U.S. patent application number 16/410049 was filed with the patent office on 2020-11-19 for brush secondary seal for cantilevered hydrostatic advanced low leakage seal.
The applicant listed for this patent is United Technologies Corporation. Invention is credited to Eric A. Grover, Daniel L. Gysling, Brian F. Hilbert, John P. Virtue.
Application Number | 20200362714 16/410049 |
Document ID | / |
Family ID | 1000004127184 |
Filed Date | 2020-11-19 |
United States Patent
Application |
20200362714 |
Kind Code |
A1 |
Hilbert; Brian F. ; et
al. |
November 19, 2020 |
BRUSH SECONDARY SEAL FOR CANTILEVERED HYDROSTATIC ADVANCED LOW
LEAKAGE SEAL
Abstract
A hydrostatic seal configured to be disposed between relatively
rotatable components includes a seal carrier. The seal also
includes a beam extending axially from a forward end to an aft end,
the beam cantilevered to the seal carrier at one of the forward end
and the aft end, the beam free at the other end. The seal further
includes a brush seal operatively coupled to the seal carrier and
in contact with the beam.
Inventors: |
Hilbert; Brian F.;
(Coventry, CT) ; Gysling; Daniel L.; (South
Glastonbury, CT) ; Virtue; John P.; (Middletown,
CT) ; Grover; Eric A.; (Tolland, CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
United Technologies Corporation |
Farmington |
CT |
US |
|
|
Family ID: |
1000004127184 |
Appl. No.: |
16/410049 |
Filed: |
May 13, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F05D 2240/56 20130101;
F01D 11/08 20130101; F01D 11/001 20130101; F01D 1/04 20130101; F16J
15/3268 20130101 |
International
Class: |
F01D 11/00 20060101
F01D011/00; F01D 11/08 20060101 F01D011/08 |
Claims
1. A hydrostatic seal configured to be disposed between relatively
rotatable components, the seal comprising: a seal carrier; a beam
extending axially from a forward end to an aft end, the beam
cantilevered to the seal carrier at one of the forward end and the
aft end, the beam free at the other end; and a brush seal
operatively coupled to the seal carrier and in contact with the
beam.
2. The seal of claim 1, wherein the beam includes a flange
extending radially outwardly into a region at least partially
defined by the seal carrier and the beam, the brush seal in contact
with the flange.
3. The seal of claim 2, wherein the flange extends perpendicular to
the axial direction of the beam.
4. The seal of claim 3, wherein the brush seal extends axially.
5. The seal of claim 3, wherein the brush seal extends
radially.
6. The seal of claim 2, wherein bristles of the brush seal are in
contact with a forward face of the flange.
7. The seal of claim 2, wherein the flange is oriented at an angle
between parallel and perpendicular to a radially outer surface of
the beam.
8. The seal of claim 7, wherein the brush seal is oriented at an
angle that is perpendicular to the flange.
9. The seal of claim 1, wherein the beam is cantilevered to the
seal carrier at the forward end of the beam.
10. The seal of claim 1, wherein the beam is cantilevered to the
seal carrier at the aft end of the shoe.
11. The seal of claim 1, wherein the brush seal is in contact with
the beam proximate the end of the beam that is free.
12. A seal assembly disposed in a gas turbine engine, the seal
assembly comprising: a stator; a rotor; and a first hydrostatic
seal disposed between the stator and the rotor, the seal
comprising: a seal carrier; a beam extending axially from a forward
end to an aft end, the beam cantilevered to the seal carrier at one
of the forward end and the aft end, the beam free at the other end,
the beam including a flange extending radially outwardly into a
region at least partially defined by the seal carrier and the beam;
and a brush seal operatively coupled to the seal carrier and in
contact with the flange of the beam.
13. The seal assembly of claim 12, wherein the flange extends
perpendicular to the axial direction of the beam.
14. The seal assembly of claim 13, wherein the brush seal extends
axially.
15. The seal assembly of claim 13, wherein the brush seal extends
radially.
16. The seal assembly of claim 12, wherein bristles of the brush
seal are in contact with a forward face of the flange.
