AERONAUTICAL PART INCLUDING A HEATED BLANKET

Abstract

The invention relates to an aeronautical component (9) comprising: - a body made of composite material comprising a polymer matrix and reinforcing fibers embedded in the matrix, and - a heating blanket (12) integrated into the body and connected to a power supply device, characterized in that the heating blanket (12) comprises: - a plurality of electrically conductive layers (13), each electrically conductive layer (13) comprising a support layer (14) having first and second surfaces and carbon nanotubes (15) located on at least one of the first and second surfaces, the carbon nanotubes (15) being parallel to each other and perpendicular to the surface of the support layer (14) on which the carbon nanotubes (15) are located, and - first and second electrical insulation layers (19, 20) between which the electrically conductive layers (13) are arranged. (Shorthand figure: 3)

Description

Title of the invention: AERONAUTICAL PART COMPRISING A HEATED COVER Technical field of the invention

[0001] The invention relates to the field of aeronautical parts subject to risks of frost or ice formation.

[0002] The invention relates in particular to the field of parts for aircraft turbomachinery, which are subject to risks of frost or ice formation. Technical background

[0003] An aircraft turbomachine generally extends along and around a longitudinal axis. It comprises a gas generator which typically includes, from upstream to downstream in the direction of gas flow in the turbomachine, a low-pressure compressor, a high-pressure compressor, a gas combustion chamber, a high-pressure turbine and a low-pressure turbine.

[0004] The rotor of the low-pressure compressor is typically connected to the rotor of the low-pressure turbine via a low-pressure shaft. The rotor of the high-pressure compressor, on the other hand, is connected to the rotor of the high-pressure turbine via a high-pressure shaft.

[0005] The turbomachine further comprises a fan located upstream of the gas generator. The fan comprises a rotor driven in rotation about its longitudinal axis by a fan shaft. The fan further comprises blades extending radially from the disk.

[0006] To limit the mass of turbomachines, it has been proposed to make parts of the turbomachine from organic matrix composite material, also known by the acronym OMC. These composite materials typically comprise a polymer matrix and reinforcing fibers embedded in the matrix.

[0007] Furthermore, among fan turbines, there are enclosed fans and unenclosed fans, also known by the English term "open rotor." Unlike enclosed fans, the blades of unenclosed fans are not surrounded by a fan casing. The absence of such a fan casing further reduces the mass of the turbomachinery.

[0008] Turbomachinery, whether with a shrouded or unshrouded fan, is subject to the risk of ice or frost formation. For example, the turbomachine's components may carry blocks of ice. Such phenomena are particularly disruptive to the turbomachine since they can unbalance its equilibrium by creating, for example, an imbalance. Therefore, there is a risk that ice may penetrate inside the turbomachine and degrade the internal components of the turbomachine by impact.

[0009] To limit the risk of frost or ice formation, it has been proposed to equip the parts with defrosting or anti-icing devices. These devices typically heat the parts on which ice or frost is likely to form. Such devices are typically powered by an energy source that enables them to operate.

[0010] Although the risk of ice or frost formation exists in ducted fan aircraft turbomachinery, the configuration of unducted fan turbomachinery exposes them to a greater risk of ice or frost formation. Furthermore, organic matrix composite parts, due to the insulating nature of the matrix, require more powerful de-icing or anti-icing devices to achieve a surface temperature sufficient to prevent or limit ice or frost formation. However, increasing the power of these devices would necessitate oversizing the de-icing or anti-icing systems, which would directly impact the mass and size of the parts and could degrade the composite parts, which have a lower temperature resistance than metallic parts.

[0011] Furthermore, it is not easy to integrate such a defrosting or anti-icing device into a part made of composite material.

[0012] Therefore, there is a need to provide a part comprising a body made of composite material, for an aircraft turbomachine, which limits the risk of frost or ice formation or which allows de-icing of the part, uniformly over the entire part, while being lightweight, compact and sufficiently powerful. Summary of the invention

[0013] To this end, the invention proposes an aeronautical part comprising:

[0014] - a body made of composite material comprising a polymer matrix and fibers reinforcement embedded in the matrix, and

[0015] - a heating blanket integrated into the body and connected to a device power supply.

