Fan or propeller blade for aircraft turbine and method of manufacturing the same

Abstract

A fan or propeller blade (1) for an aircraft turbine, the blade being made of composite material and comprising a blade (2) and a base (3), the base being formed by the longitudinal ends (41) of a spar (4), the spar being formed by a fiber reinforcement formed by three-dimensionally woven threads, and a portion (42) of the spar extending inside the blade (2), the blade (2) having an aerodynamic profile defined by a skin (5) formed by woven threads and surrounding the portion of the spar, the spar (4) and the skin (5) being embedded in a polymer resin, characterised in that the portion (42) of the spar comprises protruding longitudinal reinforcements (6) which together delimit a space (8) for receiving a longitudinal insert (7) formed by a honeycomb material.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft turbomachines, such as turbojets or turboprops, and more particularly to a propeller fan blade for a turbomachine and a method for manufacturing a propeller fan blade for a turbomachine. Background Art

[0002] The prior art includes, inter alia, documents US-A1-2013 / 039774 and EP-A2-2500263.

[0003] In a known manner, the aircraft turbomachine, in the assumption of a shrouded architecture, comprises, from upstream to downstream in the direction of the airflow, a fan, a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine and a low-pressure turbine. The rotor of the low-pressure compressor is driven by the rotor of the low-pressure turbine, and the rotor of the high-pressure compressor is driven by the rotor of the high-pressure turbine.

[0004] A turbomachine comprises rotor blades which rotate within a housing. This is, for example, the case of a fan blade of a turbomachine which is surrounded by a retaining housing. Such a blade generally comprises a root and a blade, the root comprising lateral faces which are connected to the blade and which serve to form a bearing surface in a mounting housing of a rotor disk.

[0005] The blades are designed to have good mechanical strength and to reduce the noise emitted by the blades during operation in order to optimize the aerodynamic performance of the turbine.

[0006] Typically, in order to improve the aerodynamic performance of, for example, the fan module and its blades, the bypass ratio (BPR) of the turbine is increased. This results in an increase in the outer diameter of the blades and the span of the blades. Such a large size can reduce some of the natural modes of these blades, in particular the natural frequencies when the blades are bent. The natural modes of these blades can be enhanced by greatly increasing the thickness of the walls forming the blades. However, this will significantly increase the weight of the blades and the overall size of the turbine.

[0007] In a similar manner, this argument for the dimensioning of the thickness of the fan remains valid in the case of a shrouded architecture (fan blades) or an unshrouded architecture (propeller blades), an architecture with or without a mechanical reducer, or a "pull" (propeller blades located at the front of the turbine) configuration or a "push" (propeller blades located at the rear of the turbine) configuration.

[0008] Typically, the outer surface of the blade (or skin) of a high-chord blade does more mechanical work than the central part of the blade. It is therefore possible to envisage producing so-called "hollow" blades, the central part of which can be made of a lighter material (e.g. foam), thus optimizing the overall mass of the blade. However, this central part does not have any structural rigidity and under extreme operating conditions (e.g. ingestion of solid particles), the integrity of the blade may be seriously affected.

[0009] The present invention proposes a simple, effective and economical solution to this problem. Summary of the invention

[0010] The invention proposes a fan or propeller blade for an aircraft turbine, the blade being made of composite material and comprising a blade and a root, the root being formed by the longitudinal ends of a spar, the spar being formed by a fiber reinforcement formed by three-dimensionally woven threads and having a portion of the spar extending inside the blade, the blade having an aerodynamic profile defined by a skin formed by woven threads and surrounding the portion of the spar, the spar and the skin being embedded in a polymer resin. The portion of the spar comprises protruding longitudinal reinforcements, between which the longitudinal reinforcements define a space for accommodating a longitudinal insert formed of a porous material.

