U.S. patent application number 14/830497 was filed with the patent office on 2017-02-23 for seal assembly for rotational equipment.
The applicant listed for this patent is United Technologies Corporation. Invention is credited to William K. Ackermann, Clifton J. Crawley, JR., Frederick M. Schwarz.
Application Number | 20170051751 14/830497 |
Document ID | / |
Family ID | 56896334 |
Filed Date | 2017-02-23 |
United States Patent
Application |
20170051751 |
Kind Code |
A1 |
Ackermann; William K. ; et
al. |
February 23, 2017 |
SEAL ASSEMBLY FOR ROTATIONAL EQUIPMENT
Abstract
Assemblies are provided for rotational equipment. One of these
assemblies includes a rotor disk structure, a stator structure and
a seal assembly. The rotor disk structure includes a rotor disk and
a seal land circumscribing the rotor disk. The stator structure
circumscribes the seal land. The seal assembly is configured for
sealing a gap between the stator structure and the seal land, where
the seal assembly includes a non-contact seal.
Inventors: |
Ackermann; William K.; (East
Hartford, CT) ; Crawley, JR.; Clifton J.;
(Glastonbury, CT) ; Schwarz; Frederick M.;
(Glastonbury, CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
United Technologies Corporation |
Hartford |
CT |
US |
|
|
Family ID: |
56896334 |
Appl. No.: |
14/830497 |
Filed: |
August 19, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16J 15/442 20130101;
F01D 5/06 20130101; F01D 5/082 20130101; Y02T 50/671 20130101; F05D
2240/56 20130101; F04D 29/083 20130101; Y02T 50/60 20130101; Y02T
50/676 20130101; F04D 29/545 20130101; F01D 11/02 20130101; F04D
29/582 20130101; F04D 29/542 20130101; F04D 29/324 20130101; F23R
3/10 20130101; Y02T 50/673 20130101 |
International
Class: |
F04D 29/08 20060101
F04D029/08; F23R 3/10 20060101 F23R003/10; F04D 29/54 20060101
F04D029/54; F04D 29/32 20060101 F04D029/32; F04D 29/58 20060101
F04D029/58 |
Claims
1. An assembly for rotational equipment, the assembly comprising: a
rotor disk structure including a rotor disk and a seal land
circumscribing the rotor disk; a stator structure circumscribing
the seal land; and a seal assembly configured for sealing a gap
between the stator structure and the seal land, wherein the seal
assembly includes a non-contact seal.
2. The assembly of claim 1, wherein the non-contact seal is a
hydrostatic non-contact seal.
3. The assembly of claim 1, wherein the non-contact seal comprises:
an annular base; a plurality of shoes arranged around and radially
adjacent the seal land; and a plurality of spring elements, each of
the spring elements radially between and connecting a respective
one of the shoes to the base.
4. The assembly of claim 1, wherein the seal land is an outer hub
of the rotor disk structure.
5. The assembly of claim 1, wherein the rotor disk includes an
annular counterweight mass and an annular web extending radially
inward to the counterweight mass.
6. The assembly of claim 1, wherein the seal land includes a
cylindrical outer surface, and the gap extends radially between the
stator structure and the outer surface.
7. The assembly of claim 6, wherein the seal land comprises an
axially extending annular flange which forms the outer surface.
8. The assembly of claim 1, further comprising: a bladed rotor
assembly including a second rotor disk structure; and a linkage
extending axially between and connected to the rotor disk structure
and the second rotor disk structure.
9. The assembly of claim 8, wherein the bladed rotor assembly is a
compressor rotor assembly.
10. The assembly of claim 8, further comprising a nozzle configured
to direct cooling air onto the second rotor disk structure.
11. The assembly of claim 10, wherein the second rotor disk
structure is in a last stage of a high pressure compressor
section.
12. The assembly of claim 10, wherein the nozzle comprises a
tangential onboard injection nozzle.
13. The assembly of claim 10, further comprising: a guide
circumscribing the linkage and configured to form a duct with the
linkage; wherein the duct flows at least some of the cooling air
directed out from the nozzle axially along the linkage, and the
guide is configured with the stator structure.
14. The assembly of claim 13, wherein the duct extends towards the
seal assembly, and the seal assembly is configured with an aperture
to provide a controlled leakage axially thereacross.
