TECHNICAL FIELD
The present invention relates generally to heat
exchangers in turbo fan gas turbine engines and, more
specifically, to heat exchangers and regulating flow
in fan bypass ducts of the engines.
BACKGROUND INFORMATION
At least some known aircraft gas turbine engines
include a fan, a compressor, a combustor, a high
pressure turbine, a low pressure turbine, and an
augmentor or "afterburner" and an exhaust nozzle.
The compressor, combustor, high pressure turbine, and
low pressure turbine are collectively referred to as
a core engine or engine core.
Airflow entering the fan is compressed. Airflow
exiting the fan is split such that a portion of the
flow referred to as core engine flow is directed into
the compressor and the remaining portion of the
airflow, referred to as fan bypass flow, is directed
into a bypass duct or passage where it bypasses the
compressor, the combustor, the high pressure turbine,
and the low pressure turbine. Airflow entering the
compressor is compressed and directed to the
combustor where it is mixed with fuel and ignited,
producing hot combustion gases used to drive both the
high pressure and the low pressure turbines.
Moreover, at least some known gas turbine engines
combine a portion of the fan bypass flow with the
airflow exiting the low pressure turbine forming an
exhaust flow. The exhaust flow may be further heated
in the augmentor before exiting through the exhaust
nozzle .
Variable cycle or variable bypass gas turbine
engines have been designed to combine high thrust
capabilities of turbo ets with good fuel efficiency
of turbofan engines. Typically in variable cycle
engines the amount of air that is bypassed is
changed to suit aircraft speed.
The bypass air is often modulated or regulated
by various devices for various reasons. To regulate
an amount of bypass air supplied to the augmentor, at
least some gas turbine engines include a valve
assembly. More specifically, in some known gas
turbine engines, the fan bypass flow is regulated
based on specific exhaust liner pressure ratio
requirements demanded for the type of flight mode of
the aircraft.
Variable cycle systems have been considered for
use in typical military engines that use augmentors
(afterburners) to provide additional thrust at
supersonic speeds. Afterburning turbofan engines
typically utilize mixers that take part of the
engine's bypass air and mix or inject that air into
the core engine flow in an engine s afterburning
section. Typically, it is desirable to increase the
total bypass flow at dry operating conditions and to
reduce the bypass flow at augmented conditions.
Under dry conditions, the object is to improve
specific fuel consumption and during augmented
conditions, the object is to improve thrust.
Rear Variable Area Bypass Injectors (rear
VABI's) are used to inject the bypass air at the
afterburner and forward Variable Area Bypass
Injectors (forward VABI's) are used to inject or
control bypass air flowing into the fan bypass duct.
Some examples of such VABI's are described in
various U.S. Patents including U.S. Pat. No.
4,069,661; U.S. Pat. No. 4,064,692; U.S. Pat. No.
4,072,008; U.S. Pat. No. 4,010,608; U.S. Pat. No.
4,068,471, and U.S. Pat. No. 4,175,384.
VABI 's and other types of valves used to
regulate an amount of bypass air supplied to the
augmentor may include a plurality of adjustable or
variable blocker doors or variable vanes. Variable
vanes disposed in fan ducts of aircraft high bypass
gas turbine engines and FLADE engines are two
examples of such an apparatus. U.S. Pat. No.
7,758,303, issued July 10, 2010, entitled "FLADE Fan
With Different Inner And Outer Airfoil Stagger Angles
At A Shroud Therebetween" discloses a variable FLADE
inlet guide vanes disposed in a FLADE duct which
surrounds a core engine. U.S. Pat. No. 4,080,785,
issued March 28, 1978, entitled "Modulating bypass
variable cycle turbofan engine" discloses flaps at
downstream ends of fan bypass ducts for variable area
fan nozzles. U.S. Pat. No. 7,721,549, issued May 25,
2010, entitled "Fan variable area nozzle for a gas
turbine engine fan nacelle with cam drive ring
actuation system" discloses a fan variable area
nozzle including a flap assembly which varies a fan
nozzle exit area. U.S. Pat. No. 4,292,802, issued
October 6 , 1981, entitled "Method and apparatus for
increasing compressor inlet pressure" discloses a
plurality of blocker door vanes disposed in the
bypass duct to selectively close off the bypass flow
and increase the flow and pressure of the air flowing
into the compressor.
Two regulating valves are disclosed in U.S. Pat.
Application Serial Nos. 11/753,929, filed May 25,
2007, entitled "METHOD AND APPARATUS FOR REGULATING
FLUID FLOW THROUGH A TURBINE ENGINE" and 11/753,907,
filed May 25, 2007, entitled "TURBINE ENGINE VALVE
ASSEMBLY AND METHOD OF ASSEMBLING THE SAME". These
regulating valves includes an outer fairing coupled
to a radially outer duct wall, an inner fairing
coupled to a radially inner duct wall, and a
translatable annular slide valve. The annular slide
valve is selectively positioned between the fairings
such that at least one flow area between the slide
valve and the fairings is varied. The VABI's,
variable vanes, and other types of valves are
referred to herein as variable geometry flow
restrictor .
Modern gas turbine engines and variable cycle
engines require cooling air or other fluids for the
hot components such as turbine components and
aircraft avionics. Other type of heat exchangers
found in gas turbine engines are used for cooling
oil, fuel and water. This cooling air or fluid often
requires a heat exchanger to transfer energy into the
bypass of the engine and the heat exchanger is often
located in the bypass duct or uses bypass duct
airflow. Variable cycle engines can provide large
efficiency and performance boosts over a large range
of power requirements. The VABI's and blockers,
generally referred to herein as bypass valves, have
been developed for turbofan aircraft engines to take
advantage of these benefits.
