Propeller blade with hollow composite root

Abstract

The invention relates to a propeller blade (10) for a propeller engine, made of a composite material, comprising a matrix-densified fibrous reinforcement, comprising a root (12) and an aerodynamic profile (11) in the direction of its spanwise direction (DL). The fibrous reinforcement includes a fibrous preform having a three-dimensional weave, the fibrous preform having a root preform portion and an aerodynamic profile preform portion. The fibrous preform comprises a partition defining a recess forming a cavity (14) extending both into the root (12) and into the aerodynamic profile (11). A spar (130) is present in the cavity (14), the spar including an aerodynamic profile forming portion (131) positioned in a first portion (142) of the cavity (14) and a root forming portion (132) positioned in a second portion (141) of the cavity (14). The root (12) has a rotationally symmetrical shape.

Description

Technical Field

[0001] The present invention relates to the field of propeller blades for aircraft, such as those present on turboprop engines. Background Art

[0002] Propeller blades for turboprop engines are usually made of metal materials. Although metal propeller blades have good mechanical strength, they still have the disadvantage of being relatively heavy.

[0003] In order to obtain lighter propeller blades, it is known to produce propeller blades made of composite materials, in other words by producing structural components with a matrix-densified fiber reinforcement.

[0004] Document US 2013 / 0017093 describes the production of a propeller blade from a fiber structure having an aerodynamic profile, into which is introduced a portion of a spar, one end of which is prolonged by a raised portion forming the root of the propeller blade.

[0005] New engine generations require a more compact blade root. This need stems from the need to be able to pivot the blade about its vertical axis in order to adapt its angle of attack to the flight conditions (blades with variable pitch). This need, coupled with the fact that the blade must be incorporated as low as possible on the disk, makes it necessary to significantly reduce the dimensions of this root.

[0006] To this end, the roots of the new generation of blades have an axisymmetric or substantially axisymmetric shape and reduced dimensions compared to prior art roots such as described in document US 2013 / 0017093, these roots extending over the entire width of the lower part of the blade.

[0007] Such axisymmetric or quasi-axisymmetric shapes are more difficult to manufacture from composite materials, particularly when three-dimensional (3D) weaving is used to form the fiber reinforcement of the blade.

[0008] Furthermore, the mechanical loads to which the new generation roots are subjected impose additional constraints. More specifically, in addition to the mechanical traction and bending loads normally encountered (caused by centrifugal forces and object impact, respectively), the new generation roots may be incorporated into the disk of the rotor using a metal shell, which creates additional mechanical loads in circumferential compression. Summary of the invention

[0009] It is therefore desirable to propose a solution for producing aircraft propeller blades made of composite materials which have a compact root and are able to withstand various mechanical loads.

[0010] To this end, the invention proposes a method for manufacturing a propeller blade for a turboprop engine, the propeller blade being made of a composite material, including a matrix densified fiber reinforcement, the method comprising:

[0011] - producing a fiber blank as a single piece by three-dimensional weaving, the fiber blank having a flat shape extending in a longitudinal direction and a transverse direction, respectively, the longitudinal direction corresponding to the span direction of the propeller blade to be manufactured, the transverse direction corresponding to the chord direction of the propeller blade to be manufactured, the fiber blank comprising a root portion and an aerodynamic profile portion, the aerodynamic profile portion extending from the root portion in the longitudinal direction and between the leading edge portion and the trailing edge portion in the transverse direction (D T )extend,

[0012] - shaping said fiber blank so as to obtain a single-piece fiber preform having said aerodynamic profile portion forming an aerodynamic profile preform and said root portion forming a root preform, and

[0013] - densifying said fiber preform by means of a matrix so as to obtain an intermediate part made of composite material having a fiber reinforcement constituted by said fiber preform and densified by said matrix, said intermediate part comprising an aerodynamic profile portion and a root portion,

[0014] It is characterized in that the root portion of the fiber blank includes a spacer, which defines an inner recess extending both into the root portion of the fiber blank and into the aerodynamic profile portion, the inner recess opening at the lower part of the fiber blank, and shaping the fiber blank includes: inserting a wing spar in the inner recess, the wing spar including an aerodynamic profile shaping portion positioned in the aerodynamic profile portion of the fiber blank and a root shaping portion positioned in the root portion of the fiber blank so as to form an aerodynamic profile preform portion and a root preform portion, respectively, and the method also includes: after the densification step, machining the root portion of the intermediate component made of composite material along a determined radius so as to form a propeller blade, the propeller blade including a root having a rotationally symmetrical shape and an aerodynamic profile.

