Test piece and test device for evaluating heat insulation performance of low thermal conductivity material

Abstract

The application provides a test piece for evaluating the heat insulation performance of a low-thermal-conductivity material and a test device, the test piece comprising a test piece to be measured, a metal back plate and a heat insulation piece, wherein the test piece to be measured is made of a low-thermal-conductivity material; the metal back plate is fixedly arranged on the test piece to be measured, and the metal back plate comprises a first back plate unit, a second back plate unit and an Nth back plate unit from inside to outside in sequence, and there is no connection between any adjacent back plate units, and for any adjacent back plate units, the back plate unit located on the inside is arranged in the back plate unit located on the outside; the heat insulation piece is connected with the metal back plate, the metal back plate is arranged between the test piece to be measured and the heat insulation piece, the heat insulation piece has a concave cavity, and part of the back plate units are not in contact with the heat insulation piece. The application can better realize fine evaluation of the heat insulation performance of a low-thermal-conductivity material and ensure the evaluation precision.

Description

Technical Field

[0001] This invention relates to the field of thermal protection analysis technology, and in particular to a test specimen and test device for evaluating the thermal insulation performance of low thermal conductivity materials. Background Technology

[0002] Currently, low thermal conductivity insulation materials such as aerogels, thermal insulation felts, and ceramic tiles are widely used in aerospace fields such as thermal protection for high-speed aircraft, thermal control of airborne electronic equipment, and thermal control of spacecraft. Because these insulation materials are generally porous and radially translucent, their thermal conductivity is closely related to the heating method (including radiative heating, convection heating, and solid-state thermal conductivity) and the external air pressure environment. Data obtained from conventional thermal conductivity testing methods (generally solid-state thermal conductivity) cannot be directly used to predict the thermal insulation performance (generally radiative or convection heating) in ground and flight tests. Corrections must be made through tests simulating actual application conditions. Traditional test specimen structures and heat transfer methods, such as… Figure 1 As shown. However, since experiments simulating actual application conditions often involve three-dimensional effects and boundary effects, factors such as boundary heat leakage, heat absorption around the perimeter, and heat dissipation from the back can significantly affect the correction of the material's thermal conductivity, making it difficult to meet engineering requirements. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art.

[0004] Therefore, the present invention provides a test specimen and test device for evaluating the thermal insulation performance of low thermal conductivity materials.

[0005] The technical solution of the present invention is as follows:

[0006] According to one aspect, a test specimen for evaluating the thermal insulation performance of a low thermal conductivity material is provided, the test specimen comprising:

[0007] The test piece is made of a material with low thermal conductivity;

[0008] A metal backplate is fixedly mounted on the test piece. The metal backplate includes, from the inside out, a first backplate unit, a second backplate unit, ..., an Nth backplate unit, where N ≥ 2. There is no connection between any adjacent backplate units. For any adjacent backplate units: the backplate unit located on the inner side is located inside the backplate unit located on the outer side.

[0009] A heat insulation component is connected to a metal back plate, which is disposed between the test piece and the heat insulation component. The heat insulation component has a cavity, and a portion of the back plate unit does not contact the heat insulation component.

[0010] Furthermore, the outermost backplate unit of the metal backplate is connected to the heat insulation component, while the remaining backplate units are not in contact with the heat insulation component.

[0011] Furthermore, the number of backplane units is greater than or equal to 4.

[0012] Furthermore, the first backplate unit is a solid metal backplate, while the remaining backplate units are ring-shaped structures.

[0013] Furthermore, multiple backplane units are arranged concentrically.

[0014] Furthermore, all backplate units have the same thickness.

[0015] Furthermore, the emissivity of the inner surface of the cavity of the heat insulation component and the emissivity of the side of the metal back plate facing the heat insulation component shall not exceed 0.1.

[0016] Furthermore, the low thermal conductivity material includes aerogel, thermal insulation felt, or ceramic tile.

