ARRANGEMENT FOR A TURBOMACH

Description

Technical field of the invention

[0001] The invention relates to an assembly for a turbomachine, in particular an ejection assembly for an aircraft turbojet or turboprop. State of the prior art

[0002] A propulsion system for an aircraft, also called an integrated propulsion system, typically comprises a turbomachine, for example a turbojet, a nacelle and a mast or attachment pylon intended to allow the propulsion system to be attached to a structural part, for example under the wing, of the aircraft.

[0003] The turbomachine is for example a double-flow turbojet. Such a turbomachine 1, illustrated in figure 1 , has an X axis and comprises from upstream to downstream in the direction of circulation of the gases within the turbomachine, a fan 2, a low pressure compressor 3, a high pressure compressor 4, a combustion chamber 5, a high pressure turbine 6 and a low pressure turbine 7.

[0004] In the following description, the terms upstream and downstream are defined in relation to the direction of gas flow within the turbomachine.

[0005] Furthermore, the terms axial, radial and circumferential are defined relative to the X axis of the turbomachine.

[0006] The air F entering the blower is divided into a primary air flow F1 circulating through a so-called primary vein 8 and into a secondary air flow F2 circulating through a so-called secondary vein 9, surrounding the primary vein 8. The low and high pressure compressors 3, 4, the combustion chamber 5 and the high and low pressure turbines 6, 7 are located at the level of the primary vein 8.

[0007] The high-pressure turbine 6 drives the high-pressure compressor 4 via a so-called high-pressure shaft. The low-pressure turbine 7 drives the low-pressure compressor 3 and the blower 2, via a so-called low-pressure shaft and possibly via a speed reducer in the case where the rotational speed of the blower 2 is lower than the rotational speed of the low-pressure compressor 3.

[0008] Most of the thrust generated by turbomachine 1 is produced by the secondary flow F2, downstream of fan 2.

[0009] The fan 2 is surrounded by a fan casing 10, a so-called intermediate casing 11 being located downstream of the fan casing 10. The intermediate casing 11 comprises a radially external shell 12 located in the extension of the fan casing 10 and a so-called inter-stream part 13, located between the primary 8 and secondary 9 streams. The inter-stream part 13 comprises a separating nozzle 14 at its upstream end and is connected to the external shell 12 by so-called structural arms 15.

[0010] The turbomachine 1 also comprises a central casing 16, located downstream of the inter-stream part 13 of the intermediate casing 11, and an exhaust casing 17, located downstream of the central casing 16 and on which an ejection cone 18 is attached. As can be better seen in the figure 2 , the exhaust casing 17 comprises a radially inner ferrule 19 and a radially outer ferrule 20, connected by radially extending blades. The inner ferrules 19 and outer ferrules 20 of the exhaust casing 17 or engine casing delimit between them the downstream end of the primary vein 8.

[0011] As illustrated in the figure 2 , the nacelle 21 of the propulsion unit conventionally comprises a fan nacelle 22, surrounding the fan 2 as well as the fan casing 10 and the external shroud 12 of the intermediate casing 11. The fan nacelle 22 forms an air inlet lip 23 at its upstream end. The nacelle 21 further comprises an engine nacelle 24 surrounding the zones of the turbomachine 1 comprising the high-pressure compressor 4, the combustion chamber 5, the high-pressure turbine 6, and the low-pressure turbine 7 in particular.

[0012] As illustrated in the figure 3 and is known from document FR 3 084 916 in the name of the Applicant, the upstream end of the ejection cone 18 is connected to the downstream end of the internal shell 19 of the exhaust casing 17 by means of an annular connecting flange 25 (also visible in the figure 4 ). The cone 18 is generally made of ceramic matrix composite material, also referred to by the English acronym CMC. The cone 18 may also include an internal acoustic structure 26. The internal shell 19 of the exhaust casing 18 is metallic, for example made of a nickel-based alloy, for example Inconel.

[0013] The flange 25 is metallic, for example made of a nickel-based alloy (Inconel for example), and comprises an annular part 27 of axis X, from which flexible tabs 28 extend. The tabs 28 are regularly distributed around the circumference.

[0014] Such flexible or supple tabs 28 make it possible to compensate for the differential expansion phenomena occurring between the internal shell 19 of the exhaust casing 17 and the cone 18, these two elements 17, 18 being made of different materials.

[0015] Such an annular flange 25 is generally manufactured by machining a large raw element, such manufacturing being relatively expensive. Presentation of the invention

[0016] The invention aims to remedy this drawback in a simple, reliable and inexpensive manner.

