WO2025061698A1 - Low-pressure compressor casing for an aircraft turbine engine - Google Patents

Abstract

The invention relates to a stator assembly of an aircraft turbine engine comprising: • ■ a low-pressure compressor casing, the casing (1) comprising an annular wall (4) extending along a longitudinal axis of the casing; • ■ at least one blade (28) and fastening elements (38) for fastening the blade (28) to the annular wall (4), wherein the blade (28) is formed of composite material and has at least one non-threaded cavity (40), and wherein the stator assembly is configured so that a passage of the fastening elements (38) through the one or more cavities (40) is radially offset with respect to a longitudinal axis (Y) of the blade (28).

Description

DESCRIPTION

TITLE: Low pressure compressor casing of an aircraft turbomachine

[0001] The invention relates to a low-pressure compressor casing for an aircraft turbomachine. It also relates to such a compressor and such a turbomachine. Although particularly intended for fast low-pressure compressors, it is not limited to such use.

[0002] In the field of low-pressure compressors for aircraft turbomachines, it is known to use metal stator blades. These have disadvantages in terms of weight and cost as well as thermal expansion. There is therefore a need for blades that do not have such disadvantages. Various constraints must also be taken into account, in particular in terms of the methods of fixing the blade to its support as well as the orientation of the blade in the air flow.

[0003] The invention aims to at least partially overcome the above drawbacks and to this end proposes a stator assembly for an aircraft turbomachine comprising:

• a low pressure compressor casing, said casing (1) comprising an annular wall (4) extending along a longitudinal axis of said casing,

• at least one blade (28) and fixing elements (38) for said blade (28) on said annular wall (4), said blade (28) being formed from a metal matrix composite material and having at least one non-threaded housing (40), said stator assembly being configured so that a passage of the fixing elements (38) in the housing(s) (40) is radially offset relative to a longitudinal axis (Y) of the blade (28).

[0004] Thanks to the material chosen, namely a metal matrix composite material, the blade is lighter and less subject to thermal expansion. In addition, the non-threaded housing made in the blade allows its fixing while being compatible with such a choice of material. It should also be noted that the fixing elements, for their number and their positioning, at a distance from the center of the blade, allow angular adjustment of the blade.

[0005] According to various additional characteristics of the invention, which may be taken together or separately and which form as many embodiments of the invention:

- there are two of said fixing elements,

- said housings define openings for the passage of the fixing elements through the blade,

- said blade comprises at least one insert, located in said housing, said insert having threaded orifices,

- said composite material of the blade comprises a metal matrix, said metal matrix being formed of aluminum,

- said blade comprises a foot having said housing(s),

- said fixing elements bear on the one hand against an external face of said annular wall and on the other hand against an internal face of said foot,

- said fixing elements comprise bolts and/or rivets.

- the said blade foot is hollowed out,

- said annular wall is an internal wall of the casing,

- said annular wall has a first annular zone and a second annular zone,

- said first zone is intended to be located at the right of a rotor stage of said compressor,

- said second zone is intended to be located at the right of a stator stage of said compressor,

- said blade(s) are located at said second zone,

- said annular wall is formed of metal,

- said annular wall comprises a support ferrule, extending along said first and second zones,

- said support ferrule is made of composite material,

- said annular wall comprises a reinforcing coating, located on an internal wall of said shell at the level of said first zone, - said blade(s) and said reinforcing coating are in abutment against each other, in particular via said blade root,

- said reinforcing coating comprises a metallic lamination material, applied to the internal face of said ferrule,

- said metal lamination material comprises at least two layers of metal and at least two layers of composite material, the layers of metal alternating with the layers of composite material,

- an inner layer of said lamination is formed from one of the metal layers,

- said reinforcing coating comprises a layer of abradable material,

- said layer of abradable material is applied to the internal layer of the metal lamination material,

- said reinforcing coating comprises cartridges following one another angularly over 360° around said longitudinal axis of the casing,

- said cartridges are formed in said reinforcing material,

- said composite material of the ferrule and/or of the metal lamination material is of organic matrix,

- said first zone is intended to be flush with a clearance near a distal edge of blades of the rotor stage of the compressor, said blades of the rotor stage being made of metal,

- said first zone is located at an upstream part of the casing according to the direction of flow of the fluid,

- said second zone is intended to be located at a downstream part of the casing according to the direction of flow of the fluid,

- said second zone is intended to delimit a vein for a divergent flow of said fluid,

- a first longitudinal end of the casing is intended to be secured to a first support,

- a second longitudinal end of the casing, opposite the first end, is intended to be secured to a second support,

- said casing comprises at least one fixing flange, in particular to said first support and/or to said second support, - said casing has an annular part made of composite material, said annular part being provided with a body and a lateral flank connected to said body by an elbow,

- said fixing flange comprises a first part configured to reinforce said annular part of the casing at said elbow and a second part configured to center said annular part on a support.

[0006] The invention also relates to a low-pressure compressor, possibly fast, for an aircraft turbomachine comprising a stator assembly as described above.

