Casing for an aircraft turbine engine

Abstract

The invention relates to a casing (200) for the fairing of a fan blade for an aircraft turbine engine, this casing having an annular shape about an axis (A) and including, at its axial ends, annular attachment flanges (2041, 2042), upstream (2041) and downstream (2042), respectively, the casing comprising an intermediate segment (202a) located at a distance from the flanges and configured to extend around a fan blade, the casing being made of composite material and comprising a winding around the axis over several stacked turns of a layer of woven strip forming a preform, and a polymer matrix in which this winding is embedded, the casing further comprises an upstream annular stiffening insert (310a) integrated into the winding and axially inserted between the upstream flange and the intermediate segment, and a downstream annular stiffening insert (310b) integrated into the winding and axially inserted between the downstream flange and the intermediate segment.

Description

Description TITLE: CASING FOR AN AIRCRAFT TURBOMACHINE Technical field of the invention

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

[0002] Known from the prior art are documents US-B2-11 891 910, US-A1- 2019 / 211705 and FR-A1-3 134 137.

[0003] 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 fan 110, one or more compressors 102i, 1022, a combustion chamber 104, one or more turbines 1061, 1062 and an ejection nozzle 108 for the combustion gases leaving the turbine(s).

[0004] Figure 1B schematically and partially illustrates a fan 110 of a turbomachine. The fan 110 comprises a fan blade or a bladed wheel 112 which is surrounded by a fan or fairing casing 200, also called a retention casing due to its function of retaining the blades in the event of their rupture, or in the event of debris entering the fan.

[0005] With reference to Figure 1C, a fan casing 200, and more generally a casing 200, typically comprises an annular envelope 202, which may be, for example and in a non-limiting manner, made of metallic material or of composite material from woven fibers embedded in a polymeric resin. Preferably, the annular envelope is made of composite material.

[0006] In a context of reducing the ecological footprint of aircraft, the use of a lightweight but equally high-performance material, such as composite material, makes it possible to significantly improve the environmental performance of aircraft by reducing their mass and, at the same time, their fuel consumption.

[0007] Still with reference to Figure 1C, the annular casing 202 has an axis of revolution A and extends around the fan blades 112 of the turbomachine. The casing 200 comprises an annular fixing flange 204i, 2042 at each of the axial ends of the annular casing 202. These flanges 204i, 6042 are used to fix the casing 200 to annular walls of a nacelle which surrounds the turbomachine to form an aircraft propulsion assembly.

[0008] The casing 200 may, for example, be connected by the flanges 204i, 2042 on the one hand to an air inlet sleeve 4a located upstream of the fan casing 200, and on the other hand, to an intermediate casing shroud located downstream of the fan casing 200. The fan casing 600 also comprises upstream acoustic panels 210, as illustrated in FIG. 1 D, and downstream acoustic panels (not shown).

[0009] With reference to Figure 1D, an abradable annular cartridge may be positioned on an internal annular surface 300i (Figure 1C) of the casing 202 of the housing 200, between the upstream acoustic panels 210 and the downstream acoustic panels. This abradable cartridge may 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 intended to wear in a controlled manner during operation. As for the panel 206, it may, for example, be solid or have a honeycomb structure. The housing 200 may further comprise at least one stiffener 302 a-c fixed on the external surface 3002 of the casing 202 as illustrated, for example, in FIG. 1 E. The stiffeners contribute to reinforcing or improving the rigidity of the casing 200.

[0010] In addition to the retention function, the casing 200 is further designed to: ensure mechanical continuity (of forces and moments) between the air inlet sleeve and the intermediate casing shell; allow the fixing of the abradable annular cartridge panels, the upstream acoustic panels and the downstream acoustic panels, thus ensuring continuity of the aerodynamic vein; allow the fixing of equipment and supports known per se, in particular inside the nacelle; meet the fire and leak regulation specifications; allow continuity of the electrical current for lightning resistance, etc.

[0011] 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 bonded to the panel 206.

