Electric heating assembly for de-icing engine blades and method of manufacturing and use thereof

Abstract

This invention relates to the field of engine blade technology, and discloses an electrothermal assembly for engine blade de-icing, its preparation method, and its application. The electrothermal assembly is conformally fitted to the engine blade, with the long side of the engine blade's minor axis parallel to a first direction and a second direction perpendicular to the first direction. The electrothermal assembly includes multiple heating elements arranged sequentially along the second direction and connected in parallel. Each heating element has two second edges opposite to each other in the second direction, and the second edges are parallel to the first direction. The heating element includes a conductive fabric, which comprises a fiber fabric and a graphene electrothermal layer conformally covering the fiber fabric. This electrothermal assembly has good heat distribution uniformity, which is beneficial for improving the de-icing effect of engine blades.

Description

Technical Field

[0001] This invention relates to the field of electric heating device technology, specifically to an electric heating component for de-icing engine blades, its preparation method, and its application. Background Technology

[0002] The powerful suction generated by the high-speed rotation of engine blades can draw in outside air. In cold weather, low-temperature water droplets and / or ice and snow can be drawn into the engine, causing the engine blades to freeze, which in turn affects engine performance and aircraft safety. Metal-based electric heating technology is an effective means of preventing and de-icing engine blades, but the high density of metal-based electric heating materials does not meet the requirements for lightweight aircraft development. Graphene fiber fabrics, on the other hand, have lower density and higher flexibility, which is beneficial for aircraft lightweighting. Graphene fiber fabrics are typically conformal to the engine blades, with positive and negative electrodes positioned at two opposite edges. By applying voltage to the positive and negative electrodes, the graphene fiber fabric heats the engine blades under the Joule effect to perform the anti-icing function.

[0003] However, irregularly shaped engine blades are not rectangular. When irregularly shaped graphene fiber fabric is used to electrically heat the irregularly shaped engine blades as a whole, the heat distribution uniformity of the irregularly shaped graphene fiber fabric is poor, which limits the anti-icing effect of the engine blades and is not conducive to the anti-icing effect of irregularly shaped engine blades. Summary of the Invention

[0004] In view of this, the present invention provides an electrothermal component for engine blade de-icing, its preparation method and application, so as to improve the de-icing effect of engine blades.

[0005] In a first aspect, the present invention provides an electrothermal assembly for de-icing engine blades, the electrothermal assembly being conformally fitted to the engine blades, wherein the long side of the engine blades along the minor axis is parallel to a first direction, and a second direction is perpendicular to the first direction; the electrothermal assembly includes a plurality of heating elements arranged sequentially along the second direction and connected by a parallel circuit, each heating element having two second edges disposed opposite each other in the second direction, the second edges being parallel to the first direction; the heating element includes a conductive fabric, the conductive fabric including a fiber fabric and a graphene electrothermal layer conformally covering the fiber fabric.

[0006] In the aforementioned conformal heating assembly for engine blades, multiple heating elements are connected in parallel circuits, allowing each element to heat up independently. Each heating element has its own corresponding current-priority transmission path, thereby increasing the number of current-priority transmission paths in the heating assembly and improving the uniformity of heat distribution. The temperature difference between the multiple heating elements can be very small or virtually zero, which is beneficial for improving the anti-icing and de-icing effect of the engine blades.

[0007] In some optional embodiments, the length difference between the two second edges of the heating element is 5mm to 15mm. Thus, by controlling the design, fabrication, and assembly difficulty of the heating assembly, the shape of the heating element is made close to rectangular, which helps to improve the heating uniformity of different areas within the same heating element, thereby improving the anti-icing effect of the engine blades.

[0008] In some optional embodiments, the spacing between adjacent heating elements is 0.05mm to 0.1mm. This not only avoids accidental contact between adjacent heating elements and helps maintain the parallel connection of multiple heating elements, but also improves the heating uniformity of different areas of the heating assembly, thereby improving the de-icing effect on different areas of the engine blade surface.

[0009] In some optional embodiments, the heating element has two first edge regions disposed opposite to each other in a first direction; the heating element further includes a first electrode and a second electrode located on the surface of the conductive fabric, the first electrode and the second electrode being located in the two first edge regions respectively, the first electrodes of adjacent heating elements being electrically connected, and the second electrodes of adjacent heating elements being electrically connected. By dividing the heating element into multiple heating elements and setting the first electrode and the second electrode of each heating element in the first edge region, the first electrode and the second electrode in each heating element are approximately parallel to each other, thereby maximizing the consistency of the in-plane electric field intensity of each heating element and improving the heating uniformity of each heating element.

[0010] In some optional embodiments, the heating assembly further includes a first busbar and a second busbar. The first busbar covers and is connected to the first electrodes of the plurality of heating elements, and the second busbar covers and is connected to the second electrodes of the plurality of heating elements. The first and second busbars not only connect the plurality of heating elements into a single unit but also enable parallel connection of the multiple heating elements.

[0011] In some alternative embodiments, the fiber fabric includes one or more of glass fiber fabric, quartz fiber fabric, alumina fiber fabric, silicon carbide fiber fabric, and boron fiber fabric.

[0012] In some alternative embodiments, the thickness of the graphene electrothermal layer is 10 nm to 100 nm.

