U.S. patent application number 13/544229 was filed with the patent office on 2014-01-09 for mid-turbine frame hpt seal support meshing.
This patent application is currently assigned to UNITED TECHNOLOGIES CORPORATION. The applicant listed for this patent is Jorge I. Farah, Shu Liu. Invention is credited to Jorge I. Farah, Shu Liu.
Application Number | 20140010649 13/544229 |
Document ID | / |
Family ID | 49878661 |
Filed Date | 2014-01-09 |
United States Patent
Application |
20140010649 |
Kind Code |
A1 |
Farah; Jorge I. ; et
al. |
January 9, 2014 |
MID-TURBINE FRAME HPT SEAL SUPPORT MESHING
Abstract
A seal support comprises a body, a seal carrier disposed
circumferentially around an outer surface of the body, and a
meshing ring extending axially forward of the seal carrier.
Inventors: |
Farah; Jorge I.; (Hartford,
CT) ; Liu; Shu; (South Glastonbury, CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Farah; Jorge I.
Liu; Shu |
Hartford
South Glastonbury |
CT
CT |
US
US |
|
|
Assignee: |
UNITED TECHNOLOGIES
CORPORATION
Hartford
CT
|
Family ID: |
49878661 |
Appl. No.: |
13/544229 |
Filed: |
July 9, 2012 |
Current U.S.
Class: |
415/230 |
Current CPC
Class: |
F01D 25/246 20130101;
F05D 2300/501 20130101; F01D 25/28 20130101; F01D 11/005
20130101 |
Class at
Publication: |
415/230 |
International
Class: |
F01D 25/24 20060101
F01D025/24; F01D 25/00 20060101 F01D025/00 |
Claims
1. A mid-turbine frame for a gas turbine engine, the mid-turbine
frame comprising: a radially outer case; a radially inner case
disposed inward from the radially outer case, the radially outer
and inner cases defining an annular passage therebetween; a
plurality of load spokes extending through the annular passage
securing the outer case with the inner case; and a circumferential
seal support disposed axially forward of the inner case, the
circumferential seal support including a seal carrier and a meshing
ring extending axially forward of the seal carrier.
2. The mid-turbine frame of claim 1, wherein the meshing ring
extends axially toward a pocket formed in a first turbine rotor
assembly, the first turbine rotor assembly disposed upstream of the
mid-turbine frame.
3. The mid-turbine frame of claim 1, wherein the circumferential
seal support is integral with the inner case assembly.
4. The mid-turbine frame of claim 1, wherein the circumferential
seal support is a separately formed seal support and is removably
securable to a forward portion of the inner case.
5. The mid-turbine frame of claim 1, wherein the seal carrier
supports a piston ring seal engaging with an outer wall of a vane
pack disposed in the annular cavity between the outer case and the
inner case.
6. The mid-turbine frame of claim 5, wherein the meshing ring is
disposed closer to a first turbine rotor upstream of the
mid-turbine frame as compared to an axial distance between a
forward end of the vane ring and the turbine rotor immediately
upstream of the mid-turbine frame.
7. The mid-turbine frame of claim 6, wherein the meshing ring
extends into a pocket formed at an aft end of the upstream turbine
rotor.
8. A case assembly comprising: a substantially cylindrical case
element; and a circumferential seal support disposed axially
forward of the inner case, the seal support including a seal
carrier and a meshing ring extending axially forward of the seal
carrier.
9. The case assembly of claim 8, wherein the circumferential seal
support is integral with the inner case assembly.
10. The case assembly of claim 8, wherein the circumferential seal
support is a separately formed seal support and is removably
securable to a forward portion of the inner case.
11. The case assembly of claim 10, wherein the circumferential seal
support has a bulk modulus value lower than a bulk modulus value of
the inner case.
12. The case assembly of claim 8, wherein the meshing ring is
disposed axially adjacent to an adjacent turbine rotor upstream of
the inner case assembly.
13. The case assembly of claim 12, wherein the meshing ring engages
a pocket formed on an aft end of the adjacent turbine rotor.
14. The case assembly of claim 8, wherein the seal carrier is
configured to support a piston ring seal in conjunction with a vane
ring disposed radially adjacent to the case assembly.
