direction. The OGVs may also carry structural
loads in
some applications, whereas in other applications, the structural loads are
carried by the
frame struts and the OGVs are used for re-orienting flows.
FIG. 3 shows a stator assembly 80 according to an exemplary embodiment of
the present invention. The stator assembly 80 comprises a stator vane 22, a
first fairing
81 having a first seal 61 located circumferentially adjacent to a first side
25 of the
vane 22. A second fairing 82 having a second seal 62 is located
circumferentially
adjacent to a second side 26 side of the vane 22 as shown in FIG. 3. The first
seal 61
may be integrally coupled to a first edge portion 45 of the first fairing 81
and the
second seal 62 may be integrally coupled to a second edge portion 46 of the
second
fairing 82. The first fairing 81 is located circumferentially very close to
the vane 22
such that the first seal 61 reduces the axial gap between the first seal 61
and the first
side of vane 22. The first seal 61 may be brought into contact with the first
side 25 of
the vane 22 such that the axial gap between the first seal 61 and the first
side of vane
22 may be eliminated at those locations where such contact is established.
Similarly,
the second fairing 82 is located circumferentially very close to the vane 22
such that
the second seal 62 reduces the axial gap between the second seal 62 and the
second
side of vane 22. The second seal 62 may be brought into contact with the
second side
26 of the vane 22 such that the axial gap between the second seal 62 and the
second
side of vane 22 may be eliminated at those locations where such contact is
established.
By reducing, or even eliminating, the axial gaps between the vane 22 and the
adjacent
seals 61, 62, leakage of the air flowing in the stator assembly 80 through
such axial
gaps is reduced.
As shown in FIG. 3, the first fairing 81 and second fairing 82 are assembled
such that the first seal 61 and the second seal 62 also interface with each
other at axial
locations away from the vane 22. The first fairing 81 and second fairing 82
are
assembled such that at locations axially forward and axially aft from the vane
22, the
first seal 61 is circumferentially very close to the second seal 62 and reduce
the axial
gap between them. The axial gap may be eliminated at some axial locations
wherein
the first seal 61 overlaps with the second seal 62, such as, for example,
shown in FIG.
6 and explained subsequently herein. By reducing, or even eliminating, the
axial gaps
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between the adjacent seals 61, 62, leakage of the air flowing in the stator
assembly 80
through such axial gaps is reduced.
FIG. 4 shows a fairing 40 according to an exemplary embodiment of the
present invention. Fairing 40 may be used, preferably, as the first fairing 81
and/or the
second fairing 82 in the stator assembly 80 described previously herein in
detail.
Fairing 40 comprises a surface 42 which may serve to contain a fluid or as a
bounding
surface for a fluid that flows over the surface 42. For example, fairing 40
may be used
as one of the components that form a portion of conduit walls of the annular
flowpath
shown in FIG. 1 or a stator assembly 80. Surface 42 of the fairing 40 defines
a portion
of the flowpath 4 boundaries that bound an airflow, such as the bypass airflow
2
shown in FIG. 1 and the airflow through the stator assembly 80 having OGVs.
Fairing 40 comprises an edge portion 41 that has a geometry adapted to
receive a seal, such as seal 50 shown in FIG. 4. Two edge portions 41 that are
located
circumferentially apart from each other, and having seals 50 coupled to each
edge
portion 41, are illustrated in FIG. 4. A first seal 61 is located at the first
edge portion
45, and a second seal 62 is located at a second edge portion 46 of the fairing
40. The
edge portions of the fairing 40 have a geometric contour in the axial
direction that
generally corresponds with the geometry of the interface with vane 22. For
example,
as shown in FIG. 4, the first edge portion 45 has a generally convex geometry
in the
axial direction corresponding generally with a concave portion of the vane 22,
and the
second edge portion 46 has a generally concave geometry corresponding
generally
with a convex portion of the vane 22. Fairing 40 is made known from materials,
such
as nylon having about 20% carbon, using known processes, such as injection
molding.
Seals are preferably made from a Silicone material, such as Room Temperature
Vulcanized ("RTV") Silicone, that is commercially available. Other suitable
materials,
such as Silicone, Rubber, Neoprene, Polysulfide, and Polyurethane, or any
combinations thereof, may also be used to make the seals.
