Note: Descriptions are shown in the official language in which they were submitted.
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E~ST NOZZLE HINGE
The invention described herein was made in the course of, or
under, United State~ Department of the Air Force Contract No.
F33657-83-C-0281. The United States Government has rights in this
invention pursuant to said contract.
BACRGROUND OF THE INVENTION
Field of the Invention
The present invention relates to hinges for pivotably
connecting axially adjacent upstream and downstream wall sections
of a gas turbine engine exhaust nozzle, and particularly to a
nozzle hinge having a novel configuration for transferring cooling
air from the upstream wall section to the downstream wall section.
Description of the Related Art
Maneuverability of modern high performance aircraft is
greatly enhanced by extending the role of ~he engine exhaust
nozzle beyond its con~entional jet accelerating function. An
exhaust nozzle with jet deflection capability can produce more
; rapid aircraft maneuvers at lower fligh~ speeds than can be
achieved by conventional control surfaces. In addition, reverse
~;~ thrust capabllity incorporated within the exhaust nozzle can
~; 20 enable the aircraft to decelerate very rapidly for in-fligh~
maneuvering purposes, and also to decelerate on landing to reduee
the landing roll for short field operation.
Exhaust nozzles capable of such additional functions are know
as multi-function exhaust nozzles. A typical such exhaust
- ~ 25 nozzle 10 is illustrated ln Fig. 1. Nozzle 10 is a two
dimensional exhaust nozzle having wall sections comprised of side
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walls 12, upstream converging flaps 14, and downstream diverging
flaps 16 and 16a disposed between side walls 12. Such two~
dimensional nozzles are preferred for multi-function applications
since, unlike round section, axisymmetric nozzles, flaps 16
S and 16a may be actuated differentially to thereby deflect the
stream of hot combustion gases exiting through the nozzle for
rapid pitch maneuvering of the aircraft. Such di ferential actu-
ation of flaps 16 and 16a is illustrated in Fig. 3. Fig. 2 illus-
trates the position of flaps 16 and 16a for normal thrust
operation. ~ig. 3 illustrates the deflected positions of flaps 16
and 16a for rapid pitch maneuvering of the aircraft. Fig. 4
illustrates a closed position of flaps 14, 16, and 16a wherein the
hot combustion gases are discharged through auxiliary exhaust
nozzles 18 to produce a reverse thrust.
Since the wall sections of the exhaust nozzles are exposed to
extremely high ~emperatures from the stream of hot products of
combustion exhausting through nozzle 10, it is preferable to cool
the interior surfaces of the wall sections to extend the service
life of the nozzle and reduce maintenance requirements.
2~ Typically, prior art nozzles utilized a surface cooling configu-
ration for the wall sections of the nozzles as illustrated in
Fig. 5. Fig. 5 schematically illustrates a portion of exhaust
no2zle lO including a casing section 20 positioned upstream of
converging flap 14 in the hot gas flow path. Casing 20 includes a
liner 22 spaced from the interior surface thereof. cooling air,
typically bypass air from the turbine engine, is injected into
; cooling air flow passage 24 between casing section 20 and
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liner 22. The cooling air is ejected from cooling air flow
passage 24 along the interior surfaces of flaps 14 and 16 to
provide a film of cooling air on the interior surfaces of those
flaps as illustrated by the arrows in Fig. 5.
However, the Fig. ~ configuration has significant drawbacks.
First, the cooling air exiting from cooling air flow passage 24 is
depleted as it flows along the surfaces of flaps 14, 16, and 16a
by mixing with hot ga~es in the exhaust gas flow path. This
depletion of the cooling air results in an excessive amount of
lo cooling air flow being required to cool the flap sections 14, 16
and 16a. Excessi.ve cooling air flow results in performance loss
since the cooling air flow is typically taken from the turbine
engine bypass air. Moreover, and with reference to Fig. 6, when
flaps 14, 16, and 16a are deflected for pitch maneuvering of the
aircraft, a severe anqle exists at the junction of the convergent
flaps 14 and divergen~ flaps 16 and 16a resulting in local flow
separation 28 downstream of throat 30. Interior surfaces of
flaps 16 and 16a, which depend on the conventional film of cooling
air injected upstream of the flap for cooling, overheat since ~he
turbulence in separated flow region 28 mixes the film of cooling
air with hot gas flowing through the exhaust nozzle and thereby
seriously diminishes the effectiveness of this type of cooling
configura~'on.