[0012] It has already been proposed to manufacture the fan casing from a composite material from woven fibers embedded in a polymer resin, the manufacturing process being of the "RTM" type (acronym for "Resin Transfer Molding").

[0013] In an RTM manufacturing process, a mold comprising two half-shells, placed one on top of the other, confines a molding cavity. The fibers can be, for example, woven in three dimensions (3D), via a Jacquard loom for example, and comprise layers of warp yarns Fc and weft yarns FT as illustrated for example in Figure 2A. The fibers form a fibrous preform which is inserted into the mold cavity between the two half-shells, before injection of the resin.

[0014] Figure 1 E, illustrates direction D cof the warp threads (radial or circumferential direction) and the direction DT of the weft threads (axial direction) on the casing 202 of a manufactured casing.

[0015] In the example illustrated in Figure 2A, the layer or ply Ci (i=1, 4) corresponds to a layer of woven strip forming the preform. The latter comprises eight layers of fibrous texture.

[0016] Generally, the casing 202 of the casing 200 comprises a winding over several turns of the preform. In the example of FIG. 2A, the casing 202 comprises a winding over four turns of layers or plies CM of preform. Each ply C1-4 represents one turn.

[0017] The use of the RTM manufacturing process is particularly advantageous because it allows the production of parts with a lower overall mass than the same parts when made of metallic material, while presenting at least equivalent, if not superior, mechanical resistance.

[0018] 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 ensure the retention of blades in the event of their breakage, or in the event of debris entering the fan.

[0019] When a blade breaks, it fragments upon contact with the casing 200 and in particular the envelope 202, as illustrated in FIG. 2B, at points CH1 and CH2. The envelope 202 can then be subjected to three types of stress: the perforating impact, very localized, generally at the axial position CHi of the blade. It causes a perforation on the internal face 300i and high local deformations on the external face 3002; the non-perforating impact, relatively localized, can occur downstream CH2 (and / or upstream) of the axial position of the blade. It causes high local deformations on the internal and external faces; and the displacement / deformation wave, extended, which begins at the main impacts CH1, CH2, then travels from one point to another of the casing.

[0020] To resist perforating impact, one solution is localized thickening in the impact zone. As for non-perforating impact, one solution is greater elongation at break in the impact zone.

[0021] When the casing is subjected to a deformation wave Vg-i, Vg2, the latter which initiates at the impacts, for example CH2, and propagates upstream Vgi and downstream Vg2 of the casing, as illustrated in figure 2C. This wave can create cracks at different locations (for example at the flanges) and strongly stress the adjacent parts held to the flanges and the equipment attached to the casing. The stiffeners of the previous documents, mentioned above, are however not suitable for stopping or slowing down these deformation waves Vgi, Vg2.

[0022] It may therefore be desirable to provide a casing which makes it possible to overcome at least some of the aforementioned problems and constraints. Summary of the invention

[0023] There is therefore proposed a fairing casing for a fan blade for an aircraft turbomachine, this casing having an annular shape around an axis A and comprising at its axial ends respectively upstream and downstream annular fixing flanges, the casing comprising an intermediate section located at a distance from the flanges and configured to extend around a fan blade, the casing being made of composite material and comprising a winding around said axis on several superimposed turns of a layer of woven strip forming a preform, and a polymer matrix in which this winding is embedded, the casing further comprising an upstream annular stiffening insert integrated in said winding and axially interposed between the upstream flange and said section, and a downstream annular stiffening insert integrated in said winding and axially interposed between the downstream flange and said section, characterized in that each of the upstream and downstream inserts is arranged axially between two superimposed turns of the layer of woven strip forming the preform or inside the layer of woven strip forming the preform.

[0024] The positioning of an insert in the casing shell makes it possible to introduce a discontinuity of stiffness in the casing shell, particularly in the vicinity of the upstream and 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 insert.

[0025] In addition, the integration of the insert deep into sub-layers of the preform makes it possible to improve the reduction or control of the effects of the deformation wave made possible by the introduction of the stiffness discontinuity.

[0026] Thus, thanks to the invention it is possible to stop / slow down the deformation wave or reduce its effects and preserve the integrity of the casing and adjacent parts connected to the casing flanges.