[0016] The part is remarkable in that the heating blanket comprises:

[0017] - a plurality of electrically conductive layers, each layer electrically conductive comprising a support layer having first and second surfaces and carbon nanotubes located on at least one of the first and second surfaces, the carbon nanotubes being parallel to each other and perpendicular to the surface of the support layer on which the carbon nanotubes are located, and

[0018] - first and second layers of electrical insulation between which are arranged the electrically conductive layers.

[0019] The heating blanket of the invention therefore incorporates a superposition of vertically aligned carbon nanotube sheets, also known by the English acronym VACNT for "Vertically Aligned Carbon Nanotubes," and support layers, the whole being situated between two layers of electrical insulation. The carbon nanotubes generate heat through the Joule effect. Such vertically aligned carbon nanotubes allow for homogeneous conduction without a preferred direction.

[0020] Thanks to such a structure of the heating blanket, it is possible to provide power adapted to the needs of the parts of the turbomachine by simply adjusting the number of electrically conductive layers.

[0021] Also, the heating blanket, thanks to the vertically aligned carbon nanotubes, makes it possible to provide suitable power while being thin, compact and integrated into the body of the part.

[0022] In addition to the electrical properties of the heating blanket, it has been found that the presence of vertically aligned carbon nanotubes enhances the mechanical properties of the part.

[0023] The invention may comprise one or more of the following features, taken individually or in combination with each other:

[0024] - each support layer comprises electrically insulating fibers, by for example, glass fibers or aramid fibers,

[0025] - the carbon nanotubes are located on both the first and second surfaces of at least some of the support layers,

[0026] - carbon nanotubes of two adjacent electrically conductive layers are in contact with each other,

[0027] - a plurality of layers of reinforcing fibers, the heating blanket being located between two layers of reinforcing fibers,

[0028] - between two and twenty electrically conductive layers, advantageously between two and ten electrically conductive layers, and preferably six electrically conductive layers,

[0029] - the power supply device includes a power bus connected to each of the electrically conductive layers,

[0030] - the heating blanket has a thickness between 0.2 mm and 5 mm, advantageously between 0.5 mm and 2 mm,

[0031] - the first and second layers of electrical insulation each comprise a polymer, preferably thermoplastic

[0032] - the polymer is chosen from polyimides,

[0033] - the polymer of the first and second layers of electrical insulation has a volume resistivity greater than or equal to 1.1012 ohm.cm, as measured at 23°C,

[0034] - the first and second layers of electrical insulation each have a thickness less than or equal to 0.2 mm. Brief description of the figures

[0035] Other features and advantages will become apparent from the following description of non-limiting embodiments of the invention with reference to the accompanying drawings in which:

[0036] [Fig-1] [Fig.1] is a perspective view of an example of a turbomachine aircraft to which the invention can be applied;

[0037] [Fig.2] [Fig.2] is a cross-sectional view of a part equipped with a heated blanket according to the invention;

[0038] [Fig.3] [Fig.3] is another cross-sectional view of the part equipped with a heating blanket according to the invention,

[0039] [Fig.4] [Fig.4] is another cross-sectional view of the part equipped with a heated blanket according to the invention,

[0040] [Fig.5] [Fig.5] is a schematic representation of an electrically conductive layer comprising a support layer bearing vertical carbon nanotubes according to one embodiment,

[0041] [Fig.6] [Fig.6] is a schematic representation of an electrically conductive layer comprising a support layer bearing vertical carbon nanotubes according to another embodiment. Detailed description of the invention

[0042] An example of an aircraft turbomachine 1 according to the invention is shown in [Fig. 1]. The turbomachine 1 is, for example, a turbofan engine.

[0043] The turbomachine 1 extends along a longitudinal axis X. A gas flow F flows into the turbomachine 1.

[0044] For the purposes of the present invention, the terms "upstream" and "downstream" are understood in relation to the direction of flow of the gas flow F in the turbomachine 1 along the longitudinal axis X.