Although ~he problem of cooling nozzle wall sections is
equally applicable to axisymmetric nozzles as to multi-function,
two-dimensional type exhaust nozzles, pro~lems associated with
cooling the rearmost, divergent nozzle flap on a multi-functiOn
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two-dimensional type exhaust nozzle are magnified for two basic
reasons. First, divergent flaps on two-dimensional type nozzles
are longer for a given nozzle size and flow area than axisymmetric
nozzle flaps and, thus, are more difficult to cool by the conven-
tional method of in~ecting a f ilm of cooling air at the flaphinge. The flaps of two-dimensional exhaust nozzles are longer
than axisymmetric nozzle flaps since the-side walls of the two-
dimensional nozzle are fixed and the flap ~otion m~st therefore
provide all of the required nozzle area variation. Two-dimensional
nozzle flaps, the tips of which travel through a greater excursion
to provide the required area variation, must necessarily be longer
so that nozzle flap external contour angles are low as required
for low drag and thus high performance of the aircraft.
Secondly, and in conjunction with the reasons noted above,
during operation of a two-dimensional type exhal~st nozzle with
full jet deflection, a severe angle exists at the junction of the
con~ergent and divergent f laps resulting in local flow separation
- ~downstream of the throat as described above with reference to
FLg. 6.
In practice, two-dimensional exhaust nozzle flaps cooled by a
film of cooling air injected at the hinge are subjected to exces-
sive and nonuniform temperatures due ~o the general inefficiency
;~ of this type of film injected cooling flow. Such inefficiency has
resulted in distortion, thermal fatigue, and crackinq of the flap
surface on some exhaust nozzles currently in operational service.
Furthermore, as overall engine efficiency is increased in response
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the aircraft, the availability of bypass air for cooling the
exhaust nozzle flaps is becoming increasingly scarce. To provide
adequate temperature control of nozzle flaps on modern engines, a
more efficient convec~ion cooling means is required which, in
general, can provide for more uniform distribution of cooling air
over the wall sections of the nozzle.
Therefore, it is an object of the present invention to
provide a hinge for pivotably connecting upstream and downstream
exhaust no~zle wall sections wherein cooling air may be more
efficiently transferred from the upstream to the downstream wall
sections of the nozzle.
It is a further object of the present invention to provide a
hinge connection for adjacent upstream and downstream wall
sections of an exhaust nozzle which accommodates ~he use of liners
disposed on the interior surfaces of the wall sections of the
nozzle to define cooling air flow passages therebetween.
It is still a further object of the present invention to
- provide a hinge for adjacent upstream and downstream wall sections
of a nozzle which is capable of more efficiently transferring
-20 cooling air along the upstream and downstream interior surfaces of
the nozzle wall sections to thereby reduce the demand for cooling
air flow resulting in increased performance and efficiency of the
aircraft prime mover.
Additional objects and advan~ages of the invention will be
set forth in the description which follows, and in part will be
obvious from the desGription, or may be learned by practice of the
invention. The objects and advantages of the invention may be
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realized and attained by means of the instrumentalities and combi-
nations particularly pointed out in the appended claims.
SUMMARY OF THE INVENTION
To achieve the foregoing ob~ects, and in accordance with th~
purpo~es of the invention as em~odied and broadly described
herein, a hinge is provided for connecting a first wall section
and a second wall section of a gas turbine engine exhaust nozzle
and for allawing relatire pivoting mo~ion therebetween. The first
and second wall sections each ha~e an inside surface and a liner
attached to and spaced apart from the inside surface for defining
first and second cooling air flow passages therebetween. The
hinge comprises a curved end portion having a curved surface
formed at a first end of one of the first and second wall
sections, and leaf seal means, fixedly attached to and extending
from a first end of the other one of said first and second wall
sections, for slidably bearing against the cur~ed surface to form
-~ a substantially air-tight seal therebetween as the first and
second wall sections pirot relatire to one another. Plenum means,
defined at least in part by the leaf seal means and the first end
of the other one of the first and second wall sections, provides a
flow communication between the first and second cooling air flow
passages, and offset brac~et means are prorided for pivotably
connecting the first and second wall sections at respective first
ends of the wall sections.
