United States Patent [191
`Clark
`
`[54] GAS TURBINE ENGINES
`[75] Inventor: Kenneth William Clark, Bristol,
`England
`[73] Assigneez R0l|s_Royce (1971) Limited,
`London, England
`Apr. 30, 1973
`Filed:
`Appl. No.: 355,425
`
`[22]
`[211
`
`‘
`
`[301
`
`Foreign Application Priority Data
`May 9, I972
`Great Britain .................. .. 21659/72
`
`US. Cl. ........................ .. 239/265.31, 60/226 A
`Int. Cl ............................................. .. F02k 3/04
`Field of Search..... 239/2651], 265.31, 265.13;
`60/264, 271, 226 R, 226 A
`
`[52]
`[51]
`[58]
`
`[56]
`
`References Cited
`UNITED STATES PATENTS
`l0/l962 Kuzyk ................................. .. 60/264
`
`3,058,302
`
`3,820,719
`[11]
`[45] June 28, 1974
`
`3,508,517
`
`4/1970 Hannan ........................... .. 60/271 x
`
`Primary Examiner-Ml-lenson Wood, Jr.
`Assistant Exammer-—Michael Y. Mar
`Attorney, Agent, or Firm-Stevens, Davis, Miller &
`Mosher
`
`[57]
`A fan type gas turbine engine for use in an aircraft,
`the engine having a fan cowl comprising at least two
`annular parts, one part being axially separable from
`the remainder of the fan cowl to provide an annular
`opening giving additional nozzle area during take-off
`conditions and being shaped to promote attachment of
`the extra nozzle flow to its outer surface; and, if the
`fan is a variable pitch fan, the additional nozzle area
`can serve as additional intake area for the fan during
`operation in the reverse pitch mode.
`
`8 Claims, 10 Drawing Figures
`
`GE v. UTC
`IPR2016-00952
`GE-1028.001
`
`

`

`PATENTEDJuuw m4
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`3.82U.7l9
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`SHEET 1 BF 5
`
`Tel
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`GE v. UTC
`IPR2016-00952
`GE-1028.002
`
`

`

`”me28 W4
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`3820.719
`
`SHEET 2 OF 5
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`
`
`GE v. UTC
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`|PR2016-00952
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`GE-1028.003
`
`GE v. UTC
`IPR2016-00952
`GE-1028.003
`
`

`

`PATENTEBJIJRBB mm
`
`3320 71s
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`SHEET 3 0F 5
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`FIGE‘
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`FIGS
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`GE v. UTC
`IPR2016-00952
`GE-1028.004
`
`

`

`PATENTEI] JUN 2 8 I974
`
`3.820.719
`
`saw u or 5
`
`GE v. UTC
`IPR2016-00952
`GE-1028.005
`
`

`

`FATEHTEBJMB m4
`
`3.929.719
`
`SHEET 5 BF 5
`
`mom v
`
`or OI
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`GE v. UTC
`IPR2016-00952
`GE-1028.006
`
`

