SERVICE ARM FOR A TURBOMACH EXHAUST HOUSING

Description

FIELD OF INVENTION

[0001] The present invention relates to turbomachines, in particular aeronautical turbomachines, and more particularly to an aircraft turbomachine exhaust casing.

[0002] The invention relates more particularly, but not exclusively, to an exhaust casing intended for use in a USF type engine (English acronym for "Unducted Single Fan"), comprising a movable blade and a fixed blade of an unducted aircraft engine fan. STATE OF THE ART

[0003] A turbomachine has a longitudinal axis around which it extends and typically comprises, from upstream to downstream in the direction of gas flow, a fan, a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine, and a low-pressure turbine including an exhaust casing. The exhaust casing helps to define the primary fluid path (or primary gas flow) through the turbomachine and, via the bearing supports, ensures concentricity between the rotor and stator of the turbomachine, as well as the attachment of the engine's downstream end to the nacelle.

[0004] This exhaust housing conventionally comprises a hub, centered on the turbomachine's axis, an outer shell coaxial with the hub, and a set of arms connecting the hub and the outer shell. The arms are located in the primary flow and are therefore hotter than the outer shell and the hub. Consequently, the exhaust housing arms are subjected to significant thermal gradients, which generate mechanical stresses that impact the lifespan of the exhaust housing.

[0005] A turbomachine may include other similar casings such as an intermediate casing (interposed between a low-pressure compressor and a high-pressure compressor of the turbomachine, and is therefore traversed by a flow of gas exiting the low-pressure compressor and intended to supply the high-pressure compressor) or an inter-turbine casing (interposed between the high-pressure turbine and the low-pressure turbine).

[0006] The operation of a conventional turbomachine involves, among other things, the passage of electrical cables and the circulation of various fluids through the turbomachine, such as air, oil, or oiled air. To transport these fluids, it is common practice to incorporate piping within the turbomachine's structure itself. Some of these piping, called service tubes, must connect radially external parts of the turbomachine to radially internal parts, thus carrying both primary and secondary airflows.

[0007] It is known to route auxiliary components such as service tubes within hollow arms of housings, such as the hollow arms of the exhaust housing, without disrupting the flow within the channel thanks to their internal cavity. Generally, each of these auxiliary components allows for the connection of at least one piece of equipment located radially inside the channel to at least one piece of equipment located radially outside the channel of the housing.

[0008] As part of the USF development, numerous power electrical harnesses must pass through the exhaust casing to accommodate electric hybridization and the integration of speed sensors on the low-pressure turbine shaft. However, current technologies cannot withstand the typical temperatures experienced by the exhaust casing arms in such a turbomachine. Therefore, the harnesses must be cooled by circulating air around them in a confined space. An example is described in patent application FR 3053387. Existing solutions, however, do not allow for harness cooling within a small footprint, while also accounting for thermal expansion caused by the airflow through the exhaust casing and the risk of vibration from the electrical harnesses. DESCRIPTION OF THE INVENTION

[0009] One aim of the invention is to remedy the aforementioned disadvantages by proposing a solution for passing electrical harnesses in a simple, ergonomic and unobtrusive manner through an arm of an exhaust housing, taking into account the severe thermal environment to which the arms are subjected and also to resist the vibrations generated by the engine.

[0010] Accordingly to a first aspect of the invention, a turbomachine housing according to claim 1 and a turbomachine according to claim 10 are proposed. Embodiments are described in the dependent claims. The turbomachine housing may, for example, be an exhaust housing and comprise: an internal hub extending around an axis; an external ferrule coaxial with the internal hub; a plurality of arms extending from the internal hub to the external ferrule, each arm having a wall; electrical harnesses configured to connect a first electrical equipment arranged radially outside the external ferrule and a second electrical equipment arranged radially inside the internal hub; and a sleeve extending within an arm at a distance from the arm wall, the sleeve comprising an internal face delimiting an internal cavity configured to receive electrical harnesses; and at least one shim mounted in the sleeve, each shim being configured to keep the electrical harnesses away from an internal face of the sleeve.

