FR2525688A1 - NOZZLE FOR TURBOMACHINE - Google Patents

Abstract

THIS EXHAUST PIPE FOR A GAS TURBINE AIRPLANE ENGINE INCLUDES A 17C DUCT, SEVERAL MOVABLE SHUTTERS 38, 43 TO MODIFY THE GEOMETRY OF THE TUBE, ONE OR SEVERAL OPENINGS 59 DIRECTED FORWARD AND OUTDOOR, ARRANGED UPSTREAM OF SHUTTERS 38, 43 AND A PAIR OF DOORS 61 IN MUTUAL CONFRONTATION, EACH OF WHICH IS ROTATING AROUND AN AXIS EXTENDING TRANSVERSALLY THE LENGTH OF DUCT 17C. THE DOORS 61 ARE LOCATED, IN RELATION TO THE DUCT 17C AND TO THE OPENINGS 59, SO THAT IN A FIRST POSITION THEY CLOSE THE OPENINGS 59 AND THE SURFACES IN MUTUAL CONFRONTATION 67 OF THE DOORS DEFINE BETWEEN A PART OF THE COURSE OF THE GAS CURRENT THE TUBE, AND THAT THE DOORS 61 CAN BE MOVED TO A SECOND POSITION, UPSTREAM OF THE FIRST POSITION, WHERE THEY DISCOVER THE OPENINGS 59, DEFINING AT THEIR UPSTREAM ENDS 68 A REDUCED PASSAGE SECTION NECK FOR THE GAS CURRENT COURSE BY THE PIPE. IN THE SECOND POSITION, THE GATES 61 ALSO DEFINE A DIVERGENT PART OF THE ROUTE FOLLOWED BY THE GAS CURRENT IMMEDIATELY DOWNSTREAM OF THE PASS. THE REDUCED PRESSURE GOING DOWNSTREAM OF THE NECK ATTRACTS AMBIENT AIR THROUGH THE OPENINGS 59 AND IN THE COURSE FOLLOWED BY THE GAS CURRENT PASSING THROUGH THE PIPE.

Description

The present invention relates to nozzles for mo-

  gas turbine airplane torers and particularly concerns

  variable geometry nozzles and the elimination of

  infrared diations emitted by the hot jet of gas

  exhaust of these engines. Modern fighter jets demand flexibility

  to be able to fly at subsonic and supersonic speeds

  ques and thus fulfill various functions To fulfill

  these functions you have to increase the basic thrust pro-

  delivered by the engine in "dry" mode by burning additional fuel downstream of the engine turbines, using the unburnt oxygen contained in the exhaust gases At to

  support combustion This mode is known as re-

  heating or post-combustion During heating, it is necessary to increase the section of the nozzle to admit the larger volume of gas and not to harm

  for efficient engine operation For other functions

  such as a supersonic cruise, it is desired

  table to modify the geometry of the engine exhaust nozzle starting from a converging geometry suitable for a subsonic speed to arrive at a configuration where the section of the neck is larger (compared to that which is necessary during the " dry "or for a subsonic cruise), this neck being formed between the converging part and the diverging part of the nozzle, at which

  reference is often made to the expression "nozzle"

vergente-divergente "(con-di).

  There are times during the flight envelope of an aircraft when warming is not necessary and or

  the essential condition is to reduce infrared emissions

  red of the exhaust gas jet and thereby reduce or even avoid detection by research missiles of

  heat going to the plane These missiles detected

  usually try infrared emissions from the hot jet

  exhaust gas and when the jet is detected,

  laugh at the hot parts of the engine to destroy the plane. There is a need for a nozzle which may not only be suitable for dry operating modes

  and in reheating, but also allowing to reduce se-

  the infrared emissions from the engine.

  An object of the present invention is to provide a variable geometry nozzle capable of being used both for dry and reheating modes of operation, and also capable of reducing the infrared emissions of the jet.

hot exhaust gases.

  The invention as claimed makes it possible to

  define the geometry of the nozzle to fit as well

  dry and reheat operating modes,

  placing shutters and reducing infrared emissions

  red by opening additional air inlets which admits

  try the ambient air in order to cool and mask the jet

hot exhaust gases.

  The nozzle according to the present invention can be installed

  mounted on a fixed jet tube or on a movable jet tube In addition, the nozzle of the present invention can be installed on the steerable nozzles of an engine such as the engine

  Pegasus of Rolls-Royce Llmited which discharges air from drift

cold or warmed food.

  The invention will now be described by way of example and with reference to the attached drawing, in which FIG. 1 schematically represents an aircraft engine with a gas turbine comprising three directional nozzles Par

  convenience, only one of the nozzles constituted according to the present

the invention is represented.