Preferabl-~, the first wall section is positioned upstream of
the second wa~l section in the gas flow path through the exhaus~
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nozzle and the curred surface is formed at the upstream end of the
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second wall section. The liner of the second wall section is then
configured to include a curved upstream end portion spaced from
the curved portion of the second wall section to define a portion
of the cooling air flow passage of the second wall section. With
such a configuration, the liner of the first wall section is
configured with a downstream end portion terminating proximate to,
spaced from, and in sealing engagement with the curved end portion
of the liner of the second wall section. ~n this manner, as the
flrst and second wall sections pivot relative to one another the
curved upstream end portion of the liner of the second wall
section follows and remains proxLmate to and in sealing engagement
with to the downstream end portion of the liner of the first wall
section to maintain a continuous flow path from the first cooling
air flow pa sage, through the plenum means, to the second cooling
air flow passage without significant leaks therethrough.
BRIEF DESCRIPTION OF THE DR~NINGS
The accompanying drawings, which are incorporated in and con-
stitute a part of the specification, illustrate a preferred
; embodLment of the invention and, together with the general des-
cription given above and the detailed description of the preferred
embodiment given below, serve to explain the principles of the
invention.
Fig. 1 is a perspective view of a typical two-dimensional
converging/diverging exhaust nozzle;
Fig. 2 is a schematic side view of the nozzle of Fig. 1 with
the flaps of the nozzle positioned for full jet thrust;
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Fig. 3 is a schematic side view of the nozzle of Fig. 1 wi~h
the flaps of the nozzle deflected for pitch maneuvering of the
aircraft;
Fig. 4 is a schematic side view of the nozzle of Fig. 1 with
the nozzle flaps in a closed position to direct the exhaust gases
through auxiliary nozzles which provide reverse thrust for short
:
field operations;
Fig. 5 is a schematic side view of a conventional film type
cooling airflow configuration across convergent and divergent
lo flaps of a two-dimensional exhaust nozzle;
Fig. 6 is a schematic representation of the flow of film
cooling air across the interior surfaces of the two-dimensional
nozzle of Fig. 5 which illustrates the area of flow separation
downstream of the hinge connection when the divergent and conver-
i~
gent flaps are deflected for pitch maneuvering of the aircraft;
Fig. 7 is a detailed side view of an exhaust nozzle hingeincorporating the teachings of the present invention wherein the
wall sections of the nozzle are fully closed for reverse thrust
operation;
2u Fig. 8 is a detailed side view of the exhaus~ nozzle hinge of
Fig. 7 wherein the wall sections of the nozzle are positioned for
deflection of the exhaust gas flow path for pitch maneuvering of
.
the aircraft;
Fig. 9 is a partial isometrLc view of the exhaust nozzle
hinye of Fig. 7 illustrating the pivoting bracket connection of
the wall sections of the nozzle;
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Fig. 10 is a partial side view of the exhaust nozzle hinge of
Fig. 7;
Fig. ll is a partial top view of the exhaust nozzle hinge of
Fig. 7; and
~ ~ Fig. 12 is a schematic representation of a portion of an
- exhaust nozzle wherein hinges incorporating the teachings of the
present invention are incorporated at the connection of convergent
and divergent flaps and at the connection of the convergent flap
with the nozzle casing.
o DESCRIPTION OF THE PREFERRED EMBODIMENT
Reference will now be made in detail to the present preferred
embodiment of the invention as illustrated in the accompanying
drawings. It is here noted that the present invention is equally
applicable to axisymmetric type exhaust nozzles as to multi-
i5 function, two-dLmensional exhaust nozzles hereinbefor- described.
However, for purposes of desoribing the present preferred embodi-
- ~ ment of the invention, and not by way of limitation, the descrip-
tion below is directed primarily to a hinge incorporating the
teachings of the present invention which connects first and second
wall sections of a two-dimensional type exhaust nozzle. Further-
more, while a plurality of hLnges of the present invention may be
incorporated in a given exhaust nozzle to connect the various
pivoting wall sections, each hinge would have s~ubstantially the
same configuration, thus, only one such hinge is described herein-
below. It will be apparent to those skilled in the art that thedescription of the hinge connection f or pivoting wall sections of
the two-dLmensional nozzle is equally applicable to connections of
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wall sections of an axisymmetric type nozzle and o~her ~ariations
on multifunction type exhaust nozzles.
