Assembly for a turbine engine

Abstract

The present invention relates to an assembly (100) for a turbine engine, the assembly (100) comprising: - an exhaust cone including an annular wall (122, 121) made of a ceramic matrix composite material, - a metal casing arranged upstream of the exhaust cone, and - a connecting flange (110) connecting the annular wall (122, 121) to the casing, wherein the assembly (100) further comprises a bolt (200) extending along a second axis (X2) including a screw (210) and a nut (220), the screw (210) passing through an opening (115, 116) of the annular wall (122, 121) and of the connecting flange (110), respectively, wherein the nut (220) comprises an outer annular surface (226) including a first outer annular surface portion flaring radially outwards, the first outer annular surface portion being formed of a plurality of faces arranged circumferentially end-to-end and joined in pairs by an edge.

Description

Description Title: TURBOMACHINE ASSEMBLY Technical field

[0001] The present disclosure relates to an assembly for a turbomachine, in particular for the afterbody of a turbomachine. It also relates to a turbomachine comprising such an assembly. Prior art

[0002] Figures 1 and 2 schematically represent a turbomachine 1 with axis X1, hereinafter referred to as the first axis X1, for example a bypass turbojet. Such a turbomachine 1 generally comprises, from upstream AM to downstream AV, a fan 2, a low-pressure compressor 3, a high-pressure compressor 4, a combustion chamber 5, a high-pressure turbine 6, a low-pressure turbine 7 and an exhaust system downstream of the body of the turbomachine. The first axis X1 is notably coincident with the axis of rotation of the rotors of the turbomachine 1.

[0003] The gas flow F, in particular air, entering upstream of the turbomachine 1 first circulates through the fan 2 and then divides into a primary flow F1 flowing in a circulation vein called the primary annular vein 8, and into a secondary flow F2 flowing in a circulation vein called the secondary annular vein 9 surrounding the primary annular vein 8.

[0004] In this document, the terms “upstream” and “downstream” are defined, unless otherwise indicated, in relation to the direction of flow of the gases within the turbomachine 1. In addition, the terms “longitudinal”, “radial” and “circumferential” are defined in relation to the axis X1 of the turbomachine 1 and the terms “inner” and “outer”, and “internal” and “external”, are then defined in the radial direction in relation to the axis X1 of the turbomachine.

[0005] Downstream of the turbomachine, the exhaust system ensures the evacuation of the hot gases leaving the low-pressure turbine 7 through the primary annular flow path 8. Conventionally, the exhaust system comprises an exhaust casing 130 and an ejection cone 120, also referred to as an exhaust cone, arranged downstream of the exhaust casing 130. The exhaust casing 130 generally has an inner annular shell 131 and an outer annular shell 132, forming between them an annular space delimiting the primary annular flow path 8 at the outlet of the low-pressure turbine. The gases leaving the low-pressure turbine then circulate around the ejection cone 120 from upstream to downstream. In other words, the ejection cone 120 forms an inner delimitation of the primary annular flow path. The ejection cone 120 is mechanically connected to the internal annular shell 131 of the casing 130 by means of a connecting flange mechanically secured to the casing 130.

[0006] Figure 3 illustrates an example of an ejection cone 120. The ejection cone 120 generally comprises an outer annular wall 122 and an inner annular wall 121 arranged radially inside the outer annular wall 122. Partitions 123, usually planar or curves, can extend radially between the inner annular wall 121 and the outer annular wall 122, so as to form an acoustic box suitable for attenuating acoustic waves.

[0007] Furthermore, with the aim of reducing the mass of turbomachines, it is envisaged to use ceramic matrix composite materials, designated CMC materials, for many parts of the turbomachine. In this context, the ejection cone 120 can be made of ceramic matrix composite material. The internal annular shell 131 of the exhaust casing 130 and the connecting flange remain conventionally metallic, for example made of titanium alloy, in order to ensure a certain mechanical strength.

[0008] This use of CMC materials, which have particular characteristics of stiffness and thermal expansion, creates problems of thermal expansion differentials during operation. This impacts the assembly of the various aforementioned parts together.