Heat exchangers in the bypass duct and bypass
valves often conflict with one another, especially if
they use the same air. Heat exchangers restrict
airflow and hurt the engine performance benefit of a
variable geometry engine an engine using bypass
valves) . Variable geometry often restricts the heat
exchangers flow when it is needed most.
Accordingly, it is desired to provide a gas
turbine engine having a heat exchanger cooled by fan
bypass flow and a bypass valve for regulating or
restricting the fan bypass flow. It is further
desired to have low or reduced performance conflicts
between the heat exchanger and bypass valve.
BRIEF DESCRIPTION OF THE INVENTION
An integrated variable geometry flow restrictor
and heat exchanger system (1) includes one or more
heat exchangers (8) mounted in a duct 3 ), heat
transfer cooling passages (9) in each of the heat
exchangers (8), and a variable geometry flow
restrictor (2) integral with each of the heat
exchangers (8) .
The system may further include a variable area
(4) between the heat exchangers (8) and one of inner
and outer casings (36, 34) bounding the duct (3) and
an annular slide valve (102) axially translatable
within the duct (3) and with respect to the heat
exchanger (8) and operable to open and close or vary
the variable area (4). The heat exchangers (8) may
be mounted to one of the inner and outer casings (36,
34) . The duct (3) may be annular, circumscribed
about a longitudinal centerline (11), and the heat
exchangers (8) circumferential ly distributed around
the duct (3) . The heat exchangers {8) may include
radial or circumferential ly curved heat transfer
tubes (6) or vanes.
The heat exchangers (8) may include an annular
upstream row of tube and fin heat exchangers (170)
rotatable and/or axially translatable with respect to
an annular downstream row of tube and fin heat
exchangers (172) . The annular upstream and
downstream rows of tube and fin heat exchangers (170,
172) further include radially extending upstream and
downstream heat transfer tubes (174, 176)
respectively. The annular upstream and downstream
rows of tube and fin heat exchangers (170, 172)
operate as the variable geometry flow restrictor (2)
for opening and closing a variable area (4) between
the upstream and downstream heat transfer tubes (174,
176) . The duct (3) may be annular and circumscribed
about a longitudinal centerline (11) and the annular
upstream and downstream rows of tube and fin heat
exchangers (170, 172) may be annular segments
disposed about the longitudinal centerline (11) .
The heat exchangers (8) may further include an
annular array (180) of hollow vanes (182) and the
variable geometry flow restrictor (2) may include
variable leading edge tips (184) for opening and
closing a variable area (4) between the hollow vanes
(182).
A gas turbine engine (10) circumscribed about a
longitudinal centerline (11) includes an annular
inlet (12) followed in axial downstream flow
relationship by a fan assembly (16), a high pressure
compressor (20), a combustor (22), a high pressure
turbine (24), and a low pressure turbine (26). An
outer casing (34) radially spaced apart from an inner
casing (36) define a bypass duct (40) therebetween.
The bypass duct (40) is located around and radially
outwardly of the high pressure compressor (20), the
combustor (22), the high pressure turbine (24), and
the low pressure turbine (26) . An integrated
variable geometry flow restrictor and heat exchanger
system (1) includes one or more heat exchangers (8)
mounted in the duct (40) and a variable geometry flow
restrictor (2) integral with the heat exchangers (8) .
Heat transfer cooling passages (9) are in each of
the heat exchangers (8).
The variable geometry flow restrictor (2) may
include at least one slide valve assembly (100)
disposed in the bypass duct (40) and the heat
transfer cooling passages (9) may be carried by one
or more components (102, 128, 130) of the slide valve
assembly (100) . The components of the slide valve
assembly (100) may include at least one of inner and
outer fairings (128, 130) and an axially translatable
annular slide valve (102) within the bypass duct
(40) . The slide valve (102) is operable to open and
close or vary the variable area (4) which is bounded
by the one of the inner and outer fairings (128,
130) .
The variable area (4) may include an inner
bypass cross-sectional area (150) between the slide
valve (102) and the inner fairing (128) and an outer
bypass cross-sectional area (160) between the slide
valve (102) and the outer fairing (130) . An annular
slide valve (102) axially translatable within the
bypass duct (40) and with respect to the heat
exchanger (8) is operable to open and close or vary a
variable area (4) between the heat exchanger (8) and
one of inner and outer casings (36, 34) bounding the
bypass duct (40).
A gas turbine engine (410) may have a fan (429)
with a longitudinally aft-most row of generally
radially outwardly extending fan blades (430) and the
bypass duct (447) extends axially aftwardly and
downstream from the fan (429) to a fan nozzle (442)
at a longitudinally aft end (439) of the fan bypass
duct (447). An annular row of hollow variable-pitch
fan outlet guide vanes (452) are radially disposed
across the fan bypass duct (447) longitudinally aft
of the fan (429) . The heat transfer cooling passages
(9) include the hollow variable-pitch fan outlet
guide vanes (452) operable for passing cooling air
therethrough and the variable geometry flow
restrictor (2) includes the hollow variable-pitch fan
outlet guide vanes (452) being pivotable about pivot
axes (453) normal to the engine centerline (412) .
Vane leading or trailing edges (455, 457) of the
variable-pitch fan outlet guide vanes (452) may be
pivotable .
A gas turbine engine (410) may include a fan
(429) having a longitudinally aft-most row of
generally radially outwardly extending fan blades
(430) in the fan assembly (16), a bypass duct (447)
extending axially aftwardly and downstream from the
fan (429) to a fan nozzle (442) at a longitudinally
aft end (439) of the fan bypass duct (447), a
variable geometry flow restrictor (2) including a
circumferential row of pivotal flaps (473) disposed
in the fan nozzle (442), and heat transfer cooling
passages (9) carried by the circumferential row of
pivotal flaps 3 ).
