COMBUSTION GAS EXHAUST NOZZLE FOR AN AIRCRAFT TURBOMACHINE
The double-skin annular envelope and adjustable diaphragm in the combustion gas exhaust nozzle address temperature protection and gas reintroduction issues, improving thermal insulation and reducing maintenance needs in aircraft turbomachines.
Patent Information
- Application Number
- FR2021012936
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2021-12-03
- Publication Date
- 2025-04-18
- Estimated Expiration
- 2041-12-03
AI Technical Summary
Current combustion gas exhaust nozzles for aircraft turbomachines face issues with inadequate protection of the annular housing from high temperatures and the risk of combustion gas reintroduction into ventilation channels, leading to increased maintenance needs and potential disruption of ventilation.
The nozzle features a double-skin annular envelope with internal and external skins linked by bonding elements, creating two ventilation air passage channels to enhance thermal protection and a mechanical diaphragm for adjustable air outlet section to prevent gas reintroduction.
The double-skin design improves thermal insulation and reduces maintenance requirements, while the adjustable diaphragm ensures effective ventilation air outlet control, minimizing the risk of gas reintroduction and enhancing the nozzle's lifespan.
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Abstract
Description
Title of the invention: COMBUSTION GAS EXHAUST NOZZLE FOR AN AIRCRAFT TURBOMACHINE Technical field of the invention
[0001] The present invention relates to a combustion gas exhaust nozzle for an aircraft turbomachine, as well as to an aircraft turbomachine comprising such a nozzle. Technical background
[0002] An aircraft turbomachine conventionally comprises a gas generator comprising from upstream to downstream at least one compressor, an annular combustion chamber and at least one turbine. The expressions upstream and downstream refer to the flow of gases in the turbomachine, the gases starting by being compressed in the compressor(s), being mixed with fuel and burned in the combustion chamber, then being expanded in the turbine(s).
[0003] Downstream of the turbine(s), the turbomachine comprises a nozzle for exhausting or ejecting the combustion gases. In the context of the present invention and with reference to [Fig. 1], the nozzle 10 comprises:
[0004] - an ejection cone 12 which is centered on an axis and whose external diameter decreases along the axis from its upstream end (left on the drawing) to its downstream end (right on the drawing),
[0005] - an annular casing 14 which extends around the axis and the cone 12 and which carries at its downstream end of the 16 pivoting flaps, and
[0006] - an annular envelope 18 which extends around the axis and inside the casing annular 14, this envelope 18 delimiting with the cone 12 an annular vein 20 for the flow of combustion gas (arrow F1) along the axis and with the casing 14 an annular channel 22 for the passage of ventilation air (arrow F2) along the axis.
[0007] This type of nozzle 10 is for example used in a gas generator equipped with a post-combustion system. This system is mounted downstream of the combustion chamber and makes it possible to generate additional combustion of the gases by injecting more fuel.
[0008] The combustion gases can reach very high temperatures and this is even more true for the combustion gases leaving the post-combustion system.
[0009] In the aforementioned nozzle 10, the annular casing 12 is generally made of a metal alloy, for example based on titanium, which has relatively limited thermal resistance and which is protected from combustion gases by the casing 18 and by the ventilation air passage channel 22 defined between the casing 18 and the casing 14. The casing has a thermal resistance of around 350°C and the combustion gases can reach 800°C in the vein 20. The temperature difference is therefore significant, hence the importance of protecting the casing 14 by the casing 18 and the channel 22.
[0010] In current technology, the casing 18 is formed by a corrugated sheet metal better visible in [Fig. 2]. However, this sheet metal does not always effectively protect the casing 14. It is therefore necessary to regularly carry out operations to check and replace the parts of the nozzle 10, in particular after a post-combustion phase.
[0011] Furthermore, another sheet 24 is mounted at the downstream end of the channel 22 and is fixed to the casing 14. This sheet 24 has a generally frustoconical shape and delimits with the casing 18 passages for the outlet of air from the channel 22. However, in operation, there is a risk of reintroduction of combustion gases from the vein 20 into the channel 22 via these passages (arrow F3). These combustion gases are likely to disturb the ventilation of the casing 14 and increase the temperature of the latter, which is problematic.