[0009] To compensate for these thermal expansion differentials, a classic bolted connection solution consists of using a screw and a nut with a washer and / or a spacer. The screws can, for example, consist of standard screws. The nuts are usually made of a nickel-based superalloy, compatible with the operating temperatures of the parts. The use of a spacer in a material with suitable thermal expansion makes it possible to at least partially compensate for the expansion difference between the parts. This also makes it possible to partially compensate for the drop in stiffness at high temperatures. Document WO2022129722A1 describes such an example of a spacer.

[0010] This document aims to solve at least in part the problems mentioned above, by proposing a turbomachine assembly making it possible to improve the fixing of an annular wall of the ejection cone in the presence of thermal expansion constraints. Summary

[0011] This disclosure improves the situation.

[0012] An assembly is proposed for a turbomachine with an axis hereinafter referred to as the first axis. The assembly comprises an ejection cone intended to allow a flow of gas according to a primary flow around it from upstream to downstream along the first axis and a metal casing arranged upstream of the ejection cone. The ejection cone comprises an annular wall made of a composite material, in particular a ceramic matrix material. The assembly comprises a connecting flange connecting the annular wall to the casing. The assembly further comprises a bolt extending along a second axis and comprising a screw and a nut, the nut being configured to cooperate with the screw. The screw passes through an opening respectively in the annular wall and the connecting flange.The nut extends along the second axis between a first end, which may in particular correspond to a radially external end of the nut, configured to bear against one of the annular wall or the connecting flange and a second end, which may in particular correspond to a radially internal end of the nut, opposite the first end. The nut comprises an external annular surface comprising a first external annular surface portion. flaring radially outwards. The first outer annular surface portion is formed of a plurality of faces arranged circumferentially end-to-end and joined two by two by an edge.

[0013] The implementation of the first portion of external annular surface, widening radially outwards and being formed of a plurality of faces arranged circumferentially end-to-end and joined two by two by an edge, offers the considerable advantage of allowing a saving of material and / or spatial size while ensuring sufficient mechanical strength of the bolt. Indeed, the radially widening edges provide a stiffening function for the nut. The faces and edges can therefore be adjusted in order to optimize the mass of the nut while guaranteeing sufficient mechanical strength thereof.

[0014] The features set out in the following paragraphs may, optionally, be implemented, independently of each other or in combination with each other:

[0015] Advantageously, the ejection cone comprises an inner annular wall and an outer annular wall. The connecting flange comprises a radial annular wall whose radially outer end is connected to a cylindrical wall. The downstream end of the cylindrical wall is connected to flexible tabs extending longitudinally along the first axis.

[0016] According to a first embodiment, said annular wall of the ejection cone is formed by the outer annular wall of the ejection cone. The screw passes through an opening respectively of the outer annular wall and of the cylindrical wall of the connecting flange to fix together the outer annular wall of the ejection cone and the cylindrical wall of the connecting flange. Thus, in this embodiment, the connecting flange is directly fixed by the nut according to the invention to the outer annular wall of the ejection cone, this outer annular wall serving as a flow surface for the hot gas flow.

[0017] According to a second embodiment, said annular wall of the ejection cone comprises the inner annular wall of the ejection cone. The screw passes through an opening respectively of the inner annular wall and of one of the flexible tabs of the connecting flange to fix together the inner annular wall of the ejection cone and the corresponding flexible tab of the connecting flange. In this embodiment, the connecting flange is directly fixed by the nut according to the invention to the inner annular wall of the ejection cone, the outer annular wall being able to be left free at its upstream end.

[0018] The nut advantageously comprises an internal annular surface defining a passage orifice for the screw. The internal annular surface comprises in particular a first portion of threaded internal annular surface intended to cooperate with the screw and a second portion of internal annular surface interposed along the second axis between the first portion of internal annular surface and the first end of the nut. The second portion of internal annular surface defines an annular clearance with the screw.

