U.S. patent application number 15/187884 was filed with the patent office on 2016-10-13 for diffusing gas turbine engine recuperator.
The applicant listed for this patent is Pratt & Whitney Canada Corp.. Invention is credited to Daniel ALECU, Andreas ELEFTHERIOU, Darius Jehangir KARANJIA, David MENHEERE.
Application Number | 20160298542 15/187884 |
Document ID | / |
Family ID | 45808179 |
Filed Date | 2016-10-13 |
United States Patent
Application |
20160298542 |
Kind Code |
A1 |
ELEFTHERIOU; Andreas ; et
al. |
October 13, 2016 |
DIFFUSING GAS TURBINE ENGINE RECUPERATOR
Abstract
A method of diffusing and cooling an exhaust flow in an exhaust
duct of a gas turbine engine includes circulating the exhaust flow
from a turbine section of the gas turbine engine to a recuperator
extending within the exhaust duct, circulating air discharged from
a compressor section to a combustor of the gas turbine engine
through air passages of the recuperator, and cooling and diffusing
the exhaust flow by circulating the exhaust flow through exhaust
passages of the recuperator having a progressively increasing
cross-sectional area and in heat exchange relationship with the air
passages.
Inventors: |
ELEFTHERIOU; Andreas;
(Woodbridge, CA) ; MENHEERE; David; (Norval,
CA) ; ALECU; Daniel; (Brampton, CA) ;
KARANJIA; Darius Jehangir; (Mississauga, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Pratt & Whitney Canada Corp. |
Longueuil |
|
CA |
|
|
Family ID: |
45808179 |
Appl. No.: |
15/187884 |
Filed: |
June 21, 2016 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
13036428 |
Feb 28, 2011 |
9395122 |
|
|
15187884 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F28D 21/0003 20130101;
F28D 2021/0026 20130101; F02C 7/10 20130101; F28D 9/0018 20130101;
F05D 2220/32 20130101; F02C 7/08 20130101; F28F 13/08 20130101;
F05D 2260/96 20130101 |
International
Class: |
F02C 7/10 20060101
F02C007/10; F28D 21/00 20060101 F28D021/00; F02C 7/14 20060101
F02C007/14 |
Claims
1. A method of diffusing and cooling an exhaust flow in an exhaust
duct of a gas turbine engine, comprising: circulating the exhaust
flow from a turbine section of the gas turbine engine to a
recuperator extending within the exhaust duct; circulating air
discharged from a compressor section to a combustor of the gas
turbine engine through air passages of the recuperator; and cooling
and diffusing the exhaust flow by circulating the exhaust flow
through exhaust passages of the recuperator having a progressively
increasing cross-sectional area and in heat exchange relationship
with the air passages.
2. The method as defined in claim 1, wherein circulating the
exhaust flow from the turbine section to the recuperator includes
circulating the exhaust flow through passages having a
progressively increasing cross-sectional area and defined by
circumferential splitters of a diffuser located in the exhaust
duct.
3. The method as defined in claim 2, wherein the exhaust flow
circulates through the passages defined by the circumferential
splitters along a path oriented progressively from an axial or
substantially axial direction to a radial or substantially radial
direction.
4. The method as defined in claim 1, wherein circulating the
exhaust flow through the exhaust passages of the recuperator
further includes reducing a swirl the exhaust flow through the
exhaust passages having an arcuate profile in a plane perpendicular
to a central axis of the recuperator.
5. The method as defined in claim 1, further comprising delivering
the exhaust flow from the exhaust passages to atmosphere.
6. The method as defined in claim 1, wherein the progressively
increasing cross-sectional area of the exhaust passages is defined
at least in a curved portion of the exhaust passages.
7. The method as defined in claim 1, wherein cooling the exhaust
flow includes circulating the exhaust flow through the exhaust
passages and circulating the air through the air passages in a
mixed counter flow and double pass cross flow configuration.