[0017] To this end, the invention relates to an assembly for a turbomachine comprising an ejection cone and an exhaust casing comprising an annular inner shell, the ejection cone and the exhaust casing extending around an axis, the ejection cone comprising an outer surface extending in the extension of said inner shell, the ejection cone being connected to the exhaust casing by means of a flange, said flange comprising an upstream part fixed to the exhaust casing and lugs extending downstream from said upstream part, the ejection cone being fixed to said lugs, characterized in that the flange is sectorized and is formed of several angular sectors arranged circumferentially adjacently, each flange sector comprising at least one lug extending rectilinearly along an axis parallel to the axis of the cone.

[0018] It is thus possible to produce each flange sector using a raw material element of smaller dimensions than in the case of the prior art, which makes it possible to limit costs and machining times. Such a structure also allows the implementation of mass production of the flange sectors.

[0019] The fact that each leg is flat and extends along a rectilinear axis parallel to the axis of the exhaust casing and the cone, i.e. parallel to the axis of the turbomachine, makes it possible to limit the mechanical stresses in each flange sector, and in particular in the legs, so as to avoid any premature degradation. Such a structure of the legs also makes it easier to produce the sectors and to limit the size of each sector.

[0020] The legs may be formed by blades, for example flat. Each leg may have a substantially constant thickness. Each leg may have a generally rectangular shape, seen radially from the outside to the inside. Each leg may have a rectangular section.

[0021] Adjacent sectors may be arranged end to end or may be regularly spaced apart from each other in the circumferential direction.

[0022] Each lug may be flexible or elastically deformable in the radial direction, so as to compensate for possible differential expansion effects between the cone and the exhaust casing, when these are made of different materials for example. The thickness of each lug, that is to say its dimension in the radial direction, is for example between 0.5 mm and 10 mm.

[0023] The cone is, for example, made, at least in part, of ceramic matrix composite material, also known by the English acronym CMC. The exhaust casing is, for example, made, at least in part, of metallic material capable of withstanding high temperatures during operation of the turbomachine.

[0024] Each flange sector can extend over an angular range of less than 180°.

[0025] The number of sectors distributed around the circumference can thus be between 0 and 200. Each flange sector can have between 1 and 100 legs, preferably between 1 and 10 legs, preferably between 3 and 6 legs.

[0026] The assembly may include means for coupling in rotation and / or positioning each flange sector.

[0027] The rotational coupling and / or positioning means may comprise at least one positioning stud formed on the corresponding sector, engaged in a recess or a complementary orifice of the exhaust casing or the cone, or vice versa.

[0028] The positioning stud may extend radially from the upstream portion of each sector and be engaged in a complementary shaped recess or orifice in the exhaust casing. Of course, the recess or orifice may be provided in an element fixed to the exhaust casing or to the cone.

[0029] The rotational coupling and / or positioning means may comprise at least one flat formed on the corresponding sector, bearing on a corresponding edge or flat surface of the exhaust casing or the cone, or vice versa.

[0030] Of course, the flat part can rest on an edge or a corresponding flat surface of an element fixed to the exhaust casing or to the cone.

[0031] The rotational coupling means are capable of preventing rotation of the corresponding sector relative to an axis perpendicular to the axis of the cone and the exhaust casing, i.e. relative to a radial axis.

[0032] The flat may be formed by a projecting area extending from the upstream portion of the corresponding sector and may bear on an edge or a corresponding flat area of ​​the exhaust casing or of an element fixed to said exhaust casing.

[0033] For each sector, the rotational coupling and / or positioning means may comprise two flats, formed for example by two projecting zones, circumferentially spaced from each other.

[0034] The cone may comprise a radially internal skin and a radially external skin, delimiting between them a box, the external skin forming at least in part said external surface of the ejection cone.

[0035] The box can be an acoustic box.

[0036] The acoustic enclosure helps limit noise pollution caused by the flow of gases from the turbine.

[0037] The radially inner skin and the radially outer skin may be connected by at least one radially extending wall.

[0038] The radially outer skin may extend axially upstream to the exhaust casing, the flange sectors being located radially inside the radially outer skin, the lugs being fixed to the radially inner skin.

[0039] The upstream end of the outer skin can then be moved a limited amount away from the exhaust casing.

[0040] An annular gasket may extend between the exhaust housing and the outer skin, so as to prevent the introduction of leakage air through the aforementioned clearance.

[0041] The upstream part of each sector can be fixed to a radial or axial downstream part of the exhaust casing, directly or by means of a connecting element.

[0042] The connecting element may have an L-shaped section.

[0043] The upstream part of each sector can be fixed to the exhaust housing by means of at least one bolt.