[0019] The implementation of the internal annular surface allows the nut to perform both a spacer function thanks to the annular clearance between the second portion of the internal annular surface and the screw and a nut function thanks to the first portion of annular surface which is threaded and which ensures a grip between the screw and the nut. This dual function of the nut makes it possible to compensate for a thermal expansion differential between the parts assembled by the bolt, namely the annular wall of the ejection cone and the connecting flange. The connecting flange can be made of a metallic material, or alternatively of a ceramic matrix composite material. In other words, the assembly relates in particular to at least one part made of ceramic matrix composite material, for example a part made of ceramic matrix composite material and a part made of metallic material or two parts made of ceramic matrix composite material.Furthermore, the use of a single component for the nut to fulfill both the nut and spacer functions also makes it possible to use only one material for these two functions and to facilitate the manufacturing stages of the assembly, in particular the procurement, assembly and fitting of the parts.

[0020] The first portion of the external annular surface may flare at an angle of between 30° and 90°, preferably substantially equal to 45°.

[0021] The faces of the first portion of external annular surface advantageously extend over a first dimension along the second axis of between 20% and 50% of a length of the nut.

[0022] The faces of the first portion of the external annular surface may extend along the second axis between the same first axial position and the same second axial position along the second axis. This configuration has the advantage of being easy to produce.

[0023] The faces of the first portion of the external annular surface may comprise at least first faces and second faces arranged alternately and axially offset along the second axis by a fourth dimension of between 0% and 30% of the first dimension. This configuration makes it possible to further improve the optimization of the space saving of the nut while guaranteeing a sufficient level of mechanical strength of the latter.

[0024] The faces of the first outer annular surface portion may advantageously extend along the second axis over at least two different dimensions, preferably in an alternating manner. For example, the faces of the first outer annular surface portion may extend along the second axis over two or three different dimensions.

[0025] The outer annular surface may, advantageously, further comprise a second portion of outer annular surface interposed between the first portion of outer annular surface and the first end of the nut.

[0026] The second portion of external annular surface may have a shape of revolution around the second axis and extend along the second axis over a second dimension of between 10% and 80% of the length of the nut.

[0027] The second outer annular surface portion may have a cylindrical shape.

[0028] The second portion of external annular surface may have a conical shape widening at an angle strictly greater than 0° and less than or equal to 45°, preferably less than or equal to 10°, for example equal to 3.3°.

[0029] The outer annular surface may advantageously further comprise a third portion of outer annular surface interposed between the first portion of outer annular surface and the second end of the nut. The third portion of outer annular surface may extend substantially parallel to the second axis over a third dimension of between 20% and 50% of the length of the nut.

[0030] The third portion of external annular surface may in particular have a polygonal shape, in particular hexagonal, extending along the second axis. The edges of the first portion of external annular surface may be formed in the extension of the edges of the third portion of external annular surface.

[0031] The first portion of external annular surface may in particular comprise between four and eight faces, for example six faces.

[0032] The first portion of internal annular surface may have a dimension along the second axis of between 20% and 90%, for example between 20% and 50%, preferably substantially equal to 40%, of the length of the nut.

[0033] The second portion of internal annular surface may have a dimension along the second axis of between 10% and 80%, for example between 50% and 70%, preferably substantially equal to 60%, of the length of the nut.

[0034] At least one or each of the edges may be included in a plane. Said plane may be parallel to the second axis or inclined with respect to the second axis. The planes in each of which at least one of the edges is inscribed may be concurrent with the second axis.

[0035] Advantageously, the nut is made of the same material, preferably steel, in particular A286 steel. This steel has advantageous thermal expansion properties to compensate for a thermal expansion differential between the annular wall of the ejection cone and the connecting flange.

[0036] Advantageously, the screw is made of a material having a coefficient of thermal expansion lower than that of the nut material. The screw is preferably made of a nickel-chromium alloy, for example an alloy of the Inconel 718 type. Making the nut of a material having a coefficient of expansion higher than that of the screw advantageously makes it possible to maintain the clamping of the annular wall of the ejection cone and the connecting flange together despite possible thermal expansion effects.

[0037] The ejection cone may advantageously comprise an outer annular wall made of a ceramic matrix composite material and an inner annular wall arranged radially inside the outer annular wall. The outer annular wall may form said annular wall of the ejection cone. Alternatively, the inner annular wall may form said annular wall of the ejection cone.