An enlarged view of an edge portion 41 of the fairing 40 having a seal 50
coupled to it is shown in FIG. 5. The edge portion 41 has an edge 44 that has
a
suitable contour in the axial direction, as explained previously. The edge
portion 41
has suitable bonding surfaces 43 that are used for bonding with the seal, as
explained
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subsequently herein. The seal 50 has a cross-sectional shape as shown, for
example, in
FIG. 5 and FIG. 6. The seal 50 comprises a support portion 59 and a head
portion 56,
see FIG. 5. The support portion 59 comprises a support flange 54 that supports
the
seal 50 on the edge portion 41 of the fairing 40. The support flange 54 may be
bonded
to a bonding surface 43 on the fairing 40, using bonding material 48 at the
interface
between the fairing 40 and the seal support flange 54, as explained
subsequently
herein. In the exemplary embodiment shown in FIG. 4 and 5 the seal 50 has two
support flanges 54, 55 that are used to mount the seal 50 to the edge portion
41 of the
fairing 40. The head portion 56 of the seal 50 comprises a sealing wall 57 and
a
support wall 58. The sealing wall 57 has a contact face 52 that, when
assembled in a
sealing arrangement (see FIG. 3, for example), may contact with an adjacent
component such as a vane 22 or an adjacent seal 50, to provide sealing and
reduce
leakage of a fluid. In the exemplary embodiment shown in FIGS. 5 and 6, that
contact
face 52 is substantially flat. The support wall 58 supports at least a portion
of the
sealing wall 57 and transfers a portion of the contact loads from the sealing
wall 57 to
the support portion 59 of the seal 50, which in turn transfers it to the
fairing 40. As
shown in FIG. 5, the sealing wall 57, the support wall 58 and the support
portion 56
may form a cavity profile 53 having sufficient flexibility and strength to
provide
effective sealing. In the exemplary embodiments shown in FIG. 4 and 5, the
cavity
profile 53 has a generally triangular shape. Other suitable profiles, such as,
for
example, shown as items 103 in FIG. 7, item 123 in FIG. 8 and item 148 in FIG.
10,
may be used alternatively.
FIG. 6 shows a schematic cross-sectional view of two adjacent components
71, 72 sealingly engaged with each other, according to an exemplary embodiment
of
the present invention. The two adjacent components 71, 72 may be, in one
example,
the first fairing 81 having a first seal 61 and the second fairing 82 having a
second seal
62, shown in FIG. 3. FIG. 6 shows a cross-section of the interface between two
fairings 81, 82, having the two adjacent seals 61, 62 after assembly, such as
in a stator
assembly 80. In FIG. 6, the contact faces 52 of the two seals 61, 62 are
engaged such
that there is no gap between the seals, providing full sealing. It is possible
that, in
some limited cases due to manufacturing tolerances at some locations, or due
to
certain operating conditions in the engine, there may be a small clearance
between the
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two seals that are not significant compared to conventional assemblies.
Methods of
mounting and bonding a seal to a fairing as described herein can be used to
couple
each seal with the corresponding component.
FIG. 7 shows a schematic cross-sectional view of an alternative exemplary
embodiment 100 of the present invention, showing two adjacent components 71,
72
having seals 101, 102. The seals 101, 102 have a cavity profile 103 that is
generally
circular in shape. Other suitable cavity profile shapes may also be used. A
notable
feature of the seals 101, 102 shown in FIG. 7 is that the contact face that
provides
sealing is non-planar. A non-planar contact face, such as shown for example in
FIG. 7,
provides advantages in some applications, such as, for example, in cases
involving
significant movements between the two adjacent components 71, 72. The seal 101
has
support flanges 154, 155 that are used for mounting the seal 101 to the first
component 71. Methods of mounting and bonding a seal to a fairing as described
herein can be used to couple each seal 101, 102 with the corresponding
component 71,
72.
FIG. 8 shows a schematic cross-sectional view of another alternative
exemplary embodiment 120 of the present invention, showing two adjacent
components 71, 72 having seals 121, 122. The seals 121, 122 have a cavity
profile 123
that is a composite of rectangular and circular shapes. Other suitable cavity
profile
shapes may also be used. The contact face 127 is planar. The seal 121 has
support
flanges 124, 125 that are used for mounting the seal 121 to the first
component 71.
The support flange 125 has a different geometry from the support flange 124.
Methods
of mounting and bonding a seal to a fairing as described herein can be used to
couple
each seal 121, 122 with the corresponding component 71, 72.
FIG. 9 shows a schematic cross-sectional view of another alternative
exemplary embodiment 130 of the present invention, showing two adjacent
components 71, 72 having seals 131, 132. Unlike the other embodiments shown in
FIGS. 6-8, the seals 131, 132 do not have a cavity inside. The first seal 131
has a
single support flange 135. The second seal 132 has a different geometry from
the first
seal 131, and has a single support flange 136. The contact face 137 is planar.
Methods
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of mounting and bonding a seal to a fairing as described herein can be used to
couple
each seal 131, 132 with the corresponding component 71, 72.
