Fixed blade assembly for a turbine engine with blades featuring adjustable blade angle

Description

TECHNICAL FIELD

[0001] This application relates to the field of turbomachinery, in particular a fixed blade of a turbomachine, for example a fixed blade comprising stator blades with variable pitch, each fixed to a pivot. The invention is particularly applicable to the unshrouded or shrouded stator of a turbomachine. STATE OF THE ART

[0002] Turbomachinery comprising at least one unducted propeller is known as an "open rotor" or "unducted fan." Such turbomachinery may comprise two unducted, counter-rotating propellers (known as CROR for "Contra-Rotating Open Rotor") or a single unducted propeller and a stator with multiple stator blades (known as USF for "Unducted Single Fan"). The propellers may be positioned at the rear of the gas generator (or engine) to be of the pusher type or at the front of the gas generator to be of the tractor type. These turbomachinery are turboprops, distinguished from turbojets by the use of an external (unducted) propeller instead of an internal fan. This allows the dilution rate to be increased very significantly without being penalized by the mass of the housings or nacelles intended to surround the propeller or fan blades.

[0003] The stator blades of the rectifier are generally mounted on a hub that carries the primary and secondary flow separation nozzle, which separates the primary flow and the flow around the inlet casing, respectively. Unlike the upstream propeller of a USF-type turbomachine, the stator blades of the rectifier are fixed in rotation relative to the axis of rotation of the upstream propeller and therefore do not experience centrifugal force.

[0004] The stator blades extend from the inlet housing and are advantageously variable-pitch. To this end, each stator blade root is pivotally mounted around a pitch axis and connected to a pitch-changing system mounted in the turbomachine. The integration area for the stator blade root and pivot is highly constrained by the presence of numerous surrounding components.

[0005] Furthermore, in such turbomachines where weight reduction is desired, stator blades are preferably made of composite material comprising a fibrous reinforcement embedded in an organic matrix.

[0006] French document FR 3 113 647 A1 describes, in particular, an unfaired variable-pitch propeller. US document 11,073,030 B1 describes, in particular, a blade attachment for a gas turbine. French document DE 10 2019 001 830 A1 describes, in particular, a composite blade.

[0007] Current propeller mounting technologies, however, do not meet the requirements for securing stator blades in a USF-type turbomachine because they are designed to clamp the blade root in a honeycomb-shaped housing using centrifugal forces generated by the blade's rotation. In a static blade, the absence of rotation, and therefore of centrifugal force, precludes the use of this simple and well-known mounting method. The blades of static blades are thus generally bolted to a metal bracket. These brackets, however, are bulky radially or tangentially, which poses integration challenges within the turbomachine. EXPOSED

[0008] One aim of this application is to remedy the aforementioned disadvantages by proposing a variable pitch blade fixing system for a static blade of a turbomachine, which reduces the radial and tangential dimensions while ensuring adequate support for the blades of the static blade.

[0009] For this purpose, a static turbine blade of a turbomachine is proposed, according to a first aspect, comprising: a blade foot comprising a fibrous reinforcement embedded in a matrix, the fibrous reinforcement comprising a first skin and a second skin separated by a cavity open on an underside face of the blade foot; a fastener configured to receive the blade foot and fix it to a hub of the blade, the fastener comprising a platform and a rib projecting from the platform, the rib being configured to penetrate the cavity so as to extend between internal faces of the first skin and the second skin; and a fastening system configured to mechanically fix the first skin and the second skin to the rib of the fastener, the fastening system passing through the first skin, the rib and the second skin.

[0010] Some preferred but not exhaustive characteristics of dawn according to the first aspect are the following, taken individually or in combination: The rib comprises two flanks connected to the platform and a crest joining the two flanks, the thickness of the rib decreasing from the platform towards the crest, and the inner faces of the skins may be more flared than the flanks of the rib; alternatively, the rib comprises two flanks connected to the platform and a crest joining the two flanks, the thickness of the rib being substantially constant from the platform towards the crest; according to yet another variant, the rib comprises two concave curved flanks such that the thickness of the rib decreases from the platform towards the crest; the first and second skins are further abutted against the platform; the fastening system comprises at least one of the following: a bolt; a plate shaped to come into contact with an outer face of the skins; the fastening system comprises a bolt passing through the first skin, the rib, and the second skin;The blade further comprises a shaping piece housed in the cavity at a distance from a rib crest; the shaping piece comprises an additional composite material including an additional fibrous reinforcement embedded in an additional matrix, the additional fibrous reinforcement comprising fibers having a Young's modulus of at least 5 GPa, for example, carbon, aramid, glass, or basalt fibers; the blade further comprises a filler piece housed in the cavity between a blade crest and the shaping piece, the filler piece possibly comprising a material having a density lower than the density of the composite material; the fibrous reinforcement has an upstream edge and a downstream edge, the cavity further being open on at least one of the upstream and downstream edges; and / or the attachment is a pivot.

