Fixed vane assembly for a turbine engine comprising variable-pitch blades

Abstract

The present application relates to a blade (7) of a static vane assembly (6a) of a turbine engine (1) comprising: - a blade root (14); - a hub (8) configured to receive the blade root (14) and secure it with respect to the vane assembly (6a); - a first jaw (15a) mounted on the hub (8); and - a second jaw (15b) mounted on the hub (8), movable with respect to the first jaw (15a) between a first configuration in which the second jaw (15b) extends away from the blade root (14) and a second configuration in which the second jaw (15b) clamps the blade root (14) against the first jaw (15a).

Description

[0001] DESCRIPTION

[0002] TITLE: Fixed turbomachine vane comprising variable-pitch blades

[0003] TECHNICAL FIELD

[0004] The present application relates to the field of turbomachines, in particular a fixed blade of a turbomachine, for example a fixed blade comprising variable-pitch stator blades, each fixed to a pivot. The application applies in particular to the unducted rectifier of a turbomachine or to the ducted rectifier of a turbomachine, in particular aeronautical.

[0005] STATE OF THE ART

[0006] Turbomachines comprising at least one unducted propeller are known by the English term "open rotor" or "unducted fan". Such turbomachines can comprise two unducted and contra-rotating propellers (known by the English acronym CROR for "Contra-Rotating Open Rotor"), or a single unducted propeller and a rectifier comprising several stator blades (known by the English acronym USF for "Unducted Single Fan").

[0007] In a USF-type turbomachine, the stator vanes of the rectifier are generally fixed by their root to a hub which carries the nozzle separating the primary flow from the secondary flow, by means of a metal fastener associated with bolts. This type of fixing is however bulky, which poses difficulties in integrating the rectifier into the turbomachine.

[0008] Furthermore, the attachment is subjected to significant bending forces, and the areas of the stator blade roots of the rectifier into which the bolts are inserted form stress concentration zones which undergo an asymmetrical force due to the pressure differences experienced by the intrados and by the extrados of the blade.

[0009] GENERAL STATEMENT

[0010] One aim of the present application is to reduce the size of the system for fixing the blades of a static blade of a turbomachine while guaranteeing suitable support for these blades.

[0011] For this purpose, according to a first aspect, a blade of a static blade of a turbomachine is proposed, comprising: a blade root; a hub configured to receive the blade root and fix it relative to the blade; a first jaw mounted on the hub; and a second jaw mounted on the hub movable relative to the first jaw between a first configuration, in which the second jaw extends at a distance from the blade root, and a second configuration in which the second jaw presses the blade root against the first jaw.

[0012] Advantageously, a recess is formed in a surface of the hub, the second jaw and the blade root being at least partially inserted into the recess. Advantageously, dimensions and a shape of the recess correspond to dimensions and a shape of the portions of the blade root and the second jaw which are inserted into the recess so as to immobilize the blade root and the second jaw.

[0013] In one embodiment, the first jaw is mounted on a surface of the hub by being monolithic with the surface.

[0014] Advantageously, the hub comprises a clip mounted movably relative to the hub, the first jaw and the second jaw being mounted on a surface of the clip.

[0015] Preferably, each of the jaws comprises a bearing face configured to be in contact with the blade root, a base configured to be mounted on the hub and a rib connecting the bearing face and the base.

[0016] Preferably, the second jaw further comprises an insertion portion extending radially inward from the base and the hub further comprises a groove configured to receive the insertion portion and guide the second jaw between the first and second configuration.

[0017] In one embodiment, the insertion portion and the groove have a dovetail section.

[0018] Advantageously, all or part of the ends of the first and second jaws are chamfered or have a fillet.

[0019] Advantageously, the blade further comprises at least one first means for fixing the second jaw to the hub and at least one second means for fixing the second jaw to the first jaw, the at least one second fixing means passing through the blade root.