  Figure 2 shows in more detail a sectional and elevation view of part of the rear nozzle of the engine shown in Figure 1; Figure 3 shows in more detail a part of the series of first flaps of the nozzle of Figure 2;

  Figure 4 shows in more detail the ejection nozzle

  tion constituted according to the present invention, and Figure 5 shows a modification of the doors in

  shape of the nozzle shells shown in Figure 4.

  If we refer to Figure 1, it represents a diagram

  materially an aircraft turbine engine (10) of the bypass type The engine comprises in series a low pressure and axial flow compressor (11), a high pressure and axial flow compressor (12), a combustion

  (13), a high pressure turbine (14) which drives the com-

  HP presser (12), a low pressure turbine (15) which drives the LP compressor (11), and a jet tube (16) which

  ends in a nozzle (17) of variable and orientable section

  corn. The LP compressor (11) sends compressed air to the HP compressor (12) and to a plenum chamber (18) which is part of the bypass line (19) and

  which ends with two adjustable nozzles (20)

  eyes (20) are mounted in bearings (25), so as to

  turn on an angle of about 1100 around an axis (21).

  Additional combustion equipment (22) is provided in the still chamber (18), so that additional fuel can be burnt in the air stream which is discharged through the nozzles (20), in order to increase the push To allow the engine to run

  effectively, the nozzles (17) and (20) are provided with outlets

  parts with variable geometry and variable section, and

  trout according to the present invention.

  For convenience, the invention will be described more particularly

  with reference to the nozzle (17), but it will be understood

  that the mechanism used to modify the section and ge-

  ommetry is similar for all nozzles (17) and (20), and can also be used with tube nozzles

fixed jet.

  The nozzle (17) is of the type in which a built-in rotary pipe (17 a) is mounted in bearings (23) at

  the downstream end of the jet tube (16), and a second pipe

  recessed (17 b) is mounted in bearings (24), ma-

  to turn in the opposite direction to that of the pipe (17 a).

  The bearing (24) can, for its part, rotate as a whole on pins (26) extending transversely to the axis of the pipe (17b) This type of nozzle is described in more detail in the patent application Associated US NO 376 388, entitled "Vectorable Nozzles for Turbomachines' (inventive nozzles for turbomachines)

  Gary Frank Szuminski and Thomas John Jones In operation-

  the bearing (24) rotates around the axis of the trunnions

  (26) under the action of a screw jack, designated schematically-

  ment by (50), which exerts a thrust on the brackets supporting the bearing (24) deigs the toerillons (26) When the bearing (24) is rotated about the axis of the

  pins (26), the lines (17 a) and (17 b) are driven

  born in reverse rotation by a motor (51) and sprockets (52, 53), drive chains (54,55) and a flexible drive shaft (56), as explained in

  US patent application mentioned above.

  The nozzle (17) comprises at its downstream end a connector

  pick (17 c) supported by the fixed bearing track.

  It is this line (17 c) which is provided with the per-

  modifying the geometry and the outlet section of the nozzle (17) according to the present invention, as shown in

Figures 2 and 3.

  If we refer to Figures 2 and 3, the mechanism u-

  used to modify the geometry and section of the tile

  outlet, comprises an annular member (28) which can be driven in a translational movement and on which are

  supported three sets of shutters, as will be described below

  underneath The member (28) is mounted so as to slide axially

  Lement inside the downstream end pipe (17 c), and the member (28) is in the form of a hollow box

  and annular, one face (29) of which extends in the transverse direction

  versale At the axis (30) of the pipe (17 c) Gas under pressure

  sion which passes through the pipe (17 c) acts on the face (29),

  so as to urge the member (28) backwards.

  The member (28) slides inside the bore of the pipe (17 c) and a jacket (31) for protection against heat is provided to protect the pipe (17 c) and the member (28) hot gases passing through the nozzle, when the combustion chamber heats up (32), located in the

jet tube, is on.

  The member (28) is supported on tubes (33),

  axially stretching, supporting an annular cam assembly

ring (34).

  A control screw of a screw jack which is located in at least some of the tubes (33) cooperates with a nut

  (36) (of the ball and recirculation type) fixed to the member (28).

  The rotation of the control screws (35) by a motor drive and by gearboxes

  transmits to the member (28) a back and forth movement

axial rection.

  The cam-ring assembly (34) comprises two polygonal tube frames (34a) interconnected by several cams

  (37) facing inward (of which only one is

  cams (37) are located at equal distances

around the axis (30).