[0011] According to a second unclaimed aspect, a static blade of a turbomachine is proposed comprising at least one blade conforming to the first aspect and a hub, the attachment of the blade being pivotally mounted on the hub around a shim.

[0012] According to a third unclaimed aspect, a turbomachine is proposed comprising a static blade conforming to the second aspect, further comprising a shrouded fan or an unshrouded propeller, a compression section and a turbine section, the static blade being at least one of the following blades: a shrouded fan stator, an unshrouded propeller stator, a stator of the compression section, a distributor of the turbine section.

[0013] According to a fourth unclaimed aspect, an aircraft is proposed comprising at least one turbomachine conforming to the third aspect, which can be fixed to the aircraft by means of a pylon.

[0014] According to a fifth, unclaimed aspect, a method for manufacturing a blade conforming to the first aspect is proposed, comprising the following steps: construct a blade foot comprising a fibrous reinforcement embedded in a matrix, the fibrous reinforcement comprising a first skin and a second skin separated by a cavity open on an underside of the fibrous reinforcement; insert a rib of a fastener into the cavity of the blade foot so that the rib extends between internal faces of the first skin and the second skin and a platform extends outside the cavity; mechanically fix the first skin and the second skin to the rib of the fastener.

[0015] Optionally, the blade foot fabrication step includes the following sub-steps, prior to the rib insertion step: insert successively at least one filler piece and at least one shaping piece into the cavity; place the assembly formed by the fibrous reinforcement, at least one filler piece and at least one shaping piece in a mold; and inject the matrix. DESCRIPTION OF THE FIGURES

[0016] Other features, purposes and advantages of the invention will become apparent from the following description, which is purely illustrative and not limiting, and which should be read in conjunction with the accompanying drawings on which: There figure 1 is a schematic cross-sectional view of an example of a blade conforming to a first embodiment of the invention; The figure 2 is a perspective and schematic view of an example of a fibrous reinforcement that can be used to manufacture a blade according to an embodiment of the invention; The figure 3a schematic cross-sectional view of an example of a blade conforming to a second embodiment of the invention; The figure 4 is a schematic, axial, and partial cross-sectional view of an example of a USF-type turbomachine comprising a single unshod propeller and an unshod stator to which the invention applies; and The figure 5 is a schematic view of an example aircraft that may include at least one turbomachine conforming to an embodiment of the invention.

[0017] Across all figures, similar elements bear identical references. DETAILED DESCRIPTION OF THE INVENTION

[0018] A turbomachine 1, in particular of aircraft 100, conventionally comprises at least one fan or at least one propeller 26, a compression section 27, a combustion chamber 28, a turbine section 29 downstream of the combustion chamber 28, and an exhaust casing.

[0019] The invention applies to any static blade 2 (i.e., non-rotating) of a turbomachine 1, whether it is a straightening blade 2 of a fan or propeller 26, a straightening blade 2 of the compression section 27, or a distributor blade 2 of the turbine section 29. By way of example, the turbomachine 1 may, in particular, be a USF-type turboprop comprising an unshod propeller 26, in which case the static blade 2 is unshod and extends downstream of the propeller 26 (see figure 4 ). In another example, the turbomachine 1 may be a turbojet comprising a shrouded fan, in which case the static blade 2 may correspond to the shrouded straightener extending downstream of the fan which is known by the English designation of "outer guide vane".

[0020] In this application, upstream and downstream are defined with respect to the direction of gas flow through the static blade 2. The axis of rotation of the propeller rotor 26 (or, respectively, the fan) is called the X-axis. The axial direction corresponds to the direction of the X-axis, and a radial direction is a direction perpendicular to and passing through this X-axis. Furthermore, the circumferential (or tangential) direction corresponds to a direction perpendicular to and not passing through the X-axis. Unless otherwise specified, internal and external are used with reference to a radial direction, such that the internal part or face of an element is closer to the X-axis than the external part or face of the same element.

