U.S. patent application number 14/974555 was filed with the patent office on 2017-06-22 for combustor floating collar assembly.
The applicant listed for this patent is Pratt & Whitney Canada Corp.. Invention is credited to GAETAN GIRARD, DOUGLAS MACCAUL.
Application Number | 20170176004 14/974555 |
Document ID | / |
Family ID | 59066982 |
Filed Date | 2017-06-22 |
United States Patent
Application |
20170176004 |
Kind Code |
A1 |
MACCAUL; DOUGLAS ; et
al. |
June 22, 2017 |
COMBUSTOR FLOATING COLLAR ASSEMBLY
Abstract
A combustor floating collar assembly having a floating collar
disposed about an opening in an outer surface of a combustor liner.
The floating collar is displaceable relative to the outer surface.
A retention plate is attached to the outer surface of the combustor
liner and traps the floating collar between the outer surface and
the retention plate. At least a portion of the retention plate
engages the floating collar and biases it toward the outer
surface.
Inventors: |
MACCAUL; DOUGLAS; (VARENNES,
CA) ; GIRARD; GAETAN; (OUTREMONT, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Pratt & Whitney Canada Corp. |
Longueuil |
|
CA |
|
|
Family ID: |
59066982 |
Appl. No.: |
14/974555 |
Filed: |
December 18, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F23R 3/002 20130101;
F23R 3/283 20130101; F23R 2900/00012 20130101 |
International
Class: |
F23R 3/00 20060101
F23R003/00; F23R 3/28 20060101 F23R003/28 |
Claims
1. A combustor floating collar assembly, comprising: a floating
collar disposed about an opening in an outer surface of a combustor
liner, the floating collar being displaceable relative to the outer
surface; and a retention plate attached to the outer surface of the
combustor liner, the retention plate trapping the floating collar
between the outer surface and the retention plate, at least a
portion of the retention plate engaging a portion of the floating
collar and biasing the floating collar toward the outer
surface.
2. The floating collar assembly of claim 1, wherein the retention
plate includes a substantially planar middle portion extending
radially outwardly to an attachment portion being attached to the
outer surface.
3. The floating collar assembly of claim 2, wherein retention plate
includes an inner biasing portion extending radially inwardly from
the substantially planar middle portion, the inner biasing portion
extending toward the outer surface and contacting the floating
collar.
4. The floating collar assembly of claim 3, wherein said inner
biasing portion of the retention plate contacting the floating
collar is curved toward the outer surface.
5. The floating collar assembly of claim 2, wherein the attachment
portion is curved toward the outer surface.
6. The floating collar assembly of claim 2, wherein the attachment
portion of the retention plate is fixedly attached to the outer
surface.
7. The floating collar assembly of claim 6, wherein the attachment
portion of the retention plate is welded to the outer surface.
8. The floating collar assembly of claim 1, wherein the floating
collar is positioned on an annular boss of the outer surface, the
retention plate including a substantially planar middle portion
extending radially outward to an attachment portion being attached
to the boss.
9. The floating collar assembly of claim 1, wherein said portion of
the retention plate which engages the portion of the floating
collar prevents displacement of the floating collar in a direction
normal to the outer surface.
10. A gas turbine engine combustor, comprising: an annular
combustion chamber defined by a combustor liner, the combustor
liner having a plurality of openings therein extending between an
inner surface and an outer surface of the combustor liner; a
plurality of floating collars each disposed about one of the
openings in the outer surface of the combustor liner, each floating
collar being displaceable relative to the outer surface; and a
plurality of retention plates attached to the outer surface, each
retention plate trapping a corresponding one of the floating
collars between the outer surface and the retention plate, at least
a portion of each retention plate engaging a portion of the
floating collar and biasing the floating collar toward the outer
surface.
11. The combustor of claim 10, wherein each retention plate
includes a substantially planar portion middle extending radially
outwardly to an attachment portion being fixedly attached to the
outer surface.
12. The combustor of claim 11, wherein the retention plate includes
an inner biasing portion extending radially inwardly from the
substantially planar middle portion, the substantially planar
middle portion and the inner biasing portion overlaying the
floating collar, the inner biasing portion extending toward the
outer surface and contacting the floating collar.
13. The combustor of claim 12, wherein the inner biasing portion of
the retention plate contacting the floating collar is curved toward
the outer surface.
14. The combustor of claim 10, wherein each floating collar is
positioned on an annular boss of the outer surface, the
corresponding retention plate including a substantially planar
middle portion extending radially outwardly to an attachment
portion being fixedly attached to the boss.
