Blade comprising a composite material structure and associated manufacturing process

Abstract

The present invention relates to a blower blade (7) comprising a blade foot (17) and a bracket (9) configured to receive the blade foot (17) with an adjustable fit and to fix it to a blower hub (6). The bracket (9) comprises a plate (22) configured to be fixed to the blower hub (6), two walls (23) extending from the plate (22), and at least one fastening member (24). The fastening member (24) comprises a rod extending through openings (25, 27) formed through the walls (23) of the bracket (9) and the blade foot (17) so as to fix the blade foot (17) in the bracket (9). Figure for the abstract: Fig. 3

Description

Description Title of the invention: Blade comprising a material structure composite and associated manufacturing process FIELD OF INVENTION

[0001] The invention relates to a blower (or propeller) blade of a propulsion system which may include a structure made of composite material.

[0002] The invention relates more particularly, but not exclusively, to a blade intended for use in an unshod aircraft engine fan rotor (such as an "Open Rotor" type engine, i.e., one whose fan is not streamlined, featuring two rotating propellers or a USF type engine for " Unducted Single Fan » featuring a moving blade and a fixed blade or a turbo- propulsion system featuring a single-propeller architecture) or in a rotor wind turbine. STATE OF THE ART

[0003] — The design of blower blades requires taking into account constraints antagonists.

[0004] — On the one hand, the sizing of these blades must allow for aerodynamic performance optimal naming (maximize efficiency and provide thrust while minimizing losses). Improving the aerodynamic performance of the fan tends to towards an increase in the bypass ratio (or BPR) implies an increase in the external diameter and therefore the span of these blades.

[0005] On the other hand, it is also necessary to guarantee resistance to stresses mechanical forces that can be exerted on these blades while limiting their acoustic signature.

[0006] — The advantage of engines with an unfaired fan (or propeller) is that the diameter of the The blower is not limited by the presence of a fairing, so it is possible to designing an engine with a high bypass ratio, and consequently a reduced fuel consumption.

[0007] — Thus, in this type of engine, the blower blades may have a large-scale.

[0008] — It has been proposed to make these blades out of metallic material. If the blades are made of material Metallic materials have good mechanical resistance, however they present the disadvantage of having a relatively large mass.

