Propeller blade or airfoil having a root of wound composite material

Abstract

The invention relates to a propeller blade or airfoil (10) for a turboprop engine, made of composite material and comprising a matrix-densified fiber reinforcement, the propeller blade or airfoil being shaped in the longitudinal direction (D L ) includes a root portion (12) and an aerodynamic profile (11). The fiber reinforcement includes a fiber preform (200) in a three-dimensional woven body, which has a root preform portion (121) located in the root portion (12) and an aerodynamic profile portion (211) located in the aerodynamic profile (11), the root preform portion (212) and the aerodynamic profile preform portion (211) being connected to each other by three-dimensional weaving. The root preform portion (212) includes two woven surface layers (2121, 2122) wound around an insert (130).

Description

Technical Field

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

[0002] The blades or airfoils of a turboprop engine are generally made of metal materials. Although blades or propeller airfoils made of metal materials have good mechanical resistance, they also have the disadvantage of being relatively large in mass.

[0003] In order to obtain lighter blades or propeller airfoils, it is known to produce propeller airfoils made of composite materials, ie to produce the structural component by means of a fiber reinforcement densified by a matrix.

[0004] Document US 2013 / 0017093 describes the production of a propeller airfoil based on a fiber structure with an aerodynamic profile, into which is inserted a portion of a spar, one end of which is extended by a bulge forming the root of the propeller airfoil.

[0005] New engine generations require more compact blade or airfoil roots. This requirement stems from the need to be able to pivot the blade or airfoil about its vertical axis to adapt its angle of attack for flight evaluations (variable-pitch blades or airfoils). This requirement (together with the fact that the blade or airfoil must be integrated as low as possible on the disk) makes it possible to significantly reduce the volume of the root.

[0006] To this end, the roots of the new generation blades or airfoils have an axisymmetric or substantially axisymmetric shape and reduced dimensions, unlike the roots of the prior art, such as described in document US 2013 / 0017093, which extend over the entire length of the lower part of the blade or airfoil.

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

[0008] Furthermore, the mechanical loads to which the new generation root is subjected impose additional stresses. Specifically, in addition to the mechanical tensile and bending loads typically encountered (caused by centrifugal forces and impacts with objects, respectively), the new generation root may also be bonded to the rotor disk using a metal shell, which creates additional mechanical circumferential compressive loads. Summary of the Invention

[0009] It would therefore be desirable to provide a solution for producing aircraft blades or propeller airfoils made of composite materials having a compact root and being able to resist different mechanical loads.

[0010] To this end, the invention provides a method for manufacturing a turboprop blade or propeller airfoil made of composite material, the blade or propeller airfoil comprising a fiber reinforcement densified by a matrix, the method comprising:

[0011] - producing a fiber blank made in one piece by three-dimensional weaving, the fiber blank having a flat shape extending in a longitudinal direction and a transverse direction corresponding respectively to the span direction and the chord direction of the blade or propeller airfoil to be manufactured, the fiber blank comprising a root portion and an aerodynamic profile portion extending from the root portion in the longitudinal direction and in the transverse direction between the leading edge portion and the trailing edge portion;

[0012] - shaping the fiber blank to obtain a fiber preform as a single piece, the fiber preform having an aerodynamic profile preform formed by the aerodynamic profile portion and a root preform formed by the root portion; and

[0013] - densification of the preform by means of a matrix to obtain a blade or propeller airfoil made of composite material having a fiber reinforcement consisting of a fiber preform and densified by means of a matrix and formed as a single piece with an integrated root;

[0014] Characteristically, the root portion of the fiber blank includes a non-interconnected structure extending along a plane parallel to the surface of the fiber blank throughout the root portion, the non-interconnected structure dividing the root portion into two braided portions, and forming the fiber blank includes winding each braided portion around an insert to form a root preform.