[0011] The longitudinal reinforcements of the invention are made of braided wires similar to the skin of the blade with an aerodynamic profile, allowing to ensure an efficient and uniform transmission of forces between the skin and the spar, without any concentrated areas of constraint or deformation. The blade of the invention, in particular with a large chord length, thus has a lighter overall mass due to the presence of the longitudinal inserts made of porous material and an increased mechanical strength due to the presence of the longitudinal reinforcements made of composite material (fiber reinforcements dense with resin). In fact, the rigidity of the blade is increased to resist shocks or impacts, for example, to resist the forces of bird inhalation.

[0012] The blade according to the invention may include one or more of the following features, either alone or in combination with each other:

[0013] - Each reinforcement is formed by unraveling the threads of the spar; in fact, after each unraveling, in particular of the warp threads of the spar, the weaving thickness of the weft threads increases so as to form an overthickness at the unraveling. Each unraveling and overthickness allows the formation of a 3D woven reinforcement.

[0014] - the transverse thickness of the spar decreases from the root towards the opposite ends of the spar;

[0015] - the skin comprises an at least partial unbending of the soffit and abutment walls separating the blades, in particular at the trailing edge of the skin;

[0016] - the reinforcement is arranged on the soffit side or the dome side of a portion of the spar;

[0017] - the spar comprises two to twelve reinforcements spaced apart from one another;

[0018] - each reinforcement has a variable thickness, in particular between 2 mm and 5 mm;

[0019] - the end forming the root extends outside the skin;

[0020] - the blade comprises a protective element, for example a thermoplastic polyurethane film, located on one of the edges of the blade;

[0021] - the porous material of the longitudinal insert is selected from Polymer foam, aluminum foam, metal honeycomb and / or Type polymer.

[0022] The present invention also relates to a method for manufacturing a blade according to an embodiment of the present invention, the method comprising the following steps:

[0023] a) producing a first fiber preform by three-dimensionally braiding the wires, the first fiber preform being called a "spar preform"; said preform comprising a longitudinal end portion configured to form a blade root and a portion configured to be inserted inside a blade;

[0024] b) producing a second fiber preform by three-dimensional weaving or braiding the threads, the second fiber preform being called a "skin preform"; said skin preform being configured to form an aerodynamic profile;

[0025] e) arranging the spar preform within the skin preform;

[0026] f) Positioning the preform in a mould and then injecting a thermosetting resin to obtain the blade.

[0027] According to the present invention, before step e) and step f), the method comprises the following steps:

[0028] a2) in step a), a plurality of longitudinal stiffeners are formed on said portion of the spar and spaces are defined between the stiffeners,

[0029] c) production of longitudinal inserts of porous material,

[0030] d) inserting the insert into the corresponding space of the spar preform.

[0031] Advantageously, in step a2), the reinforcement is formed by unraveling the warp threads and adding weft threads where the threads are unraveled.

[0032] Preferably, after step f), the method comprises: step g) of trimming the blade to form the final profile of the blade; and / or step h) of bonding a reinforcement to one of the edges of the blade to form the trailing edge and / or leading edge of the blade.

[0033] In particular, step b) of the method comprises a sub-step b2) of producing an unravelling of the warp threads, for example at the trailing edge side of the skin preform. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The invention will be better understood and other details, features and advantages thereof will become more apparent from the following description given by way of non-limiting example and with reference to the accompanying drawings, in which:

[0035] Figure 1 is a schematic front view of a fan blade according to the present invention;

[0036] Figure 2 It is along Figure 1 A schematic cross-sectional view of a vertical plane B of a blade;

[0037] Figure 3A The first embodiment includes a reinforcing member along the Figure 1 A schematic axial cross-sectional view of a blade in a horizontal plane A;

[0038] Figure 3B According to the second embodiment, the reinforcing member is provided along Figure 1 A schematic axial cross-sectional view of a plane A of a blade;

[0039] Figure 4 The method for manufacturing the Figure 1 The consecutive steps of the method of producing a blade; and

[0040] Figure 5 is based on Figure 4 a schematic front view of a spar preform during one of the manufacturing steps of;

[0041] Fig. 6A It is along Figure 5 A schematic axial cross-sectional view of a spar preform in a horizontal plane D with a reinforcement folded;

[0042] Figure 6B yes Fig. 6A A schematic axial cross-sectional view of , wherein the reinforcement is unfolded;

[0043] Figure 7 It is along Figure 5 Schematic cross-sectional view of a vertical plane C of a spar preform.