[0013] In some alternative embodiments, the heating element further includes an encapsulation layer covering the conductive fabric, and the encapsulation layers in the plurality of heating elements are an integral structure.

[0014] Secondly, the present invention provides a method for preparing an electrothermal assembly for de-icing engine blades, comprising:

[0015] The long side of the engine blade in the short axis direction is parallel to the first direction, and the second direction is perpendicular to the first direction. Multiple pre-defined areas of electric heating elements are divided according to the shape and size of the engine blade, and the dividing lines are parallel to the first direction.

[0016] The sheet resistance of each heating element is calculated based on the area of ​​the preset region of each heating element, the height in the second direction and the width of the median line in the first direction, as well as the test voltage and preset power density of the heating assembly. The preset power density of multiple heating elements is the same.

[0017] Based on the size, shape and sheet resistance of a preset area of ​​each heating element, a corresponding heating element is prepared. The heating element includes a conductive fabric, which includes a fiber fabric and a graphene heating layer conformally covering the fiber fabric.

[0018] A plurality of the heating elements are arranged sequentially along a second direction and connected in parallel to form a heating assembly, which is conformal to the engine blades.

[0019] In some optional embodiments, the preset regions of the plurality of heating elements include the preset regions of the first heating element to the Nth heating element, where N is an integer greater than 1 and n is an integer greater than or equal to 1 and less than or equal to N; the sheet resistance of the nth heating element is calculated using the following formula:

[0020]

[0021] In the formula, R n方 S is the sheet resistance of the nth heating element, in Ω / □; U is the test voltage of the heating assembly, in V; S n The area of ​​the preset region of the nth heating element is expressed in m². 2 ;P m The preset power density of the electric heating element, in W / m³. 2 L n The height of the preset area of ​​the nth heating element in the second direction, in meters (m); W n The width of the preset area of ​​the nth heating element in the first direction is the midline width, in meters.

[0022] In some optional embodiments, the preset region of the heating element includes a main heating region and two electrode regions adjacent to the main heating region. The preset region of the heating element has two first edges disposed opposite to each other in a first direction, and the two electrode regions are respectively located at the two first edges. n W represents the area of ​​the main heating zone within the preset region of the nth heating element. n The width of the main heating zone in the preset area of ​​the nth heating element is the width of the midline in the first direction.

[0023] In some optional embodiments, the preparation of the corresponding heating element based on the size, shape, and sheet resistance of the preset region of each heating element includes: forming a corresponding graphene heating layer on the surface of the fiber fabric based on the sheet resistance of each heating element to obtain a corresponding initial conductive fabric; cutting the initial conductive fabric based on the size and shape of the preset region of each heating element to obtain the conductive fabric; forming a first electrode and a second electrode on the surface of the conductive fabric to obtain the heating element; the preset region of the heating element has two first edge regions arranged opposite to each other in a first direction, and the first electrode and the second electrode respectively correspond to the two first edge regions.

[0024] In some optional embodiments, the plurality of heating elements are connected in parallel circuit, including: the first electrode is a metal electrode, a first busbar is sequentially covered over the first electrodes of the plurality of heating elements, and the first busbar is welded to the first electrode; the second electrode is a metal electrode, a second busbar is sequentially covered over the second electrodes of the plurality of heating elements, and the second busbar is welded to the second electrode.

[0025] Thirdly, the present invention provides the application of the electrothermal assembly described in the first aspect in engine blade de-icing. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the specific embodiments or related technologies of the present invention, the drawings used in the description of the specific embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of an electrothermal assembly in an engine blade according to an embodiment of the present invention.

[0028] Figure 2 yes Figure 1 A schematic diagram of the analog circuit of the heating element in the image.

[0029] Figure 3 yes Figure 1 Cross-sectional view of the heating element.

[0030] Figure 4 This is a schematic diagram of the planar structure of an engine blade according to an embodiment of the present invention.

[0031] Figure 5 This is a schematic diagram illustrating the partitioning of engine blades according to an embodiment of the present invention.

[0032] Figure 6This is an infrared image of the electrothermal assembly according to Embodiment 1 of the present invention.

[0033] Figure 7 Infrared image of an engine blade equipped with the electrothermal assembly of Embodiment 1.

[0034] Figure 8 Infrared image of an engine blade equipped with an electrothermal assembly as shown in Comparative Example 1.

[0035] Explanation of reference numerals in the attached figures:

[0036] 100-Heating element; 110-Conductive fabric; 120-First electrode; 130-Second electrode; 200-First busbar; 300-Second busbar; 400-Insulating adhesive layer; 500-Encapsulation layer; 600-Engine blade; 700-Planar model; 710-Preset area. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present invention are shown in the drawings, not the entire structure.

[0038] As described in the background section, when using irregularly shaped graphene fiber fabric for overall electric heating of irregularly shaped engine blades, the heat distribution uniformity of the irregularly shaped graphene fiber fabric is poor. This is because the spacing between the positive and negative electrodes on the irregularly shaped graphene fiber fabric is not constant, and the current preferentially travels from the positive electrode to the negative electrode along the shortest path, resulting in different current transmission patterns in different regions of the graphene fiber fabric, thus leading to poor heat distribution uniformity of the irregularly shaped graphene fiber fabric.