15. A seal support comprising: a substantially cylindrical body; a
seal carrier disposed circumferentially around an outer surface of
the body; and a meshing ring extending axially forward of the seal
carrier.
16. The seal support of claim 15, wherein the circumferential seal
support is configured to have a stiffness value in a range between
about 50% to about 80% of a stiffness value of a complementary
inner case element.
17. The seal support of claim 15, wherein the seal support is
formed integrally with an inner case element.
18. The seal support of claim 15, wherein the meshing ring is
disposed axially adjacent to an adjacent turbine rotor upstream of
the seal support.
19. The seal support of claim 18, wherein the meshing ring engages
a pocket formed on an aft end of the adjacent turbine rotor.
20. The seal support of claim 15, wherein the seal carrier is
configured to support a piston ring seal in conjunction with a vane
ring radially outward of the seal support.
Description
BACKGROUND
[0001] The described subject matter relates generally to gas
turbine engines and more particularly, to arrangements for
separating hot and cold flows in gas turbine engines.
[0002] Compact engines require closer packing of components, which
in turn requires more crossing of hot and cold gas flows. Without
adequate thermal protection, seals, and insulation between these
flows, smaller engines suffer from a loss of efficiency. One system
developed for certain engines is the mid-turbine frame (MTF), also
known as the turbine center frame (TCF) or interturbine frame. This
can be disposed between intermediate stages of the turbine section
and can have numerous components serving a variety of functions,
including bearing support, engine backbone, combustion gas flow
path, among others.
[0003] These engine frames support axial, radial, and
circumferential engine loads. In the event of a component failure
in or proximate the MTF, the failure loads should be isolated or
transmitted to other components to reduce the risk of catastrophic
damage.
SUMMARY
[0004] A mid-turbine frame for a gas turbine engine comprises a
radially outer case, a radially inner case, a plurality of load
spokes, and a circumferential seal support. The radially inner case
is disposed inward from the radially outer case defining an annular
passage therebetween. The plurality of load spokes extend through
the annular passage securing the outer case with the inner case.
The circumferential seal support is disposed axially forward of the
inner case, the seal support including a seal carrier and a meshing
ring extending axially forward of the seal carrier.
[0005] A case assembly comprises a substantially cylindrical case
element, and a circumferential seal support disposed axially
forward of the inner case. The seal support includes a seal carrier
and a meshing ring extending axially forward of the seal
carrier.
[0006] A seal support comprises a body, a seal carrier disposed
circumferentially around an outer surface of the body, and a
meshing ring extending axially forward of the seal carrier.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a schematic cross-sectional view of a turbofan gas
turbine engine according to the present description.
[0008] FIG. 2 isometrically depicts an example embodiment of a
mid-turbine frame for a gas turbine engine.
[0009] FIG. 3A shows an exploded isometric view of an example inner
case assembly for the mid-turbine frame depicted in FIG. 2.
[0010] FIG. 3B is a partially cut away cross-sectional view of the
mid-turbine frame of FIG. 2.
[0011] FIG. 4A shows one embodiment of an inner case assembly
relative to an adjacent turbine rotor stage.
[0012] FIG. 4B shows an alternative embodiment of an inner case
assembly relative to an adjacent turbine rotor stage.
DETAILED DESCRIPTION
[0013] FIG. 1 schematically illustrates an example gas turbine
engine 20 that includes fan section 22, compressor section 24,
combustor section 26 and turbine section 28. Alternative engines
might include an augmenter section (not shown) among other systems
or features. Fan section 22 drives air along bypass flow path B
while compressor section 24 draws air in along core flow path G
where air is compressed and communicated to combustor section 26.
In combustor section 26, air is mixed with fuel and ignited to
generate a high pressure exhaust gas stream that expands through
turbine section 28 where energy is extracted and utilized to drive
fan section 22 and compressor section 24.
[0014] Although the disclosed non-limiting embodiment depicts a
turbofan gas turbine engine, it should be understood that the
concepts described herein are not limited to use with turbofans as
the teachings may be applied to other types of turbine engines; for
example a turbine engine including a three-spool architecture in
which three spools concentrically rotate about a common axis and
where a low spool enables a low pressure turbine to drive a fan via
a gearbox, an intermediate spool that enables an intermediate
pressure turbine to drive a first compressor of the compressor
section, and a high spool that enables a high pressure turbine to
drive a high pressure compressor of the compressor section.