[0011] Some preferred but not exhaustive characteristics of the crankcase according to the first aspect are the following, taken individually or in combination: the sheath houses at least two electrical harnesses, the wedge being further configured to keep the at least two electrical harnesses apart from each other within the sheath; the wedge includes at least two through passages, each electrical harness being housed in a corresponding through passage; the housing further includes a ventilation system in fluidic communication with the internal cavity of the sheath; the housing further includes the second electrical equipment arranged radially inside the internal hub, the sheath further extending between the internal hub and the second electrical equipment so that the ventilation system is in fluidic communication with the second electrical equipment;the wedge further includes at least one notch configured to allow fluid circulation between the outer shell and the inner hub in order to establish fluid communication between the second electrical equipment and the ventilation system; the housing further includes thermal insulation fixed to an outer face of the sleeve; the sleeve is mounted in a movable manner relative to at least one of the outer shell and the inner hub by allowing radial movement of the sleeve relative to the outer shell and / or relative to the inner hub; the wedge has bearing areas configured to come into contact with the inner face of the sleeve in order to keep the electrical harnesses away from the inner face of the sleeve, the bearing areas being able to be curved or flat;and / or the housing comprises at least two electrical harnesses and at least two sheath portions forming a sheath that extend within the arm, the at least two sheath portions being arranged end-to-end along the electrical harnesses so as to form a sheath that surrounds the electrical harnesses.

[0012] According to a second aspect, the invention provides a turbomachine comprising a casing conforming to the first aspect. In one embodiment, the casing is located in a primary flow of the turbomachine. The turbomachine may further comprise a single, unshrouded fan. Alternatively, the turbomachine may be of the USF type or comprise a shrouded fan.

[0013] According to a third aspect, the invention provides an aircraft comprising a turbomachine having a casing conforming to the first aspect. The turbomachine may also conform to the second aspect. DESCRIPTION OF THE FIGURES

[0014] Other features, purposes and advantages of the invention will become apparent from the following description, which is purely illustrative and not limiting, and which should be read in conjunction with the accompanying drawings on which: There figure 1 is a partial view of an exhaust housing according to an embodiment of the invention; The figure 2 represents the scabbard and harness of the figure 1 ; There figure 3a is a top view of a first example of a shim that can be used in a housing according to the invention; The figure 3b is a top view of a second example of an embodiment of a shim that can be used in a housing according to the invention; The figure 4 is a partial cross-sectional view taken in a plane including the X-axis and a radial axis passing through the arm of the housing of the figure 1 ; There figure 5is a schematic view of an example of a turbomachine which may include an exhaust casing according to an embodiment of the invention.

[0015] Across all figures, similar elements bear identical references. DETAILED DESCRIPTION OF THE INVENTION

[0016] As described above, a turbomachine 1 of an aircraft 100 typically comprises, from upstream to downstream in the direction of gas flow, a fan 2, a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine, a low-pressure turbine, and an exhaust casing 8 extending generally around a longitudinal axis X and located in a primary flow of the turbomachine 1. An example of a turbomachine 1 that may include an exhaust casing according to the invention is a USF-type engine. However, the invention is not limited to this type of engine and is applicable to any turbomachine comprising an exhaust casing.

[0017] Thus, it was represented at the figure 1An example of a hybrid aircraft turbomachine 1 may include an exhaust casing according to an embodiment of the invention. Like known prior art turbomachines, the turbomachine 1 is a twin-flow turbomachine comprising, from upstream to downstream, a fan 2, a low-pressure compressor 3a (also called a booster), a high-pressure compressor 3b, a combustion chamber, a high-pressure turbine 5a, and a low-pressure turbine 5b. Downstream of the low-pressure turbine 5b is arranged an exhaust casing 8. At the downstream end of this exhaust casing, and coaxially therewith, is fixed a nozzle cone, which is an aerodynamic element also called a plug and which guides the exhaust gases exiting the turbomachine 1.The low-pressure compressor 3a and high-pressure compressor 3b, the combustion chamber, the high-pressure turbine 5a, and the low-pressure turbine 5b define a gas stream through which a primary flow P flows. Around these elements, the turbomachine 1 is also traversed by a secondary flow S driven by the fan 2. The primary flow P and secondary flow S converge at the outlet of the turbomachine 1. The high-pressure compressor 3b and the high-pressure turbine 5a are connected by a high-pressure shaft 4b and form a high-pressure unit. The low-pressure compressor 3a and the low-pressure turbine 5b are connected by a low-pressure shaft 4a and form a low-pressure unit.The low-pressure shaft 4a drives the fan 2 via a reduction gear 6 which is arranged substantially in a front casing of the turbomachine 1, also called the inlet casing, in line with fixed outlet guide vanes which straighten the secondary flow S downstream of the fan 2. The turbomachine 1 has several casings, namely, as already seen, the front casing or inlet casing which supports the fixed outlet guide vanes and the exhaust casing 8. It also has an intermediate casing arranged axially between the low-pressure compressor 3a and the combustion chamber 3b, and a turbine casing arranged axially between the high-pressure turbine 5a and the low-pressure turbine 5b.Such a turbomachine configuration 1 is known by the acronym (UHBR ID, Anglo-Saxon acronym for Ultra High Bypass Ratio, Integral Drive), which refers to twin-flow engine configurations comprising a high-pressure body and a low-pressure body which in turn drives a shrouded fan with a very high bypass ratio.

