| United States Patent Application |
20060096272
|
| Kind Code
|
A1
|
|
Baughman; John Lewis
;   et al.
|
May 11, 2006
|
Thrust vectoring aft FLADE engine
Abstract
An aft FLADE gas turbine engine including a fan section drivenly
connected to a low pressure turbine section followed by an aft FLADE
turbine having at least one row of aft FLADE fan blades radially
extending across a FLADE duct circumscribing the aft FLADE turbine, and
at least one thrust vectoring nozzle in pressurized fluid flow receiving
communication with the FLADE duct. One embodiment of the engine includes
spaced apart right and left hand FLADE exhaust nozzles in pressurized
fluid flow receiving communication with the FLADE duct and offset from a
main engine exhaust nozzle located downstream of the aft FLADE turbine.
Right and left hand valves disposed in right and left hand ducts
extending between a FLADE airflow manifold in pressurized fluid flow
receiving communication with the FLADE duct may be used to vector thrust.
The right and left hand FLADE exhaust nozzle may be fixed or thrust
vectoring nozzles.
| Inventors: |
Baughman; John Lewis; (Cincinnati, OH)
; Johnson; James Edward; (Hamilton, OH)
|
| Correspondence Address:
|
Steven J. Rosen;Patent Attorney
4729 Cornell Rd.
Cincinnati
OH
45241
US
|
| Family ID:
|
35695780
|
| Appl. No.:
|
10/982477
|
| Filed:
|
November 5, 2004 |
| Current U.S. Class: |
60/232 ; 60/262 |
| Current CPC Class: |
F02K 3/062 20130101; F02C 3/13 20130101; F01D 5/022 20130101; F02K 3/077 20130101; F02K 3/075 20130101 |
| Class at Publication: |
060/232 ; 060/262 |
| International Class: |
F02K 3/062 20060101 F02K003/062 |
Claims
1. An aft FLADE gas turbine engine comprising: a fan section drivenly
connected to a low pressure turbine section, a core engine located
between the fan section and the low pressure turbine section, an aft
FLADE turbine downstream of the low pressure turbine section, at least
one row of aft FLADE fan blades disposed radially outwardly of and
connected to the aft FLADE turbine, the row of aft FLADE fan blades
radially extending across a FLADE duct circumscribing the aft FLADE
turbine, and at least one thrust vectoring nozzle in pressurized fluid
flow receiving communication with the FLADE duct.
2. An aft FLADE gas turbine engine as claimed in claim 1 further
comprising: the one thrust vectoring nozzle being a right hand FLADE
exhaust nozzle, a left hand FLADE exhaust nozzle in pressurized fluid
flow receiving communication with the FLADE duct, and the right and left
hand FLADE exhaust nozzle are offset from a main engine exhaust nozzle
located downstream of the aft FLADE turbine.
3. An aft FLADE gas turbine engine as claimed in claim 2 wherein the
right and left hand FLADE exhaust nozzle are fixed nozzles.
4. An aft FLADE gas turbine engine as claimed in claim 2 wherein the
right and left hand FLADE exhaust nozzle are thrust vectoring nozzles.
5. An aft FLADE gas turbine engine as claimed in claim 2 further
comprising: a FLADE airflow manifold in pressurized fluid flow receiving
communication with the FLADE duct, the right and left hand FLADE exhaust
nozzles connected in pressurized fluid flow receiving communication with
the FLADE airflow manifold by FLADE air exhaust right and left hand ducts
respectively, right and left hand valves respectively disposed in the
right and left hand ducts, and the right and left hand valves being
operable to control amounts of FLADE exhaust airflow flowed from the
FLADE duct to each of the right and left hand FLADE exhaust nozzles
respectively.
6. An aft FLADE gas turbine engine as claimed in claim 5 wherein the
right and left hand FLADE exhaust nozzle are fixed nozzles.
7. An aft FLADE gas turbine engine as claimed in claim 5 wherein the
right and left hand FLADE exhaust nozzle are thrust vectoring nozzles.
8. An aft FLADE gas turbine engine as claimed in claim 5 further
comprising: a fan bypass duct circumscribing the core engine and in
fluid communication with the fan section, a mixer in fluid communication
with the fan bypass duct and being operably disposed to mix bypass air
from the fan bypass duct with core discharge air exiting the low pressure
turbine section, and the aft FLADE turbine being downstream of the
mixer.
9. An engine as claimed in claim 8 further comprising: a fan inlet to
the fan section, an annular FLADE inlet to the FLADE duct, and the
FLADE inlet is axially located substantially aftwardly of the fan
section.
10. An engine as claimed in claim 9 wherein the FLADE inlet is axially
located aftwardly of the core engine.
11. An engine as claimed in claim 8 further comprising the aft FLADE
turbine connected to and rotatable with a low pressure turbine of the low
pressure turbine section.
12. An engine as claimed in claim 11 further comprising: a fan inlet to
the fan section, an annular FLADE inlet to the FLADE duct, and the
FLADE inlet is axially located substantially aftwardly of the fan
section.
13. An engine as claimed in claim 12 wherein the FLADE inlet is axially
located aftwardly of the core engine.
14. An engine as claimed in claim 8 wherein the aft FLADE turbine is a
free turbine.
15. An engine as claimed in claim 14 further comprising: a fan inlet to
the fan section, an annular FLADE inlet to the FLADE duct, and the
FLADE inlet is axially located substantially axially aftwardly of the fan
section.
16. An engine as claimed in claim 15 wherein the FLADE inlet is located
axially aftwardly of the core engine.
17. An engine as claimed in claim 14 further comprising a variable area
turbine nozzle with variable turbine nozzle vanes located between the
mixer and the aft FLADE turbine.
18. An engine as claimed in claim 17 further comprising: a fan inlet to
the fan section, an annular FLADE inlet to the FLADE duct, and the
FLADE inlet is axially located substantially axially aftwardly of the fan
section.
19. An engine as claimed in claim 18 wherein the FLADE inlet is located
axially aftwardly of the core engine.
20. An engine as claimed in claim 14 further comprising a row of variable
first FLADE vanes radially extending across the FLADE duct axially
forwardly of the row of aft FLADE fan blades.
21. An engine as claimed in claim 20 further comprising: a fan inlet to
the fan section, an annular FLADE inlet to the FLADE duct, and the
FLADE inlet is axially located substantially axially aftwardly of the fan
section.
22. An engine as claimed in claim 21 wherein the FLADE inlet is located
axially aftwardly of the core engine.
23. An engine as claimed in claim 20 further comprising a variable area
turbine nozzle with variable turbine nozzle vanes located between the
mixer and the aft FLADE turbine.