[0007] The invention also relates to an aircraft turbomachine comprising a compressor as described above.

[0008] According to one embodiment of the invention, said turbomachine comprises a fan and a speed reducer between said fan and said compressor.

[0009] The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly during the detailed explanatory description which follows, of at least one embodiment of the invention given by way of purely illustrative and non-limiting example, with reference to the appended schematic drawings among which:

[0010] [Fig 1] schematically illustrates a section along a longitudinal cutting plane of an example of a stator assembly according to a first aspect of the invention;

[0011] [Figs. 2a and 2b] schematically illustrate a section along a longitudinal cutting plane of examples of a casing of a stator assembly according to a second aspect of the invention;

[0012] [Fig 3] details a part marked III in figures 2a and 2b;

[0013] [Fig 4] schematically illustrates a section along a longitudinal cutting plane of a part of an example of a casing of a stator assembly according to a third aspect of the invention; [0014] [Fig. 5] schematically illustrates a section along a longitudinal sectional plane of an example of a fixing flange according to a fourth aspect of the invention. [0015] [Fig. 6] schematically illustrates a section along a longitudinal sectional plane of an example of a part of a turbomachine comprising a casing according to the invention.

[0016] As illustrated in Figures 1, 2a and 2b, the invention firstly relates to a stator assembly of a low-pressure compressor, preferably a fast one, of an aircraft turbomachine. Said compressor and said turbomachine are intended to be traversed by a fluid, in particular an air flow, illustrated by the arrow marked 2.

[0017] The stator assembly comprises a casing 1. The casing 1 preferably has a shape of revolution around a longitudinal axis extending in a direction marked X. In the context of the present application, said longitudinal axis is also designated ‘longitudinal axis of the casing’ or ‘longitudinal axis X’. The casing comprises an annular wall 4, in particular an internal wall, extending along the longitudinal axis of said casing 1. In these figures, only a part of the section of the casing 1 has been illustrated, the diametrically opposite part not having been, nor has a possible external wall of said casing.

[0018] The annular wall 4, or a portion of the annular wall 4, may further extend radially around the longitudinal axis of the casing. For example, an inner radius of the annular wall 4 varies as a function of a position along the longitudinal axis. Alternatively, the inner radius of the annular wall 4, or a portion of the annular wall 4, is constant as a function of the position along the longitudinal axis. The inner radius of the annular wall 4 is measured from, and radially relative to, the longitudinal axis of the casing.

[0019] A first longitudinal end of the casing 1 is intended to be fixed to a first support, in particular annular, of the compressor. A second longitudinal end of the casing 1, opposite the first end, is intended to be fixed to a second support, in particular annular, of the compressor.

[0020] Said casing 1 optionally comprises other annular portions, attached to said annular wall 4 and extending it upstream and/or downstream depending on the direction of circulation of the air flow. [0021] In Figure 1, the parts marked 4', 4”, partially illustrated, alternately represent said first support and/or said second support of the compressor allowing the fixing of the casing 1 and/or the parts of the casing 1 extending upstream and/or downstream of said annular wall 4.

[0022] Said annular wall 4 has a first annular zone 6 and a second annular zone 8. Said first zone 6 is intended to be located in line with a rotor stage 10 of said compressor. Said rotor stage 10 here has one or more blades 11 and said first zone 6 of the casing 1 is located at the level of said blades 11. Said second zone 8 is intended to be located in line with a stator stage 12 of said compressor.

[0023] Said first zone 6 is located, for example, at an upstream part of the casing 1 in the direction of flow of the fluid. Said second zone 8 is located, for example, at a downstream part of the casing 1 in the direction of flow of the fluid. Said first zone 6 and said second zone 8 are advantageously located in a longitudinal extension of one another.

[0024] As illustrated in Figure 6, said first zone 6 is located, for example, upstream of a separation nozzle 80 of the flows of the turbomachine according to the direction of flow of the fluid. Said second zone 8 is located, for example, downstream of a separation nozzle 80 of the flows of the turbomachine according to the direction of flow of the fluid.

[0025] Said first zone 6 is located, for example, at the level of the upstream vein 83 of the low pressure compressor. Said second zone 8 is located, for example, at the level of the radially external downstream vein 81 of the low pressure compressor.

[0026] Preferably, said first zone 6 has a better retention capacity than said second zone 8. This is all the more necessary in a fast low-pressure compressor in which the potentially generated debris has a greater speed and therefore greater energy.

[0027] Preferably, said second zone 8 is intended to delimit a vein for a divergent flow of said fluid. By "divergent" is meant that a main direction of said flow deviates radially from said longitudinal axis of the casing according to the direction of circulation of said flow. Alternatively or cumulatively, said stator assembly comprises stator blades 28 fixed to the casing 1, in particular bolted, to said second zone 8, for example as will be described later.