[0044] In the drawings of this application, the term "vertical direction" is defined as Figure 1 The term "axial" defines the direction of the axis or plane B. Figure 1 The term "lateral" defines a direction perpendicular to the axis or plane A. Figure 1 Extension in the direction of axis A and axis B. DETAILED DESCRIPTION

[0045] The invention is generally applicable to different types of fan or propeller blades used in aircraft turbomachines, such as aircraft turbojets or turboprops. The invention has advantageous, but not exclusive, application in large blades which, due to their size, have a large mass, which has a significant impact on the overall mass of the turbomachine.

[0046] In a conventional manner, in the assumption of a shrouded architecture, the turbomachine comprises, from upstream to downstream (ie in the flow direction of the gas flow), a fan, one or more compressors, a combustion chamber, one or more turbines and nozzles for ejecting the combustion gases leaving the one or more turbines.

[0047] Figure 1 A fan blade 1 for mounting on a turbomachine is shown, comprising: a blade 2 and a root 3 having a structure for forming an aerodynamic profile of the aerodynamic part of the blade, the root being formed by a portion of greater thickness, for example having a bulbous cross section. The aerodynamic profile blade 2 has a curved profile of variable thickness along the axis A between its leading edge 20a and its trailing edge 20b.

[0048] like Figure 2 As shown, the blade 2 comprises a soffit wall 50a and a dome wall 50b, which form the outer skin 5 of the blade. This blade skin 5 can be formed by braided filaments impregnated with a thermosetting resin. A protective element 90 can be added in the region of the leading edge 20a and / or the trailing edge 20b of the blade. The protective element 90 can be a thermoplastic polyurethane film.

[0049] Furthermore, these walls 50a, 50b are spaced apart from one another by the spar 4. The spar 4 comprises a longitudinal end 41 extending outside the skin 5 and forming the blade root 3, and a portion 42 arranged inside the blade skin 5. The thickness of the spar 4 can decrease from the end 41 of the root towards the opposite end 43 of the spar (i.e. in the span direction of the blade). This thickness ( Figure 1 ). This end 43 is arranged at the top of the blade vane 2. Such a spar can be obtained by a fiber preform made of three-dimensional (3D) braided wires. Similarly, the skin 5 can be obtained by three-dimensional braided wires.

[0050] One characteristic of the invention is that the portion 42 of the spar comprises substantially longitudinally projecting stiffeners 6 which delimit between them spaces 8 intended to house longitudinal inserts 7 .

[0051] Figure 3A and 3B Two non-limiting examples of inserts 6 assembled in a receiving space 8 formed between the reinforcements 6 of the spar are shown. The space 8 for receiving the blade may have different geometries, depending on the arrangement of the reinforcements 6 inside the blade. Figure 3A The reinforcement 6 in FIG. 1 extends substantially parallel to the axis B. Figure 3B The reinforcement members in the embodiment are inclined, thereby forming a space 8 having a triangular and trapezoidal axial cross section.

[0052] In the example, the reinforcement 6 is arranged on the soffit face 40a of the spar 4. Alternatively, the reinforcement 6 can also be arranged on the dome face 40b of the spar 4 or on both faces 40a, 40b, depending on the desired application.

[0053] Each spar 4 may have from two to twelve stiffeners 6. The stiffeners 6 are arranged, for example, in a regular ( Figure 3A ) or random ( Figure 3B ) are spaced apart from each other.

[0054] Each reinforcement 6 has a variable thickness for each spar 4. For example, the thickness of the reinforcement 6 may be between 2 and 5 mm, preferably between 3 and 4.5 mm. This thickness is measured in a direction parallel to the axis A and perpendicular to the axis B of the blade ( Figure 1 ).

[0055] The thickness of the skin 5 of the blade may be between 2 and 5 mm, preferably between 3 and 4.5 mm.