[0018] In one embodiment, the turbomachine 1 is a hybrid turbomachine, meaning that it includes an electric machine 7 coupled to the low-pressure shaft. The hybrid turbomachine 1 architecture according to the invention more particularly comprises an electric machine 7 (which may include an electric generator or an electric motor) arranged downstream of the low-pressure turbine 5b and the exhaust casing 8, coaxially with it along the principal axis X, and housed in the plug inside a nozzle of the turbomachine 1. For its electrical supply, it is necessary that at least one power transmission conductor (electrical harness) cross the duct, in order to ensure the electrical connection of the electric machine 7 with at least one component external to the duct, and in particular with the turbomachine 1.The invention makes it possible to ensure the routing of this power transmission conductive element by advantageously using the exhaust casing 8.

[0019] In this application, upstream and downstream are defined with respect to the normal gas flow direction in the turbomachine 1, and more specifically within the TRF casing 8. The axial direction corresponds to the direction of the X-axis, and a radial direction is a direction perpendicular to and passing through this X-axis. Unless otherwise specified, internal (respectively, inside) and external (respectively, outside) are used with reference to a radial direction such that the inner part or face of an element is closer to the X-axis than the outer part or face of the same element.

[0020] The exhaust casing 8 includes an internal hub 9 coaxial with the longitudinal axis X, an external ferrule 10 coaxial with the internal hub 9 and extending around the internal hub 9 a set of arms 11 mechanically linking the internal hub 9 and the external ferrule 10.

[0021] The arms 11 are regularly distributed circumferentially around the inner hub 9. In one embodiment, the arms 11 extend substantially radially between the inner hub 9 and the outer ferrule 10 of the housing 8. The arms 11 may in particular be slightly inclined (by about 15°) along the circumferential direction.

[0022] Each arm 11 comprises a wall 12 which delimits an internal space extending radially from the internal hub 9 to the ferrule 10, along the entire length of the corresponding arm 11. The arms 11 are therefore hollow.

[0023] The housing 8 further includes electrical control or power harnesses 13 configured to connect electrical equipment 14 (typically, a controller and an electric generator) arranged radially outside the outer shell 10 with electrical equipment 15 (typically, an electric machine such as machine 7) arranged radially inside the inner hub 9, and one or more sleeves 16 extending within an arm 11 at a distance from the wall 12 of the arm 11. The sleeve(s) 16 are connected to the inner hub 9 and to the outer shell 10 by means of mechanical links. Each sleeve 16 includes an inner face 17 defining an internal cavity configured to receive one or more electrical harnesses 13. It should be noted that only one of the arms 11 of the housing 8 can include such a sleeve 16. Alternatively, several or each of the arms 11 of the housing 8 can include a sleeve 16.

[0024] To protect the electrical harnesses 13 from the thermal and vibrational environment of the housing 8 within a limited space, the housing 8 further includes a spacer 18 mounted in each sleeve 16. The spacer 18 is configured to keep the electrical harnesses 13 away from an inner face 17 of the corresponding sleeve 16. For this purpose, the spacer 18 may include a through-hole 19 for the electrical harness 13. In particular, each through-hole 19 is configured to receive a corresponding electrical harness 13. Preferably, the size of the through-hole 19 is adjusted according to the diameter of the corresponding electrical harness 13 so that the spacer 18 can hold the electrical harness 13 securely (without play). Alternatively, the spacer 18 can be mounted to ensure sliding centering within the sleeve 16.

