CRANKCASE FOR AN AIRCRAFT TURBOMACHINE

Abstract

The invention relates to a fairing housing (200) for a fan blade for an aircraft turbomachine, this housing having an annular shape around a longitudinal axis (A) and having at its axial ends annular fixing flanges (2041, 2042), respectively upstream (2041) and downstream (2042), the housing being made of composite material and comprising a preform made by weaving warp (FC) and weft (FT) yarns, and a polymer matrix in which this preform is embedded, characterized in that, between an intermediate section (202a) and at least one of the flanges, the housing (200) comprises another section (202b) of which at least a part of the warp yarns are made from fibers in a first material of a first stiffness, and the rest of the warp yarns are made from fibers in a second material of a second stiffness greater than that of the first material. Figure for the abbreviation: Figure 3

Description

Title of the invention: Casing for an aircraft turbomachine Technical field of the invention

[0001] The present invention relates to a fairing housing for a fan blade for an aircraft turbomachine and a turbomachine comprising this housing. Technological background

[0002] Generally, a turbomachine 100, in particular an aircraft turbomachine, as illustrated in [Fig.1A], comprises from upstream to downstream (i.e. in the direction of flow of the gas flows F), a blower 110, one or more compressors 102 b 1022, a combustion chamber 104, one or more turbines 106 b 1062 and an ejection nozzle 108 for the combustion gases exiting the turbine(s).

[0003] Figure 1B schematically and partially illustrates a fan 110 of a turbomachine. The fan 110 comprises a fan blade or impeller 112 which is surrounded by a fan housing or shroud 200, also called a retaining housing because of its function of retaining the blades in the event of their breakage, or in the event of debris entering the fan.

[0004] With reference to [Fig. IC], a blower housing 200, and more generally a housing 200, typically comprises an annular casing 202, which may be, for example and without limitation, made of metallic material or of composite material made from woven fibers embedded in a polymer resin. Preferably, the annular casing is made of composite material.

[0005] In a context of reducing the ecological footprint of aircraft, the use of a lightweight but equally efficient material, such as composite material, makes it possible to significantly improve the environmental performance of aircraft by reducing in particular their mass and, at the same time, their fuel consumption.

[0006] With further reference to [Fig. 1C], the annular casing 202 has an axis of revolution A and extends around the turbomachine's fan blades 112. The housing 200 includes an annular mounting flange 204b 2042 at each of the axial ends of the annular casing 202. These flanges 204b 6042 are used to fix the housing 200 to annular walls of a nacelle that surrounds the turbomachine to form an aircraft propulsion assembly.

[0007] The housing 200 can, for example, be connected by flanges 204b 2042 on the one hand to an air inlet sleeve 4a located upstream of the blower housing 200, and on the other hand, to an intermediate housing ferrule located downstream of the blower housing 200. The housing The 600 blower also includes upstream acoustic panels 210, as illustrated in [Fig.1D], and downstream acoustic panels (not shown).

[0008] With reference to [Fig. 1D], an abradable annular cartridge can be positioned on an internal annular surface 300i ([Fig. 1C]) of the casing 202 of the housing 200, between the upstream acoustic panels 210 and the downstream acoustic panels. This abradable cartridge can comprise an annular layer 208 of abradable material and an annular panel or support 206 supporting the annular layer 208, the panel 206 being fixed to the casing 202. This abradable annular layer 208 is designed to wear in a controlled manner during operation. As for the panel 206, it can, for example, be solid or have a honeycomb structure. The housing 200 may further include at least one stiffener 302a fixed to the external surface 3002 of the casing 202 as illustrated, for example, in [Fig. 1E]. The stiffeners contribute to strengthening or improving the rigidity of the housing 200.