[0015] The method of the invention thus makes it possible to produce propeller aerofoil or blades having a composite root which is both compact and perfectly adapted to resist the different mechanical loads described above. In particular, the fiber-reinforced portion of the root is made using 3D weaving and has a wound shape which is connected to the fiber-reinforced portion of the aerodynamic profile at the center. Thus, a composite root can be obtained which is more compact than the roots of the prior art which generally extend over the entire width of the lower part of the aerodynamic profile. In this composite root, there are yarns (e.g. warp yarns) oriented in the spanwise direction of the aerofoil or blade, which, when combined with the 3D weaving, gives the aerofoil or blade good mechanical tensile and bending properties. Furthermore, in the composite root, there are yarns (e.g. weft yarns) oriented in the chordwise direction of the aerofoil or blade, which gives the aerofoil or blade good mechanical resistance under circumferential compression.

[0016] Furthermore, the winding of the braided portion around the insert makes it possible to obtain a root having an axisymmetric or quasi-axisymmetric shape, which can be compatible with integration into a propeller rotation or pitch system.

[0017] By producing a fiber reinforcement in which the root portion and the aerodynamic profile portion are formed integrally, ie woven into one piece, very good mechanical resistance of the entire component, in particular of the connection between the root portion and the aerodynamic profile, is ensured.

[0018] According to one aspect of the method of the present invention, each braided portion includes a first portion extending from the aerodynamically contoured portion in a longitudinal direction and a second portion extending from the first portion in the longitudinal direction, wherein the second portion has a width in a transverse direction greater than a width of the first portion. The width of the second portion of each braided portion in the transverse direction is equal to at least half of the circumference of the portion of the insert around which the second portion of each braided portion is wrapped.

[0019] According to another aspect of the method of the present invention, the insert is composed of a fiber material selected from one of the following fiber materials: a three-dimensional braid, a unidirectional laminate, and a fiber mat; or composed of a metal material.

[0020] The present invention also relates to a turboprop blade or propeller airfoil made of composite material, comprising a fiber reinforcement densified by a matrix, the blade or propeller airfoil comprising a root and an aerodynamic profile in the longitudinal direction, the fiber reinforcement comprising a fiber preform in the form of a three-dimensional woven body, the fiber preform having a root preform portion located in the root and an aerodynamic profile portion located in the aerodynamic profile, the root preform portion and the aerodynamic profile preform portion being connected to each other by three-dimensional weaving, characterised in that the root preform portion comprises two woven skin layers wound around an insert.

[0021] According to one aspect of the blade or propeller airfoil of the invention, each skin comprises a first portion extending in the longitudinal direction from the aerodynamically profiled preform portion and a second portion extending in the longitudinal direction from the first portion, the second portion of each skin being wound around at least half of the circumference of the portion of the insert around which the second portion of each braided portion is wound.

[0022] According to another aspect of the blade or propeller airfoil of the invention, the insert consists of a fiber material selected from the group consisting of: a three-dimensional braid, a unidirectional laminate and a fiber mat; or consists of a metallic material.

[0023] The invention also comprises an aerospace engine comprising a plurality of blades or propeller airfoils according to the invention, and an aircraft comprising at least one such engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram showing 3D weaving of a fiber blank for manufacturing a blade;

[0025] Figure 2 is a cross-sectional view of the yarn layer assembly on an enlarged scale, showing Figure 1 two non-interconnected structures formed along section II-II in the root portion of the blank;

[0026] Figure 3 It shows Figure 1 A perspective view of the formation of a root preform portion in a fiber blank;

[0027] Figure 4 FIG. 1 is a diagram showing an injection tool and an injection tool according to an embodiment of the present invention. Figure 3 An exploded schematic perspective view of the placement of a fiber preform therein;

[0028] Figure 5 It shows Figure 4 A three-dimensional schematic diagram of a closed injection tool;

[0029] Figure 6 It is a three-dimensional schematic diagram of a blade made of composite material obtained according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The present invention is generally applicable to different types of blades or propeller airfoils used in aircraft engines. The present invention has advantageous, but not exclusive, application in large-sized blades or propeller airfoils for incorporation into pivot or pitch control systems. Such blades or propeller airfoils are generally provided with a root having both a small volume (compact shape) and good resistance to tensile, bending and circumferential compression forces. The blade according to the invention can in particular be formed as a blade for a ducted impeller (such as a fan blade) or as a blade for an unducted impeller (as in an "open rotor" aircraft engine).