8. The method as defined in claim 1, wherein circulating the air
discharged from the compressor section includes circulating the air
through a plenum in fluid flow communication with a discharge of a
compressor of the compressor section and from the first plenum to
the air passages.
9. The method as defined in claim 1, wherein circulating the air to
the combustor includes circulating the air from the air passages to
a plenum containing the combustor.
10. The method as defined in claim 8, wherein the plenum is a first
plenum, and circulating the air to the combustor includes
circulating the air from the air passages to a second plenum
containing the combustor.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 13/036,428 filed Feb. 28, 2011, the entire contents of which
are incorporated by reference herein.
TECHNICAL FIELD
[0002] The application relates generally to a recuperator for a gas
turbine engine and, more particularly, to such a recuperator
allowing for a diffusion of the exhaust flow circulating
therethrough.
BACKGROUND OF THE ART
[0003] Gas turbine engines may include a recuperator, which is a
heat exchanger using hot exhaust gas from the engine to heat the
compressed air exiting the compressor prior to circulation of the
compressed air to the combustion chamber. Preheating the compressed
air usually improves fuel efficiency of the engine. In addition,
the recuperator reduces the heat of exhaust gas, which helps
minimize the infrared signature of the aircraft.
SUMMARY
[0004] In one aspect, there is provided a recuperator configured to
extend within an exhaust duct of a gas turbine engine, the
recuperator comprising exhaust passages providing fluid flow
communication between an exhaust inlet and an exhaust outlet, the
exhaust inlet being oriented to receive exhaust flow from a turbine
of the engine and the exhaust outlet being oriented to deliver the
exhaust flow to atmosphere, the exhaust inlet having a smaller
cross-sectional area than that of the exhaust outlet, and a cross
sectional area of each exhaust passage progressively increasing
from the exhaust inlet to the exhaust outlet such as to diffuse the
exhaust flow, air passages in heat exchange relationship with the
exhaust passages and providing fluid flow communication between an
air inlet and an air outlet, an inlet connection member defining
the air inlet and being designed to sealingly engage a first plenum
in fluid flow communication with a compressor discharge of the gas
turbine engine, and an outlet connection member defining the air
outlet and being designed to sealingly engage a second plenum
containing a compressor of the gas turbine engine.
[0005] In another aspect, there is provided a gas turbine engine
comprising a compressor section having a discharge in fluid flow
communication with a first plenum, a combustor contained in a
second plenum, a turbine section in fluid flow communication with
the combustor, an exhaust duct in fluid flow communication with the
turbine section, and a recuperator located in the exhaust duct, the
recuperator defining: exhaust passages providing fluid flow
communication between an exhaust inlet and an exhaust outlet, the
exhaust inlet and exhaust outlet extending across the exhaust duct
with the exhaust inlet being in fluid flow communication with the
turbine section, the exhaust inlet having a smaller cross-sectional
area than that of the exhaust outlet, and a cross sectional area of
each exhaust passage progressively increasing from the exhaust
inlet to the exhaust outlet such as to diffuse the exhaust flow,
air passages in heat exchange relationship with the exhaust
passages and providing fluid flow communication between an air
inlet and an air outlet, an inlet connection member defining the
air inlet and sealingly engaging the first plenum to receive
pressurized air from the compressor, and an outlet connection
member defining the air outlet and sealingly engaging the second
plenum containing the combustor.
[0006] In a further aspect, there is provided a method of diffusing
and cooling an exhaust flow in an exhaust duct of a gas turbine
engine, comprising circulating the exhaust flow from a turbine
section of the gas turbine engine to a recuperator extending within
the exhaust duct, circulating air discharged from a compressor
section to a combustor of the gas turbine engine through air
passages of the recuperator, and cooling and diffusing the exhaust
flow by circulating the exhaust flow through exhaust passages of
the recuperator having a progressively increasing cross-sectional
area and in heat exchange relationship with the air passages.