[0012] The present invention aims to remedy at least some of the problems mentioned above. Summary of the invention
[0013] According to a first aspect, the invention relates to a combustion gas exhaust nozzle for an aircraft turbomachine, this nozzle comprising:
[0014] - an ejection cone which is centered on an axis and whose external diameter decreases the along the axis from its upstream end to its downstream end,
[0015] - an annular casing which extends around the axis and the cone and which carries at its downstream end of the pivoting flaps, and
[0016] - an annular envelope which extends around the axis and inside the casing annular, this envelope delimiting with the cone an annular vein of combustion gas flow along the axis and with the casing a first annular channel for ventilation air passage along the axis,
[0017] characterized in that the envelope is of the double-skin type and comprises two annular skins, respectively internal and external, which are radially spaced from each other and are connected to each other by connecting elements, these skins defining between them a second annular channel for the passage of ventilation air along the axis.
[0018] The invention makes it possible to protect the casing of the nozzle from the high temperatures which prevail during operation inside the casing. Two annular ventilation air passage channels protect the casing. The first channel is provided between the casing and the housing and a second channel is provided inside the casing. This makes it possible to improve the thermal resistance of the nozzle and its service life, and to limit the needs of operation of control and maintenance of the nozzle in particular after post-combustion although the invention is not limited to this type of application.
[0019] The nozzle according to the invention may comprise one or more of the following characteristics, taken in isolation from one another, or in combination with one another:
[0020] - the casing is made of metal alloy and forms a single-piece unit obtained by mechanical welding,
[0021] - the connecting elements are attached and fixed to the internal skin or are integrated into the internal skin, and the external skin is attached and fixed to the connecting elements, - the outer skin includes holes which open at the level of the connecting elements to allow the outer skin to be fixed by welding to the connecting elements, - the connecting elements have an elongated shape and a cross-section substantially in the shape of a U, I, T or Q, - the connecting elements extend around the axis in a circular or helical manner, - the connecting elements are spaced apart from each other and define air passages between them, and / or have axially oriented orifices for the passage of ventilation air, - the casing is fixed in a cantilevered manner to the casing by its upstream end, - the inner skin comprises at an upstream end an annular flange which extends radially outwards and which is fixed to an annular flange of the casing, the flange of the inner skin comprising an annular row of air supply orifices for said first and second channels, - the outer skin comprises a truncated upstream end which is flared upstream and which is separated by clearances from the casing and the flange of the inner skin, - the casing comprises at a downstream end an annular row of lugs which extend in a radial direction and each comprise a radially internal end fixed to the casing and a radially external end bearing radially against the casing or a member carried by the casing, - the legs each have a general S shape, - the legs are fixed by welding to the connecting elements,
[0022] — the second channel has a thickness in the radial direction of between 2 and 10 mm, and preferably between 3 and 8mm.
[0023] According to a second aspect, the invention relates to a combustion gas exhaust nozzle for an aircraft turbomachine, this nozzle comprising:
[0024] - an ejection cone which is centered on an axis and whose external diameter decreases the along the axis from its upstream end to its downstream end,
[0025] - an annular casing which extends around the axis and the cone and which carries at its downstream end of the pivoting flaps, and
[0026] - an annular envelope which extends around the axis and inside the casing annular, this envelope delimiting with the cone an annular vein of combustion gas flow along the axis and with the casing an annular channel for ventilation air passage along the axis,
[0027] characterized in that it further comprises a mechanical diaphragm which is mounted at the downstream end of the channel and which is configured to allow adjustment of an air outlet section of this channel.
[0028] The invention makes it possible to adjust the air outlet section of the ventilation air passage channel. This adjustment can be temporary or permanent and is defined so as to guarantee the outlet of the ventilation air while avoiding or limiting the risk of reintroduction of vein gas into the channel. The outlet section can thus be adjusted and maintained throughout the operating time or even the entire service life of the turbomachine. The outlet section can also be adjusted directly as a function of the speed or the operating phase of the turbomachine.
