Method of manufacturing a blade comprising serrated elements from a composite material

Abstract

The invention relates to a method for manufacturing a blade (7) made of composite material for a turbine engine, said method comprising the following steps: (a) weaving fibers to produce a fibrous preform intended to form a part of a blade of said blade; (b) shaping and hardening said fibrous preform in a pre-forming tool; (c) inserting said fibrous preform into a mold; (d) densifying said fibrous preform with a resin to form said blade, wherein: - before and / or after step (c), said method further comprises a step (i) of inserting fibrous layers into said mold so that at least a part of the edges of said fibrous preform are covered, these fibrous layers having corrugated or toothed edges; - during step (d), said fibrous layers are also densified by said resin to form serrated elements.

Description

Technical Field

[0001] This invention relates to the field of turbine engines, particularly to turbine engines for aircraft, and especially to propellers comprising blades for such turbine engines. More specifically, this invention relates to a method for manufacturing blades made of composite materials for such turbine engines, and even more specifically to improving noise reduction of these blades during operation. Background Technology

[0002] The prior art includes, in particular, document FR-A1-3111660.

[0003] Aircraft turbine engines typically include a gas generator that drives at least one propeller. The gas generator includes at least one compressor, a combustion chamber, and at least one turbine. The rotor of the gas generator, or one of its rotors, is connected to the rotor of the propeller to drive its rotation.

[0004] The propeller can be ducted. This is the case, for example, with the fan in a turbojet or turbofan type turbine engine.

[0005] Propellers can be ductless. For example, turboprops or "open rotor" type architectures are such examples.

[0006] A propeller comprises an annular array of blades rotating about the longitudinal axis of a turbine engine. Each blade includes a pressure side and a suction side connected by a leading edge and a trailing edge. Turbine engine blades, such as fan blades or stator blades of a turbine engine, are known to be manufactured from composite materials to reduce mass while maintaining good mechanical properties. For example, composite blades are manufactured by resin injection, such as by injecting liquid resin (“Resin Transfer Molding (RTM)”) into a fiber preform.

[0007] Seeking to minimize pollution emissions associated with air transport involves improving all the efficiencies of propulsion systems (or, in other words, turbine engines), and more specifically, improving propulsion efficiency, which characterizes the efficiency of converting the energy transferred to the air passing through the engine into useful thrust.

[0008] The components that affect propulsive efficiency in the first order are those related to the low-pressure components of the turbine engine, such as the low-pressure turbine, low-pressure transmission system, propeller, and secondary flow guiding the propeller's flow. These low-pressure components immediately contribute to thrust generation. A known guiding principle for improving propulsive efficiency is to reduce the propeller's compression ratio, thereby reducing the flow velocity at the turbine engine exit and the associated kinetic energy loss.

[0009] One of the main consequences of the reduced flow velocity at the turbine engine outlet is the need to manage the larger mass of airflow in the low-pressure components (especially in the secondary flow) to ensure a given thrust level, which is fixed by the aircraft's characteristics. This, in turn, leads to an increased dilution rate in the turbine engine. The dilution ratio, or bypass ratio (BPR), is defined as the ratio between the mass flow through the secondary flow (or so-called cold flow) around the gas generator and the mass flow through the main flow (or so-called hot flow) in the gas generator, specifically supplied to the combustion chamber. This increase in the secondary flow has the direct effect of requiring an increase in propeller diameter, and thus, in the case of a ducted propeller, an increase in the external dimensions of the retaining casing surrounding it and the nacelle that constitutes the aerodynamic envelope of that retaining casing. To achieve a high dilution rate, the retaining casing is removed to switch to a ductless propeller configuration, as the retaining casing becomes too large, too heavy, and generates significant trap drag.

[0010] In the case of ducted propellers, the nacelle surrounding the propeller includes internal acoustic treatment to reduce external noise emissions from the turbine engine.

[0011] In the case of ductless propellers, alternative solutions must be found to reduce propulsion noise. To address noise emissions, noise reduction techniques already known in fans and particularly inspired by the wings of nighttime raptors involve installing serrated elements (or, in other words, sawtooths) on the trailing edge of blades (such as the so-called rotor blades of a fan) or the leading edge of blades (such as the so-called stator blades of a turbine engine). Sawtooths are aeroacoustic elements. They are characterized by a tooth-like geometry, varying in number and size, and changing along the trailing or leading edge. The sawtooths cause the chord of the blade to vary with radial height, resulting in different thicknesses and very thin trailing or leading edges.

[0012] The principle of reducing noise generated by turbine blades is based on the spatial movement of noise sources distributed along the leading or trailing edge by means of sawtooth (or in other words, corrugations or teeth). These sawtooth teeth may be the same or different. To apply this principle, the dimensions of the sawtooth (height, length, thickness, etc.) must be adapted to the incident aerodynamic field (e.g., airflow through the turbine blades with more or less turbulence), which varies depending on the engine speed of the turbine engine.

[0013] In addition, the sawtooth element must be easy to repair (because passengers can see it) and be able to resist high-cycle fatigue (HCF) type damage, which can cause cracks in the sawtooth element (and thus in the impeller) during operation.