[0020] The invention also relates to a method for assembling a blade according to the invention, comprising the following steps: producing a blade root; producing a hub and a first jaw, the first jaw being mounted on the hub; placing the blade root in the hub against the first jaw; and attaching and fixing a second jaw to the hub so as to press the blade root against the first jaw.

[0021] DESCRIPTION OF FIGURES

[0022] Other characteristics, aims and advantages of the application will emerge from the following description, which is purely illustrative and not limiting, and which must be read in conjunction with the appended drawings in which:

[0023] Figure 1 schematically illustrates, in axial and partial section, an example of a turbomachine which may comprise a blade of a static blading in accordance with the teaching of the present application;

[0024] Figure 2 is a partial schematic sectional view of an exemplary embodiment of a blade of a static blading system in accordance with the teaching of the present application; and

[0025] Figure 3 is a flowchart of steps of a method in accordance with the teaching of the present application. Throughout the figures, similar elements bear identical references.

[0026] DETAILED DESCRIPTION

[0027] A turbomachine 1 , in particular for an aircraft, comprises, from upstream to downstream, in the direction of flow of the gases in operation, a fan section, for example comprising a propeller 2 or a fan, a compression section 3, a combustion chamber 4, a turbine section 5, and an exhaust casing. The fan section generates most of the thrust. To do this, its rotor part is driven by the rotor part of the turbine section 5 which expands air burned by the combustion chamber 4 and previously compressed by the compression section 3. Such a turbomachine 1 is said to be of the tractor type. Alternatively, the turbomachine 1 may be of the pusher type. In this case, the fan section may be arranged at the rear of the turbomachine 1 , downstream of the turbine section 5.

[0028] For example, turbomachine 1 is a USF type turbomachine, in which propeller 2 is unducted. This makes it possible to increase the bypass ratio significantly without being penalized by the mass of the casings or nacelles intended to surround the propeller or fan blades.

[0029] In such a turbomachine 1 with an unducted propeller 2, the fan section comprises a rectifier 6 in addition to the propeller 2. The rectifier 6 makes it possible to straighten the air stirred by the propeller 2, in order to improve the thrust efficiency. Alternatively, the fan section may comprise a second counter-rotating propeller, or a second counter-rotating fan providing the same function as the rectifier 6.

[0030] In the present application, upstream and downstream are defined with respect to the direction of flow of gases through the turbomachine 1 in operation. The X axis corresponds to the axis of rotation around the rotor of the propeller 2. The axial direction corresponds to the direction of the X axis and a radial direction is a direction perpendicular to this X axis and passing through it. Furthermore, the circumferential (or tangential) direction corresponds to a direction perpendicular to the X axis and not passing through it. 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.

[0031] The rectifier 6 comprises a hub 8 and a blading 6a, the blading 6a being able to be defined as comprising the hub 8. The hub 8 is fixedly mounted relative to a casing 9 of the turbomachine 1. The hub 8 is therefore non-rotating. The blading 6a comprises a plurality of blades 7, each extending substantially radially relative to the axis X from the hub 8. The blading 6a is therefore static.

[0032] Each of the blades 7 can be fixed, that is to say be mounted fixedly on the hub 8 or be variable-pitch, that is to say be mounted pivotally about a pitch axis Y on the hub 8, the pitch axis Y being fixed relative to the axis X.

[0033] The blades 7 are generally fixed when the fan 2 is shrouded, the hub 8 then corresponding to the shell of an intermediate casing interposed between different portions of the compression section 3, typically between the casing of a low-pressure compressor and the casing of a high-pressure compressor. When the blades 7 are variable-pitch, the rectifier 6, in particular the blade 6a, comprises an actuating mechanism 10 making it possible to modify the pitch angle of the blades 7 in order to adapt the performance of the turbomachine 1 to the different flight phases. In particular, the hub 8 comprises an attachment 11 (or pivot) for each blade 7 and a body 12, the attachment 11 being rotatably mounted relative to the body 12. More precisely, the attachment 11 is rotatably mounted about the pitch axis Y in a housing provided in the body 12, by means of rolling elements such as balls.Each blade 7 is mounted in the hub 8 by means of such a fastener 11.