[0029] The nozzle according to the invention may comprise one or more of the following characteristics, taken in isolation from one another, or in combination with one another:
[0030] - the diaphragm comprises two annular parts, respectively internal and external, the external part being fixed and carried by the casing, and the internal part being mounted to be mobile in rotation relative to the external part, the rotational movement of the internal part relative to the external part making it possible to adjust the air outlet section of the channel,
[0031] - the parts are fixed in a cantilevered manner to the casing, - each of the external and internal parts has an L-shaped section and comprises a cylindrical or truncated cone-shaped wall which is connected at its downstream end to an inwardly oriented radial rim, - the radial rim of the outer part comprises an annular row of first axial orifices, and the radial rim of the inner part comprises an annular row of second axial orifices, - the first and second orifices have the same shape chosen from circular, elongated, elliptical, oblong, square and rectangular shapes, - the radial rim of the outer part comprises an annular row of third axial orifices, and the radial rim of the inner part comprises an annular row of fourth axial orifices, the inner part being movable relative to the external part from a first extreme position in which the first orifices are aligned with the second orifices and the third orifices communicate with the fourth orifices, to a second opposite extreme position in which the first and second orifices are closed and the third orifices communicate with the fourth orifices, - at least one of the radial edges comprises inward radial extensions on which the casing is capable of coming into radial support, these radial extensions defining ventilation air passages between them. - the external part has its upstream end which is applied radially against the casing and fixed to this casing, and the rest of the external part is radially spaced from the casing, - the internal part comprises at its upstream end radial studs which project outwards and are received in radial housings of the external part, each of these radial studs having a circumferential dimension smaller than that of the housing in which it is received so as to be able to circumferentially move the studs in the housings and therefore the internal part with respect to the external part, - each of the studs is applied radially against the casing and comprises a threaded radial orifice which is aligned with an orifice in the casing which has an elongated shape in the circumferential direction, a screw being screwed from the outside into the threaded orifice of each of the studs and passing through the orifice in the casing, - the nozzle further comprises at least one actuator for moving the internal part relative to the external part, - the upstream ends of the parts are separated from each other by a radial clearance for the passage of air, and the external part comprises through holes for the passage of this air,
[0032] — the angular movement of the internal part with respect to the external part of the diaphragm is less than 20°, and preferably between 5 and 10°,
[0033] — the number of first orifices is equal to the number of third orifices and is between 50 and 1000, preferably between 60 and 720.
[0034] The invention also relates to an aircraft turbomachine comprising a nozzle as described above. Brief description of the figures
[0035] Other characteristics and advantages will emerge from the following description of a non-limiting embodiment of the invention with reference to the appended drawings in which:
[0036] [Fig.l] [Fig.l] is a partial schematic view in axial section of an exhaust nozzle of an aircraft turbomachine,
[0037] [Fig.2] [Fig.2] is a partial schematic perspective view of an envelope of the nozzle of [Fig.l],
[0038] [Fig.3] [Fig.3] is a partial schematic view in axial section of a mode of rea construction of an exhaust nozzle of an aircraft turbomachine,
[0039] [Fig.4] [Fig.4] is an enlarged view of a detail of [Fig.3] and illustrates ventilation air circulation,
[0040] [Fig.5] [Fig.5] is an enlarged view of another detail of [Fig.3] and illustrates ventilation air circulation,
[0041] [Fig.6] [Fig.6] is a schematic perspective view of the nozzle casing of [Fig.3],
[0042] [Fig.7] [Fig.7] is a schematic perspective and axial sectional view of the casing of the nozzle of [Fig.3],
[0043] [Fig.8] [Fig.8] is another schematic perspective view of the envelope of the nozzle of [Fig.3],
[0044] [Fig.9] [Fig.9] is a schematic perspective view of a variant of the rea lization of the envelope and shows the internal wall and connecting elements of this envelope,
[0045] [Fig. 10] [Fig. 10] is a schematic perspective view of another alternative embodiment of the envelope and shows the internal wall and connecting elements of this envelope,
[0046] [Fig. 11] [Fig. 11] is a schematic perspective view of another alternative embodiment of the envelope and shows the internal wall and connecting elements of this envelope,
[0047] [Fig. 12] [Fig. 12] is a schematic perspective and axial sectional view of another detail of [Fig.3] and shows a mechanical diaphragm,
[0048] [Fig. 13] [Fig. 13] is another schematic perspective and axial sectional view of the mechanical diaphragm,
[0049] [Fig. 14] [Fig. 14] is a partial schematic perspective view of an internal portion of the diaphragm of [Fig. 12],
[0050] [Fig. 15] [Fig. 15] is a partial schematic perspective view of an external portion of the diaphragm of [Fig. 12],
[0051] [Fig. 16] [Fig. 16] is a partial schematic perspective view of the inner and outer portions of the diaphragm of [Fig. 12], and illustrates an extreme position of the inner portion relative to the outer portion, and
[0052] [Fig.l7a-17c] Figures 17a to 17c illustrate alternative embodiments of the mechanical diaphragm. Detailed description of the invention
[0053] Figures 1 and 2 have been described in the above.