[0009] = In order to reduce this mass, it is desirable to be able to manufacture these blades in composite material. For this purpose, the composite material of the blower blades includes a fibrous reinforcement made by three-dimensional weaving densified by a polymer matrix. Where appropriate, the blades may include skins made of The blade is made of composite material and defines its aerodynamic profile, with a spar housed within the skins forming the blade's root and strut. This spar is configured to increase the blade's stiffness (particularly torsional stiffness) and resist the vibrational excitations experienced by the blade during the various phases of flight. However, it appears that manufacturing such blades from composite material can be complex from a process perspective. Furthermore, open-fan engines typically include a mechanism to adjust the blade pitch angle, thus adapting the thrust generated by the fan to different flight phases. To achieve this, the blades are attached at their root by a bracket that rotates relative to the hub around a pitch axis. These brackets are therefore subjected to significant centrifugal forces during fan rotation, as well as intense vibrational excitation that varies depending on the flight phase and blade pitch angle. This vibration damages the lower part of the root (fretching). However, the vibrations at the blade root and the centrifugal forces are difficult to manage, especially at low engine speeds, and can damage the fan blades. Description of the invention One aim of the invention is to remedy the aforementioned disadvantages, by proposing a blower blade, in particular made of composite material, and a blower comprising such blades, in particular with variable pitch, in which vibrations in the blade root are limited or even eliminated, particularly at low speeds, and which is also simple to manufacture. For this purpose, according to a first aspect of the invention, a blower comprising: - a wingtip with a base and two opposite faces extending along the intrados and extrados of the wingtip; and - a bracket configured to receive the blade foot with adjustment and to fix it to a blower hub. The bracket comprises a plate configured to be fixed to the blower hub and two walls extending from the plate and at least one fastening member. The walls each extend opposite a corresponding face of the blade foot and the fastening member comprises a rod extending through holes formed through the walls and the blade foot so as to fix the blade foot in the bracket. Some preferred but not exhaustive characteristics of dawn according to the first aspect are the following, taken individually or in combination: - The attachment comprises two fixing elements, each fixing element comprising a rod extending through dedicated holes formed in the walls and the blade foot so as to fix the paddle foot onto the attachment; - at least one fastening element includes a bolt; - the bottom of the blade is of a complementary shape to a face opposite the plate; - the base of the blade is in direct contact with the plate; - the bottom of the paddle foot and the plate are essentially flat; - each wall of the attachment has an internal face configured to come into contact with the opposite face of the blade foot, the internal faces of the attachment and the opposite faces of the blade foot being of complementary shape; - the blade foot is flared towards the bottom, the inner face of the attachment walls being inclined in a complementary way towards the plate; and / or - the attachment is metallic and the blade is made of a composite material comprising a fibrous reinforcement and a matrix in which the fibrous reinforcement is embedded. According to a second aspect, the invention proposes a blower comprising a hub and blades conforming to the first aspect extending radially from the hub, each blade being mounted to rotate relative to the hub by means of a respective attachment. According to a third aspect, the invention proposes a propulsion system comprising a blower according to the second aspect and an aircraft comprising at least one propulsion system according to the third aspect. DESCRIPTION OF THE FIGURES 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: [Fig.1] Fig.1 schematically represents an example of an engine including an unfaired fan: [Fig.2] Fig.2 illustrates an example of an aircraft comprising engines conforming to an embodiment of the invention; [Fig.3] Fig.3 schematically represents a fan blade and an actuation mechanism to change the angle of the fan blades, in which the fan blade has been shown in partial section to show the spar, a filler piece and the structural reinforcement. [Fig. 4] [Fig. 4] is a partial perspective view of an example of a fastener according to one embodiment of the invention; and [Fig.5] The [Fig.5] is a partial and perspective view of an example of a blower blade according to an embodiment of the invention which can be fixed using the attachment of [Fig.4] on a blower hub. Across all figures, similar elements bear identical references. DETAILED DESCRIPTION OF THE INVENTION In [Fig.1], the engine 1 shown is an "Open Rotor" type engine, in a configuration commonly referred to as "pusher" (i.e. the unfaired fan is placed at the rear of the power generator with an air inlet located on the side, to the right in [Fig.1]). Engine 1 comprises a nacelle 2 intended to be attached to the fuselage of an aircraft 100 and a fan 3 (or propeller), which is shown here unfaired. The fan 3 comprises two counter-rotating fan rotors 4 and 5. In other words, when engine 1 is running, the rotors 4 and 5 are driven in rotation relative to the nacelle 2 around the same axis of rotation X (which coincides with a main axis of the engine), in opposite directions. In the example illustrated in [Fig. 1], motor 1 is an "Open Rotor" type motor in a "pusher" configuration with counter-rotating fan rotors. However, the invention is not limited to this configuration. The invention also applies to "Open Rotor" type motors in a "puller" configuration (i.e., the fan is placed upstream of the power generator with an air inlet located before, between, or just behind the two fan rotors). The invention also applies to motors with different architectures, such as an architecture comprising a fan rotor with movable blades 7 and a fan stator with fixed blades, or a single fan rotor. The fan 3 may also be enclosed and include variable-pitch blades. The invention is also applicable to turboprop type architectures (comprising a single fan rotor), as well as to wind turbine rotors. In this application, the axis of rotation of the rotors 4 and 5 of the blower 3 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. Each blade 7 is mounted to rotate relative to the hub 6 around a respective Y-axis: this Y-axis extends in a generally radial direction relative to the X-axis. Finally, internal (respectively, inner) and external (respectively, outer) are used with reference to a radial direction such that the inner part or face of an element is closer to the X-axis than the outer part or face of the same element. Blade 7 will thus be defined in relation to the X axis of the rotor on which it is intended to be mounted and its Y axis of alignment. The term "blower" will also be used in the rest of the description, although the invention applies mutatis mutandis to a propeller. In [Fig.1], each blower rotor 4, 5 comprises a hub 6 (or blade hub) mounted rotatably relative to the nacelle 2 and a plurality of blades 7 fixed to the hub 6. The blades 7 extend substantially radially relative to the axis of rotation X of the rotor. As illustrated in [Fig. 3], the fan 3 further includes an actuation mechanism 8 for collectively adjusting the pitch angle of the blades 7 of each rotor to adapt engine performance to different flight phases. For this purpose, each blade 7 includes a bracket 9 (or blade hub 7) located at the blade root 17. The bracket 9 is rotatably mounted relative to the hub 6 around a pitch axis Y. More precisely, the bracket 9 is rotatably