A gas turbine engine (10) may have a variable
area exhaust nozzle (29) axially aft and downstream
of the low pressure turbine (26), an exhaust flow
path (555) radially surrounded by the inner casing
(36) and extending downstream from the low pressure
turbine (26), and a variable area bypass injector
(550) generally radially located between the bypass
duct (40) and the exhaust flow path (555) and axially
located aft and downstream of the low pressure
turbine (26) . A variable geometry flow restrictor
(2) of the variable area bypass injector (550)
includes a slider valve (560) operable to selectively
cover one or more openings (562) in the inner casing
(36) between the bypass duct (40) and the exhaust
flow path (555) and the heat transfer cooling
passages (9) include one or more heat transfer tubes
(6) disposed in each of the openings (562).
Impingement holes (570) or slots in the slider valve
(560) may be aimed to direct an injection portion
(553) of fan bypass flow (48) in the bypass duct (40)
to impinge directly onto the heat transfer tubes (6)
when the slider valve (560) is in a closed position.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an axial diagrammatical view
illustration of an integrated variable geometry flow
restrictor and heat exchanger system in a gas turbine
engine fan bypass duct with the restrictor in an open
position.
FIG. 2 is an axial sectional diagrammatical view
illustration of the system illustrated in FIG. 1 with
the restrictor in a closed position.
FIG. 3 is an axial sectional diagra mat al view
illustration of a segmented integrated variable
geometry flow restrictor and heat exchanger system in
a gas turbine engine fan bypass duct.
FIG. 3A is a diagrammatical planform view
illustration of the segmented integrated variable
geometry flow restrictor and heat exchanger system
illustrated in FIG. 3 .
FIG. 4 is an axial sectional diagrammatical view
illustration of a heat exchanger illustrated in FIG.
4 with radial heat transfer tubes or vanes.
FIG. 5 is an axial sectional diagrammatical view
illustration of a heat exchanger illustrated in FIG.
4 with radial heat transfer tubes or vanes.
FIG. 6 is an axial sectional schematic view
illustration of an exemplary variable cycle turbine
engine with a first exemplary embodiment of the
integrated variable geometry flow restrictor and heat
exchanger system illustrated in FIG. 1 .
FIG. 7 is an enlarged axial sectional schematic
view illustration of the integrated variable geometry
flow restrictor and heat exchanger system illustrated
in FIG. 6 in an open position.
FIG. 8 is an enlarged axial sectional schematic
view illustration of the integrated variable geometry
flow restrictor and heat exchanger system illustrated
in FIG. 6 in a closed position.
FIG. 9 is a radially inwardly looking planform
schematic view illustration of an integrated variable
geometry flow restrictor and heat exchanger system
including upstream and downstream tube and fin heat
exchangers that can rotate and/or translate axially
with respect to each other in an open position.
FIG. 10 is a radially inwardly looking planforra
schematic view illustration of the integrated
variable geometry flow restrictor and heat exchanger
system illustrated in FIG. 9 with the restrictor in a
closed position.
FIG. 11 is a radially inwardly looking planform
schematic view illustration of an integrated variable
geometry flow restrictor and heat exchanger system
including hollow vanes with variable leading edge
tips in an open position.
FIG. 12 is a radially inwardly looking planform
schematic view illustration of the integrated
variable geometry flow restrictor and heat exchanger
system illustrated in FIG. 11 with the restrictor in
a closed position.
FIG. 13 is an axial sectional schematic view
illustration of an exemplary high bypass turbofan
engine with variable-pitch fan outlet guide vanes
incorporating another exemplary embodiment of an
integrated variable geometry flow restrictor and heat
exchanger system.
FIG. 14 is a radially inwardly looking planform
schematic view illustration of the vanes in FIG. 13
in an open position.
FIG. 15 is a radially inwardly looking planform
schematic view illustration of the vanes in FIG. 13
in a closed position.
FIG. 16 is an axial sectional schematic view
illustration of an exemplary high bypass turbofan
engine with a fan nozzle including pivotal flaps
incorporating another exemplary embodiment of an
integrated variable geometry flow restrictor and heat
exchanger system.
FIG. 17 is an axial sectional schematic view
illustration of an integrated variable geometry flow
restrictor and heat exchanger system having heat
transfer tubes in an outlet of a rear variable area
bypass injector (VABI) .
DETAILED DESCRIPTION OF THE INVENTION
An integrated variable geometry flow restrictor
and heat exchanger system 1 in a gas turbine engine
annular fan bypass duct 3 circumscribed about a
longitudinal centerline 11 is illustrated in FIGS. 1
and 2 . An outer casing 34 radially spaced apart from
an inner casing 36 bounds the fan bypass duct 3 . The
integrated variable geometry flow restrictor and heat
exchanger system 1 illustrated in FIGS. 1 and 2
includes a heat exchanger 8 integral and in parallel
flow relationship with a variable geometry flow
restrictor 2 .
The heat exchanger 8 is illustrated herein as
being mounted on the inner casing 36 but
alternatively may be mounted on the outer casing 34
or radially between the casings. The variable
geometry flow restrictor 2 is illustrated in an open
position in FIG. 1 and in a closed position in FIG.
2 . The flow restrictor 2 is illustrated as including
an annular slide valve 102 axially translatable with
respect to the heat exchanger 8 and operable to open
and close or vary a variable area 4 between the heat
exchanger 8 and the outer casing 34 in the bypass
duct 3 .