[0054] [Fig. 3] illustrates an embodiment of an exhaust nozzle 10 according to the invention. This nozzle 10 incorporates two aspects of the invention which can be used independently of each other or in combination.
[0055] The nozzle 10 comprises:
[0056] - an ejection cone 12 which is centered on an axis X and whose external diameter decreases along the X axis from its upstream end (left in the drawing) to its downstream end (right in the drawing),
[0057] - an annular casing 14 which extends around the axis and the cone 12 and which carries at its downstream end of the 16 pivoting flaps, and
[0058] - an annular envelope 18 which extends around the axis X and inside the casing annular 14, this envelope 18 delimiting with the cone 12 an annular vein 20 for the flow of combustion gas (arrow F1) along the axis and with the casing 14 an annular channel 22 for the passage of ventilation air (arrow F2) along the axis.
[0059] In the example shown, the cone 12 comprises an upstream section 12a which is generally cylindrical and a downstream section 12b which is generally frustoconical and whose diameter decreases from upstream to downstream. This cone 12 is fixed and carried by an element of the turbomachine which is located upstream and is not visible in the drawing.
[0060] The casing 14 has a generally frustoconical shape in the example shown, the external diameter of which decreases from upstream to downstream. At its upstream end, the casing 14 comprises a radially external annular flange 14a. This flange 14a is part of a part 14b of the casing 14, which has a relatively large thickness compared to the rest of the casing 14 and which is added and fixed, for example by welding, to the downstream end of a wall 14c of the casing 14.
[0061] The flaps 16 are distributed around the axis X. Each flap 16 is pivotally mounted by its upstream end around an axis 26 tangent to a circumference centered on the axis X. Each flap 16 is movable from a first position shown in [Fig. 3] in which it extends substantially in the extension of the casing 14, to a second position in which its downstream end is brought closer to the axis X and the cone 12. When the flaps 16 are in this second position, the passage section at the outlet of the vein 20 is reduced, which accelerates the combustion gases.
[0062] [Fig. 3] shows that the pivot axes 26 of the flaps 16 are carried by a device 28 which comprises force-recovery arms 30. These arms 30 comprise upstream hooks 32 which are engaged with an internal annular rib 34 of the aforementioned part 14b of the casing 14.
[0063] The envelope 18 is here double-skinned and comprises two annular skins, respec internal 18a and external 18b, which are radially spaced from each other and are connected to each other by connecting elements 36.
[0064] The skins 18a, 18b define between them a second annular channel 38 for the passage of ventilation air along the axis X (arrow F4).
[0065] Figures 4 and 5 show respectively the upstream and downstream axial ends of the casing 18 and the circulation of the ventilation air in the two channels 22, 38.
[0066] The casing 18 is preferably made of a metal alloy and preferably forms a single-piece assembly obtained by mechanical welding.
[0067] Furthermore, the casing 18 is preferably fixed in a cantilevered manner to the casing 14 by its upstream end.
[0068] For this, the casing 18 comprises at its upstream end an annular flange 40 which extends radially outwards and which is fixed to the flange 14a of the casing 14, and more precisely which is clamped axially between a flange 42 of an element of the turbomachine located upstream of the nozzle 10 and the flange 14a of the casing 14.
