阅读说明：本技术 用于涡轮发动机内壁的具有特性梯度的涂层 (Coating with property gradient for turbine engine inner wall ) 是由 杰基·诺维·马尔乔诺 阿诺·杜堡 伊迪丝·罗兰·福清 安妮·罗斯 于 2018-12-06 设计创作，主要内容包括：具有特性梯度的涂层,该涂层旨在通过增材制造而固定到安装在涡轮发动机的移动转子叶片的周边处的壳体(46)的内壁上,该涂层包括从涂层的外表面到壳体的该内壁的叠加层,一方面,第一层(54),该第一层(54)由耐磨材料的细丝的三维支架构成,耐磨材料的细丝的三维支架形成孔径在50微米至250微米之间并且孔隙率大于85％的通道或微通道的有序网络,以及另一方面,第二层(52),该第二层(52)具有消散冲击涂层的外表面的声波的能量的功能,并且第二层(52)由第一热固性材料的细丝的三维支架构成,所述第一热固性材料的细丝的三维支架形成孔径在50微米至400微米之间并且孔隙率大于60％的通道或微通道的有序网络。(A coating having a characteristic gradient, the coating being intended to be fixed by additive manufacturing to an inner wall of a casing (46) mounted at the periphery of a moving rotor blade of a turbine engine, the coating comprises superimposed layers from the outer surface of the coating to the inner wall of the housing, on the one hand, a first layer (54), the first layer (54) is constituted by a three-dimensional scaffold of filaments of abrasion-resistant material forming an ordered network of channels or microchannels having a pore size between 50 and 250 microns and a porosity greater than 85%, and, on the other hand, a second layer (52), the second layer (52) has the function of dissipating the energy of the sound waves impacting the outer surface of the coating, and the second layer (52) is constituted by a three-dimensional scaffold of filaments of a first thermosetting material forming an ordered network of channels or microchannels having a pore size between 50 and 400 microns and a porosity greater than 60%.)

1. A property gradient coating intended to be applied by additive manufacturing to the inner wall of a casing (20A, 46) mounted on the periphery of a moving blade of a turbine engine rotor, characterized in that it comprises superimposed layers from the outer surface of said coating to the inner wall of said casing:

a first layer (54), the first layer (54) consisting of a three-dimensional matrix of filaments (100, 102) of a wear-resistant material, the three-dimensional matrix of filaments (100, 102) of a wear-resistant material forming channels or an ordered network of microchannels having a pore size between 50 and 250 microns and a porosity of greater than 85%, and

a second layer (52), the second layer (52) having the function of dissipating energy from acoustic waves impacting the outer surface of the coating, and the second layer (52) consisting of a three-dimensional matrix of filaments (200, 202, 204, 206) of a first thermosetting material, the three-dimensional matrix of filaments (200, 202, 204, 206) of the first thermosetting material forming an ordered network of channels or microchannels having a pore size between 50 microns and 400 microns and a porosity greater than 60%.

2. The property gradient coating of claim 1, wherein the filaments of the first layer are alternately oriented at 0 ° or 90 ° without any shift in the superposition of filaments having the same orientation direction.

3. The property gradient coating of claim 1, wherein the filaments of the second layer are oriented alternately, wherein the orientation directions of these filaments are offset or not offset by the same angular deviation, typically between 20 ° and 40 °.

4. The property gradient coating of any of claims 1 to 3, further comprising a layer of gap-compensating material (64) deposited directly on the inner housing wall to obtain a deposition surface with a known geometry.

5. The property gradient coating according to any of claims 1 to 4, characterized in that it further comprises a third layer (50) having the function of draining the fluid passing through the coating and consisting of a three-dimensional matrix of filaments of a second thermosetting material forming an ordered network of channels or microchannels having a pore size greater than 250 microns and a porosity greater than 70%.

6. The property gradient coating of claim 5, wherein the third layer (50) has a specific pattern of channels that direct fluid passing through the coating to drain to a defined area and having a channel size greater than 500 microns.