[0044] Each leg of each sector can be fixed to the exhaust cone by means of at least one bolt.

[0045] The invention also relates to a turbomachine comprising at least one assembly of the aforementioned type. Brief description of the figures

[0046] [ Fig. 1 ] is a schematic axial sectional view of a prior art turbomachine, [ Fig. 2 ] is a schematic axial sectional view of a propulsion unit of the prior art, [ Fig. 3 ] is a half-view in axial section of a part of a turbomachine ejection assembly of the prior art, [ Fig. 4 ] is a perspective view of a connecting flange between an ejector cone and an exhaust casing, in accordance with the prior art, [ Fig. 5 ] is a sectional view of part of an assembly according to the invention, [ Fig. 6 ] is a sectional and perspective view of part of an assembly according to the invention, [ Fig. 7 ] is a perspective view of part of an assembly according to the invention, [ Fig. 8 ] is a perspective view of a flange sector according to one embodiment of the invention, [ Fig. 9 ] is a perspective view of a flange sector according to another embodiment of the invention, [ Fig. 10 ] is a schematic axial sectional view of a part of a first embodiment of the assembly according to the invention, [ Fig. 11 ] is a view corresponding to the figure 10 , illustrating a second embodiment of the invention, [ Fig. 12 ] is a view corresponding to the figure 10 , illustrating a third embodiment of the invention, [ Fig. 13 ] is an exploded perspective view illustrating the case of a sector comprising a single leg, according to a first embodiment of the invention, [ Fig. 14 ] is a perspective view, illustrating the case of a sector comprising a single leg, according to a first embodiment of the invention, Detailed description of the invention

[0047] THE figures 5 à 8 illustrate an exhaust assembly for an aircraft turbomachine 1 according to one embodiment of the invention. This assembly comprises an exhaust casing 17 comprising, as previously, a radially external internal annular shell 19 and a radially external annular shell 20, connected by radial blades. Only the internal shell 19 is illustrated in figures 6 And 7 .

[0048] The assembly further comprises an ejection cone 18 comprising a radially internal skin 29 and a radially external skin 30, delimiting between them a box, for example an acoustic box 31. The radially external skin 30 is a so-called acoustic skin and extends axially upstream to the internal shell 19 of the exhaust casing 17. The upstream end 30a of the external skin 30 is spaced apart by an axial clearance j at least equal to 0.2 mm, for example, relative to the exhaust casing 17.

[0049] An annular seal 32 extends between the downstream end of the internal shell 19 of the exhaust casing 17 and the external skin 30, so as to prevent the introduction of leakage air through the aforementioned clearance j.

[0050] The downstream end of said internal shell 19 comprises an annular rim 33 extending axially, offset radially inwards relative to the radially external surface 34 of the internal shell 17 intended to delimit the primary vein 8.

[0051] A sectored annular flange 25 connects the annular rim 33 and the upstream end 29a of the internal skin 29 of the ejection cone 18.

[0052] The flange 25 is formed of several angular sectors 25a arranged circumferentially end to end, each flange sector 25a comprising an upstream portion 35 extending circumferentially from which one or more flat tabs 28 extend rectilinearly along an axis parallel to the axis X of the cone 18. The tabs 28 are regularly distributed over the circumference of the flange 25.

[0053] The upstream part 35 of each sector 25a is fixed to the rim 33 by means of fixing means comprising for example one or more bolts 36, here 4 bolts regularly distributed in the circumferential direction and sometimes illustrated schematically by axis lines.

[0054] The downstream end of each lug 28 is fixed to the upstream end 29a of the internal skin 29 of the cone 18 by means of fixing means comprising for example one or more bolts 37, here a single bolt, sometimes represented by center lines. Of course, fixing means by rivets or by welding are also possible for fixing the upstream part 35 or the lugs 28 of each sector 25a.

[0055] The number of legs 28 per sector 25a is here equal to 4, each flange 25 comprising 8 sectors.

[0056] Each leg 28 has a substantially constant thickness, a rectangular section and a generally rectangular shape, seen radially from the outside towards the inside.

[0057] The legs 28 are sufficiently soft and flexible to be elastically deformable and to compensate for the differential expansion effects between the cone 18 and the exhaust casing 17. Indeed, the exhaust casing 17 is for example made of metallic material, for example a nickel-based alloy, for example Inconel. The skins 29, 30 of the cone 18 are for example made of a ceramic matrix composite material, the differences in material generating such differential expansions depending on the operating temperature.

[0058] There figure 9 illustrates an embodiment where each sector 25a comprises a single tab 28, the number of sectors 25a of the flange 25 then being between 1 and 200. In this embodiment, the upstream part 35 is fixed to the casing 17 by means of at least two bolts 36.