[0015] The example engine 20 generally includes low speed spool 30
and high speed spool 32 mounted for rotation about an engine
central longitudinal axis A relative to an engine static structure
34 via several bearing systems 35. It should be understood that
various bearing systems 35 at various locations may alternatively
or additionally be provided.
[0016] Low speed spool 30 generally includes inner shaft 36 that
connects fan 37 and low pressure (or first) compressor section 38
to low pressure (or first) turbine section 39. Inner shaft 36
drives fan 37 through a speed change device, such as geared
architecture 40, to drive fan 37 at a lower speed than low speed
spool 30. High-speed spool 32 includes outer shaft 41 that
interconnects high pressure (or second) compressor section 42 and
high pressure (or second) turbine section 43. Inner shaft 36 and
outer shaft 41 are concentric and rotate via bearing systems 35
about engine central longitudinal axis A.
[0017] Combustor 44 is arranged between high pressure compressor 42
and high pressure turbine 43. In one example, high pressure turbine
43 includes at least two stages to provide a double stage high
pressure turbine 43. In another example, high pressure turbine 43
includes only a single stage. As used herein, a "high pressure"
compressor or turbine experiences a higher pressure than a
corresponding "low pressure" compressor or turbine.
[0018] The example low pressure turbine 39 has a pressure ratio
that is greater than about 5. The pressure ratio of the example low
pressure turbine 39 is measured prior to an inlet of low pressure
turbine 39 as related to the pressure measured at the outlet of low
pressure turbine 39 prior to an exhaust nozzle.
[0019] Mid-turbine frame 46 of engine static structure 34 is
arranged generally between high pressure turbine 43 and low
pressure turbine 46. Mid-turbine frame 46 further supports bearing
systems 35 in turbine section 28 as well as setting airflow
entering low pressure turbine 46.
[0020] The core airflow G is compressed by low pressure compressor
38 then by high pressure compressor 42 mixed with fuel and ignited
in combustor 44 to produce high speed exhaust gases that are then
expanded through high pressure turbine 43 and low pressure turbine
46. Mid-turbine frame 46 includes vanes 58, which are in the core
airflow path and function as an inlet guide vane for low pressure
turbine 39. Utilizing vane 58 of mid-turbine frame 46 as the inlet
guide vane for low pressure turbine 39 decreases the length of low
pressure turbine 39 without increasing the axial length of
mid-turbine frame 46. Reducing or eliminating the number of vanes
in low pressure turbine 39 shortens the axial length of turbine
section 28. Thus, the compactness of gas turbine engine 20 is
increased and a higher power density may be achieved.
[0021] The disclosed gas turbine engine 20 in one example is a
high-bypass geared aircraft engine. In a further example, gas
turbine engine 20 includes a bypass ratio greater than about six
(6), with an example embodiment being greater than about ten (10).
The example geared architecture 40 is an epicyclical gear train,
such as a planetary gear system, star gear system or other known
gear system, with a gear reduction ratio of greater than about
2.3.
[0022] In one disclosed embodiment, gas turbine engine 20 includes
a bypass ratio greater than about ten (10:1) and the fan diameter
is significantly larger than an outer diameter of low pressure
compressor 38. It should be understood, however, that the above
parameters are only exemplary of one embodiment of a gas turbine
engine including a geared architecture and that the present
disclosure is applicable to other gas turbine engines.
[0023] A significant amount of thrust is provided by bypass flow B
due to the high bypass ratio. Fan section 22 of engine 20 is
designed for a particular flight condition--typically cruise at
about 0.8 Mach and about 35,000 feet. The flight condition of 0.8
Mach and 35,000 ft., with the engine at its best fuel
consumption--also known as "bucket cruise Thrust Specific Fuel
Consumption (`TSFC`)"--is the industry standard parameter of
pound-mass (lbm) of fuel per hour being burned divided by
pound-force (lbf) of thrust the engine produces at that minimum
point.
[0024] "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 1.50. In another
non-limiting embodiment the low fan pressure ratio is less than
about 1.45.