DESCRIPTION OF THE DRAWINGS
[0007] Reference is now made to the accompanying figures in
which:
[0008] FIG. 1 is a schematic cross-sectional view of a gas turbine
engine;
[0009] FIG. 2 is a partial cross-sectional view of a gas turbine
engine, showing a recuperator according to a particular
embodiment;
[0010] FIG. 3 is a schematic tridimensional view of a gas turbine
engine including the recuperator of FIG. 2, with one segment
thereof removed;
[0011] FIG. 4 is a tridimensional view of the recuperator of FIG.
2, with one segment thereof omitted;
[0012] FIG. 5 is a tridimensional view of a segment of the
recuperator of FIG. 2;
[0013] FIG. 6 is an exploded tridimensional view of the segment of
FIG. 5;
[0014] FIG. 7 is a partial cross-sectional view of a gas turbine
engine, showing the recuperator of FIG. 2 with a diffuser attached
thereto;
[0015] FIG. 8 is a partial cross-sectional view of a gas turbine
engine, showing a recuperator according to another embodiment;
[0016] FIG. 9 is a tridimensional view of the recuperator of FIG.
8;
[0017] FIG. 10 is a tridimensional view of a segment of the
recuperator of FIG. 8, with a side plate removed;
[0018] FIG. 11 is a schematic cross-sectional view of a floating
connection between the recuperator of FIG. 8 and a plenum of the
gas turbine engine;
[0019] FIG. 12A is a schematic representation of the shape of cold
air cells of the recuperator of FIG. 8; and
[0020] FIG. 12B is a schematic representation of the shape of the
cold air cells of taken along direction B of FIG. 12A.
DETAILED DESCRIPTION
[0021] FIG. 1 illustrates a gas turbine engine 10 of a type
preferably provided for use in subsonic flight, generally
comprising in serial flow communication a fan 12 through which
ambient air is propelled, a compressor section 14 for pressurizing
the air, a combustor 16 in which the compressed air is mixed with
fuel and ignited for generating an annular stream of hot combustion
gases, and a turbine section 18 for extracting energy from the
combustion gases. The compressor section 14 and combustor 16 are
typically in serial flow communication with one another through a
gas generator case 22 which contains the combustor 16 and which
receives the flow from the compressor discharge, which in the
embodiment shown is in the form of diffuser pipes 20. The
combustion gases flowing out of the combustor 16 circulate through
the turbine section 18 and are then expelled through an exhaust
duct 24.
[0022] Although illustrated as a turbofan engine, the gas turbine
engine 10 may alternately be another type of engine, for example a
turboshaft engine, also generally comprising in serial flow
communication a compressor section, a combustor, and a turbine
section, and a propeller shaft supporting a propeller and rotated
by a low pressure portion of the turbine section through a
reduction gearbox.
[0023] Referring to FIG. 2, in the present embodiment, the gas
generator case 22 is separated in at least two plenums, including a
plenum 26 containing the combustor 16, and another plenum 28 in
fluid flow communication with the diffuser pipes 20 of the
compressor section 14.
[0024] A recuperator 30 extends across the exhaust duct 24, such
that the exhaust gas from the turbine section 18 circulates
therethrough. The recuperator 30 also provides the fluid flow
communication between the combustor plenum 26 and the compressor
plenum 28, as will be further detailed below.
[0025] Referring to FIG. 3-6, the recuperator 30 includes a
plurality of arcuate segments 32, which function independently from
one another and are connected to the engine 10 independently from
one another, and which together define the annular shape of the
recuperator 30. A controlled gap 34 (see FIG. 4) is provided
between adjacent ones of the segments 32 to allow for thermal
expansion without interference. In a particular embodiment, the
segments 32 are sized to extend between adjacent structural struts
36 (see FIG. 3) of the engine 10, and as such the gap 34 is sized
to allow for thermal expansion of each segment 32 without major
interference with the strut 36 extending in the gap 34. A
compressible side plate 46 at the side of the segment 32 provides
sealing with the strut 36 and vibrational damping during engine
operation. In the embodiment shown, each segment 32 is sized and
located such as to be removable from the outside of the engine 10
through an opening accessible when the exhaust scroll 38 (see FIG.