7. The property gradient coating of claim 6, wherein the filaments of the third layer are alternately oriented at 0 ° or 90 ° without any shift in the superposition of filaments having the same orientation direction.

8. The property gradient coating according to any of claims 1 to 7, characterized in that it further comprises a fourth layer (48) having a ballistic energy absorbing function caused by unstable impacts, hail ingestion or even blade loss and consisting of a three-dimensional skeleton of filaments of a third thermosetting material forming an ordered network of channels or micro-channels having a pore size of less than 400 microns and a porosity of less than 60%.

9. The property gradient coating of claim 8, wherein the filaments of the fourth layer are alternately oriented at 0 ° or 90 ° and have an offset in the superposition of filaments having the same orientation direction.

10. The property gradient coating of any of claims 1 to 9, further comprising at least one additional layer of wear resistant material added locally on the first layer (54) so as to take into account a non-axisymmetric geometry of the shell.

11. The property gradient coating of any of claims 1 to 10, wherein the wear resistant material is a solvent free thixotropic mixture consisting of a polymer binder and a cross-linking agent and a flow promoting component, wherein the weight ratio of polymer binder to cross-linking agent is between 1:1 and 2: 1; a flow-promoting component, typically petrolatum, is present between 5% and 15% of the total weight of the thixotropic mixture.

12. The property gradient coating of claim 11, wherein the first, second, and third thermoset materials are comprised of the wear resistant material.

13. The property gradient coating of any of claims 1-12, wherein the casing is a turbine engine fan casing of braided composite material.

Background

The present invention relates to the general field of manufacturing parts made of polymeric materials (in particular thermosetting materials), metals, metal alloys or ceramic parts by additive manufacturing, and more particularly, but not exclusively, to manufacturing wear resistant coatings with acoustic functionality, in particular for fan housings.

Control of aircraft noise around airports has become a public health concern. Increasingly stringent standards and regulations are being imposed on aircraft manufacturers and airport managers. As a result, building quiet aircraft has been a strong point of sale for many years. Currently, the noise generated by aircraft engines is attenuated by a local acoustic coating which reduces the sound intensity of the engine over one or two octaves according to the principle of helmholtz resonators. These coatings are usually in the form of composite panels consisting of rigid plates combined with a honeycomb core covered with a perforated skin and arranged at the nacelle or at the upstream and downstream propagation ducts. However, in new generation engines (e.g., in turbofan engines), as in Ultra High Bypass Ratio (UHBR) technology, the area available for acoustic coatings may be significantly reduced. Furthermore, these regions of the composite shell may have shape defects that need to be compensated for by additional machining operations prior to application of the coating.

It is therefore important to propose new methods and/or new materials (in particular porous materials) for eliminating or significantly reducing the noise level generated by the aircraft engine, in particular during the takeoff and landing phases, and over a wider frequency range than the low frequencies currently involved, while maintaining the engine performance. This is why new noise reduction techniques are now being sought to reduce such disturbances and new acoustically treated surfaces, with minimal impact on other functionality of the engine (such as specific fuel consumption), which is a major commercial advantage.

However, fan noise is one of the major contributors to noise pollution in aircraft engines, and the increase in bypass ratios sought by these new generation aircraft intensifies noise pollution.

Furthermore, it is now common and advantageous to produce complex three-dimensional parts easily, quickly, and cost-effectively using additive manufacturing processes instead of traditional casting, forging, or large-scale machining. The aeronautical field is particularly suitable for using these methods. One example is a wire harness deposition (WBD) process.

Disclosure of Invention

The aim of the present invention is to propose a new coating for significantly reducing the noise generated by aircraft turbojet engines, in particular the noise generated by fan-OGV assemblies. One of the objects of the present invention is also to remedy the shape defects caused by the composite nature of the inner wall of the shell to which the coating is applied.