[0069] In the example shown, the flange 40 is connected to the upstream end of the inner skin 18a. This flange 40 comprises an annular row of orifices 44 for supplying air to the channels 22, 38, as seen in [Fig. 4] (arrow F5). The orifices 44 are oriented axially.
[0070] Preferably, the connecting elements 36 are attached and fixed to the internal skin 18a or are integrated into the internal skin 18, and the external skin 18b is attached and fixed to the connecting elements 36.
[0071] In addition to their connecting function, the elements 36 may have an additional function of stiffening the envelope.
[0072] Figures 3 to 8 illustrate a first embodiment of the casing 18 in which the connecting elements 36 have a generally elongated shape and are oriented in a helical manner around the axis X ([Fig.6]). The connecting elements 36 have a generally U-shaped or Q-shaped cross-section (Figures 7 and 8). They are made of a weldable material similar to that of the skins 18a, 18b and are fixed to the internal skin 18a at their radially internal ends.
[0073] The outer skin 18b is attached to the projecting elements 36 and fixed thereto. For this purpose, the outer skin 18b may comprise through orifices 46 which are located at the level of the projecting elements 36 ([Fig.6]). These orifices 46 make it possible to produce welding points or beads between the skin 18b and the projecting elements 36.
[0074] [Fig. 6] shows that the connecting elements 36 are circumferentially spaced from each other and define between them air passages in the channel 38. Insofar as the connecting elements 36 here have a U shape and are not blocked at their ends, they themselves form air passages in the channel 38 with the inner skin 18a to which they are connected.
[0075] [Fig. 3] shows that the upstream ends of the connecting elements 36 are axially spaced from the flange 40. The upstream end of the outer skin 18b is also axially spaced from the flange 40 and axially and / or radially spaced from the casing 14. The upstream end of the outer skin 18b here has a frustoconical shape that flares out towards the upstream end and is thus separated by clearances from the casing 14 and the flange 40 of the inner skin 18a.
[0076] [Fig.4] shows that the downstream end of the inner skin 18a extends further downstream than the outer skin 18b.
[0077] [Fig. 5] also shows that the casing 18 comprises at its downstream end an annular row of tabs 48 which extend in a radial direction and each comprise a radially internal end 48a fixed to the casing 18 and a radially external end 48b bearing radially against the casing 14 or a member carried by the casing 14 (Figures 5 and 8). This member is here a diaphragm 50 which will be described in more detail in the following. The downstream end of the internal skin 18a is also bearing radially outwards on the diaphragm 50.
[0078] The legs 48 each have a general S shape. Their radially internal ends 48a are here fixed by welding to the downstream ends of the connecting elements 36 ([Fig.8]).
[0079] The channel 22 has, for example, a thickness in the radial direction of between 2 and 10 mm, and preferably between 3 and 8 mm.
[0080] Figures 4 and 5 show that a portion of the air exiting the orifices 44 of the flange 40 of the inner skin enters the channel 38 of the casing 18, being guided at the inlet by the frustoconical end of the outer skin 18b (arrow F2). This air circulates in the channel 38, between the connecting elements 36 and in the connecting elements, and reaches the downstream end of the casing 18 where it is discharged through the diaphragm 50 or between the diaphragm 50 and the downstream end of the inner skin 18a, as will be described below.
[0081] The other part of the air leaving the orifices 44 bypasses the upstream end of the external skin 18b and enters the channel 22 to circulate to the diaphragm where it can in particular be evacuated through the diaphragm 50 or between the diaphragm 50 and the downstream end of the internal skin 18a.
[0082] [Fig. 9] illustrates an alternative embodiment of the casing 18 whose external wall 18b has not been shown for clarity. The connecting elements 36 here have a generally elongated shape in the circumferential direction. They thus extend around the axis in a circular manner. They are distributed in three rows, respectively upstream 36a, intermediate 36b and downstream 36c. The circumferential dimensions of the connecting elements 36 of the upstream row 36a are larger than those of the connecting elements 36 of the intermediate row 36b, which are larger than those of the connecting elements 36 of the downstream row 36c. In each row, the connecting elements 36 are spaced apart in the circumferential direction from each other to allow the passage of air in the channel 38. Each of the connecting elements 36 has a substantially Q-shaped cross-section.