  A set of first primary flaps (38) are attached

  pivotally to the member (28) Each first flap

  mayor (38) is pivotally attached by its end a-

  mounted at the downstream internal circumferential end of the member (28) and it comprises a flange (39) projecting on its side which is turned towards the outside The flange (39) carries a cam follower device (40) having the form of a roller, which is in engagement with one of the cams (37) to define and modify the attitude of the flap (38) relative to the member (28), when this member (28) is moved

in axial direction.

  The flaps (38) have a hollow structure with spaced walls

  cées, made of a carbon-carbon material, such as "Pyrocarb" (trademark registered in the USA, material manufactured by Hitco in the USA) The materials in "Pyrocarb" include a carbon matrix in which a woven fabric is embedded of carbon fibers The material is protected from oxidation, by being coated with a non-oxidizing protective layer or by being impregnated with silicon, and this silicon being converted into

silicon carbide.

  A second primary flap (43) is pivotally attached

  aunt by its upstream end to the downstream end of each first primary flap (38) Each flap (43) has a hollow structure with spaced carbon-carbon walls similar to that of the flaps (38), and each flap (43) comprises one leg (42)

halfway along its length.

2525688-

  The flaps (38) are circumferentially spaced and each of the interstices between flaps (38) is closed by a thin closure plate (41) (see FIG. 3 which is a cut section passing through the hinge between flaps (38) and l (28)) The shutter plates (41) are located on the side of the flaps (38) which faces inward and are retained by rollers (46) which engage with the external surface of the flaps ( 43), so as not to

  fall inward The cover plates (41) may

  wind adapt to various positions of the flaps (38), sliding

circumferentially.

  A series of spacers (44) are fixed in a pi-

  voting by one of their ends at the external circumference and downstream of the member (28) Each of the spacers (44) is pivotally connected by its external end

  At the tab (42) of one of the second flaps (43).

  Again, the second flaps (43) are spaced apart

  and the interstices formed between them are closed by thin carbon-carbon sealing plates,

  pivotally attached at their ends,

  downstream end of the cover plates (41) The cover plates

  turation of the second flaps (43) are arranged on the side of the flaps (43) which faces inward and they are retained by rollers (71) mounted on flanges projecting through interstices between flaps (43), so as to come into engagement with the external surface of

  flaps (43) and to prevent them from falling inwards.

  The shutter plates of the second flaps (43) allow these flaps to occupy various positions where they define a converging part of the nozzle up to the point where they define a diverging part of the nozzle by sliding relative to the flaps (43 ) Said blanking plates

  have no legs (42), and there is no

  rods (44) connected to these blanking plates.

  A set of third flaps (47) made of a material

  polyimide reinforced with carbon fibers are pre-

  seen on the member (28) Each of the third flaps (47) is pivotally attached by its upstream end to the downstream end of the member (28), and is pivotally attached by its downstream end to the downstream end of one of the second flaps (43) The pivot (45) which is at the upstream end of the third flaps (47) is disposed in an elongated hole (46) made in the member (28).

  The flaps (47) overlap to adapt to the di-

verses positions of the flaps (43).

  When the nozzle is operating and when the member (28) is in its position completely at the rear, position

  which is shown in solid lines in FIG. 2, the vo-

  lets (38) define a converging part of the nozzle and

  the flaps (43) define a parallel or light part-

  divergent from the nozzle with minimum dimension for the

  neck region of said nozzle (in a radial plane of the

  pivot connections between flaps (38) and (43) This confi-

  guration could be used for a maximum dry thrust operating mode in subsonic flight, for example for

  takeoff, or for subsonic accelerations.

  When the member (28) is pulled forward, the cam follower elements (40) move along the cams (37), and

  the flaps (38) define a parallel or light part-

  converging nozzle (shown in phantom)

  with a maximum neck section, and the flaps (43) defi-

  connect a divergent part of the nozzle, with a maximum outlet section at the downstream ends of the flaps (43) This

  configuration could be used for a ma-

  ximal in heating mode or in CC T. When the flaps (38) and (43) occupy different positions, their closure plates slide so as to fill the gaps between their respective flaps The flaps (47) also move to change the angle of

  shrunk pellet and thereby reduce pellet drag.

  The loads applied by the gases on the flaps (38) and (43) and their closure plates, are retransmitted to the member (28), and they exert a net force towards the front '(i.e. - say towards the jet tube (16) on the organ

  (28) Consequently, when exposing the front face of the

  gane (28) to pressurized gases passing through the pipe (17 c), the gases exert a force directed towards the rear on

  the member (28), which partially counterbalances the charges in

  rection from the front, exerted on the member (28) This in turn reduces the forces necessary to move the member (28) in the axial direction You can choose the surface of the face

  front (29) of the member, so as to obtain an optimum force

  male directed rearward and applied to the organ (28).

