A thin-film thermoelectric structure for the inner wall of a hypersonic vehicle skin

Abstract

This invention discloses a thin-film thermoelectric structure for the inner wall of a hypersonic vehicle skin, comprising an insulating heat-resistant layer, a thin-film thermoelectric layer, and a phase-change temperature control layer connected in sequence. The insulating heat-resistant layer covers the inner wall of the hypersonic vehicle skin. The thin-film thermoelectric layer contains a thermoelectric functional thin-film assembly, which includes a conductive thin-film layer and a substrate thin-film layer. N-type and P-type thin-film thermoelectric materials are alternately arranged on the substrate thin-film layer to form a thermoelectric thin-film layer. The conductive thin-film layer is disposed on the thermoelectric thin-film layer. A conductive circuit is provided within the conductive thin-film layer. A resistor is externally connected to the substrate thin-film layer. The conductive circuit, resistor, N-type and P-type thin-film thermoelectric materials form a closed circuit. This invention integrates heat protection and thermal energy reuse, designing an aerodynamic heat reuse structure and function, providing more ideas for the design of aircraft thermal protection systems.

Description

Technical Field

[0001] This invention belongs to the field of thermal energy reuse technology for aerospace vehicles and the application of thin film thermoelectric materials, and in particular, a thin film thermoelectric structure for the inner wall of the skin of a hypersonic vehicle. Background Technology

[0002] Hypersonic vehicles generate significant aerodynamic heat during high-speed flight in the dense atmosphere. The development of thermoelectric materials and thermoelectric conversion technology has had a crucial impact on the reuse of this aerodynamic heat. Patent publication number CN110065618A discloses a multifunctional structural device for hypersonic vehicles and its operating method. This invention discloses a power supply module based on a thermoelectric conversion structure. By adding a heat protection module, a temperature control module, and a structural shell, a multifunctional structure for heat protection, temperature control, and power supply can be used in the complex aerodynamic and thermal environment of hypersonic vehicles. This invention's thermoelectric conversion structure for hypersonic vehicles is based on bulk thermoelectric materials. On the one hand, bulk thermoelectric materials are brittle, requiring additional load-bearing support structures, resulting in increased mass and size while lower efficiency. On the other hand, the larger mass and size affect the overall performance of the vehicle, thus limiting its application area to the compression surface of the vehicle, with a maximum installation area of ​​no more than 10 square meters. Summary of the Invention

[0003] The purpose of this invention is to solve the problems in the prior art and provide a thin-film thermoelectric structure for the inner wall of the skin of a hypersonic vehicle, which solves the problem that existing bulk thermoelectric materials require additional load-bearing support structures and have limited application areas.

[0004] To achieve the above objectives, the present invention employs the following technical solution:

[0005] A thin-film thermoelectric structure for the inner wall of a hypersonic vehicle skin includes an insulating heat-resistant layer, a thin-film thermoelectric layer, and a phase change temperature control layer connected in sequence.

[0006] The insulating and heat-resistant layer covers the inner wall of the hypersonic vehicle skin. The thermoelectric thin film layer contains a thermoelectric functional thin film group, which includes a conductive thin film layer and a base thin film layer. N-type and P-type thermoelectric thin film materials are alternately arranged on the base thin film layer to form a thermoelectric thin film layer. The conductive thin film layer is disposed on the thermoelectric thin film layer.

[0007] The conductive thin film layer contains conductive lines, and the substrate thin film layer is externally connected to a resistor. The conductive lines, the resistor, the N-type thin film thermoelectric material, and the P-type thin film thermoelectric material form a closed loop.

[0008] Furthermore, the thin-film thermoelectric layer includes a thermoelectric functional thin film assembly and an insulating matrix layer. The insulating matrix layer includes an upper insulating thin film layer and a lower insulating thin film layer. The thermoelectric functional thin film assembly is bonded between the upper insulating thin film layer and the lower insulating thin film layer by a high-temperature adhesive.

[0009] Furthermore, the insulating matrix layer is made of rigid or flexible aluminum nitride matrix with a thickness of 0.25 mm, and the upper insulating film layer and the lower insulating film layer are at different temperatures.