[0021] The blade 3 will thus be defined in relation to the X axis of the rotor associated with the static blade 2 (whether it is the axis of rotation of the blower or the propeller 26 for a blower straightener, the axis of rotation of the compressor rotor for a compression section straightener 27 or the axis of rotation of the turbine rotor for a turbine section distributor 29 on which it is intended to be mounted.

[0022] In what follows, the invention will be described in the case of variable pitch blades 3, i.e. blades 3 mounted to pivot about a pitch axis Y on the hub 4 of the blade 2. This is not limiting however, the blades 3 can be fixed relative to the hub 4 when the blower is shrouded, the hub 4 then corresponding to the ferrule of the intermediate casing (which is located between the casing of the low pressure compressor and the casing of the high pressure compressor).

[0023] The static blade 2 comprises a hub 4 mounted fixed relative to a housing 30 of the turbomachine 1. It is therefore non-rotating. The blades 3 of the blade 2 extend substantially radially with respect to the X-axis.

[0024] The blades 3 here have variable pitch. The blade 2 includes an actuation mechanism 5 that allows the pitch angle of the blades 3 of the blade 2 to be modified in order to adapt the performance of the turbomachine 1 to the different phases of flight. In addition, each blade 3 includes a bracket 6 (or pivot) located at the blade root 8. The bracket 6 is rotatably mounted relative to the hub 4 around the pitch axis Y. More precisely, the bracket 6 is rotatably mounted inside a housing formed in the hub 4, by means of balls or other rolling elements.

[0025] In a manner known per se, the fastener 6 comprises a wall having an outer surface of revolution. The outer surface may, for example, have circular grooves suitable for forming raceways 6a for balls or other rolling elements.

[0026] The blade 3 includes a blade 7 with an aerodynamic profile designed to be placed in an airflow when the turbomachine 1 is in operation in order to generate lift, and a blade foot 8 configured to be attached to the hub 4 of the blade 2 via the attachment 6.

[0027] The airfoil blade 7 is shaped to define an intrados (lower surface), an extrados (upper surface), a leading edge 9, and a trailing edge 10. As is known, the leading edge 9 is configured to extend in relation to the flow of gases entering the turbomachine 1. It corresponds to the forward part of the airfoil that faces the airflow and divides the airflow into an intrados (lower surface) flow and an extrados (upper surface) flow. The trailing edge 10, for its part, corresponds to the rear part of the airfoil, where the intrados and extrados flows meet.

[0028] The blade 3 comprises two skins 12, which are joined to each other and extend generally opposite one another. In particular, the skins 12 are joined at the blade tip along the entire chord of the blade 3, at the leading edge and at the trailing edge. The skins 12 are made of a composite material comprising a fibrous reinforcement 13 densified by a matrix. They can be monolithic and made in one piece from a fibrous preform with varying thickness. Alternatively, the fibrous reinforcement 13 can comprise a first skin 12 for the lower surface and a second skin 12 for the upper surface, which are joined, for example, near the tip of the blade 3.

[0029] The fibrous reinforcement 13 may comprise three-dimensional woven or knitted fiber arrangements. It is further constructed such that it includes warp yarns that extend continuously both within the airfoil portion 7 of the blade and within the blade root portion 8. Alternatively, the fibrous reinforcement 13 may comprise two-dimensional layered fiber arrangements. The fibers of the fibrous reinforcement 13 comprise at least one of the following materials: carbon (typically silicon carbide), glass, aramid, polypropylene, and / or ceramic (typically an oxide ceramic). The matrix typically comprises an organic matrix (thermoset, thermoplastic, or elastomer) or a carbon matrix. For example, the matrix comprises a plastic material, typically a polymer, such as epoxy, bismaleimide, or polyimide.

[0030] The skins 12 of the fibrous reinforcement 13 are separated by a cavity 14 which is open on an underside 15 of the blade foot 8, thus further reducing the mass of the blade 3 compared to conventional blades 3. It should be noted that the underside 15 of the blade foot 8 corresponds to the face of the blade foot 8 that is opposite the platform 16 (shown later and visible on the Figures 1 And 3 ) of the attachment 6 when the blade foot 8 is assembled with the attachment 6. The cavity 14 is not open at the blade head.

