BR102022020849A2 - MULTI-LAYER HEATING STRUCTURE FOR CONTROLLING ICE ACCUMULATION ON AN AIRCRAFT SURFACE, AND METHOD FOR FORMING A MULTI-LAYER HEATING STRUCTURE FOR CONTROLLING ICE ACCUMULATION ON AN AIRCRAFT SURFACE - Google Patents

Abstract

It is a multi-layer heating structure to control ice build-up on an aircraft surface that includes a carbon nanotube (CNT) heater. The heater includes: a layer of CNT; a first encapsulation layer disposed on a first side of the CNT layer formed of a first encapsulation layer thermoplastic material; and a second encapsulation layer disposed on a second side of the CNT layer formed of a second encapsulation layer thermoplastic material.

Description

MULTI-LAYER HEATING STRUCTURE TO CONTROL ICE ACCUMULATION ON AN AIRCRAFT SURFACE, AND METHOD FOR FORMING A MULTI-LAYER HEATING STRUCTURE TO CONTROL ICE ACCUMULATION ON AN AIRCRAFT SURFACE CROSS-REFERENCE TO RELATED ORDERS

[001] This application claims the benefit of US Provisional Application No. 63/256,673, filed on October 18, 2021, the disclosure of which is incorporated into this document by way of reference, in its entirety.

FUNDAMENTALS

[002] The present invention relates to ice protection systems and, more specifically, to an ice protection device that includes carbon nanotubes integrated into a thermoplastic composite structure.

[003] Aircraft may be exposed to weather conditions that allow ice to form on their surfaces. Ice can form on aircraft surfaces such as the windshield, wings, tail, and air intake components before or during flight. Ice buildup can lead to adverse operations, such as blocking necessary engine airflow or inhibiting the operation of wings or other components. In addition, damage to other components and the safety of the aircraft and passengers can occur. Aircraft equipped with heating components may include electrical heaters to protect the aircraft. There may be a need to ensure proper functioning of heating components during the life of the aircraft.

[004] Carbon nanotubes (CNTs) are allotropes of carbon with a generally cylindrical nanostructure and have a variety of uses in nanotechnology, electronics, optics, and other material sciences. CNTs are thermally and electrically conductive. Due to these properties, CNTs can be used as heaters to prevent icing on aircraft or other vehicles.

[005] CNT heater blankets or other more standard etched sheet metal or wire-wound heater blankets are typically manufactured from thermosetting materials. This construction typically leads to a multi-step curing process, leading to high manufacturing costs. Typical materials also have lower temperature limits, which can lead to design limitations. This construction is typically thicker than necessary, which places a greater demand on energy. These materials also do not allow the heater mantle to be repaired and require replacement.

BRIEF DESCRIPTION

[006] A multilayer heating structure for controlling ice accumulation on an aircraft surface is disclosed in one embodiment. The structure includes: a carbon nanotube (CNT) heater comprising: a layer of CNT; a first encapsulation layer disposed on a first side of the CNT layer formed of a first encapsulation layer thermoplastic material; and a second encapsulation layer disposed on a second side of the CNT layer formed of a second encapsulation layer thermoplastic material.

[007] In addition to one or more of the features described above, or as an alternative to any of the above embodiments, the structure may also include: a front composite structure including a front composite structure thermoplastic material disposed on the first side of the CNT heater ; and a rear composite structure including a thermoplastic composite back structure material disposed on the first side of the CNT heater.

[008] In addition to one or more of the features described above, or as an alternative to any of the above embodiments, the front and rear composite structure thermoplastic materials are the same thermoplastic material.

[009] In addition to one or more of the features described above, or as an alternative to any of the above embodiments, the thermoplastic materials of the front and rear composite structure are the same as the thermoplastic material of the thermoplastic materials of the first and second encapsulation layers.

[0010] In addition to one or more of the features described above, or as an alternative to any of the above embodiments, the rear composite structure can directly contact the second encapsulation layer. Alternatively, the rear composite structure can be spaced apart and not directly contact the second encapsulation layer.

[0011] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the CNT layer may include carbon nanotubes in a silicon composite.

[0012] In addition to one or more of the features described above, or as an alternative to any of the above embodiments, the CNT layer may additionally include one or more layers of metal.

[0013] Also disclosed is a second multilayer heating structure for controlling ice accumulation on an aircraft surface that includes: a carbon nanotube (CNT) heater; a front composite structure including a thermoplastic composite structure disposed on the first side of the CNT heater; and a composite back structure including a thermoplastic composite back structure material disposed on the second side of the CNT heater.