[0028] Preferably, an inner radius of the annular wall 4 is substantially constant at the level of said first zone 6 intended to be located at right angles to a rotor stage 10 of said compressor. In other words, the annular wall 4 at the level of said first zone 6 preferably extends mainly in the longitudinal direction. Preferably, the inner radius of the annular wall 4 at the level of said second zone 8 is increasing, preferably strictly increasing, according to the direction of circulation of the flow. In other words, the annular wall 4 at the level of said second zone 8 preferably deviates radially from said longitudinal axis according to the direction of circulation of said flow, that is to say from upstream to downstream of the annular wall. The inner radius of the annular wall 4 is measured from the longitudinal axis of the casing, and in the radial direction relative to the longitudinal axis of the casing.

[0029] Preferably, said turbomachine comprises a flow separation nozzle 80. An example of such a nozzle 80 is shown in FIG. 6. Said nozzle 80 is configured to separate the air flow passing through the turbomachine into two radially internal and external flows, respectively. In FIG. 6, the flow directions of the air flows are represented by the arrows 2.

[0030] At the nozzle 80, an upstream flow path 83 of the turbomachine divides into a radially external downstream flow path 81 and a radially internal downstream flow path 82. In this way, the air flow upstream of the nozzle is divided, i.e. separated, into two separate air flows downstream of the nozzle.

[0031] The spout separates a radially external vein 81 for the passage of fluid from a radially internal vein 82 for the passage of fluid. Preferably, said radially internal and/or external vein is annular around the longitudinal axis X. The radially internal vein is closer to the longitudinal axis than the radially external vein. Preferably, the spout 80 extends circumferentially around the longitudinal axis.

[0032] Preferably, said first zone 6 and said second zone 8 are positioned on either side of the spout 80 in the longitudinal direction X. Said first zone is upstream of the spout. Said second zone 8 is downstream of the spout. Said second zone 8 is intended to delimit the radially external annular vein, preferably for a divergent flow of said fluid.

[0033] According to a first aspect of the invention corresponding to figure 1, said first zone 6 and said second zone 8 are respectively formed of a first section 7 and a second section 9, distinct from one another. This means that said first and second sections 7, 9 are not in continuity of material with one another. On the contrary, they are advantageously attached to one another, directly or indirectly. Said first section preferably comprises a metallic material, said second section preferably being made of composite material.

[0034] Preferably, said first section and said second section are upstream and downstream, respectively, according to the direction of circulation of the fluid in the turbomachine.

[0035] Thanks to the sections respectively forming the zones 6, 8 of the casing according to this first aspect of the invention, said first and second zones 6, 8 of the casing are independent of one another. They can thus be formed from one or more materials ensuring the function specific to them instead of having recourse to a single-piece casing made of a single material, possibly heavier and/or more expensive, and risking not fulfilling the specifications of all the zones as well as possible.

[0036] Preferably, the inner radius of the annular wall 4 is substantially constant at the first section 7 (or the first zone 6) and the annular wall 4 deviates radially from said longitudinal axis at the second section 9 (or the second zone 10). In this configuration, it is possible to take advantage of the two sections to separate the part of the casing extending mainly in the longitudinal direction from the part of the casing which is divergent according to the direction of circulation of said flow. This facilitates the manufacture and assembly of the casing.

[0037] The positioning of the junction between the first and second sections is preferably carried out in an area without a function of retention or fixing of the stator. The positioning of the junction between the first and second sections is for example carried out at the level of the beak 80 in the longitudinal direction X.

[0038] To ensure the retention function which is advantageously conferred on it, said first section 7 preferably comprises a metallic material, in particular a block of metallic material such as aluminum, an aluminum alloy, titanium and/or a titanium alloy. Alternatively, it is a metal lamination which will be described in more detail below in relation to a second aspect of the invention.

[0039] Said first section 7 comprises, for example, cartridges forming angular sectors following one another over 360° around said longitudinal axis of the casing 1.

According to a first embodiment, said first section 7 is, for example, continuous and formed from the same block of material, in particular the same block of metallic material and/or the same metallic lamination, over its entire circumference and its thickness.

[0040] Alternatively, said first section 7 is formed from said block of metallic material and/or said metallic lamination, taken in the form of cartridges as mentioned above. In such a case, said cartridges are advantageously subject to said second section 9.

[0041] Alternatively, said first section 7 comprises a support shell. It further comprises a reinforcing coating comprising said metal lamination material, said reinforcing coating then being attached to an inner face of said shell, for example continuously over its entire circumference or in the form of cartridges as mentioned above. Said shell is formed, in particular, from a composite material. Such a configuration of the first section is described below in the context of the second aspect of the invention in which the support shell 14 is continuous over all of the first and second zones 6, 8 but has a first zone 6 having the configuration with support layer 14 and reinforcing coating 32 in question. In the context of the first aspect of the invention, according to the alternative mentioned, the first section 7 is attached to the second section 9 via said support shell.