[0039] Based on this, in a first aspect, the present invention provides an electrothermal assembly for de-icing engine blades, the electrothermal assembly being conformally fitted to the engine blades. Figure 1 A schematic diagram of the structure of the electrothermal assembly in the engine blade is shown. Figure 2 A schematic diagram of the analog circuit of the heating assembly is shown. The long side of the engine blade 600 in the minor axis direction is parallel to the first direction, and the second direction is perpendicular to the first direction; the heating assembly includes a plurality of heating elements 100 arranged sequentially along the second direction and connected in parallel, each heating element 100 having two second edges arranged opposite to each other in the second direction, the second edges being parallel to the first direction. Figure 3 It shows Figure 1 The cross-sectional view at point A-A' in the diagram is shown in the reference diagram. Figure 3The heating element 100 includes a conductive fabric 110, which includes a fiber fabric (not shown) and a graphene heating layer (not shown) conformally covering the fiber fabric.

[0040] In the aforementioned conformal electrothermal assembly with the engine blade 600, multiple heating elements 100 are connected in parallel circuits, allowing each heating element 100 to heat up independently. Each heating element 100 has its corresponding current-priority transmission path, thereby increasing the number of current-priority transmission paths in the electrothermal assembly and improving the heat distribution uniformity of the electrothermal assembly. The temperature difference between the multiple heating elements 100 can be very small or essentially zero, which is beneficial for improving the anti-icing and de-icing effect of the engine blade.

[0041] Engine blades have a major axis and a minor axis. The major axis refers to the axis of the blade in its main extension direction, which is usually consistent with the length direction of the blade. The major axis extends roughly from the blade root to the blade tip and is the direction in which the blade bears the main loads such as centrifugal force and airflow impact force. The minor axis is the axis perpendicular to the major axis. Engine blades have a first side and a second side in the minor axis direction. The length of the first side is greater than the length of the second side. The first side is the long side in the minor axis direction of the engine blade.

[0042] In this application, the conformal relationship between the electrothermal assembly and the engine blade means that their shapes and sizes are identical or substantially identical. For example... Figure 1 As shown, for engine blades whose long side and short side are not parallel in the short axis direction, the heating element cannot cover the entire area of ​​the engine blade. However, since the area where the heating element is not installed on the short side is usually small, the heat emitted by the heating element can be diffused to this area to meet the anti-icing requirements of this area.

[0043] The heating element 100 can be trapezoidal, quasi-trapezoidal, or rectangular. In this invention, a quasi-trapezoidal shape refers to a quadrilateral containing a set of parallel opposite sides and a set of non-parallel opposite sides, wherein at least one of the non-parallel opposite sides contains a curved segment.

[0044] The length difference between the two second edges of the heating element 100 can be 5mm to 15mm, such as 5mm, 7mm, 9mm, 11mm, 13mm, 15mm, or any range of the above values. It should be understood that the smaller the length difference between the two second edges of the heating element 100, the closer the shape of the heating element 100 is to a rectangle, and the higher the heating uniformity of different areas of the same heating element 100. However, this results in a larger number of heating elements 100 in the heating assembly, increasing the design, fabrication, and assembly difficulty of the heating assembly. By limiting the length difference between the two second edges of the heating element 100 to the above range, it is not only beneficial to control the design, fabrication, and assembly difficulty of the heating assembly, but also to make the shape of the heating element 100 closer to a rectangle, which helps to improve the heating uniformity of different areas of the same heating element 100, thereby improving the anti-icing effect of the engine blades.

[0045] The spacing between adjacent heating elements 100 can be 0.05mm to 0.1mm, such as 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, or any range of the above values. Adjacent heating elements 100 need to be spaced apart to avoid accidental contact. However, the spaced area between adjacent heating elements 100 cannot generate heat on its own and relies on heat diffusion from the adjacent heating elements 100. By limiting the spacing between adjacent heating elements 100 within the above range, not only can accidental contact between adjacent heating elements 100 be avoided, which is beneficial for maintaining the parallel connection of multiple heating elements 100, but it also helps to improve the heating uniformity of different areas of the heating assembly, thereby improving the de-icing effect on different areas of the engine blade surface.

[0046] The number of heating elements in the heating assembly is determined by the dimension of the engine blade along its long axis, the difference in length between the two second edges of the heating element, and the spacing between adjacent heating elements.

[0047] The fiber fabric includes, but is not limited to, one or more of glass fiber fabric, quartz fiber fabric, alumina fiber fabric, silicon carbide fiber fabric, and boron fiber fabric, preferably glass fiber fabric. The infrared thermal efficiency of the graphene glass fiber fabric is as high as 0.92, which is close to the radiation level of a blackbody, and the emissivity remains stable over a wide wavelength range, thereby providing stable high heat generation.

[0048] In some optional embodiments, the thickness of the graphene electrothermal layer can be 10nm to 100nm, such as 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, or any range of the above values.

[0049] refer to Figure 3The heating element 100 further includes a first electrode 120 and a second electrode 130 located on the surface of the conductive fabric 110. The heating element 100 has two first edge regions arranged opposite each other in a first direction. The first electrode 120 and the second electrode 130 are respectively located in the two first edge regions. The first electrodes 120 of adjacent heating elements are electrically connected, and the second electrodes 130 of adjacent heating elements are electrically connected. By dividing the heating element into multiple heating elements and setting the first electrode and second electrode of each heating element in the first edge region, the first electrode and second electrode in each heating element are approximately parallel to each other, thereby maximizing the consistency of the in-plane electric field intensity of each heating element and improving the heating uniformity of each heating element.