[0025] The spacer 18 prevents contact between the electrical harnesses 13 and the sleeve 16, thereby limiting wear on the electrical harnesses 13 by maintaining a constant air gap between them. The spacer 18 also prevents thermal conduction between the sleeve 16 (which is housed in an arm 11 positioned in a hot gas flow at the turbine outlet) and the electrical harnesses 13, which themselves generate heat (particularly when under high electrical load). Furthermore, the spacer 18 allows for control of the dynamic modes of the electrical harnesses 13.

[0026] In a first embodiment, the housing 8 includes at least two electrical harnesses 13 (for example three) which are housed in the same sleeve 16. A spacer 18 is then mounted in the sleeve 16 so as to keep each electrical harness 13 away from the inner face 17 of the sleeve 16. The spacer 18 is further configured to maintain an air gap between the electrical harnesses 13 housed in this sleeve 16 in order to guarantee the thermal and / or electrical specifications of the harnesses.

[0027] To this end, in one embodiment, each wedge 18 comprises as many through-holes 19 as there are electrical harnesses 13, each through-hole 19 being configured to receive and be traversed by a corresponding electrical harness 13. The through-holes 19 are preferably non-communicating, and in all cases configured so that the wedge 18 provides physical separation between the electrical harnesses 13 within the sleeve 16. For example, when the sleeve 16 houses exactly two electrical harnesses 13, the wedge 18 may comprise two separate through-holes 19.

[0028] The through passages 19 can, for example, be circular or ovoid.

[0029] In a second embodiment, the housing 8 comprises two (or more) electrical harnesses 13, each housed in a corresponding portion of a sheath 16 within the internal cavity of the arm 11. The sheath 16 housed in the arm 11 then comprises as many sheath portions as there are electrical harnesses 13 to be passed along the arm 11 between the outer ferrule 10 and the inner hub 9. Each electrical harness 13 thus passes through a portion of the corresponding sheath 16. A spacer 18 is then mounted in each portion of the sheath 16 so as to keep the corresponding electrical harness 13 at a distance from the inner face 17 of the corresponding portion of the sheath 16. The portions of the sheath 16 are further fixed together to ensure their mechanical stability and to limit their deformation under load, for example by bonding or with the aid of a mechanical separator. The through passage 19 may, for example, be circular or ovoid.

[0030] In this embodiment, each portion of the sheath forms a closed envelope around the electrical harness(es) it receives. The portions of the sheath 16 are also arranged end-to-end along the electrical harnesses 13 so as to form the sheath 16 together.

[0031] The first and second embodiments can of course be combined. Thus, the arm 11 can comprise several sleeves 16, each sleeve 16 housing at least one electrical harness 13 and a spacer 18 separating the corresponding electrical harness 13 from the inner face 17 of the sleeve 16 and, where applicable, from another electrical harness 13 housed in the same sleeve 16. The sleeves 16 are further fixed together as described above.

[0032] Each wedge 18 can be mounted on the electrical harness(es) 13 and / or on the inner face 17 of the corresponding sleeve 16.

[0033] In a first embodiment, the wedge 18 is integrated directly into the outer layers of the electrical harnesses 13 which it receives and is monolithic with these electrical harnesses 13. Alternatively, the wedge 18 can be added and fixed, for example by gluing, onto the electrical harnesses 13.

[0034] In a second embodiment, the wedge 18 is fixed to the inner face 17 of the sleeve 16, for example by gluing.

[0035] The wedge 18 can be movable in translation relative to the electrical harnesses 13 or the sheath 16 in order to take into account in particular the thermal expansion of the sheath 16 and / or the arm 11. In this case, the wedge 18 is fixed only on the electrical harnesses 13 or on the sheath 16. Alternatively, the wedge 18 can be fixed on both the harness and the sheath 16.

[0036] Where appropriate, each sleeve 16 may include several shims 18 distributed along the sleeve 16 between the outer ferrule 10 and the inner hub 9.

[0037] The sleeve 16 can have any suitable shape. Preferably, the sleeve 16 has any suitable cylindrical shape (oval, oblong, rhombus, etc.). For example, the sleeve 16 is cylindrical of revolution. It can be hydroformed and / or welded. The sleeve 16 can be made of any suitable material, for example, stainless steel or a ceramic matrix composite material.

[0038] The wedge 18 can be made of the same material as the sleeve 16.