[0014] Furthermore, when manufacturing impellers that include such serrated elements made of composite materials, many other constraints need to be considered, such as: - Serrated elements have complex geometries, particularly the teeth exhibiting variations in dimensions (such as thickness, length, shape, tooth spacing, and the curvature of the forming angle β2), which can alter and create misalignment with composite materials (especially woven fibers) during RTM injection molding. The positioning of the serrated element on the leading or trailing edge can be complex, especially for the complex geometry (size and shape) of the pneumatic impeller. - The teeth of the sawtooth element have thin walls (minimum approximately 2.5mm), which may be damaged during processing, and - Producing sawtooth elements with reasonable quality so as not to depress the propeller and with good mechanical properties to withstand impacts, especially from external objects such as birds, hail, or lightning. In addition to the aforementioned technical constraints, manufacturing blades that include sawtooth elements from composite materials can be lengthy, complex, and expensive.

[0015] In this context, it is of interest to propose a solution that addresses at least one of the aforementioned drawbacks, particularly by optimizing and robustly integrating the serrated element into the impeller made of composite materials. Summary of the Invention

[0016] This invention provides a simple, effective, and economical solution to the aforementioned shortcomings of the prior art.

[0017] Therefore, the present invention relates to a method for manufacturing composite material blades for turbine engines, particularly for turbine engines used in aircraft. The impeller includes a blade, the blade having a leading edge, a trailing edge, a pressure side and a suction side extending between the leading edge and the trailing edge, and the blade further including at least one serrated element on the leading edge and / or the trailing edge. The method includes the following steps: (a) Producing a fiber preform by weaving fibers, the fiber preform being designed to form a portion of the blade. (b) Forming and hardening the fiber preform in a preforming tool, (c) Inserting the fiber preform into the mold, and (d) Densify the fiber preform with resin to form the blade.

[0018] According to the present invention: - Before and / or after step (c), the method further includes step (i) of inserting fiber layers into the mold such that at least a portion of the edge of the fiber preform is covered, these fiber layers having corrugated or serrated edges. - During step (d), the fiber layer is also densified by the resin to form the at least one sawtooth element.

[0019] The manufacturing method according to the invention makes it easier and more robust to integrate serrated elements into the blade. To this end, the invention proposes forming the serrated elements and blade integrally (or in other words, integrally and in one piece) from a composite material. Therefore, prior to the densification step, a fiber layer intended to form the serrated elements is applied directly to at least a portion of the edge of the fiber preform. This integral connection is easy to achieve (especially in an automated manner), robust, and resistant to damage during operation. In particular, the direct integration of the serrated elements into the fiber preform allows for the formation of a more robust blade, particularly regarding the technical constraints mentioned in the background section, and good cohesion of the fibers throughout the fiber preform. This significantly improves the mechanical strength of the blade during operation, for example, in a turbine engine.

[0020] Furthermore, the method according to the present invention has the following advantages: - Reduce or maintain a reasonable mass of the blade by manufacturing sawtooth elements and blades from a single composite material; - Facilitates the realization of complex geometries for sawtooth elements, especially by producing teeth and angle β2 directly in the mold during the densification step; - Maintain the geometry of a subset of the added fiber layers on the edges of the fiber preform to limit stress transfer from the fiber preform to the hollow portion of the sawtooth element; - Facilitates the repair and / or replacement of the fiber layer of the sawtooth element; - To minimize fiber and / or resin loss, for example when cutting fiber preforms, especially compared to direct processing solutions for serrated elements on the leading or trailing edge; -Automating all or at least some steps in the method; and - Significantly reduces the cost and time required to manufacture wheel blades.

[0021] Therefore, the present invention offers the following advantages: it provides very high reliability based on an easily manufactured design, and suffers from low losses in cost, quality, and overall size. In this way, the impeller obtained according to the method of the present invention helps to limit environmental impact, particularly by reducing mass.

[0022] The term "serrated element" refers to a component that includes teeth protruding from at least a portion of the component. These teeth may be U-shaped and / or V-shaped in axial cross-section. These teeth may be more or less numerous, more or less large, and extend along the serrated element. A serrated element may also be referred to as a toothed or corrugated element.

[0023] The manufacturing method according to the present invention may include one or more of the following features, individually or in combination with each other: -in: - Prior to step (c), the first fiber layer is positioned directly in the mold, and - After step (c), the second fiber layer is positioned directly on the edge of the fiber preform or even on top of the first fiber layer. The edge of the preform is inserted between the first fiber layer and the second fiber layer; - A third fiber layer is inserted between the first fiber layer and the second fiber layer, and is located next to the edge without covering the edge; - Before or during step (i), the method further includes step (ii) of adding an adhesive layer between the fiber layer and the edge of the fiber preform, the adhesive layer being, for example, based on epoxy resin; -The method further includes step (iii) of cutting the fiber preform to form a recess in the fiber preform prior to step (b); - The mold includes at least one cavity, a portion of which has a shape complementary to the corrugated or serrated edge of the fiber layer; - Prior to step (d), the method includes at least one step of compacting the fiber preform and the fiber layer; - The fiber layer is made by weaving fibers or stacking multiple layers of fibers; - Prior to step (d), the fiber preform and the fiber layer are pre-impregnated with resin; - The resin is thermosetting or thermoplastic, for example, epoxy-based; --Step (d) is performed by heating to a temperature of 150°C to 200°C, preferably about 180°C; --The fiber preform is formed from unidirectional (1D), two-dimensional (2D), or three-dimensional (3D) woven fibers; --The fiber preform includes carbon fiber, glass fiber, aramid fiber, ceramic fiber (e.g., silicon carbide), or a mixture of at least two of these fibers; --The fiber layer comprises carbon fiber, glass fiber, aramid fiber, ceramic fiber (e.g., silicon carbide), or a mixture of at least two of these fibers; - The fiber layer has an elongated shape along the edge of the fiber preform; - The fiber layer extends over at least 70% of the length of the edge of the fiber preform; --The fiber layer extends over up to 90% of the length of the edge of the fiber preform; - At least some of the fiber layers have a first surface and a second surface, the first surface directly covering the edge of the fiber preform and / or separated from the edge of the fiber preform by other fiber layers, the second surface directly covering or being covered by the other fiber layers, and the first surface having a larger extent than the second surface.