[0025] "Low corrected fan tip speed" is the actual fan tip speed in
ft/sec divided by an industry standard temperature correction of
[(T.sub.ram .degree. R)/518.7).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.
[0026] The example gas turbine engine includes fan 37 that
comprises in one non-limiting embodiment less than about 26 fan
blades. In another non-limiting embodiment, fan section 22 includes
less than about 20 fan blades. Moreover, in one disclosed
embodiment low pressure turbine 39 includes no more than about 6
turbine rotors schematically indicated at 33. In another
non-limiting example embodiment low pressure turbine 39 includes
about 3 turbine rotors. A ratio between number of fan blades 37 and
the number of low pressure turbine rotors is between about 3.3 and
about 8.6. The example low pressure turbine 39 provides the driving
power to rotate fan section 22 and therefore the relationship
between the number of turbine rotors at 33 in low pressure turbine
39 and number of blades in fan section 22 disclose an example gas
turbine engine 20 with increased power transfer efficiency.
[0027] FIG. 2 shows MTF 46, and includes outer case 48, outer case
flanges 50A, 50B, inner case assembly 52, vane pack 56, inner vane
pack wall 57A, outer vane pack wall 57B, and vanes 58.
[0028] An example embodiment of MTF 46 has outer case 48 with
axially opposed outer case flanges 50A, 50B for mounting MTF 46 to
adjacent engine component cases (e.g., cases of HPT 43, LPT 39).
Outer case 48 can also be radially secured to inner case assembly
52 to define an engine support frame. In one non-limiting example,
a plurality of radially extending and circumferentially distributed
load spokes (not visible in FIG. 2) structurally join outer case 48
with inner case assembly 52. A forward end of inner case assembly
52 can include one or more seal retention members as described
below to provide at least some convective sealing proximate HPT
section 43, helping to isolate cold and hot gas flows through and
around MTF 46.
[0029] Vane pack 56 operates as a first stage inlet stator for LPT
39 as described above. MTF 46 can be alternatively arranged between
other pairs of adjacent turbine stages. Vane pack 56 is shown here
as having vanes 58 integrally formed monolithic inner and outer
walls 57A, 57B. In certain embodiments, vanes 58 can be removably
secured to one or both walls. Inner and outer walls 57A, 57B can
alternatively be segmented. In embodiments with one or both inner
and outer walls 57A, 57B being segmented, the segments may be
joined together such as by brazing, welding, or other
semi-permanent metal-joining processes. The joints may include
seals or other features to minimize leakage between segments.
[0030] FIG. 3A shows inner case assembly 52 and includes inner case
element 60, circumferential seal support 62, aft seal support
flange 64, complementary case mounting surface 66, seal carrier 68,
seal support body 70, and meshing ring 72.
[0031] FIG. 3A shows an exploded version of one embodiment of inner
case assembly 52. Circumferential seal support 62 is disposed
forward of inner case element 60, and secured via aft seal support
flange 64 or other suitable connecting means to a complementary
mounting surface 66 at a forward end of inner case 60.
Circumferential seal support 62 includes at least one seal
retention member, which in this example is represented by seal
carrier 68 disposed circumferentially around an outer surface of
seal support body 70. Meshing ring 72 is disposed axially forward
of seal carrier 68. When installed as part of MTF 46, meshing ring
72 extends axially toward a pocket formed in an adjacent turbine
rotor assembly, which reduces the distance between the upstream
turbine rotor assembly and the mid-turbine frame as shown in FIGS.
4A-4B. In the event of failure of the rotor assembly, failure loads
are preferentially directed axially through inner case assembly 52
to rather than through vane pack 56 or other more dangerous areas
of MTF 46 as explained below.
[0032] The subject matter is described generally with respect to an
inner case assembly with a separate inner case element removably
securable to the circumferential seal support. In alternate
embodiments, an example of which is shown in FIG. 4B, the
circumferential seal support can be integral with the inner case
element. It should also be noted that circumferential seal support
62 may optionally include other features such as a flow discourager
portion or other ancillary elements falling outside the scope of
this disclosure.