[0083] [Fig. 10] illustrates another alternative embodiment of the casing 18, the external wall 18b of which has not been shown for clarity. The connecting elements 36 here have a generally elongated shape and are oriented in a helical manner around the axis X, like the first embodiment. The connecting elements 36 are spaced apart in the circumferential direction from each other to allow the passage of air in the channel 38. Each of the connecting elements 36 has a substantially louT cross-section.
[0084] [Fig. 11] illustrates another alternative embodiment of the casing 18, the external wall 18b of which has not been shown for clarity. The connecting elements 36 have an annular shape and extend continuously around the axis X. There are three of them, respectively upstream 36a, intermediate 36b and downstream 36c. The connecting elements 36 comprise axially oriented orifices 52 for the passage of ventilation air. Each of the connecting elements 36 has a substantially I- or T-shaped cross-section.
[0085] We now refer to Figures 12 to 16 which illustrate an embodiment of the diaphragm 50 visible in its environment in Figures 3 and 5.
[0086] The diaphragm 50 is a mechanical diaphragm, that is to say that it comprises mechanical parts which cooperate with each other by relative displacement. In the context of the nozzle 10 according to the invention, the diaphragm 50 is mounted at the downstream end of the channel 22 and is configured to allow adjustment of the air outlet section of this channel 22.
[0087] The diaphragm 50 comprises two annular parts, respectively internal 54 and external 56. The external part 56 is fixed and carried by the casing 14. The internal part 54 is mounted to move in rotation inside the external part 56. The rotational movement of the internal part 54 relative to the external part 56 makes it possible to adjust the air outlet section of the channel 22.
[0088] In the example shown, the parts 54, 56 are fixed in a cantilevered manner to the casing 14 by means of their upstream ends.
[0089] Each of the parts 54, 56 has an L-shaped section and comprises a cylindrical wall 54a, 56a or frustoconical wall which is connected at its downstream end to an inwardly oriented radial rim 54b, 56b.
[0090] The wall 56a of the external part 56 extends substantially parallel to the casing 14, inside the latter, and comprises at its upstream end an annular excess thickness forming a fixing flange 58. This flange 58 has a generally cylindrical shape and comprises at its upstream end radial notches 60 which have a circumferential width or dimension L1.
[0091] The wall 56a of the external part 56 is fixed to the casing 14 by its upstream end and in particular by its flange 58 which is in radial support against a cylindrical face of the casing 14. For this, the flange 58 can comprise threaded orifices which open radially towards the outside and are aligned with orifices of the casing 14. Screws (not shown) pass through these orifices of the casing 14 and are screwed into the threaded orifices of the flange 58 to fix the external part 56 to the casing 14.
[0092] The remainder of the wall 56a is radially spaced from the casing 14 and defines with it an annular space 62 for circulation of ventilation air coming from the channel 22. For this, the wall 56a comprises at least one annular row of holes 64 passing through in the radial direction.
[0093] The radial rim 56b of the external part 56 comprises an annular row of axial orifices 66 and an annular row of axial orifices 68. In the example shown in the drawings and in particular in FIGS. 14 to 16, the orifices 66 have a generally elongated shape in the radial direction. The orifices 68 have a generally elongated shape in the circumferential direction and are fewer in number than the orifices 66. The passage section of one of the orifices 66 is denoted SI and the cumulative passage section of the orifices is denoted SI'. The passage section of one of the orifices 68 is denoted S2 and the cumulative passage section of the orifices is denoted S2'. The sections SI, SI', S2 and S2' do not appear in the drawings.
[0094] The radial rim 56b of the external part 56 further comprises inward radial extensions 70 on which the envelope 18, and in particular its downstream end or the downstream end of its internal skin 18a, is capable of coming into radial support, as mentioned above. These radial extensions 70 define between them passages 72 for ventilation air exiting from the channel 22 and / or from the channel 38 ([Fig.16]).
[0095] The wall 54a of the inner part 54 extends substantially parallel to the wall 56a of the outer part 56, inside the latter, and comprises at its upstream end an annular excess thickness forming a fixing flange 74. This flange 74 has a generally cylindrical shape and carries radial studs 76 which extend radially outwards and are housed in the notches 60 of the wall 56a. Each of the studs 76 has a circumferential width or dimension L2 which is less than L1 so that the studs 76 can move in the circumferential direction in the notches 60, and therefore the inner part 54 can move circumferentially relative to the outer part 56.