[0024] --At least some of the fiber layers are either covered by fiber layers or inserted between two fiber layers; --At least some of the fiber layers do not cover the edges of the fiber preform; --The fiber layer is, for example, pre-impregnated with resin; --The fiber layers are dry (or in other words, non-pre-impregnated, meaning that these layers are not pre-impregnated with resin). --The fiber preform is dry (or in other words, not pre-impregnated); --The fiber layers introduced into the mold include a first fiber layer, a second fiber layer, and possibly a third fiber layer; --The corrugated or toothed edge is intended to form the serrated element; --The edges of the fiber layer are corrugated and / or serrated; --The edges of the fiber layer include corrugations or teeth (or in other words, protrusions); --The corrugations or teeth may have the same or different shapes from each other; --The corrugations or teeth each have a generally polygonal shape (e.g., triangles, rectangles, etc.). --The ripples exhibit a contour that follows a periodic pattern, such as a sine wave; --The ripples are in the form of a periodic signal with one or more harmonics; --The corrugations or teeth are more or less regularly distributed along the edges of the fiber preform.

[0025] The invention also relates to a composite material blade for a turbine engine, particularly for an aircraft turbine engine, obtained by a manufacturing method according to one of the features of the invention. The invention further relates to an aircraft turbine engine comprising at least one composite material blade according to the invention.

[0026] The turbine engine can be an aircraft turbojet engine, a turboprop engine, or a turboshaft engine. Attached Figure Description

[0027] The invention will be better understood from the following description by way of non-limiting example and with reference to the accompanying drawings, in which other details, features and advantages of the invention will become clearer: Figure 1 This is a schematic half-view of an axial section of an aircraft turbine engine having a ducted propeller and ducted stator blades, each of which includes blades. Figure 2 It is a schematic perspective view of a turbine engine with a ductless propeller and ductless stator blades, each of which includes blades. Figure 3 It indicates that it comes from Figure 1 or Figure 2 A schematic outline of a first example of a turbine engine blade, the blade including serrated elements on the leading edge of the blade; Figure 4 It means Figure 1 or Figure 2 A schematic outline of a second example of a turbine engine blade, the blade including a serrated element on one trailing edge; Figure 5 It is used for manufacturing Figure 3 or Figure 4 A block diagram of the method for using impeller blades; Figure 6 It is intended to form Figure 4 A schematic perspective view of a fiber preform of a portion of the impeller; Figure 7a It is a perspective view of the mold that enables the densification of fiber preforms; Figure 7b yes Figure 7a A schematic enlarged perspective view of the mold in the image; Figure 8 This is a schematic partial axial cross-sectional view showing the fiber layer on the edge of a fiber preform according to an embodiment of the present invention; Figure 9 yes Figure 8 A schematic perspective view of the mold, including the deposition of fiber layers; Figure 10 yes Figure 9 A schematic perspective view of the mold, including the deposition of fiber preforms; Figure 11 yes Figure 10 A schematic perspective view of the mold, also including the deposition of other fiber layers; Figure 12 This is a partial axial cross-sectional view schematically illustrating an adhesive layer inserted between the fiber layer and the edge of the fiber preform according to another embodiment of the invention.

[0028] Elements that have the same function in different embodiments have the same reference numerals in the drawings. Detailed Implementation

[0029] By convention, in the following description, the terms "longitudinal" and "axial" define the orientation of a structural element (e.g., a turbine engine or blade) extending along a longitudinal axis. The terms "radial" or "vertical" refer to the orientation of a structural element extending along a direction perpendicular to the longitudinal axis. The terms "inner" and "outer," as well as "internal" and "external," are used with regard to positioning relative to the longitudinal axis. Thus, a structural element extending along the longitudinal axis includes an inner surface facing the longitudinal axis and an outer surface opposite to its inner surface.

[0030] This invention can be applied in a non-limiting manner to turbine engine 10, particularly to turbine engines of aircraft. Turbine engine 10 can be a turbojet engine, a turboprop engine, or a turboshaft engine.

[0031] The turbine engine 10 can extend around the longitudinal axis X.

[0032] The turbine engine 10 typically includes a gas generator that drives at least one propeller 1. The gas generator includes at least one compressor, a combustion chamber, and at least one turbine. The rotor of the gas generator, or one of its rotors, is connected to the rotor of the propeller to drive its rotation.

[0033] The propeller 1 can be ducted. This is the case, for example, with the fan in a turbojet or turbofan type turbine engine.