[0014] In addition to one or more of the features described above relating to the second structure, or as an alternative to any of the above embodiments, the front and rear composite structure thermoplastic materials may be the same thermoplastic material.

[0015] In addition to one or more of the features described above in relation to the second structure, or as an alternative to any of the previous embodiments, the thermoplastic materials of the front and rear composite structure can be the same as the thermoplastic material of the thermoplastic materials of the first and rear second layers of encapsulation.

[0016] In addition to one or more of the features described above relating to the second structure, or as an alternative to any of the above embodiments, the CNT heater includes a CNT layer that includes carbon nanotubes in a silicon composite.

[0017] In addition to one or more of the features described above with respect to the second structure, or as an alternative to any of the above embodiments, the CNT layer additionally includes one or more layers of metal.

[0018] The training method of the two modalities above is also disclosed. The method may include: receiving a carbon nanotube (CNT) heater comprising: a CNT layer, a first encapsulation layer disposed on a first side of the CNT layer formed of a first encapsulation layer thermoplastic material a second layer encapsulation disposed on a second side of the CNT layer formed by a thermoplastic material of the second encapsulation layer; receiving a front composite structure including a thermoplastic front composite structure material; arranging the front composite structure on the first side of the CNT heater; receiving a composite back structure including a thermoplastic composite back structure material; arranging the rear composite structure disposed on the second side of the CNT heater to form an assembly including the CNT heater, the front composite structure and the rear composite structure; and heating the assembly to at least partially fuse the front and rear composite thermoplastics and the first and second thermoplastic encapsulation layers adhered thereto together.

[0019] In addition to one or more of the features described above relating to the method, or as an alternative to any of the foregoing embodiments, the heating includes providing heat with the CNT heater.

BRIEF DESCRIPTION OF THE FIGURES

[0020] The following descriptions should not be considered limiting under any circumstances. With reference to the accompanying drawings, similar elements are similarly numbered: Figure 1 is a perspective view of an aircraft showing different locations where a de-icing assembly for embodiments herein may be used; Figure 2 shows an exploded view of a structure with incorporated CNT heating elements according to one embodiment; Figure 3 shows a cross-sectional view of a portion of the CNT heater shown in Figure 2; Figure 4 shows a cross-sectional view of a portion of the assembly shown in Figure 2; Figure 5 shows an exploded view of a structure with incorporated CNT heating elements according to an embodiment including addition layers with respect to Figure 2; Figure 6 shows a cross-sectional view of a portion of the assembly shown in Figure 5; Figure 7 shows an exploded view of a structure with incorporated CNT heating elements according to an embodiment that includes only one of the additional layers of Figure 5; Figure 8 shows an exploded view of a structure with incorporated CNT heating elements according to an embodiment that includes only one different from the additional layers of Figure 5; and Figure 9 shows an exemplary sensor layer according to one embodiment.

DETAILED DESCRIPTION

[0021] A detailed description of one or more embodiments of the disclosed apparatus and method is presented herein by way of example and not limitation with reference to the Figures.

[0022] According to an embodiment, a heater blanket is disclosed. The blanket includes carbon nanotube heating elements in a blanket that is bonded internally within a thermoplastic frame.

[0023] Figure 1 is a perspective view of the aircraft 10 including wings 12, horizontal stabilizers 14 and fuselage 16. Wings 12 include leading edges 18 and horizontal stabilizers 14 include leading edges 20. Of course, the aircraft may also include vertical stabilizers and the teachings here are also applicable to them.

[0024] In the configuration illustrated in Figure 1, the aircraft 10 has a fixed-wing design. Fuselage 16 extends from nose section 22 to tail section 24, with wings 12 attached to fuselage 16 between nose section 22 and tail section 24. Horizontal stabilizers 14 are attached to fuselage 16 in tail section 24. The wings 12 and horizontal stabilizers 14 function to create lift and prevent pitch, respectively, for the aircraft 10. The wings 12 and horizontal stabilizers 14 include critical suction surfaces, such as upper surfaces 26 of the wings 12 and surfaces bottoms 28 of the horizontal stabilizers 14, where flow separation and loss of lift can occur if icing conditions form on any of the surfaces of the wings 12 and horizontal stabilizers 14. Figure 1 also shows structures with heating elements of Embedded CNTs 30 mounted on the leading edges 18 of the wings 12 and on the leading edges 20 of the horizontal stabilizers 14. In other non-limiting embodiments, structures with incorporated CNT heating elements 30 can be mounted on any leading edge surface or non-attack edge of the aircraft 10. Structures with incorporated CNT heating elements 30 function by generating heat in order to prevent the formation of ice or the detachment of ice formed on any of the surfaces mentioned above. Also, it should be noted that the assemblies can be mounted on a flange of the engine and engine induction defrosters usually shown by part number 31.