[0033] FIG. 3B shows a partial sectional view of a radially inner
section of MTF 46, and also includes inner case assembly 52, vane
pack 56, inner vane pack wall 57A, vanes 58, inner case element 60,
circumferential seal support 62, aft seal support flange 64,
complementary case mounting surface 66, seal carrier 68, seal
support body 70, meshing ring 72, piston ring seal 74, spoke 76,
and vane pack forward end 78.
[0034] The forward end of inner case assembly 52 can optionally be
sealed to inner vane pack wall 57A proximate HPT 43 (shown in FIG.
1). In this example, seal carrier 68 is configured to retain piston
ring seal 74, which minimizes intrusion of combustion gases from
HPT 43 into the cavity formed between vane pack 56 and inner case
assembly 52. However, the seal assembly may take any suitable
alternative form depending on weight and sealing requirements. Vane
pack 56 can include one or more hollow vanes 58 which also retain
load spokes 76. Spokes 76, in certain embodiments are also hollow
in order to provide cold section flow radially through MTF 46. The
aft end of MTF 46 may be similarly sealed (not shown) to direct
combustion gases into LPT 39. Alternatively, the connection and
seal between MTF 46 and LPT 39 may take any other suitable
form.
[0035] Meshing ring 72 extends forward from seal carrier 68.
Meshing ring 72 causes a forward end of inner case assembly to be
disposed further forward than forward end 78 of vane inner vane
pack wall 57A. As seen below, meshing ring 72 can extend into a
pocket formed into an aft portion of an axially adjacent rotor
assembly, allowing circumferential seal support 62 to be mounted
closer to a first turbine rotor located upstream of MTF 46 as
compared to forward vane pack end 78.
[0036] FIG. 4A shows a forward portion of MTF 46 immediately
downstream of final HPT stage 80, and also includes inner case
assembly 52, inner vane pack wall 57A, vane 58, inner case element
60, circumferential seal support 62, aft seal support flange 64,
complementary case mounting surface 66, seal carrier 68, seal
support body 70, meshing ring 72, piston ring seal 74, vane pack
forward end 78 turbine rotor 80, rotor blade 82, rotor blade root
84, aft rotor disc 86, pocket 88, and aft turbine blade platform
portion 90.
[0037] FIG. 4A includes inner case assembly with separate inner
case element 60 and circumferential seal support 62 secured via
respective flanges 68, 66. As shown above, meshing ring 72 extends
forward from seal carrier 68 toward turbine rotor 80, and is
disposed further forward than inner vane pack forward end 78. In
this example, rotor 80 is the final stage of HPT 43 and includes
rotor blade 82, rotor blade root 84, and aft rotor disc 86. Turbine
rotor 80 can alternatively be any other turbine rotor stage
adjacent to a mid-turbine frame, interturbine frame, or similar
system.
[0038] Meshing ring 72 extends into pocket 88 formed into an aft
portion of turbine rotor 80. Pocket 88 is formed by a radially
outer portion of aft rotor disc 86 and an aft portion of turbine
blade platform 90. Meshing ring 72 causes a forward end of
circumferential seal support 62 to be mounted closer to upstream
turbine rotor 80 as compared to forward vane pack end 78.
[0039] In the unlikely event of failure of turbine rotor 80, at
least some of turbine rotor 80 is pushed axially backward into MTF
46. The failure load is then transmitted axially through inner case
assembly 52 toward the forward rotor stage of LPT 39 (shown in FIG.
1), located immediately downstream of MTF 46. Meshing of HPT 43 and
LPT 39 allows both rotor stages to come gradually to a stop with a
minimum of catastrophic damage such as ruptured oil lines or
bearing supports.
[0040] Other solutions for meshing of HPT 43 with LPT 39 have
involved transmitting the axial failure load through an
interturbine duct, such as vane pack 56. However, there are several
shortcomings to this approach which must be accounted for in
designing other portions of the engine. For example, a rigid
interturbine duct may successfully transmit the failure loads to
the downstream turbine stage. However, this causes the duct to
slide axially relative to support struts and fluid lines that may
pass radially through hollow vanes in the interturbine duct. It has
been suggested to move the interturbine duct forward such that the
struts and fluid lines are not centered in the vane, but this can
cause a weight and structural imbalance in the frame.