[0034] As an example, not a limitation, Figure 1 A turbine engine 10 is shown, which, from upstream to downstream in the airflow direction F along the longitudinal axis X, includes a ducted propeller 1 (also called a fan), at least one compressor (such as a low-pressure compressor 2 and / or a high-pressure compressor 4), a combustion chamber 5, at least one turbine 6 (such as a high-pressure turbine and / or a low-pressure turbine), and nozzles ( Figure 1 (Not shown in the image).

[0035] Propeller 1 can be a ductless type. Figure 2 For example, this is the case with turboprop engines.

[0036] As an example, not a limitation, Figure 2 This turbine engine 10 includes a ductless propeller 1.

[0037] Therefore, the turbine engine 10 may include an upstream propeller 1 (whether ducted or ductless) and a downstream stator blade 3.

[0038] The propeller 1 may include blades 7 (referred to as rotor blades) extending around an axis X. The blades 7 of the propeller 1 allow airflow to be drawn in. Figure 1 In the case of the turbine engine 10 shown, the airflow can be divided into a main flow and a secondary flow. The main flow passes through the main duct in the turbine engine 10, while the secondary flow is guided toward the secondary duct surrounding the main duct.

[0039] The stator blade 3 includes blades 7 (referred to as stator blades) extending around the axis X. The blades 7 of the stator blade 3 are used to rectify the flow at the upstream rotor outlet to provide maximum thrust at the outlet of the turbine engine 10.

[0040] In the following description, special reference will be made. Figure 3 and Figure 4 The invention is described in the context of its application in a non-limiting manner to the blade 7. This blade 7 can be moved on the propeller 1 or fixed to the stator blade 3.

[0041] The 7th blade can be extended as follows: -Elongation axis A (in) Figure 3 and Figure 4 (roughly vertical), which is basically perpendicular to or inclined to the axis X of the turbine engine 10. -Longitudinal axis B (in) Figure 3 and Figure 4 (roughly horizontal), which is roughly perpendicular to axis B, and - A transverse axis C that is essentially perpendicular to axes A and B.

[0042] The impeller 7 includes a blade 70 that can be connected to the root 76 of the impeller. The blade 70 includes a leading edge 73, a trailing edge 74, a pressure side 71 and a suction side 72 extending between the leading edge 73 and the trailing edge 74.

[0043] The blade 70 may have an aerodynamic profile to form the aerodynamic portion of the blade 7. For this purpose, the blade 70 may have a curved profile with variable thickness between the leading edge 73 and the trailing edge 74 of the blade 7.

[0044] exist Figure 3 and Figure 4 In the example, blade 70 can extend along axis A between a first end and a second end opposite to the first end.

[0045] The root 76 can be attached to the second end of the blade 70. It is intended to be fixed to, for example, a disk (not shown) that can rotate about axis X. The second end is free and is configured to form the top 75 (or tip) of the blade 7.

[0046] The blade 70 also includes at least one serrated element 8 on at least a portion of the leading edge 73 and / or at least a portion of the trailing edge 74. As described below, the serrated element reduces aerodynamic noise generated by the blade during operation.

[0047] Therefore, blade 70 may include the blade located at leading edge 73 ( Figure 3 ) or trailing edge 74 ( Figure 4 The serrated element 8 can be located at the leading edge 73 or two different serrated elements 8 located on the trailing edge 74, respectively. For example, when the blade 7 corresponds to the blade of the propeller 1 of a ductless turbine engine, the serrated element 8 can be located on the leading edge 73. When the blade 7 corresponds to the blade of the stator blade 3 of a ducted turbine engine, the serrated element 8 can be located on the trailing edge 74.

[0048] The serrated element 8 may include corrugations or teeth 82 (or in other words, protrusions). For example, the serrated element 8 may include five to twenty teeth 82. These teeth 82 may be aligned with each other, particularly along the leading edge 73 or the trailing edge 74. The teeth 82 may extend partially or completely along the leading edge 73 and / or the trailing edge 74. The teeth 82 may be identical or different from each other. The teeth 82 may be configured to reduce noise in the intermediate emission spectrum without significantly degrading other frequencies at other engine speeds.

[0049] The shape of the corrugations or teeth 82 can be the same or different.

[0050] The corrugations or teeth 82 can each have a roughly polygonal shape (such as triangles, rectangles, etc.).

[0051] Ripples can have a profile that follows a periodic law, such as a sine wave. For example, ripples can take the form of a periodic signal with one or more harmonics.

[0052] The ripples or teeth 82 may be more or less regularly distributed along the leading and / or trailing edges.

[0053] The sawtooth element 8 can cause the chord of the blade to vary according to the radial height (relative to axis A), having a variable thickness and a very thin leading edge 73 or trailing edge 74.

[0054] In addition, the impeller 7 may optionally include a metal reinforcement (not shown in the figure). The metal reinforcement may at least partially cover the leading edge 73 or the trailing edge 74. Advantageously, the metal reinforcement may extend from the leading edge 73 over a portion of the entire height (relative to axis A) and length (relative to axis B) of the leading edge 73 on the pressure side 71 and suction side 72.

[0055] Preferably, the metal reinforcement may have a U-shaped or V-shaped cross section relative to axis A to cover at least a portion of the leading edge 73 or the trailing edge 74.

[0056] Metal reinforcements protect the blades (especially the blade blades) from external impacts (gravel on the runway, hail, birds, etc.) and prevent blade erosion.