15. The combustor of claim 10, further comprising at least one
igniter or at least one fuel nozzle, said nozzle or fuel nozzle
being inserted through a corresponding one of the openings, and
engaging a corresponding floating collar.
16. A method for installing an annular floating collar about an
opening in a liner of a gas turbine engine combustor, comprising:
positioning the floating collar on an outer surface of the liner,
the floating collar being displaceable with respect to the outer
surface; attaching a retention plate to the outer surface to trap
the floating collar between the outer surface and the retention
plate; and biasing the floating collar toward the outer surface
with at least a portion of the retention plate.
17. The method of claim 16, wherein biasing the floating collar
toward the outer surface includes compressive loading the floating
collar with said portion of the retention plate.
18. The method of claim 17, wherein compressive loading the
floating collar includes increasing a shear restraint of the
floating collar in a plane of the outer surface.
19. The method of claim 16, wherein biasing the floating collar
includes welding the retention plate to the outer surface to engage
the floating collar with said portion of the retention plate.
20. The method of claim 16, further comprising inserting a fuel
nozzle or an igniter through the opening in the liner to engage the
floating collar, and removing the fuel nozzle or the igniter from
the opening while maintaining in place the floating collar and
retention plate.
Description
TECHNICAL FIELD
[0001] The disclosure relates generally to gas turbine engine
combustors and, more particularly, to a floating collar assembly
for a combustor fuel nozzle or igniter.
BACKGROUND
[0002] Igniters of gas turbine engine combustors are typically
retained on a boss of the gas generator case by being directly
threaded into the boss or by being held in position with bolts. The
igniters interface with the combustion chamber through a floating
collar that is retained by a bracket. The bracket provides the
collar with freedom of movement in the plane of its contact with
the boss, and the collar is free to move normal to the bracket
boss.
[0003] During engine operation, the collars may be exposed to
aerodynamic loads generated by the upstream compressor which exert
a force on the floating collar. When this force is greater than the
inertial or gravitational loads on the collar, the collar is
displaced. The dynamic nature of such aerodynamic loading, coupled
with combustor dynamics, can create a fretting problem due to the
intermittent displacement/impact of the collar against the igniter,
or against the bracket or boss.
SUMMARY
[0004] There is provided a combustor floating collar assembly,
comprising: a floating collar disposed about an opening in an outer
surface of a combustor liner, the floating collar being
displaceable relative to the outer surface; and a retention plate
attached to the outer surface of the combustor liner, the retention
plate trapping the floating collar between the outer surface and
the retention plate, at least a portion of the retention plate
engaging a portion of the floating collar and biasing the floating
collar toward the outer surface.
[0005] There is also provided a gas turbine engine combustor,
comprising: an annular combustion chamber defined by a combustor
liner, the combustor liner having a plurality of openings therein
extending between an inner surface and an outer surface of the
combustor liner; a plurality of floating collars each disposed
about one of the openings in the outer surface of the combustor
liner, each floating collar being displaceable relative to the
outer surface; and a plurality of retention plates attached to the
outer surface, each retention plate trapping a corresponding one of
the floating collars between the outer surface and the retention
plate, at least a portion of each retention plate engaging a
portion of the floating collar and biasing the floating collar
toward the outer surface.
[0006] There is further provided a method for installing an annular
floating collar about an opening in a liner of a gas turbine engine
combustor, comprising: positioning the floating collar on an outer
surface of the liner, the floating collar being displaceable with
respect to the outer surface; attaching a retention plate to the
outer surface to trap the floating collar between the outer surface
and the retention plate; and biasing the floating collar toward the
outer surface with at least a portion of the retention plate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Reference is now made to the accompanying figures in
which:
[0008] FIG. 1 is a schematic cross-sectional view of a gas turbine
engine;
[0009] FIG. 2 is a side view of a combustor of the gas turbine
engine of FIG. 1, the combustor having a floating collar assembly
according to an embodiment of the present disclosure;
[0010] FIG. 3 is a perspective view of a floating collar assembly
on the combustor of FIG. 2, according to an embodiment of the
present disclosure;
[0011] FIG. 4A is an enlarged, partially-sectioned perspective view
of the floating collar assembly of FIG. 3;
[0012] FIG. 4B is a side view of the enlarged, partially-sectioned
view of the floating collar assembly of FIG. 4A, shown without a
floating collar; and
[0013] FIG. 4C is another, enlarged partial side view of the
floating collar assembly of FIGS. 3-4B.