[0027] The invention also allows for weight savings and a reduction in the ecological footprint related to the manufacture of casings. Indeed, by stopping or reducing the deformation wave, the insert prevents damage to the casing. In other words, the insert allows for better mechanical strength of the casing. This better strength makes it possible to reduce the thickness of the casing or to remove elements such as stiffeners, and therefore to obtain a weight saving. Furthermore, better strength of the casing makes it possible to reduce the number of maintenance interventions and the manufacture of new replacement parts.

[0028] The invention may further comprise one or more of the following optional features, in any technically possible combination: each of the upstream and downstream inserts has an axial length or dimension that represents between 1% and 10% of an internal diameter of the casing; each of the upstream and downstream inserts is wound with the layer of woven strip forming the preform over at least one turn around the axis; each of the upstream and downstream inserts is an elongated and continuous strip; each of the upstream and downstream inserts is an elongated strip formed by a succession of independent parts; each of the upstream and downstream inserts is made of a metal alloy, for example a titanium alloy or steel; each of the upstream and downstream inserts has an elliptical or trapezoidal or circular or rectangular shape in axial section.

[0029] The invention also relates to a turbomachine comprising a casing as described above. Brief description of the figures

[0030] The invention will be better understood with the aid of the following description, given solely by way of example and with reference to the appended drawings in which: Figure 1 A is a schematic representation of a simplified view of a turbomachine according to the prior art, Figure 1 B is a schematic representation of a partial axial sectional view of a fan of an aircraft turbomachine, according to the prior art, Figure 1 C is a schematic representation of a perspective view of a fan casing, according to the prior art; Figure 1 D is a schematic representation of a partial axial sectional view of a fan casing, according to the prior art; Figure 1 E is a schematic representation of a partial axial sectional view of the casing of a casing, according to the prior art;Figure 2A is a schematic representation of a partial axial sectional view of the casing of a housing comprising a winding over four turns of a preform, according to the prior art; Figure 2B is a schematic representation of a partial axial sectional view of the casing of a housing subjected to impacts; Figure 2C is a schematic representation of a partial axial sectional view of the casing of a housing subjected to waves of deformation; Figure 3 is a schematic representation of a partial axial sectional view of the casing of a housing, according to the invention; Figure 4 is a very schematic representation of the positioning of an insert between two layers of the casing of the casing of Figure 3 according to a first variant; Figure 5A is a schematic representation of a view of the insert in the winding of the casing of the casing, according to a first variant; Figure 5B is a schematic representation of a profile view of the insert in the winding of the casing of the casing, according to a second variant; Figure 6 is a schematic representation of the positioning of an insert inside the same layer of the casing of the casing of Figure 3 according to a second variant; Figure 7 is a schematic representation of a partial axial sectional view of the casing of a casing showing the axial extent of the insert, according to the invention; and Figure 8 is a schematic representation of the positioning of the insert at a given angular position with respect to an accessory, according to one embodiment. Detailed description of the invention

[0031] By convention, in the description, the term "axial" qualifies the orientation of structural elements extending in the direction of an axis. This axis corresponds substantially to an axis of rotation or revolution. The term "radial" qualifies an orientation of structural elements extending in a direction perpendicular to the axis of rotation or revolution. The terms "internal" and "external" are used in reference to a 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.

[0032] In the following description, the invention is applied to a casing 200 for fairing a fan blade or a vane, for example a fan 110, for an aircraft turbomachine 100. The invention is however not limited to this type of casing 200 and can be applied to other casings of a turbomachine 100.

[0033] The casing 200 according to the invention has a generally annular shape around an axis HAS.

[0034] Structural elements similar to those of the prior art according to Figures 1A-2C bear the same numerical references.

[0035] Figure 3 illustrates a portion of the casing 200, according to the invention.

[0036] The casing 200 comprises an annular casing 202 having at its axial ends upstream 204i and downstream 2042 annular fixing flanges. The annular casing 202 of the casing 200 comprises an intermediate section 202 alocated away from the flanges and configured to extend around a fan blade or blading.