[0045] The terms "radial", "radially", "longitudinally", "axial", "axially", are understood with respect to the longitudinal axis X of the turbomachine 1.

[0046] The terms "internal", "internally", "externally", "externally", are understood in relation to the distance of the longitudinal axis X along a radial axis to the longitudinal axis X.

[0047] The turbomachine 1 comprises, from upstream to downstream, a blower 2 and a gas generator 3. The gas generator 3 comprises, from upstream to downstream, a rectifier 4, a low-pressure compressor, a high-pressure compressor, at least one annular combustion chamber, a high-pressure turbine and a low-pressure turbine.

[0048] Not shown in the illustration, each compressor comprises a compressor rotor and each turbine comprises a turbine rotor. The compressor rotor of the low-pressure compressor is connected to the turbine rotor of the low-pressure turbine by a low-pressure shaft. They form a low-pressure unit.

[0049] The compressor rotor of the high-pressure compressor is connected to the turbine rotor of the high-pressure turbine by a high-pressure shaft (not shown). They form a high-pressure unit.

[0050] The low pressure and high pressure shafts can be centered on the longitudinal axis X and are movable in rotation around the longitudinal axis X. The high pressure shaft is arranged coaxially around the low pressure shaft.

[0051] The blower 2 comprises a disk 5 centered on the longitudinal axis X and blades 6 extending radially from the disk 5 and regularly distributed around the longitudinal axis X. The disk 5 and the blades 6 are rotatable about the longitudinal axis X.

[0052] The fan 2 is particularly advantageously of the unshrouded type, also known by the English expression "open rotor". Unlike shrouded type fans, the fan 2 is not surrounded by a fan casing enclosing the fan blades.

[0053] The stator 3 comprises fixed blades 7 rotating about the longitudinal axis X. The blades 7 are evenly distributed around the longitudinal axis X. They may, for example, have variable pitch. The blades 7 are thus free to rotate about their axis of extension, which extends radially with respect to the longitudinal axis X of the turbomachine 1. The blades 7 of the stator 3 are, for example, supported by a motor housing 8. The motor housing 8 is located downstream of the disk 5 and is connected to it. The motor housing 8 is annular and centered on the longitudinal axis X. It has an aerodynamic shape to facilitate the flow of air downstream of the fan 2.

[0054] The turbomachine 1 preferably has a single, unducted fan, also known by the English acronym USF for "Unducted Single Fan". Unlike turbomachines with a contra-rotating fan, also known by the English acronym CROR for "Contra-Rotating Open Rotor", the fan 2 comprises only a single annular row of movable blades rotating about the longitudinal axis. X. This type of configuration makes it possible to considerably reduce the mass of the turbomachine 1.

[0055] The gas flow F passes through the blower 2 and splits into a primary air flow Fl passing through an annular primary channel located inside the engine casing 8 and a secondary air flow F2 passing through an annular secondary channel located outside the engine casing 8.

[0056] The primary airflow Fl passes through the gas generator, and thus successively through the low-pressure and high-pressure compressors. The compressed primary airflow Fl then passes through the combustion chamber where it is mixed with fuel. The combustion gases then pass through the high-pressure and low-pressure turbines. The energy of the gases is transformed by the turbine rotor of the low-pressure turbine into mechanical energy, which drives the low-pressure shaft and, consequently, the low-pressure compressor.

[0057] The secondary airflow F2 passes through the rectifier 3 which limits the gyration of the secondary flow F2 at the outlet of the fan 2. The secondary airflow F2 generates the majority of the thrust of the turbomachine 1.