15. The assembly of claim 13, wherein the guide includes an
aperture which receives cooling air from the duct, and the aperture
is configured to direct the received cooling air into a cavity for
cooling the stator structure.
16. The assembly of claim 8, wherein the linkage is a conical
linkage.
17. The assembly of claim 8, further comprising: a combustor
downstream of the bladed rotor assembly; and a diffuser structure
forming a diffuser plenum around the combustor, wherein the stator
structure is configured with the diffuser structure.
18. An aircraft propulsion system, comprising: a rotor disk
structure including a rotor disk, wherein the rotor disk includes
an annular counterweight mass and an annular web extending radially
inward to the counterweight mass; a stator structure; and a seal
assembly including a first seal element and a second seal element
configured to form a seal with the first seal element, the first
seal element configured with the rotor disk structure and
circumscribing the rotor disk, and the second seal element
configured with the stator structure and circumscribing the first
seal element.
19. The aircraft propulsion system of claim 18, wherein the first
seal element is an annular seal land configured as an outer hub of
the rotor disk structure, and wherein the second seal element is a
non-contact seal.
19. The aircraft propulsion system of claim 18, wherein the first
seal element comprises a knife-edge seal element, and the second
seal element comprises an abradable seal land.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Technical Field
[0002] This disclosure relates generally to rotational equipment
and, more particularly, to a seal assembly for rotational
equipment.
[0003] 2. Background Information
[0004] Rotational equipment typically includes one or more seal
assemblies for sealing gaps between rotors and stators. A typical
seal assembly includes a contact seal with a seal element such as a
knife edge seal that engages a seal land. Such a contact seal,
however, can generate a significant quantity of heat which can
reduce efficiency of the rotational equipment as well as subject
other components of the rotational equipment to high temperatures
and internal stresses. To accommodate the high temperatures, other
components of the rotational equipment may be constructed from
specialty high temperature materials, which can significantly
increase the manufacturing and servicing costs as well as the mass
of the rotational equipment. While non-contact seals have been
developed in an effort to reduce heat within rotational equipment,
such non-contact seals can be difficult to configure within the
rotational equipment. Such non-contact seals and associated
components (e.g., shafts, linkages, etc.) may also need to be
replaced when incidental contact occurs.
[0005] There is a need in the art for improved seal assemblies for
rotational equipment.
SUMMARY OF THE DISCLOSURE
[0006] According to an aspect of the present disclosure, an
assembly is provided for rotational equipment. This assembly
includes a rotor disk structure, a stator structure and a seal
assembly. The rotor disk structure includes a rotor disk and a seal
land circumscribing the rotor disk. The stator structure
circumscribes the seal land. The seal assembly is configured for
sealing a gap between the stator structure and the seal land, where
the seal assembly includes a non-contact seal.
[0007] According to another aspect of the present disclosure, an
aircraft propulsion system is provided which includes a rotor disk
structure, a stator structure and a seal assembly. The rotor disk
structure includes a rotor disk. The rotor disk includes an annular
counterweight mass and an annular web extending radially inward to
the counterweight mass. The seal assembly includes a first seal
element and a second seal element configured to form a seal with
the first seal element. The first seal element is configured with
the rotor disk structure and circumscribes the rotor disk. The
second seal element is configured with the stator structure and
circumscribes the first seal element.
[0008] The first seal element may be an annular seal land
configured as an outer hub of the rotor disk structure. The second
seal element may be a non-contact seal. This non-contact seal may
be a hydrostatic non-contact seal.
[0009] The first seal element may include or be configured as a
knife-edge seal element. The second seal element may include or be
configured as an abradable seal land.
[0010] The non-contact seal may be a hydrostatic non-contact
seal.
[0011] The non-contact seal may include an annular base, a
plurality of shoes and a plurality of spring elements. The shoes
may be arranged around and radially adjacent the seal land. Each of
the spring elements may be radially between and connect a
respective one of the shoes to the base.
[0012] The seal land may be an outer hub of the rotor disk
structure.
[0013] The rotor disk may include an annular counterweight mass and
an annular web extending radially inward to the counterweight
mass.
[0014] The seal land may include a cylindrical outer surface. The
gap may extend radially between the stator structure and the outer
surface.
[0015] The seal land may include or be configured as an axially
extending annular flange which forms the outer surface.