[0037] Preferably, the casing 200 is made of composite material and comprises a winding around said axis A on several superimposed turns of a layer of woven strip forming a preform, and a polymer matrix (polymer resin) in which this winding is embedded. The woven strip may be, for example, a three-dimensional (3D) weave of fibers.

[0038] The casing 200 may further comprise at least one stiffening element 302. a-c fixed or integrated into the casing 202 and projecting from the external surface of the casing 202 of the housing 200.

[0039] The casing 200 further comprises at least one upstream annular insert 310 a and a downstream annular stiffening insert 310b integrated into said winding.

[0040] The upstream insert 310 ais inserted axially between the upstream flange 204i and the section 202 a of the casing 202 and, the downstream insert 310b is interposed axially between the downstream flange 2042 and the section 202 a of envelope 202.

[0041] According to a first variant illustrated in figure 4, each of the upstream inserts 310 a and downstream 310b is arranged axially between two superimposed turns of the woven strip layer forming the preform.

[0042] Still according to Figure 4, illustrating a very schematic axial sectional view of the casing 202 of the housing 200, it can be observed that the casing is made up of a winding on four turns represented by four folds C1-4. The insert 310 is interposed between the second fold C2 and the third fold C3.

[0043] A 3D woven material casing consists of a winding of several C1-4 plies. It is therefore possible to place the insert between two plies at a given axial position. Thus, each of the upstream inserts 310 a and downstream 310b is wound with the woven strip layer forming the preform at least one turn around the axis.

[0044] Each of the upstream inserts 310 a and downstream 310b is an elongated strip.

[0045] In one variant, illustrated in Figure 5A, the preform is wound on a Ci turn or fold. In this example, the insert is substantially circular and continuous.

[0046] Since the casing is made up of a continuous winding over several turns of the woven strip layer forming the preform, the insert can be formed from a succession of pieces joined end to end to create a continuous assembly.

[0047] According to another variant, each of the upstream and downstream inserts is an elongated strip formed by a succession of parts 311 a -d independent as illustrated for example, and in a non-limiting manner, in figure 5B.

[0048] Generally, the insert can be inserted on 1 turn (as shown in Figures 5A and 5B) or on all turns.

[0049] With reference to Figure 6, which represents a variant of positioning or integration of the insert in the casing of the housing, the upstream and downstream inserts can be arranged axially inside the layer of woven strip forming the preform.

[0050] Indeed, due to its 3D woven material structure, the woven tape layer forming the preform includes a set of sub-layers making it possible to add the insert within the same ply. In the example of Figure 6, the composite ply C3 is untied (separated into 2 parts locally) for positioning or arranging the insert.

[0051] The insert can be positioned on all interfaces including internal or external surfaces, the insertion being carried out on an axially restricted area.

[0052] Referring to Figure 7, each of the upstream inserts 310 a and downstream 310b has an axial length or dimension L a which represents between 1% and 10% of an internal diameter of the casing. Preferably, the axial length L a is approximately 5% of the internal diameter. For example, and without limitation, the internal diameter may be the diameter of a fan blade at the axial position of the leading edge of the blade or the diameter of the aerodynamic vein.

[0053] However, the axial position of the zone may be different from one design to another of the casing 200.

[0054] The upstream insert 310 a and / or downstream 310b has an elliptical or trapezoidal or circular or rectangular shape in axial section. Inserts may also be integrated having an identical or different shape in axial section. For example, and in a non-limiting manner, the upstream insert 310 amay have a trapezoidal shape in axial section and the downstream insert 310b, an elliptical shape.

[0055] Each of the upstream and downstream inserts is made of a metal alloy. For example, and without limitation, the inserts are made of titanium alloy or steel.

[0056] Thus, the preform and the insert are made of materials with different characteristics. The metal alloy is made so as to have, for example, and in a non-limiting manner, a stiffness ranging from 110 to more than 200 GPa while the injected 3D woven composite material (organic matrix composite or OMC) has a stiffness ranging from 50 to 100 GPa.