[0038] According to another aspect, there is provided a turbomachine comprising the assembly as previously described. Brief description of the drawings

[0039] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analyzing the attached drawings, in which:

[0040] [Fig. 1] schematically illustrates a partial sectional view of a turbomachine according to the prior art.

[0041] [Fig. 2] schematically illustrates a partial sectional view of a turbomachine according to the prior art.

[0042] [Fig. 3] schematically illustrates a partial sectional view of a turbomachine ejection cone according to the prior art.

[0043] [Fig. 4] schematically illustrates a partial sectional view of an assembly according to a first embodiment.

[0044] [Fig. 5] schematically illustrates a partial sectional view of an assembly according to a second embodiment.

[0045] [Fig. 6] schematically illustrates respectively a first example of a nut (Figure 6A) according to this document and a second example of a nut (Figure 6B) according to this document. Description of the embodiments

[0046] Reference is now made to Figures 4 and 5 schematically representing a truncated partial view respectively of a first embodiment and a second embodiment of an assembly 100 according to the present document. Preferably, such an assembly 100 can be implemented in a turbomachine of axis X1, designated first longitudinal axis X1, as previously described with reference to Figures 1, 2 and 3. In addition, the present document also relates to any type of turbomachine comprising the assembly 100, and in particular a turbojet for aircraft, preferably a double-flow turbojet.

[0047] The assembly 100 comprises an ejection cone 120 intended to allow a flow of gas according to a primary flow F1 around it from upstream to downstream along the first axis X1 and a metal casing 130 arranged upstream of the ejection cone 120. The ejection cone 120 comprises an outer annular wall 122 and an inner annular wall 121, at least one of which is made of a composite material, in particular a ceramic matrix. In another possible embodiment, the two outer annular walls 122 and inner 121 may be made of a composite material. The assembly 100 comprises a connecting flange 110 connecting the outer annular wall 122 and / or inner 121 to the casing 130 as appears in each of the embodiments described with reference to FIGS. 4 and 5.

[0048] As illustrated in Figures 4 and 5, the casing 130 comprises in particular an internal annular shell 131 forming an internal delimitation of a gas flow according to the primary flow F1. The downstream end of the internal annular shell 131 is connected to a radial annular wall 133. This radial annular wall 133 of the casing is fixed by bolting to a radial annular wall 112 of the connecting flange which is therefore interposed longitudinally between the internal annular wall 121 and the casing 130. The upstream end 124 of the external annular wall 122 is advantageously arranged in the aerodynamic extension of the internal annular shell 131 of the casing 11 so as to facilitate the flow of hot air.

[0049] The connecting flange 110 may be metallic, for example made of titanium alloy.

[0050] The connecting flange 110 comprises the radial annular wall 112, the radially external end of which is connected to a cylindrical wall 113. The downstream end of the cylindrical wall 113 is connected to flexible tabs 114 extending longitudinally along the first axis X1. The flexible tabs 114 are preferably regularly distributed over the circumference of the connecting flange 110. The cylindrical wall 113 comprises an annular row of openings 115. The downstream ends of the flexible tabs 114 each comprise an opening 116 for the passage of a fixing screw at the upstream end of the internal annular wall 121 of the ejection cone 120.

[0051] With reference to Figures 4 and 5, the assembly 100 further comprises a bolt 200 extending radially along a second radial axis X2. The bolt 200 comprises a screw 210 and a nut 220, the nut 220 being configured to cooperate with the screw 210. The nut 220 extends along the second axis X2 between a first end 221, which may in particular correspond to a radially external end of the nut (as illustrated in Figures 4 and 5) and a second end 222, which may in particular correspond to a radially internal end of the nut (as illustrated in Figures 4 and 5) opposite the first end 221.

[0052] According to the first embodiment illustrated in Figure 4, the connecting flange 110 connects the inner annular wall 121 and the outer annular wall 122 to the casing 130. The outer annular wall 122 is made of a composite material, in particular a ceramic matrix. In this embodiment, the inner annular wall 121 can be made of a composite material or a metallic material. The screw 210 passes through an opening 115 of the outer annular wall 122 and a cylindrical wall opening 113 of the connecting flange. In addition, the first end 221 of the nut 220 is configured to bear against one of the outer annular wall 122 and said cylindrical wall 113 of the connecting flange. In particular, in Figure 4, the first end 221 of the nut 220 bears against the cylindrical wall 113 of the connecting flange.Indeed, the junction between the connecting flange and the external annular wall is subject to a strong thermal gradient due to the flow of hot gases against the external annular wall, hence the interest in implementing the bolt 200 at this location according to the present disclosure.