[0009] In addition to the retention function, the housing 200 is also designed to: - ensure mechanical continuity (of forces and moments) between the air inlet sleeve and the intermediate housing ferrule; - to allow the fixing of the panels of the abradable annular cartridge, the upstream acoustic panels and the downstream acoustic panels, thus ensuring continuity of the aerodynamic flow; - to allow the attachment of equipment and supports known in themselves, in particular inside the gondola; - to comply with fire and leakage regulations; - to allow continuity of the electrical current for lightning protection, etc.

[0010] The casing 202 of the housing 200 and the annular cartridge are separate parts which are manufactured separately and then assembled in an assembly step in which the panel 206 is first fixed to the annular casing 202 and then the abradable annular layer 208 is glued to the panel 206.

[0011] It has already been proposed to manufacture the blower housing casing from material composite made from woven fibers embedded in a polymer resin, the manufacturing process being of the "RTM" type (English acronym for "Resin Transfer Molding").

[0012] In an RTM manufacturing process, a mold comprising two half-shells, one placed on top of the other, encloses a molding cavity. The fibers can be, for example, woven in three dimensions (3D), using a Jacquard-type loom, for example, and comprise layers of warp yarns Fc and weft yarns FT, as illustrated, for example, in [Fig. 2A]. The fibers form a fibrous preform that is inserted into the mold cavity between the two half-shells before the resin is injected.

[0013] Fig. 1E illustrates the direction Dc of the warp yarns (circumferential direction) and the direction DT of the weft yarns (axial direction) on the casing 202 of a manufactured housing.

[0014] In the example illustrated in [Fig.2A], the layer or ply C; (i=l, 4) corresponds to a layer of woven tape forming the preform. The latter comprises eight layers of fibrous texture.

[0015] The casing 202 of the housing 200 may include a multi-turn winding of the preform. In the example of [Fig. 2A], the casing 202 includes a four-turn winding of layers or plies C, 4 of woven strip forming the preform. Each ply C, 4 represents one turn.

[0016] The use of the RTM manufacturing process is particularly advantageous because it makes it possible to produce parts with a lower overall mass than the same parts when made of metallic material, while exhibiting at least equivalent, if not superior, mechanical resistance.

[0017] The retention capacity of the composite casing is ensured by the quantity of fibers, the weave pattern, and the quality of the weave. It may therefore be desirable to improve this retention capacity of turbomachine casings to guarantee blade retention in the event of blade breakage or debris entering the fan.

[0018] When a blade breaks, it fragments upon contact with the housing 200 and, in particular, with the casing 202, as illustrated in [Fig. 2B], at points CH1 and CH2. The casing 202 can then be subjected to three types of stress: - the penetrating impact, very localized, generally at the axial CHi position of the blade. It causes a perforation on the inner face 300i and high local deformations on the outer face 3002; - The non-penetrating impact, relatively localized, can occur downstream CH2 (and / or upstream) of the blade's axial position. It generates high local deformations on the inner and outer faces; and - the extended displacement / deformation wave, which begins at the main CHi, CH2 impacts, then travels from one point to another in the crankcase.

[0019] To resist penetrating impact, a solution is a localized thickening in the impact zone. As for non-penetrating impact, a solution is improved elongation at break in the impact zone.

[0020] When the housing is subjected to a deformation wave Vgb Vg2, which originates at the impact points, for example CH2, and propagates upstream Vgi and downstream Vg2 of the housing, as illustrated in [Fig. 2C]. This wave can create cracks at various locations (for example at the flanges) and place significant stress on the adjacent parts held to the flanges and the equipment attached to the housing.

[0021] It may therefore be desirable to provide a casing that allows one to avoid at least some of the aforementioned problems and constraints. Summary of the invention

[0022] A fairing housing for a fan blade for an aircraft turbomachine is therefore proposed, this housing having an annular shape around a longitudinal axis and having annular fixing flanges at its axial ends, respectively upstream and downstream, the housing comprising an intermediate section located at a distance from the flanges and configured to extend around a fan blade, the housing being made of composite material and comprising a preform made by weaving, preferably three-dimensional, warp and weft yarns and a polymer matrix in which this preform is embedded, the warp and weft yarns located in said section being made from fibers in the same material, characterized in that, between the section and at least one of the flanges, the housing comprises another section of which at least a part of the warp yarns are made from fibers in a first material of a first stiffness,and the remaining warp threads are made from fibers in a second material with a higher stiffness than the first material.