In accordance with the present invention, a hinge means i~
provided for connecting a first wall section and a second wall
section of an exhaust nozzle. As embodied herein, and as illus-
trated in Figs. 7 and 8, the hinge means includes a hinge
generally referred to as 100. Hinge 100 connects a first wall
~ection 102 and a second wall section 104 and allows relative
pivoting motion between first wall section 102 and second wall
lo section 104. First and second wall sections 102 and 104 each have
an inside surface 106 and 108, respectively. Wall sections 102
and 104 further include liners 110 and 112, respectively, spaced
from inside surfaces 106 and 108 to define cooling air flow
passages 11~ and 116 therebetween.
In accordance with the preqent invention, the hinge comprises
a curved portion formed at a first end of one of the first and
second wall sections. In the preferred embodiment of the present
~ invention illustrated in Figs. 7 and 8, curved portion 118 is
~; formed at a first end 120 of second wall section 104.
` 20 In accordance with the present invention, the hinge further
includes seal means for forming a substantially air tight seal
between the curved portion of the second wall section and a firs~
end of the first wall section as the first and second wall
sections pivot relative to one another. Preferably, the seal
mea~s compr~ses a leaf seal means, fixedly attached to and
extending from one of the wall sections, for slidably bearing
against the other wall section to form a substantially airtight
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seal therebetween as the first and second wall sections pivot
relative to one another. As embodied and illustrated in Fig. 7,
- the leaf seal means is fixedly attached to a first end 121 of wall
~ection 102 and includes leaf seal 122 having a root portion 124
and a biasing portion 126 cantilevered from root portion 124.
Bia~ing portion 126 includes a distal end portion 128. Root
portion 124 of leaf seal 122 is attached ~o first end 121 of wall
section 102 via a bracket 130. Root portion 124 is firmly fixed
to bracket 130 by a bolted connection 132. Alternatively, root
portion 124 may be attached to bracket 130 by welding or any other
fastening means. Bracket 130 is in turn fixedly attached to wall
section 102 by a bolted connection 134. Bracket 130 is of course
not limited to being connected to wall section 102 by bolt 134 and
may also be welded to wall section 102 or attached by any other
lS known fa~tening means. Alternatively, root portion 124 may be
fixedly attached directly to wall section 102. In the present
preferred embodiment bracket 130 serves to position and support
biasing portion 126 of leaf seal 122 in the desired position as
will be discussed hereinafter.
~; 20 With the configuration of leaf seal 122 and bracket 130 as
shown in Figs. 7 and 8, the distal end 128 of biasing portion 126
conforms to, and slidably bears against, cur~ed portion 118 of
second wall section 104 as wall sections 102 and 104 pivot
~; relatiYe to one another thereby forming an airtight seal between
-~ 25 biasing portion 126 and cur~ed portion 118.
In accordance with the present invention, the hinge further
;.: : . ,; includes plenum means, defined at least in part by the leaf seal
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means and a first end of one wall section, for flow communicating
the firs~ and second cooling air flow passages. As embodied
herein, and as shown in Figs. 7 and 8, the plenum means comprises
a plenum 136 defined a~ least in part by first end 121 of wall
section 102 and leaf seal 122. Each of wall sections 102 and 104
have a width along respective first ends 120 and 121 thereo~ sub-
stantially commensurate with one another. Liners 110 and 11~ also
have a width substantially commensurate wi~h the widths of wall
sections 102 and 104. Plenum 136 extends along substantially the
entire width of first ends 120 and 121 of first and second wall
sections 102 and 104, respectively, to form a continuous air flow
path between first cooling air flow passage 114 and sesond cooling
air flow passage 116 through plenum 136 along substantially the
entire width of wall sections 102 and 104. The airflow path of
cooling air through the cooling air flow passages and plenum is
, .~
illustrated in Fig. 7 with arrows 138. Thus, since plenum 136
connects cooling air flow passages 114 and 116 along substantially
the entire width of wall sections 102 and 104, uniform flow of
cooling air through the plenum and along the wall sections is
obtained without mixing with the hot exhaust gases exiting through
the nozzle.
In accordance with the present in~ention, the hinge further
includes offset bracket msans for pivotably connecting the first
and second wall sections at respective first ends thereof. As
embodied herein, the offset bracket means includes at least two
brackets 140. With reference to Figs. 9 and 11, bracket 140
includes a base portion 142 and an arm portion 144 extending from
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base portion 142. ~ase portion 142 is fixedly attached to first
end 121 of wall section 102 by welding or by any other suitable
fastening means. Each of the at least two brackets 140 are spaced
from one another along the width of first end 121 of wall
section 102. Arm portion 144 of bracket 140 includes a distal end
portion 146 having an aperture 148. Distal end portions 146 of
e~ch bracket are thus offse~ by the length of arm portion 144 from
wall section 102. In this manner the brackets 140 provide a con-
.~ figuration for pivotably connecting the first and second wall
sections while stepping over curved end portion 118 as discussed
below.