24. An engine as claimed in claim 23 further comprising: a fan inlet to
the fan section, an annular FLADE inlet to the FLADE duct, and the
FLADE inlet is axially located substantially axially aftwardly of the fan
section.
25. An engine as claimed in claim 24 wherein the FLADE inlet is located
axially aftwardly of the core engine.
26. An aircraft comprising: an aft FLADE gas turbine engine within a
fuselage of the aircraft, the gas turbine engine comprising; a fan
section drivenly connected to a low pressure turbine section, a core
engine located between the fan section and the low pressure turbine
section, an aft FLADE turbine downstream of the low pressure turbine
section, at least one row of aft FLADE fan blades disposed radially
outwardly of and connected to the aft FLADE turbine, the row of aft
FLADE fan blades radially extending across a FLADE duct circumscribing
the aft FLADE turbine, and at least one thrust vectoring nozzle in
pressurized fluid flow receiving communication with the FLADE duct.
27. An aircraft as claimed in claim 26 further comprising: the one
thrust vectoring nozzle being a right hand FLADE exhaust nozzle, a left
hand FLADE exhaust nozzle in pressurized fluid flow receiving
communication with the FLADE duct, and the right and left hand FLADE
exhaust nozzle are offset from a main engine exhaust nozzle located
downstream of the aft FLADE turbine.
28. An aircraft as claimed in claim 27 wherein the right and left hand
FLADE exhaust nozzle are fixed nozzles.
29. An aircraft as claimed in claim 27 further comprising: FLADE air
intakes and an engine air intake mounted flush with respect to the
fuselage, the FLADE air intakes axially offset from the engine air
intake, the engine air intake connected to and in fluid communication
with the fan inlet by an engine fixed inlet duct, and the FLADE air
intakes connected to and in fluid communication with the FLADE inlets by
FLADE fixed inlet ducts.
30. An aircraft as claimed in claim 29 further comprising: inlet duct
passages of the engine and FLADE fixed inlet ducts respectively being
two-dimensional and terminating in transition sections between the inlet
duct passages and the fan and FLADE inlets respectively.
31. An aircraft as claimed in claim 27 further comprising: a FLADE
airflow manifold in pressurized fluid flow receiving communication with
the FLADE duct, the right and left hand FLADE exhaust nozzles connected
in pressurized fluid flow receiving communication with the FLADE airflow
manifold by FLADE air exhaust right and left hand ducts respectively,
right and left hand valves respectively disposed in the right and left
hand ducts, and the right and left hand valves being operable to control
amounts of FLADE exhaust airflow flowed from the FLADE duct to each of
the right and left hand FLADE exhaust nozzles respectively.
32. An aircraft as claimed in claim 31 wherein the right and left hand
FLADE exhaust nozzle are fixed nozzles.
33. An aircraft as claimed in claim 31 wherein the right and left hand
FLADE exhaust nozzle are thrust vectoring nozzles.
34. An aircraft as claimed in claim 31 further comprising: a fan bypass
duct circumscribing the core engine and in fluid communication with the
fan section, a mixer in fluid communication with the fan bypass duct and
being operably disposed to mix bypass air from the fan bypass duct with
core discharge air exiting the low pressure turbine section, and the aft
FLADE turbine being downstream of the mixer.
35. An aircraft as claimed in claim 31 further comprising: a fan inlet
to the fan section, an annular FLADE inlet to the FLADE duct, and the
FLADE inlet is axially located substantially aftwardly of the fan
section.
36. An aircraft as claimed in claim 35 wherein the FLADE inlet is axially
located aftwardly of the core engine.
37. An aircraft as claimed in claim 35 wherein the aft FLADE turbine is a
free turbine.
38. An aircraft as claimed in claim 37 wherein the FLADE inlet is axially
located aftwardly of the core engine.
39. An aircraft as claimed in claim 31 further comprising: FLADE air
intakes and an engine air intake mounted flush with respect to the
fuselage, the FLADE air intakes axially offset from the engine air
intake, the engine air intake connected to and in fluid communication
with the fan inlet by an engine fixed inlet duct, and the FLADE air
intakes connected to and in fluid communication with the FLADE inlets by
FLADE fixed inlet ducts.
40. An aircraft as claimed in claim 39 wherein the right and left hand
FLADE exhaust nozzle are fixed nozzles.
41. An aircraft as claimed in claim 39 wherein the right and left hand
FLADE exhaust nozzle are thrust vectoring nozzles.
42. An aircraft as claimed in claim 39 further comprising: a fan bypass
duct circumscribing the core engine and in fluid communication with the
fan section, a mixer in fluid communication with the fan bypass duct and
being operably disposed to mix bypass air from the fan bypass duct with
core discharge air exiting the low pressure turbine section, and the aft
FLADE turbine being downstream of the mixer.
43. An aircraft as claimed in claim 39 further comprising: a fan inlet
to the fan section, an annular FLADE inlet to the FLADE duct, and the
FLADE inlet is axially located substantially aftwardly of the fan
section.
44. An aircraft as claimed in claim 43 wherein the FLADE inlet is axially
located aftwardly of the core engine.
45. An aircraft as claimed in claim 43 wherein the aft FLADE turbine is a
free turbine.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] This invention relates to thrust vectoring of aircraft gas turbine
engines and, more particularly, to thrust vectoring of FLADE engines.
[0002] High performance variable cycle gas turbine engines are being
designed because of their unique ability to operate efficiently at
various thrust settings and flight speeds both subsonic and supersonic.
An important feature of the variable cycle gas turbine engine which
contributes to its high performance is its capability of maintaining a
substantially constant inlet airflow as its thrust is varied. This
feature leads to important performance advantages under less than full
power engine settings or maximum thrust conditions, such as during
subsonic cruise.
[0003] One particular type of variable cycle engine called a FLADE engine
(FLADE being an acronym for "fan on blade") is characterized by an outer
fan driven by a radially inner fan and discharging its FLADE air into an
outer fan duct which is generally co-annular with and circumscribes an
inner fan duct circumscribing the inner fan. One such engine, disclosed
in U.S. Pat. No. 4,043,121, entitled "Two Spool Variable Cycle Engine",
by Thomas et al., provides a FLADE fan and outer fan duct within which
variable guide vanes control the cycle variability by controlling the
amount of air passing through the FLADE outer fan duct. Other high
performance aircraft variable cycle gas turbine FLADE engines capable of
maintaining an essentially constant inlet airflow over a relatively wide
range of thrust at a given set of subsonic flight ambient conditions such
as altitude and flight Mach No. in order to avoid spillage drag and to do
so over a range of flight conditions have been studied. This capability
is particularly needed for subsonic part power engine operating
conditions. Examples of these are disclosed in U.S. Pat. No. 5,404,713,
entitled "Spillage Drag and Infrared Reducing Flade Engine", U.S. Pat.