[0010] Furthermore, the thermoelectric functional thin film assembly also includes a heat-insulating film layer, the material of which is alumina fiber material.

[0011] Furthermore, the conductive thin film layer is disposed on a film layer composed of a thermoelectric thin film layer and a heat-insulating thin film layer.

[0012] Furthermore, the N-type thin-film thermoelectric material and the P-type thin-film thermoelectric material have the same external dimensions and a thickness of 50 to 1000 micrometers.

[0013] Furthermore, a gap is provided between the N-type thin-film thermoelectric material and the P-type thin-film thermoelectric material, and a heat-insulating film layer is provided at the gap position, the heat-insulating film layer being in a mesh shape.

[0014] Furthermore, silicon dioxide is disposed in the gap between the N-type thin-film thermoelectric material and the P-type thin-film thermoelectric material.

[0015] Furthermore, the insulating and heat-resistant layer is made of an antioxidant C / C composite material with a thickness of 1 to 2 mm, the thin film thermoelectric layer has a thickness of less than 1.26 mm, and the phase change temperature control layer has a thickness of 1 to 4 mm.

[0016] Furthermore, the conductive thin film layer is made of elemental silver and has a thickness of 0.25 mm, while the substrate thin film layer is made of single-crystal silicon.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] This invention provides a thin-film thermoelectric structure for the inner wall of a hypersonic vehicle skin. An insulating heat-resistant layer, a thin-film thermoelectric layer, and a phase-change temperature-control layer are sequentially disposed on the inner wall of the hypersonic vehicle skin. Utilizing the Seebeck effect of the thin-film thermoelectric material, the thin-film thermoelectric power generation structure converts out-of-plane heat flow into electromotive force. When an external resistor is connected to the substrate thin-film layer, a thermoelectric current is generated. The potentials are superimposed through a series arrangement of N-type and P-type thin-film thermoelectric materials, increasing both the thermoelectric electromotive force and the current. This invention integrates heat protection and thermal energy reuse, providing aerodynamic heat reuse structures and functions compared to traditional hypersonic vehicle designs, offering more ideas for the design of aircraft thermal protection systems. Compared to existing bulk thermoelectric materials, this invention offers several advantages: First, it is lightweight, with the thin-film module thickness at the micrometer and millimeter level, having virtually no impact on the overall size and mass of the hypersonic vehicle. Second, the thin-film material exhibits excellent ductility, allowing for a large layable area on the aircraft fuselage and wings, providing ample space for thin-film thermoelectric power generation. Third, this invention eliminates the need for additional load-bearing structures, simplifies assembly, and eliminates the need for mechanical connections, thus avoiding the unreliability inherent in mechanical structures. Fourth, the thin-film material fully utilizes its thermoelectric properties, preventing material waste and resulting in low material costs. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the distribution of the thin-film thermoelectric structure on the inner wall of the hypersonic vehicle skin of the present invention.

[0021] Figure 2 This is a schematic diagram of the thin-film thermoelectric structure of the inner wall of the hypersonic vehicle skin of the present invention.

[0022] Figure 3 This is a schematic diagram illustrating the structure and function of the thermoelectric functional thin film assembly of the present invention.

[0023] Figure 4 This is a schematic diagram of the thermoelectric functional thin film assembly of the present invention.

[0024] Among them: 1-Insulating heat protection layer, 2-Thin film thermoelectric layer, 3-Phase change temperature control layer, 4-Aircraft, 21-Insulating upper thin film layer, 22-Thermoelectric functional thin film group, 23-Insulating lower thin film layer, 201-Conductive thin film layer, 202-Heat insulation thin film layer, 203-Thermoelectric thin film layer, 204-Base film layer.