[0050] The first electrode 120 and the second electrode 130 are the positive and negative electrodes, respectively. The first electrode 120 is made of a metal, such as one or more of copper and silver; the second electrode 130 is made of a metal, such as one or more of copper and silver.

[0051] In some optional embodiments, the heating assembly may further include a first busbar 200 and a second busbar 300. The first busbar 200 covers and is connected to the first electrodes 120 of the plurality of heating elements 100, and the second busbar 300 covers and is connected to the second electrodes 130 of the plurality of heating elements 100. The first busbar 200 and the second busbar 300 not only connect the plurality of heating elements 100 into a single unit, but also enable the parallel connection of the plurality of heating elements 100.

[0052] In some alternative implementations, the heating element may further include a first lead electrode and a second lead electrode for connecting to an external power source to apply voltage to the heating element.

[0053] Specifically, the first electrode 120 can be welded to the first busbar 200, or it can be bonded to the first busbar 200 using conductive adhesive, thereby achieving both mechanical and electrical connections between the first electrode 120 and the first busbar 200. The first busbar 200 can be a metal mesh or metal foil, and the material of the first busbar 200 includes, but is not limited to, one or more of copper and silver.

[0054] The second electrode 130 can be welded to the second busbar 300, or it can be bonded to the second busbar 300 with conductive adhesive, thereby achieving mechanical and electrical connection between the second electrode 130 and the second busbar 300. The second busbar 300 can be a metal mesh or metal foil, and the material of the second busbar 300 includes, but is not limited to, one or more of copper and silver.

[0055] The first busbar 200 covers the first electrodes 120 of the plurality of heating elements 100, and the length connected to the first electrodes 120 constitutes a first electrical connector; the length exceeding the plurality of heating elements 100 constitutes a first lead-out electrode. The second busbar 300 covers the second electrodes 130 of the plurality of heating elements 100, and the length connected to the second electrodes 130 constitutes a second electrical connector; the length exceeding the plurality of heating elements 100 constitutes a second lead-out electrode. The first and second electrical connectors are used to realize the parallel connection of the plurality of heating elements 100, and the first and second lead-out electrodes are used to connect to an external power source. The first and second lead-out electrodes can be led out from the same side of the heating assembly or from opposite sides of the heating assembly.

[0056] The width of the first electrical connector can be the same as or substantially the same as the width of the first electrode 120. The thickness of the first electrode 120 can be 50µm-80µm, such as 50µm, 55µm, 60µm, 65µm, 70µm, 75µm, 80µm, or any range of the above values; the width of the first electrode 120 can be 2mm-10mm, such as 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, or any range of the above values. By limiting the width and thickness of the first electrode 120 to the above ranges, the connection between the first electrode 120 and the first electrical connector is facilitated, and the connection strength between the first electrode 120 and the first electrical connector is improved, thereby enhancing the structural stability of the electrothermal assembly.

[0057] The width of the second electrical connector can be the same as or substantially the same as the width of the second electrode 130. The thickness of the second electrode 130 can be 50µm-80µm, such as 50µm, 55µm, 60µm, 65µm, 70µm, 75µm, 80µm, or any range of the above values; the width of the second electrode 130 can be 2mm-10mm, such as 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, or any range of the above values. By limiting the width and thickness of the second electrode 130 to the above ranges, the connection between the second electrode 130 and the second electrical connector is facilitated, and the connection strength between the second electrode 130 and the second electrical connector is improved, thereby enhancing the structural stability of the electrothermal assembly.

[0058] The heating element may further include an insulating layer (not shown) covering the first and second leads to prevent accidental contact between the first and second leads, which could cause a short circuit in the heating element. The insulating layer may be made of one or more of polyimide (PI), polytetrafluoroethylene (PTFE), and polyester resin (PTE).

[0059] refer to Figure 3 The heating assembly may further include an insulating adhesive layer 400 covering the first and second electrical connectors to improve the connection strength between the first and second electrical connectors and the heating element 100, which is beneficial for the stable transmission of current from the external power source to the heating element 100 when the heating assembly is working. Specifically, the insulating adhesive layer 400 may be located on the surface of the first electrical connector facing away from the first electrode 120 and on the surface of the second electrical connector facing away from the second electrode 130.

[0060] In some alternative embodiments, the first electrical connector and the first lead electrode can be provided independently, and the second electrical connector and the second lead electrode can be provided independently. The first lead electrode and the second lead electrode can be wires.

[0061] refer to Figure 3 The heating element 100 may further include an encapsulation layer 500 covering the conductive fabric 110. The encapsulation layer 500 may extend to the side surface of the insulating adhesive layer 400 opposite to the first electrode 120 and the second electrode 130. The encapsulation layer 500 can provide mechanical and chemical protection for the heating element 100, preventing the heating element 100 from being exposed to air and reacting chemically with oxygen and water vapor, which is beneficial to improving the service life of the heating element 100.

[0062] The encapsulation layer 500 includes, but is not limited to, one or more of epoxy resin film, bismaleimide resin film, and phenolic resin film.