[0039] Each sleeve 16 is further thermally insulated to protect the electrical harnesses 13 from the high temperatures experienced by the arm 11 of the housing 8. For this purpose, the sleeve 16 can be conventionally insulated using thermal insulators typically used for oil passages in exhaust housings 8s. The thermal insulators can, for example, consist of glass wool or silica and be attached to half-shells mounted on the outer face of the sleeve 16 or slipped over the outer face of the sleeve 16 like a sock.

[0040] The spacer 18 includes bearing areas 20 configured to contact the inner face 17 of the sleeve 16 and provide the air gap between the electrical harnesses 13 and the sleeve 16. In particular, the spacer 18 may include a plurality of discrete bearing areas 20 distributed around its circumference. The bearing areas 20 are separated in pairs by notches that reduce the mass of the bushings and, as we will see later, allow the circulation of a cooling fluid between the spacer 18 and the sleeve 16.

[0041] For example, the slip 18 may include four support zones 20 distributed equidistantly along its circumference. When the slip 18 receives several electrical harnesses 13, the slip 18 includes at least twice as many support zones 20 as it houses electrical harnesses 13, preferably three times as many support zones 20. Thus, when the slip 18 includes two through passages 19, each receiving a corresponding electrical harness 13, it includes at least six support zones 20 facing each other in pairs to ensure a balanced distribution of contacts.

[0042] When the wedge 18 is fixed on the electrical harnesses 13 and in order to limit friction between the wedge 18 and the sleeve 16, the bearing areas 20 can be substantially flat and shaped so as to have a length at most equal to half the radius R of the through passage 19 formed in the wedge 18. Alternatively, the bearing areas 20 can be curved.

[0043] The housing 8 further includes a ventilation system 21 configured to cool the electrical harnesses 13 in order to remove the heat generated by the electrical harnesses 13 when they are under heavy load and to protect the electrical harnesses 13 from the high temperatures that can be reached during operation within the housing 8. The ventilation system 21 can in particular be arranged radially outside the outer shell 10 and be fluidly connected to the sleeve 16 by means of suitable ducts.

[0044] In one embodiment, the cooling fluid F (air) circulating in the sleeve 16 is also used to cool electrical equipment 15 arranged radially inside the inner hub 9, for example, an electrical machine housed in an enclosure within the inner hub 9. For this purpose, the sleeve 16 is mechanically connected to the enclosure to establish fluid communication between the cavity defined by the enclosure and housing the electrical equipment 15 and the ventilation system 21. The sleeve 16 may, for example, include a portion 16a extending within the inner hub 9 that is mechanically connected to the enclosure. The sleeve 16 then extends within the arm 11, from the outer ferrule 10 to the inner hub 9, as well as within the inner hub 9 itself. The portion 16b housed within the arm 11 may be substantially straight.The portion 16a of the sleeve 16 housed in the internal hub 9 can be curved according to the position of the enclosure in order to connect the sleeve 16 to the enclosure. In one embodiment, the internal radial end of the sleeve 16 may include a plate 27 to allow its mechanical connection to the enclosure by means of suitable fasteners, for example, bolts. If necessary, the enclosure and / or the plate 27 may include a series of oblong holes configured to receive the bolts in order to accommodate the geometric tolerances of the arm 11 (greater than one millimeter).

[0045] The sleeve 16 can be mounted on the outer ferrule 10 via a sliding joint 28, allowing radial movement of the sleeve 16 relative to the outer ferrule 10. In this way, the sleeve 16 can slide radially relative to the arm 11 to accommodate differential thermal expansion between the relatively cool sleeve 16 (containing the electrical harnesses 13 and the cooling ventilation for the harnesses and, where applicable, the electrical equipment) and the housing 8, which is heated by the primary flow at the turbine outlet. The sliding joint 28 may, for example, include an intermediate piece that attaches to a boss on the outer ferrule 10 of the housing 8, at the outlet of the arm 11.

[0046] The sleeve 16 can also be mounted on the internal hub 9 via a sliding link 28 so as to allow radial movement of the sleeve 16 relative to the internal hub 9. This radial sliding in the internal part of the sleeve 16 makes it possible in particular to adjust and maintain in operation the play between the sleeve 16 and the arm 11 and avoid any contact between sleeve 16 and arm 11, but also to limit the dynamic modes of the sleeve 16.

[0047] Furthermore, as previously stated, the wedge 18 includes one or more notches 29a, 29b allowing the passage of the cooling fluid F sent by the ventilation system 21 between the wedge 18 and the sleeve 16. Preferably, the wedge 18 includes a notch 29a, 29b between each support area.