[0025] Figure 3 (a) is a schematic diagram of the thermoelectric thin film assembly under the influence of out-of-plane heat flow. Figure 3 (b) is a schematic diagram of the internal wiring connections of the thermoelectric functional thin film assembly. Figure 3 (c) is a schematic diagram of a closed loop formed by a thermoelectric functional thin film assembly. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0028] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0029] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0030] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0031] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0032] The present invention will now be described in further detail with reference to the accompanying drawings:

[0033] See Figures 1 to 4 This invention provides a thin-film thermoelectric structure for the inner wall of a hypersonic vehicle skin, comprising an insulating heat-resistant layer 1, a thin-film thermoelectric layer 2, and a phase change temperature control layer 3. The insulating heat-resistant layer 1 is formed by first spraying insulating heat-resistant material onto the inner wall of the hypersonic vehicle skin, and then curing it. The function of the insulating heat-resistant layer 1 is to block the large amount of aerodynamic heat generated during the cruise of the vehicle 4, ensuring that the thin-film thermoelectric layer operates normally within a reasonable temperature range. The thin-film thermoelectric layer 2 is connected to the bottom of the insulating heat-resistant layer 1 by a high-temperature adhesive. The thin-film thermoelectric layer 2 is a crucial functional structure for achieving thermoelectric conversion. The phase change temperature control layer 3 is connected to the bottom of the thin-film thermoelectric layer 2 by a high-temperature adhesive. The function of the phase change temperature control layer 3 is to increase the temperature difference, thereby improving the output efficiency and output capacity of the power generation.

[0034] like Figure 2 As shown, the thin-film thermoelectric layer 2 mainly includes a thermoelectric functional thin film group 22 and an insulating matrix layer. The thermoelectric functional thin film group 22 includes a conductive thin film layer 201, a heat-insulating thin film layer 202, a thermoelectric thin film layer 203, and a substrate thin film layer 204. The substrate thin film layer 204 is located at the bottom of the thermoelectric functional thin film group 22. The thermoelectric thin film layer 203 is attached to the substrate thin film layer 204 with gaps. The heat-insulating thin film layer 202 is in a mesh shape and is attached to the gaps formed by the thermoelectric thin film layer 203. The conductive thin film layer 201 is attached to the top of the film layer composed of the thermoelectric thin film layer 203 and the heat-insulating thin film layer 202. The insulating matrix layer includes an upper insulating film layer 21 and a lower insulating film layer 23. The thermoelectric functional film assembly 22 is connected between the upper insulating film layer 21 and the lower insulating film layer 23 by a high-temperature adhesive. The upper insulating film layer 21 and the lower insulating film layer 23 have different temperatures. The heat comes from the upper insulating film layer 21 and flows through the thermoelectric functional film assembly 22 to the lower insulating film layer 23.

[0035] like Figure 3As shown, the thermoelectric thin film layer 203 in the thermoelectric functional thin film assembly 22 is composed of alternating N-type and P-type thin film thermoelectric materials. Both N-type and P-type thin film thermoelectric materials are rectangular with identical dimensions and a thickness of 50–1000 micrometers. The N-type and P-type thin film thermoelectric materials are arranged alternately on the substrate thin film layer, with a certain gap between adjacent materials. During the flight of the hypersonic vehicle 4, the thermoelectric functional thin film assembly 22 generates a large amount of out-of-plane heat on the inner wall of the skin, resulting in a significant temperature gradient between the upper insulating matrix 21 and the lower insulating matrix 23. Due to the Seebeck effect of the thin film thermoelectric materials, a potential difference is generated between the top and bottom of the thermoelectric thin film layer 203 in an insulating environment. The conductive thin film layer 201 contains conductive circuits, and the substrate thin film layer 204 is externally connected to a resistor. Thus, the N-type and P-type thin film thermoelectric materials form a series circuit, creating a closed loop. N-type and P-type thin-film thermoelectric materials have different potentials under the same temperature difference due to their different materials. Connecting N-type and P-type thin-film thermoelectric materials in series achieves the effect of superimposed potentials, which increases the thermoelectric electromotive force and the current in the circuit. The positive direction of the current of the external resistor flows from the P-type thin-film thermoelectric material at the upper right end of the thin-film thermoelectric layer to the N-type thin-film thermoelectric material at the upper left end.

[0036] In a specific embodiment of the present invention, four pairs of thermoelectric thin film units are arranged laterally and eight pairs of thermoelectric thin film units are arranged longitudinally on the substrate thin film layer 204. The thermoelectric thin film units are composed of N-type thin film thermoelectric material on the left and P-type thin film thermoelectric material on the right.