mounted within a housing in the hub 6 by means of screws 11 extending radially within a plate 22 of the bracket 9. Reference may be made to document FR2943314 for further details on this assembly. The actuation mechanism 8 may be conventional. For example, the actuation mechanism may conform to the mechanism described in document WO2013050704. The fan blade 7 comprises a blade root 17 configured to be inserted into the hub 6 via the attachment 9, a blade 18 suitable for flow orientation, and a strut corresponding to the area of ​​the blade 7 extending between the hub 6 outlet (at the bearing surfaces) and the blade 18. The blade 18 has an upper surface, a lower surface, a leading edge, and a trailing edge. The leading edge, as is known, is configured to extend in relation to the flow of gases entering the engine 1. It corresponds to the forward part of an airfoil that faces the airflow and divides the airflow into an upper surface and an upper surface flow. The trailing edge, for its part, corresponds to the rear part of the airfoil, where the upper and lower surface flows meet. The blade foot 17 has a bottom 19 and opposite faces 20, 21 extending in the continuation of the intrados and extrados of the blade 7. In what follows, these faces 20, 21 will be called the intrados face 20 and the extrados face 21 of the foot 17, respectively (even though these faces are not traversed by an airflow). To improve the resistance of the blade 7 to centrifugal forces, the attachment 9 comprises the plate 22 configured to be fixed to the hub 6 of the blower, two walls 23 extending radially from the plate 22 and at least one fastening member 24 configured to fix the blade foot 17 to the attachment 9. The walls 23 of the attachment 9 each extend opposite a corresponding face 20, 21 of the blade foot 17. The fastening member 24 comprises a rod extending through openings 25, 27 formed through the walls 23 and the blade foot 17 respectively so as to fix the blade foot 17 in the attachment 9. The combination of the rigid walls 23 and the fixing device(s) (fixing the blade foot 17 to the walls 23) makes it possible to reduce or even eliminate vibrations at low The system in the blade foot 17 is secured by fitting the blade foot 17 into the attachment 9. The clamping of the blade foot 17 by the fixing elements 24 also prevents friction, which could damage the blade foot 17. Preferably, in order to prevent the blade 7 from pivoting relative to the attachment 9, at least two fastening members 24 are mounted in corresponding holes 25, 27 formed in the walls 23 and in the blade foot 17. The attachment of the blade foot 17 using two fastening members 24 also allows for redundancy in the event of cracking of the attachment 9 and / or the blade foot 17. The openings 25, 27 are preferably through and the fixing member 24 includes for example bolts. To effectively hold the blade 7, the fastener 9 conforms to the shape of the foot 17 with a clamping action. For this purpose, the inner faces of the plate 22 and the walls 23 that are opposite the blade foot 17 have a shape complementary to the intrados 20 and extrados 21 faces and the bottom 19 of the blade foot 17, respectively. Preferably, the inner faces of the fastener 9 are in surface contact with the opposite intrados 20 and extrados 21 faces and the bottom of the blade foot 17. In one embodiment, a majority, or even all, of the surface of the bottom 19 and the intrados 20 and extrados 21 faces of the blade foot 17 are in surface contact with the fastener 9. In one embodiment, the bottom 19 of the blade foot 17 is flat. The inner face opposite the plate 22 is then also substantially flat. Alternatively, the bottom 19 of the blade foot 17 can be curved, in which case the inner face of the plate 22 is concave and has a substantially complementary concave shape to make surface contact with the bottom 19. The intrados 20 and extrados 21 faces of the blade foot 17 can be substantially flat and can diverge from the bearing area (corresponding to the lower limit of the blade strut 7) towards the bottom 19. The internal faces of the walls 23 then have a shape complementary to that of the intrados 20 and extrados 21 faces of the foot 17 in order to contribute to the resistance to centrifugal forces of the blade 7. Alternatively, in order to further improve resistance to centrifugal forces, the intrados 20 and extrados 21 faces can be substantially flat and parallel (or possibly diverge slightly) over a first part of the height of the foot 17, from the area of ​​the supports to a limit 26 extending to a first height of the foot 17, then the foot 17 can flare out further to the bottom 19 over a second part of the height of the foot 17 so as to form a shoulder. Thus, over the first part of the height of foot 17, the intrados 20 and extrados 21 faces can form an angle between 0° and 10° with the Y-axis up to the limit 26, then diverge at an angle between 20° and 45° with the Y-axis from the limit 26 to the bottom 19 of the foot over the second height of foot 17. The internal faces of the walls 23 present then a complementary form to that of the intrados 20 and extrados 21 faces and present a break line from which their inclination increases in order to follow the shape of the blade foot 17. The orifices 25 are formed in the walls 23 of the attachment 9 so as to extend substantially circumferentially with respect to the axis X, that is substantially perpendicular to the alignment axis Y. The orifices 27 are formed in the blade foot 17, in the extension of the orifices 25 formed in the walls 23 of the attachment 9. In a first embodiment, the shape of the plate 22 is adapted to allow its insertion and retention in the housing 10, for example by means of screws and / or bolts. For example, the plate 22 may comprise an outer face, on which the pin 16 of the actuation mechanism 8 can be fixed, and a substantially circular periphery to allow the plate 22 to rotate around the alignment axis Y. In a second embodiment, the plate 22 can be directly integrated into the hub 6. The blower 3 is then fixed (no variable adjustment of the blades 7 is possible). The thickness and material of the mounting plate 22 and the walls 23 of the attachment 9 are chosen to ensure mechanical support of the blower blade 7. For example, the attachment 9 can be made of titanium or steel, with the walls 23 and the mounting plate then having a minimum thickness of 5 mm, for example a thickness between 5 and 20 mm. Preferably, the walls 23 and the plate 22 of the fastener 9 are monolithic and manufactured as a single piece. The walls 23 extend substantially radially from the plate 22. The plate 22 is also globally symmetrical with respect to a plane normal to the plate and passing through the center of the walls 23. The thickness of the walls 23 can be substantially continuous along their entire length. The blade 7 is made of a composite material comprising a fibrous reinforcement obtained by three-dimensional weaving and a matrix in which the fibrous reinforcement is embedded. The fiber reinforcement can be formed from a single-piece fiber preform obtained by three-dimensional or multi-layer weaving with varying thickness. It may include carbon, glass, aramid, and / or ceramic fibers. The matrix encapsulating the fiber reinforcement is typically a plastic material, usually a polymer such as epoxy, bismaleimide, or polyimide, or a carbon matrix. The blade 7 is then formed by molding using a vacuum resin injection process such as RTM (Resin Transfer Molding) or VARRTM (Vacuum Resin Transfer Molding). The fibrous reinforcement is woven in such a way that it comprises warp threads that extend continuously both inside the aerodynamically profiled blade section 18- dynamic and inside the part of the foot of the blade 17. Advantageously, the attachment 9 can be attached to the blade foot 17 after its manufacture and machining, which significantly simplifies the manufacturing process compared with prior art blades made of composite material. The shape of the blade foot 17 is also simplified.