[0063] The thickness of the encapsulation layer 500 is 0.08mm to 0.1mm, such as 0.08mm, 0.09mm, 0.1mm, or any range of the above values. By limiting the thickness of the encapsulation layer 500 to the above range, the encapsulation layer 500 has effective encapsulation capability and good flexibility, which is beneficial to improving the adhesion effect of the electrothermal component in the engine blade.

[0064] Optionally, the encapsulation layer 500 in the plurality of heating elements 100 is an integral structure, which can improve the connection strength between the plurality of heating elements 100, thereby improving the structural stability of the heating assembly.

[0065] Secondly, the present invention provides a method for preparing an electrothermal assembly for de-icing engine blades, comprising:

[0066] Step S1: The long side of the engine blade in the short axis direction is parallel to the first direction, and the second direction is perpendicular to the first direction. According to the shape and size of the engine blade, a number of preset areas of electric heating elements are divided, and the dividing lines are parallel to the first direction.

[0067] Step S2: Calculate the sheet resistance of each heating element based on the area of ​​the preset region of each heating element, the height L in the second direction and the width W of the median line in the first direction, as well as the test voltage and preset power density of the heating assembly. The preset power density of multiple heating elements is the same.

[0068] Step S3: Prepare corresponding heating elements based on the size, shape and sheet resistance of the preset area of ​​each heating element. The heating element includes a conductive fabric, which includes a fiber fabric and a graphene heating layer conformally covering the fiber fabric.

[0069] Step S4: Arrange multiple heating elements sequentially along the second direction and connect them in parallel to obtain a heating assembly, wherein the heating assembly is conformal to the engine blade.

[0070] The method for preparing the electrothermal component can be used to prepare the electrothermal component provided in the first aspect. Therefore, the characteristics (such as materials and dimensions) and effects described for the electrothermal component are also applicable to the method for preparing the electrothermal component, and will not be described in detail here.

[0071] In step S1, multiple preset areas of the heating elements are divided according to the shape and size of the engine blades, including:

[0072] Step S11, Reference Figure 4 Based on the shape and size of the engine blade, a planar model 700 of the engine blade is established. The long side of the engine blade in the minor axis direction is parallel to the first direction. The planar model is a model that transforms the three-dimensional curved surface structure into a two-dimensional plane representation, which unfolds the curved surface of the object to form a plane.

[0073] Step S12, Reference Figure 5 The planar model 700 is divided into parallel sections with the dividing lines parallel to the first direction, resulting in multiple pre-defined regions 710 of the heating elements, which are trapezoidal or quasi-trapezoidal. During the division process, it is necessary to ensure that the length difference between parallel opposite sides in the pre-defined region 710 of each heating element is 5mm to 15mm, so that the obtained pre-defined regions 710 of the heating elements are close to rectangles. The pre-defined regions of the multiple heating elements include the pre-defined regions of the first heating element to the Nth heating element, where N is an integer greater than 1 and n is an integer greater than or equal to 1 and less than or equal to N.

[0074] In step S2, the sheet resistance of the nth heating element is calculated using the following formula:

[0075]

[0076] In the formula, R n方 S is the sheet resistance of the nth heating element, in Ω / □; U is the test voltage of the heating assembly, in V; Sn The area of ​​the preset region of the nth heating element is expressed in m². 2 ;P m The preset power density of the electric heating element, in W / m³. 2 L n The height of the preset area of ​​the nth heating element in the second direction can be understood as the height of a trapezoid or quasi-trapezoidal shape, in meters (m); W n The width of the median line of the preset area of ​​the nth heating element in the first direction can be understood as the median line width of a trapezoid or quasi-trapezoidal shape, with the unit being m.

[0077] Power density represents the power per unit area and reflects the degree of energy concentration. In step S2, by limiting the preset power density of multiple heating elements to be the same, it is beneficial to ensure that the actual heat generation per unit area of ​​different heating elements is the same or similar during the operation of the heating assembly, thereby improving the overall heating uniformity of the heating assembly.

[0078] In a preferred embodiment, the preset area of ​​the heating element includes a main heating area and two electrode areas adjacent to the main heating area. The preset area of ​​the heating element has two first edges disposed opposite to each other in a first direction, and the two electrode areas are respectively located at the two first edges. n W represents the area of ​​the main heating zone within the preset region of the nth heating element. n The width of the main heating zone in the preset area of ​​the nth heating element, which is the center line width in the first direction, can further improve the overall heating uniformity of the heating assembly.

[0079] In step S3, a corresponding heating element is fabricated based on the size, shape, and sheet resistance of the preset region 710 of each heating element, including:

[0080] Step S31: Based on the sheet resistance of each heating element 100, a corresponding graphene heating layer is formed on the surface of the fiber fabric to obtain the corresponding initial conductive fabric. The process for forming the graphene heating layer includes, but is not limited to, chemical vapor deposition. The sheet resistance of the heating element 100 can be adjusted by controlling the thickness of the graphene heating layer. The areas of the preset regions 710 of multiple heating elements may be the same or different, therefore the sheet resistance of the multiple heating elements 100 may be the same or different, and correspondingly, the thickness of the graphene heating layer in the multiple heating elements 100 may be the same or different.