[0037] like Figure 4 As shown, the individual structure of the thermoelectric functional thin film group 22 includes a conductive thin film layer 201, a heat insulation thin film layer 202, a thermoelectric thin film layer 203, a substrate thin film layer 204, and conductive lines. It is the basic unit for realizing thermoelectric conversion. The individual structures are connected into a whole through special arrangement to achieve the effect of superposition of thermoelectric electromotive force and enhance the output capability of thermoelectric conversion.

[0038] The insulating and heat-resistant layer 1 is made of an antioxidant C / C composite material with a thickness of 1–2 mm; the thin-film thermoelectric layer 2 has a thickness of less than 1.26 mm; and the phase-change temperature control layer 3 has a thickness of 1–4 mm. The upper insulating thin-film layer 21 and the lower insulating thin-film layer 23 are made of rigid or flexible aluminum nitride matrix (AlN) with a thickness of 0.25 mm. Aluminum nitride has good thermal conductivity and dielectric properties, is resistant to high-temperature impact, and has strong corrosion resistance. The conductive thin-film layer 201 is made of elemental silver with a thickness of 0.25 mm. Silver has good electrical conductivity and ductility. The heat-insulating thin-film layer 202 is made of alumina fiber material (Saffil Al-fiber), which has good heat insulation properties. The base thin-film layer 204 is made of monocrystalline silicon. Insulating silicon dioxide is sprayed into the gaps between the N-type and P-type thin-film thermoelectric materials within the thermoelectric thin-film unit to ensure circuit integrity.

[0039] The thin-film thermoelectric structure on the inner wall of the hypersonic vehicle skin of this invention, compared with the existing thermoelectric structure of bulk thermoelectric materials, adopts a design of multiple sets of thermoelectric thin films. On the one hand, the film is very lightweight, and the design of the film significantly reduces the structural mass. The thickness of the film module is on the millimeter level, which hardly adds any additional size to the hypersonic thermal protection system and does not affect the performance of the vehicle during cruise. The overall design of the hypersonic vehicle can almost disregard the impact of its structural mass and size. On the other hand, the film material has good ductility. Compared with the existing bulk thermoelectric power generation structure, the design of the film allows for a larger area to be laid on the inner wall of the fuselage and wing skin. The laying area of ​​the thin-film thermoelectric structure is more than 25 times that of the existing bulk thermoelectric power generation device, which has huge usable space.

[0040] The thin-film thermoelectric structure on the inner wall of the hypersonic vehicle skin of this invention, compared to existing thermoelectric structures made of bulk thermoelectric materials, does not require an additional load-bearing support structure. Furthermore, the assembly method of this invention is simple, eliminating the need for complex mechanical connection mechanisms, thus enhancing the reliability of the structure. When a thin-film module in the structure fails, only that module needs to be replaced, making maintenance and repair easy. The thin-film thermoelectric material fully utilizes the thermoelectric properties of the material, avoiding the waste caused by bulk materials, resulting in low cost and high utilization rate of thermoelectric materials.

[0041] The working principle of the thin-film thermoelectric structure on the inner wall of the hypersonic vehicle skin of the present invention:

[0042] This invention provides a thin-film thermoelectric structure for the inner wall of a hypersonic vehicle skin, which integrates heat protection and thermal energy reuse. It achieves thermoelectric power generation based on the Seebeck effect of thin-film thermoelectric materials, and improves the thermoelectric power generation capability and effect by connecting individual structures in series through a special arrangement.