17. The seal assembly of claim 12, wherein the flange is oriented
at an angle between parallel and perpendicular to a radially outer
surface of the beam.
18. The seal assembly of claim 17, wherein the brush seal is
oriented at an angle that is perpendicular to the flange.
19. A gas turbine engine comprising: a compressor section; a
combustor section; a turbine section; and a seal assembly disposed
in the gas turbine engine, the seal assembly comprising a stator, a
rotor, and a first hydrostatic seal disposed between a stator and
the rotor, the seal comprising: a seal carrier; a beam extending
axially from a forward end to an aft end, the beam cantilevered to
the seal carrier at the aft end, the beam free at the forward end,
the beam including a flange extending radially outwardly into a
region at least partially defined by the seal carrier and the beam;
and a brush seal operatively coupled to the seal carrier and in
contact with a forward face of the flange of the beam.
20. The gas turbine engine of claim 19, wherein the brush seal
extends at an angle between 0 and 90 degrees relative to the
forward face of the flange.
Description
BACKGROUND
[0001] Exemplary embodiments pertain to the art of gas turbine
engines and, more particularly, to a brush secondary seal for a
cantilevered hydrostatic seal.
[0002] Hydrostatic seals exhibit less leakage compared to
traditional knife edge seals while exhibiting a longer life than
brush seals. Some hydrostatic seals may be used between a stator
and a rotor within a gas turbine engine. The hydrostatic seal is
mounted to the stator to maintain a desired gap dimension between
the hydrostatic seal and the rotor. The hydrostatic seal has the
ability to `track` the relative movement between the stator and the
rotor throughout the engine operating profile when a pressure
differential is developed across the seal.
[0003] Hydrostatic seals involve motion of a spring-attached shoe
with a response based on aerodynamic forces developed between the
seal shoe and a rotor surface during operation. The hydrostatic
seals include one or more secondary seals loaded against a free end
of the shoe, and possibly other structural components of the
overall seal assembly. The need for reliable secondary sealing
options is recognized for hydrostatic seals, particularly those
with a cantilevered shoe. Such seals include compliant beam
elements that are separated by gaps. Reducing leakage across these
gaps to avoid a potentially significant performance penalty is
desirable.
BRIEF DESCRIPTION
[0004] Disclosed is a hydrostatic seal configured to be disposed
between relatively rotatable components. The seal includes a seal
carrier. The seal also includes a beam extending axially from a
forward end to an aft end, the beam cantilevered to the seal
carrier at one of the forward end and the aft end, the beam free at
the other end. The seal further includes a brush seal operatively
coupled to the seal carrier and in contact with the beam.
[0005] In addition to one or more of the features described above,
or as an alternative, further embodiments may include that the beam
includes a flange extending radially outwardly into a region at
least partially defined by the seal carrier and the beam, the brush
seal in contact with the flange.
[0006] In addition to one or more of the features described above,
or as an alternative, further embodiments may include that the
flange extends perpendicular to the axial direction of the
beam.
[0007] In addition to one or more of the features described above,
or as an alternative, further embodiments may include that the
brush seal extends axially.
[0008] In addition to one or more of the features described above,
or as an alternative, further embodiments may include that the
brush seal extends radially.
[0009] In addition to one or more of the features described above,
or as an alternative, further embodiments may include that bristles
of the brush seal are in contact with a forward face of the
flange.
[0010] In addition to one or more of the features described above,
or as an alternative, further embodiments may include that the
flange is oriented at an angle between parallel and perpendicular
to a radially outer surface of the beam.
[0011] In addition to one or more of the features described above,
or as an alternative, further embodiments may include that the
brush seal is oriented at an angle that is perpendicular to the
flange.
[0012] In addition to one or more of the features described above,
or as an alternative, further embodiments may include that the beam
is cantilevered to the seal carrier at the forward end of the
beam.
[0013] In addition to one or more of the features described above,
or as an alternative, further embodiments may include that the beam
is cantilevered to the seal carrier at the aft end of the shoe.