[0016] A bladed rotor assembly may include a second rotor disk
structure. A linkage may extend axially between and may be
connected to the rotor disk structure and the second rotor disk
structure.
[0017] The bladed rotor assembly may be a compressor rotor
assembly.
[0018] A nozzle may be included and configured to direct cooling
air onto the second rotor disk structure. The nozzle may be
configured as or include a tangential onboard injection nozzle. In
addition or alternatively, the second rotor disk structure may be a
downstream-most rotor disk structure (e.g., an axially aft-most
rotor disk structure) of the bladed rotor assembly, and the bladed
rotor assembly may be a high pressure compressor rotor assembly. In
addition or alternatively, the second rotor disk structure may be
in a last stage of a high pressure compressor section.
[0019] A guide may be included and circumscribe the linkage and
configured to form a duct with the linkage. The duct may flow at
least some of the cooling air directed out from the nozzle axially
along the linkage, and the guide may be configured with the stator
structure.
[0020] The duct may extend towards the seal assembly. The seal
assembly may be configured with an aperture to provide a controlled
leakage axially thereacross.
[0021] The guide may include an aperture which receives cooling air
from the duct. The aperture may be configured to direct the
received cooling air into a cavity for cooling the stator
structure.
[0022] The linkage may be a conical linkage.
[0023] A combustor may be included and downstream of the bladed
rotor assembly. A diffuser structure may be included and form a
diffuser plenum around the combustor. The stator structure may be
configured with the diffuser structure.
[0024] The foregoing features and the operation of the invention
will become more apparent in light of the following description and
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a side cutaway illustration of a gas turbine
engine.
[0026] FIG. 2 is a side cutaway/block diagram illustration of a
combustor section of the gas turbine engine.
[0027] FIG. 3 is a side cutaway illustration of a portion of a high
pressure compressor (HPC) section and the combustor section.
[0028] FIG. 3A illustrates the components of FIG. 3 along with
select cooling air flows.
[0029] FIG. 4 is a side cutaway illustration of a portion of an
alternative high pressure compressor (HPC) section and the
combustor section.
[0030] FIG. 4A illustrates the components of FIG. 4 along with
select cooling air flows.
[0031] FIG. 5 is a perspective illustration of a non-contact
seal.
[0032] FIG. 6 is a perspective illustration of a portion of the
non-contact seal of FIG. 5.
[0033] FIG. 7 is a cross-sectional illustration of a portion of the
non-contact seal of FIG. 5.
[0034] FIGS. 8 and 9 are side sectional illustrations of
alternative portions of the non-contact seal of FIG. 5.
[0035] FIG. 10 is an end view illustration of a portion of a
plate.
[0036] FIG. 11 is a force balance diagram of a shoe depicting
aerodynamic forces, spring forces and secondary seal forces acting
on a shoe.
DETAILED DESCRIPTION OF THE INVENTION
[0037] FIG. 1 is a side cutaway illustration of a gas turbine
engine 10 for an aircraft propulsion system. This turbine engine 10
is configured as a geared turbofan engine, and extends along an
axial centerline 12 between an upstream airflow inlet 14 and a
downstream airflow exhaust 16. The turbine engine 10 includes a fan
section 18, a compressor section 19, a combustor section 20 and a
turbine section 21. The compressor section 19 includes a low
pressure compressor (LPC) section 19A and a high pressure
compressor (HPC) section 19B. The turbine section 21 includes a
high pressure turbine (HPT) section 21A and a low pressure turbine
(LPT) section 21B.
[0038] The engine sections 18-21 are arranged sequentially along
the centerline 12 within an engine housing 22. This housing 22
includes an inner case 24 (e.g., a core case) and an outer case 26
(e.g., a fan case). The inner case 24 may house one or more of the
engine sections 19-21 (e.g., an engine core), and may be housed
within an inner nacelle structure/inner fixed structure (not shown)
which provides an aerodynamic cover for the inner case 24. The
inner case 24 may be configured with one or more axial and/or
circumferential inner sub-casings; e.g., case segments. The outer
case 26 may house at least the fan section 18, and may be housed
within an outer nacelle structure (not shown) which provides an
aerodynamic cover for the outer case 26. Briefly, the outer nacelle
structure along with the outer case 26 overlaps the inner nacelle
structure thereby defining a bypass gas path 28 radially between
the nacelle structures. The outer case 26 may be configured with
one or more axial and/or circumferential outer case segments.