[0081] Step S32: Cut the initial conductive fabric based on the size and shape of the preset area 710 of each heating element to obtain the conductive fabric 110; laser cutting technology can be used for cutting.

[0082] Step S33: A first electrode 120 and a second electrode 130 are formed on the surface of the conductive fabric 110 to obtain the heating element 100. The preset region 710 of the heating element has two first edge regions arranged opposite each other in a first direction. The first electrode 120 and the second electrode 130 correspond to the two first edge regions, that is, the first electrode 120 and the second electrode 130 are formed in the two electrode regions respectively. The process of forming the first electrode and the second electrode includes, but is not limited to, a spraying process. The first electrode and the second electrode are formed on the edge regions of the graphene heating layer that are arranged opposite each other and are not parallel.

[0083] In step S4, the multiple heating elements 100 are connected in parallel, including: the first electrode is a metal electrode, the first busbar 200 is sequentially covered with the first electrodes 120 of the multiple heating elements 100, and the first busbar 200 is welded to the first electrodes 120; the second electrode is a metal electrode, the second busbar 300 is sequentially covered with the second electrodes 130 of the multiple heating elements 100, and the second busbar 300 is welded to the second electrodes 130.

[0084] The first busbar 200 extends beyond the length of the multiple heating elements 100 to form a first lead electrode. After welding the first busbar 200 and the first electrode 120, a polymer film can be attached to the surface of the first lead electrode, and an electrical connection terminal for connecting to an external power source can be reserved. After welding the first busbar 200 and the first electrode 120, an insulating adhesive can be coated on the side of the first busbar 200 facing away from the first electrode 120 to form an insulating adhesive layer 400.

[0085] The second busbar 300 extends beyond the length of the multiple heating elements 100 to form a second lead electrode. After welding the second busbar 300 and the second electrode 130, a polymer film can be attached to the surface of the second lead electrode, and an electrical connection terminal for connecting to an external power source can be reserved. After welding the second busbar 300 and the second electrode 130, an insulating adhesive can be coated on the side of the second busbar 300 facing away from the second electrode 130 to form an insulating adhesive layer 400.

[0086] The preparation method of the electric heating component may also include:

[0087] Step S5: After connecting the multiple heating elements 100 in parallel circuit, an encapsulation layer 500 is formed covering the conductive fabric 110. The encapsulation layer 500 of the multiple heating elements 100 is an integral structure. The encapsulation layer 500 can extend to the side surface of the insulating adhesive layer 400 opposite to the first electrode 120 and the second electrode 130.

[0088] An integrated electrically heated composite engine blade is prepared by combining the electric heating components with outer skin material, insulation layer material, and inner skin material through a composite material molding process.

[0089] Thirdly, the present invention provides the application of the electrothermal assembly described in the first aspect in engine blade de-icing.

[0090] Specifically, the electrothermal assembly is disposed in the engine blade, and the structure of the engine blade is as follows: the engine blade includes a first skin and a second skin disposed opposite to each other, and an electrothermal assembly located between the first skin and the second skin and conforming to the first skin and the second skin. The first skin and the second skin can be unidirectional carbon fiber composite laminates.

[0091] The engine blade may also include a first insulating layer located between the first skin and the electrothermal assembly, and a second insulating layer located between the second skin and the electrothermal assembly, wherein the materials of the first insulating layer and the second insulating layer may be glass fiber composite materials.

[0092] The engine blades have electrode leads, and the first lead electrode and the second lead electrode are led out through the electrode leads and electrically connected to an external power source.

[0093] These engine blades can be used in aircraft.

[0094] The following embodiment provides a specific electrothermal component to illustrate the technical effects of this application. This embodiment is merely an example and should not be construed as limiting the scope of protection of this application.

[0095] Example

[0096] This embodiment provides an electrothermal assembly for de-icing engine blades, and its preparation method is as follows:

[0097] Based on the shape and size of the engine blades, a planar model of the engine blades is established. The long side of the planar model corresponding to the minor axis direction of the engine blades is parallel to the first direction.

[0098] See Figure 5 The planar model is divided into parallel sections with the dividing lines parallel to the first direction to obtain multiple pre-defined areas of electric heating elements in the shape of trapezoids or quasi-trapezoidal shapes. During the division process, it is necessary to ensure that the length difference between parallel opposite sides in the pre-defined area of ​​each electric heating element is 5mm~15mm. Six pre-defined areas of electric heating elements are obtained by cutting. Along the long axis of the engine blade, the pre-defined areas are numbered 1#, 2#, 3#, 4#, 5#, and 6# in sequence.

[0099] Measure the area S, height L, and median width W of each preset region. When measuring area S and median width W, the areas for the positive and negative electrodes are excluded. The positive and negative electrode areas are located at the edges of the non-parallel opposite sides of the preset regions, and both the positive and negative electrode areas have a width of 3mm. Combine this with the test voltage U of the heating element and the preset power density P. m Calculate the sheet resistance R of each heating element. n方 The test voltage U was 100V, and the preset power density of the six heating elements was 1000W / m². 2 The parameters for each heating element are shown in Table 1.

[0100] Table 1: Parameters of Heating Components

[0101]

[0102] Based on the sheet resistance of each heating element, a graphene heating layer of corresponding thickness is formed on the surface of the glass fiber fabric to obtain the corresponding graphene glass fiber fabric.