[0014] In addition to one or more of the features described above,
or as an alternative, further embodiments may include that the
brush seal is in contact with the beam proximate the end of the
beam that is free.
[0015] Also disclosed is a seal assembly disposed in a gas turbine
engine. The seal assembly includes a stator. The seal assembly also
includes a rotor. The seal assembly further includes a first
hydrostatic seal disposed between the stator and the rotor. The
seal includes a seal carrier. The seal also includes a beam
extending axially from a forward end to an aft end, the beam
cantilevered to the seal carrier at one of the forward end and the
aft end, the beam free at the other end, the beam including a
flange extending radially outwardly into a region at least
partially defined by the seal carrier and the beam. The seal
further includes a brush seal operatively coupled to the seal
carrier and in contact with the flange of the beam.
[0016] In addition to one or more of the features described above,
or as an alternative, further embodiments may include that the
flange extends perpendicular to the axial direction of the
beam.
[0017] In addition to one or more of the features described above,
or as an alternative, further embodiments may include that the
brush seal extends axially.
[0018] In addition to one or more of the features described above,
or as an alternative, further embodiments may include that the
brush seal extends radially.
[0019] In addition to one or more of the features described above,
or as an alternative, further embodiments may include that bristles
of the brush seal are in contact with a forward face of the
flange.
[0020] In addition to one or more of the features described above,
or as an alternative, further embodiments may include that the
flange is oriented at an angle between parallel and perpendicular
to a radially outer surface of the beam.
[0021] In addition to one or more of the features described above,
or as an alternative, further embodiments may include that the
brush seal is oriented at an angle that is perpendicular to the
flange.
[0022] Further disclosed is a gas turbine engine including a
compressor section, a combustor section, a turbine section, and a
seal assembly disposed in the gas turbine engine, the seal assembly
comprising a stator, a rotor, and a first hydrostatic seal disposed
between a stator and the rotor. The seal includes a seal carrier.
The seal also includes a beam extending axially from a forward end
to an aft end, the beam cantilevered to the seal carrier at the aft
end, the beam free at the forward end, the beam including a flange
extending radially outwardly into a region at least partially
defined by the seal carrier and the beam. The seal further includes
a brush seal operatively coupled to the seal carrier and in contact
with a forward face of the flange of the beam.
[0023] In addition to one or more of the features described above,
or as an alternative, further embodiments may include that the
brush seal extends at an angle between 0 and 90 degrees relative to
the forward face of the flange.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The following descriptions should not be considered limiting
in any way. With reference to the accompanying drawings, like
elements are numbered alike:
[0025] FIG. 1 is a side, partial cross-sectional view of a gas
turbine engine;
[0026] FIG. 2 is a side, elevational, cross-sectional view of a
hydrostatic seal assembly according to an aspect of the
disclosure;
[0027] FIG. 3 is a side, elevational, cross-sectional view of the
hydrostatic seal assembly according to another aspect of the
disclosure; and
[0028] FIG. 4 is a side, elevational, cross-sectional view of the
hydrostatic seal assembly according to another aspect of the
disclosure.
DETAILED DESCRIPTION
[0029] A detailed description of one or more embodiments of the
disclosed apparatus and method are presented herein by way of
exemplification and not limitation with reference to the
Figures.
[0030] FIG. 1 schematically illustrates a gas turbine engine 20.
The gas turbine engine 20 is disclosed herein as a two-spool
turbofan that generally incorporates a fan section 22, a compressor
section 24, a combustor section 26 and a turbine section 28. The
fan section 22 drives air along a bypass flow path B in a bypass
duct, while the compressor section 24 drives air along a core flow
path C for compression and communication into the combustor section
26 then expansion through the turbine section 28. Although depicted
as a two-spool turbofan gas turbine engine in the disclosed
non-limiting embodiment, it should be understood that the concepts
described herein are not limited to use with two-spool turbofans as
the teachings may be applied to other types of turbine engines
including three-spool architectures.