The heat exchangers 8 illustrated herein are air
to air heat exchngers to cool cooling air. Other
type of air to fluid heat exhangers are contemplated.
Such air to fluid heat exhangers include heat
exchangers used for cooling oil, fuel and water.
The heat exchanger 8 provides good heat transfer
performance tailored to the needs of engine
components cooled by the heat exchanger at both high
and low bypass operation. The high and low bypass
operation corresponds to the flow restrictor 2 being
in opened and closed positions as illustrated in
FIGS. 1 and 2 respectively. The heat exchanger 8
also does not overly restricts bypass flow 5 in the
bypass duct 3 during low power and high bypass flight
operating conditions of the engine, thus, allowing
for larger bypass ratios, higher thrust, and better
SFC as compared to previous designs.
A heat exchanger's effectiveness will vary when
placed in series with a flow control device (i.e.
variable bypass area injector or flow restrictor) as
is done in the prior art. The heat exchanging
effectiveness is often low when the bypass ratio is
low and high when the bypass ratio is high in
variable bypass variable cycle engines. Engine
performance reacts in the opposite manner because of
high-pressure loss at high flow. This results in a
trade-off being made by designers with respect to
heat exchanger effectiveness vs. engine performance.
When the engine is at high power, the fan bypass
flow is often restricted. At high power, the engine
and aircraft need the most cooling and the heat
exchanger's performance is low because of low fan
bypass flow. At low power, the cooling requirements
are minimal but the heat exchanger acts as a large
resistor in the bypass flow and acts to reduce engine
thrust and performance. The integrated variable
geometry flow restrictor and heat exchanger system 1
in a gas turbine engine annular fan bypass duct 3
disclosed herein avoids these consequences because
the variable geometry flow restrictor and heat
exchanger are in parallel flow relationship with the
bypass flow 5 in the fan bypass duct 3 .
Illustrated in FIGS. 3 and 3A is an exemplary
circumferential distribution or arrangement of four
heat exchangers 8 and four variable geometry flow
restrictors 2 that may be used in the gas turbine
engine annular fan bypass duct 3 for the integrated
variable geometry flow restrictor and heat exchanger
system 1 described above. The heat exchangers 8 and
the variable geometry flow restrictors 2 are shaped
in annular segments. Each of the annular variable
geometry flow restrictors 2 is circumferentially
disposed between two circumferentially adjacent heat
exchangers 8 .
Two exemplary embodiments of the heat exchangers
include circumferentially curved heat transfer tubes
6 or vanes used for heat transfer in the heat
exchangers 8 as illustrated in FIG. 4 and radial heat
transfer tubes 7 or vanes as illustrated in FIG. 5 .
The tubes illustrated herein are only examples of
heat transfer cooling passages 9 that may be used in
the heat exchangers 8 .
Illustrated in FIGS. 6 and 7 is an exemplary
variable cycle gas turbine engine 10 having a
longitudinal centerline 11. The engine 10 includes
an annular inlet 12 for receiving ambient air 14
followed in axial downstream flow relationship by a
fan assembly 16, a high pressure compressor (HPC) 20,
a combustor 22, a high pressure turbine (HPT) 24, a
low pressure turbine (LPT) 26, an augmentor 28, and
variable area exhaust nozzle 29. The HPT 24 powers
the HPC 20 through a first shaft 30. The LPT 26
powers the fan assembly 16 by a second shaft 32.
Engine 10 further includes an outer casing 34 which
is radially spaced apart from an inner casing 36
including a forward section 38 of inner casing 36
defining a bypass duct 40 therebetween. The
augmentor 28 includes a liner 42.
At least one slide valve assembly 100 disposed
in the bypass duct 40 serves as the variable geometry
flow restrictor. One or more components of the valve
assembly 100 carry heat exchanger heat transfer tubes
6 and, thus, serve as the heat exchanger 8 in the
integrated variable geometry flow restrictor and heat
exchanger system 1 . Specifically, engine 10 includes
a plurality of valve assemblies 100 positioned
circumferentially within duct 40. More specifically,
the valve assembly 100 is positioned to facilitate
separating bypass duct 40 into a radially inner
bypass duct 44 and a radially outer bypass duct 46.
In the exemplary embodiment of the engine 10,
fan bypass flow 48 entering bypass duct 40 is divided
into an inner air flow 50 and an outer air flow 52.
The valve assembly 100 facilitates regulating the
amount of inner air flow 50 that is channeled through
inner bypass duct 44 and the amount of outer air flow
52 that is channeled through outer bypass duct 46.
The engine and its operation are described in more
detail in United States Patent Application Serial No.
11/753,907, by Donald Michael Corsmeier et al., filed
May 25, 2007, entitled "TURBINE ENGINE VALVE ASSEMBLY
AND METHOD OF ASSEMBLING THE SAME", assigned to the
General Electric Company, the assignee of this
patent, and hereby incorporated by reference.
Referring further to FIG. 7 , components of the
valve assembly 100 illustrated herein include an
annular slide valve 102 that is slidably coupled
within bypass duct 40 via an exemplary crank assembly
200. Slide valve 102 includes a radially inner
surface 108 and a radially outer surface 110. The
radially inner surface 108 converges gradually from a
valve forward end referred to herein as a valve nose
112 in a downstream direction or aftwardly. The
radially outer surface 110 converges gradually from
the valve nose 112 in a downstream direction or
aftwardly. The valve nose 112 is shaped to
facilitate splitting fan bypass flow 48 while
reducing its separation.