[0034] The blades 7 being identical, in order to facilitate the description, the following description describes one of the blades 7.

[0035] The blade 7 comprises a blade 13 with an aerodynamic profile suitable for being placed in an air flow when the turbomachine 1 is in operation in order to generate lift, as well as a blade root 14 configured to be fixed to the hub 8, for example via the attachment 11. The blade 13 is not shown in FIG. 2.

[0036] The blade 7 is shaped so as to define a lower surface 7a, an upper surface 7b, a leading edge and a trailing edge. The leading edge is configured to extend opposite the flow of gases entering the turbomachine 1. It corresponds to the front part of an aerodynamic profile which faces the air flow and which divides the air flow into an lower surface flow and an upper surface flow. The trailing edge corresponds to the rear part of the aerodynamic profile, where the lower and upper surfaces flow meet.

[0037] The blade 7 may comprise a composite material comprising a fibrous reinforcement embedded in a matrix, for example a polymer matrix. The fibrous reinforcement may comprise woven or knitted three-dimensional fibrous arrangements. It is furthermore made such that it comprises warp threads which extend continuously both inside the airfoil blade portion 13 and inside the blade root portion 14. Alternatively, the fibrous reinforcement may comprise laminated two-dimensional fibrous arrangements. The fibers of the fibrous reinforcement 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 (thermosetting, thermoplastic or elastomer) or a carbon matrix.For example, the matrix comprises a plastic material, typically a polymer, for example epoxy, bismaleimide or polyimide.

[0038] The fiber reinforcement may in particular comprise two skins, which are connected to each other and extend generally opposite each other from an outer end of the blade 7, or blade tip, to the blade root 14. In particular, the skins are connected at the blade tip over the entire chord of the blade 7, at the leading edge and at the trailing edge. The skins may be monolithic and be made in a single piece from a fiber preform with varying thickness. Alternatively, a first skin may be formed from a first portion of the fiber reinforcement in order to form the lower surface 7a and a second skin may be formed from a second portion of the fiber reinforcement in order to form the upper surface 7b, the first and second skins of the reinforcement then being connected, for example in proximity from the blade tip 7 to the blade root 14.

[0039] Alternatively, the blade 7 is made of metal. The straightener 6, and particularly the blade 6a, comprises a first jaw 15a and a second jaw 15b each mounted on the hub 8, for example on the attachment 11. The first and second jaws 15a and 15b are arranged on either side of the blade root 14. For example, the first jaw 15a is arranged on the intrados side 7a of the blade root 14, and the second jaw 15b is arranged on the extrados side 7b of the blade root 14. The first and second jaws 15a and 15b are configured to transmit forces between the blade 7 and the hub 8.

[0040] The rectifier 6, and particularly the vane 6a, may comprise, for the same blade 7, several first jaws 15a and several second jaws 15b. For example, the blade 7 may comprise at least two first jaws 15a and two second jaws 15b. Taking into account the usual length (chord) of the stator blades 7, the blade 7 may comprise at most four first jaws 15a and four second jaws 15b. For example, the blade 7 comprises three first jaws 15a and three second jaws 15b. The first jaws 15a and the second jaws 15b may then be identical to each other or not.

[0041] In all embodiments with several first and second jaws 15a, 15b, the first and second jaws 15a, 15b are arranged so as to extend along the blade 7 between the leading edge and the trailing edge, i.e. along the chord of the blade 7. The first jaws 15a are for example arranged on the intrados side 7a of the blade root 14 and the second jaws 15b on the extrados side 7b of the blade root 14. In other words, the first jaws 15a, respectively the second jaws 15b, are substantially aligned along the blade root 14 between the leading edge and the trailing edge. Preferably, two first jaws 15a or two second jaws 15b successively along the blade root 14 are then spaced apart by a constant distance, in order to uniformly distribute the absorption of forces along the blade root 14.In order to distribute the force absorption evenly, the first and second jaws 15a and 15b are preferably arranged symmetrically with respect to the blade root 14, i.e. opposite each other.