DETAILED DESCRIPTION
[0014] FIG. 1 illustrates a gas turbine engine 10 of a type
preferably provided for use in subsonic flight, generally
comprising in serial flow communication a fan 12 through which
ambient air is propelled, a compressor section 14 for pressurizing
the air, a combustor 16 in which the compressed air is mixed with
fuel and ignited for generating an annular stream of hot combustion
gases, and a turbine section 18 for extracting energy from the
combustion gases. The combustor 16 includes a combustion chamber 17
defined by a combustor liner 19 which contains and conveys the hot
combustion gases. The combustor 16 is housed within a gas generator
case 3.
[0015] Referring to FIG. 2, the shape of the combustor 16 is
typically defined by the combustor liner 19 which may include one
or more relatively thin sheet metal walls supported within a plenum
filled with compressed air. The compressed air typically enters the
combustor 16 through various openings 15 in the combustor liner 19
and/or via fuel nozzles, to mix with the fuel sprayed within the
combustor 16. Fuel nozzles or igniters are inserted into the
combustor 16 through some of the openings 15.
[0016] Many of the openings 15 are circumscribed by bosses 13,
which can be annular or another shape and protrude from an outer
surface 9 of the combustor liner 19 about the openings 15 and
coaxial therewith. The "outer surface 9" of the combustor liner 19
is the surface of the combustor liner 19 which does not face
inwardly into the combustor 16 toward the hot combustion gases. The
bosses 13 facilitate attachment or insertion of fuel nozzles or
igniters into the combustor liner 19 and allow for the mounting of
collars to improve sealing between the combustor liner 19 and the
gas generator case. The bosses 13 can be formed during the
manufacturing of the combustor liner 19, or can be attached
thereto. If attached, the bosses 13 are welded to the outer surface
9 of the combustor liner 19. Whether integral with, or attached to,
the combustor liner 19, the bosses 13 are fixedly attached to the
combustor liner 19 and are not displaced relative thereto.
[0017] Referring to FIGS. 2 and 3, a floating collar assembly 20 is
mounted to the outer surface 9 of the combustor liner 19 about one
of the openings 15. Each floating collar assembly 20, and in
particular, its floating collar, helps to seal the fuel nozzles or
igniters in the openings 15. The floating collar assemblies 20 also
help to accommodate the relative movement between the fuel nozzles
or igniters and the combustor 16, which results from thermal
expansion and contraction. The floating collar assemblies 20 can
also be used to control the flow of air from the plenum or gas
generator case into the combustion chamber enclosed by the
combustor liner 19 of the combustor 16.
[0018] FIG. 3 shows the floating collar assembly 20, according to
an embodiment of the present disclosure. The floating collar
assembly 20 (or simply "assembly 20") is mounted to the outer
surface 9 of the combustor liner 19. More particularly, and as
shown in this embodiment, the assembly 20 is mounted to one of the
bosses 13 of the outer surface 9. It will be appreciated that the
assembly 20 may be mounted directly to the outer surface 9 about an
opening therein.
[0019] The assembly 20 includes a floating collar 30, having an
annular or other shape, which engages the boss 13 and can be
displaced relative thereto. The assembly 20 also includes a
retention plate 40 which confines the floating collar 30 to the
outer surface 9 and biases the floating collar 30 toward the outer
surface 9. When a fuel nozzle or igniter 7 is inserted into the
floating collar 30, it is then radially located through a small
tolerance loose fit with the floating collar 30, allowing radial
growth and in plane play from the loose fit.
[0020] Referring to FIGS. 4A to 4C, the annular floating collar 30
has a combustor-facing first surface 32 that engages the outer
surface 9, which is represented in this embodiment by the boss 13,
and an outward-facing second surface 34. A central collar aperture
36 extends through the floating collar 30 between the first and
second surfaces 32,34, and is generally co-axial with the opening
in the combustor liner. The central collar aperture 36 is adapted
for axial engagement with the cylindrical body of the fuel nozzle
or igniter, in order to effectively seal the combustor liner from
uncontrolled entry of compressed air from the plenum. More
particularly, a pressure differential across the floating collar 30
seals the first surface 32 to the boss 13. The first surface 32 is
disposed on the boss 13 such that the floating collar 30 can be
displaced relative to the boss 13, as will be described in greater
detail below. The displacement of the floating collar 30 may be
caused, for example, by aerodynamic loads from the compressor or
from vibration of the whole assembly.