[0057] In another embodiment, illustrated in Figure 8, the casing may comprise an insert integrated into an angular portion of the annular casing of the casing and capable of protecting at least one accessory fixed on the external surface of the casing 202 of the casing 200.

[0058] In this embodiment, the axial length of the insert may be greater than previously described in order to provide protection of the at least one accessory over a sufficient length.

[0059] Advantageously, the person skilled in the art will understand that the creation of a stiffness discontinuity makes it possible to stop or slow down the deformation wave. This has the consequence of reducing, for example, and in a non-limiting manner, the displacements / deformations at the flanges and transmitted to the adjacent parts and therefore of avoiding degradation of the structure of the casing and the turbomachine. The mechanical strength of the casing is therefore improved or reinforced.

[0060] Furthermore, the integration of the insert in depth of the sub-layers of the preform (as in the examples of figures 4 and 6), advantageously makes it possible to improve the stopping or slowing down of the deformation wave, unlike the solutions of the prior art where the inserts are integrated in the external or superficial layers of the preform. Such inserts can be effective for deformations or impacts in radial directions but are not effective, in particular, against deformation waves propagating in axial direction in deep sub-layers of the preform. Thus, due to their positioning, the prior art inserts, which are more like stiffeners projecting from an external surface of the casing, are not effective in protecting parts located at the flanges.

[0061] The invention also allows for a weight saving and a reduction in the ecological footprint related to manufacturing. Indeed, by stopping or reducing the deformation wave, the insert prevents damage to the casing. In other words, the insert allows for better mechanical strength of the casing. This improved strength makes it possible to reduce the thickness of the casing or to eliminate elements such as stiffeners, and therefore to obtain a weight saving.

[0062] Better casing performance also reduces the number of maintenance interventions and the manufacturing of new replacement parts.

Claims

Claims [1] Casing (200) for fairing a fan blade for an aircraft turbomachine, this casing (200) having an annular shape around an axis (A) and comprising at its axial ends annular flanges (204i, 2042) for fixing, respectively upstream (204i) and downstream (2042), the casing (200) comprising an intermediate section (202 a ) located at a distance from the flanges and configured to extend around a fan blade, the casing (200) being made of composite material and comprising a winding around said axis on several superimposed turns (CM) of a layer of woven strip forming a preform, and a polymer matrix in which this winding is embedded, the casing (200) further comprising an annular insert (310 a ) upstream stiffening integrated into said winding and interposed axially between the upstream flange (204i) and said section (202 a), and a downstream annular stiffening insert (310b) integrated into said winding and interposed axially between the downstream flange (2042) and said section (202 a ), characterized in that each of the upstream inserts (310 a ) and downstream (310b) is arranged axially between two superimposed turns (C2, C3) of the woven strip layer forming the preform or inside the woven strip layer. [2] The housing (200) of claim 1, wherein each of the upstream inserts (310 a ) and downstream (310b) has an axial length or dimension (L a ) which represents between 1% and 10% of an internal diameter of the casing (200). [3] Housing (200) according to one of claims 1 or 2, in which each of the upstream inserts (310 a ) and downstream (310b) is wound with the woven strip layer forming the preform over at least one turn around the axis (A). [4] Housing (200) according to one of claims 1 to 3, in which each of the upstream inserts (310 a ) and downstream (310b) is an elongated and continuous strip. [5] Housing (200) according to one of claims 1 to 3, in which each of the upstream inserts (310 a ) and downstream (310b) is an elongated strip formed by a succession of independent pieces (311 a -d). [6] Housing (200) according to one of claims 1 to 5, in which each of the upstream inserts (310 a ) and downstream (310b) is made of metal alloy, for example titanium alloy or steel. [7] Housing (200) according to one of claims 1 to 6, in which each of the upstream inserts (310 a ) and downstream (310 a ) has an elliptical or trapezoidal or circular or rectangular shape in axial section. [8] Aircraft turbomachine (100), comprising at least one casing (200) according to one of the preceding claims.

Images