Valve assembly 100 includes an inner fairing 128
and an outer fairing 130 that is positioned
downstream from inner fairing 128. The outer fairing
130 is positioned proximate radially outer casing 34
and inner fairing 128 is positioned proximate
radially inner casing 36. One or more of the slide
valve 102 and inner and outer fairings 128, 130 carry
the heat exchanger heat transfer tubes 6 which denote
a heat exchanger 8 . All three components are
illustrated herein as carrying the heat exchanger
heat transfer tubes 6 and, thus, serving as a
variable geometry flow restrictor 2 .
In the exemplary embodiment, outer fairing 130
and inner fairing 128 are coupled together via a
strut 158 and translate axially together between
outer casing 34 and inner casing 36. The annular
slide valve 102 extends between inner fairing 128 and
outer fairing 130. Moreover, in the exemplary
embodiment, inner fairing 128 and outer fairing 130
are each contoured such that inner bypass duct 44 and
outer bypass duct 46 each have variable
cross-sectional areas.
The inner and outer fairings 128, 130 are
operable to slide substantially simultaneously within
the bypass duct 40. The valve assembly 100 is
coupled to at least one crank assembly 200 which
controls the axial translation of the slide valve
102, outer fairing 130, inner fairing 128, and strut
158. The crank assembly 200 moves slide valve 102,
and inner and outer fairings 128, 130 between first
and second operational positions 300, 302. The first
and second operational positions 300, 302 correspond
to the variable geometry flow restrictor being opened
and closed as illustrated in FIGS. 7 and 8
respectively.
When the valve assembly 100 is in the first
position 300, an inner bypass cross-sectional area
150 is defined between valve 102 and inner fairing
128, and an outer bypass cross-sectional area 160 is
defined between valve 102 and outer fairing 130. The
valve 102 is in a first operational position, such
that substantially all of fan bypass flow 48 is
channeled downstream into the inner bypass duct 44
and the outer bypass duct 46. The fan bypass flow 48
is separated into inner air flow 50 and outer air
flow 52. The inner air flow 50 flows through inner
bypass duct 44, the outer air flow 52 flows through
outer bypass duct 46, and the inner air flow 50 flows
into augmenter 28 through the diffuser liner 42.
As valve assembly 100 is moved towards position
304, the inner bypass cross-sectional area 150 is
reduced to an inner bypass duct cross-sectional area
151 and outer bypass cross-sectional area 160 is
reduced to an outer bypass duct cross-sectional area
161. Reducing cross-sectional areas 150, 160 of each
duct 44, 46 reduces an amount of airflow that may be
channeled through ducts 44, 46 and closes down the
areas within the duct. Specifically, when valve
assembly 100 is in second operational position 302, a
substantial portion of fan bypass flow 48 is
prevented from entering inner bypass duct 44 and/or
outer bypass duct 46. As such, fan bypass flow 48
may be channeled to other outlets (not shown) , such
as, for example, roll post nozzles that facilitate
vertical lift of the aircraft. The remaining fan
bypass flow 48 is divided into inner air flow 50 and
outer air flow 52. Inner air flow 50 is channeled
through inner bypass duct 44 and outer air flow 52 is
channeled through outer bypass duct 46. In the
exemplary embodiment, the inner air flow 50 flows
into augmenter 28 through dif fuser liner 4 .
At low power engine, cooling requirements are
minimal as is the cooling flow 51 through the heat
exchanger when inner air flow 50 flows into the
augmenter 28 through the diffuser liner 42. At high
power, the engine cooling requirements are
substantially greater as is the cooling flow 51
through the heat exchanger such as during takeoff and
vertical lift of the aircraft.
Illustrated in FIGS. 9 and 10 is another
exemplary integrated variable geometry flow
restrictor and heat exchanger system 1 located in a
fan bypass duct 3 . The system includes annular
upstream and downstream rows of tube and fin heat
exchangers 170, 172 that can rotate and/or translate
axially with respect to each other. The annular
upstream and downstream rows of tube and fin heat
exchangers 170, 172 include radially extending
upstream and downstream heat transfer tubes 174, 176
respectively that serve as the variable geometry flow
restrictor 2 for opening and closing a variable area
4 between the upstream and downstream heat transfer
tubes 174, 176.
Though illustrated in a flat planform view
herein the upstream and downstream rows of tube and
fin heat exchangers 170, 172 are shaped in annular
segments about the longitudinal centerline 11 similar
to the view illustrated in FIG. 3 . FIGS. 9 and 10
illustrate the variable geometry flow restrictor 2 in
open and closed positions respectively.
Illustrated in FIGS. 11 and 12 is an exemplary
integrated variable geometry flow restrictor and heat
exchanger system 1 including an annular array 180 of
hollow vanes 182 with variable leading edge tips 184
circumferentially disposed about the longitudinal
centerline 11 of the fan bypass duct 3 . The leading
edge tips 184 are operably disposed in the fan bypass
duct 3 for rotating about the longitudinal centerline
11 and with respect to the non-rot atable hollow vanes
182. The leading edge tips 184 serve as the variable
geometry flow restrictor 2 for opening and closing a
variable area 4 between adjacent hollow vanes.
Cooling air is circulated through the hollow vanes
182 which serve as the heat exchanger. The hollow
vanes 182 with variable leading edge tips 184 may be
in annular segments about the longitudinal centerline
11 similar to the view illustrated in FIG. 3 .
Illustrated in FIG. 13 is an exemplary bypass
turbofan gas turbine engine 410 having an engine
centerline 412 and including a core engine 414 having
a high pressure compressor 416, a combustor 418, and
a high pressure turbine 420, all arranged in a serial
axial flow relationship. A low pressure or power
turbine 424 is downstream of and powered by the core
engine 414 and drives an interconnected low pressure
compressor 428 and a fan 429. The fan 429 includes a
longitudinally aft-most row of generally radially
outwardly extending fan blades 430.