[0015] Thus, the method of the present invention makes it possible to produce a propeller blade having a composite root which is both compact and fully suitable for withstanding the various mechanical loads mentioned above. More specifically, the fiber reinforcement portion of the root is produced by 3D weaving and has a rotationally symmetrical shape which is connected to the fiber reinforcement portion of the aerodynamic profile at its center. Thus, a more compact composite root than the prior art is obtained, which generally extends over the entire width of the lower part of the aerodynamic profile. In this composite root, there are yarns oriented in the spanwise direction of the blade, such as warp yarns, which, in combination with 3D weaving, give it good mechanical strength in traction and bending. In addition, in the root composite material, there are yarns oriented in the chordwise direction of the blade, such as weft yarns, which give it good circumferential compressive mechanical strength.

[0016] Furthermore, the rotationally symmetrical shape of the root is compatible with the integration of propeller rotation or variable pitch systems.

[0017] By inserting the spar in the fiber reinforcement, wherein the root portion is formed integrally with the aerodynamic profile portion (in other words woven in one piece), a very good mechanical strength of the entire component is ensured, in particular with respect to the forces to which the root portion may be exposed.

[0018] According to one aspect of the invention, the spacers present in the root portion of the fiber blank and in the root shaped portion of the spar have a width in the transverse direction that is greater than the machining radius of the root portion of the intermediate part made of composite material. This enables the entire spar to pass through the root portion of the fiber blank.

[0019] According to another aspect of the method of the present invention, the spar is made of a composite material, including a matrix densified fiber reinforcement, or the spar is made of a metallic material.

[0020] According to another aspect of the method of the present invention, shaping the fiber blank further comprises inserting a shaping part made of a rigid honeycomb material around the aerodynamically contoured portion of the spar.

[0021] According to another aspect of the method of the present invention, shaping the fiber blank further comprises injecting expansion material around the aerodynamically contoured portion of the spar.

[0022] Another object of the invention is a propeller blade for a turboprop engine, made of composite material, comprising a matrix-densified fiber reinforcement, the propeller blade comprising in its spanwise direction a root and an aerodynamic profile, the root and the aerodynamic profile extending in the chordwise direction between a leading edge and a trailing edge, the fiber reinforcement comprising a fiber preform with three-dimensional weaving, the fiber preform having a root preform portion and an aerodynamic profile preform portion, the root preform portion being present in the root, the aerodynamic profile preform portion being present in the aerodynamic profile, the root and the aerodynamic profile preform portions being connected to each other by three-dimensional weaving, characterized in that the fiber preform comprises a partition defining a recess, the recess forming a cavity extending both into the root and into the aerodynamic profile, a spar being present in the cavity, the spar comprising an aerodynamic profile shaping portion positioned in a first portion of the cavity and a root shaping portion positioned in a second portion of the cavity, and the root of the propeller blade having a rotationally symmetrical shape.

[0023] According to one aspect of the propeller blade of the present invention, the root shaped portion of the spar is exposed at the leading edge and the trailing edge of the root of the propeller blade, and the remaining portion of the root shaped portion of the spar is covered by the fiber preform.

[0024] According to another aspect of the propeller blade according to the present invention, the spar is made of a composite material, including a matrix densified fiber reinforcement, or the spar is made of a metal material.

[0025] The invention also relates to an aerospace engine comprising a plurality of propeller blades according to the invention and to an aircraft comprising at least one such engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram illustrating 3D weaving of a fiber blank for manufacturing a blade,

[0027] Figure 2 is an enlarged scale cross-sectional view of the yarn layer assembly along the weft direction, which shows Figure 1 The root portion of the blank is formed along the partition of section II-II,

[0028] Figure 3 It shows Figure 1 A three-dimensional schematic diagram of the forming of the root preform part and the aerodynamic profile preform part in the fiber blank,

[0029] Figure 4is an exploded perspective schematic diagram showing an injection tool and placement of a fiber preform in the injection tool according to an embodiment of the present invention,

[0030] Figure 5 It shows Figure 4 A three-dimensional schematic diagram of a closed injection tool.