`

`1
`GAS TURBINE ENGINES
`
`3,820,719
`
`20
`
`25
`
`This invention relates to nozzles for gas turbine en~
`gines, and relates in particular to nozzles for variable
`pitch fan gas turbine engines.
`In a variable pitch fan engine a fan delivers com
`pressed air to a bypass duct formed between a cowling
`surrounding the fan (a fan cowl) and a core engine
`which drives the fan. The pitch of the fan blades may
`be varied to match the performance of the engine to
`the ?ight envelope of an aircraft in which it is installed.
`Thus for take off conditions the fan blades are set in
`coarse pitch and deliver the maximum amount of air
`through the bypass duct, for cruise conditions the
`blades are set to a finer pitch and deliver a lesser
`amount of air through the duct, and, on landing, re»
`verse pitch is selected to reverse the direction of ?ow
`through the duct and exert a braking force on the air
`craft. In such engines it is necessary to alter the cross
`sectional flow area of the nozzle formed between the
`end of the fan cowl and the core engine to suit the pitch
`of the fan blades, and in particular this nozzle must act
`as an auxiliary intake for the engine when it is operating
`in the reversed pitch mode.
`According to this invention a nozzle for a gas turbine
`engine comprises a cowl which de?nes the nozzle area
`and which includes a ?xed portion and a portion axially
`movable in relation to the ?xed portion to form an
`opening thereby de?ning additional nozzle area, and
`wherein the surfaces forming the opening are shaped to
`direct ?ow through the opening and to promote attach
`ment of said flow to the surface of the cowl.
`Preferably the gas turbine engine is a ducted fan en
`gine in which the cowl de?nes the fan duct.
`In one embodiment of the invention the gas turbine
`engine is a variable pitch fan engine.
`In a variable pitch fan engine the opening in the fan
`cowl may serve as an intake when the fan is operating
`in the reversed thrust mode.
`The size of the opening when operating as an intake
`may differ from its size when operating as a nozzle.
`Thus, a nozzle for a variable pitch fan engine may
`comprise a fan cowl, which de?nes the nozzle area, and
`which includes a fixed portion, and a portion axially
`movable in relation to the ?xed portion from a ?rst po
`sition in contact with the fixed portion, to a second po
`sition, in which it is axially spaced therefrom, and
`which is further movable to a third position in which it
`de?nes an intake for the engine, when said engine is op
`erating in the reversed pitch mode.
`Also according to this invention a nozzle for a vari
`able pitch fan engine comprises a cowl which defines
`the nozzle area and includes an upstream portion and
`relatively axially movable ?rst and second downstream
`portions and wherein the second downstream portion
`is separable from the upstream and the first down
`stream portions to provide additional nozzle area and
`the ?rst downstream portion is separable from the up
`stream portion to de?ne an opening which provides ad
`ditional intake area during reversed pitch operation of
`the fan.
`,
`An embodiment of the invention will now be de
`scribed by way of example only with reference to the
`accompanying drawings wherein:
`FIG. 1 is a longitudinal section through a variable
`pitch fan engine showing a nozzle constructed in accor
`dance with the invention,
`
`2
`FIG. 2 is a half section through the nozzle of the en
`gine of FIG. 1 shown in a first operating position,
`FIG. 3 shows a second operating position of the noz
`zle of FIG. 1,
`FIG. 4- shows a third operating position of the nozzle
`of FIG. 1,
`FIG. 5 is a section on the line l-I of FIG. 1,
`FIG. 6 is a section on the line II—-II of FIG. 1,
`FIG. 7 illustrates the sealing of‘ the nozzle of the en
`gine of FIG. ll,
`FIG. 8 shows a ?rst operating position of an alterna
`tive embodiment of the invention,
`FIG. 9 shows a second operating position of the em
`bodiment of FIG. 8, and,
`FIG. 10 shows a third operating position of the em
`bodiment of FIG. 8.
`In FIG. II a gas turbine engine Ill is shown attached
`by a pylon 12 to a wing 13 of an aircraft (not shown). -
`The engine comprises a fan cowl 14 which surrounds
`a fan 15 and has a ?xed upstream portion'and an axially
`movable downstream portion 20. The pitch of the fan
`blades may be varied by means of a pitch change mech
`anism 16, the fan being driven by a core engine 17 and
`delivering air to a bypass duct 18 formed between the
`fan cowl and the core engine.
`The area of the nozzle formed by the rear part of the
`fan cowl and the core engine may be altered by trans’
`lating the movable portion 20 of the fan cowl rear
`wards. Preferably, this movable portion forms a com
`plete annulus as, in this way, the strength necessary to
`contain the gas pressures acting on the portion may
`readily be achieved by a light structure.
`_
`The annulus is translated rearwards along a guide rail
`19 from a ?rst position 21, for cruise conditions, to a
`second position 22 for take-off conditions and to a
`third position 23 during reversed thrust.
`In the ?rst position 21 the annulus abuts the ?xed
`portion of the fan cowl 24 so that its outer and inner
`surfaces 25, 26 respectively form a continuous pro?le
`with the outer and inner surfaces 27, 28 of the forward
`portion of the fan cowl. 1
`> FIGS. 2, 3 and 4 illustrate in more detail how the noz
`zle area variations alter the gas flow capacity of the
`nozzle. In FIG. 2 the annulus 20 is shown in the ?rst po
`sition lying ?ush with the fan cowl 24.
`This section is taken at a different angle through the
`engine than the section of FIG. 1 and includes one of
`four screw jacks 31 used to translate the annulus. It will
`be seen that the fan cowl is lined with sound absorbing
`material 32. An in?atable seal 33‘ prevents gas escaping
`through the space between the portions of the fan cowl
`when in the first position.
`In FIG. 3 the screw jack has been extended to sepa
`rate the two portions of the fan cowl sufficiently to per
`mit some of the air to flow down the duct in the direc
`tion shown by the arrow 41 and for the remainder to
`pass in the direction 42 and out through the opening
`40. The surfaces 34 of the portions of the fan cowl that
`form the opening 40 are so shaped that the flow
`through them attaches to the outer surface 35 of the
`movable portion, thus no drag penalty is incurred by
`the flow breaking away from the fan cowl.
`In FIG. 4 the screw jack has been further extended,
`and, with the fan operating in the reversed pitch mode,
`the direction of ?ow down the duct is reversed and the
`nozzle is now acting as an intake for the fan. It will be
`seen that additional “intake” area is achieved by the
`
`40
`
`45
`
`50
`
`55
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`60
`
`65
`
`GE v. UTC
`IPR2016-00952
`GE-1028.007
`
`