2) is removed. With an exhaust scroll 38 that is removable on the
wing, such a configuration allows for the recuperator segments 32
to be removed and replaced if necessary with the engine 10
remaining on the wing.
[0026] Referring particularly to FIGS. 5-6, each segment 32 defines
a plate heat exchanger, with a first group of fluid passages 40 for
circulating the compressed air, and a second group of fluid
passages 42 for circulating the exhaust gas. The air and exhaust
passages 40, 42 alternate and are in heat transfer relationship
with one another. In the embodiment shown, the air and exhaust
passages 40, 42 are relatively oriented such as to define a mixed
counter flow and double pass cross flow heat exchanger. A panel
assembly 44 thus defines the alternating U-shaped first fluid
passages 40 and curved second fluid passages 42. In a particular
embodiment, the panels 44 are made of a nickel alloy and are brazed
to one another. The side plates 46 and a rear bulkhead 48
respectively seal the opposed side ends and the rear end of the
panel assembly 44. The bulkhead 48 also provides vibrational
damping of the segment 32 during engine operation.
[0027] The exhaust fluid passages 42 communicate with a same
exhaust inlet 50 defined by the radially inward end of the segment
32 and with a same exhaust outlet 52 defined by the radially
outward end of the segment 32. The exhaust inlet and outlet 50, 52
extend across the exhaust duct 24, with the exhaust inlet 50
located in proximity of the turbine section 18.
[0028] Referring to FIGS. 5-6, the air passages 40 communicate with
a same air inlet 56 defined at one end thereof and with a same air
outlet 72 defined at the opposed end thereof. The air inlet 56 is
defined by an inlet connection member 58 which is designed to
sealingly engage the compressor plenum 28 for receiving the
compressed air. The air inlet 56 is oriented such that the
compressed air flows axially or approximately axially therethrough.
The inlet connection member 58 includes a duct 60 having one end
connected to an inlet bulkhead 62 attached to the panel assembly
44, and an opposed end having a flange 64 extending outwardly
therearound. Referring to FIG. 2, the inlet connection member 58
also includes a flexible duct member 66 having a first end rigidly
connected to the flange 64, for example through an appropriate type
of fasteners with a compressible seal ring or a gasket (not shown)
therebetween. A second end of the flexible duct member 66 is
rigidly connected to the compressor plenum 28. In the embodiment
shown, the flexible duct member 66 includes two rigid duct portions
68 interconnected by a diaphragm 70, which allows relative movement
between the two duct portions 68; alternately, the entire flexible
duct member 66 may be made of flexible material. Accordingly,
"flexible duct member" is intended herein to designate a duct
member which includes at least a flexible portion such as to allow
for relative movement between its opposed ends. The inlet
connection member 58 thus defines a floating connection with the
compressor plenum 28, such that some amount of axial and radial
relative motion is allowed therebetween.
[0029] Referring back to FIGS. 5-6, the air outlet 72 is defined by
an outlet connection member 74 which is designed to sealingly
engage the combustor plenum 26 for delivering the heated compressed
air to the combustor 16. The air outlet 72 is oriented such that
the heated compressed air flows axially or approximately axially
therethrough. The outlet connection member 74 includes a duct 76
having one end connected to an outlet bulkhead 78 attached to the
panel assembly 44, and an opposed end having a flange 80 extending
outwardly therearound. Referring to FIG. 2, the flange 80 is
rigidly connected to the combustor plenum 26, for example through
an appropriate type of fasteners. A compressible seal ring or a
gasket (not shown) is received between the flanged 80 and the
plenum 26 to form a sealed connection. The outlet connection member
74 thus defines a rigid connection with the combustor plenum
26.
[0030] Alternately, the inlet connection member 58 may define a
rigid connection with the compressor plenum 28, with the outlet
connection member 74 defining a floating connection with the
combustor plenum 26.