[0041] In contrast, meshing ring 72 engages with the rotor disc
pocket 88 soon after failure, which begins to transmit the
resultant loads without axially displacing vane pack 56 and the
attendant risks thereof. In more severe failures, rotor disc 80 may
still transmit some failure loads through vane pack 56, but such
loads are greatly reduced, requiring little or no forward
displacement of vane pack 56 to protect the internal struts and
fluid lines.
[0042] A separate circumferential seal support 62 can be
manufactured from various resilient high-temperature nickel or
cobalt alloys. The alloy used to form circumferential seal support
62 can optionally be manufactured to be more resilient as compared
to inner case element 60. In certain embodiments, circumferential
seal support 62 can be configured to have a lower stiffness in a
range between about 50% to about 80% of the attached inner case
element stiffness, as measured by any suitable test or relevant
industry standard. Lower seal support stiffness can be accomplished
by forming seal support 62 from a structural alloy having a bulk
modulus value in a range between about 50% to about 80% of the
attached inner case element 60 bulk modulus. Alternatively, the
seal support geometry can be tailored to provide a lower stiffness
in a range between about 50% to about 80% of the stiffness of the
complementary inner case element 60. It will also be appreciated
that both the structural alloy and its geometry can both be used in
tandem to configure circumferential seal support 62 with a reduced
stiffness as compared to complementary inner case element 60. This
can allow circumferential seal support 62 to preferentially deform
without rupturing, absorbing some of the axial failure loads while
reducing the total meshing load that must be transmitted axially
toward LPT 39.
[0043] In one illustrative but non-limiting example, the separate
circumferential seal support may be cast or machined from nickel
alloys such as those meeting the requirements of AMS 5663.
Generally speaking, these are alloys containing about 15 wt % to
about 23 wt % chromium, similar in composition to those sold
commercially as Inconel.RTM. 718 and their equivalents. The alloy
can then be heat treated above about 1725.degree. F. (about
940.degree. C.), according to the AMS 5663 specification to result
in a bulk modulus at or above about 30 ksi (about 200 MPa). In
contrast, in certain of these optional embodiments, inner case
element 60 may be a different nickel alloy having a higher bulk
modulus (e.g., at least about 45 ksi or about 300 MPa).
[0044] FIG. 4B shows an alternative embodiment of inner case
assembly 152 immediately downstream of final HPT stage 80, and also
includes inner vane pack wall 57A, vane 58, piston ring seal 74,
vane pack forward end 78, turbine rotor 80, rotor blade 82, rotor
blade root 84, aft rotor disc 86, pocket 88, aft turbine blade
platform portion 90, circumferential seal support portion 160,
inner case portion 162, seal carrier 168, seal support body 170,
and meshing ring 172.
[0045] In this alternative example, inner case assembly 152 is
integrally formed with inner case portion 160 and circumferential
seal support portion 162. Meshing ring 172 engages with the rotor
disc pocket 88 in a manner similar to that described above with
respect to FIG. 4A. However, integral inner case assembly may be
used to simplify the manufacturing process in applications where
the expected meshing loads do not warrant the additional absorption
of meshing loads provided by separate case and seal support
elements.
[0046] While the invention has been described with reference to an
exemplary embodiment(s), 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 invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment(s) disclosed, but that the invention will
include all embodiments falling within the scope of the appended
claims.
Discussion of Possible Embodiments
[0047] The following are non-exclusive descriptions of possible
embodiments of the present invention.
[0048] A mid-turbine frame for a gas turbine engine comprises a
radially outer case, a radially inner case, a plurality of load
spokes, and a circumferential seal support. The radially inner case
is disposed inward from the radially outer case defining an annular
passage therebetween. The plurality of load spokes extend through
the annular passage securing the outer case with the inner case.
The circumferential seal support is disposed axially forward of the
inner case, the seal support including a seal carrier and a meshing
ring extending axially forward of the seal carrier.
[0049] The mid-turbine frame of the preceding paragraph can
optionally include, additionally and/or alternatively, any one or
more of the following features, configurations and/or additional
components.
[0050] A mid-turbine frame for a gas turbine engine according to an
exemplary embodiment of this disclosure includes, among other
possible things, a radially outer case, a radially inner case, a
plurality of load spokes, and a circumferential seal support. The
radially inner case is disposed inward from the radially outer case
defining an annular passage therebetween. The plurality of load
spokes extend through the annular passage securing the outer case
with the inner case. The circumferential seal support is disposed
axially forward of the inner case, the seal support including a
seal carrier and a meshing ring extending axially forward of the
seal carrier.