[0053] According to the second embodiment illustrated in Figure 5, the outer annular wall 122 is advantageously left free with respect to the upstream inner annular wall 121. Thus, the inner annular wall 121 and the outer annular wall 122 will be able to withstand a thermal expansion gap between them. This makes it possible to ensure the structural strength of the assembly in a context of thermal gradient between the internal annular wall 121 (in contact with a “colder” cavity) and the external annular wall 122 (in contact with the primary annular flow vein for hot gases) which can generate high thermomechanical stresses.

[0054] An assembly according to the second embodiment is illustrated in Figure 5. The inner annular wall is made of a composite material, in particular a ceramic matrix. The screw 210 passes through an opening 126 of the inner annular wall 121 and an opening 116 of the lugs 114 of the connecting flange. The first end 221 of the nut 220 bears against one of the inner annular wall 121 and one of the flexible lugs 114 of the connecting flange. In particular, in Figure 5, the first end 221 of the nut 220 bears against one of the flexible lugs 114 of the connecting flange.

[0055] The bolt 200 described more precisely below can be applied to the first embodiment (figure 4) and to the second embodiment (figure 5), this bolt therefore comprising a screw 210 as illustrated in figures 4 and 5 and a nut illustrated in figures 4 and 5 and better visible in figures 6A and 6B.

[0056] The screw 210 comprises in particular a threaded rod 211 and a screw head 212.

[0057] The screw 210 is preferably made of a material having a coefficient of thermal expansion lower than that of the material of the nut 220, which advantageously makes it possible to maintain the tightening of the annular wall of the ejection cone and the connecting flange together despite possible thermal expansion effects. The screw 210 is preferably made of a nickel-chromium alloy, for example an alloy of the Inconel 718 type.

[0058] The nut is advantageously made of the same material, preferably steel, in particular A286 steel. This steel has advantageous thermal expansion properties to compensate for a thermal expansion differential between the annular wall of the ejection cone and the connecting flange.

[0059] Figures 6A and 6B respectively illustrate a first and a second nut variant for forming a bolt for the assembly according to the present document according to the first or second embodiment of the assembly 100.

[0060] The nut 220 may comprise an internal annular surface 223 defining an orifice for the passage of the screw 210. The internal annular surface 223 comprises a first portion of internal annular surface 224 threaded for cooperating with the screw 210 and a second portion of internal annular surface 225 interposed along the second axis X2 between the first portion of internal annular surface 224 and the first end 221 of the nut 220. The second portion of internal annular surface 225 defines with the screw 210 an annular clearance 213.

[0061] The implementation of the internal annular surface allows the nut to perform both a spacer function thanks to the annular clearance between the second portion of the internal annular surface and the screw and a nut function thanks to the first portion of the annular surface which is threaded and which ensures a grip between the screw and the nut. This dual function of the nut makes it possible to compensate for a thermal expansion differential between the parts assembled by the bolt, namely the annular wall of the ejection cone and the connecting flange. The annular clearance 213 is in particular non-zero during assembly in order to be able to ensure the spacer function of the assembly.

[0062] Furthermore, the use of a single component for the nut to fulfill both the nut and spacer functions also makes it possible to use only one material for these two functions and to facilitate the manufacturing stages of the assembly, in particular the procurement, assembly and fitting of the parts.

[0063] The first internal annular surface portion 224 may have a dimension along the second axis of between 20% and 90%, for example between 20% and 50%, preferably substantially equal to 40%, of the length of the nut. It is also possible to fix the dimension of the first internal annular surface portion 224 so that it is between 1 and 2 times the diameter of the screw 210.

[0064] The second internal annular surface portion 225 may have a dimension along the second axis of between 10% and 80%, for example between 50% and 70%, preferably substantially equal to 60%, of the length of the nut.