[0031] Figure 6 is a three-dimensional schematic diagram of an intermediate component made of a composite material obtained according to an embodiment of the present invention,

[0032] Figure 7 It is machining Figure 6 Schematic perspective view of a blade made of composite material obtained after removing the root part of the intermediate component. DETAILED DESCRIPTION

[0033] The invention is generally applicable to various types of propeller blades used in aircraft engines. The invention has an advantageous, but not exclusive, application in large-sized propeller blades intended to be incorporated in oscillating or variable pitch systems. Such propeller blades are usually provided with a so-called "cylindrical" root, in other words, a root having a rotationally symmetrical shape and having a good resistance to traction, bending and circumferential compression forces. In particular, the blades according to the invention may constitute: blades of closed moving wheels (such as fan blades) or blades of open moving wheels (for example, in so-called "open rotor" aircraft engines).

[0034] In the remainder of the description, the exemplary embodiment is described with respect to a blade of a turboprop engine. However, the exemplary embodiment is also applicable to an aircraft propeller blade.

[0035] Figure 1 A fiber blank 100 for forming a fiber preform of a blade to be produced is shown highly schematically.

[0036] like Figure 1 As schematically illustrated in FIG. 1 , the fiber structure blank 100 is obtained by three-dimensional (3D) weaving in a known manner using a jacquard-type loom, on which a bundle of warp yarns 101 or strands have been arranged into multiple layers of warp yarns of several hundred yarns per layer, the warp yarns being connected by weft yarns 102. The fiber structure blank 100 is woven into a single piece, the blank being woven in the longitudinal direction D L and the transverse direction D T Extension, longitudinal direction D L Corresponding to the span direction between the lower part 100c and the upper part 100d of the blade to be manufactured, the transverse direction D TCorresponding to the chord direction between the leading edge 100a and the trailing edge 100b of the blade to be manufactured, the blank comprises: an aerodynamic profile portion 111 which defines two faces 111e and 111f for forming the suction side and the pressure side of the blade respectively; and a root portion 112 for subsequently forming the blade root and extending in the longitudinal direction D L The aerodynamic profile blank 111 extends to the outside and in the transverse direction D T The upper edge is recessed inwardly from the leading edge 100a and the trailing edge 100b.

[0037] Here, the term "three-dimensional weaving" or "3D weaving" refers to a weaving method in which at least some of the warp yarns are connected to the weft yarns over multiple weft yarn layers, such as "interlock weaving". Here, the term "interlock" weaving refers to a weaving in which each layer of weft yarns connects multiple layers of warp yarns and all yarns in the same weft yarn column have the same movement in the weaving plane.

[0038] Other types of known three-dimensional weaving can be used, such as those described in document WO 2006 / 136755, the content of which is incorporated herein by reference. In particular, this document describes the production of a fiber-reinforced structure of a component such as a blade by a single-piece weaving, the fiber-reinforced structure having a first type of core weaving and a second type of skin weaving, which can give such a component the desired mechanical and aerodynamic properties.

[0039] In particular, the fiber blank according to the invention may be woven from carbon fibers or ceramic yarns (eg silicon carbide).

[0040] During the weaving of the fiber blank, its thickness and width vary, and a certain number of warp yarns are not woven, which makes it possible to define the desired continuously variable profile and thickness of the blank 100. An example of progressive 3D weaving is described in document US2006 / 257260, in particular, this weaving enables the thickness of the blank to vary between a first edge for forming the leading edge and a second edge for forming the trailing edge and having a smaller thickness.

[0041] According to the invention, during weaving, a separator 106 is created between two consecutive warp yarn layers inside the fiber blank 100. The separator 106 extends in a plane parallel to the surface of the fiber blank and extends over the area of ​​the separator defined by the contour 106a, which locally separates the fiber blank 100 into two woven parts 113 and 114. In the longitudinal direction D L In the embodiment, the spacer 106 passes through the root portion 112 of the fiber blank 100 and partially penetrates into the aerodynamic profile portion 111 of the fiber blank 100. In addition, the spacer 106 is disposed between the leading edge 100a and the trailing edge 100b of the blank 100 in the transverse direction D. TIn other words, the partition 106 is not opened at the leading edge 100a and the trailing edge 100b so as to retain the connection portions 105 and 107 adjacent to the leading edge 100a and the trailing edge 100b, respectively. In addition, the partition 106 is open at the lower portion 100c. Therefore, the partition 106 forms an inner recess 140 that can be entered through the lower portion 100c.