[0058] With reference to [Fig. 2], certain parts 9 of the turbomachine 1, such as the disc 5 or the blades 6, 7, comprise a body 10 made of a composite material. The composite material is an organic matrix composite, also known by the acronym CMO. The composite material comprises a matrix and fibers embedded in the matrix. The matrix is ​​polymeric and is selected from thermoplastic or thermosetting polymers. The thermoplastic polymer is for example a polysulfone (PSU) such as a polyphenylene sulfide (PPS) or a polyphenylsulfone (PPSU) or a polysulfone (PSU) or a polyethersulfone (PESU), a polyetherimide (PEI), a polyamide imide (PAI), a polyester, a polyaryletherketone (PAEK) such as a polyetheretherketone (PEEK) or a polyetherketoneketone (PEKK), a polycarbonate (PC), a polyamide (PA), an aromatic polyamide such as a polyphthalamide (PPA), a polyethylene (PE), a polypropylene (PP), or a mixture of these.The thermosetting polymer is, for example, a polyester, a polyimide such as polybismaleimide (BMI), a phenol-formaldehyde, or an epoxy. The fibers are, for example, carbon fibers, glass fibers, or aramid fibers, or a mixture thereof. Preferably, the fibers are carbon fibers and the matrix comprises an epoxy.

[0059] Composite materials have the advantage of reducing the mass of parts 9 and therefore of the turbomachine 1 while exhibiting good mechanical properties.

[0060] The composite material advantageously comprises a plurality of fiber plies 11. The fiber plies 11 are either unidirectional or woven. Preferably, each fiber plies 11 is woven.

[0061] The body 10 further has a surface 10a swept by a flow of cold air, such as the secondary air flow F2, which is capable of forming frost or ice.

[0062] Indeed, the parts 9 of the turbomachine 1, such as the disc 5 or the blades 6, 7, are particularly susceptible to the formation of frost or ice due to the flow of cold air sweeping over them. The formation of frost or ice can create an imbalance and destabilize the turbomachine 1. Also, frost or ice formed on these parts 9 can enter the gas generator and cause damage.

[0063] The parts 9 can be any type of part subject to a risk of frost or ice such as a tail assembly, an air inlet nozzle in the turbomachine 1 or the leading edge of aircraft wings.

[0064] In order to prevent the formation of ice or frost and / or to remove ice or frost that has formed, at least some of the parts 9, such as the disc 5 or the blades 6, 7 of the turbomachine 1, or the tail assembly, the air inlet nozzle, the leading edge of aircraft wings, include a heating blanket 12 which is integrated into the body 10 of the part 9. Particularly preferred, the heating blanket 12 is arranged in a sandwich between two layers of fibers 11. Even more preferably, the heating blanket 12 is located between the layer of fiber 1a adjacent to the surface 10a swept by the cold airflow and the next layer of fiber 11b.

[0065] With reference to Figures 3 and 4, the heating blanket 12 comprises electrically conductive layers 13. The heating blanket 12 comprises between 2 and 20 electrically conductive layers 13, advantageously between 2 and 10 electrically conductive layers 13, and preferably 6 electrically conductive layers 13. Each electrically conductive layer 13 comprises a support layer 14 and carbon nanotubes 15.

[0066] Each support layer 14 has first and second surfaces 16, 17 opposite and parallel to the surface 10a of the part 9. Each support layer 14 has a thickness, for example, between 0.05 mm and 5 mm. The thickness of the support layers 14 is measured in a direction perpendicular to the first and second surfaces 16, 17.

[0067] Each support layer 14 is electrically insulating. According to an advantageous embodiment of the invention, each support layer 14 comprises electrically insulating fibers such as glass fibers or aramid fibers or polyester or polyamide or rayon fibers. The glass fibers are, for example, woven or non-woven. Glass fibers have the advantage of being flexible.

[0068] Carbon-15 nanotubes have a substantially tubular shape extending along a Y-axis. According to the invention, the Y-axes of the carbon-15 nanotubes are parallel to each other and perpendicular to at least one of the first and second surfaces 16, 17. Carbon-15 nanotubes are said to be "vertically aligned" and are also known by the English acronym VACNT for "Vertically Aligned Carbon Nanotubes". The Y-axis of each carbon-15 nanotube is also perpendicular to the elongation axis of the fibers 11 of the body 10 and of the glass fibers of the support layer 14.

[0069] Carbon nanotubes 15 can be single-walled, also known by the English acronym SWCNT for "Single Wall Carbon Nanotubes" or multi-walled, known by the English acronym MWCNT for "Multi Wall Carbon Nanotubes" or a combination of these.