[0042] Preferably, the reinforcing coating 32 is received in a recess of the support ferrule 14. An example is illustrated in FIG. 2b. The reinforcing coating comprises an internal surface, i.e. radially internal relative to the longitudinal axis X. The support ferrule comprises an internal surface, i.e. radially internal relative to the longitudinal axis X. For example, the inner surface of the annular wall 4 located at the first zone comprises, or is formed by, the inner surfaces of the reinforcing coating and the support shell. For example, the inner surfaces of the reinforcing coating and the shell successively and in this order form the inner surface of the annular wall in the direction of flow of the fluid within the casing. In the example illustrated in Figure 2b, the inner surface of the shell, then the inner surface of the reinforcing coating, then the inner surface of the shell, successively form in the longitudinal direction and in this order, the inner surface of the annular wall. For example, the inner surfaces of the reinforcing coating and the shell delimit a fluid circulation vein at the first zone 6.

[0043] Preferably, at the interface between the inner surfaces of the reinforcing coating and the support ferrule, these are aligned in continuity with each other. Such continuity of the wall improves the flow of the fluid. Preferably, at the interface between the inner surfaces of the reinforcing coating and the support ferrule, these have radii measured radially from the longitudinal axis X which are identical. Preferably, such a radius is substantially constant in the first zone 6.

[0044] According to some of the alternatives mentioned above, it will be understood that said cartridges are possibly formed with said metal lamination material.

[0045] Said first zone 6 is intended to be flush with a clearance near a distal edge 30 of the blade(s) 11 of the rotor stage 10 of the compressor. Said blades 11 of the rotor stage 10 are advantageously made of metal. In this way, the metallic configuration of the first zone 6 of the casing and of the blade(s) 11 of the rotor stage makes it possible to limit differential thermal expansion between the casing 1 and said blade(s) 11.

[0046] Said second section 9 is advantageously made of composite material. This avoids having to produce an all-metal casing, which is expensive and heavy. Said composite material is, for example, an organic matrix. It is in particular a material comprising an epoxy matrix and/or carbon fibers, advantageously unidirectional. It is optionally draped, in particular by robot. [0047] As already indicated, said first section 7 and said second section 9 are advantageously secured to each other, in particular without intermediate sections.

[0048] Said first section 7 advantageously comprises a centering shoulder 24 for said second section 9. For example, said second section 9 bears on said shoulder 24 by an inner face 26 or outer face of said second section 9. Preferably, said second section 9 bears on said shoulder 24 by an inner face 26 of said second section 9. In the case where the first section 7 is metallic and the second section 9 is formed of a composite material, the metal expanding more than the composite with an increase in temperature, using the inner surface of the part made of composite material to ensure the support makes it possible to maintain contact and therefore centering when the temperature increases.

[0049] Said casing 1 here further comprises attachment flanges 16, 18, 20, 22, preferably circumferential, in particular originating from one and/or the other of said first and second sections 7, 9. They are intended, for example, for attachment to the other section and/or for attachment to the other parts and/or supports 4', 4" of the casing and/or the compressor. Although this is not illustrated in Figures 1 and 2, the casing 1 optionally further comprises one or more fixing flanges as described below in the context of a fourth aspect of the invention.

[0050] Said shoulder 24 is located here at the level of one of the flanges 18, provided at the level of the first section 7, opposite one of the flanges 20, provided at the level of the second section 9.

[0051] As illustrated in Figures 2a and 2b, according to the second aspect of the invention, said annular wall 4 of the casing 1 comprises a support shell 14, made of composite material, and a reinforcing coating 32 comprising a metal lamination material. Said reinforcing coating is located on the internal face 17 of said shell 14, at the level of said first zone 6.

[0052] Said ferrule 14 thus forms a light and inexpensive base of said annular wall 4. This constitutes a significant advantage compared to an annular wall formed from a metal ferrule. This avoids the use of a rough or block of metal from which a large part of the material would be removed to bring the ferrule back to the desired shape. Such a block of metal can cause supply problems and results in significant material waste.

[0053] Said ferrule 14 is further reinforced only where necessary, i.e. the first zone 6, by the metal lamination material which offers additional retention capacities and makes it possible to better meet the requirements of a fast low-pressure compressor. Indeed, in such a case, if a rotor blade 11 breaks, a reinforced casing is required to retain it given its greater energy.

[0054] According to this aspect of the invention, said support ferrule 14 advantageously extends along said first and second zones 6, 8 of said annular wall 4. Said ferrule 14 thus forms a base common to these two zones 6, 8 which further reinforces the saving of material compared to the use of a raw material or block of metal. It is understood that, in this embodiment, said reinforcing material 32 does not extend along said second zone 8. Indeed, this second zone 8 does not need to be reinforced.

[0055] Said composite support ferrule 14 preferably forms an external layer of the casing 1. In other words, said support ferrule 14 does not have a metal coating on its external face 15.

[0056] As illustrated in Figure 3, said metal lamination material 12 comprises, for example, at least two layers of metal 12a and/or at least two layers of composite material 12b. The layers of metal 12a alternate with the layers of composite material 12b. An inner layer 34 of said metal lamination material 12 is formed from one of the layers of metal 12a.