[0048] In the embodiment illustrated in the figures, the wedge 18 is substantially flat and comprises two lobes connected by a central bridge, each lobe including a circular through-hole 29. The outer edges of each lobe are substantially circular and coaxial with the corresponding through-hole 29. Here, the wedge 18 is symmetrical with respect to a plane passing through the central bridge. This is not, however, a limiting factor, as the electrical harnesses 13 received by the wedge 18 may have different dimensions, so that the diameters of the through-holes 19 could be different within the wedge 18.

[0049] The wedge 18 comprises six support zones 20, three of which are equally distributed around each lobe and formed, for example, by protrusions projecting in the plane from the outer north of the lobes. Of course, the wedge 18 could include a greater number of support zones 20. In this example, two of the support zones 20 of the wedge 18 are located at the outermost ends of the wedge 18, with the other four support zones 20 placed in pairs at approximately 90° angles to the outermost support zones 20. Two concave notches 29a are formed in the wedge 18 between the two pairs of support zones 20 which surround the central bridge, and four convex notches 29b (delimited by the circular outer edges of the lobes) are formed in the wedge 18 between the pairs of support zones 20 which surround the lobes.It will be understood that the shape of the notches 29a, 29b is not limiting, the wedge 18 may include, for example, only the concave notches 29a or only the convex notches 29b.

Claims

1. A casing (8) for a turbomachine (1), for example an exhaust casing, comprising: - an internal hub (9) extending around an axis (X); - an external flange (10) coaxial with the internal hub (9) ; - a plurality of arms (11) extending from the internal hub (9) to the external flange (10), each arm (11) having a wall (12); - wire harnesses (13) configured to connect a first electrical apparatus (14) which is arranged radially outside the external flange (10) and a second electrical apparatus (15) arranged radially inside the internal hub (9); and - a sheath (16) extending within an arm (11) at a distance from the wall (12) of the arm (11), the sheath (16) comprising an internal face (17) defining an internal cavity configured to receive the wire harnesses (13) ; the casing (8) comprises at least one shim (18) mounted in the sheath (16), each shim (18) being configured to hold the wire harnesses (13) at a distance from an internal face (17) of the sheath (16), and characterized in that the sheath (16) houses at least two wire harnesses (13), the shim (18) also being configured to hold the at least two wire harnesses (13) at a distance from one another within the sheath (16).

2. The casing (8) according to claim 1, wherein the shim (18) comprises at least two through passages (19), each wire harness (13) being housed in a corresponding through passage (19).

3. The casing (8) according to one of claims 1 and 2, further comprising a ventilation system (21) in fluid communication with the internal cavity of the sheath (16).

4. The casing (8) according to claim 3, further comprising a second electrical apparatus (15) arranged radially inside the internal hub (9), the sheath (16) also extending between the internal hub (9) and the second electrical apparatus (15) so that the ventilation system (21) is in fluid communication with the second electrical apparatus (15).

5. The casing (8) according to one of claims 3 and 4, wherein the shim (18) also comprises at least one indentation (29a, 29b) configured to allow circulation of fluid between the external flange (10) and the internal hub (9) in order to place the second electrical apparatus (15) in fluid communication with the ventilation system (21).

6. The casing (8) according to one of claims 1 to 5, also comprising a thermal insulator attached to an external face of the sheath (16).

7. The casing (8) according to one of claims 1 to 6, wherein the sheath (16) is movably mounted relative to at least one of the external flange (10) and the internal hub (9) by allowing radial travel of the sheath (16) relative to the external flange (10) and / or relative to the internal hub (9).

8. The casing (8) according to one of claims 1 to 7, wherein the shim (18) has support zones (20) configured to come into contact with the internal face (17) of the sheath (16) in order to hold the wire harnesses (13) at a distance from the internal face (17) of the sheath (16), the support zones (20) being able to be curved or flat.

9. The casing (8) according to one of claims 1 to 8, comprising at least two wire harnesses (13) and at least two sheath portions forming a sheath (16) which extends within the arm (11), the at least two sheath portions being arranged end-to-end along the wire harnesses (13) so as to form a sheath (16) which surrounds the wire harnesses (13).

10. A turbomachine (1) comprising a casing (8) according to one of claims 1 to 9, the casing being located in a primary stream of the turbomachine (1).