[0031] In the case where the skins 12 are obtained by three-dimensional weaving and are monolithic, the cavity 14 is obtained by creating a debonding in the fibrous blank between two successive layers of warp, from a so-called unbound zone (including here the blade head 3) to the internal radial end of the skins 12, where the cavity 14 opens. For this, at the debonding point, the warp strands of two successive layers of the fibrous blank are not connected by weft strands, which forms the cavity 14. Preferably, the debonding extends within the aerodynamically profiled blade 7 and extends to the lower face 15 of the blade foot 8 (in order to allow the insertion of the rib 17 of the attachment 6). In the part of the blank intended to extend in the airflow (i.e. the aerodynamically profiled blade 7), the cavity 14 is not open on the leading edge 9 nor the trailing edge 10.The fibrous portions of the blank forming the leading edge 9 and the trailing edge 10 are therefore not debonded. However, in the portion of the blank forming the blade root 8 (i.e., the area intended to be attached to the fastener 6), the cavity 14 can also be opened at the upstream edges 19 and downstream edges 20 of the blade root 8 (which extend in line with the leading edge 9 and the trailing edge 10 of the blade 7), respectively. The fibrous portions of the blank forming the upstream edge 19 and the downstream edge 20 of the blade root 8 can therefore be debonded.

[0032] For example, reference can be made to document EP2588758 on behalf of the Applicant for more details on the implementation of disconnections.

[0033] The blade 3 may further include one or more filler pieces 25, typically pieces of foam or any other suitable material having a lower density than the composite material of the skins 12, placed in the portion of the cavity 14 extending within the aerodynamically profiled blade 7 in order to stiffen the skins 12 and / or give the skins 12 the final shape of the blade 7. The filler pieces 25 have, for example, a density on the order of one hundred kg / m³ and a stiffness on the order of one hundred MPa. They may, in particular, include a foam, such as an organic foam (polyethacrylimide, polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyetherimide (PEI), polyvinyl, carbon, polyisocyanurate, polyurethane, etc.).) or metallic (especially aluminum alloy), or a honeycomb of the Nomex ® type (comprising aramid fibers calendered into sheets and coated with phenolic resin), in Kevlar, in glass fibers or in aluminum.

[0034] The attachment 6 is configured to receive the blade foot 8 and fix it to the hub 4 of the static blade 2. For this purpose, the attachment 6 further comprises a platform 16 and a rib 17 projecting from the platform 16. The rib 17 is configured to penetrate the cavity 14 so as to extend between the inner faces 12a of the first skin 12 and the second skin 12. The first and second skins 12 are also mechanically fixed to the rib 17 by a fastening system 18. This configuration makes it possible to reliably fix the blade 3 to the hub 4, within a reduced radial and transverse footprint, by utilizing the internal cavity 14 of the blade 7 (located between the two skins 12) to transmit the forces from the blade 2 to the attachment 6. More specifically, the fastening system 18 passes through the first skin 12, the rib 17 and the second skin 12.The part of the attachment 6 which bears against the blade foot 8 is therefore housed inside the blade foot 8, so that it does not impact the radial or transverse dimensions of the blade 2 - unlike conventional attachments, which are placed outside the blade foot 8 and therefore necessarily encroach on the available space in the blade 2. It thus makes it possible to reduce the inter-part space and / or to use the volume gained for other functions for the motor (passage of pipe or wiring, addition of function on the surrounding parts, etc.).

[0035] Since rib 17 is housed in cavity 14 of blade root 8, its height (i.e., its dimension along the Y-axis) can be greater than the height of conventional attachments, thus improving the resistance to moments generated by aerodynamic forces. Because rib 17 can have a significant height, it presents larger bearing surfaces, thereby reducing out-of-plane stresses.

[0036] The rib 17 extends along the blade chord 3, between the upstream edge 19 and the downstream edge 20 of the blade root 8, which extend in line with the leading edge 9 and the trailing edge 10 of the blade 7, respectively. Its shape substantially follows the shape of the blade root 8. For example, the blade root 8 and the rib 17 may be substantially straight. In one embodiment, and as indicated above, the cavity 14 may also be open at the upstream edge 19 and the downstream edge 20 of the blade root 8. The rib 17 then extends along the entire cavity 14, from the upstream edge 19 to the downstream edge 20 of the blade root 8, and the skins 12 are fixed to the rib 17 over their entire width (along the axial direction, as illustrated in the figures). Figures 1 And 2 ).