[0025] In more detail, and as shown in Figure 2, there is provided in one embodiment, a multilayer structure 200 that includes a heater mantle 202. In one embodiment, the heater mantle is formed and a carbon nanotube heater ( CNT).

[0026] With reference also to Figure 3, which shows a more detailed version of the CNT heater 202 of the structure of Figure 2. As illustrated, the CNT heater 202 includes a heating layer 300.

[0027] In a non-limiting example, the heating layer 300 includes at least one sheet of a carbon allotrope material, such as carbon nanotubes (CNT), which have a generally cylindrical structure. A CNT sheet can be formed from CNT suspended in a matrix, a dry CNT fiber or a CNT yarn, to name a few non-limiting examples. In other embodiments, the CNT heater 202 carbon allotrope material includes graphene, graphene nanoribbons (GNRs) or other suitable carbon allotropes. Graphene has a two-dimensional honeycomb lattice structure, and GNRs are graphene strips with ultrathin widths.

[0028] Furthermore, it should be noted that the heating layer 300 may be a heating assembly that includes several layers. Layer 300 may include, for example, the structure as disclosed in US Patent No. 11,167,856 which includes a composite of CNT and silicon surrounded by layers of metal. US Patent No. 11,167,856 is incorporated herein by reference.

[0029] As illustrated, the CNT heater 202 also includes first and second (or front and rear) encapsulation layers 304, 306. The encapsulation layers are formed of a thermoplastic material. Examples of such materials that become molten when heated, solid when cooled, and can be remelted or reshaped after cooling. The curing process is completely reversible, not compromising the physical integrity of the material.

[0030] Prior art CNT heaters typically use thermosetting materials. In contrast to the encapsulation layers 304, 306 shown in Figure 3, the use of thermoset materials will create irreversible chemical bonds during cure. As such, a thermosetting material cannot be melted/reversed, and this current state of the art makes repairing a heater or assembly difficult, if not impossible.

[0031] Examples of materials that can be used as thermoplastic dielectric encapsulation layers 304, 306 include, but are not limited to, polyether ether ketone (PEEK), thermoplastic polyimide or polyaryl ketone (PAEK).

[0032] It should be understood that because the thermoplastic encapsulation layers 304, 306 can be heated and reformed, if there is damage to them or the heating layer 300, the combination thereof can be heated and separated.

[0033] Referring now to Figures 2 and 4, an embodiment of a multilayer structure including a CNT heater 202 is illustrated. In this embodiment, the CNT heater 202 is surrounded by composite structures 402, 404. The composite structures 402, 404 404 may be formed from a thermoplastic in one embodiment. In one embodiment, the composite structures 402, 404 are formed from the same thermoplastic as the thermoplastic encapsulation layers 304, 306. In another, the composite structures 402, 404 are formed from a different thermoplastic than the thermoplastic encapsulation layers 304, 306.

[0034] The CNT heater 202 can be provided and then connected to the composite structures 402, 404 by adding heat. In one embodiment, part or all of the heat can be provided by the CNT heater.

[0035] The embodiments in this document can reduce the complexity/manufacturing costs and decrease the required energy of the heater blanket during operation. This will also allow the heater blanket to be repaired or replaced rather than having to scrap the entire structural component, thus lowering repair and maintenance costs. Using a thermoplastic structure will also provide higher temperature limits that the heater blanket can operate, which can lessen design constraints. These features can be applied to any of the examples discussed below.

[0036] It should be noted that, although shown as being in direct contact with each other, additional layers or adhesive materials may be disposed between the composite structures 402, 404 and the thermoplastic encapsulation layers 304, 306. Thus, the rear composite structure may directly contacting the encapsulation layer 306 in some cases and being separate from it (eg, not in direct contact).