FIG. 10 shows a schematic cross-sectional view of another alternative
exemplary embodiment 140 of the present invention, showing two adjacent
components 71, 72 having seals 141, 142. The seal 142 has a cavity profile 148
that is
a composite of rectangular and circular shapes. Other suitable cavity profile
shapes
may also be used. The seal 141 does not have a cavity inside. The contact face
147 is
planar. The seal 141 has support flanges 145, and the seal 142 has support
flanges
144, 146 that are used for mounting the seals to the corresponding components
71, 72.
The support flange 144 has a different geometry from the support flange 146.
Methods
of mounting and bonding a seal to a fairing as described herein can be used to
couple
each seal 141, 142 with the corresponding component 71, 72.
FIG. 11 shows a flow chart schematically showing an exemplary embodiment
of a method 500 for manufacturing an integrated seal 50 on a component such as
a
fairing 40. The method 500 comprises the step 510 of supplying a component,
such as
for example, a fairing 40. The fairing 40 may be made from a known material,
such
as, for example, nylon, and made by a known process, such as for example,
injection
molding. The fairing may have has an edge portion 41 having axial edges (see
FIG. 5
for example). The method 500 further comprises the step 515 of forming a
profile 44
on the edge portion 41. For example, the axial edges are preferably machined
to have
a suitable contour corresponding to the contours of an adjacent component
during
assembly, such as for example, a vane 22 in a stator assembly 80. The method
500
further comprises the step 520 of supplying a seal 50, such as, for example
shown in
FIGS. 5-10 and described previously herein.
The method 500 further comprises the step 525 of preparing the component
surface 43 (see FIG. 5). The surface 43 may be cleaned with an alcohol wipe to
remove dirt. The surface 43 may also be sanded using known methods. The method
500 further comprises the step 530 of applying a bond preparation on a surface
43 on
the edge portion 41. This can be done, for example, by applying a primer to
the
surface 43 of the component. A primer having isopropyl alcohol, acetone and
xylene
works well for this application. A commercially available primer, such as
Silicone
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Bonding Primer supplied by GE Silicone or its commercial replacement, can be
used.
Parts are allowed to dry after the application of primer. In some
applications, the step
530 of applying a bond preparation may also include applying a plasma
treatment to
the surface 43 on the edge portion 41.
Optionally, the method 500 comprises a step 535 of applying a pressure
sensitive adhesive (PSA) tape to the component surface 43 or the seal 50. A
double
sided PSA tape may be used to hold the seal 50 in place during mounting. The
PSA is
preferably used on the side of the fairing that is opposite to the flow path
side.
The method 500 further comprises the step 540 of applying a bonding
material 48 on the seal 50. The bonding material is applied to the bonding
surfaces 43
and interior portions of the support flanges 54, 55. The bonding material is
preferably
Silicone RTV for a stator assembly 80 application in a gas turbine engine.
Other
suitable bonding materials may be used as appropriate for specific
applications.
The method 500 further comprises the step 545 of mounting the seal 50 to the
component 40. The flanges 54, 55 of the seal 50 are mounted on the edge
portion 41
of the component, such as the fairing 40. In an optional step 550, the seal 50
and the
fairing 40 may be optionally clamped together using a suitable clamping
fixture in
order to provide intimate contact during bonding between the seal 50 and the
fairing
40. In step 555, the bond material 48 between the seal 50 and the edge portion
41 is
cured. When Silicone RTV is used for bonding, curing may be completed in about
7
days. The bonds cure sufficiently for handling in about 24 hours. Other known
methods may also be used for curing.
As used herein, an element or step recited in the singular and proceeded with
the word "a" or "an" should be understood as not excluding plural said
elements or
steps, unless such exclusion is explicitly recited. When introducing
elements/components/steps etc. of components or assemblies described and/or
illustrated herein, the articles "a", "an", "the" and "said" are intended to
mean that
there are one or more of the element(s)/component(s)/etc. The terms
"comprising",
"including" and "having" are intended to be inclusive and mean that there may
be
additional element(s)/component(s)/etc. other than the listed
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element(s)/component(s)/etc. Furthermore, references to "one embodiment" of
the
present invention are not intended to be interpreted as excluding the
existence of
additional embodiments that also incorporate the recited features.
This written description uses examples to disclose the invention, including
the best mode, and also to enable any person skilled in the art to make and
use the
invention. The patentable scope of the invention is defined by the claims, and
may
include other examples that occur to those skilled in the art. Such other
examples are
intended to be within the scope of the claims if they have structural elements
that do
not differ from the literal language of the claims, or if they include
equivalent
structural elements with insubstantial differences from the literal languages
of the
claims.
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