[0056] For example, in Figure 4 The successive steps of the method for manufacturing the blade 1 are summarized in FIG.

[0057] In step a), a fiber spar preform 400 is obtained by 3D weaving.

[0058] Figures 5 to 7 A fiber preform 400 intended to form the spar 4 of the blade 1 is shown very schematically.

[0059] In step a1 ), a 3D continuous fiber tape fabric is produced to form a portion 42 of the spar preform. This portion 42 may have a constant or variable thickness.

[0060] The 3D weaving of the spar preform 400 is obtained by means of a jacquard loom on which a bundle of warp threads or strands has been arranged into a plurality of overlapping layers, each layer having several hundred threads (not shown in the figure), the warp threads being bound by weft threads 401 ( Fig. 6A and Figure 6B ). Generally speaking, the meridians are arranged perpendicular to the latitudes.

[0061] In the example shown, the 3D weave is an "interlock" weave pattern. An "interlock" weave refers to a weave pattern in which each layer of weft threads binds several layers of warp threads, with all threads in a single weft column having the same motion within the plane of the pattern.

[0062] Other known types of 3D weaving may be used, such as those described in particular in document WO-A2-2006 / 136755 of the applicant. This document describes in particular the implementation of a fiber reinforcement structure for a component, such as a blade, having a first type of core pattern and a second type of skin pattern by weaving it in a single piece, which allows to simultaneously impart the desired mechanical and aerodynamic properties to this type of component.

[0063] The preform 400 according to the present invention may be woven from carbon fiber threads.

[0064] Since the preform 400 is woven with different thicknesses and widths, not many warp threads are woven, allowing the contour and the desired continuously varying thickness of the preform 400 to be defined. An example of an advanced 3D weaving is described in document EP-A1-1 526 285 of the applicant, which in particular allows the thickness of the preform to be varied between a first edge intended to form the leading edge and a second edge of less thickness intended to form the trailing edge.

[0065] More specifically, in step a2) of weaving, unravelling 403 is produced between successive warp layers in the preform 400. Unravelling refers to areas where the weft threads, which bind the successive warp layers together, do not pass through. Except at the unravelling, the warp layers are bound together by the weft threads of one or more weft threads.

[0066] The unravelling 403 of the warp threads allows, on the one hand, the formation of reinforcements 6 of the spar and, on the other hand, the creation of spaces 8 between these reinforcements 6. These spaces 8 are configured to receive inserts 7 inside the blade.

[0067] More specifically, the spar preform is a flat weave, wherein after each unravel of the warp threads, the weave thickness of the weft threads increases to form an overthickness at the unravel. An overthickness refers to a local area where the weft threads, which bind the successive layers of warp threads together, do not pass through. Thus, each unravel and overthickness allows the formation of a 3D woven reinforcement.

[0068] At the end of 3D weaving, in step a3), the warp and weft threads are cut at the limit of the weaving quality to extract Figure 5 and Fig. 6A The spar preform shown as it emerges from the 3D weave. For example, the excess length of the reinforcement and / or the contour of the spar preform (e.g., leading edge / trailing edge) is cut with a high pressure water jet.

[0069] In step a4), the thread is unwound to allow the over-thickness to be unfolded, thereby revealing Figure 6B and Figure 7 A reinforcement on a spar preform is shown.

[0070] It should be noted that a set of reinforcements per spar can be formed by different 3D weaving patterns, in particular according to the choice of warp and weft interlacing, the number and the position of the reinforcements, so as to reinforce the mechanical strength of the reinforcement through the portion of the spar relative to the desired dimensions of the blade.

[0071] It should be noted that there are several possibilities to weave the paths of the strands relative to the weft threads to produce the portion 42 of the spar preform and the reinforcement 6. Among the possibilities of 3D weaving, the weaving paths of the weft threads relative to the strands can enter through the reinforcement to pass through the portion of the spar preform and leave, or enter through the portion of the spar preform and then leave through the reinforcement, or enter through the reinforcement after passing through the portion of the spar preform and leave through another reinforcement. This allows to propose a blade with variable reinforcements depending on the desired size and stiffness of the blade.