[0039] Each of the engine sections 18-19B, 21A and 21B includes a
respective rotor 30-34. Each of these rotors 30-34 includes a
plurality of rotor blades arranged circumferentially around and
connected to one or more respective rotor disks. The rotor blades,
for example, may be formed integral with or mechanically fastened,
welded, brazed, adhered and/or otherwise attached to the respective
rotor disk(s). Each of the rotors 31-34 may also include one or
more rotor disk linkages, which interconnect adjacent rotor disks
within the respective rotor and/or the rotor to a shaft.
[0040] The fan rotor 30 is connected to a gear train 36, for
example, through a fan shaft 38. The gear train 36 and the LPC
rotor 31 are connected to and driven by the LPT rotor 34 through a
low speed shaft 39. The HPC rotor 32 is connected to and driven by
the HPT rotor 33 through a high speed shaft 40. The shafts 38-40
are rotatably supported by a plurality of bearings 42; e.g.,
rolling element and/or thrust bearings. Each of these bearings 42
is connected to the engine housing 22 (e.g., the inner case 24) by
at least one stationary structure such as, for example, an annular
support strut.
[0041] During operation, air enters the turbine engine 10 through
the airflow inlet 14. This air is directed through the fan section
18 and into a core gas path 44 and the bypass gas path 28. The core
gas path 44 extends sequentially through the engine sections 19-21.
The air within the core gas path 44 may be referred to as "core
air". The air within the bypass gas path 28 may be referred to as
"bypass air".
[0042] The core air is compressed by the compressor rotors 31 and
32 and directed into a combustion chamber 46 of a combustor 47 in
the combustor section 20 (see also FIG. 2). Fuel is injected into
the combustion chamber 46 and mixed with the compressed core air to
provide a fuel-air mixture. This fuel air mixture is ignited and
combustion products thereof flow through and sequentially cause the
turbine rotors 33 and 34 to rotate. The rotation of the turbine
rotors 33 and 34 respectively drive rotation of the compressor
rotors 32 and 31 and, thus, compression of the air received from a
core airflow inlet. The rotation of the turbine rotor 34 also
drives rotation of the fan rotor 30, which propels bypass air
through and out of the bypass gas path 28. The propulsion of the
bypass air may account for a majority of thrust generated by the
turbine engine 10, e.g., more than seventy-five percent (75%) of
engine thrust. The turbine engine 10 of the present disclosure,
however, is not limited to the foregoing exemplary thrust
ratio.
[0043] FIG. 3 illustrates an assembly 48 for the turbine engine 10.
This turbine engine assembly 48 includes an assemblage of stator
elements (e.g., 47, 50, 52, 54 and 56), a rotor 58 and a seal
assembly 60.
[0044] The assemblage of stator elements includes the combustor 47
(see FIG. 2) and a diffuser structure 50. Referring to FIG. 2, the
diffuser structure 50 is configured to form an annular diffuser
plenum 62 that surrounds the combustor 47. For example, a radially
outer portion 64 of the diffuser structure 50 is spaced apart from
and circumscribes the combustor 47. This outer portion 64 may be
configured as a segment of or otherwise connected to the inner case
24. A radially inner portion 66 of the diffuser structure 50 is
spaced apart from and is disposed radially within the combustor
47.
[0045] Referring again to FIG. 3, the assemblage of stator elements
also includes a stator vane assembly 52, a fixed stator structure
54 and a flow guide 56. The stator vane assembly 52 is configured
to guide core air, which was compressed by the rotor 58, into the
diffuser structure 50. This stator vane assembly 52 includes an
array of stators vanes 68 (e.g., guide vanes) arranged
circumferentially around the centerline 12. Each of these stator
vanes 68 includes a stator vane airfoil 70, which extends radially
between an inner platform 72 and an outer platform 74. The inner
platform 72 is disposed axially between bladed rotor assemblies
(e.g., 76) of the rotor 58 and the diffuser structure 50, and may
be adjacent to one or more of the components 76 and 50. The outer
platform 74 may be connected to a turbine engine case, which may be
configured as or included in the inner case 24 (see FIG. 2).