[0042] Figure 2 A 3D weave pattern with an interlocking weave of the blank 100 is schematically shown. Figure 2 is the warp yarn cross section of a portion of the blank 100 including the region of the separator 106 ( Figure 1 In this example, the blank 100 includes: a substantially longitudinal direction D L The 8-layer warp yarn 101 is stretched. Figure 2 In the embodiment, the eight layers of warp yarns are connected in the connection areas 105 and 107 of the fiber blank 100 by weft yarns T1 to T8, which are substantially connected in the transverse direction D T At the separator 106, the woven portion 113 comprises 4 layers of warp yarns 101 connected together by 4 weft yarns T1 to T4, while the woven portion 114 comprises 4 layers of weft yarns forming the yarn layer group 109 connected by 4 weft yarns T5 to T8.

[0043] In other words, the fact that weft yarns T1 to T4 do not extend into the warp yarn layer of woven portion 114 and weft yarns T5 to T8 do not extend into the warp yarn layer of woven portion 113 ensures the partition 106 that separates woven portions 113 and 114 .

[0044] Once the weaving is completed, the unwoven yarns present around the fiber blank 100 are cut to extract the blank and then the root portion of the blank is shaped. In the example described here, the shaping of the root portion 112 is achieved by separating the woven portions 113 and 114 and introducing the spar 130 into the inner recess 140 formed by the spacer 106, as shown in FIG. Figure 3 The spar 130 includes an aerodynamic profile shaping portion 131 positioned in an upper portion or base 140a of a recess 140 present in the aerodynamic profile portion 111 of the fiber blank 100. The spar 130 also includes a root shaping portion 132 positioned in a lower portion or starting portion 140b of the recess 140 present in the root portion 112 of the fiber blank 100. The recess 140 is at its lower portion 140b and in the transverse direction D T Extends above width l 140 , the width l 140 Greater than the final diameter of the propeller blade root to be produced, as described below. Width l 140 With fiber blank 100( Figure 1 ) in the width l of the separator 106 106 Correspondingly. This width is necessary in order to allow the aerodynamic profile shaping portion 111 to pass through the lower portion 140b of the recess 140. The root shaping portion 132 of the spar 130 is in the transverse direction D T The upper part has an elongated shape so as to adapt to the width l of the recess in the lower part 140b of the recess. 140 , in particular in order to control the retention of the shape of the preform in the injection mold.

[0045] The spar 130 may be made of various materials. In particular, it may be made of a composite material, including a fiber reinforcement obtained by three-dimensional weaving or two-dimensional fiber layer stacking and densified by a matrix. The spar may also be made of a metallic material.

[0046] In the example described here, a shaped part 150 made of a rigid cellular material (eg a rigid foam) is positioned around the aerodynamically profiled portion 131 of the spar.

[0047] Therefore, if Figure 4 As shown in FIG. , a fiber preform 200 is obtained, which has a longitudinal direction D L The aerodynamic profile preform part 211 and the root preform part 212 having a convex shape and a concave portion 240 (including the spar 130) are provided on the wing. The aerodynamic profile preform part 211 is provided between the leading edge part 211a and the trailing edge part 211b along the transverse direction D T extend.

[0048] Then, the fiber preform is densified. The densification of the fiber preform for forming the fiber reinforcement of the part to be manufactured includes: filling the holes of the whole or part volume of the preform with the material constituting the matrix. This densification is carried out in a known manner (i.e. according to the liquid method (CVL)). The liquid method involves: impregnating the preform with a liquid composition containing a precursor of the matrix material. The precursor is usually in the form of a polymer, such as a high-performance epoxy resin optionally diluted in a solvent. The preform is placed in a mold closed in a sealed manner, the mold having a recess identical to the final blade shape to be molded. The mold is then closed, and the matrix precursor liquid (e.g., resin) is injected into the entire recess to impregnate all fiber parts of the preform.

[0049] The conversion of the precursor into the matrix (ie its polymerization) is carried out by thermal treatment, generally by heating the mould, after removal of any solvent and crosslinking of the polymer, the preform always remaining in the mould having a shape corresponding to that of the part to be produced.