`

`3,820,719
`
`25
`
`30
`
`35
`
`3
`in?ux of air between the two portions of the fan cowl,
`in the direction 43.
`The four screw jacks 31 are of the recirculating ball
`type and driven by a ?exible drive arranged as shown
`in FIG. 5. An air motor 51 drives the jacks through a
`cable (not shown) running in a conduit 52 situated in
`the ?xed portion of the fan cowl 24. The air motor is
`conveniently housed in the space provided by the for
`ward end of the pylon 12 and the fillet fairings 53.
`Screw jacks are preferred to hydraulic ones as they
`are easier to synchronise and the arrangement shown
`provides that in the event of one of the jacks failing the
`remaining jacks will still operate effectively.
`in FIG. 6 a section through the guide rail 19 which
`guides the movement of the annulus 20 of the fan cowl
`may be seen. The pylon l2 and the associated ?llet fair
`ing 53 enclose the guide rail which comprises two
`guides 54, 55 lying parallel to’ the axis of the duct and
`connected to the pylon and each other by tie pieces 56
`disposed at intervals along the length of the guides. Be
`cause, of the pressure differential between the inside
`and outside of the duct there is a hoop stress set up in
`the fan cowl and this stress is transmitted round the cir
`cumfe'rence of the fan cowl via the tie pieces 56. In ad
`dition to the circumferential seal 56 which prevents gas
`leakage through the joint between the two portions of
`the fan cowl, it is necessary to prevent gas leakage be
`tween the fan cowl and the guide rail. H6. 7 illustrates
`how this is done.
`There are two possible paths by which gas from the
`duct can escape past the guide rails.
`The ?rst path is between the pylon 59 that supports
`the core engine and the guide rail 55 and this may be
`simply prevented by raising a ?ange 61 on the guide 55
`and a ?ange 62 on the pylon and interposing a resilient
`sealing member 63, for example a cylindrical rubber
`strip, between the two ?anges.v
`'
`The second possible path is around the tee piece 58
`that engages the guide 55. This leakage may be stopped
`by lining the guide with a resilient layer 64, of, for ex
`ample, polytetra?ouroethylene. As the guide not only
`guides the movement of the part 20 but also supports
`its weight the tee piece 58 will tend to tip in a clockwise
`direction and two line seals will be formed between the
`tee piece and the resilient layer at 65 and 66. Polytetra
`?ouroethylene is the preferred material as its lubricat
`ing properties aid the translation of the portion of the
`fan cowl.
`An alternative embodiment of the invention is illus
`trated in H05. 8, 9, 10 each of which show a half sec
`tion through a'fan cowl. This fan cowl comprises first
`and second axially movable annular portions 70, 71 ar
`ranged so that in a first position the two movable por
`tions are in close contact with a third fixed portion 72.
`When extra nozzle area is required for take off then the _
`part 71 is translated rearwards to a second position in
`which air ?owing down the duct 18 may ?ow through
`the opening 78 in the fan cowl and over its outer sur
`face 73 as indicated by the arrow 74. For reversed
`
`4
`thrust conditions, in which the direction of ?ow down
`the duct as represented by the arrow 75 is reversed, the
`portions 70 and 71 are moved together to a third posi
`tion in which they de?ne an opening 76. Air may ?ow
`in the direction of the arrows 77 through this opening
`thus providing additional intake area. The shape of the
`surfaces de?ning this opening are such as to promote
`attachment of flow to the interior surface of the ?xed
`portion of the fan cowl. It will be appreciated that the
`guide rails, drives, and sealing arrangements as de
`scribed in relation to the first embodiment may readily
`be applied to this embodiment.
`It is not strictly necessary that a complete annular
`part of the fan cowl should be translated rearwards but
`this is preferred as it results in a lighter structure.
`What I claim is:
`l. A nozzle for a ducted fan gas turbine engine having
`fan cowl means de?ning the nozzle area, means for rel
`atively ‘axially separating an upstream portion and a
`downstream portion of the fan cowl means to de?ne an
`opening therebetween, means for directing a portion of
`the nozzle ?ow through said opening and for promoting
`attachment of the nozzle ?ow to the outer surface of
`the said downstream portion.
`2. A nozzle for a gas turbine engine according to
`claim 1 and wherein the said ducted fan engine com
`prises a variable pitch fan engine.
`3. A nozzle for a gas turbine engine according to
`claim 2 and wherein the said opening in the fan cowl
`means de?nes intake means for reversed thrust opera
`tion of the fan.
`4. A nozzle for a gas turbine engine according to
`claim 3 wherein the size of said opening when operat
`ing as a nozzle differs from the size‘ of said opening
`when de?ning intake means for reversed thrust opera
`tion of the fan.
`5. A nozzle according to claim 1 and comprising
`guide rail means for supporting one of said upstream or
`downstream portions for movement relative to the
`other of said portions.
`6. A nozzle according to claim 1 and comprising re
`circulating ball jack means for separating the said up
`stream and downstream portions.
`7. A nozzle according to claim 1 and including seal
`ing means between the said axially relatively separable
`portions.
`8. A nozzle for a variable pitch fan engine comprising
`a fan cowl which together with a core engine de?nes
`the nozzle area, the fan cowl having an upstream por
`tion and ?rst and second downstream portions charac
`terised in that there is provided means for relatively ax
`ially separating the second downstream portion from
`the upstream and ?rst downstream portion to provide
`additional nozzle area and means for separating the
`first and second downstream portions from the up
`stream portion to de?ne an opening, the opening de?n
`ing intake means for reversed thrust operation of the
`fan.
`
`40
`
`45
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`65
`
`>i=
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`*
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`*
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`*
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`*
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`GE v. UTC
`IPR2016-00952
`GE-1028.008
`
`