[0031] In the remainder of the description, exemplary embodiments are described with respect to blades for turboprop engines. However, these exemplary embodiments are also applicable to propeller airfoils for aircraft.

[0032] Figure 1 A fiber blank 100 for forming a fiber preform of a blade to be produced is shown very schematically.

[0033] like Figure 1 As shown schematically, the fiber structure blank 100 is obtained by three-dimensional (3D) weaving in a known manner using a jacquard loom on which a bundle of warp yarns 101 or strands is arranged, the bundle of warp yarns 101 or strands being made up of a plurality of layers, each layer having several hundred yarns, 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 a longitudinal direction D corresponding to the span direction of the blade to be manufactured, between a lower part 100c and an upper part 100d.L The blade extends upward, between the leading edge 100a and the trailing edge 100b in a transverse direction D corresponding to the chord direction of the blade to be manufactured. T The blank extends upward, and comprises an aerodynamic profile portion 111 and a root portion 112. The aerodynamic profile portion 111 defines two surfaces 111e and 111f for forming the suction side and the pressure side of the blade respectively. The root portion 112 is used to subsequently form the blade root and extends along the longitudinal direction D L Extending to the outside of the aerodynamic profile blank 111, along the transverse direction D T Recessed from the front edge 100a and the rear edge 100b.

[0034] In the example shown, the 3D weaving uses an "interlock" weaving. The term "interlock" weaving should be understood here to mean a weaving in which each layer of weft yarns binds together several layers of warp yarns and all yarns in the same weft yarn column have the same movement in the weaving plane.

[0035] Other known types of three-dimensional weaving can be used, such as the one described in particular in document WO 2006 / 136755. This document describes, in particular, the production of a workpiece, such as a blade, having a first weave in the core and a second weave in the skin, by weaving a fiber-reinforced structure into a single piece, thereby making it possible to impart both desired mechanical and aerodynamic properties to such a workpiece.

[0036] The fiber blank according to the invention can in particular be woven from carbon or ceramic fiber yarns, such as silicon carbide.

[0037] As fiber blanks of varying thickness and width are woven, a certain number of warp yarns are not woven, which makes it possible to define a desired continuously variable profile and thickness of the blank 100. An example of variable 3D weaving is described in document US 2006 / 257260, in which the thickness of the blank can be varied between a first edge forming a leading edge and a second edge of lesser thickness forming a trailing edge.

[0038] According to the present invention, during the weaving process, a non-interconnected structure 106 is formed between two consecutive warp yarn layers in the root portion 112 of the fiber blank 100. The non-interconnected structure 106 extends along a plane parallel to the surface of the fiber blank and extends over the entire surface of the root portion 112, dividing it into two woven portions 113 and 114.

[0039] Figure 2 The 3D weaving pattern of the blank 100 using interlock weaving is schematically shown. Figure 2is an enlarged partial view of a warp yarn cross section in the root portion 112 of the blank 100, including the non-interconnected structure 106 ( Figure 1 II-II section in FIG. 1 ). In this example, the blank 100 includes a substantially longitudinal direction D L The eight layers of warp yarns 101 are extended, and the non-interconnected structure 106 divides the eight layers of warp yarns into two groups, each group having four layers of warp yarns. More specifically, Figure 2 , the woven portion 113 includes four layers of warp yarns 101 interconnected by four weft yarns T1 to T4, and the woven portion 114 includes four layers of warp yarns interconnected by four weft yarns T5 to T8.

[0040] In other words, the fact that weft yarns T1 to T4 do not extend into the warp yarn layers of woven portion 114 and weft yarns T5 to T8 do not extend into the warp yarn layers of woven portion 113 ensures the non-interconnected structure 106 separating woven portions 113 and 114 .