[0050] In the case of forming a carbon ceramic matrix, the thermal treatment comprises pyrolyzing the precursor in order to convert the matrix into a carbon or ceramic matrix, depending on the precursor used and the pyrolysis conditions. For example, the ceramic liquid precursor (particularly SiC) can be a polycarbosilane (PCS), polytitanium carbosilane (PTCS) or polysilazane (PSZ) resin, while the carbon liquid precursor can be a resin with a relatively high coke content, such as a phenolic resin. In order to achieve the desired degree of densification, several consecutive cycles from impregnation to thermal treatment can be performed.

[0051] According to one aspect of the invention, in particular in the case of forming an organic matrix, the densification of the fiber preform can be carried out by the well-known resin transfer molding (RTM) method. According to the RTM method, the fiber preform is placed in a mold having the external shape of the part to be produced. Thermosetting resin is injected into the internal space of the mold including the fiber preform. A pressure gradient is usually established in the internal space between the location where the resin is injected and the orifice for removing the resin, so as to control and optimize the impregnation of the preform by the resin.

[0052] like Figure 4 As illustrated in the figure, here, the process of injecting a liquid matrix precursor composition into a fiber structure and converting it into a matrix is ​​carried out in an injection tool 300, which includes a first shell 310 and a second shell 320, the first shell 310 including at its center: a first mold 311, which partially corresponds to the shape and size of the blade to be produced, and the second shell including at its center: a second mold 321, which partially corresponds to the shape and size of the blade to be produced.

[0053] like Figure 5 As illustrated in FIG. 3 , once the tool 300 is closed, the first die 311 and the second die 321 of the first shell 310 and the second shell 320 together define an inner volume 301 having the shape of the blade to be produced and in which the fiber preform 200 is placed. The compaction of the fiber preform 200 can be carried out with the tool 300 closed in order to obtain a determined fiber content in the preform. In this case, the compaction pressure is applied to the shells 310 and 320, for example by a press. The compaction of the fiber preform can also be carried out in a separate tool before the preform is introduced into the injection tool.

[0054] The tool 300 also comprises means for injecting a liquid matrix precursor and means for converting this precursor into a matrix. More precisely, in the example described here, the first housing 310 of the tool 300 comprises an injection port 313 for injecting the liquid matrix precursor composition into the fiber preform, while the second housing comprises an exhaust port 323 for interacting with a pumping system for placing the tool under vacuum and removing air during injection. The injection tool 300 also comprises a lower part 340 and an upper part 350, between which the first housing 310 and the second housing 320 are placed, the lower part 340 and the upper part 350 being equipped with a heating device ( Figure 5 not shown).

[0055] Once the tool 300 is closed, the molding of the blade is performed by impregnating the preform 200 with a thermosetting resin (polymerized by heat treatment). For this purpose, the well-known resin transfer molding (RTM) method is used. According to the RTM method, a resin 360 (for example a thermosetting resin) is injected into the internal space occupied by the preform 200 via the injection port 313 of the first shell 310. The port 323 of the second shell 320 is connected to the exhaust duct ( Figure 6 323). This configuration enables a pressure gradient to be established between the lower portion of the preform 200 (where the resin is injected) and the upper portion of the preform located near the port 323. In this way, the resin 360 injected mainly at the lower portion of the preform will gradually impregnate the entire preform by flowing therein until the excess resin is discharged through the discharge port 323. Of course, the first shell 310 and the second shell 320 of the tool 300 may include a plurality of injection ports and discharge ports, respectively. The RTM process may also be performed under vacuum (VA-RTM).

[0056] For example, the resin used may be an epoxy resin with a temperature grade of 180°C. Resins suitable for the RTM method are well known. Preferably, they have a low viscosity to facilitate their infusion into the fibers. The choice of the temperature grade and / or chemical nature of the resin depends on the thermomechanical stresses that the component must withstand. Once the resin has been infused throughout the reinforcement, its polymerization is carried out by a thermal treatment according to the RTM method.

[0057] The densification method described above makes it possible to produce, from the fiber preforms of the invention, propeller blades mainly made of composite materials with an organic matrix (CMO), a carbon matrix (C / C) and a ceramic matrix (CMC).