No. 5,402,963, entitled "Acoustically Shielded Exhaust System for High
Thrust Jet Engines", U.S. Pat. No. 5,261,227, entitled "Variable Specific
Thrust Turbofan Engine", and European Patent No. EP0,567,277, entitled
"Bypass Injector Valve For Variable Cycle Aircraft Engines". A FLADE
aircraft gas turbine engine with counter-rotatable fans is disclosed in
U.S. patent application Ser. No. (133,746), entitled "FLADE GAS TURBINE
ENGINE WITH COUNTER-ROTATABLE FANS".
[0004] FLADE engines have the fan blade attached to one of the front
fans. This can lead to low pressure spool designs that are compromised
because of the limitations in rotor speeds and increased stresses caused
by the FLADE blade attachment and location. The front fan mounted FLADE
fan blades also are difficult to adapt to present engines or engine
designs. It would be very expensive to adapt an existing engine to test a
front fan mounted FLADE fan. It would be difficult to demonstrate some of
the system benefits offered by a FLADE engine concept at a reasonable
cost relative to that of a new low pressure system or defined around an
existing core engine.
[0005] It is highly desirable to have a FLADE engine that allows a low
pressure spool design that is uncompromised because of limitations in
rotor speeds and increased stresses caused by the FLADE blade attachment
and location. It is highly desirable to have an engine in which FLADE fan
blades are not difficult to adapt to present engines or engine designs
and that would not be very expensive to adapt to an existing engine to
test as compared to a front fan mounted FLADE fan. It is also desirable
to be able to demonstrate some of the system benefits offered by a FLADE
engine concept without a great deal of difficulty and at a reasonable
cost relative to that of a new low pressure system or defined around an
existing core engine.
[0006] Another concern of aircraft and aircraft engine designers and
particularly those designing high speed highly maneuverable military
aircraft are constantly seeking better ways for controlling the aircraft
and increasing its maneuverability in flight. These are needed for
anti-aircraft missile avoidance and other combat maneuvers. Additionally,
aircraft designers are trying to improve short take off and landing
capabilities of aircraft. Exhaust systems, particularly for modern, high
speed, military aircraft, have been adapted to provide a high degree of
maneuverability over a wide variety of flight conditions including
altitude, speed and Mach number while maintaining cruise efficiency.
[0007] Aircraft maneuverability may be provided by aircraft control
surfaces such as wing flaps or ailerons or vertical fins or rudders.
Aircraft control surfaces, however, are somewhat limited in their
effectiveness because of large differences in operational flight
conditions such as air speed. Aircraft control surfaces also increase an
aircraft's radar signature making it more vulnerable to anti-aircraft
fire and missile. Thrust vectoring nozzles, are more effective because
they allow large thrust loads to be quickly applied in the yaw and pitch
directions of the aircraft, thereby, providing the aircraft with enhanced
maneuverability which is relatively independent of air speed. Thrust
vectoring nozzles are complicated, bulky, heavy, and expensive. Other
thrust vectoring methods include use of nozzle internal fluidic injection
and/or mechanical flow diversion devices to skew the thrust.
[0008] The thrust vectoring aft FLADE aircraft gas turbine engine powered
aircraft is highly maneuverable. The thrust vectoring aft FLADE aircraft
gas turbine engine is not complex, heavy, bulky, or expensive, and yet,
is very effective for thrust vectoring.
SUMMARY OF THE INVENTION
[0009] An aft FLADE gas turbine engine includes a fan section drivenly
connected to a low pressure turbine section, a core engine located
between the fan section and the low pressure turbine section, a fan
bypass duct circumscribing the core engine and in fluid communication
with the fan section, a mixer downstream of the low pressure turbine
section and in fluid communication with the fan bypass duct, and an aft
FLADE turbine downstream of the mixer. At least one row of aft FLADE fan
blades is disposed radially outwardly of and drivenly connected to the
aft FLADE turbine. The row of aft FLADE fan blades radially extend across
a FLADE duct circumscribing the aft FLADE turbine. At least one thrust
vectoring nozzle is in pressurized fluid flow receiving communication
with the FLADE duct.
[0010] One embodiment of the engine includes spaced apart right and left
hand FLADE exhaust nozzles in pressurized fluid flow receiving
communication with the FLADE duct and offset from a main engine exhaust
nozzle located downstream of the aft FLADE turbine. Right and left hand
valves may be disposed in right and left hand ducts extending between a
FLADE airflow manifold in pressurized fluid flow receiving communication
with the FLADE duct. The right and left hand valves being operable to
control amounts of FLADE exhaust airflow flowed from the FLADE duct to
each of the right and left hand FLADE exhaust nozzles respectively to
vector thrust. The right and left hand FLADE exhaust nozzle may be fixed
or thrust vectoring nozzles.
[0011] An aircraft may be constructed with the aft FLADE gas turbine
engine within a fuselage of the aircraft. The aircraft may include FLADE
air intakes and an engine air intake mounted flush with respect to the
fuselage. The FLADE air intakes are axially offset from the engine air
intake which is connected to and in fluid communication with a fan inlet
to the fan section by an engine fixed inlet duct. The FLADE air intakes
are connected to and in fluid communication with FLADE inlets to the
FLADE duct by FLADE fixed inlet ducts.
[0012] More particular embodiments of the engine include a row of
variable first FLADE vanes radially extending across the FLADE duct
axially forwardly of the row of aft FLADE fan blades. One embodiment of
the engine further includes a fan inlet to the fan section and an annular
FLADE inlet to the FLADE duct arranged so that the FLADE inlet is axially
located substantially aftwardly of the fan section and, in a more
particular embodiment, the FLADE inlet is axially located aftwardly of
the core engine. The aft FLADE turbine may be connected to and rotatable
with a low pressure turbine of the low pressure turbine section or may be
a free turbine. The engine may incorporate a variable area turbine nozzle
with variable turbine nozzle vanes located aft and downstream of the
mixer and the low pressure turbine.
[0013] A power extraction apparatus may be placed within the engine and
drivenly connected to the aft FLADE turbine. In one embodiment, the power
extraction apparatus may be located in a hollow engine nozzle centerbody
of the engine located aft and downstream of the aft FLADE turbine. One
embodiment of the power extraction apparatus is an electrical generator
drivenly connected through a speed increasing gearbox to the aft FLADE
turbine. Another embodiment of the power extraction apparatus is a power
takeoff assembly including a housing disposed within the engine such as
in the hollow engine nozzle centerbody and having a power takeoff shaft
drivenly connected to the aft FLADE turbine through a right angle
gearbox.