[0041] In the example described here, the root portion 112 has an inverted T-shape. More precisely, the woven portions 113 and 114 each include a plurality of woven portions extending from the aerodynamic profile portion 111 along the longitudinal direction D L The first portions 113a and 114a extend in the longitudinal direction, and the second portions 113b and 114b extend from the first portions 113a and 114a in the longitudinal direction, respectively. The second portions 113b and 114b extend in the transverse direction D. T Width l 113b 、l 114b are respectively greater than the width l of the first portion 113a, 114a 113a 、l 114a The second portions 113b, 114b of the woven portions 113, 114 are each woven along the transverse direction D T Width l 113b 、l 114b Equal to at least half the circumference of the portion of the insert around which the second portion is wrapped.

[0042] Once the weaving is complete, the unwoven yarns surrounding the fiber blank 100 are cut to extract the blank, and then the root portion of the blank is formed. In the example described here, the root portion 112 is formed by winding the woven portions 113 and 114 around the insert 130, as shown in FIG. Figure 3 The insert, or at least the portion of the insert around which the braided portion is wound, preferably has an axisymmetric or substantially axisymmetric shape in order to form a compact root that is easily integrated into a propeller rotation or pitch system.

[0043] Depending on the width of the second portions 113b and 114b of the braided portions 113 and 114, each of these braided portions can be wound around half the circumference of the insert, around the entire circumference of the insert, or around a multiple of the circumference of the insert. In the example described here, the second portions 113b, 114b of the braided portions 113, 114, respectively, are each wound along the transverse direction D T Width l 113b 、l 114 Equal to half the circumference of the portion of the insert around which the second portion is wrapped.

[0044] This results in a fiber preform 200 which is formed along the longitudinal direction D L The aerodynamic profile preform portion 211 and the root preform portion 212 having a bulb shape, such as Figure 4 The root preform portion 212 comprises two skins 2121 and 2122 wound around the insert 130, wherein the first skin portions 2121a and 2122a form a half turn around the insert and the second skin portions 2121b and 2122b form a full turn around the insert. The aerodynamic profile preform portion 211 is formed between the leading edge portion 211a and the trailing edge portion 211b along the transverse direction D T extend.

[0045] Then carry out the densification of fiber preform.To the densification of the fiber preform for forming the fiber reinforcement to be manufactured workpiece, comprise filling the space of this preform with the material that constitutes matrix in all or part of the volume of preform.This densification is carried out in a manner known per se according to liquid technology (CVL).Liquid technology comprises impregnating preform with the liquid mixture containing matrix material precursor.This precursor is in polymer form usually, such as high performance epoxy resin, and it is diluted in solvent when applicable.Preform is placed in mould, and this mould can be sealed with the housing with moulding final part shape.Next, close this mould again and liquid matrix precursor (such as resin) is injected in whole housing, with the whole fiber part of prepreg preform.

[0046] The conversion of the matrix precursor (ie its polymerization) is accomplished by thermal treatment (generally by heating the mold) and, after removal of any solvent and crosslinking of the polymer, the preform remains in the mold in the same shape as the workpiece to be produced.

[0047] If a carbon or ceramic matrix is ​​formed, the heat treatment includes pyrolyzing the precursor 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 resin of the polycarbosilane (PCS) or polytitanium carbosilane (PTCS) or polysilazane (PSZ) type, while the carbon liquid precursor can be a resin with a relatively high coke ratio, such as a phenolic resin. Several consecutive cycles from impregnation to heat treatment can be performed to achieve the desired degree of densification.

[0048] According to one aspect of the present invention, particularly when an organic matrix is ​​formed, densification of the fiber preform can be accomplished by the well-known RTM (resin transfer molding) process. According to the RTM process, the fiber preform is placed in a mold having the shape of the workpiece to be produced. A thermosetting resin is injected into the interior space of the mold containing the fiber preform. To control and optimize the impregnation of the preform with the resin, a pressure gradient is typically established in this interior space between the resin injection point and the discharge orifice.