[0065] The nut 220 comprises an outer annular surface 226 having a first outer annular surface portion 227 widening radially outwards. The first outer annular surface portion 227 is formed of a plurality of faces 228 arranged circumferentially end-to-end and joined two by two by an edge 229.

[0066] The implementation of the first portion of external annular surface, widening radially outwards and being formed of a plurality of faces arranged circumferentially end-to-end and joined two by two by an edge, offers the considerable advantage of allowing a saving of material and / or spatial size while ensuring sufficient mechanical strength of the bolt. Indeed, the radially widening edges provide a stiffening function for the nut. The faces and edges can therefore be adjusted in order to optimize the mass of the nut while guaranteeing sufficient mechanical strength thereof.

[0067] The first portion of external annular surface 227 may flare in the form of a fillet, in particular with a radius of between 0.5 mm and 10 mm, for example substantially equal to 5 mm.

[0068] The first portion of external annular surface 227 can flare at an angle of between 30° and 90°, preferably substantially equal to 45°.

[0069] The faces 228 of the first portion of external annular surface 227 extend in particular over a first dimension D1 along the second axis X2 comprised between 20% and 50% of a length D of the nut 220.

[0070] As illustrated in Figure 6A, the different faces 228 of the first external annular surface portion 227 can extend along the second axis X2 between the same first axial position and the same second axial position along the second axis X2. This configuration has the advantage of being easy to produce.

[0071] As illustrated in Figure 6B, the faces 228 of the first external annular surface portion 227 may comprise at least first faces 228a and second faces 228b arranged alternately and axially offset along the second axis X2 by a fourth dimension D4 comprised between 0% and 30% of the first dimension D1. For example, the fourth dimension D4 may be less than or equal to 3 mm, preferably equal to 1 mm. Said at least first faces and second faces may thus be axially offset by said fourth distance at at least one end along the second axis X2, for example at one end or at both opposite ends of said first and second faces. This configuration makes it possible to further improve the optimization of the space saving of the nut while guaranteeing a sufficient level of mechanical strength of the latter.

[0072] The faces 228 of the first external annular surface portion 227 may advantageously extend along the second axis X2 over at least two different dimensions, preferably in an alternating manner. For example, the faces of the first external annular surface portion may extend along the second axis over two or three different dimensions.

[0073] The outer annular surface 226 may further comprise a second outer annular surface portion 230 interposed between the first outer annular surface portion 227 and the first end 221 of the nut 220.

[0074] The second portion of external annular surface 230 may have a shape of revolution around the second axis X2 and extend along the second axis X2 over a second dimension D2 of between 10% and 80% of the length D of the nut 220.

[0075] The second outer annular surface portion 230 may have a cylindrical shape.

[0076] The second external annular surface portion 230 may have a conical shape widening by an angle strictly greater than 0° and less than or equal to 45°, preferably less than or equal to 10°, for example of the order of 3°, more precisely equal to 3.3°.

[0077] The external annular surface 226 may further comprise a third external annular surface portion 231 interposed between the first external annular surface portion 227 and the second end 222 of the nut 220. The third external annular surface portion 231 may extend substantially parallel to the second axis X2 over a third dimension D3 of between 20% and 50% of the length D of the nut 220.

[0078] The third portion of external annular surface may in particular have a polygonal shape, in particular hexagonal, extending along the second axis. The edges of the first portion of external annular surface may be formed in the extension of the edges of the third portion of external annular surface.

[0079] The third portion of annular surface may have at its end a nut braking element.

[0080] The first portion of external annular surface may in particular comprise between four and eight faces, for example six faces.

[0081] Each of the edges 229 may advantageously be oriented substantially along the second axis X2. Each edge 229 may also be included in a plane which may include the second axis X2 or be parallel to it. Said plane including the edge 229 may also be inclined relative to the axis X2.

[0082] For example, for an annular wall with a thickness of approximately 3.57 mm, the screw may have a length of 27.7 mm, the nut may have a length of 16.5 mm, a maximum external diameter of 15 mm and an external radial dimension of the third portion of the external annular surface of 6.35 mm.