[0059] It will be noted that the presence of at least two bolts 36 for fixing the upstream part 35 makes it possible to immobilize in rotation each sector 25a relative to an axis perpendicular to the axis X of the exhaust casing 17 and the cone 18, that is to say relative to an axis or a radial direction.

[0060] There figure 10 schematically illustrates the assembly of the sectors 25a of flange 25 relative to the downstream end of the internal shell 19 of the casing 17, on the one hand, and relative to the internal skin 29 of the cone 18, on the other hand.

[0061] There figure 11 illustrates another embodiment, where the axial rim 33 is formed by an intermediate connecting element 38. This element 38 comprises a radial annular part 39, fixed by any suitable means to a radial annular part 40 of the downstream end of the internal ferrule 19, and an axial or cylindrical annular part, forming the rim 33 used for fixing the upstream part 35 of each sector 25a.

[0062] There figure 12 illustrates yet another embodiment in which the upstream end 35 of each sector 25a comprises a radial rim 39 extending radially outwards, fixed to a radial annular portion 40 of the downstream end of the internal shell 19 of the exhaust casing 17.

[0063] THE figures 13 et 14 each illustrate an embodiment in which each sector 25a comprises a single tab 28.

[0064] In the embodiment of the figure 13 , the upstream part 35 comprises a hole 41 allowing the passage of a fixing means, for example a screw of a bolt 36, and a stud 42 engaged in an orifice or a recess 43 of complementary shape of the rim 33, the fixing means 36 being circumferentially offset from the stud 42. The fixing means 36, the orifice 42 and the recess 43 thus form means making it possible to prevent the rotation of the sector 25a relative to an axis or a radial direction.

[0065] In the embodiment of the figure 14 , the upstream part 35 comprises two flats formed by studs 44 extending radially inwards for example. The studs 44 are circumferentially spaced from each other and bear on the downstream edge of the axial rim 33. The upstream part 35 also comprises fixing means, formed by one or more bolts 37 for example.

Claims

1. Assembly for a turbomachine (1) including an exhaust cone (18) and an exhaust case (17) including an annular inner shell (19), the exhaust cone (18) and the exhaust case (17) extending about an axis (X), the exhaust cone (18) including an outer surface extending in the projection of said inner shell (19), the exhaust cone (18) being connected to the exhaust case (17) via a flange (25), said flange (25) including an upstream portion (35) fastened to the exhaust case (17) and lugs (28) extending downstream from said upstream portion (35), the exhaust cone (18) being fastened to said lugs (28), characterized in that the flange (25) is segmented and consists of several angular segments (25a) arranged circumferentially adjacent, each flange segment (25a) including at least one lug (28) extending in a rectilinear manner along an axis parallel with the axis (X) of the cone (18).

2. Assembly according to claim 1, characterized in that each flange segment (25a) extends over an angular range less than 180°3. Assembly according to claim 1 or 2, characterized in that each flange segment (25a) includes between 1 and 100 lugs (28), preferably between 1 and 10 lugs (28), preferably between 3 and 6 lugs (28).

4. Assembly according to one of claims 1 to 3, characterized in that it includes means for coupling in rotation and / or positioning (36, 42, 44) each flange segment (25a).

5. Assembly according to claim 4, characterized in that the means for coupling in rotation and / or positioning include at least one positioning stud (42) formed on the corresponding segment (25a), engaged in a complementary recess or orifice (43) of the exhaust case (17) or the cone (18), or vice versa.

6. Assembly according to claim 4 or 5, characterized in that the means for coupling in rotation and / or positioning include at least one flat section (44) formed on the corresponding segment (25a), pressing on an edge or a corresponding planar surface (33) of the exhaust case (17) or the cone, or vice versa.

7. Assembly according to one of claims 1 to 3, characterized in that the cone (18) includes a radially inner skin (29) and a radially outer skin (30), defining a chamber (31) between them, the outer skin (30) forming at least partially said outer surface of the exhaust cone (18).

8. Assembly according to claim 7, characterized in that the radially outer skin (30) extends axially toward the upstream to the exhaust case (17), the flange segments (25a) being located radially inside the radially outer skin (30), the lugs (28) being fastened to the radially inner skin (29).

9. Assembly according to one of claims 1 to 8, characterized in that the upstream portion (35) of each segment (25a) is fastened onto a radial (40) or axial (33) downstream portion of the exhaust case (17), directly or via a connecting element (38).

10. Turbomachine (1) including at least one assembly according to one of claims 1 to 9.