[0058] After injection, polymerization and demoulding, as Figure 6As illustrated in , an intermediate component 20 made of composite material having a fiber reinforcement consisting of a matrix-densified fiber preform 200 is obtained, the intermediate component 20 comprising an aerodynamic profile portion 21 and a root portion 22 .

[0059] Then, from the radius R determined by U The intermediate component 20 made of composite material is machined to have a root portion 22, which determines the radius R U Limited machining profile C U , so as to form a root portion having a rotationally symmetrical shape. Then, the root portion 22 is machined to remove the root portion 22 existing in the machining profile C U The outer material forms a root having a rotationally symmetrical shape. Figure 6 As can be seen in FIG. 1 , a portion of the root shaped portion 132 of the spar 130 extends to the machined profile C U Therefore, the machining here includes: U The outer densified fiber preform is also present in the contour C U Part of the root-shaped portion 132 of the outer spar 130 is removed.

[0060] Finally, the blade is trimmed to remove excess resin and the chamfers are machined. Since the part is molded, no other machining is required as it conforms to the required dimensions.

[0061] like Figure 7 As illustrated in FIG. 1 , a blade 10 is obtained, which is formed of a matrix-densified fiber reinforcement, and which includes, in its lower part, a root 12 formed by a machined root preform portion 212 and an airfoil 11 formed by an airfoil preform portion 211 of a fiber preform 200. The blade 10 has a leading edge 11a and a trailing edge 11b, which correspond to the leading edge 211a and trailing edge 211b portions of the fiber preform 200, respectively. The root portion 12 includes: a cavity 14 formed by an inner recess 240 of the fiber preform 200, the cavity 14 including a spar 130 bonded to the inside of the cavity 14, an aerodynamic profile forming portion 131 of the spar 130 existing and bonded in a first portion 142 of the cavity 14, the first portion corresponding to an upper portion 140a of the recess 140 existing in the aerodynamic profile portion 111 of the fiber blank 100, and a root forming portion 132 of the spar 130 existing and bonded in a second portion 141 of the cavity 14, the second portion corresponding to a lower portion 140b of the recess 140 existing in the root portion 112 of the fiber blank 100.

[0062] like Figure 71 , it can be seen that the root forming portion 132 of the spar 13 is exposed at the leading edge 12a and the trailing edge 12b of the root of the propeller blade, the remainder of the root forming portion of the spar being covered by the densified fiber preform. This local exposure of the spar at the root of the propeller blade is caused by machining the root portion 22 of the intermediate part 20 with a diameter that is smaller than the excess width of the partition 106 at the portion of the fiber blank 100 that is used to form the root of the propeller blade. However, due to the elongated shape of the root forming portion 132 of the spar 130, most of the outer periphery of the root 12 is formed by the root preform portion 212 of the fiber preform 200. By retaining most of the fiber reinforcement on the outer periphery of the root 12, the strength of the propeller blade is improved in this area that is subject to large bending forces due to the aerodynamic loading of the propeller blade. Since the fiber reinforcement has a continuous three-dimensional weave from the root to the aerodynamically profiled tip, it is ideally suited to transferring local forces to the rest of the propeller blade, thereby increasing its mechanical strength.

[0063] In the above example, a shaped part made of a rigid honeycomb material is positioned around the aerodynamic profile shaped portion of the spar. However, the use of such a shaped part is optional and the spar can have a shape suitable for filling the entire volume of the inner recess present in the aerodynamic profile portion. The use of an additional shaped part made of a rigid honeycomb material makes it possible to reduce the overall mass of the propeller blade. It is also possible to produce the shaped part in situ around the aerodynamic profile shaped portion by injecting an expansion material. In this case, a soluble filler element, such as a salt core, is temporarily positioned in the fiber preform before the matrix is ​​injected. Once the intermediate part has been produced, in other words after the fiber preform has been densified, the filler element is removed and the expansion material is injected into the vacated volume.