Claims

Demands

1. Aubc (7) of blower comprising: - a paddle wheel foot (17) having a base (19) and two faces (20, 21) opposites extending along the continuation of an intrados and a extrados of dawn (7); and - a fastener (9) configured to receive the foot with adjustment of the blower (17) and fix it to a blower hub (6); the blade (7) being characterized in that the attachment (9) comprises a plate (22) configured to be fixed to the blower hub (6), two walls (23) extending from the plate (22) and at least one fastening member (24), the walls (23) each extending opposite a face (20, 21) corresponding to the foot of the paddle (17), and in that the fixing organ (24) comprises a rod extending through orifices (25, 27) formed through the walls (23) and the foot of the paddle (17) so as to fix the foot dawn (17) in the attachment (9).

2. Blade (7) according to claim 1 wherein the attachment (9) comprises two fastening members (24), each fastening member (24) comprising a rod extending through dedicated orifices (25, 27) formed in the walls (23) and the foot of the blade (17) so as to fix the foot dawn (17) on the attachment (9).

3. Blade (7) according to claim 1 or 2, wherein the at least a fastening element (24) includes a bolt.

4. Dawn (7) according to any one of claims 1 to 3, wherein the bottom (19) of the dawn (7) is of complementary shape to a face opposite the platinum (22).

5. Blade (7) according to any one of claims 1 to 4, wherein the foot The dawn (17) is in direct contact with the plate (22).

6. Dawn (7) according to any one of claims 4 and 5, wherein the bottom (19) The blade foot (17) and the plate (22) are substantially flat.

7. Blade (7) according to any one of claims 1 to 6, wherein each wall (23) of the fastener (9) has an internal face configured for come into contact with the face (20, 21) opposite the foot of the dawn (17), the internal faces of the attachment (9) and the faces opposite the blade foot (17) being of complementary form.

8. Blade (7) according to claim 7, wherein the blade foot (17) is flared towards the bottom (19), the inner face of the walls (23) of the attachment (9) being inclined in a complementary manner in the direction of the platinum (22).

9. Blade (7) according to any one of claims 1 to 8, wherein the attachment (9) is metallic and the blade (7) is made of a composite material comprising a fibrous reinforcement and a matrix in which the fibrous reinforcement.

10. Blower (3) comprising a hub (6) and blades (7) conforming to one of claims 1 to 9 extending radially from the hub (6), each blade (7) being mounted to rotate relative to the hub (6) by via a respective attachment (9).