[0072] For example, if all weft threads enter through the spar portion, particularly on the leading edge side of the spar preform, and then exit through the reinforcement, the proportion of weft threads decreases toward the trailing edge of the preform. Conversely, if all weft threads enter through the reinforcement and pass through portions of the spar preform, the proportion of weft threads increases toward the trailing edge of the preform.

[0073] exist Fig. 6A and 6B A non-exclusive 3D interlocking pattern weaving pattern of the preform 400 is shown very schematically in FIG. Specifically, Fig. 6A and 6B Four types of stiffeners 6a, 6b, 6c, 6a' formed by unraveling 403a, 403b, 403c, 403a' warp threads in a spar preform 400 are shown. Fig. 6A shows a braided unfolded reinforcement, while Figure 6BThe deployed reinforcement is shown. In the example shown, different weft threads bind the warp threads to form a portion 42 of the spar having a constant thickness in the direction of the chord, and then the warp threads are untied 403a, 403b, 403c, 403a' at four areas of the portion 42. At each untied, the increase in thickness is achieved by binding the warp threads of the warp layer in the portion 42a, 42b, 42c, 42a' of the spar portion 42 adjacent to the untied 403a, 403b, 403c, 403a' by the weft threads 401a, 401b, 401c. In particular, the two reinforcements 6a, 6a' are woven from the first weft thread 401a, which enters through the reinforcement 6a to pass through the portion 42 and leaves through the reinforcement 6a' (or vice versa). For this purpose, warp threads are added at one of the unravellings 403a, 403a' so that the weft threads 401a can bind these warp threads with the warp threads of the warp layer of the portion 42a, 42a' of the spar and produce a 3D braiding increase. The reinforcement 6b is then braided by a second weft thread 401b, which enters through the reinforcement 6b to pass through the portion 42 and exits through the trailing edge 40b of the spar preform. For this purpose, warp threads are also added at the unravelling 403b so that the weft threads 401b can bind these warp threads with the warp threads of the warp layer of the portion 42b of the spar. According to the example shown, the reinforcement 6c is braided by a third weft thread 401c, which enters through the leading edge 40a of the spar preform to pass through the portion 42 and exit through the reinforcement 6c. For this purpose, the weft thread 401c binds the warp threads of the warp layer of the portion 42c of the spar to produce a braiding increase at the unravelling 403c.

[0074] Figure 7 A front view of a spar preform 400 is shown extending radially from end 41 through portion 42 towards the opposite end 43 of the spar. Furthermore, the preform 400 comprises a blade root 3 added to the end 41 of the spar preform and a blade head 9 fitted to the opposite end 43 of the spar preform.

[0075] Step b) of the manufacturing method allows the production of a fiber skin preform (not shown separately in the figures) intended to form the aerodynamic profile of the blade.

[0076] In the same way as the spar preform 400 described above, the skin preform can be obtained by 3D weaving with the help of a Jacquard type loom, on which a bundle of warp threads has been arranged in multiple layers, several hundred threads per layer, the warp threads being bound by weft threads.

[0077] In step b1), 3D continuous fiber tape weaving is performed to form a skin preform.

[0078] In step b2), the warp threads may be untied, for example, at the trailing edge of the skin preform, so as to partially separate the soffit wall 50a and the dome wall 50b of the skin preform. In particular, this untied allows to facilitate the introduction of the portion 42 of the spar preform 400 into the interior of the skin preform.

[0079] At the end of the 3D weaving, in step b3), the warp and weft threads are cut at the limit of the weaving quality, for example using a pressurized water jet, in order to extract the desired skin preform.

[0080] Before the blade is formed, longitudinal inserts 7 are produced in step c). These inserts 7 are configured to be assembled into the space 8 intended to house the spar preform 400.