[0031] The exemplary engine 20 generally includes a low speed spool
30 and a high speed spool 32 mounted for rotation about an engine
central longitudinal axis A relative to an engine static structure
36 via several bearing systems 38. It should be understood that
various bearing systems 38 at various locations may alternatively
or additionally be provided, and the location of bearing systems 38
may be varied as appropriate to the application.
[0032] The low speed spool 30 generally includes an inner shaft 40
that interconnects a fan 42, a low pressure compressor 44 and a low
pressure turbine 46. The inner shaft 40 is connected to the fan 42
through a speed change mechanism, which in exemplary gas turbine
engine 20 is illustrated as a geared architecture 48 to drive the
fan 42 at a lower speed than the low speed spool 30. The high speed
spool 32 includes an outer shaft 50 that interconnects a high
pressure compressor 52 and high pressure turbine 54. A combustor 56
is arranged in exemplary gas turbine 20 between the high pressure
compressor 52 and the high pressure turbine 54. An engine static
structure 36 is arranged generally between the high pressure
turbine 54 and the low pressure turbine 46. The engine static
structure 36 further supports bearing systems 38 in the turbine
section 28. The inner shaft 40 and the outer shaft 50 are
concentric and rotate via bearing systems 38 about the engine
central longitudinal axis A which is collinear with their
longitudinal axes.
[0033] The core airflow is compressed by the low pressure
compressor 44 then the high pressure compressor 52, mixed and
burned with fuel in the combustor 56, then expanded over the high
pressure turbine 54 and low pressure turbine 46. The turbines 46,
54 rotationally drive the respective low speed spool 30 and high
speed spool 32 in response to the expansion. It will be appreciated
that each of the positions of the fan section 22, compressor
section 24, combustor section 26, turbine section 28, and fan drive
gear system 48 may be varied. For example, gear system 48 may be
located aft of combustor section 26 or even aft of turbine section
28, and fan section 22 may be positioned forward or aft of the
location of gear system 48.
[0034] The engine 20 in one example is a high-bypass geared
aircraft engine. In a further example, the engine 20 bypass ratio
is greater than about six (6), with an example embodiment being
greater than about ten (10), the geared architecture 48 is an
epicyclic gear train, such as a planetary gear system or other gear
system, with a gear reduction ratio of greater than about 2.3 and
the low pressure turbine 46 has a pressure ratio that is greater
than about five. In one disclosed embodiment, the engine 20 bypass
ratio is greater than about ten (10:1), the fan diameter is
significantly larger than that of the low pressure compressor 44,
and the low pressure turbine 46 has a pressure ratio that is
greater than about five (5:1). Low pressure turbine 46 pressure
ratio is pressure measured prior to inlet of low pressure turbine
46 as related to the pressure at the outlet of the low pressure
turbine 46 prior to an exhaust nozzle. The geared architecture 48
may be an epicycle gear train, such as a planetary gear system or
other gear system, with a gear reduction ratio of greater than
about 2.3:1. It should be understood, however, that the above
parameters are only exemplary of one embodiment of a geared
architecture engine and that the present disclosure is applicable
to other gas turbine engines including direct drive turbofans.
[0035] A significant amount of thrust is provided by the bypass
flow B due to the high bypass ratio. The fan section 22 of the
engine 20 is designed for a particular flight condition--typically
cruise at about 0.8 Mach and about 35,000 feet (10,688 meters). The
flight condition of 0.8 Mach and 35,000 feet (10,688 meters), with
the engine at its best fuel consumption--also known as "bucket
cruise Thrust Specific Fuel Consumption (`TSFC`)"--is the industry
standard parameter of 1 bm of fuel being burned divided by 1 bf of
thrust the engine produces at that minimum point. "Low fan pressure
ratio" is the pressure ratio across the fan blade alone, without a
Fan Exit Guide Vane ("FEGV") system. The low fan pressure ratio as
disclosed herein according to one non-limiting embodiment is less
than about 1.45. "Low corrected fan tip speed" is the actual fan
tip speed in ft/sec divided by an industry standard temperature
correction of [(Tram .degree. R)/(518.7.degree. R)].sup.0.5. The
"Low corrected fan tip speed" as disclosed herein according to one
non-limiting embodiment is less than about 1150 ft/second (350.5
m/sec).