[0031] Referring back to FIG. 2, in the embodiment shown, the rear
bulkhead 48 includes a protrusion 82 which is designed to be the
contact point between the segment 32 and the wall 84 of the exhaust
duct 24, in order to stabilize the position of the segment 32
within the exhaust duct 24. The protrusion 82 facilitates the
relative sliding motion between the rear bulkhead 48 and the
exhaust duct wall 84 when relative movement due to the floating
connection occurs, and acts as a control surface maintaining
contact between the segment 32 and the exhaust duct wall 84.
[0032] In a particular embodiment, the exhaust passages 42
including their curved portion have a flaring shape, i.e. the
cross-sectional area of each exhaust passage 42 increases in the
flow direction, from the exhaust inlet 50 to the exhaust outlet 52,
such as to diffuse the exhaust flow. The exhaust inlet 50 thus has
a smaller cross-sectional area than that of the exhaust outlet 52.
Referring particularly to FIG. 2, a concentric split diffuser 53 is
provided in the exhaust duct 24 upstream of the exhaust inlet 50.
The diffuser 53 includes circumferential splitters 54 which are
supported by radial struts 55. The splitters 54 progressively curve
from the axial direction at the upstream end toward the radial
direction. The splitters 54 define passages having a flaring shape,
i.e. with an upstream end having a smaller cross-sectional area
than the downstream end, to diffuse of the exhaust flow further
diffused within the recuperator 30. Diffuser vanes 51 may also be
provided at the exit of the power turbine, upstream of the split
diffuser 53. The diffusion of the exhaust flow allows for an
improved heat exchange within the recuperator 30.
[0033] In the alternate embodiment shown in FIG. 7, the concentric
split diffuser 53' including splitters 53' and radial struts 55'
forms part of the recuperator 30, and extends from the exhaust
inlet 50.
[0034] In a particular embodiment, the recuperator 30 also reduces
the swirl of the exhaust flow. As can be seen from FIG. 4, the
exhaust passages 42 have an arcuate profile in a plane
perpendicular to a central axis C of the recuperator to reduce the
exhaust flow swirl. The splitters 54 (FIG. 2) may also be curved in
the plane perpendicular to the central axis of the recuperator. The
radial struts 55, 55' which are structural members supporting the
splitters 54, 54' (FIGS. 2 and 7) have an asymmetrical airfoil
shape twisted to allow a progressively increased swirl with
increasing radius, optimised to reduce the turning losses as the
flow turns from the axial to the radial direction within the
diffuser 53, 53'. The vanes 51 may also have an asymmetrical
airfoil shape similar to the struts 55, 55'. The swirl, i.e. the
circumferential component of the flow velocity at the power turbine
exit, is thus first slowed in the diffuser vanes 51. The flow
exiting the vanes 51 enter the split diffuser 53, 53'. The flow in
the split diffuser 53, 53' slows down both in the axial direction
due to the splitters 54, 54' as well as in circumferential
direction, i.e. the swirl, due to the increased radius of the
swirling shape of the radial struts 55, 55'.
[0035] Referring now to FIGS. 8-12, a recuperator 130 according to
an alternate embodiment is shown. The recuperator 130 includes a
plurality of independent arcuate segments 132, with a controlled
gap 134 being defined between adjacent segments 132 for thermal
expansion. Each segment 132 defines a plate heat exchanger, with a
first group of fluid passages 140 for circulating the compressed
air, and a second group 142 of fluid passages for circulating the
exhaust gas, alternating and in heat transfer relationship with one
another.
[0036] The recuperator 130 extends within the exhaust duct 24
closer to the turbine section 18 than the previously described
embodiment. Each segment 132 includes an exhaust inlet 150 defined
by a radially extending end of the segment 132 located in proximity
of the turbine section 18 and in communication with the exhaust
passages 142. The exhaust inlet 150 is oriented such that the
exhaust gas flows axially or approximately axially therethrough.