[0014] A variable or fixed throat area engine nozzle may be incorporated
downstream and axially aft of the mixer and the fan bypass duct. Another
more particular embodiment of the engine includes a plurality of
circumferentially disposed hollow struts in fluid flow communication with
the FLADE duct and a substantially hollow centerbody supported by and in
fluid flow communication with the hollow struts. Cooling apertures in the
centerbody and in a wall of the engine nozzle downstream of the variable
throat area are in fluid communication with the FLADE duct.
[0015] A variable area FLADE air nozzle including an axially translatable
plug within the hollow centerbody and a radially outwardly positioned
fixed nozzle cowling of the centerbody may also be used in the engine.
Aft thrust augmenting afterburners may be incorporated aft and downstream
of the aft FLADE turbine. A forward afterburner may be axially disposed
between the mixer and the aft FLADE turbine to provide additional energy
upon demand to the aft FLADE turbine and additional power to the row of
aft FLADE fan blades and the power extraction apparatus such as the
electrical generator or the power takeoff assembly.
[0016] It is, thus, highly desirable to provide an FLADE aircraft gas
turbine engine powered aircraft with a thrust vectoring nozzle that is
not complex, heavy, bulky, nor expensive, and yet, very effective for
thrust vectoring. The aft FLADE gas turbine engine may be used within a
fuselage of the aircraft. FLADE air intakes and an engine air intake may
be mounted flush with respect to the fuselage. The FLADE air intakes are
axially offset from the engine air intake. The engine air intake may be
connected to and in fluid communication with the fan inlet by an engine
fixed inlet duct. The FLADE air intakes may be connected to and in fluid
communication with the FLADE inlets by FLADE fixed inlet ducts. Inlet
duct passages of the engine and the FLADE fixed inlet ducts respectively
may be two-dimensional and terminating in transition sections between the
inlet duct passages and the fan and FLADE inlets respectively.
[0017] The aft FLADE turbine allows a FLADE engine to have a low pressure
spool design that is uncompromised because of limitations in rotor speeds
and increased stresses caused by the FLADE blade attachment and location.
Aft FLADE fan blades mounted on the aft FLADE turbine are not difficult
to adapt to present engines or engine designs. The aft FLADE turbine is
not very expensive to adapt to an existing engine to test as compared to
a front fan mounted FLADE fan.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The foregoing aspects and other features of the invention are
explained in the following description, taken in connection with the
accompanying drawings where:
[0019] FIG. 1 is a schematical cross-sectional view illustration of an
aircraft thrust vectoring aft FLADE gas turbine engine with a short FLADE
duct and dual thrust vectoring nozzles installed in an aircraft.
[0020] FIG. 2 is a schematical cross-sectional view illustration of a
thrust vectoring aft FLADE gas turbine engine with a long duct FLADE duct
and dual thrust vectoring nozzles installed in an aircraft.
[0021] FIG. 3 is a schematical cross-sectional view illustration of the
aft FLADE gas turbine engine with a single direction of rotation fan
section and an aft FLADE blade and turbine illustrated in FIGS. 1 and 2.
[0022] FIG. 4 is a schematical cross-sectional view illustration of an
alternative aft FLADE gas turbine engine with two fan sections and two
bypass inlets.
[0023] FIG. 5 is an alternative schematical cross-sectional view
illustration of the engine in FIG. 3 with exhaust nozzle cooling.
[0024] FIG. 6 is a schematical cross-sectional view illustration of
another exemplary embodiment of an aircraft thrust vectoring aft FLADE
gas turbine engine with an aft FLADE blade and turbine and a short FLADE
duct.
[0025] FIG. 7 is a schematical cross-sectional view illustration of the
aircraft thrust vectoring aft FLADE aircraft gas turbine engine
illustrated in FIG. 3 with a first afterburner upstream of a free aft
FLADE turbine.
[0026] FIG. 8 is a schematical cross-sectional view illustration of the
aft FLADE gas turbine engine illustrated in FIG. 3 with a variable area
turbine nozzle and a thrust augmenting afterburner downstream of an aft
FLADE turbine.
[0027] FIG. 9 is a schematical cross-sectional view illustration of yet
another embodiment of an aircraft thrust vectoring aft FLADE aircraft gas
turbine engine with counter-rotatable fans and an aft FLADE blade and
turbine.
[0028] FIG. 10 is a schematical cross-sectional view illustration of the
aft FLADE gas turbine engine illustrated in FIG. 3 with an aft FLADE
blade and turbine driving connected to a power takeoff shaft.
[0029] FIG. 11 is a schematical cross-sectional view illustration of the
aft FLADE gas turbine engine illustrated in FIG. 3 with an aft FLADE
blade and turbine driving connected to an electrical generator located
within the engine.
[0030] FIG. 12 is a schematical cross-sectional view illustration of the
aft FLADE gas turbine engine illustrated in FIG. 3 with an aft FLADE
blade and turbine driving connected to two electrical generators located
within the engine.
DETAILED DESCRIPTION OF THE INVENTION
[0031] Schematically illustrated in cross-section in FIG. 1 is an
exemplary embodiment of an aircraft 124 having a single offset flush
mounted engine air intake 127 connected to and in fluid communication
with an aircraft thrust vectoring aft FLADE aircraft gas turbine engine
1. An annular fan inlet 11 of the aircraft aft FLADE engine 1 is
connected to the air intake 127 by an engine fixed inlet duct 126. The
fan inlet 11 is axially offset from an annular FLADE inlet 8 to a FLADE
duct 3. Flush mounted dual FLADE air intakes 129 are connected to and in
fluid communication with the annular FLADE inlets 8 by FLADE fixed inlet
ducts 128.
[0032] The FLADE air intakes 129 are axially offset from the engine air
intake 127. This provides great flexibility in designing and constructing
efficient engines, aircraft, and aircraft with engines completely mounted
within the aircraft's fuselage 113 or body and the FLADE air intakes 129
and the engine air intake 127 are mounted flush with respect to the
fuselage 113. Inlet duct passages 111 of the engine fixed inlet duct 126
and the FLADE fixed inlet ducts 128 may be two-dimensional terminating in
transition sections 119 between the inlet duct passages 111 and the
axisymmetric annular fan and FLADE inlets 11 and 8.