[0037] The rib 17 comprises two flanks 21 and a vertex 22. The flanks 21 are connected to the platform 16 at a lower edge, the radius of which is sufficiently large to limit stress concentrations. In one embodiment illustrated in the figure 1 The flanks 21 are inclined and converge towards the apex 22, so that the thickness of the rib 17 is greater near the platform 16 than at its apex 22. This configuration of the rib 17 thus allows it to adapt to the aerodynamic profile of the blade 3 and facilitates the mounting of the blade root 8. Alternatively (see figure 3The sides 21 are substantially parallel and extend generally parallel to the Y-axis. The thickness of the rib 17 is then substantially constant from the platform towards the apex. In one embodiment, the sides 21 are flat. Alternatively, the sides 21 can be curved and symmetrical with respect to a plane passing through the Y-axis, the curvature of the sides 21 being concave such that the thickness of the rib 17 decreases towards the apex 22. The radius of curvature of the sides 21 can then be between 15 mm and 25 mm. According to yet another embodiment, the sides 21 can have a first flat section, for example parallel to the Y-axis or inclined towards the apex 22, then curve to the apex with a radius of curvature of approximately 20 mm.

[0038] To facilitate the mounting of the skins 12 onto the fastener 6 and to avoid any risk of jamming, the inner faces 12a of the skins 12 are more flared than the sides 21 of the rib 17 (see figure 1 More precisely, the inner faces 12a of the skins 12 form a first angle with a plane of symmetry of the blade foot 8 (plane normal to the figure including the alignment axis Y), and the flanks 21 form a second angle with this plane; the first angle is then larger than the second angle (see figure 1 ).

[0039] Preferably, the inner radial end of the skins 12 rests against the platform 16. In the example illustrated on the figure 1 , the inner radial end of the skins 12 corresponds to the lower face 15 of the blade foot 8. In the example illustrated on the figure 3The skins 12 are pressed onto the rib 17 so that their inner face 12a is in contact with both the sides of the rib 17 and the platform 16. The inner radial end of the skins 12 then corresponds to their inner face 12a. Regardless of the embodiment, the platform 16 and the inner radial ends (15 / 12a) of the skins 12 therefore serve as reference surfaces for the radial positioning of the blade 3 relative to the attachment 6.

[0040] The tangential positioning of the blade 3 is ensured by the contact of the inner faces 12a of the skins 12 with the rib 17, since the fixing system 18 presses the skins 12 of the blade 3 against the flanks 21 of the rib 17. The flanks 21 of the rib 17 and the inner faces 12a of the skins 12 therefore form the reference surfaces for the tangential positioning of the blade foot 8 with respect to the attachment 6.

[0041] Optionally, the reference surfaces of the blade foot 8 are produced by machining a sacrificial thickness of the composite material. The sacrificial thickness corresponds to a non-structural part of the blade 3, which can, for example, be obtained by adding plies of pre-impregnated composite material co-injected with the preform of the fiber reinforcement 13. The composite material plies may, in particular, include glass fibers embedded in a matrix, preferably a matrix compatible with the matrix of the fiber reinforcement 13 of the skins 12 (typically, the same matrix).

[0042] The fastening system 18 may include any suitable means for mechanically fixing the blade foot 8 to the attachment 6. For example, the fastening system 18 includes a bolt 31 passing through the first skin 12, the rib 17, and the second skin 12. In one embodiment, the fastening system 18 includes several bolts 31 distributed between an upstream end and a downstream end of the rib 17. The screws of the bolts 31 are then inserted into through-holes formed in the skins 12 and the rib 17. A single bolt 31 thus passes through both skins 12 and the rib 17.

[0043] When the rib 17 extends over the entire chord of the blade 3, the fastening system 18 comprises bolts 31 distributed equidistantly from the upstream edge 19 to the downstream edge 20 of the blade root 8. For example, for a stator blade 3 of a USF-type turboprop, the fastening system 18 comprises between three and six bolts 31 distributed equidistantly between the leading edge 9 and the trailing edge 10 of the blade 3. Optionally, a counterbore may be made in the outer face of the skins 12 to improve the bearing surface of the screw heads of the bolts 31.