[0057] Preferably, said reinforcing coating 32 comprises a layer of abradable material 36, attached to the internal face of the metal lamination material 12. Said abradable material is formed, for example, of a material which will be abraded by the rotor blades 11 when the compressor is put into service, in particular during the test phase. In this way, a minimum clearance is achieved between the support coating 32 and said rotor blades 11. The choice of making the internal layer 34 of the metal lamination material 12 from metal makes it possible to facilitate the adhesion of said layer of abradable material 36 to said metal lamination material 12. It should be noted that the reinforcing coating 32 possibly used in the framework of the first aspect of the invention presented above preferentially presents said layer of abradable material 36.

[0058] Said metal lamination material 12 is obtained, for example, by baking. Said baking serves to harden the composite material of its layers 12b. This is sometimes referred to as co-baking. Such baking or co-baking possibly takes place with the support shell 14. In other words, the metal lamination material 12 is baked directly with the support shell 14, which allows them to be fixed to each other.

[0059] According to this second aspect of the invention as according to the first, said reinforcing coating 32, in particular said metal lamination material 12, is optionally formed from cartridges formed from angular sectors succeeding one another over 360° around said longitudinal axis of the casing.

[0060] As explained above in the context of the first aspect of the invention, the reinforcing coating 32 is preferably received in a recess of the support shell 14. An example is illustrated in FIG. 2b. The internal surface of the annular wall 4 located at the first zone is formed by the internal surfaces of the reinforcing coating and of the support shell. For example, the internal surfaces of the reinforcing coating and of the shell successively and in this order form the internal surface of the annular wall according to the direction of flow of the fluid within the casing. In the example illustrated in FIG. 2b, the internal surface of the shell, then the internal surface of the reinforcing coating, then the internal surface of the shell, successively form the internal surface of the annular wall in the longitudinal direction.

[0061] Preferably, at the interface between the inner surfaces of the reinforcing liner and the support ferrule, they are aligned in continuity with each other. Preferably, at the interface between the inner surfaces of the reinforcing liner and the support ferrule, the inner surfaces of the reinforcing liner and the support ferrule are radially aligned. Such wall continuity improves fluid flow.

[0062] At the interface between the inner surfaces of the reinforcing liner and the support ferrule, the inner surfaces of the reinforcing liner and the support ferrule preferably have radii measured radially from the longitudinal axis X which are identical. Preferably, such a radius is substantially constant in the first zone 6.

[0063] Said composite material of the ferrule 14 and/or of the layers 12b of the metal lamination material is, for example, an organic matrix. It is in particular a material comprising an epoxy matrix and/or carbon fibers, advantageously unidirectional. It is optionally draped, in particular by robot, in particular for the case of the ferrule 14.

[0064] Preferably:

• said reinforcing coating delimits a fluid circulation vein at the level of the first zone,

• said support ferrule delimits a fluid circulation vein at the level of the second zone.

[0065] Said annular wall is preferably devoid of reinforcing coating at the level of the second zone. This makes it possible to benefit from the retention performances associated with the reinforcing coating at the level of the first zone of the annular wall while reducing the mass associated with the second zone of the annular wall thanks to the use of composite material.

[0066] The second zone is at least partially, preferably entirely, free of metal lamination material. Preferably, only the first zone is provided with metal lamination material.

[0067] Preferably, said support ferrule is in one piece. This facilitates assembly of the casing.

[0068] Preferably, said support ferrule extends continuously along said first and second zones. Such a ferrule reduces the number of parts to be assembled to form the casing.

[0069] As illustrated in Figure 4, according to a third aspect of the invention, the casing 1 of the stator assembly comprises an annular wall, in particular the annular wall 4 according to the configuration of the first aspect or the second aspect of the invention. The stator assembly comprises at least one blade, in particular the stator blade(s) 28 previously mentioned, and elements 38 for fixing said blade 28 to said annular wall 4. As in Figures 1 and 2, only a part of the casing 1 has been illustrated, the diametrically opposite part not having been, as well as a possible external wall of said casing.

[0070] It should be noted that said casing 1 according to this third aspect of the invention is a low-pressure compressor casing of an aircraft turbomachine but without necessarily being a fast low-pressure compressor casing.

[0071] Said blade 28 is formed from a composite material. Said composite material of the blade 28 comprises, for example, a metal matrix, in particular formed from aluminum.

[0072] Said blade 28 comprises a blade root for mechanically coupling said blade with said annular wall. The root of a blade is sometimes called the 'base' or 'platform' of the blade.

[0073] Said blade 28 comprises a first blade blade delimited by a blade head and the blade root. The blade is fixed on the blade root. The blade extends between the blade root and the blade head along a longitudinal axis of the blade Y.