[0046] The stator vane assembly 52 of FIG. 3 may be a segmented
stator vane assembly. The stator vanes 68 may be configured into
singlets, doublets, etc. with corresponding segments of the inner
platform 72 and the outer platform 74. To seal gaps between the
segments, the stator vane assembly 52 may include one or more
feather seals (not shown) for sealing between inner platform 72
segments and/or the outer platform 74 segments. The stator vane
assembly 52, of course, may also or alternatively include one or
more other types of seals to seal inter-segment gaps. Furthermore,
in some embodiments, the inner platform 72 and/or the outer
platform 74 may each be configured with a full-hoop body.
[0047] The stator structure 54 is configured to locate and support
at least one seal element of the seal assembly 60 such as, but not
limited to, a non-contact seal 78 or an abradable seal land 80 (see
FIG. 4). The stator structure 54 of FIG. 3, for example, includes
an annular support structure 82. This support structure 82
circumscribes the rotor 58 and, more particularly, a seal element
of the rotor 58 such as, but not limited to, an annular seal land
84 or one or more knife-edge seal elements 86 (see FIG. 4).
[0048] The support structure 82 may be configured having a
monolithic full hoop body. Herein, the term "monolithic" may
describe a component which is formed as a single unitary body. The
support structure 82, for example, includes an integral, tubular
body that is formed without any mechanically interconnected axial
and/or circumferential segments. Note, in some embodiments, a
monolithic body may include one or more bodies bonded together. In
another example, arcuate segments (e.g., halves) may be
respectively bonded together to form a full hoop body. The assembly
48 of the present disclosure, however, is not limited to the
foregoing exemplary support structure configuration.
[0049] The support structure 82 and the stator structure 54 in
general may be configured with the diffuser structure 50. The
stator structure 54 of FIG. 3, for example, includes a mounting
structure 88 which structurally ties the support structure 82 to
the diffuser structure 50. This mounting structure 88 may be formed
integral with the support structure 82. The mounting structure 88
may be mechanically attached to the diffuser structure 50 by, for
example, one or more sets of fasteners (e.g., 90). However, in
other embodiments, the support structure 82 and the stator
structure 54 in general may alternatively be formed as an integral
part of the diffuser structure 50.
[0050] The stator structure 54 may also include one or more nozzles
92. The nozzles 92 of FIG. 3 are configured as tangential onboard
injection (TOBI) nozzles. The present disclosure, however, is not
limited to any particular nozzle type or configuration. The nozzles
92 are arranged circumferentially around the centerline 12. Each of
these nozzles 92 is configured to direct cooling air onto a portion
of the rotor 58 such as, for example, a hub 94, blade roots, and/or
other portion of the bladed rotor assembly 76. The nozzles 92 may
each receive the cooling air from a respective conduit 96, which
may receive this cooling air from a heat exchanger radially
outboard of the diffuser structure 50 or another source or sources.
The nozzles 92 may be formed integral with the mounting structure
88. However, in other embodiments, one or more of the nozzles 92
may be configured as a discrete structure which is attached to or
independent of the stator structure 54.
[0051] The flow guide 56 is configured with the stator structure
54. The flow guide 56 of FIG. 3, for example, is mechanically
fastened to the mounting structure 88 by one or more fasteners 98.
The flow guide 56 circumscribes the rotor 58 and, more
particularly, a conical linkage 100 of the rotor 58. The flow guide
56 includes an annular, conical portion 102 configured to form an
annular duct 104 with the linkage 100, which duct 104 is configured
to flow at least some of the cooling air directed out from the
nozzles 92 along the linkage and towards the seal assembly 60 (see
FIGS. 3A and 4A). The flow guide 56 may include one or more cooling
apertures 106, which may be arranged around the centerline 12. Each
cooling aperture 106 extends through the conical portion 102. Each
cooling aperture 106 is configured to direct cooling air from the
duct 104 and into a (e.g., annular) cavity 108 between the flow
guide 56 and the stator structure 54 in order to cool the stator
structure 54.