[0036] FIG. 2 illustrates a hydrostatic seal indicated generally at
100. The hydrostatic seal 100 is intended to create a seal between
two relatively rotating components, such as a fixed stator and a
rotating rotor 102. The hydrostatic seal 100 includes a carrier 107
and a beam 108, which is located in a non-contact position along
the exterior surface of the rotor 102. The beam 108 is formed with
a sealing surface 110. For purposes of the present disclosure, the
term "axial" or "axially spaced" refers to a direction along the
rotational axis of the rotor, whereas "radial" refers to a
direction perpendicular to the rotational axis of the rotor.
[0037] Rather than relying on the structural stiffness of the beam
108, the embodiments described herein include a cantilevered beam
as the beam 108. Therefore, the beam 108 is connected to the
carrier 107 of the seal 100 in a pinned manner or some suitable
alternative mechanical fastener that allows pivoting movement of
the beam 108, relative to the carrier 107. The carrier 107 is fixed
to a static structure (not shown). In the illustrated embodiments,
the beam 108 is pinned (i.e., cantilevered) to the carrier 107 at a
rear axial end 114 of the beam 108, while a forward axial end 116
of the beam 108 is free and not operatively coupled to any other
structure. The carrier 107 includes a first segment 109 extending
radially, a second segment 111 extending axially forward from the
first segment 109, and a third segment 113 extending radially
inwardly away from the second segment 111 toward the rotor 102.
[0038] In the illustrated embodiment, the rear axial end 114 of the
beam 108 is cantilevered to the first segment 109 of the carrier
107 to form a substantially open front end. However, it is to be
appreciated that the beam 108 is operatively connected to the
carrier 107 at an opposite end of the beam 108. In particular, the
front end 116 of the beam 108 is pinned, or otherwise cantilevered,
to the carrier 107 in some embodiments, with the front end 116
connected to the third segment 113 of the carrier 107.
[0039] The initial assembly location of the beam 108 has a defined
radial gap between the beam 108 and the rotating surface. One or
more teeth 118 are included on the sealing surface 110 of the beam
108. In operation, as the airflow between the beam 108 and rotor
102 increases, the pressure field under the teeth 118 will be
dropped to a lower pressure than the exit pressure in a region aft
of the teeth 118. The reduction in pressure across the beam 108
causes a net aerodynamic force acting on the beam 108 such that the
force balance between the aerodynamic forces on the outer diameter
121 of the beam 108 and the inner diameter, i.e., sealing surface
110, causes the beam 108 to be moved radially inwardly toward the
rotor 102, thus decreasing the gap until the seal reaches an
equilibrium position considering the increased structural force of
the displaced cantilevered beam. Conversely, in operation, when the
gap closes below a desired level, the aerodynamic force on the
sealing surface 110 across the beam 108 increases, causing an
increase in radial pressure force, which overcomes the force on the
outer diameter 121, thus forcing the beam 108 radially outwardly
from the rotor 102 until the seal reaches an equilibrium position
considering the structural force of the displaced cantilevered
beam. The cantilevered beam 108 deflects and moves to create a
primary seal of the gap between the rotor and stator within
predetermined design tolerances.
[0040] The cantilevered seals described herein are more robust to
wear, when compared to prior hydrostatic seals that have contact
between stationary and moving components that, due to friction, can
cause the shoe to become fully or partially pinned in place, and be
unable to avoid contact with the rotor during a transient maneuver.
In prior hydrostatic seals, large normal loads developed at
operating conditions are reacted at a sliding interface between the
shoe and carrier backing plate. The cantilevered seals provide a
way of transmitting axial forces in a manner independent of the
shoe radial motion, as the differential pressure is reacted through
the cantilever. The seals described herein are designed to
eliminate rotor contact. Frictional loads are difficult to
characterize and can change over the life of the seal and lead to
flutter. The cantilevered seals described herein avoid such
problems.