[0057] Metal reinforcements can be fixed by gluing or by spraying a film (such as a metal film).

[0058] The metallic material of the metal reinforcement is, for example, titanium or an alloy such as steel (e.g., stainless steel) or nickel-cobalt alloy (NiCo).

[0059] The blade 7 is made of composite material. The blade 7 may include a fiber preform 700, which may be embedded (or otherwise densified) in a resin (or a polymer matrix after resin densification).

[0060] The term "fiber preform" refers to an intermediate component used in the production of the final blade 7. The composite material can be, for example, an organic matrix composite (CMO) or a ceramic matrix composite (CMC).

[0061] Organic matrix composites (CMOs) and ceramic matrix composites (CMCs) are used to replace metal components in certain turbine engine parts, such as turbine blades. Furthermore, their use helps optimize aircraft performance, particularly by significantly reducing harmful emissions (CO, CO2, NOx, etc.) by improving turbine engine efficiency and reducing the overall weight of the turbine engine.

[0062] refer to Figures 5 to 12 This application will now describe a method for manufacturing the impeller 7 as described above.

[0063] According to the present invention, a method for manufacturing a wheel blade 7 made of composite material includes the following steps: (a) Producing fiber preforms 700 by weaving fibers, (b) Forming and hardening the fiber preform 700 in a preforming tool. (c) Insert the fiber preform 700 into the mold M, and (d) Densifying the fiber preform 700 with resin to form the blade 7.

[0064] One of the significant features of this invention is: - Before and / or after step (c), the method further includes step (i) of inserting fiber layers 80 into the mold M such that at least a portion of the edges 740 of the fiber preform 700 is covered, these fiber layers 80 having corrugated or serrated edges 800. - During step (d), the fiber layer 80 is also densified with resin to form the serrated element 8.

[0065] As previously described, the introduction of a fiber layer 80 on the edge 740 of the fiber preform enables, particularly during the densification step (d), the serrated element 8 to be integrally bonded and formed on the leading edge 73 or trailing edge 74 of the blade.

[0066] Figure 5 The steps in the manufacturing method of the present invention are summarized, wherein optional steps in the method are shown in dashed lines.

[0067] In step (a), the fiber preform 700 may be formed from two-dimensional or three-dimensional woven fibers.

[0068] The fiber preform 700 may include carbon fiber, glass fiber, aramid fiber, ceramic fiber (such as silicon carbide), or a mixture of at least two of these fibers.

[0069] The fiber preform 700 may be pre-impregnated with resin, particularly prior to the densification step (d). Alternatively, the fiber preform 700 may be described as “dry,” meaning it is not pre-impregnated with resin.

[0070] The fiber preform 700 is intended to form part of the blade 70. In particular, the fiber preform 700 may form the leading edge 73, trailing edge 74, pressure side 71, and suction side 72 of the blade 70.

[0071] The fiber preform 700 may include at least one edge 740. This edge 740 may be intended to form the leading edge 73 or trailing edge 74 of the blade 70. In other words, the edge 740 may extend into the leading edge 73 or trailing edge 74. The edge 740 may have an elongated shape along a plane substantially parallel to axis A. The edge 740 may be smooth and flat.

[0072] Step (a) may also include, for example, manually pre-cutting any loose fibers (such as warp fibers) on the fiber preform 700 obtained after weaving the fibers.

[0073] Advantageously, the method may further include step (iii) of cutting the fiber preform 700 prior to step (b) to form a recess 742 in the fiber preform 700. The recess 742 makes it particularly possible to form an edge that corresponds specifically to the edge 740 and has a smooth surface suitable for receiving the fiber layer 80.

[0074] Alternatively, the recessed surface 742 may not be smooth. In this configuration, the recessed surface 742 may have a surface, such as serrated, curved, or a mixture of these types of non-smooth surfaces.

[0075] The recess 742 (or in other words, the hollow portion) may be formed at the edge 740 of the fiber preform and / or toward the interior of the fiber preform 700 (i.e., on the pressure side and / or suction side of the fiber preform). Figure 6 A recess 742 at the edge 740 of the fiber preform 700 is shown in a non-limiting manner, intended to form a trailing edge 74. Alternatively, the recess 742 may be located on the edge of the fiber preform on the side of the leading edge 73.

[0076] The recess 742 may extend over at least 70% of the length of the edge 740 of the fiber preform. The length of the edge 740 may be measured substantially along axis A. In particular, the recess 742 may extend over at most 90% of the length of the edge 740 of the fiber preform.

[0077] The fiber preform 700 can be cut using at least one technique selected from: water jet, circular cutter, ultrasonic scalpel, and a pair of scissors. The ultrasonic scalpel can have a long and sharp cutting edge.

[0078] Step (b) enables the preforming of the woven fiber preform 700 obtained at the end of step (a) or (iii). This step (b) can be performed in a suitable preforming tool (not shown in the figure).

[0079] Step (b) may include a sub-step (b1) of applying water to, for example, the fiber preform obtained at the end of step (a) or step (iii). This makes it possible to wet the fiber preform 700. Thus, wetting the fiber preform with water makes it easier to handle.

[0080] Step (b) may include a sub-step (b2) of positioning the fiber preform 700 obtained in step (a) or (iii) in a preforming tool. For this purpose, the fiber preform 700 may include tracer fibers on its surface, which may be aligned with a laser projection of the theoretical tracer fiber positions of, for example, the warp and weft yarns formed by the preforming tool.