[0074] The longitudinal axis of the blade Y is different from the longitudinal axis of the casing extending in the direction marked X. Preferably, the longitudinal axis of the blade Y is substantially aligned in the radial direction around the longitudinal axis of the casing. [0075] Said blade 28 has at least one housing 40, which is not threaded. By non-threaded, it is meant that said housing is intended to allow passage but not engagement of a screw or bolt. Its walls are advantageously smooth. Unlike a threaded orifice, said housing can therefore be formed in the thickness of the composite material of the blade 28 without risking damaging and/or weakening it. [0076] The stator assembly is configured so that a passage of the fixing elements 38 in the housing(s) 40 is radially offset relative to a longitudinal axis Y of the stator blade 28.

[0077] The blades 28 are thus lighter due to the choice of the material from which they are made, namely a metal matrix composite material rather than a metal material. Furthermore, since the fixing elements 38 are not in the center of the blade 28, they allow angular adjustment of the blade in the air flow.

[0078] Said fixing elements 38 are advantageously two in number. This makes it possible to limit their number while ensuring a satisfactory connection and the angular setting mentioned above. Here they are diametrically opposed with respect to the longitudinal Y axis of the blade.

[0079] Said blade 28 comprises a root 44. Said root 44 of the blade 28 is optionally hollowed out to further limit the weight of the blade 28. Said root 44 of the blade 28 has said housings 40.

[0080] The platform or foot of the blade extends essentially in the radial direction around the longitudinal axis Y of the blade. Preferably, the foot of the blade comprises an internal face 46 defining a profile of a vein for a flow of fluid. The internal face extends from the blade and essentially radially around the longitudinal axis Y of the blade.

[0081] Preferably, the blade has two housings 40 located on either side of the blade in the longitudinal direction X of the casing.

[0082] Preferably, the blade has two housings 40 located upstream and downstream of the blade according to the direction of flow of the fluid, respectively.

[0083] According to the illustrated embodiment, said housings 40 advantageously define opening orifices 41 for the passage of the fixing elements through the blade 28. Said annular wall 4 has, in particular, slots 42. Said slots 42 are located in an axial extension of said opening orifices 41. The opening orifices preferably pass through the internal face of the root of the blade.

[0084] Said fixing elements 38 bear on the one hand against the external face 15 of said annular wall 4 and on the other hand against the internal face 46 of said foot 44. Said fixing elements 38 comprise, in particular, bolts, as shown. Alternatively, they could be, for example, rivets.

[0085] Preferably, the stator assembly is configured so that, when the blade is mechanically coupled to the annular wall by the fixing elements 38, the setting of the blade 28 is determined by the relative positioning between the housings 40 of the blade and the slots 42 of the annular wall 4 crossed by the fixing elements. This facilitates the assembly of the stator assembly.

[0086] In the advantageous embodiment where the stator assembly comprises two fixing elements 38 and two housings 40 and two slots 42, a segment connecting the centers of the two lights is for example angularly offset relative to the longitudinal axis of the casing X.

[0087] It may be noted that said opening orifices 41 here have a shoulder 41' making it possible to accommodate a head 52 of said bolts so that said head 52 is at least partially, or even entirely, housed in said opening orifices 41.

[0088] As a variant, not shown, said stator blade comprises at least one insert, located in said housing, said insert having one or more threaded orifices allowing the blade to be screwed onto the annular wall of the casing. In this variant, even if screwing is used, the housing or housings formed in the blade remain unthreaded since it is the inserts fitted into said housing or housings which have the threading necessary for screwing.

[0089] According to the illustrated embodiment, said annular wall 4 comprises the support shell 14, made of composite material, and the reinforcing coating 32, mentioned above, in particular in relation to the second aspect of the invention. Said openings 42 are made in said support shell 14, in the second zone 8. The metal lamination material 12 is located on the internal face 17 of said shell 14, at the level of said first zone 6.

[0090] Said blade(s) 28 and said reinforcing coating 32, in particular said metal lamination material 12 and/or said layer of abradable material 36, are preferably in abutment against each other, in particular by means of said root 44 of the blade 28.

[0091] Preferably, the stator assembly is configured so that a downstream portion of the metal lamination material 12 and/or the layer of abradable material 36 is mechanically coupled to the blade and to the annular wall by compression between an upstream portion of the root 44 of the blade and the support shroud 14. The upstream and downstream portions of the parts are determined according to the direction of flow of the fluid in the stator assembly. Said compression is preferably exerted by one or more fixing elements 38.

[0092] In Figure 4, said stop is produced at the level of the layer of abradable material 36. Said metal lamination material 12 has at least one passage 45 crossed by one of said fixing elements 38. [0093] Preferably, a thickness of the root 44 of the blade 28 measured along the longitudinal direction Y of the blade decreases strictly between the downstream and upstream of the root. This makes it possible to compensate for the excess thickness due to the presence of the metal lamination material 12 and/or the layer of abradable material 36 between the upstream portion only of the root and the support shroud. Preferably, the internal face 17 of the support shroud 14 is rectilinear at the root of the blade. The upstream and downstream portions of the parts are determined according to the direction of flow of the fluid in the stator assembly.