[0041] The embodiments disclosed herein include a secondary seal in
the form of a brush seal 122 is provided proximate the free end of
the beam 108 (i.e., closer to the free end than the secured end of
the beam). In the illustrated embodiments, the free end is the
axially forward end 116, but the reverse may be true, as described
above in detail. It is to be appreciated that some embodiments are
contemplated to include more brush seals to define a brush seal
assembly or only one brush seal. For purposes of descriptive
brevity, a single brush seal is described herein. The brush seal
122 provides a seal between the illustrated high pressure region
126 and the low pressure region 128 in a space radially outward of
the beam 108.
[0042] In the illustrated embodiments, a flange 130 of the beam 108
extends radially outwardly from the beam 108 into the low pressure
region 128 at least partially defined by the beam 108 and the
carrier 107. Abase 132 of the brush seal 122 is secured to the
third segment 113 of the carrier 107, with bristles 134 of the
brush seal 122 in contact with the flange 130 to provide a seal. In
the illustrated embodiment of FIG. 2, the brush seal 122 is
oriented substantially axially (i.e., direction along the
rotational axis of the rotor), such that the bristles 134 of the
brush seal 122 extend substantially perpendicular to a forward face
136 of the flange 130. Although illustrated and described as having
the brush seal 122 in contact with the flange 130, it is
contemplated that the brush seal 122 is in contact with the axially
forward end 116 itself in some embodiments.
[0043] Other orientations of the brush seal 122 are contemplated.
For example, as shown in FIG. 3, the flange 130 and the brush seal
122 may be angled relative to the illustrated orientations of FIG.
2. In particular, the brush seal 122 may be secured to the second
segment 111 or the third segment 113 of the carrier 107 and
oriented at an angle that is between perpendicular and parallel to
the axial and radial directions, as defined herein. In such an
embodiment, the flange 130 is angled between parallel and
perpendicular to the rotational axis of the rotor to allow the
brush seal 122 to extend substantially perpendicular to the forward
face 136 of the flange 130, with the bristles 134 in contact
therewith. It is to be appreciated that any angle between 0 and 90
degrees is contemplated.
[0044] FIG. 4 illustrates another angular orientation of the brush
seal 122. In particular, the brush seal 122 is secured to the
second portion 111 of the carrier 107 and extend substantially
radially. The flange 130 extends substantially perpendicularly. The
bristles 134 extend radially inwardly to an extent sufficient to
contact the forward face 136 of the flange 130.
[0045] The brush seals 122 utilized as the secondary seals herein
are provided at the free end of the cantilevered beam 108 to reduce
leakage. Although cantilevered seals may be aerodynamically stable,
the brush seal 122 provides the benefit of additional mechanical
damping. Additionally, the overall cantilevered seal and brush seal
assembly has less friction that "conventional" hydrostatic seal
assemblies. The brush seal 122 provides enough friction to dampen
an aerodynamic instability without affecting seal operability.
[0046] The term "about" is intended to include the degree of error
associated with measurement of the particular quantity based upon
the equipment available at the time of filing the application. For
example, "about" can include a range of .+-. 8% or 5%, or 2% of a
given value.
[0047] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the present disclosure. As used herein, the singular forms "a",
"an" and "the" are intended to include the plural forms as well,
unless the context clearly indicates otherwise. It will be further
understood that the terms "comprises" and/or "comprising," when
used in this specification, specify the presence of stated
features, integers, steps, operations, elements, and/or components,
but do not preclude the presence or addition of one or more other
features, integers, steps, operations, element components, and/or
groups thereof.
[0048] While the present disclosure has been described with
reference to an exemplary embodiment or embodiments, it will be
understood by those skilled in the art that various changes may be
made and equivalents may be substituted for elements thereof
without departing from the scope of the present disclosure. In
addition, many modifications may be made to adapt a particular
situation or material to the teachings of the present disclosure
without departing from the essential scope thereof. Therefore, it
is intended that the present disclosure not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this present disclosure, but that the present
disclosure will include all embodiments falling within the scope of
the claims.
* * * * *