[0044] Alternatively or in addition, the fastening system 18 may include a metal plate 23 (see figure 3) attached and bolted to each skin of the fibrous reinforcement 13. Optionally, a counterbore can be made in the plate 23 to improve the bearing surface of the screw heads of the bolts 31. The plate 23 can be substantially flat and pressed against the corresponding skin 12 by the bolts 31. In the embodiment in which the inner faces 12a of the skins 12 are also in contact with the platform 16 (see figure 3 for example), the plate 23 can be bent and include a first portion configured to press the skin 12 opposite the fibrous reinforcement 13 against the corresponding side 21 of the rib 17 and a second portion configured to press the free end of this same skin 12 against the platform 16.

[0045] Plate 23 (straight or angled) helps in particular to take over moments, especially in case of object ingestion, and to dissipate energy by plastic deformation in case of significant bending of blade 3.

[0046] In one embodiment, the blade 3 further includes a shaping piece 24, placed in the cavity 14, near the apex 22 of the rib 17, in order to reinforce the stiffness of the blade 3 at the bottom of the blade 7. The shaping piece 24 also aims to ensure a gradual stiffness transition in the radial direction, in order to avoid stress concentrations at the exit of the clamping zone.

[0047] The shaping piece 24 is positioned in the cavity 14 so as to extend close to the rib 17 while maintaining a functional clearance between the shaping piece 24 and the rib 17 in order to ensure the mounting of the blade foot 8. The clearance can be on the order of a few millimeters for example.

[0048] If necessary, the shaping piece 24 is placed between the apex 22 of the rib 17 and the filling piece(s) 25.

[0049] The conforming part 24 may, in particular, be made of a composite material comprising a fibrous reinforcement embedded in a matrix, preferably a matrix compatible with the matrix of the fibrous reinforcement 13 of the skins 12 (typically, the same matrix). The fibrous reinforcement of the conforming part 24 may, in particular, comprise fibers with a Young's modulus greater than 5 GPa, for example, carbon, aramid, glass, or basalt fibers. Manufacturing process

[0050] A blade 3 conforming to the invention can in particular be obtained in accordance with the following steps.

[0051] A fibrous rough-out of the two skins 12 is produced, for example by weaving or knitting. In one embodiment, the fibrous rough-out is woven in three dimensions with one or more unlinking to obtain the two skins 12 and the cavity 14. The two skins 12 are monolithic at the tip, the leading edge 9, and the trailing edge 10 of the blade 7. The cavity 14 is open on the inner face 15 of the blade root 8 and extends into the center of the blade 7.

[0052] Alternatively, the 12 skins can be woven separately in two or three dimensions, then joined together during cooking (co-cooking).

[0053] If necessary, cavity 14 is also open on the upstream edge 19 and the downstream edge 20 of the dawn foot 8.

[0054] At least one filling piece 25 is then placed at the bottom of the cavity 14. Then, at least one shaping piece 24 is placed in the cavity 14, for example resting against the filling piece(s) 25. The shaping piece 24 seals the cavity 14 and is positioned so as to leave a gap with the rib 17 after assembly.

[0055] Optionally, plies of pre-impregnated composite material are placed against the skin surfaces intended to form reference surfaces, namely the inner faces 12a of the skins 12, in the area intended to come into contact with the flanks 21 of the rib 17, and on the inner radial end of the skins 12.

[0056] The assembly formed by the fiber blank, the filler pieces 25 and shaping pieces 24, and, where applicable, the composite material plies, is placed in a mold having a cavity shaped like the final molded part (namely, the blade 7 and the blade root 3). Material (the "matrix" of the composite material), generally plastic, is injected into the mold so as to impregnate the fiber reinforcement 13 of the skins 12 and the shaping and filler pieces. The matrix injection can be carried out using an injection technique such as RTM or VARRTM. In the case of a plastic material, the injected matrix is, for example, a thermosetting liquid composition containing an organic precursor of the matrix material. The organic precursor is usually in the form of a polymer, such as a resin, possibly diluted in a solvent.As is well known, the plastic material is then heated to induce polymerization, for example through cross-linking. For this purpose, the mold is placed in an oven.