[0033] The FLADE duct 3 leads to at least one thrust vectoring nozzle 123
for maneuvering the aircraft. Right and left hand FLADE exhaust nozzles
125 and 135, respectively, illustrated in FIG. 1 serve as thrust
vectoring nozzles 123. The right and left hand FLADE exhaust nozzles 125
and 135 are fixed nozzles and are offset from a main engine exhaust
nozzle 218 which may be a variable or fixed throat area engine nozzle. A
FLADE airflow manifold 231 collects FLADE exhaust airflow 154 from the
FLADE duct 3 and directs it through FLADE air exhaust right and left hand
ducts 155 and 156 to the right and left hand FLADE exhaust nozzles 125
and 135, respectively. More than one pair of FLADE exhaust nozzles may be
used.
[0034] Right and left hand valves 162 and 164, respectively, disposed in
the right and left hand ducts 155 and 156 control the amount of the FLADE
exhaust airflow 154 that goes to each of the right and left hand FLADE
exhaust nozzles 125 and 135, respectively. Thrust vectoring and yaw of
the aircraft is accomplished by flowing unequal amounts of the FLADE
exhaust airflow 154 to the right and left hand FLADE exhaust nozzles 125
and 135. The unequal amounts of the FLADE exhaust airflow 154 to the
right and left hand FLADE exhaust nozzles 125 and 135 produces a turning
moment about a center of gravity CG of the aircraft.
[0035] Equal amounts of the FLADE exhaust airflow 154 flowed through the
right and left hand valves 162 and 164 in the right and left hand ducts
155 and 156 provides unvectored flight of the aircraft. Pitch may be
accomplished by having vectoring versions of the right and left hand
FLADE exhaust nozzles 125 and 135. Thrust vectoring versions of the right
and left hand FLADE exhaust nozzles 125 and 135 may be gimballing
nozzles, two-dimensional pitch inducing nozzles, fluidic nozzles, and
other types of thrust vectoring nozzles which individually vector the
exhaust flow coming out of the right and left hand FLADE exhaust nozzles
125 and 135.
[0036] The engine 1 illustrated in FIGS. 1-3, 7, 8, 10, and 11 are of the
single bypass type having but a single bypass inlet 272 as compared to
the engine 1 illustrated in FIGS. 4-6 and 9 having both the first and
second bypass inlets 42 and 46 to the fan bypass duct 40 and have
counter-rotating first and core fans. Schematically illustrated in
cross-section in FIG. 2 is an alternative exemplary embodiment of the
aircraft 124 in which the FLADE duct 3 is a long duct extending to the
annular fan inlet 11 of the aircraft aft FLADE engine 1. The FLADE duct 3
is also connected to the air intake 127 by the engine fixed inlet duct
126.
[0037] Schematically illustrated in cross-section in FIG. 3 is an
exemplary aircraft aft FLADE engine 1. The engine 1 illustrated in FIG. 3
includes a fan section 115 with a single direction of rotation fan 330
with three fan stages 332 downstream of a fan inlet 11. Downstream and
axially aft of the fan section 115 is a core engine 18 having an annular
core engine inlet 17 and a generally axially extending axis or centerline
12 generally extending forward 14 and aft 16. A single fan bypass duct 40
located downstream and axially aft of the fan section 115 circumscribes
the core engine 18. The single bypass inlet 272 includes an annular
splitter 293 to split fan airflow 50 into bypass airflow 258 and core
airflow 256.
[0038] The core engine 18 includes, in downstream serial axial flow
relationship, a high pressure compressor 20, a combustor 22, and a high
pressure turbine 23 having a row of high pressure turbine blades 24. A
high pressure shaft 26, disposed coaxially about the centerline 12 of the
engine 1, fixedly interconnects the high pressure compressor 20 and the
high pressure turbine blades 24. The combination or assembly of the high
pressure compressor 20 drivenly connected to the high pressure turbine 23
by the high pressure shaft 26 is designated a high pressure spool 47.
[0039] The core engine 18 is effective for generating combustion gases.
Pressurized air from the high pressure compressor 20 is mixed with fuel
in the combustor 22 and ignited, thereby, generating combustion gases.
Some work is extracted from these gases by the high pressure turbine
blades 24 which drives the high pressure compressor 20. The combustion
gases are discharged from the core engine 18 into single direction of
rotation low pressure turbine 319. The low pressure turbine 319 is
drivingly connected to the single direction of rotation fan 330 by a low
pressure shaft 321, the combination or assembly being designated a low
pressure spool 290.
[0040] A mixer 49, illustrated as a lobed or chute mixer, is disposed
downstream of and at an aft end of the fan bypass duct 40 and downstream
of and aft of low pressure turbine blades 328 of the low pressure turbine
319. The mixer 49 is used to mix bypass air 78 with core discharge air 70
exiting the low pressure turbine 319 to form a mixed flow 188. One
alternative version of the mixer 49 is an aft variable area bypass
injector (VABI) door disposed at an aft end of the fan bypass duct 40 to
mix bypass air 78 with core discharge air 70.
[0041] Exhaust gases from the mixer 49 are directed through an aft FLADE
turbine 160 having a plurality of aft FLADE turbine blades 254 and
located downstream and aft of the mixer 49. The FLADE duct 3
circumscribes an aft FLADE turbine 160. An aft FLADE fan 2 includes at
least one row of aft FLADE fan blades 5 which extend radially outwardly
from and are drivenly connected to the aft FLADE turbine 160 across the
FLADE duct 3 circumscribing the aft FLADE turbine 160. A FLADE airflow 80
is powered by the aft FLADE fan blades 5 and put to use downstream of the
aft FLADE fan blades 5. The aft FLADE fan blades 5 extend radially
outwardly from an annular rotatable FLADE turbine shroud 250 attached to
and circumscribing the aft FLADE turbine blades 254 of the aft FLADE
turbine 160. The FLADE turbine shroud 250 separates the aft FLADE fan
blades 5 from the aft FLADE turbine blades 254.
[0042] Schematically illustrated, in cross-section in FIG. 4, is an
alternative exemplary aircraft aft FLADE engine 1. The engine 1 in FIG. 4
includes a fan section 115 with a fan 330 downstream of variable inlet
guide vanes 4 at an inlet 11 and a long duct FLADE duct 3. Fairings 190
disposed across the FLADE duct 3 surround variable vane shafts 194
passing through the FLADE duct 3 that are used to vary and control the
pitch of the variable inlet guide vanes 4. Downstream of the fan section
115 is a core engine 18 including, in downstream serial axial flow
relationship, a core driven fan 37 having a row of core driven fan blades
36, a high pressure compressor 20, a combustor 22, and a high pressure
turbine 23 having a row of high pressure turbine blades 24. A high
pressure shaft 26, disposed coaxially about the centerline 12 of the
engine 1, fixedly interconnects the high pressure compressor 20 and the
high pressure turbine blades 24. The combination or assembly of the core
driven fan 37 and the high pressure compressor 20 drivenly connected to
the high pressure turbine 23 by the high pressure shaft 26 is designated
a high pressure spool 47.