[0023] By stiffness of a fiber, we mean the capacity to resist elastic deformation, the stiffness of the fiber being characterized or defined by a modulus of elasticity or Young's modulus. Yarns made from fibers with greater stiffness therefore have increased stiffness.

[0024] The insertion of warp yarns with increased stiffness into the preform, from which the housing casing is manufactured, makes it possible to introduce a discontinuity in stiffness within the casing, particularly in the vicinity of the upstream and / or downstream flanges. Since the deformation wave does not propagate in the same way from one material to another, it is then possible to reduce or control the effects of this deformation wave depending on the stiffness of the fibers from which the warp yarns are made.

[0025] Thus, thanks to the invention it is possible to stop / slow down the wave of deformation or to reduce its effects and preserve the integrity of the housing and the adjacent parts connected to the flanges of the housing.

[0026] The invention also allows for a reduction in mass and a reduction in the environmental footprint related to the manufacture of crankcases. Indeed, by stopping or reducing the wave of deformation, the insertion of warp threads with greater stiffness (compared to the other warp threads in the preform) prevents degradation of the crankcase. In other words, the threads with increased stiffness allow for better mechanical strength of the crankcase. This improved strength makes it possible to reduce the thickness of the crankcase or to eliminate elements such as stiffeners, and therefore to obtain a gain in mass. Furthermore, a better casing design reduces the number of maintenance interventions and the need to manufacture new replacement parts.

[0027] The invention may further include one or more of the following optional features, in any technically feasible combination: - the stiffness of a fiber is defined by its modulus of elasticity or Young's modulus; - the fibers of the second material of second stiffness are intertwined fibers; - said or each other section has an axial length or dimension which represents between 2% and 20% of an internal diameter of the casing; - the warp yarns made in the second material of second stiffness are parallel to the warp yarns of the first material of first stiffness and oriented along an axis which is substantially tangent to a circumference centered on said longitudinal axis (A) of the casing (200), the weft yarns (FT) being oriented in a direction parallel to the longitudinal axis; - the warp wires (Fc) made in the second material of second stiffness represent between 50% and 100% of the total quantity of warp wires of the preform, said total quantity being defined as the sum of the warp wires (Fc) made in the first material of first stiffness and the warp wires (Fc) made in the second material of second stiffness; - the casing includes at least a first transition zone attached to an upstream axial end of said other section and a second transition zone attached to the downstream axial end of said other section opposite the upstream end, the first and second zones comprising a quantity of warp threads made of the second material of second stiffness lower than that of said other section; - the second stiffness material is Tl 100 or UMS 45 type carbon fiber and the first stiffness material is IM7 type carbon fiber.

[0028] The invention also relates to an aircraft turbomachine, comprising at least one casing as described above. Brief description of the figures