[0043] During hypersonic cruise missions, the large surface area of ​​the aircraft's skin generates significant aerodynamic heat due to intense friction with the air. Most of this heat is dissipated into the air via radiation through the insulating skin, protecting the internal structure of the aircraft from heat damage. The remaining heat penetrates the skin and seeps into the thin-film thermoelectric layer 2. Within this layer, the heat transfer direction from top to bottom is: upper insulating thin film layer 21, conductive thin film layer 201, thermoelectric thin film layer 203, substrate thin film layer 204, and lower insulating thin film layer 23. The thermal insulation thin film layer 202 isolates the lateral conduction of heat flow to fully utilize the surface heat flow, ensuring approximately one-dimensional heat transfer. A temperature difference arises between the top and bottom of the thermoelectric thin film layer 203 due to heat conduction, generating a thermoelectric electromotive force due to the Seebeck effect of the thin-film thermoelectric material. Furthermore, this invention connects N-type and P-type thin-film thermoelectric materials in series, achieving a potential superposition effect and increasing the thermoelectric electromotive force. On the other hand, the phase change temperature control layer 3 placed at the bottom of the thin film thermoelectric layer 2 can improve the output efficiency and output capacity of power generation by controlling the temperature difference.

[0044] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A thin film thermoelectric structure for an inner wall surface of a hypersonic vehicle skin, characterized by, It includes an insulating heat-resistant layer (1), a thin film thermoelectric layer (2), and a phase change temperature control layer (3) connected in sequence. The insulating heat-resistant layer (1) covers the inner wall of the hypersonic vehicle skin. The thermoelectric thin film layer (2) is provided with a thermoelectric functional thin film group (22). The thermoelectric functional thin film group (22) includes a conductive thin film layer (201) and a substrate thin film layer (204). N-type thin film thermoelectric materials and P-type thin film thermoelectric materials are alternately arranged on the substrate thin film layer (204) to form a thermoelectric thin film layer (203). The conductive thin film layer (201) is disposed on the thermoelectric thin film layer (203). The conductive thin film layer (201) is provided with conductive lines, and the substrate thin film layer (204) is externally connected to a resistor. The conductive lines, the resistor, the N-type thin film thermoelectric material and the P-type thin film thermoelectric material form a closed loop. The thin film thermoelectric layer (2) includes a thermoelectric functional thin film group (22) and an insulating matrix layer. The insulating matrix layer includes an upper insulating thin film layer (21) and a lower insulating thin film layer (23). The thermoelectric functional thin film group (22) is connected between the upper insulating thin film layer (21) and the lower insulating thin film layer (23) by a high-temperature adhesive. The N-type thin-film thermoelectric material and the P-type thin-film thermoelectric material have the same external dimensions and a thickness of 50~1000 micrometers; The insulating and heat-resistant layer (1) is made of an antioxidant C / C composite material with a thickness of 1-2 mm. The thickness of the thin film thermoelectric layer (2) is less than 1.26 mm, and the thickness of the phase change temperature control layer (3) is 1-4 mm.

2. The thin-film thermoelectric structure of the inner wall of a hypersonic vehicle skin according to claim 1, characterized in that, The insulating matrix layer is made of rigid or flexible aluminum nitride matrix with a thickness of 0.25 mm. The upper insulating film layer (21) and the lower insulating film layer (23) have different temperatures.

3. The thin-film thermoelectric structure of the inner wall of a hypersonic vehicle skin according to claim 1, characterized in that, The thermoelectric functional thin film group (22) also includes a heat insulation film layer (202), the material of which is alumina fiber material.

4. The thin-film thermoelectric structure of the inner wall of a hypersonic vehicle skin according to claim 1, characterized in that, The conductive thin film layer (201) is disposed on a film layer composed of a thermoelectric thin film layer (203) and a heat insulation thin film layer (202).

5. The thin-film thermoelectric structure of the inner wall of a hypersonic vehicle skin according to claim 1, characterized in that, A gap is provided between the N-type thin film thermoelectric material and the P-type thin film thermoelectric material, and a heat insulation film layer (202) is provided at the gap position. The heat insulation film layer (202) is in the form of a grid.

6. The thin-film thermoelectric structure of the inner wall of a hypersonic vehicle skin according to claim 5, characterized in that, Silicon dioxide is disposed in the gap between the N-type thin-film thermoelectric material and the P-type thin-film thermoelectric material.

7. The thin-film thermoelectric structure of the inner wall of a hypersonic vehicle skin according to claim 1, characterized in that, The conductive thin film layer (201) is made of elemental silver and has a thickness of 0.25 mm, while the substrate thin film layer (204) is made of monocrystalline silicon.

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