The core engine 414, the low pressure turbine
424, and the low pressure compressor 428 are
surrounded by a casing or core nacelle 432 disposed
longitudinally aft and downstream of the fan blades
430. The core nacelle 432 includes a longitudinally
forward end defining a flow splitter 434 and a
longitudinally aft end defining a core exhaust nozzle
436. A fan nacelle 438 circumferential y surrounds
the fan blades 430 and extends along at least a
portion of the core nacelle 432. The fan nacelle 438
is supported about the core nacelle 432 by a
plurality of support members such as fan frame struts
440. It is noted blades and vanes have cambered
airfoil shapes while struts do not.
The fan nacelle 438 includes a fan nozzle 442,
an inner exterior surface 444 facing generally
radially inward, and an outer exterior surface 446
facing generally radially outward. An annular fan
bypass duct 447 radially disposed between the fan
nacelle 438 and the core nacelle 432 extends axially
aftwardly or downstream from the flow splitter 434 to
the fan nozzle 442. The fan nozzle 442 is located at
a longitudinally aft end 439 of the fan bypass duct
447. An annular row of variable-pitch fan outlet
guide vanes 452 is radially disposed across the fan
bypass duct 447 between the fan and core nacelles
438, 432 and longitudinally aft of the flow splitter
434.
The variable-pitch fan outlet guide vanes 452,
as illustrated in FIGS. 14 and 15, are hollow and
operable to pass cooling air therethrough so that the
row of variable-pitch fan outlet guide vanes 452
serves as a heat exchanger 8 . The variable -pitch fan
outlet guide vanes 452 are illustrated herein as
being pivotable about pivot axes 453 that are normal
to the engine centerline 412. Alternatively, vane
pitch could be varied by having only a vane leading
edge 455 or a vane trailing edge 457 of the
variable-pitch fan outlet guide vanes 452 being
pivotable or by otherwise varying the effective angle
of incidence of the vanes, as is known to those
skilled in the art. Thus, the row of variable-pitch
fan outlet guide vanes 452 also serves as a variable
geometry flow restrictor 2 for opening and closing a
variable area 4 between circumferentially adjacent
variable-pitch fan outlet guide vanes 452. The row
of hollow variable-pitch fan outlet guide vanes 452
serve as the integrated variable geometry flow
restrictor and heat exchanger system 1 . FIGS. 14 and
15 illustrate the integrated variable geometry flow
restrictor 2 which are the hollow variable-pitch fan
outlet guide vanes 452 in open and closed positions
respectively.
Other types of variable-pitch vanes may also be
used as the integrated variable geometry flow
restrictor and heat exchanger system 1 . For example
a circumferential row of variable-pitch vanes 462
used in the high pressure compressor 20 of engine 10
illustrated in FIG. 6 could also be hollow and
constructed to serve as a heat exchanger 8 and
variable geometry flow restrictor 2 . The
variable-pitch vanes 462 extend radially across a
high pressure compressor flowpath 464 in a core
engine duct 466 of the core engine which includes the
high pressure compressor 20. A circumferential row
of hollow variable-pitch vanes may also be used in
the low pressure compressor 428 of engine 10
illustrated in FIG. 13. The variable-pitch vanes
could also be hollow and constructed to serve as a
heat exchanger 8 and variable geometry flow
restrictor 2 in the low pressure compressor 428.
Illustrated in FIG. 16 is an exemplary bypass
turbofan gas turbine engine 410 disposed about an
engine centerline 412 similar to the engine
illustrated in FIG. 13 without the variable-pitch fan
outlet guide vanes. A fan nacelle 438
circumferentially surrounds the fan blades 430 and
extends along at least a portion of a core nacelle
432. The fan nacelle 438 is supported about the core
nacelle 432 by a plurality of support members such as
fan frame struts 440.
A variable area fan nozzle 442 is located at a
longitudinally aft end of the fan nacelle 438. The
fan nacelle 438 has an inner exterior surface 444
facing generally radially inward and an outer
exterior surface 446 facing generally radially
outward. An annular fan bypass duct 447 radially
disposed between the fan nacelle 438 and the core
nacelle 432 extends axially aftwardly or downstream
from a flow splitter 434 to the fan nozzle 442.
The fan nozzle 442 includes a circumferential
row of pivotal flaps 473 disposed at an aft end of
the fan nacelle 438 or bypass duct 447. One or more
of the pivotal flaps 473 carry the heat exchanger
heat transfer tubes 6 and, thus, serve as a heat
exchanger 8 . The pivotal flaps 473 also serves as a
variable geometry flow restrictor 2 for opening and
closing a the variable area nozzle 442. The
combination of the heat exchanger heat transfer tubes
6 and the pivotal flaps 473 serve as the integrated
variable geometry flow restrictor and heat exchanger
system 1 for the engine 10 illustrated in FIG. 16.
The integrated variable geometry flow restrictor 2
which is the variable area nozzle 442 are illustrated
in an open position in solid line and closed position
in phantom line in FIG. 16 respectively.
Illustrated in FIG. 17 is an exemplary rear
variable area mixing device or variable area bypass
injector (VABI) 550 which is designed for use in a
variable cycle engine such as engine 10 illustrated
in FIG. 6 . The (VABI) 550 illustrated herein is
designed to selectively open and close and/or
selectively flow an injection portion 553 of fan
bypass flow 48 from a bypass duct 40 into an exhaust
flow path 555 radially surrounded by an inner casing
36. The (VABI) 550 illustrated herein is designed to
be disposed axially between the low pressure turbine
(LPT) 26 and the augmentor 28 or the variable area
exhaust nozzle 29 in an engine similar to the engine
10 illustrated in FIG. 6 . The bypass duct 40 is
defined between outer and inner casings 34, 36.