To this end, a property gradient coating is provided, having an inner wall intended to be applied by additive manufacturing to a casing mounted on the periphery of a moving blade of a turbine engine rotor, characterized in that it comprises superimposed layers from the outer surface of said coating to said casing inner wall:

a first layer consisting of a three-dimensional scaffold of filaments of an abrasion resistant material forming a channel or an ordered network of microchannels having a pore size between 50 and 250 microns and a porosity of greater than 85%, and

a second layer having the function of dissipating energy from acoustic waves impacting said outer surface of said coating and consisting of a three-dimensional scaffold of filaments of a first thermosetting material forming an ordered network of channels or microchannels with a pore size between 50 and 400 microns and a porosity greater than 60%.

The result is a porous microstructure with regular and ordered porosity, the properties of which can be fully controlled throughout the thickness of the coating. Depending on the layers used, radial aerodynamic losses are limited, fluid retention is reduced, and sound and ballistic absorption are maximized.

Preferably, the filaments of the first layer are oriented alternately at 0 ° or 90 ° without any offset in the superposition of filaments having the same orientation direction, and the filaments of the second layer are oriented alternately, with or without the orientation direction of the filaments being offset by the same angular offset, typically between 20 ° and 40 °.

According to a contemplated embodiment, the coating may also comprise a layer of gap-compensating material deposited directly on said inner housing wall so as to obtain a deposition surface having a known geometry.

According to the envisaged embodiment, the coating may also comprise a third layer, which has the function of draining the fluid passing through said coating and consists of a three-dimensional scaffold of filaments of a second thermosetting material forming an ordered network of channels or microchannels having a pore size greater than 250 microns and a porosity greater than 70%.

Preferably, the third layer comprises a specific pattern of channels that direct fluid passing through the coating to drain to specific areas and have a channel size greater than 500 microns.

Advantageously, the filaments of said third layer are oriented alternately at 0 ° or 90 ° without any offset in the superposition of filaments having the same orientation direction.

According to contemplated embodiments, the coating may further comprise a fourth layer having ballistic energy absorbing function caused by unstable (unsteady) impacts, hail ingestion or even blade loss, and consisting of a three-dimensional scaffold of filaments of a third thermosetting material forming an ordered network of channels or micro-channels having a pore size of less than 400 microns and a porosity of less than 60%.

Preferably, the filaments of said fourth layer are alternately oriented at 0 ° or 90 ° with an offset in the superposition of filaments having the same orientation direction.

Advantageously, the coating may further comprise at least one additional layer of wear resistant material added locally to said first layer, so as to take into account the non-axisymmetric geometry of said casing.

Preferably, the wear resistant material is a solvent free thixotropic mixture consisting of a polymer binder and a cross-linking agent and a flow promoting component, wherein the weight ratio of polymer binder to cross-linking agent is between 1:1 and 2: 1; the flow-promoting component (typically petrolatum) is present at between 5% and 15% of the total weight of the thixotropic mixture.

Advantageously, the first thermosetting material, the second thermosetting material and the third thermosetting material consist of the wear-resistant material.

Preferably, the housing is a turbine engine fan housing made of a braided composite material.

Drawings

Other features and advantages of the present invention will become apparent from the detailed description given below with reference to the accompanying drawings, which are non-limiting, and in which:

FIG. 1 schematically shows an aircraft turbine engine architecture in which the characteristic gradient coating of the invention is implemented,

figure 2 shows a deposition system of a filamentary material for making the coating according to the invention,

FIG. 3 is an exploded view of a three-dimensional filament support obtained by the system in FIG. 2, an

Fig. 4A to 4D show examples of different layers of the property gradient coating of the invention.

Detailed Description

FIG. 1 is a highly schematic view of an aircraft turbine engine architecture, in this case a turbofan, with a property gradient coating according to the invention applied to one wall of the aircraft.

Generally, such turbofan engine 10 has a longitudinal axis 12 and includes a gas turbine engine 14 and an annular nacelle 16 centered on the axis 12 and concentrically arranged about the engine.