[0042] The first jaw 15a is fixedly mounted on a surface of the hub 8, for example on an external surface 11a of the attachment 11. More particularly, the first jaw 15a may be mounted on an external surface of the hub 8, for example on the external surface 11a of the attachment 11, being monolithic with this external surface. For example, the first jaw 15a is thus mounted on the external surface 11a of the attachment 11 and is monolithic with this external surface 11a, in order in particular to reduce the number of parts by avoiding the need for specific fixing means. Alternatively, the first jaw 15a is fixed on a surface of the hub 8 such as the external surface 11a of the attachment 11, by means of fixing means such as bolts.

[0043] The second jaw 15b, as well as the first jaw 15a when it is not monolithic with the external surface 11a of the attachment 11, is preferably made of titanium or inconel (registered trademark) (nickel and chromium alloy), but can simply be made of any suitable metal. When the first jaw 15a is monolithic with the attachment 11 which is metallic, the first jaw 15a is made of the same metal.

[0044] The second jaw 15b is mounted on the hub 8, for example on the attachment 11, being movable relative to the first jaw 15a between a first configuration in which the second jaw 15b extends at a distance from the blade root 14, and a second configuration in which the second jaw 15b is configured to press the blade root 14 against the first jaw 15a. The second jaw 15b is for example mounted movable on the external surface 11a of the attachment 11.

[0045] The first and second jaws 15a and 15b may both be mounted on the same surface of the hub 8, for example on the external surface 11a of the attachment 11.

[0046] A recess 11 b may be formed in a surface of the hub 8, into which the blade root 14 and the second jaw 15 b are at least partially inserted. In other words, at least a portion of the blade root 14 and a portion of the second jaw 15 b are configured to be inserted into the recess 11 b. In particular, the portion of the blade root 14 configured to be inserted into the recess 11 b comprises an inner end of the blade root 14.

[0047] Those skilled in the art will understand that the recess 11b may be configured to at least partially receive the blade root 14 and the second jaw 15b and / or the first jaw 15a. Similarly, the jaw 15b is described here as movable and the first jaw 15a is described as fixed, however this is not limiting, and in other embodiments, the first jaw 15a may be movable in a manner analogous to the description herein of the mobility of the second jaw 15b, just as the second jaw 15b may be fixed.

[0048] The recess 11 b extends radially inward from an outer surface of the hub 8 in contact with the blade root 14. For example, the recess 11 b is formed in the outer surface 11 a of the fastener 11. The recess 11 b comprises dimensions and a shape corresponding to dimensions and a shape of the portions of the blade root 14 and the second jaw 15 b configured to be inserted into the recess 11 b, so as to participate in the immobilization of the blade root 14 and the second jaw 15 b when inserted into the recess 15 b. In other words, the dimensions and the shape of the recess 11 b are chosen to enclose the portions of the blade root 14 and the second jaw 15 b inserted into the recess 11 b.

[0049] Each of the first and second jaws 15a, 15b comprises a bearing face 16a, 16b configured to be pressed against the blade root 14, a base 17a, 17b configured to be mounted on the hub 8 and a rib 18a, 18b connecting the bearing face 16a, 16b and the base 17a, 17b.

[0050] The bearing face 16a, 16b (in the second configuration) extends radially and is arranged opposite the blade root 14. Alternatively, the bearing face 16a, 16b (in the second configuration) can extend at a non-zero angle relative to the radial direction. In any case, the bearing face 16a of the first jaw 15a is in contact with the blade root 14, for example on the intrados side 7a of the blade root 14, and the bearing face 16b of the second jaw 15b is arranged on the extrados side 7b of the blade root 7b, such that when the second jaw 15b is arranged according to the second configuration, the bearing face 16b is in contact with the extrados side 7b of the blade root 14.In the case where the bearing face 16a, 16b extends at a non-zero angle relative to the radial direction, the first and second jaws 15a, 15b take up, by progressive contact, the radial and curvature forces of the blade root 14 during operation of the turbomachine and therefore the bending of the blade root 14 under the effects of the air in contact with the blade 13.