Each segment 132 also includes an exhaust outlet 152 in
communication with exhaust passages 142, and oriented such that the
exhaust gas flows outwardly radially or approximately outwardly
radially therethrough.
[0037] The air passages 140 communicate with a same air inlet 156
defined at one end thereof and with a same air outlet 172 defined
at the opposed end thereof. The air inlet 156 is defined by an
inlet connection member 158 which is designed to sealingly engage
the compressor plenum 28 for circulating the compressed air. The
air inlet 156 is oriented such that the compressed air flows
axially or approximately axially therethrough. The inlet connection
member 158 includes a support 164 surrounding the inlet 156 which
is rigidly connected to the compressor plenum 28, for example
through an appropriate type of fasteners with a compressible seal
ring or a gasket (not shown) therebetween. The inlet connection
member 158 thus defines a rigid connection with the compressor
plenum 28.
[0038] The air outlet 172 is defined by an outlet connection member
174 which is designed to sealingly engage the combustor plenum 26
for delivering the heated compressed air to the combustor 16. The
air outlet 172 is oriented such that the heated compressed air
flows radially outwardly or approximately radially outwardly
therethrough. The outlet connection member 174 includes a duct 176
which is engaged in a corresponding opening of the combustor plenum
26. Referring to FIG. 11, a flexible and compressible circular seal
94, for example having a C-shaped cross-section, surrounds the duct
176 and abuts the wall 98 of the plenum 26 around the opening where
the duct 176 is received. A collar 92, sandwiched between retaining
rings 90, is received between the seal 94 and an outwardly
extending flange 96 of the duct 176, and compresses the seal 94.
The connection member 174 thus defines a floating connection with
the combustor plenum 26, as some amount of axial and tangential
relative motion is allowed between the connection member 174 and
the support opening of the plenum 26 to compensate for thermal
mismatch. The circular seal 94 seals the connection.
[0039] As can be seen in FIG. 8 and FIG. 12B, the exhaust passages
142 defined between the air cells 141 forming the air passages 140,
including the curved portion of each exhaust passage 142, have a
flaring shape such as to diffuse the exhaust flow. The exhaust
inlet 150 thus has a smaller cross-sectional area than that of the
exhaust outlet 152. The diffusion of the exhaust flow allows for an
improved heat exchange within the recuperator 130. In the
embodiment shown, the recuperator 130 has a shape substantially
confirming to that of the exhaust duct 24, with a controlled gap
134 (see FIG. 11) being provided between the recuperator 130 and
exhaust duct wall to prevent restriction of the relative movement
allowed by the floating connection.
[0040] In a particular embodiment, the recuperator 130 also reduces
the swirl of the exhaust flow. As can be seen from FIGS. 9 and 12B,
the air cells 141 forming the exhaust passages 142 act as vanes,
and have an arcuate profile in a plane perpendicular to a central
axis C of the recuperator to reduce the exhaust flow swirl. The air
cells 141 thus define a diffusion area 99 and a deswirling and
diffusion area 100, which act to slow down the exhaust flow both in
the axial direction as well as in circumferential direction.
[0041] In the above described embodiments, each segment 32, 132 of
the recuperator 30, 130 is only connected to the engine 10 through
the inlet and outlet connection members 58, 158, 74, 174, and the
segments 32, 132 are independent from each other. Since one of
these connection members defines a floating connection, some
relative movement is allowed between each segment 32, 132 of the
recuperator 30, 130 and the remainder of the gas turbine engine 10,
such as to accommodate some amount of thermal expansion without
impeding the seal of the connections.
[0042] The above description is meant to be exemplary only, and one
skilled in the art will recognize that changes may be made to the
embodiments described without departing from the scope of the
invention disclosed. Modifications which fall within the scope of
the present invention will be apparent to those skilled in the art,
in light of a review of this disclosure, and such modifications are
intended to fall within the appended claims.
* * * * *