[0081] Step (b) may include a sub-step (b3) of drying by heating, for example by placing the enclosed preforming tool in an oven or autoclave. Drying may be carried out at temperatures above 100°C and may last for several hours. In particular, drying allows the water used for wetting to be dried and extracted from the fiber preform.

[0082] In step (c), the fiber preform 700, particularly obtained at the end of step (b) or (i), can be placed in a suitable mold M. The positioning of the fiber preform in the mold M can also be achieved using a fiber tracer on the surface of the fiber preform and its laser projection.

[0083] refer to Figure 7a and Figure 7b The mold M may include the geometry of the serrated element 8 such that the fiber preform 700 and the densified (or embedded) fiber layer 80 in the resin are as close as possible to the desired blade 7 geometry. Therefore, the mold M may include various corrugations of the blade 7 and the serrated element 8 (especially...). Figure 7b The angle β2 and / or radians shown are given.

[0084] Angle β2 can correspond to the angle between the plane tangent to the skeleton of the trailing edge (or in other words, the outer surface of the trailing edge) and the axis X. Advantageously, the mold M may include at least one cavity M7, a portion of which M... 80 It has a shape complementary to the corrugated or toothed edges 800 of the fiber layer 80. This makes it easier to form serrated elements 80 with their desired tooth geometry 82.

[0085] Specifically, the cavity M7 designed to form the impeller 7 may include a first cavity portion M 700 Second cavity part M 80 First cavity part M 700 It can have a shape complementary to the fiber preform 700 to facilitate the positioning of the fiber preform 700 in the mold and subsequent densification. Second cavity portion M 80 It can be configured to receive the fiber layer 80 (preferably with corrugated or toothed edges 800).

[0086] Advantageously, the edge 800 can be corrugated and / or serrated.

[0087] Therefore, edge 800 may include corrugations or teeth (or in other words, protrusions). These corrugations or teeth of edge 800 may have the same shape as each other or different shapes.

[0088] The 800-degree ripples or teeth on the edge can each have a roughly polygonal shape (such as triangles, rectangles, etc.).

[0089] The ripples at the 800-degree edge can present a contour that follows a periodic law, such as a sine wave.

[0090] The ripples at edge 800 can take the form of a periodic signal with one or more harmonics.

[0091] The corrugations or teeth can be more or less regularly distributed along the edge of the fiber preform.

[0092] Step (i) of introducing the fiber layer 80 into the mold M can be performed before and / or after step (c).

[0093] The fiber layer 80 can be made by weaving fibers or stacking multiple layers of fibers.

[0094] The fiber layer 80 may include carbon fiber, glass fiber, aramid fiber, ceramic fiber (such as silicon carbide), or a mixture of at least two of these fibers.

[0095] The weave type (e.g., two-dimensional or three-dimensional), fiber orientation (e.g., 0° and / or 45°), and / or fiber properties (e.g., carbon fiber, aramid fiber, etc.) of the fiber layer 80 can vary according to the desired stiffness.

[0096] The fiber layers 80 may be pre-impregnated with resin, particularly prior to the densification step (d). Alternatively, the fiber layers 80 may be described as “dry,” meaning they are not pre-impregnated with resin.

[0097] The fiber layer 80 can have an elongated shape, especially along the edge 740 of the fiber preform.

[0098] The fiber layer 80 may extend over at least 70% of the length of the edge 740 of the fiber preform (relative to axis A). In particular, the fiber layer 80 may extend over up to 90% of the length of the edge 740 of the fiber preform.

[0099] Advantageously, at least some of the fiber layers 80 may be covered by fiber layers 80 alone or inserted between two fiber layers 80.

[0100] At least some of the fiber layers 80 may not cover the edge 740 of the fiber preform 700.

[0101] At least some of the fiber layers 80 have a first surface 812 and a second surface 814, the first surface 812 having a larger extent than the second surface 814. The first surface 812 directly covers the edge 740 of the fiber preform and / or is separated from the edge 740 of the fiber preform by other fiber layers. The second surface 814 directly covers the other fiber layers, or is covered by these other fiber layers. In particular, when the fiber layer 80 comprises a plurality of fiber layers stacked one on top of another, the first surface 812 of some of the fiber layers may be the first surface 812 directly covering the edge 740, and one of the stacked fiber layers (e.g., the layer furthest from axis B) may be separated from the edge 740 by other fiber layers arranged between the edge 740 and the stacked fiber layers.

[0102] Figures 8 to 12 A preferred embodiment is shown, wherein the fiber layer 80 may include a first fiber layer 810 and a second fiber layer 820, and may include a third fiber layer 830 that is at least partially inserted between the first fiber layer 810 and the second fiber layer 820.

[0103] The first fiber layer 810 and the second fiber layer 820 may each have: -Surface 812a, which directly covers the edge 740 of the first surface 812. -The other surface 812b of the first surface 812 is separated from the edge 740 by other fiber layers in the corresponding first fiber layer 810 and second fiber layer 820. - The second surface 814 directly covers the surface 814a of the third fiber layer 830, and / or - Another surface 814b of the second surface 814 is covered by other fiber layers in the corresponding first fiber layer 810 and second fiber layer 820.