[0037] As shown in Figure 2 and applicable to all embodiments herein, the composite structures 402, 404 can be formed to have such a shape that they can be applied to any of the surfaces of an aircraft as shown above. The CNT heaters 202 may be formed into a flat or molded mat and then placed in one of the frames 402, 404 and then another of the frames 402, 404 is provided to encapsulate the CNT heater 202. The frame so formed can then be heated to at least partially melt them to bond the assembly together. Thus, one embodiment, a method of forming a structure that includes receiving a carbon nanotube (CNT) heater as disclosed herein. The method can also include receiving a front composite structure 402 that includes a front composite thermoplastic structure material and a rear composite structure 404 that includes a rear thermoplastic composite structure material. The two frames 402, 404 can be placed on opposite sides of the CNT heater 202. Of course, as shown below, other layers or materials can be placed between the CNT heater 202 and the frames 402, 404. , then applied to join the assembly.

[0038] Figure 5 shows another embodiment of a set. This set includes additional optional layers/elements. The elements include sensors located in a sensor layer 501 and the layer includes a low adhesion ice coating layer 520. It should be understood that one embodiment is an assembly 700 that only includes the sensor layer 501 (see Figure 7) and another set 800 may include only the ice low adhesion coating layer 520 (Figure 8).

[0039] As illustrated in Figures 5-7, the sensor layer 501 includes sensors 502 are between the CNT heater 202 and the rear or rear composite structure 404. Obviously, the sensor elements 502 can alternatively be placed between the CNT heater 202 and the front or front composite structure 402.

[0040] In one embodiment, sensors 502 are an array of fiber optic sensors that can detect one or both of temperature and stress/strain in assemblies 500, 600, 700.

[0041] As shown in Figures 5 and 9, the sensors 502 of the sensor layer 501 may include a plurality of temperature sensors 504 and a plurality of strain gauge sensors 506. The sensors 504, 506 may be separate from a cable fiber optic 508 in one embodiment. Each fiber optic cable 508 can include both types of sensors 504, 506, which reduces the amount of additional wires that are required to install the different types of sensors.

[0042] In one or more embodiments of the disclosure, the plurality of sensors 504, 506 are separate from each fiber optic cable 508 and individual readings from sensors 504, 506 on the same fiber optic cable 508 can be processed by, for example , a 550 controller in many ways.

[0043] For example, the controller 550 can process each signal from the corresponding sensors 504, 506 using a known time delay or wavelength. Each of the sensors 504, 506 can be associated with a specific location on the aircraft for mapping. Figure 5 illustrates a fixed number of sensors, however it should be understood that any number of sensors and placement of sensors can be used. Furthermore, although the fiber optic based array of sensors is on a surface of a substrate 550, it can be seen that the sensors can be placed directly on the front or back composite structure 402, 404. Thus, in one embodiment the fiber layer sensor includes a 550 substrate that supports the sensors and otherwise does not.

[0044] As shown, the cables 508 extend in the horizontal direction in Figure 9 and the vertical direction in Figures 5 and 7 to illustrate that either orientation is possible. In the non-limiting example, sensors 504, 506 can be arranged to align with a plurality of zones 210-218 of heater 202 to monitor the various zones. Zones on heater 202 are shown in Figure 2, but may apply to all CNT heaters disclosed in this document and orientation may be vertical or horizontal as shown. Example correspondence for the zones in Figure 2 is shown in Figure 9.

[0045] The ice low adhesion coating layer 520 of Figures 5, 6 and 8 can be any type of coating to which it is difficult for ice to adhere. The ice low adhesion coating layer may comprise polydimethylsiloxane (PDMS), at least one of nanoscale amorphous silica and super hydrophobic nanoparticles, and at least one non-reactive hydrophobic additive and one non-reactive hydrophilic additive. The coating can additionally comprise fluoride. An example of such a layer is described in more detail in US Patent Application Publication No. US20210179276A1 which is incorporated herein by reference.

[0046] Further, the ice low adhesion coating layer 520 may be an antifreeze material where any water passing through does not turn into ice due to the low ice adhesion. An example of such a material may have poor ice adhesion, at least below 1.38 MPa (200 psi (pounds per square inch)), preferably below 0.69 MPa (100 psi) and typically below 0.31 MPa (45 psi). These materials include super-low ice adhesion surfaces promoted by Multiscale Crack Initiator, Slippery Liquid Infusion Nanostructured Surfaces (SLIPS), HygraTek, NanoSonic's HybridShield0 antifreeze coatings, IcePhobic PPG coating, NEI Corporation's NANOMYTE SuperAi, or other materials/coatings with low ice adhesion. Examples and uses are described in more detail in US Patent No. 10,875,632 which is incorporated herein by reference.