The engine 14 comprises, from upstream to downstream, an air inlet 18, a fan 20, a low-pressure compressor 22, a high-pressure compressor 24, a combustion chamber 26, a high-pressure turbine 28 and a low-pressure turbine 30, each of these elements being arranged along the longitudinal axis 12, according to the direction of flow of the air or gas flow through the turbojet engine. The gases produced by the engine are ejected through a nozzle comprising an annular central body 32 centred on the longitudinal axis 12, an annular primary cowl 34 coaxially surrounding the central body so as to delimit with it an annular flow passage for the primary flow F1, and an annular secondary cowl 36 coaxially surrounding the primary cowl so as to delimit with it an annular flow passage for the secondary flow F2, coaxial with the primary flow passage, and in which a plurality of straightening vanes 38 are arranged (in the exemplary embodiment shown, the turbojet nacelle 16 and the secondary cowl 36 are the same part). The primary and secondary cowl specifically include turbine midbodies 28A and 30A that surround the turbine rotor blades and fan body 20A that surrounds the fan rotor blades.

According to the invention, it is proposed to apply, by additive manufacturing, a property gradient coating in the form of a three-dimensional matrix of filaments of a thermosetting material forming an ordered network of channels between them, onto the inner wall of the casing facing the rotor blade. Depending on the envisaged network structure, the interconnections between the channels may be present in a regular manner when the superposition of the different layers of coating is intended to produce these different channels. The wall is preferably a wall of a turbine engine, for example an aircraft turbojet, which is mounted on the immediate periphery of the rotor blades, and more particularly the inner wall of a fan casing 20A made of a braided composite (preferably 3D), arranged on the periphery of the fan blades. However, deposits on one or more of the turbine housings 28A, 30A are also contemplated, provided of course that the thermoset material on the metal or ceramic substrate has properties suitable for the high temperature environment it will then be subjected to.

FIG. 2 is a schematic diagram of an example of a filamentary material deposition system 40 for making a property gradient coating of the present invention. A graded-characteristic material is defined as a material that involves: a regular variation without discontinuity (undescribed exemplary embodiment) and a stack of several different layers with different characteristics (exemplary embodiment of the invention).

The purpose of this filament deposition system is that the thermosetting material extruded through the ejection nozzle 40A of calibrated shape and size is first deposited on the substrate 46, preferably in combination with pressure and temperature control circuits inside the system, and then successively on the various superimposed layers 48, 50, 52, 54 produced, each having different properties due to its unique structure, until the desired thickness of the coating is obtained.

The filament deposition system 40 follows a deposition path printed by a controlled mechanical assembly 56 (typically a multi-axis (at least 3-axis) machine or, preferably, a robot) controlled by a management unit 58 (typically a microcontroller or microcomputer) to which it is connected, ensuring control of the filament deposition system and controlling both the filament arrangement and the porosity of the obtained coating at any point of the treated surface. Heating lamps or other similar elements 60 mounted proximate the spray nozzle 40A may be used to stabilize the deposited material and prevent creep during deposition.

The thermoset material is fed from a conical extrusion screw 62 which allows the mixing of several components to form a thixotropic viscous paste-like fluid. The conical extrusion screw ensures a sufficient and uniform mixing of the components (throughout the deposition run) to obtain a fluid material with high viscosity to be deposited through the calibrated nozzle. During this run, the generation of bubbles, which form numerous defects in the printing filament and instability of the flow of the fluid material must be avoided; the material must be pushed very gently. It should be noted that with such a tapered extrusion screw having at least two separate inlets 62A, 62B for introducing at least two components simultaneously, a change in the structure of the deposited thermoset material and formation of the different layers 48-54 can be easily achieved by simply controlling the different components introduced sequentially into the tapered extrusion screw.

Fig. 3 shows, in an exploded view, a small portion of a three-dimensional pedestal 70 of filaments 72, 74, 76 (advantageously cylindrical) of thermosetting material that allows the coating of the invention to be made in the form of an ordered network (microgrid) of channels having properties such as to impart a desired gradient of properties to the superimposed layers passing through the coating.

Even further, and as shown in the different configurations of fig. 4A, 4B, 4C and 4D, the coating of the present invention is formed by additive manufacturing superposition from the inner wall to the outer surface of the shell, each of these different layers of material having a given thickness and different structures that give them their respective different characteristics. Each layer of the coating printed by the filament deposition system described above consists of a three-dimensional matrix of filaments of thermosetting material forming an ordered network of channels.