[0104] The third fiber layer 830 may only have the second surface 814. Specifically, at least some of the fiber layers in the third fiber layer 830 may include: - Surface 814a of the second surface 814, which may directly cover the first fiber layer 810 or the second fiber layer 820, and / or - Another surface 814b, which may be covered by other fiber layers in the third fiber layer 830.

[0105] Figure 8 A first fiber layer 810 having first surfaces 812, 812a, 812b and second surfaces 814, 814a, 814b, and a third fiber layer 830 having second surfaces 814, 814a, 814b are illustrated in a non-limiting manner. The first surface 812 has a larger extent than the second surface 814. Therefore, the second surface 814 of the fiber layers 810, 820, 830 can extend beyond the edge 740, or in other words, extend in a manner that continues the edge 740.

[0106] refer to Figure 8 The fiber layers in the first fiber layer 810 and the second fiber layer 820 can only be covered by other fiber layers in the corresponding first fiber layer 810 and the second fiber layer 820. Alternatively, fiber layers from the first fiber layer 810 and the second fiber layer 820 can be inserted between two fiber layers from the corresponding first fiber layer 810 and the second fiber layer 820, especially when more than two fiber layers 810, 820 are superimposed on each other.

[0107] exist Figure 8 In the middle, the third fiber layer 830 may not cover the edge 740 of the fiber preform.

[0108] Advantageously, before step (c), the first fiber layer 810 can be directly positioned in the mold M, and after step (c), the second fiber layer 820 can be directly positioned on the edge 740 of the fiber preform 740 or even on the first fiber layer 810, such that the edge 740 of the fiber preform 740 is inserted between the first fiber layer 810 and the second fiber layer 820.

[0109] The third fiber layer 830 can be inserted between the first layer 810 and the second layer 820, and is located next to the edge 740 without covering the edge.

[0110] refer to Figure 9 The first fiber layer 810 can be manually positioned, for example, in the second cavity portion M of the mold M. 80 middle.

[0111] refer to Figure 10 The fiber preform 700 obtained in step (b) can be manually positioned, for example, in the first cavity portion M of the mold M. 700 More specifically, the edge 740 of the fiber preform can be positioned on the first fiber layers 810 such that a portion of these first fiber layers 810 covers a first surface of the edge 740 (particularly at the recess 742), and another portion of these first fiber layers 810 partially forms a corrugated or serrated edge 800. (See reference...) Figure 11 The second fiber layer 820 can be manually positioned, for example, in the second cavity portion M of the mold M. 80 Specifically, the second fiber layer 820 may be positioned on the second surface of the edge 740 of the fiber preform (particularly the recess 742) and on the first fiber layer 810 (particularly at the corrugated or serrated edge 800). The second fiber layer 820 may be superimposed on the first fiber layer 810 such that the edge 740 is at least partially inserted between the first fiber layer 810 and the second fiber layer 820.

[0112] Optionally, the third fiber layer 830 may be inserted between the first fiber layer 810 and the second fiber layer 820 outside the edge 740 of the fiber preform.

[0113] The method may also include step (ii) of adding an adhesive layer 9 between the fiber layer 80 and the edge 740 of the fiber preform 700. This step (ii) may be performed before or during step (i).

[0114] Figure 12 An adhesive layer 9 is shown in a non-limiting manner between the edge 740 of the fiber preform and the fiber layers 810, 820, 830.

[0115] The adhesive layer 9 may be epoxy resin-based. For example, the adhesive layer 9 may be, for example, PR520 type epoxy resin or AF191-M type epoxy resin sold by 3M Company.

[0116] The method may include at least one compaction step for compacting the fiber preform 700 and the fiber layer 80. This compaction step may be performed prior to step (d). The compaction step may be performed during or after step (c) of inserting the fiber preform 700 and the fiber layer 80 into the mold M, wherein the fiber preform 700 and / or the fiber layer 80 may be pre-impregnated or dried.

[0117] As an example, the compaction step allows for the assembly of several fiber layers 80 onto the fiber preform 700, after which a protective film and a waterproof tarpaulin are placed around the mold M. Next, a vacuum is created within the waterproof tarpaulin to apply a predetermined pressure to compact the fiber preform 70 and the fiber layers 80. The compaction step can be carried out over a period of, for example, approximately 15 minutes.

[0118] The compaction step can be repeated every four to five added fiber layers 80 until the desired final number of fiber layers 80 is reached.

[0119] The compaction step helps limit porosity and delamination, and also helps limit the possible height difference (especially between fiber layer 80 and fiber preform 700) that could correspond to a thickness greater than expected.

[0120] When the number of fiber layers 80 is, for example, less than three fiber layers 80 to form a corrugated or serrated edge, a single compaction step may be sufficient.

[0121] When the number of stacked fiber layers 80 is, for example, greater than four fiber layers 80 to form a corrugated or serrated edge, several compaction steps may be required.

[0122] The densification step (d) enables the fiber preform 700 and fiber layer 80, particularly the resin in the polymer matrix, to polymerize or harden to form the blade 7 in the composite material.

[0123] Step (d) can be performed by heating to a temperature between 150°C and 200°C, preferably about 180°C.

[0124] The resin (e.g., the resin injected in step (d) and / or the resin pre-impregnated with fiber layer 80) may be thermosetting or thermoplastic. For example, the resin may be based on epoxy resin, polyepoxide, polyimide, polybismaleimide, polyurethane, polyester, or vinyl ester. Alternatively, the resin may be a LMPAEK® type polymer sold by Victrex.