[0096] The wall 54a of the internal part 54 is fixed to the casing 14 by its upstream end and in particular by its flange 74 and its studs 76 which are in radial support against the face cy aforementioned lindic of the casing 14. These studs 76 comprise tapped orifices 78 (figures 14 and 16) which open radially outwards and are aligned with orifices (not visible) of the casing 14. The orifices of the casing 14 are oriented radially and have a generally elongated shape in the circumferential direction. A screw 80 is engaged in each orifice of the casing and screwed into the threaded orifice 78 of each stud 76 so as to be able to radially tighten the internal part 54 against the casing 14. The circumferentially elongated shape of the orifices of the casing 14 allows the screw 80 to be mounted and tightened regardless of the angular position of the internal part 54 inside the external part 56. It is therefore understood that the displacement travel of each stud 76 in its notch 60 corresponds to the displacement travel of the screw 80 in the orifice of the casing 14.
[0097] The displacement path of each stud 76 in a notch 60 and therefore of the internal part 54 with respect to the external part 56 of the diaphragm 50 represents an angular movement of less than 20° preferably, and for example between 5 and 10°, around the axis X.
[0098] The remainder of the wall 54a is radially spaced from the wall 56a and defines with it an annular space 82 for circulation of ventilation air coming from the channel 22. Figures 12 and 13 show that the flanges 58, 74 are separated from each other by a radial clearance J which allows ventilation air coming from the channel 22 to penetrate into this space 82. This air is then evacuated into the space 62 through the holes 64.
[0099] The radial rim 54b of the internal part 54 comprises an annular row of axial orifices 84 and an annular row of axial orifices 86. In the example shown in the drawings and in particular in FIGS. 14 to 16, the orifices 84 have a generally elongated shape in the radial direction, which is identical to that of the orifices 66. The orifices 86 have a generally circular shape and are fewer in number than the orifices 84. The number of orifices 84 is equal to the number of orifices 66, and is for example between 50 and 1000, preferably between 60 and 720. The number of orifices 86 is equal to the name of the orifices 68. The passage section of one of the orifices 84 is noted SI and is therefore identical to the passage section of the orifices 66. The cumulative passage section of the orifices 84 is noted SI'. The passage section of one of the orifices 86 is noted S3 and is less than the passage section S2. The cumulative passage section of the orifices is noted S3'.Sections S3, S3' do not appear in the drawings.
[0100] The internal part 54 is movable relative to the external part 56 from a first extreme position visible in [Fig. 16] in which the orifices 84 and 66 are aligned and the orifices 86 and 68 communicate with each other, to a second opposite extreme position (not shown) in which the orifices 84 of the rim 54b are closed by the rim 56b (and more precisely by the solid parts of the rim 56b located between the orifices 66), the orifices 66 of the rim 56b are closed by the rim 54b (and more exactly by the solid parts of the rim 54b located between the orifices 84), and the orifices 86 and 68 always communicate with each other. Whatever the circumferential position of the internal part 54 with respect to the external part 56, the orifices 86 and 68 therefore communicate with each other. This is made possible in particular by the fact that the displacement stroke of each orifice 86 with respect to the orifice 68 corresponds to the displacement stroke of the stud 76 in its notch 60.
[0101] As can be seen in Figures 17a to 17c, the orifices 66, 68, 84, 86 can have any shape and any dimensions. Their numbers are adapted according to their shapes and dimensions. The orifices 66, 68, 84, 86 can thus have a shape chosen from circular, elongated, elliptical, oblong, square, rectangular, etc.
[0102] In operation, it is understood that a first part of the ventilation air which circulates in the channel 22 will enter the space 82 and will then circulate through the holes 64 into the space 62 to then be discharged downstream of the nozzle 10, between the downstream end of the casing 14 and the downstream end of the diaphragm 50. A second part of the ventilation air which circulates in the channel 22, which can mix with a part of the air leaving the channel 38, will pass through the orifices 68, 86, or even also the orifices 66, 84 depending on the position of the diaphragm 50, and is also expelled downstream of the nozzle 10. Finally, a third part of the ventilation air which circulates in the channel 22 can mix with a part of the air leaving the channel 38 and pass through the passages 72 to be expelled downstream of nozzle 10.