The (VABI) 550 illustrated herein is yet another
exemplary integrated variable geometry flow
restrictor and heat exchanger system 1 which includes
a slider valve 560 operable to selectively cover one
or more openings 562 in the inner casing 36. The
slider valve 560 and the openings 562 are
circumferentially disposed about a longitudinal
centerline 11 about which the fan bypass duct 40 is
circumscribed. The integrated variable geometry flow
restrictor and heat exchanger system 1 further
includes one or more heat transfer tubes 6 disposed
in each of the openings 562. The slider valve 560
further includes impingement holes 570 (or
alternatively slots) aimed to direct the injection
portion 553 of the fan bypass flow 48 to impinge
directly onto the heat transfer tubes 6 when the
slider valve 560 is closed. The slider valve 560 is
illustrated herein as being an axially translatable
annular sleeve 572 with the impingement holes 570
disposed therethrough and radially located just
outside of the inner casing 36 but, alternatively,
may be rotatable.
While there have been described herein what are
considered to be preferred and exemplary embodiments
of the present invention, other modifications of the
invention shall be apparent to those skilled in the
art from the teachings herein and, it is therefore,
desired to be secured in the appended claims all such
modifications as fall within the true spirit and
scope of the invention. Accordingly, what is desired
to be secured by Letters Patent of the United States
is the invention as defined and differentiated in the
following claims.
CLAIMS
What is claimed:
1 . An integrated variable geometry flow restrictor
and heat exchanger system <1) comprising:
one or more heat exchangers (8) mounted in a
duct 3 ) ,
heat transfer cooling passages (9) in each of
the heat exchangers (8) , and
a variable geometry flow restrictor (2) integral
with each of the heat exchangers (8).
2 . A system (1) as claimed in Claim 1 further
comprising:
a variable area (4) between the heat exchangers
(8) and one of inner and outer casings {36, 34)
bounding the duct (3 ), and
an annular slide valve (102) axially
translatable within the duct (3) and with respect to
the heat exchanger (8) and operable to open and close
or vary the variable area (4) .
3 . A system (1) as claimed in Claim 2 further
comprising the heat exchangers (8) mounted to one of
the inner and outer casings (36, 34) .
4 . A system (1) as claimed in Claim 3 further
comprising the duct (3) being annular and
circumscribed about a longitudinal centerline (11)
and the heat exchangers (8 being circumferentially
distributed around the duct (3) .
5 . A system (1) as claimed in Claim 4 further
comprising circumferentially curved heat transfer
tubes (6) or vanes in the heat exchangers (8).
6 . A system (1) as claimed in Claim 4 further
comprising radial heat transfer tubes (6) or vanes
the heat exchangers (8) .
7 . A system (1) as claimed in Claim 1 further
comprising:
the heat exchangers (8) including an annular
upstream row of tube and fin heat exchangers (170)
rotatable and/or axially translatable with respect to
an annular downstream row of tube and fin heat
exchangers (172),
the annular upstream and downstream rows of tube
and fin heat exchangers (170, 172) including radially
extending upstream and downstream heat transfer tubes
(174, 176) respectively, and
the annular upstream and downstream rows of tube
and fin heat exchangers (170, 172) operable as the
variable geometry flow restrictor (2) for opening and
closing a variable area (4) between the upstream and
downstream heat transfer tubes (174, 176).
8 . A system (1) as claimed in Claim 7 further
comprising the duct (3) being annular and
circumscribed about a longitudinal centerline (11)
and the annular upstream and downstream rows of tube
and fin heat exchangers (170, 172) being annular
segments disposed about the longitudinal centerline
(11).
9 . A system (1) as claimed in Claim 1 further
comprising the heat exchangers (8) including an
annular array (180) of hollow vanes (182) and the
variable geometry flow restrictor (2) including
variable leading edge tips (184) for opening and
closing a variable area (4) between the hollow vanes
(182) .
10. A gas turbine engine (10) comprising:
a longitudinal centerline (11) about which the
engine (10) is circumscribed;
an annular inlet (12) followed in axial
downstream flow relationship by a fan assembly (16),
a high pressure compressor (20), a combustor (22), a
high pressure turbine (24), and a low pressure
turbine (26);
an outer casing (34) radially spaced apart from
an inner casing (36) defining a bypass duct (40)
therebetween;
the bypass duct (40) located around and radially
outwardly of the high pressure compressor (20), the
combustor (22), the high pressure turbine (24), and
the low pressure turbine (26) ;
an integrated variable geometry flow restrictor
and heat exchanger system (1) including one or more
heat exchangers (8) mounted in the duct (40) and a
variable geometry flow restrictor (2) integral with
the heat exchangers (8); and
heat transfer cooling passages (9) in each of
the heat exchangers (8) .
11. A gas turbine engine (10) as claimed in Claim 10
further comprising a variable area (4) between the
heat exchanger 8 ) and one of inner and outer casings
(36,34) bounding the bypass duct (40) and an annular
slide valve (102) axially translatable within the
bypass duct (40) and with respect to the heat
exchanger (8) and operable to open and close or vary
the variable area (4).
12. A gas turbine engine (10) as claimed in Claim 11
further comprising the heat exchangers (8) mounted to
one of the inner and outer casings (36, 34) .