[0029] The invention will be better understood with the aid of the following description, given solely by way of example and made with reference to the accompanying drawings in which: - [Fig. 1A] is a schematic representation of a simplified view of a turbomachine according to the prior art, - Figure [1B] is a schematic representation of a partial axial cross-sectional view of a fan of an aircraft turbomachine, according to the prior art, - [Fig.lC] is a schematic representation of a perspective view of a blower housing, according to the prior art; - [Fig.1D] is a schematic representation of a partial axial cross-sectional view of a blower housing, according to the prior art; - [Fig.1E] is a schematic representation of a partial axial cross-sectional view of the casing of a crankcase, according to the prior art; - [Fig.2A] is a schematic representation of a partial axial cross-sectional view of the casing of a housing comprising a four-turn winding of a preform, according to the prior art; - [Fig.2B] is a schematic representation of a partial axial cross-sectional view of the casing of a crankcase subjected to impacts; - [Fig.2C] is a schematic representation of a partial axial cross-sectional view of the casing of a housing subjected to waves of deformation; - [Fig.3] is a schematic representation of a partial axial cross-sectional view of the casing of a housing, according to the invention; - [Fig.4] is a schematic representation of a partial axial cross-sectional view of the casing of a housing comprising a four-turn winding of a preform in which chain wires with increased stiffness are inserted on all turns, according to the invention; - [Fig.5] is a schematic representation of a partial axial cross-sectional view of the casing of a housing showing the axial extent of insertion of wires with increased stiffness, according to the invention; - [Fig.6] is a schematic representation of a partial axial cross-sectional view of the casing of a housing comprising areas having different concentrations of wires with increased stiffness, according to one embodiment of the invention; and - [Fig.7] is a schematic representation of a partial axial cross-sectional view of the casing of a housing with substitution of a stiffener by a section comprising wires with increased stiffness, according to another embodiment. Detailed description of the invention

[0030] By convention, in the description, the term "axial" refers to the orientation of structural elements extending along the direction of an axis. This axis corresponds substantially to an axis of rotation or revolution. The term "radial" refers to an orientation of structural elements extending in a direction perpendicular to the axis of rotation or revolution. The terms "internal" and "external" are used with reference to positioning relative to the axis of rotation or revolution. Thus, a structural element extending along the axis of rotation or revolution has an internal face facing the longitudinal axis and an external surface opposite its internal surface.

[0031] In the following description, the invention is applied to a housing 200 for a fan blade or a fan blade, for example, a fan 110, for an aircraft turbomachine 100. However, the invention is not limited to this type of housing 200 and can be applied to other housings of a turbomachine 100.

[0032] The housing 200 according to the invention has a general annular shape around an axis A.

[0033] Structural elements analogous to those of the prior art according to figures 1A-2C they carry the same numerical references.

[0034] The [Fig.3] illustrates a portion of the housing 200, according to the invention.

[0035] The housing 200 includes an annular shell 202 having at its axial ends annular flanges for upstream fixing 204i and downstream fixing 2042. The annular shell 202 of the housing 200 includes an intermediate section 202a located away from the flanges and configured to extend around a blower blade or a blade.

[0036] Preferably, the housing 200 is made of composite material (organic matrix composite or OMC) and includes a preform made by weaving, preferably three-dimensional (3D), warp and weft yarns and a polymeric matrix (polymer resin) in which this preform is embedded.

[0037] The housing can be made or manufactured by winding around said axis A over several superimposed turns a layer of woven strip forming the preform as shown in [Fig.2A].

[0038] The warp and weft yarns located in said section being made from fibers of the same material. For example, and without limitation, IM7 type carbon fibers.

[0039] The housing 200 may further include at least one stiffened element 302ac fixed or integrated into the casing 202 and projecting on the external surface of the casing 202 of the housing 200.

[0040] The casing 200 further comprises, between the section 202a and at least one of the flanges 204i, 2042, the casing 200 comprises another section 202b of which at least a part of the warp threads are made from fibers in a first material of a first stiffness, and the remainder of the warp threads Fc are made from fibers in a second material of a second stiffness greater than that of the first material.

[0041] The warp yarns Fc made of the second material of second stiffness are parallel to the warp yarns Fc of the first material of first stiffness and oriented along an axis that is substantially tangent to a circumference (direction Dc on [Fig. 1E]) centered on the longitudinal axis of the casing 200. The weft yarns FT are oriented in a direction parallel to the longitudinal axis A (direction DT on [Fig. 1E]).

[0042] One advantage of the structure of the 3D woven composite forming the preform is that it allows the weaving of fibers with different characteristics within the part in order to to improve the physical characteristics (elongation at break, linear mass, etc.) of the preform. For example, and without limitation, a Tl 100 type carbon fiber has a higher stiffness than an IM7 type carbon fiber. However, the characteristics of the Tl 100 fiber are not necessarily all superior (elongation at break, linear mass, etc.). It is therefore not always advisable to use a Tl 100 type carbon fiber for the entire housing.