  It is clear that for intermediate positions

  between those which are represented in solid and mixed lines-

  In Figure 2, you can get various combinations of

  convergence and divergence with various neck sections.

  Referring to FIG. 4, the pipe (17 c) is provided with outlet openings (59) directed towards the front and

  circumferentially spaced A cy-

  indric and hollow (60), capable of undergoing a movement of

  axial lation, is provided to seal the outer end of all the outlet openings (59) A pair of doors (61) in the form of frustoconical and hemispherical shells which pivot around a transverse axis (62) of the pipe

  (17 c) is provided to seal the internal ends of the

  exit vertices when the doors (61) are in a po-

  stowed position, shown in broken lines.

  In the stowed position, the facing surfaces (67) of the doors (61) define between them a part of the path of the gases passing through the nozzle (17) A motor (66) is provided to rotate the doors (61) in the forward direction around

  axis (62), from the stowed position to a second position

  tion (ejection position) upstream of the openings (59) By moving the doors (61) to the ejection position, they uncover the openings (59), and simultaneously the front edges (68) of the doors form a barrier defining a

  neck with reduced passage section for gaseous flow

  through the nozzle, immediately upstream of the openings (59).

  The confronting surfaces (67) of these doors define

  also a divergent part of an immersed primary nozzle

  directly downstream of this reduced section neck The depression

  ensuing sion which is caused by the gas flow downstream of the neck, attracts ambient air through the openings (59) and passes it through the nozzle, so as to cool and

  mask the jet of hot gases emitted by the nozzle.

  When the doors (61) are deployed in position

  ejection, the member (28) is moved rearwardly

  Lesson to move the flaps (38) and thereby increase the passage section of the neck of the secondary nozzle formed by the flaps and allow the passage of the larger air stream from the ambient air which has been attracted by the openings (59) It will be seen that, when the doors are stowed, the effective nozzle of the engine is that which is defined by the flaps (38), but that, when the doors are in the ejection position, the nozzle which controls the cycle thermodynamics of the engine is that formed by the

doors (61).

  The door (60) forming a cover is supported concentrically

  three times relative to the bearing (24) by means of eight

  gnons (63), circumferentially spaced and engaged with racks (64) on the inner circumference of the

  door forming cover (60) The pinions (63) are entrained

  born by a motor (65) which drives all the pinions (63) by

  through gear boxes and drive shafts

  ment (not shown), so as to rotate in unison and

  move the door (60) axially to open and close

  sea the outer ends of the openings (59).

  The drive of the pinions (63) is synchronized with that of the shell-shaped doors (61), so that the door (60) is moved in order to open the openings (59) only when the shell-shaped doors (61)

  are moved to the eject position In addition, the

  drag going to the mechanism that moves the axial organ-

  ment to modify the geometry of the nozzle, is synchronized so that, when the shell-shaped doors (61) are moved to the ejection position, the flaps (38) are moved so as to increase the passage section of the neck

  which is defined by the flaps (38).

  It cannot be stressed too strongly that, although the nozzle described above has been with reference to an adjustable nozzle, the present invention can be eminently valid at the end downstream of a tube

fixed jet.

  Referring to FIG. 5, the section of the neck defined by the upstream edges (68) of the doors (61) can be increased or modified so as to increase the current

  of ambient air ejector and the mixing potential deter-

  undermining openings (69) in each of the doors (61), the openings (69) being covered by flaps (70) on the

  face (67) of each door (61) which faces inward

  These shutters are constructed so as to open under the effect of the draft when the doors (61) are

  in the ejection position, and they are kept closed in

  sition stowed by the pressure of the gases acting on the

  ts shutters (70) Alternatively, it might be possible to

  screw and close the flaps (70) by mechanical means It will be seen on examining FIG. 4 that by reversing the

  motor (66), the doors (61) can be turned in the direction

  downstream to a third position where they uncover the openings (59) and cooperate with the flaps (38) (when

  they are arranged in a converging position).

  An important feature of the present invention is that the shell-shaped doors (61) are provided at the nozzle neck. In other words, the doors

  (61) cooperate with the flaps (38) when they are deployed

  in order to form a converging pipe, as is

  the case when the engine is used in subsonic "dry" mode.