13. A gas turbine engine (10) as claimed in Claim 12
further comprising the heat exchangers (8)
circumferentially distributed around the duct (3) and
circumferentially curved heat transfer tubes (6) or
circumferentially curved vanes in the heat exchangers
(8) or radial heat transfer tubes (6) or radial vanes
in the heat exchangers (8) .
14. A gas turbine engine (10) as claimed in Claim 10
further comprising:
the variable geometry flow restrictor (2)
including at least one slide valve assembly (100)
disposed in the bypass duct (40), and
the heat exchangers (8) including the heat
transfer cooling passages (9) carried by one or more
components (102, 128, 130) of the slide valve
assembly (100).
15. A gas turbine engine (10) as claimed in Claim 14
further comprising:
the components of the slide valve assembly (100)
including at least one of inner and outer fairings
(128, 130) and an axially translatable annular slide
valve (102) within the bypass duct (40),
the variable geometry flow restrictor (2)
including the one of the inner and outer fairings
(128, 130) and the slide valve (102),
the variable area (4) bounded by the one of the
inner and outer fairings (128, 130), and
the slide valve (102) being operable to open and
close or vary the variable area (4) .
16. A gas turbine engine (10) as claimed in Claim 15
further comprising:
the variable area (4) including an inner bypass
cross-sectional area (150) between the slide valve
(102) and the inner fairing (128), and
an outer bypass cross-sectional area (160)
between the slide valve (102) and the outer fairing
(130) .
17. A gas turbine engine (10) as claimed in Claim 10
further comprising a variable area (4) between the
heat exchanger (8) and one of inner and outer casings
(36, 34) bounding the bypass duct (40) and an annular
slide valve (102) axially translatable within the
bypass duct (40) and with respect to the heat
exchanger (8) and operable to open and close or vary
the variable area (4) .
18. A gas turbine engine (410) as claimed in Claim
10 further comprising:
a fan (429) including a longitudinally aft-most
row of generally radially outwardly extending fan
blades (430) in the fan assembly (16),
the bypass duct (447) extending axially
aftwardly and downstream from the fan (429) to a fan
nozzle (442) at a longitudinally aft end (439) of the
fan bypass duct (447),
an annular row of hollow variable-pitch fan
outlet guide vanes (452) radially disposed across the
fan bypass duct (447) longitudinally aft of the fan
(429) ,
the heat transfer cooling passages (9) including
the hollow variable -pitch fan outlet guide vanes
(452) operable for passing cooling air therethrough,
and
the variable geometry flow restrictor (2)
including the hollow variable-pitch fan outlet guide
vanes (452) being pivotable about pivot axes (453)
normal to the engine centerline (412) .
19. A gas turbine engine (410) as claimed in Claim
18 further comprising vane leading or trailing edges
(455, 457) of the variable-pitch fan outlet guide
vanes (452) being pivotable.
20. A gas turbine engine (410) as claimed in Claim
10 further comprising:
a fan (429) including a longitudinally aft-most
row of generally radially outwardly extending fan
blades (430) in the fan assembly (16),
the bypass duct (447) extending axially
aftwardly and downstream from the fan (429) to a fan
nozzle (442) at a longitudinally aft end (439) of the
fan bypass duct (447),
the variable geometry flow restrictor (2)
including a circumferential row of pivotal flaps
(473) disposed in the fan nozzle (442), and
the heat transfer cooling passages (9) carried
by the circumferential row of pivotal flaps (473) .
21. A gas turbine engine (410) as claimed in Claim
20 further comprising the heat transfer cooling
passages (9) including heat exchanger heat transfer
tubes (6) .
22. A gas turbine engine (10) as claimed in Claim 10
further comprising:
a variable area exhaust nozzle (29) axially aft
and downstream of the low pressure turbine (26),
an exhaust flow path (555) radially surrounded
by the inner casing (36) and extending downstream
from the low pressure turbine (26),
a variable area bypass injector (550) generally
radially located between the bypass duct (40) and the
exhaust flow path (555) and axially located aft and
downstream of the low pressure turbine (26) ,
variable geometry flow restrictor (2) of the
variable area bypass injector (550) includes a slider
valve (560) operable to selectively cover one or more
openings (562) in the inner casing 36 between the
bypass duct (40) and the exhaust flow path (555), and
the heat transfer cooling passages (9) include
one or more heat transfer tubes (6) disposed in each
of the openings (562) .
23. A gas turbine engine (10) as claimed in Claim 22
further comprising impingement holes (570) or slots
in the slider valve (560) aimed to direct an
injection portion (553) of fan bypass flow (48) in
the bypass duct (40) to impinge directly onto the
heat transfer tubes (6) when the slider valve (560)
is in a closed position.
24. A gas turbine engine (10) comprising:
a longitudinal centerline (11) about which the
engine (10) is circumscribed;
an annular inlet (12) followed in axial
downstream flow relationship by a fan assembly (16) ,
a high pressure compressor (20), a combustor (22), a
high pressure turbine (24), and a low pressure
turbine (26);
a core engine (414) including the high pressure
compressor (20), the combustor (22), the high
pressure turbine (24), and the low pressure turbine
(26);
a core engine duct (466) of the core engine
(414);
a circumferential row of hollow variable-pitch
vanes (462) extending radially across the core engine
duct (466); and
the hollow variable-pitch vanes (462) being
operable for passing cooling fluid therethrough.
25. A gas turbine engine (10) as claimed in Claim 24
further comprising the circumferential row of hollow
variable-pitch vanes (462) being located in the high
pressure compressor (20) of the engine (10) ,
26. A gas turbine engine (10) as claimed in Claim 24
further comprising the circumferential row of hollow
variable-pitch vanes (462) being located in the low
pressure compressor (428) of the engine (10) .