[0070] Each carbon-15 nanotube can exhibit an electrical conductivity, as measured at 20°C, of ​​between 10⁴ S.m⁻¹ and 10⁷ Sm⁻¹, and a thermal conductivity, as measured at 20°C, of ​​between 200 Wm⁻².K⁻¹ and 6600 Wm⁻².K⁻¹.

[0071] Carbon nanotubes 15 may have a height less than the thickness of the support layers 14. Carbon nanotubes 15 may have a height, for example, between 1 pm and 100 pm as measured along their elongation axis Y.

[0072] Carbon nanotubes 15 can be functionalized. Functionalizing carbon nanotubes 15 improves their bond with the support layer 14.

[0073] The carbon nanotubes 15 are located on at least one of the first and second surfaces 16, 17 of the support layer 14. The carbon nanotubes 15 are regularly distributed on at least one of the first and second surfaces 16, 17 of the support layer 14.

[0074] According to the example of [Fig.5], the carbon nanotubes 15 are located on one of the first or second face 16, 17 of the support layer 14.

[0075] According to the example of [Fig.6], the carbon nanotubes 15 are located on both the first face 16 and the second face 17 of the support layer 14.

[0076] Preferably, the electrically conductive layers 13 of the heating blanket 12 comprise a combination of the examples of electrically conductive layers 13 shown in Figures 5 and 6. In particular, the electrically conductive layers 13 comprise two electrically conductive layers 13a, 13b, each comprising carbon nanotubes 15 located on one of the faces of the support layers 14, the faces being opposite each other. These two electrically conductive layers 13a, 13b are outer layers. The electrically conductive layers 13 further comprise at least one, and preferably a plurality of intermediate electrically conductive layers 13c each comprising carbon nanotubes 15 located on both faces of the support layers 14, these intermediate electrically conductive layers 13c being located between the two electrically conductive layers 13a, 13b.

[0077] The carbon nanotubes 15 of two adjacent electrically conductive layers 13 are in contact with each other, and therefore in a direction parallel to the Y axis of the carbon nanotubes 15. The carbon nanotubes 15 of an electrically conductive layer 13 are thus in contact with the carbon nanotubes 15 of an adjacent electrically conductive layer 13.

[0078] Furthermore, the heating blanket 12 is connected to a power supply device. The power supply device typically comprises an electrical power source connected to the heating blanket 12. The electrical power source is capable of delivering an electrical voltage between 100V and 1000V, preferably 800V.

[0079] According to a preferred embodiment illustrated in Figures 3 and 4, the power supply device comprises a power bus 18 connected to the electrical power source and to each conductive layer 13. The power bus 18 allows the electrically conductive layers 13 to be connected in parallel. The power bus 13 comprises electrical terminals 18a, 18b connected to each end of the electrically conductive layers 13. In particular, the electrical terminals 18a, 18b are connected to the carbon nanotubes 15 at the ends of the electrically conductive layers 13.

[0080] Given the electrical resistivity of carbon-15 nanotubes, the latter heat up by Joule effect and therefore generate heat.

[0081] According to the invention, the heating blanket 12 further comprises first and second layers of electrical insulation 19, 20 between which are located the electrically conductive layers 13.

[0082] Each electrical insulation layer 19, 20 comprises an electrically insulating material, such as a polymer. The electrically insulating material may have a volume resistivity, measured at 23°C, greater than or equal to 1 × 10¹² ohm·cm, preferably greater than or equal to 1 × 10¹⁵ ohm·cm, in particular 1 × 10¹⁷ ohm·cm. Preferably, each electrical insulation layer 19, 20 comprises a polymer material, preferably thermoplastic. The thermoplastic polymer material is preferably a polyimide. Preferably, each electrical insulation layer 19, 20 is in the form of a polyimide film such as the commercial Kapton film.

[0083] Each layer of electrical insulation 19, 20 preferably has a thickness less than or equal to 0.2 mm, preferably less than 0.1 mm, in particular 0.05 mm.