[0052] The rotor 58 may be configured as one of the rotors 30-34;
e.g., the HPC rotor 32 (see FIG. 1). The rotor 58 of FIG. 3
includes at least the bladed rotor assembly 76; e.g., a final stage
high pressure compressor (HPT) rotor assembly. The bladed rotor
assembly 76 is disposed upstream of and adjacent to the stator
components 52 and 92. The bladed rotor assembly 76 includes a rotor
disk structure 110 and a plurality of rotor blades 112; e.g.,
turbine blades. These rotor blades 112 are arranged
circumferentially around and attached to the hub of the rotor disk
structure 110; e.g., via fir tree roots. The rotor disk structure
110 includes a rotor disk 114. This rotor disk 114 includes the hub
94, an annular web and an annular counterweight mass, where the web
extends radially out from the counterweight mass to the hub 94.
[0053] The rotor 58 also includes another rotor disk structure 116
as well as one or more linkages 100 and 118. The rotor disk
structure 116 includes the seal element 84 and a rotor disk 120.
This rotor disk 120 includes an annular web and an annular
counterweight mass, where the web extends radially out from the
counterweight mass to the seal element 84. With this configuration,
the seal element (here the seal land 84 in FIG. 3) is configured as
an outer hub/rim of the rotor disk structure 116.
[0054] The seal land 84 is generally axially aligned with and
circumscribes the rotor disk 120. The seal land 84 of FIG. 3
includes an axially extending annular flange with a cylindrical
outer surface 122. Herein, the term "cylindrical" may describe a
surface or part with a circular-annular cross-sectional geometry
which extends substantially (e.g., only) axially along a
centerline. In contrast, a "conical" surface or part may also
extend in a radial direction towards or away from the centerline.
The present disclosure, however, is not limited to the foregoing
seal element configuration as described below with reference to
FIG. 4. In still another embodiment, the seal element may be
configured as a shelf.
[0055] The seal land 84 may be configured having a monolithic full
hoop body. The seal land 84, for example, includes an integral,
tubular body that is formed without any mechanically interconnected
axial and/or circumferential segments. Note, in some embodiments, a
monolithic body may include one or more bodies bonded together. In
another example, arcuate segments (e.g., halves) may be
respectively bonded together to form a full hoop body. The assembly
48 of the present disclosure, however, is not limited to the
foregoing exemplary seal land configuration.
[0056] The upstream linkage 100 may be configured as an annular,
conical linkage. The upstream linkage 100 extends axially between
and is connected to the rotor disk structures 110 and 116. The
upstream linkage 100 may be formed integral with the rotor disk
structures 110 and 116 as shown in FIG. 3. However, in alternative
embodiments, the upstream linkage 100 may be attached (e.g.,
mechanically fastened) to one or both of the rotor disk structures
110 and 116. The present disclosure, however, is not limited to any
particular linkage configuration; e.g., the upstream linkage 100
may alternatively have a cylindrical configuration.
[0057] The downstream linkage 118 may be configured as an annular,
conical linkage. The downstream linkage 118 extends axially between
and is connected to the rotor disk structure 116 and a shaft; e.g.,
the high speed shaft 40. The downstream linkage 118 may be formed
integral with the rotor disk structure 116 as shown in FIG. 3.
However, in alternative embodiments, the downstream linkage 118 may
be attached (e.g., mechanically fastened) to the rotor disk
structure 116. The downstream linkage 118 may be attached (e.g.,
mechanically fastened), or alternatively formed integral with, the
high speed shaft 40. The present disclosure, however, is not
limited to any particular linkage configuration; e.g., the
downstream linkage 118 may alternatively have a cylindrical
configuration.
[0058] The seal assembly 60 is arranged in a radial gap between the
stator structure 54 and the rotor disk structure 116. The seal
assembly 60 is configured to substantially seal the respective gap.
More particularly, the seal assembly 60 is configured to control
(e.g., reduce or substantially eliminate) air leakage between the
stator structure 54 and the rotor disk structure 116. Of course, in
some embodiments, the seal assembly 60 may be configured to allow a
predetermined amount of leakage air to pass thereacross in order to
direct air into the axial gap between the stator structure 54 and
the rotor 58. The seal assembly 60 includes an annular non-contact
seal 78 such as, but not limited to, a hydrostatic non-contact
seal. The seal assembly 60 also may include the seal element. In
the embodiment of FIG. 3, the support structure 82 is configured as
a carrier 206 (see FIG. 5) for the non-contact seal 78.