[0049] like Figure 4 As shown, the injection of the liquid matrix precursor mixture into the fiber structure and its conversion into the matrix takes place in an injection tool 300, which comprises a first shell 310 and a second shell 320. The first shell 310 comprises a first cavity 311 at its center, which partially corresponds to the shape and size of the blade to be produced, and the second shell 320 comprises a second cavity 321 at its center, which partially corresponds to the shape and size of the blade to be produced.

[0050] Once the tool 300 is Figure 5 As shown, the first shell 310 and the second shell 320, each with a first cavity 311 and a second cavity 321, together define an interior space 301 having the shape of the blade to be produced, and within which the fiber preform 200 is placed. With the tool 300 closed, the fiber preform 200 can be compacted to achieve a desired fiber content in the preform. In this case, compaction pressure is applied to the shells 310 and 320, for example, by a press. Alternatively, compaction of the fiber preform can be accomplished in a separate tool before the preform is introduced into the injection mold.

[0051] The tool 300 also includes a device for performing the injection of the liquid matrix precursor and the conversion of the precursor into the matrix. More specifically, in the example described here, the first shell 310 of the tool 300 includes an injection port 313 for allowing the liquid matrix precursor mixture to be injected into the fiber preform, and the second shell includes an exhaust port 323 for interacting with the pumping system to evacuate the tool and suck in air during the injection process. The injection tool 300 also includes a lower part 340 and an upper part 350, between which the first shell 310 and the second shell 320 are placed, and the lower part 340 and the upper part 350 are equipped with a heating device ( Figure 5 not shown).

[0052] Once the tool 300 is closed, the blade is molded by impregnating the preform 200 with a thermosetting resin that polymerizes by heat treatment. For this purpose, the well-known injection or transfer molding process, so-called RTM (resin transfer molding), is used. According to the RTM process, 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 a discharge pipe ( Figure 5 (not shown in the figure). This configuration allows a pressure gradient to be established between the lower portion of the preform 200, into which the resin is injected, and the upper portion of the preform located near port 323. In this way, the resin 360 injected substantially flush with the lower portion of the preform will gradually impregnate the entire preform by circulating all the way to the discharge port 323, with the excess being discharged through the discharge port 323. Of course, the first shell 310 and the second shell 320 of the tool 300 may include several injection ports and several discharge ports, respectively.

[0053] For example, the resin used can be an epoxy resin with a temperature rating of 180°C (the maximum temperature it can withstand without loss of properties). Resins suitable for RTM processes are well known. They preferably have a low viscosity to facilitate their infusion into the fibers. The choice of temperature rating and / or chemical properties of the resin depends on the thermomechanical stresses to which the part is subjected. Once the resin has been infused throughout the reinforcement, it is polymerized by heat treatment according to the RTM process.

[0054] After injection and polymerization, the blade is demolded. Finally, the blade is trimmed to remove excess resin and chamfered. Since the molded part meets the required dimensions, no further machining is required.

[0055] The densification method described above is primarily used to produce blades or propeller airfoils made of organic matrix composite (OMC), carbon matrix (C / C) and ceramic matrix composite (CMC) materials from the fiber preforms of the invention.

[0056] like Figure 6 As shown, a blade 10 is obtained, formed from a fiber reinforcement densified by a matrix. The blade includes, in its lower portion, a root 12 formed from a root preform portion 212 of a fiber preform 200, and an airfoil 11 formed from an airfoil preform portion 211 of the fiber preform 200. Blade 10 includes a leading edge 11a and a trailing edge 11b, corresponding to the leading edge portion 211a and the trailing edge portion 211b of the fiber preform 200, respectively. Root 12 is bulbous in shape, with root preform portion 212 comprising two skins 2121 and 2122 wound around an insert 130. The first skin portions 2121a and 2122a form a half-turn around the insert, while the second skin portions 2121b and 2122b form a full turn around the insert. Consequently, blade 10 includes a root 12 with an axisymmetric, compact shape suitable for integration into a propeller rotation or pitch control system.