[0043] Thus, in the present invention, the preform is made with materials of different physical characteristics. The warp threads of the intermediate section 202a are made with fibers in a first material and the warp threads of the other section 202b comprise at least some threads made with fibers in a second material in order to improve the physical characteristics (resistance to deformation, elongation at break, ...) of the housing 200.

[0044] Since the deformation wave does not propagate in the same way from one material to another, this difference in stiffness between the wires of the first material and that of the wires of the second material will have the effect of slowing down or stopping the deformation wave.

[0045] The fibers of the first material, which have low stiffness compared to that of the second material, are for example IM7 type carbon fibers.

[0046] The fibers of the second material, which are stiffer than those of the first material, are intertwined fibers (or stiff strands). These fibers are, for example, but not limited to, carbon fibers of type Tl 100 or UMS 45, preferably of type Tl 100.

[0047] The IM7 type fiber (first material) has a stiffness characterized by a Young's modulus of approximately 250 GPa. As for the Tl 100 type carbon fiber (second material), its stiffness is characterized by a Young's modulus of approximately 300 GPa, and that of the UMS45 type carbon fiber (second material) by a Young's modulus of approximately 430 GPa.

[0048] Figure 4 illustrates an axial cross-section of the casing 202 of the housing 200 obtained by winding a preform. An external diameter Dext and an internal diameter Dint of the casing define the width of the casing 202.

[0049] A 3D woven material housing can be made up of a winding of several C14 plies (as also illustrated in [Fig.2A]), each ply corresponding to a turn of the preform around the axis A.

[0050] Since the preform includes warp yarns made using fibers with increased stiffness, that is to say made from the second material with a second stiffness greater than the first stiffness of the first material, the casing 200 of the housing 200 therefore includes warp yarns with increased stiffness on all the turns (for example on four turns in the case of a preform wound on four turns).

[0051] Preferably, the warp threads Fc made of the second material of the second The stiffness represents between 50% and 100% of the total quantity of warp yarns in the preform. The total quantity of warp yarns in the preform is defined as the sum of the warp yarns Fc produced in the first material of first stiffness and the warp yarns Fc produced in the second material of second stiffness.

[0052] With reference to [Fig. 5], the warp threads made of the second material with second stiffness are arranged in a section 202b having an axial length or dimension La that represents between 2% and 20% of an internal diameter of the casing. Preferably, the axial length La is about 10% of the internal diameter. For example, and without limitation, the internal diameter can be the diameter of a fan blade at the axial position of the leading edge of the blade or the diameter of the aerodynamic duct.

[0053] In another variant shown in [Fig.6], the casing 202 further comprises at least a first transition zone 202ci attached axially to the upstream end of the section 202b comprising wires made of the second material of second stiffness, and a second transition zone 202c2 attached axially to the downstream end of the section comprising wires made of the second material of second stiffness.

[0054] In this variant, the first and second zones 202ci, 202c2 comprise a quantity of warp yarns made of the second material of second stiffness lower than that of the section 202b.

[0055] In this configuration, the casing 202 of the housing 200 includes several stiffness discontinuities that can improve the ability of the housing to resist deformation waves.

[0056] In another variant, illustrated in [Fig.7] ((1) and (2)), the presence of a section comprising chain wires with increased stiffness makes it possible to replace a stiffener present to enhance the natural modes of the housing.

[0057] In the example of [Fig.7], it is the stiffener 302c (see the first envelope illustrated in (1)) which is replaced by a section 202b (figure see the second envelope illustrated in (2)) comprising wires made of the second material of second stiffness, i.e., wires with increased stiffness.