[0103] Based on the size and shape of the preset area of ​​each heating element, the graphene glass fiber fabric is cut using laser cutting technology;

[0104] A positive and negative electrode is formed on the surface of a cut graphene glass fiber fabric using a spraying process. The positive and negative electrodes correspond to the positive and negative electrode setting areas in a preset region, respectively. The material of the positive and negative electrodes is copper, and the thickness of each is 60 μm. Six heating elements are prepared, and each heating element has a number corresponding to the preset region.

[0105] See Figure 1 The six heating elements are arranged in sequence, with the parallel opposite sides of adjacent heating elements being parallel to each other;

[0106] The first busbar sequentially covers the positive electrodes of the six heating elements, and the first busbar is welded to the positive electrodes. The portion of the first busbar extending beyond the six heating elements constitutes the first lead-out electrode. The second busbar sequentially covers the negative electrodes of the six heating elements, and the second busbar is welded to the negative electrodes. The portion of the second busbar extending beyond the six heating elements constitutes the second lead-out electrode. Both the first and second busbars are made of copper mesh.

[0107] Polyimide (PI) is bonded to the surfaces of the first and second leads, with electrical connection terminals reserved for connection to an external power source; silicone is coated on the side of the first busbar facing away from the positive electrode and the side of the second busbar facing away from the negative electrode to form an insulating layer; the two test leads of a multimeter are connected to the electrical connection terminals of the first and second leads, respectively, and the inter-electrode resistance of the heating element is measured to be 343.2Ω.

[0108] A resin layer covering the heating elements was formed using an autoclave process, with the resin layers of the six heating elements connected as a single unit. The thickness of the resin layer ranged from 0.08 mm to 0.1 mm, and the material was epoxy resin. This process yielded a conformal heating assembly for the engine blades. Connecting the two probes of a multimeter to the electrical connection terminals of the first and second leads, respectively, the inter-electrode resistance of the heating assembly was measured to be 354.3 Ω, indicating that the conductive network of the heating assembly remained intact after autoclaving. Compared to before autoclaving, the inter-electrode resistance increased by 3.2% after autoclaving. This is attributed to the epoxy resin impregnating between the graphene glass fiber fabrics during the curing process, reducing the number of connection points between the fabric networks and thus causing a slight increase in resistance.

[0109] Comparative Example

[0110] This comparative example provides an electrothermal assembly for de-icing engine blades, which differs from the embodiment only in that: the electrothermal assembly has only one heating element conformally to the engine blade, and the heating element is made of graphene glass fiber fabric with a sheet resistance of 1396Ω / □.

[0111] Performance testing

[0112] Before and after assembling the heating element into the engine blade, the electrical connection terminals of the first and second leads of the heating element are connected to a power source. The power source applies 100V AC to the heating element. After the heating element stabilizes, an infrared image and maximum temperature difference of the heating element or engine blade are acquired using a PT100 infrared thermal imager. The PT100 infrared thermal imager acquires the infrared radiation energy of the non-contact detection object, converts the infrared radiation energy into an electrical signal, and generates a pseudo-color thermal image and temperature value. It allows for intuitive observation of the infrared image of the detected object and can automatically track the temperature at various points in the image.

[0113] The temperature uniformity of Example 1 was obtained using the above-described temperature uniformity test method: Before assembling the heating element in the engine blades, the infrared image of the heating element in Example 1 was as follows: Figure 6 As shown, the infrared image has a relatively uniform color overall, indicating that the temperature difference between the various heating elements is very small, and the heating assembly heats up evenly. After assembling the heating assembly into the engine blade, the infrared image of the engine blade is as follows. Figure 7 As shown, the infrared image has a relatively uniform color overall, indicating that the engine blades are heated evenly.

[0114] The temperature uniformity of Comparative Example 1 was obtained using the above-described temperature uniformity test method: Before the heating element was assembled into the engine blade, the heating uniformity of the heating element was poor; after the heating element was assembled into the engine blade, the infrared image of the engine blade was as follows: Figure 8 As shown, the upper part of the infrared image is purple and the lower part is bright orange, with a large color difference, indicating that there is a large temperature difference in the engine blades and poor heat uniformity of the engine blades.

[0115] In this document, the term "implementation" means that a specific feature, structure, or characteristic described in connection with an implementation can be included in at least one implementation of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same implementation, nor is it a separate or alternative implementation mutually exclusive with other implementations. It will be explicitly and implicitly understood by those skilled in the art that the implementations described herein can be combined with other implementations.

[0116] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0117] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0118] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0119] The above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described above, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of protection of the present invention is determined by the scope of the appended claims.