[0059] Referring to FIGS. 5 to 8, the non-contact seal 78 includes
one or more circumferentially spaced shoes 226 which are located in
a non-contact position along the cylindrical surface of the seal
land 84. Each shoe 226 is formed with a sealing surface 228 and a
slot 230 extending radially inwardly toward the sealing surface
228.
[0060] Under some operating conditions, particularly at higher
pressures, it may be desirable to limit the extent of radial
movement of the shoes 226 with respect to the seal land 84 to
maintain tolerances; e.g., the spacing between the shoes 226 and
the cylindrical surface 128. The non-contact seal 78 includes one
or more circumferentially spaced spring elements 232, the details
of one of which are best seen in FIGS. 7 and 8. Each spring element
232 is formed with an inner band 234 and an outer band 236 radially
outwardly spaced from the inner band 234. One end of each of the
bands 234 and 236 is mounted to or integrally formed with a
stationary base 224 of the seal and the opposite end thereof is
connected to a first stop 238. This base 224 may be configured as a
monolithic full hoop body as best seen in FIG. 5. Of course, the
present disclosure is not limited to the aforesaid exemplary
configuration.
[0061] The first stop 238 includes a strip 240 which is connected
to a shoe 226 (one of which is shown in FIGS. 8 and 9), and has an
arm 242 opposite the shoe 226 which may be received within a recess
244 formed in the base 224. The recess 244 has a shoulder 246
positioned in alignment with the arm 242 of the first stop 238.
[0062] A second stop 248 is connected to or integrally formed with
the strip 240 and is connected to the shoe 226. The second stop 248
is circumferentially spaced from the first stop 238 in a position
near the point at which the inner and outer bands 234 and 236
connect to the base 224. The second stop 248 is formed with an arm
250 which may be received within a recess 252 in the base 224. The
recess 252 has a shoulder 254 positioned in alignment with the arm
250 of second stop 248.
[0063] During operation, aerodynamic forces may be developed which
apply a fluid pressure to the shoe 226 causing it to move radially
with respect to the seal land 84. The fluid velocity increases as
the gap 256 between the shoe 226 and seal land 84 increases, thus
reducing pressure in the gap 256 and drawing the shoe 226 radially
inwardly toward the rotor 58. As the seal gap 256 closes, the
velocity decreases and the pressure increases within the seal gap
256 thus forcing the shoe 226 radially outwardly from the rotor 58.
The spring elements 232 deflect and move with the shoe 226 to
create a primary seal of the circumferential gap 256 between the
rotor 58 and base 224 within predetermined design tolerances. The
first and second stops 238 and 248 may limit the extent of radially
inward and outward movement of the shoe 226 with respect to the
rotor 58 for safety and operational limitation. A gap is provided
between the arm 242 of first stop 238 and the shoulder 246, and
between the arm 250 of second stop 248 and shoulder 254, such that
the shoe 226 can move radially inwardly relative to the rotor 58.
Such inward motion is limited by engagement of the arms 242, 250
with shoulders 246 and 254, respectively, to prevent the shoe 226
from contacting the rotor 58 or exceeding design tolerances for the
gap between the two. The arms 242 and 250 also contact the base 224
in the event the shoe 226 moves radially outwardly relative to the
rotor 58, to limit movement of the shoe 226 in that direction.
[0064] The non-contact seal 78 is also provided with a secondary
seal which may take the form of a brush seal 258, as shown in FIG.
8, or a stack of at least two sealing elements oriented
side-by-side and formed of thin sheets of metal or other suitable
material as shown in FIGS. 9 and 10. The brush seal 258 is
positioned so that one end of its bristles 260 extends into the
slot 230 formed in the shoe 226. The bristles 260 deflect with the
radial inward and outward movement of the shoe 226, in response to
the application of fluid pressure as noted above, in such a way as
to create a secondary seal of the gap 256 between the rotor 58 and
base 224.
[0065] As shown in FIGS. 9 and 10, the secondary seal of this
embodiment may include a stack of at least two sealing elements 262
and 264. Each of the sealing elements 262 and 264 includes an outer
ring 266 formed with a plurality of circumferentially spaced
openings 268, a spring member 270 mounted within each opening 268
and a plurality of inner ring segments 272 each connected to at
least one of the spring members 270. The spring member 270 is
depicted in FIG. 11 as a series of connected loops, but it should
be understood that spring member 270 could take essentially any
other form, including parallel bands as in the spring elements 232.