[0094] As illustrated in Figure 5, according to its fourth aspect, the invention relates to a fixing flange 50 for a casing, in particular a low-pressure compressor casing, possibly a fast one, of an aircraft turbomachine. As in Figures 1, 2 and 4, only a part of the casing has been illustrated, namely here a connecting part, the diametrically opposite part not having been illustrated, nor a possible external wall of said casing.

[0095] Said casing has an annular part 52, made of composite material. This may be the annular wall 4 of the casing 1 of the previous aspects of the invention, in the corresponding embodiments.

[0096] Said annular part 52 is provided with a body 54 and a lateral flank 56 connected to said body 50 by an elbow 58.

[0097] Said flange 50 comprises a first part 60 configured to reinforce said annular part 52 of the casing 1 at the level of said elbow 58 and a second part 62 configured to center said casing 1 on a support 64.

[0098] According to this aspect of the invention, thanks to said specific parts 60, 62, the fixing flange 50 allows both reinforcement of the casing 1 at the level of an area at risk of delamination, namely the elbow 58, and centering of the casing 1.

[0099] Delamination, or delamination, is generally described as a characteristic failure mode of a material that shears longitudinally in a plane perpendicular to its thickness. This results in disjointed layers, or strata, which eventually separate.

[0100] Said fixing flange 50 is preferably annular. According to a first variant, it is angularly continuous. According to another variant, it is formed of angular portions following one another over 360° around the longitudinal axis of the casing 1.

[0101] Said first part 60 is radially internal and/or said second part 62 is radially external relative to the longitudinal axis of the casing.

[0102] Said first part 60 has a shape intended to fit said elbow 58, in particular inside said elbow 58. It is advantageously formed from an internal edge 66, in particular rounded, of said flange 50.

[0103] Said flange 50 here has an internal face 68 intended to define a stop, said internal face 68 defining said second part 62 of the flange 60. Preferably, said second part 62 achieves the centering of said annular part by contact with a radially external surface of the support 64.

[0104] In the illustrated embodiment, said second part 62 radially covers a free edge 70 of said lateral flank 56. Said flange 50 thus provides protection for said free edge 70, in particular fire protection, which is all the more appropriate in the case of a free edge made of composite material.

[0105] Said flange 50 has, for example, a cross-section in the shape of an L. A large branch of the L has a free edge defining said internal edge 66. A small branch of the L defines said internal face 68 forming a stop.

[0106] Said flange 50 and/or said lateral flank 56 has passage orifices 73, 72 for fixing elements on said support 64. Said support 64 has a bore, possibly threaded, in which said fixing elements are intended to engage. Said fixing elements have not been illustrated in FIG. 4. [0107] Said support 64 is formed, for example, of a hanging flange, in particular one of the hanging flanges 16, 18, 20, 22 mentioned above. Said support 64 is preferably metallic.

[0108] Said fixing flange 50 is formed, for example, of a metallic material, in particular aluminum and/or titanium.

[0109] According to the first and second aspects of the invention, said fixing flange 50 is optionally used between the first zone 6 and the neighboring part 4' when the first zone 6 comprises a support ferrule 14 made of composite material. It is then on the side of the first zone 6. It is also optionally used between the second zone 8 and the neighboring room 4”. It is then on the side of said second zone 8.

[0110] In the first embodiment, it is still possibly used between the first and second sections 7, 9, in particular on the side of the second section 9.

[0111] Although it is not illustrated in its entirety, said low-pressure compressor, preferably fast, of an aircraft turbomachine according to the invention has said rotor stage 10 and said stator stage 12. It further comprises said casing 1 of the previous aspects of the invention.

[0112] As an alternative to the embodiments mentioned above in which the stator blades 28 are secured to the casing 1, said stator blades 28 are in non-immobilizing mechanical contact with the second zone 8. In this new alternative, said stator blades 28 are, for example, attached radially internally to an internal shell of the compressor. Alternatively, said stator blades are attached radially externally to the casing, at the level of the second zone of the compressor casing.

[0113] The aircraft turbomachine according to the invention preferably comprises a fan and a speed reducer between said fan and said compressor. Said reducer allows the low pressure compressor to have a rotation speed faster than a rotation speed of the fan. Said rotation speed of the fan is thus slower and compatible with subsonic air flow.