[0058] In this configuration, the presence of the section 202b comprising wires with increased stiffness (made in the second material of second stiffness) further improves the ability of the housing to resist the vibration problems to which the housing 200 may be subjected.

[0059] Thus, advantageously, a person skilled in the art will understand that creating a discontinuity in stiffness makes it possible to stop or slow down the wave of deformation. This has the effect of reducing, for example, and without limitation, the displacements / deformations at the flanges and transmitted to adjacent parts, and therefore of avoiding a degradation of the structure of the casing and the turbomachine. The mechanical strength of the casing is therefore improved or reinforced.

[0060] The invention also allows for weight reduction and a reduction in the environmental footprint related to manufacturing. Indeed, by stopping or reducing the deformation wave, the insertion of fibers with increased stiffness into the preform prevents degradation of the housing. In other words, the fibers with increased stiffness allow for better mechanical strength of the housing. This improved strength makes it possible to reduce the thickness of the housing or to eliminate elements such as stiffeners, and therefore to achieve a weight reduction.

[0061] Better casing support also reduces the number of maintenance interventions and the manufacture of new replacement parts.

Claims

Demands

1. A housing (200) for a fan blade fairing for an aircraft turbomachine, said housing having an annular shape about a longitudinal axis (A) and comprising at its axial ends annular mounting flanges (204b, 2042), respectively upstream (204i) and downstream (2042), the housing (200) comprising an intermediate section (202a) located at a distance from the flanges and configured to extend around a fan blade, the housing (200) being made of a composite material and comprising a preform made by weaving warp (Fc) and weft (FT) yarns, and a polymer matrix in which this preform is embedded, the warp (Fc) and weft (FT) yarns located in said section (202a) being made from fibers of the same material, characterized in that, between the section (202a) and at least one of the flanges (204b 2042),The casing (200) includes another section (202b) in which at least a portion of the warp threads (Fc) are made from fibers in a first material of a first stiffness, and the remainder of the warp threads (Fc) are made from fibers in a second material of a second stiffness greater than that of the first material.

2. Carter according to claim 1, wherein the stiffness of a fiber (Fc, FT ) is defined by its modulus of elasticity or Young's modulus.

3. Housing according to claim 1 or 2, wherein the fibers (Fc) of the second material of second stiffness are interlaced fibers.

4. Housing (200) according to any one of claims 1 to 3, wherein said or each other section (202b) has an axial length or dimension (La) which represents between 2% and 20% of an internal diameter of the housing (200).

5. Casing (200) according to any one of claims 1 to 4, wherein the warp yarns (Fc) made in the second material of second stiffness are parallel to the warp yarns (Fc) of the first material of first stiffness and oriented along an axis which is substantially tangent to a circumference centered on said longitudinal axis (A) of the casing (200), the weft yarns (FT) being oriented in a direction parallel to the longitudinal axis (A).

6. A housing according to any one of claims 1 to 5, wherein the warp threads (Fc) made in the second material of second stiffness represent between 50% and 100% of the total quantity of warp threads in the preform, said total quantity being defined as the sum of the warp threads (Fc) c) made in the first material of first stiffness made and warp wires (Fc) made in the second material of second stiffness.

7. Carter (200) according to the preceding claim, wherein it comprises at least a first transition zone (202ci) attached to an upstream axial end of said other section (202b) and a second transition zone (202c2) attached to the downstream axial end of said other section (202b) opposite the upstream end, the first and second zones (202cb 202c2) comprising a quantity of warp yarns made of the second material of lower stiffness than that of said other section (202b).

8. Carter (200) according to any one of claims 1 to 7, wherein the second second stiffness material is Tl 100 type carbon fiber or UMS 45 and the first first stiffness material is IM7 type carbon fiber.

9. Carter (200) according to any one of claims 1 to 8, wherein said other section (202b) comprises, preferably, warp yarns (Fc) made from the fibers of the second second stiffness material.

10. Aircraft turbomachine (100), comprising at least one casing (200) according to any one of the preceding claims.

Images