[0047] The ice low adhesion coating layer 520 may also include health monitoring capabilities.

[0048] The term “about” is intended to include the degree of error associated with measuring the specific quantity based on the equipment available at the time of filing the order.

[0049] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present disclosure. As used in this document, the singular forms “a”, “a” and “the/the” are intended to also include the plural forms, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising", when used in this specification, specify the presence of certain features, integers, steps, operations, elements and/or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elementary components and/or groups thereof.

[0050] Although the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes can be made and equivalents can be substituted for elements thereof without departing from the scope of the present disclosure. Furthermore, many modifications can be made to adapt a specific situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment described as the best contemplated mode for carrying out this present disclosure, but that the present description will include all embodiments that fall within the scope of the claims.

Claims (15)

A multi-layer heating structure for controlling ice accumulation on an aircraft surface, the structure being characterized in that it comprises: a carbon nanotube (CNT) heater comprising; a layer of CNT; a first encapsulation layer disposed on a first side of the CNT layer formed of a first encapsulation layer thermoplastic material; and a second encapsulation layer disposed on a second side of the CNT layer formed of a second encapsulation layer thermoplastic material. Structure according to claim 1, characterized in that it additionally comprises: a front composite structure including a thermoplastic material of front composite structure disposed on the first side of the CNT heater; and a composite back structure including a thermoplastic composite back structure material disposed on the second side of the CNT heater. Structure according to claim 2, characterized in that the thermoplastic materials of the front and rear composite structure are the same thermoplastic material. Structure according to claim 3, characterized in that the thermoplastic materials of the front and rear composite structure are the same as the thermoplastic material of the thermoplastic materials of the first and second encapsulation layers. Structure according to claim 2, characterized in that the rear composite structure is in direct contact with the second encapsulation layer. Structure according to claim 2, characterized in that the front composite structure is not in direct contact with the second encapsulation layer. Structure according to claim 1, characterized in that the CNT layer includes carbon nanotubes in a silicon composite. Structure according to claim 2, characterized in that the CNT layer additionally includes one or more layers of metal. Multi-layer heating structure for controlling ice accumulation on an aircraft surface, the structure being characterized by the fact that it comprises: a carbon nanotube (CNT) heater; a front composite structure including a thermoplastic composite structure disposed on the first side of the CNT heater; and a composite back structure including a thermoplastic composite back structure material disposed on the second side of the CNT heater. Structure according to claim 9, characterized in that the thermoplastic materials of the front and rear composite structure are the same thermoplastic material. Structure according to claim 10, characterized in that the thermoplastic materials of the front and rear composite structure are the same as the thermoplastic material of the thermoplastic materials of the first and second encapsulation layers. Structure according to claim 9, characterized in that the CNT heater includes a CNT layer that includes carbon nanotubes in a silicon composite. Structure according to claim 12, characterized in that the CNT layer additionally includes one or more layers of metal. A method for forming a multi-layer heating structure to control ice accumulation on an aircraft surface, characterized in that the structure comprises: receiving a carbon nanotube (CNT) heater comprising: a CNT layer, a first encapsulation layer disposed on a first side of the CNT layer formed by a first encapsulation layer thermoplastic material; a second encapsulation layer disposed on a second side of the CNT layer formed of a second encapsulation layer thermoplastic material; receiving a front composite structure including a thermoplastic front composite structure material; arranging the front composite structure on the first side of the CNT heater; receiving a composite back structure including a thermoplastic composite back structure material; arranging the rear composite structure disposed on the second side of the CNT heater to form an assembly including the CNT heater, the front composite structure and the rear composite structure; and heating the assembly to at least partially fuse the front and rear composite thermoplastics and the first and second thermoplastic encapsulation layers adhered thereto together. Method according to claim 14, characterized in that the heating includes supplying heat with the CNT heater; or wherein the thermoplastic materials of the front and rear composite structure are the same thermoplastic material; or wherein the front and back composite structure thermoplastic materials are the same as the thermoplastic material of the thermoplastic materials of the first and second encapsulation layers; or wherein the rear composite structure is in direct contact with the second encapsulation layer; or where the front composite structure is not in direct contact with the second encapsulation layer.

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