Fig. 4A shows a three-dimensional base frame of filaments 100, 102 intended to form the outer layer 54 of the coating and consisting of a plurality of superimposed filament layers, wherein the filaments of a given layer are alternately oriented at 0 ° or 90 ° without any offset in the superposition of filaments having the same orientation direction.

The purpose of this first layer 54 is to ensure the wear resistance of the coating when the moving blade passes through, in particular during the running-in of the engine, while at the same time meeting the aerodynamic conditions of the turbine engine. To this end, the thermosetting material used for the first layer is a wear-resistant material with a thickness, which forms specific patterns with a certain porosity (percentage of voids), these specific patterns being dimensioned to allow the passage or dissipation of aerodynamic fluctuations (or modifications thereof) and/or acoustic waves. Typically, for filament sizes between 50 and 250 microns, a porosity of greater than 85% is suitable for this wear resistance function. These patterns may also consist of perforations or grooves with a size of less than 1.5mm, which also improves the aerodynamic margin.

The advantage of this wear-resistant function on the surface layer of the coating is to make the rotor-casing assembly compatible with the deformations to which the rotating moving blades are subjected when subjected to the sum of aerodynamic forces and centrifugal forces.

By wear resistant material is meant the ability of the material to dislocate (or erode) during operation in contact with the opposing part (low shear resistance) and its wear resistance after impact by particles or foreign objects it is forced to suck in during operation. Such materials must also maintain or even promote good aerodynamic properties, have sufficient oxidation and corrosion resistance and a coefficient of thermal expansion of the same order as the layer or substrate on which they are deposited, in which case the braided composite forms the housing wall.

Fig. 4B shows a three-dimensional base frame of filaments 200, 202, 204, 206 intended to form the layer 52 of the coating and consisting of superimposed filament layers having, at each layer, a direction of filament orientation that is offset or not offset by the same angular deviation, for example between 20 ° and 40 ° (the inclination value is not limiting).

The purpose of this second layer 52, on which the first layer 54 is deposited, is to ensure dissipation of the energy of the acoustic wave. To this end, the three-dimensional matrix may have channels or microchannels with a pore size typically between 50 and 400 microns and a porosity of greater than 60%. The thermoset material used to make the second layer 52 need not be the wear resistant material used by the first layer 54. However, it is possible to use the same material for the entire coating and avoid having to change its composition between each layer.

Of course, this second layer 52 must withstand mechanical and environmental constraints (particularly associated with particle impact) and maintain the aerodynamic performance of the turbine engine.

Fig. 4C shows a three-dimensional base frame of filaments 300, 302 to form a third layer 50 of coating, consisting of a plurality of superimposed layers of filaments alternately oriented at 0 ° or 90 °, without offset between layers of the same cylindrical filament orientation direction as in the three-dimensional base frame of the first layer 54, but with greater spacing between the filaments, in the example shown on the order of 2 times greater. Typically, for filament sizes greater than 250 microns, a porosity greater than 70% is suitable for this drainage function.

The thermoset material used to make the third layer 50 may or may not be the wear resistant material used by the first layer 54, and may or may not be the same as the material used to make the second layer 52.

The purpose of this third layer 50, on which the second layer 52 is deposited, is to ensure the discharge of the fluid sucked in by the turbine engine and passing through the coating. To do this, the layer with the draining function will advantageously have specific patterns with channels that direct the draining of the fluid towards the advantageous zone (located at the drain pipe from the flow at 6 o' clock) and with channel dimensions greater than 500 microns.

Like the second layer 52, the third layer 50 must withstand mechanical and environmental constraints, particularly those associated with particulate impact, and maintain the aerodynamic performance of the turbine engine.

It should be noted that the presence of this third layer 50 is not necessary, since the draining function can advantageously be ensured by adding a layer with hydrophobic properties located below the first layer 54.