Claims

1. An electrothermal assembly for de-icing engine blades, characterized in that, The heating element is conformally fitted to the engine blade, with the long side of the engine blade in the minor axis direction parallel to the first direction and the second direction perpendicular to the first direction. The heating element includes multiple heating elements arranged sequentially along the second direction and connected in parallel. Each heating element has two second edges opposite to each other in the second direction, the second edges being parallel to the first direction, and the difference in length between the two second edges of the heating element being 5mm to 15mm. The heating element includes a conductive fabric, which comprises a fiber fabric and a graphene heating layer conformally covering the fiber fabric. The method for preparing the electrothermal component includes: A planar model of the engine blade is established based on the shape and size of the engine blade, wherein the long side of the planar model corresponding to the minor axis direction of the engine blade is parallel to the first direction; The planar model is divided into parallel sections with the dividing lines parallel to the first direction to obtain multiple preset areas of trapezoidal or quasi-trapezoidal heating elements. The difference in length between parallel opposite sides in the preset areas is 5mm to 15mm. The sheet resistance of each heating element is calculated based on the area of ​​the preset region of each heating element, the height in the second direction and the width of the median line in the first direction, as well as the test voltage and preset power density of the heating assembly. The preset power density of multiple heating elements is the same. The corresponding heating element is prepared based on the size, shape, and sheet resistance of the preset area of ​​each heating element.

2. The electrothermal assembly according to claim 1, characterized in that, The spacing between adjacent heating elements is 0.05mm to 0.1mm.

3. The electrothermal assembly according to claim 1, characterized in that, The heating element has two first edge regions disposed opposite each other in a first direction; the heating element further includes a first electrode and a second electrode located on the surface of the conductive fabric, the first electrode and the second electrode being located in the two first edge regions respectively, the first electrodes of adjacent heating elements being electrically connected, and the second electrodes of adjacent heating elements being electrically connected.

4. The electrothermal assembly according to claim 3, characterized in that, Also includes: A first busbar, the first busbar covering and connected to the first electrodes of the plurality of heating elements; A second busbar covers and is connected to the second electrodes of the plurality of heating elements.

5. The electrothermal assembly according to any one of claims 1 to 4, characterized in that, The fiber fabric includes one or more of the following: glass fiber fabric, quartz fiber fabric, alumina fiber fabric, silicon carbide fiber fabric, and boron fiber fabric. And / or, the thickness of the graphene electrothermal layer is 10nm~100nm; And / or, the heating element further includes an encapsulation layer covering the conductive fabric, and the encapsulation layers in the plurality of heating elements are an integral structure.

6. A method for preparing an electrothermal assembly for engine blade de-icing as described in any one of claims 1 to 5, characterized in that, include: The long side of the engine blade in the short axis direction is parallel to the first direction, and the second direction is perpendicular to the first direction. Multiple pre-defined areas of electric heating elements are divided according to the shape and size of the engine blade, and the dividing lines are parallel to the first direction. The sheet resistance of each heating element is calculated based on the area of ​​the preset region of each heating element, the height in the second direction and the width of the median line in the first direction, as well as the test voltage and preset power density of the heating assembly. The preset power density of multiple heating elements is the same. Based on the size, shape and sheet resistance of a preset area of ​​each heating element, a corresponding heating element is prepared. The heating element includes a conductive fabric, which includes a fiber fabric and a graphene heating layer conformally covering the fiber fabric. A plurality of the heating elements are arranged sequentially along a second direction and connected in parallel to form a heating assembly, which is conformal to the engine blades.

7. The preparation method according to claim 6, characterized in that, The preset regions of the plurality of heating elements include the preset regions of the first heating element to the Nth heating element, where N is an integer greater than 1 and n is an integer greater than or equal to 1 and less than or equal to N. Calculate the sheet resistance of the nth heating element using the following formula: In the formula, R n方 S is the sheet resistance of the nth heating element, in Ω / □; U is the test voltage of the heating assembly, in V; S n The area of ​​the preset region of the nth heating element is expressed in m². 2 ; P m The preset power density of the electric heating element, in W / m³. 2 ; L n The height of the preset area of ​​the nth heating element in the second direction is in meters. W n The width of the preset area of ​​the nth heating element in the first direction is the midline width, in meters.

8. The preparation method according to claim 7, characterized in that, The preset area of ​​the heating element includes a main heating area and two electrode areas adjacent to the main heating area. The preset area of ​​the heating element has two first edges arranged opposite to each other in a first direction, and the two electrode areas are respectively located at the two first edges; S n W represents the area of ​​the main heating zone within the preset region of the nth heating element. n The width of the main heating zone in the preset area of ​​the nth heating element is the width of the midline in the first direction.

9. The preparation method according to claim 6, characterized in that, The process of fabricating corresponding heating elements based on the size, shape, and sheet resistance of a preset region for each heating element includes: Based on the sheet resistance of each heating element, a corresponding graphene heating layer is formed on the surface of the fiber fabric to obtain the corresponding initial conductive fabric. The initial conductive fabric is cut according to the size and shape of the preset area of ​​each heating element to obtain the conductive fabric; The heating element is obtained by forming a first electrode and a second electrode on the surface of the conductive fabric; the heating element has a preset area having two first edge regions arranged opposite each other in a first direction, and the first electrode and the second electrode respectively correspond to the two first edge regions.

10. The preparation method according to claim 9, characterized in that, Connecting multiple heating elements in parallel using a circuit includes: The first electrode is a metal electrode. The first busbar is sequentially covered with the first electrodes of the plurality of heating elements, and the first busbar is welded to the first electrode. The second electrode is a metal electrode. The second busbar is sequentially covered with the second electrodes of the multiple heating elements, and the second busbar is welded to the second electrode.

11. The application of the electrothermal assembly according to any one of claims 1 to 5 in engine blade de-icing.

Images