[0051] The base 17a, 17b of each of the jaws 15a and 15b rests on the hub 8, for example on the attachment 11, and more particularly on the external surface 11a of the attachment 11. The base 17a, 17b extends tangentially from the bearing face 16a, 16b in a direction opposite to the blade root 11. The base 17a is fixedly mounted on the hub 8, for example on the external surface 11a of the attachment 11, while the base 17b of the second jaw 15b is configured to slide on the hub 8, for example on the external surface 11a of the attachment 11. Each of the bases 17a, 17b thus comprises a free tangential edge 19a, 19b opposite the bearing face 16a, 16b. In other words, the free tangential edge 19a, 19b of the base 17, 17b is opposite the blade root 14.

[0052] The rib 18a, 18b of each of the jaws 15a, 15b connects the free tangential edge 19a, 19b of the base 17a, 17b to an external edge 20a, 20b of the bearing face 16a, 16b. The rib 18a, 18b thus makes it possible to reinforce the jaws 15a, 15b, in order to increase the volume of forces that can be transmitted by the jaws 15a and 15b between the blade 7 and the hub 8. The rib 18a, 18b may be straight or curved. In one embodiment, the rib 18a, 18b is at least a simple bar.

[0053] To allow the mobility of the second jaw 15b on the hub 8, for example on the attachment 11, the second jaw 15b may comprise an insertion portion 23 and the hub 8, for example the attachment 11, may comprise a groove 24 accessible from an external surface of the hub 8 such as the external surface 11a of the attachment 11, and in particular accessible from the surface of the hub 8 in contact with the second jaw 15b. The groove 24 is then configured to receive the insertion portion 23 and guide the second jaw 15b between the first and second configurations.

[0054] The insertion portion 23 of the second jaw 15b may be arranged on the base 17b and extend radially from the base 17b inwards. The groove 24 then comprises an end 24a arranged so that when the insertion portion 23 is arranged in the groove 24 at this end 24a, the second jaw 15b, and more particularly its bearing face 16b, is in contact with the blade root 14 partially inserted in the recess 11b. In practice, the end 24a is the end of the groove 24 closest to the blade root 14. For example, the insertion portion 23 is arranged on the base 17b in the radial extension of the bearing face 16b, in order to increase the contact surface with the blade root 14. In this case, the end 24a of the groove 24 is in contact and opens onto the recess 11b, and the insertion portion 23 corresponds to the portion of the second jaw 15b configured to be inserted into the recess 11b.

[0055] Thus, when the second jaw 15b is in the second configuration, the insertion portion 23 is at the end 24a of the groove 24, while when the second jaw 15b is in the first configuration, the insertion portion 23 is in any other position along the groove 24.

[0056] The insertion portion 23 and the groove 24 may have a dovetail section, in order to hold the portion 23 in the groove 24.

[0057] In order to maintain the second jaw 15b in the second configuration according to which the second jaw 15b presses the blade root 14 against the first jaw 15a, and more particularly against the bearing face 16a of the first jaw 15a, the blade may comprise at least one means 25a for fixing the second jaw to the hub 8 and / or at least one means 25b for fixing the second jaw to the first jaw 15a.

[0058] The fastening means 25a, 25b may for example comprise bolts or screws. The fastening means 25a is for example configured to fix the second jaw 15b to the attachment 11. For example, the fastening means 25a partially passes through the base 19b and the attachment 11 radially.

[0059] The fixing means 25b can pass tangentially through the blade root 14 and the bearing faces 16a, 16b to secure the first and second jaws 15a, 15b opposite each other.

[0060] Each of the jaws 15a, 15b may comprise at least one free edge that is chamfered or curved (in other words, has a fillet) in order to gradually transmit the forces to the blade 7 and to the hub 8, and thus not to create a stress break. For example, each of the external edges 20a, 20b of the bearing faces 16a, 16b is chamfered or curved (has a fillet), as is each of the free tangential edges 19a, 19b.