Fig. 4D also shows a three-dimensional base frame of filaments 400, 402 intended to form the fourth and last layer 48 of the coating and consisting of superimposed layers, wherein the filaments of a given layer are alternately oriented at 0 ° or 90 ° and have an offset in the superposition of filaments having the same orientation direction. As shown, the offset is preferably equal to half the distance between two filaments. Typically, for filament sizes less than 400 microns, a porosity of less than 60% is suitable to perform this ballistic function.

The thermoset material used to make the fourth layer 48 may or may not be the wear resistant material used by the first layer 54, and may or may not be the same thermoset material used to make the second layer 52 or the third layer 50.

The final layer 48 is deposited on the shell 46 and the third layer 50 is itself deposited on the final layer 48, the purpose of this final layer 48 being to enhance the mechanical strength of the entire coating and to allow absorption of ballistic energy caused by unstable impact or hail ingestion or even blade loss. This last layer must also be subjected to mechanical and environmental stresses (in particular those associated with particle impact).

It should be noted that, as with the third layer 50, the presence of the rear layer 48 is not necessary, as the energy absorbing function may advantageously be provided within the acoustic layer 52 or directly by the housing 46.

For all these layers it is necessary to ensure adhesion to the previous and/or next layer, which can be directly the shell (compatibility of the coefficients of thermal expansion of the different layers, in particular of the shell materials).

It should be noted that additional interface layers 64 (see fig. 2) may be added prior to the production of these three-dimensional filament pedestals. This is because the fan housing is a woven composite housing whose three-dimensional geometry generally shows deviations from the calculated ideal surface (shape defects), in particular the tendency to form flaps due to the weaving process used, usually of the flexible type (poly-flex). The correction of these defects currently involves complex and expensive operations. It is therefore possible to compensate for play (resin or otherwise) by depositing material by the apparatus in order to obtain a known geometry. The advantage of this preliminary step is the return to a controlled deposition surface that is precisely defined and meets the shape constraints necessary to ensure a good aerodynamic clearance in the engine region of the turbine engine.

It should also be noted that additional layers of wear resistant material may be added locally on the first layer 54 to ensure axial symmetry of the outer surface of the coating. This is because fan housings typically have non-axisymmetric geometries.

The wear resistant material extruded from the calibrated nozzle or nozzles is advantageously a high viscosity thermosetting material (also called fluid) free of solvents whose evaporation produces strong shrinkage as known. The material is preferably a resin in the form of a thixotropic mixture with slow polymerization kinetics and stable filament flow, which therefore has the advantage of a much lower shrinkage between the basic printed matter (just after extrusion of the material) and the final structure (once heated and polymerization is complete).

Examples of abrasion resistant materials used in the context of the method of the present invention are materials in the form of a slurry, which consist of three components, namely a polymer base, such as an epoxy resin (in the form of a blue modelling clay), a cross-linking agent or accelerator (in the form of a white modelling clay) and a translucent pigmented petrolatum (e.g. vaseline (tm)). The accelerator/base component is distributed in a weight ratio of base to accelerator of between 1:1 and 2:1 and petrolatum is present between 5% and 15% (typically 10%) of the total weight of the material. The substrate may further comprise hollow glass microspheres having a defined diameter to ensure the desired porosity while allowing the mechanical properties of the printed base frame to be increased. The advantage of the introduction of petrolatum is the reduction of the resin viscosity and the reaction kinetics of the abrasion resistant material, which makes its viscosity more stable during printing and thus contributes to the flow of the material (viscosity is directly related to the extrusion pressure required to ensure sufficient extrusion speed to maintain print quality).

By way of illustration, this 2:1 ratio gives an abrasion resistant material comprising 1.4g of binder and 0.7g of accelerator to which 0.2g of petrolatum should be added.

For layers other than the first layer 54 and where the thermoset material for all three-dimensional filament pedestals is not a wear resistant material, a metallic or ceramic based material may be effectively used.

The invention therefore allows a fast and stable printing, allowing an efficient reproduction of high performance structures with small filament size and low weight with predetermined functions and controlled characteristics (roughness, aspect ratio, open porosity), which is particularly advantageous in view of the strong constraints encountered in aeronautics.