[0081] In step c1), the inserts 7 may be machined to have a shape matching the shape of the spaces 8 of the preform 400. These inserts 7 may be produced directly by a mold having the shape of the spaces 8 of the shell, or by a mold of conventional form, and then these inserts are cut to a shape corresponding to the spaces 8 of the shell. The inserts may be made of a honeycomb material, so as not to significantly increase the overall weight of the blade. This honeycomb material may be unstructured (e.g. polymer foam, aluminum foam, etc.) or structured (e.g. metal honeycomb or similar The shape and thickness of the insert are chosen so as to facilitate its placement in the spar preform without damaging the spar preform and without altering the final aerodynamic surface of the blade.

[0082] In step d), the insert 7 is arranged in the space 8 for receiving the spar preform 400. Preferably, this step d) is performed manually by an operator. The tracer can be used to guide and control the correct positioning of the insert in the receiving space of the spar preform without changing the aerodynamic surface of the blade skin.

[0083] In step e), the spar preform 400 incorporating the longitudinal insert 7 is assembled inside the skin preform, for example in the cavity formed by unraveling the threads of the skin preform.

[0084] Once the portion 42 of the spar preform 400 has been arranged in the skin preform, the fiber preform thus formed is polymerized (or densified) in a step f). Preferably, before polymerizing, the trailing edge 20b of the skin preform separated by unraveling is re-stitched.

[0085] The polymerization of the fiber preform can be carried out in a single operation, i.e., once assembled, by polymerizing the spar and skin preforms simultaneously. In this case, these preforms are densified with the same polymer resin (or matrix).

[0086] According to a variant embodiment of the invention, the spar preform may be polymerized alone with a first resin and then introduced as described above into a skin preform, the skin preform then being polymerized with a second resin different from the first resin.

[0087] Furthermore, the spar and skin preforms may be made from strands made from fibers having the same or different properties.

[0088] The polymerization of the fiber preform consists in filling all or part of the volume of the pores of the preform with the material constituting the resin.

[0089] The resin of the composite material constituting the blade can be obtained by resin transfer molding (RTM) technology. According to the RTM technology, as described above, a spar preform with an insert arranged inside the skin preform is placed in a mold, wherein the shape of the blade has an aerodynamic profile. The mold comprising the assembled preform is placed in an oven. Then a thermosetting resin is injected into the mold. Resins suitable for RTM technology are well known, for example, epoxy resins. These resins preferably have a low viscosity to facilitate injection into the fibers. The temperature of the oven and / or the choice of the chemical properties of the resin are determined according to the thermomechanical constraints that the blade must withstand. Once the resin is injected into the entire fiber reinforcement of the preform, the resin is polymerized by thermal treatment according to the RTM technology. After injection and polymerization, the blade is demoulded.

[0090] In step g), the blade is trimmed to remove excess resin and to form the final profile of the blade.

[0091] Finally, in step h), the leading and / or trailing edge reinforcements may be bonded to the respective edges of the blade.A protection element 90 may be glued to the blade, for example a thermoplastic polyurethane film.

[0092] The different steps described above allow obtaining Figure 1 and Figure 2 The fan blade 1 shown. This blade 1 thus comprises a blade 2 with an aerodynamic profile made of composite material (fiber reinforcement densified by a matrix), a spar 4 with reinforcements also made of composite material (fiber reinforcement densified by a matrix) and an insert made of honeycomb material.

[0093] However, the invention is not limited to fan blades of turbines, but can be applied to other shrouded (fan) or unshrouded (propeller) blades of turbines and movable (rotor) or fixed (stator) blades. The blades of the invention can also be applied in the field of wind or water turbines and in the field of renewable energy.

Claims

1. A fan or propeller blade (1) for an aircraft turbine, said blade being made of composite material and comprising a blade (2) and a root (3), said root (3) being formed by the longitudinal end (41) of a spar (4), said spar being formed by a fiber reinforcement formed by three-dimensionally woven wires, and a portion (42) of said spar extending inside said blade (2), said blade (2) having an aerodynamic profile defined by a skin (5) formed by woven wires and surrounding said portion (42) of said spar, said spar (4) and said skin (5) being embedded in a polymer resin, characterised in that The portion (42) of the spar comprises protruding longitudinal stiffeners (6) between which spaces (8) are defined for receiving longitudinal inserts (7) formed of a porous material.