Ribs 1~0 are fixedly attached to wall section 104 proximate
first end 120 by welding, for ex~mple. Each pair of ribs 150 are
spaced to receive distal end portion 146 of bracket 140 therein
and includes apertures 151 which align with aper ure 148 when
: distal end portion 146 is received between ribs 150. Wall
section 104 is pivota~ly attached to distal end 146 of arm
portion 144 by means of pins 152 which extend through aperture 148
of bracket 140 and apertures 151 of ribs 150 to connect wall
sections 102 and 104 in an assemhled state.
The configuration of the offset bracket means permits wall
sections 102 and 104 to pivot relative to one another to different
: angular orientations in accordance with the opera~ing condition of
; : the nozzle while stepping over curved portion 118 of wall
section 104. In this manner, curved portion 118 remains spaced
~ ~ from first end 121 of wall s~ction 102 to partially define
::;~ plenum 136. Moreover, while Fi~. 9 illustrates at least two
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13DV-9099
brackets 140, each is substantially identical in construction,
thus, only one has been described abo~e. Furthermore, any number
of brackets 140 may be arranged along the first ends of wall
sections 102 and 104 to pivotably connect the wall sections in the
S assembled state and securely support the same. The present
invention is not limited to the specific configuration of the
bracket 140 shown and described and numerous other configurations
for the offset bracket means will be envisioned by those skilled
in the art while remaining within the scope of the present
lnvention.
With reference to Figs. 7 and 8, liner 112 of wall
section 104 includes a curved upstream end portion 154 spaced from
curved portion 118 of second wall section 104 to thereby define
the upstream-most portion of cooling air flow passage 116.
15 Liner 110 includes a downstream end portion 156 terminating
proximate to and spaced from curved end portion 154 of liner 11
to define an airflow path 158 therebetween.
Airflow path 158 between curved upstream end por~ion 154 of
liner 112 and downstream end portion 156 of liner 110 may be
' 20 dimensioned to control the amount of coolant air leakage from
plenum 136 and to eject a thin film of cooling air along the
, . .
surface of liner 112 as indicated by arrow 160. Alternatively,
hinge 100 may be configured with a means for sealing airflow
path 158. As embodied herein, the sealing means may incorporate a
. .
leaf spring 162 fixedly attached to downs~ream end portion 156 of
`~ ~ liner 110 wherein a leaf 164 of Ieaf spring 162 is configured to
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bias against curved upstream end portion 154 of liner 112 to
thereby seal airflow gap 158.
Cur~ed portion 118 of wall section 104 includes at leas~ two
notched portions 166 illustrated by dotted lines in Fig. 8.
Notched portions 165 are spaced from one another along the width
of wall section 112 to correspond to arm portions 144 of
brackets 148. Arm portions 144 are movable into and out of
notched portions 166 of curved portion 118 as first and second
~ wall sections 102 and 104 pivot relative to one another about ~he
; 10 offset bracket means. When wall sections 102 and 104 are
positioned relative to one another such that the exhaust nozzle is
in a fully deflected configuration as shown in Fig. 3, curved
upstream end portion 154 of liner 112 extends upward into
plenum 136 and arm portions 144 move into notched portions 166. In
this position the flow path of cooling air through air flow
passage 114 is into plenum 136 and then around the end of curved
upstream end portion 154 and back down and into cooling air flow
passage 116 as again illustrated by arrows 138.
~, With reference to Fig. 9, leaf seals 122 extend along the
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width of wall sections 102 and 104 and are interrupted by
brackets 140 spaced across the width of wall sec~ion 102. In this
i:
manner leaf seals 122 do not interfere with bracXets 140 as wall
sections 102 and 104 pivot relative to one another. To control
leakage from plenum 136 through notched portions 166, local
25 appendages 16B are attached to distal end 128 of cantilevered
portion 126 of each leaf seal to bridge notch portions 166 and
~, seal plenum 136 as first and second wall sections 102 and 104
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pivot about the offset bracket means to progressively larger
angles therebetween. In this manner, potential leakage loss o~
cooling air from plenum 136 is minimized by sealing notch
i portions 166 with appendages 168 as the wall sections pivot
relative to one another and curved end portion 118 of wall
section 104 for each of the angular orientations of the wall
sections. Similarly, leakage through air gap 158 between down-
stream end portion 156 of liner 110 and curved upstream end
portion 154 of liner 112 may be minimized by incorporation of leaf
spring 162 across gap 158.