[0051] A further embodiment of foregoing mid-turbine frame, wherein
the meshing ring extends axially toward a pocket formed in a first
turbine rotor assembly, the first turbine rotor assembly disposed
upstream of the mid-turbine frame.
[0052] A further embodiment of any of the foregoing mid-turbine
frames, wherein the circumferential seal support is integral with
the inner case assembly. A further embodiment of any of the
foregoing mid-turbine frames, wherein the circumferential seal
support is a separately formed seal support and is removably
securable to a forward portion of the inner case. A further
embodiment of any of the foregoing mid-turbine frames, wherein the
seal carrier supports a piston ring seal engaging with an outer
wall of a vane pack disposed in the annular cavity between the
outer case and the inner case. A further embodiment of any of the
foregoing mid-turbine frames, wherein the meshing ring is disposed
closer to a first turbine rotor upstream of the mid-turbine frame
as compared to an axial distance between a forward end of the vane
ring and the turbine rotor immediately upstream of the mid-turbine
frame. A further embodiment of any of the foregoing mid-turbine
frames, wherein the meshing ring extends into a pocket formed at an
aft end of the upstream turbine rotor.
[0053] A case assembly comprises a substantially cylindrical case
element, and a circumferential seal support disposed axially
forward of the inner case. The seal support includes a seal carrier
and a meshing ring extending axially forward of the seal
carrier.
[0054] The case assembly of the preceding paragraph can optionally
include, additionally and/or alternatively, any one or more of the
following features, configurations and/or additional
components.
[0055] A case assembly according to an exemplary embodiment of this
disclosure includes, among other possible things, a substantially
cylindrical case element, and a circumferential seal support
disposed axially forward of the inner case. The seal support
includes a seal carrier and a meshing ring extending axially
forward of the seal carrier.
[0056] A further embodiment of foregoing case assembly, wherein the
circumferential seal support is integral with the inner case
assembly.
[0057] A further embodiment of any of the foregoing case
assemblies, wherein the circumferential seal support is a
separately formed seal support and is removably securable to a
forward portion of the inner case. A further embodiment of any of
the foregoing case assemblies, wherein the circumferential seal
support has a bulk modulus value lower than a bulk modulus value of
the inner case. A further embodiment of any of the foregoing case
assemblies, wherein the meshing ring is disposed axially adjacent
to an adjacent turbine rotor upstream of the inner case assembly. A
further embodiment of any of the foregoing case assemblies, wherein
the meshing ring engages a pocket formed on an aft end of the
adjacent turbine rotor. A further embodiment of any of the
foregoing case assemblies, wherein the seal carrier is configured
to support a piston ring seal in conjunction with a vane ring
disposed radially adjacent to the case assembly.
[0058] A seal support comprises a body, a seal carrier disposed
circumferentially around an outer surface of the body, and a
meshing ring extending axially forward of the seal carrier.
[0059] The seal support of the preceding paragraph can optionally
include, additionally and/or alternatively, any one or more of the
following features, configurations and/or additional
components.
[0060] A seal support according to an exemplary embodiment of this
disclosure includes, among other possible things, a body, a seal
carrier disposed circumferentially around an outer surface of the
body, and a meshing ring extending axially forward of the seal
carrier.
[0061] A further embodiment of the foregoing seal support, wherein
the circumferential seal support is configured to have a stiffness
value in a range between about 50% to about 80% of a stiffness
value of a complementary inner case element. A further embodiment
of any of the foregoing seal supports, wherein the seal support is
formed integrally with an inner case element. A further embodiment
of any of the foregoing seal supports, wherein the meshing ring is
disposed axially adjacent to an adjacent turbine rotor upstream of
the seal support. A further embodiment of any of the foregoing seal
supports, wherein the meshing ring engages a pocket formed on an
aft end of the adjacent turbine rotor. A further embodiment of any
of the foregoing seal supports, wherein the seal carrier is
configured to support a piston ring seal in conjunction with a vane
ring radially outward of the seal support.
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