Claims

1. A method for manufacturing a propeller blade (10) for a turboprop engine, made of a composite material, including a matrix densified fiber reinforcement, the method comprising: A single fiber blank (100) is produced by three-dimensional weaving, wherein the fiber blank has a plurality of longitudinal directions (D L ) and transverse direction (D T ), the longitudinal direction corresponds to the span direction between the lower part (100c) and the upper part (100d) of the propeller blade to be manufactured, the transverse direction corresponds to the chord direction of the propeller blade to be manufactured, the fiber blank (100) comprises a root part (112) and an aerodynamic profile part (111), the aerodynamic profile part extending from the root part along the longitudinal direction (D L ) and extends along the transverse direction (D) between the leading edge portion (100a) and the trailing edge portion (100b) T )extend, shaping the fiber blank (100) to obtain a single-piece fiber preform (200) having the aerodynamic profile portion (111) forming an aerodynamic profile preform (211) and the root portion (112) forming a root preform (212), and Densifying the fiber preform (200) by means of a matrix to obtain an intermediate component (20) made of composite material, the intermediate component having a fiber reinforcement consisting of the fiber preform (200) and densified by the matrix, the intermediate component comprising an aerodynamic profile portion (21) and a root portion (22), The method is characterized in that the root portion (112) of the fiber blank (100) comprises a spacer (106), the spacer defining an inner recess (140) extending both into the root portion and into the aerodynamic profile portion of the fiber blank, the inner recess (140) opening at a lower portion (100c) of the fiber blank, shaping the fiber blank (110) comprising: inserting a spar (130) in the inner recess (140), the spar comprising an aerodynamic profile shaping portion (131) positioned in the aerodynamic profile portion (111) of the fiber blank (100) and a root shaping portion (132) positioned in the root portion (112) of the fiber blank, so as to form an aerodynamic profile preform portion (211) and a root preform portion (212), respectively, and the method further comprises: after the densification step, cutting the fiber blank along a determined radius (R U ) subjecting the root portion (22) of the intermediate component (20) made of composite material to a machining step in order to form a propeller blade (10) comprising a root (12) having a rotationally symmetrical shape and an aerodynamic profile (11).

2. The method according to claim 1, wherein: The spacers (106) present in the root portion (112) of the fiber blank (100) and the root forming portion (132) of the spar (130) are oriented in the transverse direction (D T ) has a machining radius (R) greater than that of the root portion (22) of the intermediate component (20) made of composite material. U ) Large width (L 106 ).

3. The method according to claim 1 or 2, wherein: The spar (130) is made of a composite material, including a matrix densified fiber reinforcement, or the spar (130) is made of a metallic material.

4. The method according to any one of claims 1 to 3, wherein: Shaping the fiber blank (100) further comprises inserting a shaping part (150) made of a rigid honeycomb material around the aerodynamically contoured portion (131) of the spar (130).

5. The method according to any one of claims 1 to 3, wherein: Shaping the fiber blank (100) further includes injecting expansion material around the aerodynamically contoured portion (131) of the spar (130).

6. A propeller blade (10) for a turboprop engine, the propeller blade being made of a composite material, comprising a matrix-densified fiber reinforcement, the propeller blade having a widthwise direction (D L ) comprises a root portion (12) and an aerodynamic profile (11), wherein the root portion and the aerodynamic profile are connected along a chordwise direction (D) between a leading edge (11a) and a trailing edge (11b) T ), the fiber reinforcement comprising a fiber preform (200) having three-dimensional weaving, the fiber preform having a root preform portion (212) and an aerodynamic profile preform portion (211), the root preform portion (212) being present in the root (12), the aerodynamic profile preform portion (211) being present in the aerodynamic profile (11), the root and aerodynamic profile preform portions being connected to each other by the three-dimensional weaving, characterized in that The fiber preform comprises a spacer defining an inner recess (140) opening at the root preform portion (212), the recess forming a cavity (14) extending both into the root (12) and into the aerodynamic profile (11), a spar (130) being present in the cavity (14), the spar comprising an aerodynamic profile shaping portion (131) positioned in a first portion (142) of the cavity (14) and a root shaping portion (132) positioned in a second portion (141) of the cavity, and the root (12) of the propeller blade having a rotationally symmetrical shape.

7. The propeller blade according to claim 6, wherein: The root shaped portion (132) of the spar (130) is exposed at the leading edge (12a) and the trailing edge (12b) of the root (12) of the propeller blade, and the rest of the root shaped portion of the spar is covered by the fiber preform.

8. The propeller blade (30) according to claim 6 or 7, wherein: The spar (130) is made of a composite material, including a matrix densified fiber reinforcement, or the spar (130) is made of a metallic material.

9. An aircraft engine comprising a plurality of propeller blades according to any one of claims 6 to 8.

10. An aircraft comprising at least one engine according to claim 9.

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