[0021] Conventional floating collars can fret at the contact points
with the fuel nozzle or igniter, or at the contact point with the
boss, because of the intermittent displacement or "chattering"
caused by the aerodynamic or vibration loads encouraging the
displacement of the floating collar 30 against the fuel nozzle or
igniter in a highly dynamic environment. The retention plate 40
disclosed herein helps to reduce such fretting by biasing the
floating collar 30 toward the boss 13 to frictionally reduce at
least some of this chattering movement.
[0022] More particularly, the retention plate 40 is attached to the
outer surface 9 and/or its boss 13 such that relative displacement
is eliminated between the retention plate 40 and the boss 13. The
retention plate 40 can be welded to the boss 13 to form weld lines
42 between the retention plate 40 and the boss 13. The retention
plate can also be attached to outer surface 9 using any other
technique. When installed, the retention plate 40 overlies both the
boss 13 and the floating collar 30 such that at least some portion
of the floating collar 30 is positioned between the boss 13 and the
retention plate 40. The dimensional interference of the retention
plate 40 with the floating collar 30 frictionally limits
displacement of the floating collar 30 relative to the boss 13,
thereby confining the floating collar 30 to the boss 13. It can
thus be appreciated that the retention plate 40 "retains" the
floating collar 30 in sealing engagement with the fuel nozzle or
igniter, and traps the floating collar 30 between itself and the
outer surface 9.
[0023] Referring specifically to FIG. 4C, and in addition to this
retaining functionality, the retention plate 40 also provides a
"loading" functionality. More particularly, at least a portion of
the retention plate 40 engages at least a portion of the floating
collar 30 and biases it toward the boss 13 with a biasing force F.
The engagement of the retention plate 40 with the floating collar
30 provides a compressive load, acting substantially radially
inward on the second surface 34 of the floating collar 30, which
pushes the (inner) first surface 32 of the floating collar 30
toward and/or against the boss 13. When the first surface 32 abuts
against and engages the boss 13, friction between the two surfaces
creates a shear force or restraint of the floating collar 30 in a
plane of the boss 13. The shear restraint in the plane of the boss
13 can be greater than the aerodynamic loads which impact the
floating collar 30.
[0024] The retention plate 40 of the assembly 20 disclosed herein
therefore maintains its "retention" functionality while also
helping to reduce or eliminate the fretting associated with
conventional floating collars. This may be achieved, for example,
because the biasing engagement of the retention plate 40 limits the
displacement of the floating collar 30 relative to the boss 13. For
example, the biasing force F applied by the retention plate 40 may
allow the floating collar 30 to displace only in a plane that is
parallel to the plane of the boss 13. The biasing engagement of the
retention plate 40 may thus reduce or prevent displacement of the
floating collar 30 in a direction parallel to a center axis of the
opening in the combustor liner. In such instances, the retention
plate 40 is used to radially (i.e. a direction along the center
axis of the opening) secure the floating collar 30 to the boss 13,
while still permitting relative movement between the floating
collar 30 and the boss 13 only in the plane of the boss 13, or
directly along the outer surface 9. Allowing the floating collar 30
to be displaced relative to the boss 30 or outer surface 9 helps
accommodate the radial growth of the components of the assembly 20,
and the in-plane play from the loose fit between the fuel nozzle or
igniter and the floating collar 30.
[0025] Various embodiments of the retention plate 40 can achieve
such functionality, all of which are within the scope of the
present disclosure. FIGS. 4A-4C show one such embodiment of the
retention plate 40. The retention plate 40 includes a substantially
planar middle portion 44 extending between two attachment portions
46 which are attached to the outer surface 9 and which extend
radially outwardly from the middle portion 44. The attachment
portions 46 may be curved at their ends toward the outer surface 9.
A free extremity 48 of each attachment portion 46 is fixedly
attached to the boss 13 or outer surface 9. In one embodiment, each
free extremity 48 can be welded to the boss 13 to form weld lines
42 between the retention plate 40 and the boss 13, or the outer
surface 9 of the combustor liner. The distance between the free
extremities 48 in this embodiment is greater than a diameter of the
floating collar 30, such that the retention plate 40 overlies a
greater extent of the outer surface 9 than the floating collar
30.