2. The blade according to claim 1, characterized in that The three-dimensionally woven threads of the spar (4) include warp threads and weft threads, wherein the area where the weft threads that bind consecutive warp thread layers together do not pass through is called an untied area (403), and each reinforcement (6) is formed by the untied area (403) of the warp threads of the spar (4) and the weft threads added at the untied area.

3. The blade according to claim 1 or 2, characterized in that: The transverse thickness of the spar (4) decreases from the root (3) towards the opposite ends (43) of the spar.

4. The blade according to claim 1 or 2, characterized in that: The weaving threads of the skin include warp threads and weft threads, and the skin (5) includes an untied area that at least partially separates the soffit wall (50a) and the dome wall (50b) of the blade, and the untied area of ​​the skin is an area where the weft threads that bind the continuous warp thread layers together do not pass through.

5. The blade according to claim 1 or 2, characterized in that: The reinforcement (6) is arranged on the soffit surface (40a) or the dome surface (40b) of the portion (42) of the spar.

6. The blade according to claim 1 or 2, characterized in that: The spar (4) comprises two to twelve reinforcement members (6) spaced apart from each other.

7. The blade according to claim 1 or 2, characterized in that: Each reinforcement member (6) has a variable thickness.

8. The blade according to claim 1 or 2, characterized in that: The end (41) forming the root (3) extends outside the skin (5).

9. The blade according to claim 1 or 2, characterized in that: The blade comprises a protection element (90) located on one of the edges of the blade (2).

10. The blade according to claim 1 or 2, characterized in that: The porous material of the longitudinal insert (7) is aluminum foam or metal honeycomb.

11. The blade according to claim 4, characterized in that The untied region of the skin is located at the trailing edge of the skin.

12. The blade according to claim 7, characterized in that The variable thickness is between 2 mm and 5 mm.

13. The blade according to claim 9, characterized in that The protective element is a thermoplastic polyurethane film.

14. A method for manufacturing a blade (1) according to any one of claims 1 to 13, the method comprising the following steps: a) producing a first fiber preform by three-dimensionally braiding the wire, the first fiber preform being referred to as a "spar preform" (400); the spar preform (400) comprising a longitudinal end (41) configured to form a blade root (3) and a portion (42) configured to be inserted inside a blade (2); wherein step a) comprises the following steps: a2) forming a plurality of longitudinal reinforcements (6) on the portion (42) of the spar preform, and defining spaces (8) between the reinforcements (6); b) producing a second fiber preform by three-dimensionally braiding the wires, said second fiber preform being called a "skin preform"; said skin preform being configured to form an aerodynamic profile; c) producing a longitudinal insert (7) of porous material; d) inserting the insert (7) into the corresponding space (8) of the spar preform (400); e) arranging the spar preform (400) within the skin preform; and f) positioning the spar preform and the skin preform in a mould and then injecting a thermosetting resin to obtain the blade (1).

15. The method according to claim 14, characterized in that The three-dimensional woven wires of the wing spar preform include warp threads and weft threads, wherein the area where the weft threads that bind the continuous warp threads together do not pass through is called an untied area (403). In step a2), the reinforcement (6) is formed by untied area (403) of the warp threads and adding weft threads at the untied area.

16. The method according to claim 14 or 15, characterized in that After step f), the method comprises: step g), trimming the blade to form the final profile of the blade; and / or step h), bonding a reinforcement to one of the edges of the blade to form the trailing edge and / or the leading edge of the blade.

17. The method according to claim 14 or 15, characterized in that The three-dimensional weaving wires of the skin preform include warp threads and weft threads, and step b) of the method includes: sub-step b2) producing an untied area of ​​the warp threads of the skin preform, wherein the untied area of ​​the skin preform is an area where the weft threads that bind consecutive warp thread layers together do not pass through.

18. The method according to claim 17, characterized in that The untied region of the skin preform is produced at the trailing edge side of the skin preform.

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