Claims

Claims

1. Assembly (100) for turbomachine (1) of first axis (X1), the assembly (100) comprising: - an ejection cone (120) intended to allow a flow of gas according to a primary flow (F1) around it from upstream to downstream along the first axis (X1), the ejection cone (120) comprising an annular wall (122, 121) made of a composite material, preferably with a ceramic matrix, - a metal casing (130) arranged upstream of the ejection cone (120), - a connecting flange (110) connecting the annular wall (122, 121) to the casing (130), wherein the assembly (100) further comprises a bolt (200) extending along a second axis (X2) and comprising a screw (210) and a nut (220), the nut (220) being configured to cooperate with the screw (210), the screw (210) passing through an opening (115, 116, 125, 126) respectively of the annular wall (122, 121) and of the connecting flange (110), the nut (220) extending along the second axis (X2) between a first end (221) configured to bear against one of the annular wall (122, 121) or of the connecting flange (110) and a second end (222) opposite the first end (221), wherein the nut (220) comprises an outer annular surface (226) having a first portion of outer annular surface (227) flaring radially outwards,the first external annular surface portion (227) being formed of a plurality of faces (228) arranged circumferentially end-to-end and joined two by two by an edge (229).,

2. Assembly (100) according to claim 1, in which the nut (220) comprises an internal annular surface (223) defining a passage orifice for the screw (210), the internal annular surface (223) comprising a first portion of internal annular surface (224) threaded intended to cooperate with the screw (210) and a second portion of internal annular surface (225) interposed along the second axis (X2) between the first portion of internal annular surface (224) and the first end (221) of the nut (220), the second portion of internal annular surface (225) defining with the screw (210) an annular clearance (213).

3. Assembly (100) according to one of the preceding claims, in which the faces (228) of the first external annular surface portion (227) extend over a first dimension (D1) along the second axis (X2) between 20% and 50% of a length (D) of the nut (220).

4. Assembly (100) according to one of the preceding claims, in which the faces (228) of the first external annular surface portion (227) extend along the second axis (X2) between the same first axial position and the same second axial position along the second axis (X2).

5. Assembly (100) according to one of claims 1 to 3, in which the faces (228) of the first portion of external annular surface (227) comprise at least first faces (228a) and second faces (228b) arranged alternately and axially offset according to the second axis (X2) of a fourth dimension (D4) between 0% and 30% of the first dimension (D1).

6. Assembly (100) according to one of claims 1 to 3 or 5, in which the faces (228) of the first external annular surface portion (227) extend along the second axis (X2) over at least two different dimensions, preferably in an alternating manner.

7. Assembly (100) according to one of the preceding claims, in which the external annular surface (226) further comprises a second external annular surface portion (230) interposed between the first external annular surface portion (227) and the first end (221) of the nut (220), the second external annular surface portion (230) having a shape of revolution around the second axis (X2) and extending along the second axis (X2) over a second dimension (D2) comprised between 10% and 80% of the length (D) of the nut (220). [Claim s] Assembly (100) according to the preceding claim, in which the second external annular surface portion (230) has a conical shape widening by an angle strictly greater than 0° and less than or equal to 45°, preferably less than or equal to 10°, for example equal to 3.3°.

9. Assembly according to one of the preceding claims, in which the external annular surface (226) further comprises a third external annular surface portion (231) interposed between the first external annular surface portion (227) and the second end (222) of the nut (220), the third external annular surface portion (231) extending substantially parallel to the second axis (X2) over a third dimension (D3) between 20% and 50% of the length (D) of the nut (220).

10. Assembly (100) according to one of the preceding claims, in which the nut (220) is made of the same material, preferably A286 steel.

11. Assembly (100) according to the preceding claim, in which the screw (210) is made of a material having a coefficient of thermal expansion lower than that of the material of the nut (220), the screw (210) preferably being made of a nickel-chromium alloy.

12. Assembly (100) according to one of the preceding claims, in which the ejection cone (120) comprises an outer annular wall (122) made of a ceramic matrix composite material and an inner annular wall (121) arranged radially inside the outer annular wall (122), the outer annular wall (122) forming said annular wall of the ejection cone.

13. Turbomachine (1) comprising the assembly (100) according to one of the preceding claims.

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