[0084] The heating blanket 12 has a thickness e of between 0.2 mm and 5 mm, advantageously between 0.5 mm and 1.5 mm. The thickness e is measured along a direction parallel to the Y-axis of the carbon nanotubes 15.

[0085] The heating blanket 12 has a thermal power between 0.25 W / cm2 and 10 W / cm2, preferably between 1 W / cm2 and 5 W / cm2.

[0086] A method for manufacturing part 9 according to the invention will now be described. Part 9 can be manufactured by a draping process. The process comprises the following steps:

[0087] (a) drape at least a first layer of fibres 11 in a mold,

[0088] (b) arrange the heating blanket 12 in the mold,

[0089] (c) drape at least one other layer of fibres 11 in the mold.

[0090] Step (a) may be preceded by a step of supplying a composite substrate made by resin transfer molding for example.

[0091] In step (a) and step (c), the fibre web(s) 11 are preferably pre-impregnated with a resin.

[0092] Step (b) may include the following substeps:

[0093] (bO) arrange the first layer of electrical insulation 19 in the mold,

[0094] (bl) arrange the electrically conductive layers 13 in the mold, and

[0095] (b2) arrange the second layer of electrical insulation 20 in the mold.

[0096] According to this example, the process may include a step (d) after step (c) of Resin polymerization.

[0097] Step (d) can be carried out in an autoclave or in a heated mold, under a press for example or under a vacuum bag.

[0098] The polymerization of the resin can be carried out at a temperature between 50 °C and 200 °C, preferably between 100 °C and 180 °C.

Claims

Demands

1. An aeronautical component (9) comprising: - a body (10) made of a composite material comprising a polymer matrix and reinforcing fibers embedded in the matrix, and - a heating blanket (12) integrated into the body (10) and connected to a power supply device, characterized in that the heating blanket (12) comprises: - a plurality of electrically conductive layers (13), each electrically conductive layer (13) comprising a support layer (14) having first and second surfaces (16, 17) and carbon nanotubes (15) located on at least one of the first and second surfaces (16, 17), the carbon nanotubes (15) being parallel to each other and perpendicular to the surface (16, 17) of the support layer (14) on which the carbon nanotubes (15) are located, and - first and second electrical insulation layers (19, 20) between which the layers are arranged electrically conductive (13).

2. Part according to the preceding claim, characterized in that each support layer (14) comprises electrically insulating fibers, for example glass fibers or aramid fibers.

3. Part according to any one of the preceding claims, characterized in that the carbon nanotubes (15) are located on both the first and second surfaces (16, 17) of at least some of the support layers (14).

4. Part according to any one of the preceding claims, characterized in that the carbon nanotubes (15) of two electrically conductive layers (13) adjacent are in contact with each other.

5. A part according to any one of the preceding claims, characterized in that it comprises a plurality of reinforcing fibre layers (11), the heating blanket (12) being located between two reinforcing fibre layers (11).

6. A component according to any one of the preceding claims, characterized in that the heating blanket (12) comprises between 2 and 20 electrically conductive layers (13), advantageously between 2 and 10 electrically conductive layers (13), and preferably 6 electrically conductive layers (13).

7. Part according to any one of the preceding claims, characterized in that the power supply device comprises a power bus (18) connected to each of the electrically conductive layers (13).

8. Part according to any one of the preceding claims, characterized in that the heating blanket (12) has a thickness between 0.2 mm and 5 mm, advantageously between 0.5 mm and 2 mm.

9. A part according to any one of the preceding claims, characterized in that the first and second layers of electrical insulation (13) each comprise a polymer, preferably thermoplastic.

10. Part according to the preceding claim, characterized in that the polymer is selected from polyimides.

11. Part according to any one of claims 9 or 10, characterized in that the polymer of the first and second layers of electrical insulation (13) has a volume resistivity greater than or equal to 1.1012 ohm.cm, as measured at 23°C.

12. Part according to any one of the preceding claims, characterized in that the first and second layers of electrical insulation (13) each have a thickness less than or equal to 0.2 mm.

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