The sealing elements 262 and 264 are oriented side-by-side and
positioned so that the inner ring segments 272 extend into the slot
230 formed in the shoe 226. The spring members 270 deflect with the
radial inward and outward movement of the shoe 226, in response to
the application of fluid pressure as noted above, in such a way as
to create a secondary seal of the gap 256 between the rotor 58 and
base 224. As such, the sealing elements 272 and 264 assist the
spring elements 232 in maintaining the shoe 226 within design
clearances relative to the rotor 58.
[0066] One or more of the spring elements 262 and 264 may be formed
of sheet metal or other suitable flexible, heat-resistant material.
The sealing elements 262 and 264 may be attached to one another,
such as by welding and/or any other bonding technique, a mechanical
connection or the like, or they may positioned side-by-side within
the slot 230 with no connection between them. In order to prevent
fluid from passing through the openings 268 in the outer ring 266
of each scaling element 262 and 264, adjacent sealing elements are
arranged so that the outer ring 266 of one sealing element 262
covers the openings 268 in the adjacent sealing element 264.
Although not required, a front plate 274 may be positioned between
the spring element 232 and the sealing element 262, and a back
plate 276 may be located adjacent to the sealing element 264 for
the purpose of assisting in supporting the sealing elements 262,
264 in position within the shoe 226.
[0067] During operation, the non-contact seal 78 is subjected to
aerodynamic forces as a result of the passage of air along the
surface of the shoes 226 and the seal land 84. The operation of
non-contact seal 78 is dependent, in part, on the effect of these
aerodynamic forces tending to lift the shoes 226 radially outwardly
relative to the surface of rotor 58, and the counteracting forces
imposed by the spring elements 232 and the secondary seals (e.g.,
brush seal 258 or the stacked seal formed by plates 262, 264) which
tend to urge the shoes 226 in a direction toward the rotor 58.
These forces acting on the shoe 226 are schematically depicted with
arrows in FIG. 11. These forces acting on the non-contact seal 78
may be balanced to ensure that nominal clearance is maintained.
[0068] The present disclosure is not limited to the exemplary
non-contact seal 78 described above. Various other non-contact
seals are known in the art and may be reconfigured in light of the
disclosure above to be included with the assembly 48 of the present
disclosure. Other examples of non-contact seals are disclosed in
U.S. Pat. No. 8,172,232; U.S. Pat. No. 8,002,285; U.S. Pat. No.
7,896,352; U.S. Pat. No. 7,410,173; U.S. Pat. No. 7,182,345; and
U.S. Pat. No. 6,428,009, each of which is hereby incorporated
herein by reference in its entirety. Still another example of a
non-contact seal is a hydrodynamic non-contact seal. Furthermore,
referring to FIG. 4, the seal assembly 60 of the present disclosure
is not limited to including a non-contact seal, but may
alternatively be configured with a contact seal such as, but not
limited to, a knife-edge seal arrangement.
[0069] The assembly 48 may be included in various aircraft and
industrial turbine engines other than the one described above as
well as in other types of rotational equipment; e.g., wind
turbines, water turbines, rotary engines, etc. The assembly 48, for
example, may be included in a geared turbine engine where a gear
train connects one or more shafts to one or more rotors in a fan
section, a compressor section and/or any other engine section.
Alternatively, the assembly 48 may be included in a turbine engine
configured without a gear train. The assembly 48 may be included in
a geared or non-geared turbine engine configured with a single
spool, with two spools (e.g., see FIG. 1), or with more than two
spools. The turbine engine may be configured as a turbofan engine,
a turbojet engine, a propfan engine, a pusher fan engine or any
other type of turbine engine. The present invention therefore is
not limited to any particular types or configurations of turbine
engines or rotational equipment.
[0070] While various embodiments of the present invention have been
disclosed, it will be apparent to those of ordinary skill in the
art that many more embodiments and implementations are possible
within the scope of the invention. For example, the present
invention as described herein includes several aspects and
embodiments that include particular features. Although these
features may be described individually, it is within the scope of
the present invention that some or all of these features may be
combined with any one of the aspects and remain within the scope of
the invention. Accordingly, the present invention is not to be
restricted except in light of the attached claims and their
equivalents.
* * * * *