[0103] The adjustment of the diaphragm 50 can be carried out by an operator during the manufacture or assembly of the nozzle 10 according to pre-established criteria. The diaphragm 50 would then no longer be intended to be modified except during a maintenance operation for example.
[0104] Alternatively, the nozzle 10 could be equipped with an actuator 90 which would be used to ensure the movement of the internal part 54 with respect to the external part 56 ([Fig. 16]). This actuator 90 could be carried by the casing 14 and mechanically connected to the internal part 54. The screws 80 could then no longer be used to radially tighten the internal part 54 but to retain it radially with respect to the casing 14.
Claims
Claims
1. Combustion gas exhaust nozzle (10) for an aircraft turbomachine, this nozzle (10) comprising: - an ejection cone (12) which is centered on an axis (X) and whose external diameter decreases along the axis from its upstream end to its downstream end, - an annular casing (14) which extends around the axis (X) and the cone (12) and which carries at its downstream end pivoting flaps (16), and - an annular casing (18) which extends around the axis (X) and inside the annular casing (14), this casing (18) delimiting with the cone (12) an annular flow path (20) of combustion gas along the axis (X) and with the casing (14) a first annular channel (22) for the passage of ventilation air along the axis (X), characterized in that the envelope (18) is of the double-skin type and comprises two annular skins, respectively internal (18a) and external (18b),which are radially spaced from each other and are connected to each other by connecting elements (36), these skins (18a, 18b) defining between them a second annular channel (38) for the passage of ventilation air along the axis (X).,
2. Nozzle (10) according to claim 1, in which the casing (18) is made of a metal alloy and forms a single-piece assembly obtained by mechanical welding.
3. Nozzle (10) according to claim 1 or 2, in which the connecting elements (36) are attached and fixed to the inner skin (18a) or are integrated into the inner skin (18a), and the outer skin (18b) is attached and fixed to the connecting elements (36).
4. Nozzle (10) according to all of claims 2 and 3, in which the outer skin (18b) comprises orifices (46) which open at the level of the connecting elements (36) to allow the outer skin (18b) to be fixed by welding to the connecting elements.
5. Nozzle (10) according to one of the preceding claims, in which the connecting elements (36) have an elongated shape and a substantially U, I, T or Q cross-section.
6. Nozzle (10) according to one of the preceding claims, in which the connecting elements (36) extend around the axis (X) in a circular or helical manner.
7. Nozzle (10) according to one of the preceding claims, in which the connecting elements (36) are spaced apart from each other and define air passages between them, and / or comprise axially oriented orifices (52) for the passage of ventilation air.
8. Nozzle (10) according to one of the preceding claims, in which the casing (18) is fixed in a cantilevered manner to the casing (14) by its upstream end.
9. Nozzle (10) according to one of the preceding claims, in which the inner skin (18a) comprises at an upstream end an annular flange (40) which extends radially outwards and which is fixed to an annular flange (14a) of the casing (14), the flange (40) of the inner skin (18a) comprising an annular row of orifices (44) for supplying air to said first and second channels (22, 38).
10. Nozzle (10) according to claim 9, in which the outer skin (18b) comprises a frustoconical upstream end which is flared upstream and which is separated by clearances from the casing (14) and the flange (40) of the inner skin (18a).
11. Nozzle (10) according to one of the preceding claims, in which the casing (18) comprises at a downstream end an annular row of tabs (48) which extend in the radial direction and each comprise a radially internal end (48a) fixed to the casing (18) and a radially external end (48b) bearing radially against the casing (14) or a member carried by the casing (14).
12. A nozzle (10) according to claim 11, wherein the legs (48) each have a general S shape.
13. A nozzle (10) according to claim 11 or 12, wherein the tabs (48) are fixed by welding to the connecting elements (36).
14. Aircraft turbomachine, comprising a nozzle (10) according to one of the preceding claims.