[0026] The retention plate 40 also has one or more inner biasing
portions 49 of the retention plate 40 which engage the floating
collar 30, and which extend radially inwardly from the middle
portion 44. The inner biasing portion 49 can be curved, bent, or
otherwise protrude toward the boss 13. Such a curved inner biasing
portion 49 provides a curved line of contact with the second
(outer) surface 34 of the floating collar 30 which helps to reduce
stress concentrations. In the embodiment shown in FIGS. 4A-4C, the
retention plate 40 can engage the floating collar 30 via one or
more dimples or depressions 49A in the retention plate 40. Each
depression 49A extends from the planar portion 44 toward the boss
13 and contacts the second surface 34 of the floating collar 30.
Other shapes for the inner biasing portion 49 of the retention
plate 40 engaging the floating collar 30 are also possible,
including "U"-shaped depressions.
[0027] The depression or engagement can be formed during
installation of the assembly 20. For example, while welding the
free extremities 48 of the attachment portion 46 to the boss 13, it
is possible to also manipulate the retention plate 40 to engage the
floating collar. The biasing load can be therefore be pre-loaded,
and created by bending the retention plate 40 so that it interferes
with the floating collar 30 at assembly of the retention plate 40
to the boss 13. In some instances, the retention plate 40 will be
secured to the boss 13 before positioning the floating collar 30 on
the boss 13. This would allow the floating collar 30 to be a
replaceable item with no need to remanufacture the collar assembly
20.
[0028] Still referring to FIGS. 4A to 4C, there is also disclosed a
method for installing the annular floating collar 30 about the
opening in the combustor liner. The method includes positioning the
floating collar 30 on the outer surface 9 such that the floating
collar 30 is displaceable with respect to the outer surface 9. The
retention plate 40 is attached to the outer surface 9 to trap the
floating collar 30 between the retention plate 40 and the outer
surface 9. The retention plate 40 is manipulated to bias the
floating collar 30 toward the boss 13. The biased floating collar
30 may be prevented from being displaced in a direction normal to
the outer surface 9, and may be allowed to displace along the outer
surface 9.
[0029] In an embodiment, the method includes applying a heat
treatment to the welded or attached retention plate 40. This can
permit control/normalization of the load applied on the floating
collar 30 by the biasing retention plate 40.
[0030] There is also disclosed a method for dampening displacement
of an annular floating collar 30 that is already installed. More
particularly, the method helps to dampen or reduce unwanted radial
displacement of the floating collar 30 relative to the annular boss
13 in assemblies where the floating collar 30 is confined to the
boss 13 with the retention plate 40 disposed over the floating
collar 30 and fixed to the boss 13. Such a method can be used to
adapt an existing floating collar assembly to reduce displacement
of the floating collar, such as during after-market maintenance.
The method includes biasing the floating collar 30, by bending or
another mechanical manipulation of a portion of the retention plate
40, toward the boss 13 with at least a portion of the retention
plate 40. Alternatively, an existing retention plate can be
replaced with a pre-formed retention plate 40 having a biasing
element 49 as described above.
[0031] In light of the preceding, it can thus be appreciated that a
fuel nozzle or igniter can be inserted through the opening 15 and
remove therefrom without any part of the floating collar assembly
20 being disturbed or removed from the combustor liner. This
ability of the retention plate 40 to retain itself and the floating
collar 40 in place, even when the fuel nozzle or igniter is
positioned within the opening 15 of the combustor liner 19,
prevents these components repositioning themselves relative to the
retention plate 40 during installation. This can be problematic
during installation of a collar assembly. Such functionality also
improves maintenance of the features of the assembly 20 because
complete disassembly of the assembly 20 and its components is not
required. Furthermore, easier access can be provided to the
internal components of the gas generator assembly, e.g. for
boroscope inspection. These possibilities can be achieved by
enhancing the components of a conventional floating collar
assembly, and does not require adding additional parts.
[0032] In contrast to some conventional floating collar assemblies,
the assembly 20 disclosed herein does not require other components
(e.g. the fuel nozzle, the igniter, or features of these) to
maintain the floating collar 30 in place, or to apply the biasing
force F with the retention plate 40. Instead, the assembly 20
disclosed herein presents a self-contained "one-piece" solution,
wherein the retention plate 40 both retains the floating collar in
place, and applies compressive loading thereto.
[0033] The above description is meant to be exemplary only, and one
skilled in the art will recognize that changes may be made to the
embodiments described without departing from the scope of the
invention disclosed. Still other modifications which fall within
the scope of the present invention will be apparent to those
skilled in the art, in light of a review of this disclosure, and
such modifications are intended to fall within the appended
claims.
* * * * *