A third potential leakage point of cooling air from
plenum 136 exists at the endmost connections of wall section 102
and 104 where these endmost connections abut adjoining wall
sections. To minimize leakage of cooling air from the dis~al ends
of plenum 136, an end cap 170 is attached to each distal edge of
the first end 120 of wall section 102, as illustrated in Figs. 9
; and 10, to seal plenum 136 at the ends thereof. End cap 170 fits
closely with the end of leaf seal 122 and bracket 130 to minimize
~ loss of coolant air flow between the mating surfaces thereof. To
; 20 control leakage at the interface of wall sections 102 and 104 and
a side wall 172 of the nozzle, a cylindrical seal 174 is inserted
in each endmost portion of the curved portion 118 of wall
section 104. A spring 176 may be inserted within each cylindrical
; seal 174 to bias against an abutment 177 and urge each cylindrical
seal towards a respective side wall 172 of the nozzle. Here
again, since the end caps 170 and as~ociated cylindrical seals 174
disposed at each outermost edge of wall sections 102 and 104 are
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substantially identical in construction, only one edge configura-
tion is illustrated and described herein.
In the preferred embodlment of the present invention
described hereinabove, wall section 104 comprises a diverging flap
S of a two-dimensional exhaust nozzle and wall section 102 comprises
a converging flap of the exhaust nozzle. The con~erging flap 102
i9 positioned upstream of diverging flap 104 in the exhaust gas
flow path through the nozzle. Liners 110 and 112 o~ converging
and diverging flaps 102 and 104 define a portion of the gas flow
lo path through the nozzle. However, the present invention is not
limited to use at the connection between converging and diverging
flaps of a two-dimensional nozzle. Alternatively, as illustrated
schematically in Fig. 12, the teachings of the present invention
may be incorporated at a hinge connection between a nozzle casing
lS section and the converging wall section, such as in hinge
connection 200 between nozzle casing section 202 and converging
wall section 102. A liner 204 is spaced from casing section 202
to define a cooling air flow pa~sage 206 therebetween. In this
em~odiment, cooling air flowing through passage 206 arrives in
plenum 208 at hinge connection 200 and from plenum 208 passes into
cooling air flow passage 114 along substantially the entire width
of convergen~ wall section 102 and into plenum 136 of hinge lO0.
.
; From plenum 136 cooling air flows into cooling air flow
passage l16 of divergen~ wall section 104. Thus the present
invention may be incorporated at each pivota~le connection of
respective wall sections defining the exhaust nozzle gas flow
~, path.
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Furthermore, the preferred embodiment of the present
invention has been described hereinabove with curved portion 118
formed at first end 120 of wall section 104 and with the leaf seal
means fixedly attached to and extending from first end 121 of wall
section 102. However it is well within the scope of the present
invention that the curved portion be formed at first end 121 of
wall section 102 with the leaf seal means and the offset bracket
means extending from first end 120 of wall section 104. With such
an arrangement the plenum means is still defined at least in part
by the leaf seal means and the first end of one of the wall
sections, and coolin~ air flow is directed from cooling air flow
passage 114 into plenum 136 and therefrom into cooling air flow
passage 116.
The present invention provides a novel configuration of an
exhaust nozzle hinge capable of transferring cooling air flow from
an upstream cooling air flow passage defined by a liner spaced
from the upstream wall section, to a downstream cooling air flow
passage defined by a liner spaced from the downstream wall
section. This arrangement allows for more efficient use of
~; ~o cooling air passing throuqh the cooling air flow passages and is
particularly applicable to two-dimensional exhaust nozzles wherein
the diverging flaps are of relatively long length. Through use of
the pre~ent invention avoidance of thermal distortion and fatigue,
and generally improved maintainability of the wall section5 of the
exhaust nozzle may be obtained.
- Additional advantages and modifications will readily occur to
those skilled in the art. The invention in its broadest aspects
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is, therefore, not lLmited to the specific details, representative
apparatus and illu~trative examples shown and described.
Accordingly, departures may be made from such details without
departinq from the spirit or scope of the applicants' inventive
S concept.
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