[0043] A first bypass inlet 42 to the fan bypass duct 40 is disposed
axially between the fan section 115 and the core driven fan 37. The fan
blades 333 of the fan 330 radially extend across a first fan duct 138. A
row of circumferentially spaced-apart fan stator vanes 35 radially extend
across the first fan duct 138, downstream of the fan blades 333, and
axially between the fan blades 333 and the first bypass inlet 42 to the
fan bypass duct 40. The row of the core driven fan blades 36 of the core
driven fan 37 radially extend across an annular second fan duct 142. The
second fan duct 142 begins axially aft of the first bypass inlet 42 and
is disposed radially inwardly of the fan bypass duct 40. An annular first
flow splitter 45 is radially disposed between the first bypass inlet 42
and the second fan duct 142.
[0044] The full engine airflow 15 is split between the FLADE inlet 8 and
the fan inlet 11. A fan airflow 50 passes through the fan inlet 11 and
then the fan section 115. A first bypass air portion 52 of the fan
airflow 50 passes through the first bypass inlet 42 of the fan bypass
duct 40 when a front variable area bypass injector (VABI) door 44 in the
first bypass inlet 42 is open and with the remaining air portion 54
passing through the core driven fan 37 and its row of core driven fan
blades 36.
[0045] A row of circumferentially spaced-apart core driven fan stator
vanes 34 within the second fan duct 142 are disposed axially between the
row of second fan blades 32 and the core driven fan blades 36 of the core
driven fan 37. The row of the core driven fan stator vanes 34 and the
core driven fan blades 36 of the core driven fan 37 are radially disposed
across the second fan duct 142. A vane shroud 106 divides the core driven
fan stator vanes 34 into radially inner and outer vane hub and tip
sections 85 and 84, respectively. The fan shroud 108 divides the core
driven fan blades 36 into the radially inner and outer blade hub and tip
sections 39 and 38, respectively.
[0046] A second bypass airflow portion 56 is directed through a fan tip
duct 146 across the vane tip sections 84 of the core driven fan stator
vanes 34 and across the blade tip sections 38 of the core driven fan
blades 36 into a second bypass inlet 46 of a second bypass duct 58 to the
fan bypass duct 40. An optional middle variable area bypass injector
(VABI) door 83 may be disposed at an aft end of the second bypass duct 58
for modulating flow through the second bypass inlet 46 to the fan bypass
duct 40.
[0047] The fan tip duct 146 includes the vane and fan shrouds 106 and 108
and a second flow splitter 55 at a forward end of the vane shroud 106.
First and second varying means 91 and 92 are provided for independently
varying flow areas of the vane hub and tip sections 85 and 84,
respectively. Exemplary first and second varying means 91 and 92 include
independently variable vane hub and tip sections 85 and 84, respectively
(see U.S. Pat. No. 5,806,303). The independently variable vane hub and
tip sections 85 and 84 designs may include having the entire vane hub and
tip sections 85 and 84 be independently pivotable. Other possible designs
are disclosed in U.S. Pat. Nos. 5,809,772 and 5,988,890.
[0048] Another embodiment of the independently variable vane hub and tip
sections 85 and 84 includes pivotable trailing-edge hub and tip flaps 86
and 88 of the independently variable vane hub and tip sections 85 and 84.
The first and second varying means 91 and 92 can include independently
pivoting flaps. Alternative varying means for non-pivotable, fan stator
vane designs include axially moving unison rings and those means known
for mechanical clearance control in jet engines (i.e., mechanically
moving circumferentially surrounding shroud segments radially towards and
away from a row of rotor blade tips to maintain a constant clearance
despite different rates of thermal expansion and contraction). Additional
such varying means for non-pivotable, fan stator vane designs include
those known for extending and retracting wing flaps on airplanes and the
like.
[0049] Exemplary first and second varying means 91 and 92, illustrated in
FIG. 4, include an inner shaft 94 coaxially disposed within an outer
shaft 96. The inner shaft 94 is rotated by a first lever arm 98 actuated
by a first unison ring 100. The outer shaft 96 is rotated by a second
lever arm 102 actuated by a second unison ring 104. The inner shaft 94 is
attached to the pivotable trailing edge hub flap 86 of the vane hub
section 85 of the fan stator vane 34. The outer shaft 96 is attached to
the pivotable trailing edge tip flap 88 of the vane tip section 84 of the
fan stator vane 34. It is noted that the lever arms 98 and 102 and the
unison rings 100 and 104 are all disposed radially outward of the fan
stator vanes 34. Other such pivoting means include those known for
pivoting variable stator vanes of high pressure compressors in jet
engines and the like.
[0050] Referring to FIG. 4 by way of example, a variable throat area main
engine exhaust nozzle 218, having a variable throat area A8, is
downstream and axially aft of the aft FLADE turbine 160 and the fan
bypass duct 40. The main engine exhaust nozzle 218 includes an axially
translatable radially outer annular convergent and divergent wall 220
spaced radially outwardly apart from a radially fixed and axially
translatable annular inner wall 222 on the centerbody 72. The
translatable radially outer annular convergent and divergent wall 220
controls a throat area A8 between the outer annular convergent and
divergent wall 220 and the radially fixed and axially translatable
annular inner wall 222. The translatable radially outer annular
convergent and divergent wall 220 also controls a nozzle exit area A9 of
the main engine exhaust nozzle 218. Alternatively, a variable throat area
convergent/divergent nozzle with flaps may be used as disclosed in U.S.
Pat. No. 5,404,713. Illustrated in FIGS. 3, 10, and 11 is a fixed throat
area engine nozzle 216 axially aft of the mixer 49 and the fan bypass
duct 40.
[0051] The plurality of circumferentially disposed hollow struts 208 are
in fluid communication with and operable to receive air from the FLADE
duct 3. The hollow struts 208 structurally support and flow air to the
centerbody 72 which is substantially hollow. A variable area FLADE air
nozzle 213 includes an axially translatable plug 172 which cooperates
with a radially outwardly positioned fixed nozzle cowling 174 of the
centerbody 72 to exhaust FLADE airflow 80 received from the hollow struts
208 and return work to the engine in the form of thrust.