[0061] By chamfered is meant that the thickness of the free edge 19a, 19b, 20a, 20b is gradually reduced towards its free end. The free end of the free edge 19a, 19b, 20a, 20b is therefore thinner.

[0062] Although what has been described previously has been with reference to the blading 6a of a rectifier 6 of a USF-type turbomachine 1, the present disclosure also applies to any static blading 6a (i.e., non-rotating) of a turbomachine 1, whether it is a rectifier blading 6a of a fan or a propeller 2, a rectifier blading 6 of the compression section 3, or a distributor blading 6 of the turbine section 5. By way of example, as has been explained, the turbomachine 1 may in particular be a USF-type turboprop comprising an unducted propeller 2, in which case the static blading 6 is unducted and extends downstream of the propeller 2. In another example, the turbomachine 1 may be a turbojet comprising a ducted fan, in which case the static vane 6 may correspond to a shrouded rectifier extending downstream of the fan which is known by the English designation of “outlet guide vane”.

[0063] The blade 7 was thus defined relative to the axis X of the rotor of the propeller 2 associated with the static blading 6a, but depending on the case, the axis X could have been defined in a similar manner relative to the axis of rotation of the fan for a fan rectifier, to the axis of rotation of the compressor rotor for a compression section rectifier 3 or even to the axis of rotation of the turbine rotor for a turbine section distributor 5 on which it is intended to be mounted.

[0064] Likewise, for simplification, the present description has been described in the case of variable-pitch blades 7 whose root is mounted in the hub 8 by means of an attachment 11. However, the present description is not limited to this configuration and applies identically to a fixed blade 7 whose root is mounted directly on the body 12 of the hub 8.

[0065] In order to facilitate reading of the description of the process which follows, we consider here that the blade is made of composite material.

[0066] In a first step E1, the blade root is produced.

[0067] More precisely, a fibrous blank of the two skins is produced, for example by weaving or knitting. The two skins are monolithic from the head to the foot of the blade 14. Alternatively, the two skins can be woven separately in two or three dimensions, then joined during firing (co-firing). The geometry of the foot of the blade 14 being simplified (the foot of the blade being radially straight), weaving is facilitated, as is the detection of anomalies during weaving, and the cutting of warp and weft threads which are not woven throughout the blank (to create variations in thickness or unlinking, which is not the case in the shape of the foot of the blade proposed in the disclosure).

[0068] The fiber blank is placed in a mold having a housing having the shape of the final molded part, namely the blade 13 and the blade root 14, this operation also being simplified due to the geometry of the blade root 14. Indeed, the absence of forming angles which could induce poor fiber placement simplifies and shortens the operation, in particular by reducing the risk of forming anomalies. Material, generally plastic, is injected into the mold so as to impregnate the fiber reinforcement of the skins. The injection of the matrix can be carried out by an injection technique of the RTM or VARRTM type. 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.

[0069] The plastic is then heated to cause polymerization of the plastic, for example by crosslinking. For this purpose, the mold is placed in an oven.

[0070] The part obtained is then demolded and then, optionally, machined to remove excess lengths and obtain a part having the desired shape, despite possible shrinkage of the fibers of the fiber reinforcement during polymerization of the plastic material. The sacrificial thicknesses are in particular machined to obtain the reference surfaces of the blade root 14. Through passages are also machined in the skins to receive the fixing system 25a. If necessary, counterbores are also machined around the through passages.

[0071] In a second step E2, the hub 8 and the first jaw 15a are produced, for example monolithically, so that the jaw 15a is mounted on the hub 8, for example on the external surface 11a of the attachment 11. The monolithic nature of the first jaw 15a with the hub 8 allows the first jaw 15a to be more rigid, which makes it possible to reduce the dimensions of this first jaw 15a in order to be less bulky. Optionally, the recess 11b is made in the hub 8, for example in the external surface 18a at the level of the bearing face 16a of the first jaw 15a.