  The drive to the gables (63) is synchronized with the drive to the shell-shaped doors (61), so that the door (60) is moved and opens the openings

  (59) when the shell-shaped doors (61) are

  placed towards their reverse thrust position In addition, the drive going to the mechanism which moves the member (28) axially, in order to modify the geometry of the nozzle, is synchronized so that the shell-shaped doors (61) cannot be moved to the push position

  reversed only when the flaps (38) are in the con- position

  vergente (that is to say when the member (28) is pushed backwards to the maximum and when the engine is running in

"dry" subsonic).

  By placing the shell-shaped doors (61) in the region of the nozzle neck and using the flaps (38)

  to facilitate the formation of part of the surface of

  bending during reverse push mode, it is possible to have smaller shell-shaped doors (61) which are therefore lighter and easier to deploy. This is particularly important when a reverser is required.

  thrust in an adjustable nozzle.

Claims (9)

CLAIMS -   1 Exhaust nozzle for turbine aircraft engine   gas, comprising a pipe (17 c), several dampers   balls (38,43) to modify the geometry of the nozzle, one or more openings (59) directed forwards and outwards and arranged upstream of the flaps (38,43), and a pair of doors (6 i) in mutual confrontation, of which   each is rotatably mounted around an axis spanning   tending transversely to the length of the pipe (17 c), characterized in that the doors (61) are arranged by   compared to driving it (17 c) and to the openings (59),   nière such that, in a first position, they close the openings (59), and that the surfaces in mutual confrontation (67) of the doors define between them a part of the course followed by the gas current in the nozzle, the doors (61) can be moved to a second position, upstream of the first position, where they uncover the openings (59), define at their upstream ends a neck of reduced section for the path of the gas stream   by the nozzle, and also define a different part   gente of the course of the gas stream immediately downstream of said neck, thereby reducing the pressure downstream of the neck to pass ambient air through the openings (59), and make it penetrate into the course of the gaseous stream which passes   by the nozzle, and means (28,36) being provided for   place the flaps (38,43), in order to pass the current   more gaseous through the nozzle when said openings tures (59) are discovered.   2 nozzle according to claim 1, characterized in   that the doors (61) can be moved to a third   sth position, -downstream of the first position, where the   your discover said openings (59), and cooperate with the flaps (38,43), when the flaps are in a position of convergence, so that the flaps, with the doors,   determine deflection surfaces that redirect the cou-   rant of gases and brings it out through said openings.   3 Nozzle according to claim 1 or the   claim 2, characterized in that a second device   door frame (60) is provided to close off one end   external of the or each opening (59).   4 Nozzle according to claim 1 or the resale   dication 2, characterized in that the means for moving the flaps (38,43) comprise a member (28) capable of translational and movable movement in a direction extending along the length of the pipe,   and in that the flaps (28,43) are mounted in a pi-   voting on this member (28), by their upstream end.   Nozzle according to claim 4, characterized in that the member (28) capable of carrying out a movement of   translation is mounted so that it slides on supports   ports extending axially and in that the supports carry   tent an annular frame which defines several axially extending cam surfaces (37) spaced around the axis of the annular framework.   6 nozzle according to claim 5, characterized   in that the cam surfaces (37) face inwardly   laughing and in that each flap (38,43) is provided, on its side facing outwards, with the follower device   cam (40) which cooperates with one of the cam surfaces.   7 nozzle according to claim 4, characterized   in that the flaps (38,43) comprise a symmetrical series   that with respect to the axis of first flaps (38) and in that there is further provided a series, symmetrical with respect to the axis, of second flaps (43), each of which is pivotally mounted by its upstream end to downstream end   of one of the first strands, and in that means of re-   held (44), are provided to force the second flaps to occupy a divergent position relative to the pipe,   in at least one position of the second flaps.   8 nozzle according to claim 7, characterized in   that the retaining means include several maintenance   its (44), each of which is pivotally fixed by a   end to the member (28), carrying out a movement of   axial lation and is pivotally fixed by its other   end at one of the second flaps.   9 nozzle according to claim 6, characterized in that there is provided a series, symmetrical with respect to the axis, of third flaps (47), each of the third flaps being pivotally connected by its downstream end to the downstream end a second flap (43), and mounted by its upstream end   on the member (28), capable of carrying out a movement of trans- axial lation.   Nozzle according to claim 5, characterized in that the member (28) capable of carrying out an axial translation movement, has an annular, cylindrical and straight structure, and in that the first flaps (38) are pivotally mounted on a internal circumference of the annular member (28), and in that the third flaps (47) are pivotally mounted on an external circumference of this annular organ.   11 Nozzle according to claim 1, or the claim   cation 2, characterized in that the doors (61) include openings which are covered by shutters (70) which   are open when losses are in the second posi-   that are closed when the doors are in the   first and third positions.