[0052] An optional variable area turbine nozzle 180 with variable turbine
nozzle vanes 182 is illustrated in FIG. 4 located between the mixer 49
and the aft FLADE turbine 160. Variable area nozzle vane shafts 192, that
are used to vary and control the pitch of the variable turbine nozzle
vanes 182, pass through the variable vane shafts 194 that are used to
vary and control the pitch of the variable first FLADE vanes 6. A row of
second FLADE vanes 7 is illustrated in FIG. 1 as being fixed but may be
variable. The row of second FLADE vanes 7 is also located within the
FLADE duct 3 but axially aftwardly and downstream of the row of FLADE fan
blades 5. The second FLADE vanes 7 are used to deswirl the FLADE airflow
80.
[0053] FIGS. 5-8 illustrate a nozzle cooling arrangement in which at
least some of the FLADE airflow 80 is used as cooling air 251 which
flowed through the hollow struts 208 into the substantially hollow
centerbody 72. The cooling air 251 is then flowed through cooling
apertures 249 in the centerbody 72 downstream of the variable throat area
A8 to cool an outer surface of the centerbody. Some of the FLADE airflow
80 may also be used as cooling air 251 for cooling the radially annular
outer wall 220 of the main engine exhaust nozzle 218 downstream of the
variable throat area A8 in the same manner. Cooling of the annular outer
wall 220 and the hollow centerbody 72 is helpful when thrust augmenting
forward and aft afterburners 226 and 224, illustrated in FIGS. 7 and 8
respectively, are ignited. The thrust augmenting forward afterburner 226
is forward and upstream of the aft FLADE turbine 160 and the aft
afterburner 224 is aft and downstream of the aft FLADE turbine 160. The
apertures may be angled to provide film cooling along the centerbody 72
and/or the hollow struts 208. Holes, shaped and angled holes, and slots
and angled slots are among the types of cooling apertures 249 that may be
used.
[0054] Referring to FIG. 8, the augmenter includes an exhaust casing 233
and liner 234 within which is defined a combustion zone 236. The thrust
augmenting afterburner 224 is mounted between the turbines and the
exhaust nozzle for injecting additional fuel when desired during reheat
operation for burning in the augmenter for producing additional thrust.
In a bypass turbofan engine, an annular bypass duct extends from the fan
to the augmenter for bypassing a portion of the fan air around the core
engine to the augmenter. The bypass air is used in part for cooling the
exhaust liner and also is mixed with the core gases prior to discharge
through the exhaust nozzle.
[0055] Various types of flameholders are known and typically include
radial and circumferential V-shaped gutters which provide local low
velocity recirculation and stagnation regions therebehind, in otherwise
high velocity core gas flow, for sustaining combustion during reheat
operation. Since the core gases are the product of combustion in the core
engine, they are initially hot when they leave the turbine, and are
further heated when burned with the bypass air and additional fuel during
reheat operation.
[0056] The embodiments of the engine 1 illustrated in FIGS. 3 and 6 have
the fan inlet 11 to the fan section 115 axially offset from the annular
FLADE inlet 8 to the FLADE duct 3. The exemplary axially offset FLADE
inlet 8 is illustrated as being axially located substantially aftwardly
of the fan section 115 and, more particularly, it is axially located
aftwardly of the core engine 18.
[0057] Further illustrated in FIG. 3 is a variation of the embodiment of
the aft FLADE engine 1 incorporating a "bolt on" aft FLADE module 260
which incorporates a free aft FLADE turbine 160 and can be added to an
existing engine 262 for various purposes including, but not limited to,
testing and design verification. Another feature illustrated in FIG. 3 is
a FLADE power extraction apparatus 264, illustrated as an electrical
generator 266 disposed within the engine 1 and drivenly connected through
a speed increasing gearbox 268 to the aft FLADE turbine 160. The
electrical generator 266 is illustrated as being located within the
hollow engine nozzle centerbody 72 but may be placed elsewhere in the
engine 1 as illustrated in FIG. 12.
[0058] Another embodiment of the power extraction apparatus 264 is a
power takeoff assembly 270, as illustrated in FIG. 10, including a
housing 274 disposed within the hollow engine nozzle centerbody 72. A
power takeoff shaft 276 is drivenly connected to the aft FLADE turbine
160 through a right angle gearbox 278 within the housing 274. A power
takeoff shaft is typically used to drive accessory machinery mounted
external to the engine such as gearboxes, generators, oil and fuel pumps.
The FLADE power extraction apparatus 264 allows more flexibility in the
design of the engine 1 so that the power used by the aft FLADE fan blades
5 is a small percentage of the power extracted by the aft FLADE turbine
160 from the mixed flow 188 and, therefore, varying and controlling the
amount of the FLADE airflow 80 will have a small effect on the efficiency
of the aft FLADE turbine 160.
[0059] Illustrated in FIG. 11 is an engine 1 with the FLADE inlet 8 and
the fan inlet 11 axially located together and not axially offset from
each other as the embodiments illustrated in FIGS. 3 and 6. The engine 1
includes a long duct FLADE duct 3. The electrical generator 266 is
disposed within the hollow engine nozzle centerbody 72 and drivingly
connected through the speed increasing gearbox 268 to the aft FLADE
turbine 160. The fan 330 is downstream of variable inlet guide vanes 4 at
the inlet 11. Fairings 190 disposed across the FLADE duct 3 surround
variable vane shafts 194 passing through the FLADE duct 3 that are used
to vary and control the pitch of the variable inlet guide vanes 4.
[0060] Illustrated in FIG. 12 is a portion of an engine 1 with more than
one FLADE power extraction apparatus 264 disposed within the engine 1.
Forward and aft electrical generators 366 and 367 are disposed within the
engine 1 forward and aft or downstream and upstream of the aft FLADE
turbine 160. The forward and aft electrical generators 366 and 367 are
drivenly connected through forward and aft speed increasing gearboxes 368
and 369 to the aft FLADE turbine 160. Also illustrated in FIGS. 10-12 is
a fixed throat area main engine exhaust nozzle 216 having a fixed throat
area A8 downstream and axially aft of the aft FLADE turbine 160. Power
extraction may be accomplished in such a fixed throat area engine with
the variable first FLADE vanes 6 scheduled closed.
[0061] Illustrated in FIG. 7 is an engine 1 with a forward afterburner
226 axially disposed in the mixed flow 188 between the mixer 49 and the
aft FLADE turbine 160. The forward afterburner 226 includes forward fuel
spraybars 230 and forward flameholders 232. The forward afterburner 226
may be used to add additional energy to the mixed flow 188 upstream of
the aft FLADE turbine 160 if more power is required for the aft FLADE
turbine 160 to provide additional energy upon demand to the aft FLADE
turbine 160 for the aft FLADE fan blades 5 and/or the power extraction
apparatus 264 such as the electrical generator 266 or the power takeoff
assembly 270.