[0072] In a third step E3, the blade root 14 is placed on the hub 8 against the first jaw 15a. In the case where the reinforcement 11b has been provided in the hub 8, the blade root 14 is placed in the recess 11b so as to bear against the bearing face 16a of the first jaw 15a.

[0073] In a fourth step E4, the second jaw 15b is attached and fixed to the hub 8 so as to press the blade root 14 against the first jaw 15a. More precisely, the insertion portion 23 is placed in the groove 24, and the second jaw is moved from the first configuration to the second configuration in which the second jaw 15a presses the blade root 14 against the first jaw 15a. In other words, the second jaw 15b is moved to a position in which the insertion portion 23 is located at the end 24a of the groove 24. Then, the fixing means 25a and 25b are arranged in order to maintain the second jaw in the second configuration. This presentation thus makes it possible to reduce the tangential and radial size at the blade root, while preserving the integrity of the blade root by ensuring the absorption of forces between the blade 7 and the hub 8.

Claims

CLAIMS 1. Blade (7) of a static blade (6a) of a turbomachine (1), comprising: - a dawn foot (14); - a hub (8) configured to receive the blade root (14) and fix it relative to the blading (6a); - a first jaw (15a) mounted on the hub (8); and - a second jaw (15b) mounted on the hub (8) movable relative to the first jaw (15a) between a first configuration in which the second jaw (15b) extends at a distance from the blade root (14), and a second configuration in which the second jaw (15b) presses the blade root (14) against the first jaw (15a).

2. Blade (7) according to claim 1, wherein a recess (11 b) is formed in a surface (11 a) of the hub (8), the second jaw (15 b) and the blade root (14) being at least partially inserted into the recess (11 b).

3. A blade (7) according to claim 2, wherein dimensions and a shape of the recess (11 b) correspond to dimensions and a shape of the portions of the blade root (14) and the second jaw (15 b) which are inserted into the recess (11 b) so as to immobilize the blade root (14) and the second jaw (15 b).

4. Blade (7) according to one of claims 1 to 3, in which the first jaw (15a) is mounted on a surface (11a) of the hub (8) while being monolithic with the surface (11a).

5. Blade (7) according to one of claims 1 to 4, in which the hub (8) comprises a fastener (11) mounted to move relative to the hub (8), the first jaw (15a) and the second jaw (15b) being mounted on a surface (11a) of the fastener (11).

6. Blade (7) according to one of claims 1 to 5, in which each of the jaws (15a, 15b) comprises a bearing face (16a, 16b) configured to be in contact with the blade root (14), a base (17a, 17b) configured to be mounted on the hub (8) and a rib (18a, 18b) connecting the bearing face (16a, 16b) and the base (17a, 17b).

7. A blade (7) according to claim 6, wherein the second jaw (15b) further comprises an insertion portion (23) extending radially inward from the base (17b) and the hub (8) further comprises a groove (24) configured to receive the insertion portion (23) and guide the second jaw (15b) between the first and second configurations.

8. Blade (7) according to claim 7, in which the insertion portion (23) and the groove (24) have a dovetail section.

9. Blade (7) according to one of claims 1 to 8, in which all or part of the ends (19a, 19b, 20a, 20b) of the first and second jaws (15a, 15b) are chamfered or have a fillet.

10. Blade (7) according to one of claims 1 to 9, further comprising at least one first means (25a) for fixing the second jaw (15b) to the hub (8) and at least one second means (25b) for fixing the second jaw (15b) to the first jaw (15a), the at least one second means (25) passing through the blade root (14).

11. Method of assembling a blade according to any one of claims 1 to 10, comprising the following steps: - produce (E1) a blade foot (14); - producing (E2) a hub (8) and a first jaw (15a), the first jaw (15a) being mounted on the hub (8); - place (E3) the blade root (14) in the hub (8) against the first jaw (15a); and - attach and fix (E4) a second jaw (15b) on the hub (8) so as to press the blade root (14) against the first jaw (15a).

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