Claims

1. A method for manufacturing a turboprop blade or propeller airfoil (10) made of composite material, the blade or propeller airfoil comprising a fiber reinforcement densified by a matrix, the method comprising: - producing a single-piece fiber blank (100) by three-dimensional weaving, said fiber blank having longitudinal directions (D) corresponding respectively to the spanwise direction and the chordwise direction of the blade or propeller airfoil to be manufactured L ) and transverse direction (D T ), the fiber blank comprising a root portion (112) and an aerodynamic profile portion (111), the aerodynamic profile portion (111) extending from the root portion along the longitudinal direction (D L ) extends and extends between the leading edge portion (100a) and the trailing edge portion (100b) along the transverse direction (D T )extend; - shaping the fiber blank (100) to obtain a fiber preform (200) as a single piece, the fiber preform (200) having an aerodynamic profile preform (211) formed by the aerodynamic profile portion and a root preform (212) formed by the root portion; as well as - densifying the preform (200) by means of a matrix to obtain a blade or propeller airfoil (10) made of composite material, having a fiber reinforcement comprising the fiber preform and densified by means of the matrix and formed in a single piece with an integrated root (12); Characterized in that the root portion (112) of the fiber blank (100) includes a non-interconnected structure (106) extending along a plane parallel to the surface of the fiber blank throughout the root portion, the non-interconnected structure dividing the root portion into two woven portions (113, 114), and forming the fiber blank includes winding each woven portion around an insert (130) to form a root preform portion (212).

2. The method according to claim 1, wherein Each woven portion (113, 114) comprises a woven portion extending from the aerodynamic profile portion (111) along the longitudinal direction (D L ) and a first portion (113a, 114a) extending from the first portion (113a, 113b) along the longitudinal direction and a second portion (113b, 114b) extending from the first portion (113a, 113b) along the transverse direction (D T ) width (I 113b , I 114b ) is greater than the width (I 113a , I 114a ).

3. The method according to claim 2, wherein: The second portion (113b, 114b) of each woven portion (113, 114) is woven along the transverse direction (D T ) width (l 113b , l 114b ) is equal to at least half of the circumference of the portion of the insert (130) around which the second portion of each braided portion is wound.

4. The method according to any one of claims 1 to 3, wherein The insert (130) is made of a fiber material selected from one of the following fiber materials: a three-dimensional braid, a unidirectional laminate, and a fiber mat; or is made of a metal material.

5. A turboprop blade or propeller airfoil (10) made of composite material, comprising a fiber reinforcement densified by a matrix, the blade or propeller airfoil comprising a root (12) and an aerodynamic profile (11) along a longitudinal direction (DL), the fiber reinforcement comprising a fiber preform (200) in the form of a three-dimensional braid, the fiber preform (200) having a root preform portion (212) located in the root (12) and an aerodynamic profile portion (211) located in the aerodynamic profile (11), the root preform portion (212) and the aerodynamic profile preform portion (211) being connected to each other by performing three-dimensional braiding, characterized in that The root preform portion (212) includes a non-interconnected structure that divides the root preform portion into two braided skins (2121, 2122) that are wound around an insert (130).

6. A blade or propeller airfoil according to claim 5, wherein: Each skin layer (2121, 2122) comprises a plurality of layers extending from said aerodynamically contoured preform portion (211) along a longitudinal direction (D L ) and a first portion (2121a, 2122a) extending from the first portion (2121a, 2122a) along the longitudinal direction, the second portion of each surface layer being wrapped around at least half of the circumference of the portion of the insert (130) around which the second portion of each woven portion is wrapped.

7. A blade or propeller airfoil according to claim 5 or 6, wherein: The insert (130) is made of a fiber material selected from the group consisting of: a three-dimensional braid, a unidirectional laminate, and a fiber mat; or a metal material.

8. An aircraft engine comprising a plurality of blades or propeller airfoils (10) according to any one of claims 5 to 7.

9. An aircraft comprising at least one engine according to claim 8.

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