[0125] Advantageously, the fiber preform 700 can be formed from three-dimensionally woven carbon fibers, and the fiber preform can be embedded in an epoxy resin. The fiber layer 80 can be formed from carbon fibers that are woven and pre-impregnated with HexPIy® 8552 or MTM49-L type resin.

[0126] In the case of pre-impregnated fiber layers 80, and during step (d), the injected resin (e.g., PR520 epoxy resin) enables these fiber layers 80 to bond to the edges 740 of the fiber preform. This injected resin will not impregnate the fiber layers 80 previously impregnated with resin (e.g., HexPIy® 8552 or MTM49-L resin). Heating in step (d), for example to 180°C, enables the injected resin (e.g., PR520 epoxy resin) and the resin impregnating the fiber layers 80 and fiber preform 700 (e.g., HexPIy® 8552 or MTM49-L resin) to polymerize and harden simultaneously.

[0127] With the fiber layer 80 dry, the injected resin (e.g., PR520 epoxy resin) in step (d) can impregnate both the fibers of the fiber layer 80 and the fiber preform 700. Therefore, heating in step (d), for example to 180°C, allows the injected resin (e.g., PR520 epoxy resin) to polymerize and harden simultaneously, thus impregnating both the fiber layer 80 and the fiber preform 700.

[0128] The method may include a final refinement and finishing step (e) for refining and finishing the blade 7. As an example, step (e) may include machining the profile of the blade 7 obtained in step (d) to remove excess length. The excess length removed may be between 10 mm and 30 mm.

Claims

1. A method for manufacturing a rotor blade (7) made of composite material for a turbine engine (10), said turbine engine being particularly for an aircraft. The impeller (7) includes a blade (70) having a leading edge (73), a trailing edge (74), a pressure side (71) and a suction side (72) extending between the leading edge (73) and the trailing edge (74), and the blade (70) further including at least one serrated element (8) on the leading edge (73) and / or the trailing edge (74), the method comprising the following steps: (a) A fiber preform (700) is produced by weaving fibers, the fiber preform being designed to form a portion of the blade (70). (b) The fiber preform (700) is formed and hardened in a preforming tool. (c) Insert the fiber preform (700) into the mold (M), (d) Densify the fiber preform (700) with resin to form the blade (7). Its features are: - Before and / or after step (c), the method further includes step (i) of inserting fiber layers (80) into the mold (M) such that at least a portion of the edges (740) of the fiber preform (700) is covered, the fiber layers (80) having corrugated or serrated edges (800). - During step (d), the fiber layer (80) is also densified by the resin to form the at least one serrated element (8).

2. The manufacturing method according to claim 1, wherein: - Prior to step (c), the first fiber layer (810) is positioned directly in the mold (M), and - Following step (c), the second fiber layer (820) is positioned directly on the edge (740) of the fiber preform or even on top of the first fiber layer (810). The edge (740) of the preform is inserted between the first fiber layer (810) and the second fiber layer (820).

3. The manufacturing method according to claim 2, wherein, The third fiber layer (830) is inserted between the first fiber layer (810) and the second fiber layer (820) and is located next to the edge (740) without covering the edge.

4. The manufacturing method according to claim 1 or 2, wherein, Before or during step (i), the method further includes step (ii) of adding an adhesive layer (9) between the fiber layer (80) and the edge (740) of the fiber preform (700), the adhesive layer being, for example, based on epoxy resin.

5. The manufacturing method according to any one of the preceding claims, wherein, The method further includes step (iii) of cutting the fiber preform (700) prior to step (b) to form a recess (742) in the fiber preform.

6. The manufacturing method according to any one of the preceding claims, wherein, The mold (M) includes at least one cavity, a portion of which has a shape complementary to the corrugated or serrated edge (800) of the fiber layer (80).

7. The manufacturing method according to any one of the preceding claims, wherein, Prior to step (d), the method includes at least one step of compacting the fiber preform (700) and the fiber layer (80).

8. The manufacturing method according to any one of the preceding claims, wherein, The fiber layer (80) is made by weaving fibers or stacking multiple layers of fibers.

9. The manufacturing method according to any one of claims 1 to 8, wherein, Prior to step (d), the fiber preform (700) and the fiber layer (80) are impregnated with resin.

10. The manufacturing method according to any one of the preceding claims, wherein, The resin is thermosetting or thermoplastic, such as epoxy-based resin.

11. The manufacturing method according to any one of the preceding claims, characterized in that, The fiber layer (80) is, for example, pre-impregnated with resin.

12. The manufacturing method according to any one of the preceding claims, characterized in that, The fiber layer (80) has an elongated shape along the edge (740) of the fiber preform (700).

13. The manufacturing method according to any one of the preceding claims, characterized in that, The fiber layer (80) extends over at least 70% of the length of the edge (740) of the fiber preform (700).

14. The manufacturing method according to any one of the preceding claims, characterized in that, At least some of the fiber layers (80) have a first surface (812) and a second surface (814), the first surface directly covering the edge (740) of the fiber preform (700) and / or separated from the edge (740) of the fiber preform (700) by other fiber layers (80), the second surface directly covering or being covered by the other fiber layers (80), and the first surface (812) having a larger extent than the second surface (814).

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