[0057] The resulting part is then demolded and, optionally, machined to remove excess length and obtain a part with the desired shape, despite any potential shrinkage of the fibers in the fibrous reinforcement 13 during the polymerization of the plastic. Sacrificial thicknesses are machined to obtain the reference surfaces of the blade root 8. Through-holes are also machined in the skins 12 to accommodate the fastening system 18. If necessary, counterbores are also machined around the through-holes.

[0058] The attachment 6 is then put in position on the blade foot 8 by placing the rib 17 in the cavity 14, between the inner faces 12a of the skins 12. After insertion of the attachment 6, the apex 22 of the rib 17 extends preferably a short distance from the shaping piece 24.

[0059] Preferably, through passages, intended to receive the fastening system 18 and extending opposite the through passages machined in the skins 12, are formed through the flanks 21 of the rib 17 before its insertion into the cavity 14.

[0060] Finally, the fastening system 18 is attached and fixed to the skins 12 and the fastener 6 in order to secure the blade foot 8 and the rib 17. For example, bolts 31 are inserted and fixed in the through passages of the skins 12 and the fastener 6.

[0061] The manufacturing process is therefore simpler than for blades with conventional attachments, the number of components required to manufacture blade 3 is reduced and the steps of weaving or knitting the fibrous preform are simplified.

Claims

1. A vane (3) of a static vane assembly (2) of a turbomachine (1) comprising: - a vane root (8) comprising a fiber reinforcement (13) embedded in a matrix, the fiber reinforcement (13) comprising a first skin (12) and a second skin (12) separated by a cavity (14) open onto a lower face (15) of the vane root (8); - a fastener (6) configured to receive the vane root (8) and to attach it to a hub (4) of the vane assembly (2), the fastener (6) comprising a platform (16) and a rib (17) protruding from the platform (16), the rib (17) being configured to enter into the cavity (14) so as to extend between inner faces (12a) of the first skin (12) and of the second skin (12); and - an attaching system (18) configured to mechanically attach the first skin (12) and the second skin (12) to the rib (17) of the fastener (6), the vane (3) being characterized in that the attaching system traverses the first skin (12), the rib (17) and the second skin (12).

2. The vane (3) as claimed in claim 1, wherein the rib (17) comprises two side faces (21) connected to the platform (16) and an apex (22) connecting the two side faces (21), a thickness of the rib (17) being decreasing from the platform (16) in the direction of the apex (22).

3. The vane (3) as claimed in claim 1, wherein the inner faces (12a) of the skins (12) are more flared than the side faces (21) of the rib (17).

4. The vane (3) as claimed in claim 1, wherein the rib (17) comprises two side faces (21) connected to the platform (16) and an apex (22) connecting the two side faces (21), a thickness of the rib (17) being substantially constant from the platform (16) in the direction of the apex (22).

5. The vane (3) as claimed in one of claims 1 to 4, wherein the first and the second skin (12) are moreover in abutment against the platform (16).

6. The vane (3) as claimed in one of claims 1 to 5, wherein the attaching system (18) comprises at least one of the following elements: a bolt (31); a plate (23) shaped to come into contact with an outer face of the skins (12).

7. The vane (3) as claimed in claim 6, wherein the attaching system (18) comprises a bolt (31), the bolt (31) traversing the first skin (12), the rib (17) and the second skin (12).

8. The vane (3) as claimed in one of claims 1 to 7, further comprising a shaping part (24) housed in the cavity (14) distant from an apex (22) of the rib (17).

9. The vane (3) as claimed in claim 8, wherein the shaping part (24) comprises an additional composite material comprising an additional fiber reinforcement embedded in an additional matrix, the additional fiber reinforcement (13) comprising fibers having a Young modulus at least equal to 5 GPa, for example fibers of carbon, aramid, glass or basalt.

10. The vane (3) as claimed in one of claims 8 and 9, further comprising a filling part (25) housed in the cavity (14) between an apex (22) of the vane (3) and the shaping part (24), the filling part (25) being able to comprise a material, a density of which is less than the density of the composite material.

11. The vane (3) as claimed in one of claims 1 to 10, wherein the fiber reinforcement (13) has an upstream edge (19) and a downstream edge (20), the cavity (14) being moreover open onto at least one from among the upstream edge (19) and the downstream edge (20).

12. The vane (3) as claimed in one of claims 1 to 11, wherein the fastener (6) is a pivot.