[0114] Preferably, the casing of the invention is a casing for a fast low-pressure compressor of an aircraft turbomachine. The term 'fast' designates a low-pressure compressor for a turbomachine comprising a fan and a speed reducer between said fan and said compressor. Said reducer allows the low-pressure compressor to have a rotational speed different from and higher than a rotational speed of the fan. The rotational speed of the fan being limited in the case of a subsonic air flow, the rotational speed of a low-pressure compressor in a turbomachine comprising such a reducer can therefore be higher than in a turbomachine not comprising such a reducer. [0115] In such a low-pressure compressor, the retention function of the casing in line with the rotor blades is reinforced. Indeed, the higher rotation speed of the compressor permitted by the presence of the reducer implies a higher kinetic energy of the rotor blades of the compressor during its operation. In the event of breakage and/or detachment of a rotor blade, a reinforced retention capacity is therefore necessary in order to limit the damage caused by the detached blade in the environment of the low-pressure compressor.[0116] According to one embodiment of the invention, said turbomachine comprises:

• a flow separation nozzle,

• an upstream vein,

• a radially internal downstream vein,

• a radially external downstream vein, the nozzle being configured to separate an air flow from the upstream vein into a first air flow passing through the radially internal downstream vein and a second air flow passing through the radially external downstream vein.

[0117] Preferably, said first zone delimits the upstream vein. Preferably, said second zone delimits the radially external downstream vein.

[0118] In such a turbomachine, the first and second zones belong respectively to the upstream vein and to the radially external downstream vein. [0119] In an exemplary embodiment of the invention, the first zone and the second zone are located upstream and downstream of the nozzle, respectively, according to the direction of flow of the air flow. In an exemplary embodiment of the invention, the first zone and the second zone are preferably located upstream and downstream of the nozzle, respectively, according to the longitudinal axis X.

[0120] Preferably, said reinforcing coating delimits the upstream vein. In other words, a radially inner surface of the reinforcing coating belongs to a radially inner surface of the upstream vein. Preferably, said support ferrule delimits the radially outer downstream vein. In other words, a radially inner surface of the radially inner downstream vein comprises a radially inner surface of said support ferrule. [0121] Preferably, said reinforcing coating extends upstream of the nozzle in the direction of flow of the flow in the compressor. Preferably, said reinforcing coating extends only upstream of the nozzle in the direction of flow of the flow in the compressor.

[01 2] The invention considered according to its different aspects comprises different parts each comprising one or more composite materials. The composite materials of the different parts are identical or different. For example, said ferrule is formed from a composite material of said ferrule. For example, said first section is formed from a composite material of the first section and/or has an annular portion made from a composite material of the first section. For example, said second section is formed from a composite material of the second section and/or has an annular portion made from a composite material of the second section. For example, said ferrule is formed from a composite material of said ferrule. For example, said stator blade(s) are formed from a composite stator blade material, preferably from a metal matrix composite material. For example, the metal lamination material comprises the composite material of the layers of the metal lamination material.

[0123] The composite materials forming separate parts of the device of the invention are selected independently from one or more types of composite materials, and may therefore be identical or different from each other.

Claims

1. Stator assembly of an aircraft turbomachine comprising: • a low pressure compressor casing, said casing (1) comprising an annular wall (4) extending along a longitudinal axis of said casing, • at least one blade (28) and fixing elements (38) for said blade (28) on said annular wall (4), said blade (28) being formed from a metal matrix composite material and having at least one non-threaded housing (40), said stator assembly being configured so that a passage of the fixing elements (38) in the housing(s) (40) is radially offset relative to a longitudinal axis (Y) of the blade (28). 2. Stator assembly according to claim 1 wherein said fixing elements (38) are two in number. 3. Stator assembly according to any one of the preceding claims in which said housings (40) define openings for the passage of the fixing elements through the blade. 4. Stator assembly according to any one of the preceding claims wherein said blade (28) comprises at least one insert, located in said housing, said insert having threaded orifices. 5. A stator assembly according to any preceding claim wherein said composite material of the blade (28) comprises a metal matrix. 6. Stator assembly according to any one of the preceding claims in which said blade (28) comprises a foot (44) having said housing(s) (40). 7. Stator assembly according to the preceding claim in which said fixing elements (38) bear on the one hand against an external face (15) of said annular wall (4) and on the other hand against an internal face (46) of said foot (44). 8. Stator assembly according to any one of the claims in which said annular wall (4) has a first annular zone (6) and a second annular zone (8), said first zone (6) being intended to be located in line with a rotor stage (10) of said compressor and said second zone (8) being intended to be located in line with a stator stage (12) of said compressor, said blade(s) (28) being located at the level of said second zone (8). 9. Stator assembly according to the preceding claim wherein said annular wall (4) comprises a support ferrule (14), extending along said first and second zones (6, 8). 10. Stator assembly according to the preceding claim wherein said annular wall (4) comprises a support coating (32), located on an internal wall (17) of said ferrule (14) at the level of said first zone (6). 1 1. Stator assembly according to the preceding claim in which said blade(s) (28) and said support covering (32) are in abutment against each other. 12. Stator assembly according to any one of claims 10 or 11 wherein said reinforcing coating (32) comprises cartridges succeeding each other angularly over 360° around said longitudinal axis of the casing. 13. Compressor, in particular low pressure compressor, possibly fast, for an aircraft turbomachine comprising a stator assembly according to any one of the preceding claims. 14. Aircraft turbomachine comprising a compressor according to the preceding claim. 15. Turbomachine according to the preceding claim comprising a fan and a speed reducer between said fan and said compressor.