[0062] Schematically illustrated in cross-section in FIG. 9 is an
aircraft aft FLADE engine 1 having a fan section 115 with first and
second counter-rotatable fans 130 and 132. The variable first FLADE vanes
6 are used to control the amount of a FLADE airflow 80 allowed into the
FLADE inlet 8 and the FLADE duct 3. Opening of the FLADE duct 3 by
opening the first FLADE vanes 6 at part power thrust setting of the FLADE
engine 1 allows the engine to maintain an essentially constant inlet
airflow over a relatively wide range of thrust at a given set of subsonic
flight ambient conditions such as altitude and flight Mach No. and also
avoid spillage drag and to do so over a range of flight conditions. This
capability is particularly needed for subsonic part power engine
operating conditions.
[0063] The FLADE inlet 8 and the fan inlet 11 in combination generally
form the engine inlet 13. Downstream and axially aft of the first and
second counter-rotatable fans 130 and 132 is the core engine 18 having an
annular core engine inlet 17 and a generally axially extending axis or
centerline 12 generally extending forward 14 and aft 16. A fan bypass
duct 40 located downstream and axially aft of the first and second
counter-rotatable fans 130 and 132 circumscribes the core engine 18. The
FLADE duct 3 circumscribes the first and second counter-rotatable fans
130 and 132 and the fan bypass duct 40.
[0064] One important criterion of inlet performance is the ram recovery
factor. A good inlet must have air-handling characteristics which are
matched with the engine, as well as low drag and good flow stability. For
a given set of operating flight conditions, the airflow requirements are
fixed by the pumping characteristics of the FLADE engine 1. During
supersonic operation of the engine, if the area of the engine inlet 13 is
too small to handle, the inlet airflow the inlet shock moves downstream
of an inlet throat, particularly, if it is a fixed inlet and pressure
recovery across the shock worsens and the exit corrected flow from the
inlet increases to satisfy the engine demand. If the FLADE engine inlet
area is too large, the engine inlet 13 will supply more air than the
engine can use resulting in excess drag (spillage drag), because we must
either by-pass the excess air around the engine or "spill" it back out of
the inlet. Too much air or too little air is detrimental to aircraft
system performance. The FLADE fan 2 and the FLADE duct 3 are designed and
operated to help manage the inlet airflow delivered by the inlet to the
fans.
[0065] The core engine 18 includes, in downstream serial axial flow
relationship, a core driven fan 37 having a row of core driven fan blades
36, a high pressure compressor 20, a combustor 22, and a high pressure
turbine 23 having a row of high pressure turbine blades 24. A high
pressure shaft 26, disposed coaxially about the centerline 12 of the
engine 1, connects the high pressure compressor 20 and core driven fan 37
to the high pressure turbine 23 with the high pressure turbine blades 24.
The core engine 18 is effective for generating combustion gases.
Pressurized air from the high pressure compressor 20 is mixed with fuel
in the combustor 22 and ignited, thereby, generating combustion gases.
Some work is extracted from these gases by the high pressure turbine
blades 24 which drives the core driven fan 37 and the high pressure
compressor 20. The high pressure shaft 26 rotates the core driven fan 37
having a single row of circumferentially spaced apart core driven fan
blades 36 having generally radially outwardly located blade tip sections
38 separated from generally radially inwardly located blade hub sections
39 by an annular fan shroud 108.
[0066] The combustion gases are discharged from the core engine 18 into a
low pressure turbine section 150 having counter-rotatable first and
second low pressure turbines 19 and 21 with first and second rows of low
pressure turbine blades 28 and 29, respectively. The second low pressure
turbine 21 is drivingly connected to the first counter-rotatable fan 130
by a first low pressure shaft 31, the combination or assembly being
designated a first low pressure spool 242. The first low pressure turbine
19 is drivingly connected to the second counter-rotatable fan 132 by a
second low pressure shaft 30, the combination or assembly being
designated a second low pressure spool 240. The second counter-rotatable
fan 132 has a single row of generally radially outwardly extending and
circumferentially spaced-apart second fan blades 32. The first
counter-rotatable fan 130 has a single row of generally radially
outwardly extending and circumferentially spaced-apart first fan blades
33. The aft FLADE fan blades 5 are primarily used to flexibly match inlet
airflow requirements.
[0067] The high pressure turbine 23 includes a row of high pressure
turbine (HPT) nozzle stator vanes 110 which directs flow from the
combustor 22 to the row of high pressure turbine blades 24. Flow from the
row of high pressure turbine blades 24 is then directed into
counter-rotatable second and first low pressure turbines 21 and 19 and
second and first rows of low pressure turbine blades 29 and 28,
respectively.
[0068] A row of fixed low pressure stator vanes 66 is disposed between
the second and first rows of low pressure turbine blades 29 and 28.
Alternatively, a row of variable low pressure stator vanes may be
incorporated between the second and first rows of low pressure turbine
blades 29 and 28. The first low pressure turbine 19 and its first row of
low pressure turbine blades 28 are counter-rotatable with respect to the
row of high pressure turbine blades 24. The first low pressure turbine 19
and its first row of low pressure turbine blades 28 are counter-rotatable
with respect to the second low pressure turbine 21 and its second row of
low pressure turbine blades 29. The aft FLADE turbine 160 is illustrated,
in FIG. 9 as a free turbine not connected to a spool or fan in the fan
section 115. Alternatively, the aft FLADE turbine 160 may be drivingly
connected to the first low pressure shaft 31 of the second low pressure
spool 242.
[0069] The total flow available for vectoring is set by the rotational
speed of the aft FLADE fan and the setting of the variable first FLADE
vanes 6. The right and left hand valves 162 and 164 control flow to the
right and left hand FLADE exhaust nozzles 125 and 135 and control the
total pressure ratio at which the aft FLADE turbine 160 and aft FLADE fan
2 operate. The turbofan engine operating conditions may be modulated as
necessary to provide the desired combination of overall propulsion system
thrust and vectoring forces. Turbofan engine controls would be modified
or configured to react to the demands of the thrust vectoring system.
This may be achieved by biasing existing control schedules based on the
variable first FLADE vane 6 and the right and left hand valves 162 and
164 settings. Alternatively, the primary control mode for the turbofan
may be modified such as replacing the typical fan speed control with a
system that controls the pressure ratio between an exit of the aft FLADE
turbine 160 and the fan inlet 11 of the aircraft aft FLADE engine 1.
[0070] The engines illustrated herein are single and double bypass types
and it is thought that a turbojet type may be used in which there is no
bypass duct or bypass flow and the aft FLADE turbine would be placed
downstream of any turbine section used to drive the fan and/or
compressor. Turbojet type engines may also use augmenters and variable
area two-dimensional nozzles.
[0071] 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.
* * * * *