[0017] Furthermore, the heat insulation component is made of aerogel, heat insulation felt, or ceramic tile, and the heat insulation component is made of a different material than the test piece.

[0018] According to another aspect, a test apparatus for evaluating the thermal insulation performance of low thermal conductivity materials is provided. The test apparatus includes the aforementioned test specimen and a water-cooling fixture, wherein the test specimen is disposed within the water-cooling fixture.

[0019] The above technical solution divides the metal backplate of the test specimen into a first backplate unit, a second backplate unit, and so on, up to the Nth backplate unit, from the inside out. There is no connection between any adjacent backplate units (air separates them). For any adjacent backplate unit, the inner backplate unit is located within the outer backplate unit. This significantly reduces heat conduction from the metal backplate of the test specimen to the surroundings, bringing the test system closer to a one-dimensional thermal environment and enabling precise evaluation of the thermal insulation performance of low thermal conductivity materials. Simultaneously, the insulation component is designed with a cavity, preventing some backplate units from contacting the insulation component. This further reduces heat conduction and radiation from the metal backplate of the test specimen to the bottom insulation component, better enabling precise evaluation of the thermal insulation performance of low thermal conductivity materials and ensuring evaluation accuracy.

[0020] As can be seen, this invention provides a test specimen for evaluating the thermal insulation performance of thermal protection materials by constructing a near-one-dimensional heat transfer environment in a small space. It effectively eliminates three-dimensional and boundary effect interference in ground-based quartz lamp radiation heating tests, arc wind tunnel tests, and flight tests, accurately obtaining data on the material's thermal insulation performance. This invention has been applied to the evaluation test of thermal protection materials for a certain aircraft, reducing the temperature deviation of the metal backplate caused by heat leakage by 34% compared to traditional methods, significantly improving the accurate predictive ability of the thermal insulation performance of thermal protection materials. Attached Figure Description

[0021] The accompanying drawings, which form part of this specification, are provided to further illustrate embodiments of the invention and, together with the textual description, explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0022] Figure 1 A schematic diagram of the structure and heat transfer of a traditional test specimen is shown.

[0023] Figure 2 A schematic diagram of the structure of a test specimen for evaluating the thermal insulation performance of a low thermal conductivity material is shown according to a specific embodiment of the present invention;

[0024] Figure 3 A schematic diagram of the structure of a metal backplate provided according to a specific embodiment of the present invention is shown;

[0025] Figure 4 A schematic diagram of the structure of a heat insulation component provided according to a specific embodiment of the present invention is shown;

[0026] Figure 5 A schematic diagram of the installation of a traditional wind tunnel test specimen is shown;

[0027] Figure 6 A schematic diagram of the installation of the test piece according to a specific embodiment of the present invention is shown;

[0028] The above figures include the following reference numerals:

[0029] 10. Test piece; 20. Metal backplate; 21. First backplate unit; 22. Second backplate unit; 23. Third backplate unit; 24. Fourth backplate unit; 25. Fifth backplate unit; 30. Thermal insulation component; 30a. Cavity; 30b. Through hole; 40. Water-cooling fixture. Detailed Implementation

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. 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 a part of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0033] like Figure 2-4As shown, in one embodiment of the present invention, a test specimen for evaluating the thermal insulation performance of a low thermal conductivity material is provided. The test specimen includes a test piece 10, a metal back plate 20, and a thermal insulation component 30. The test piece 10 is made of a low thermal conductivity material. The metal back plate 20 is fixedly disposed on the test piece 10. The metal back plate 20 includes, from the inside to the outside, a first back plate unit 21, a second back plate unit 22, ..., an Nth back plate unit, where N≥2. There is no connection between any adjacent back plate units. For any adjacent back plate unit, the inner back plate unit is disposed within the outer back plate unit. The thermal insulation component 30 is connected to the metal back plate 20 and is disposed between the test piece 10 and the thermal insulation component 30. The thermal insulation component 30 has a cavity 30a, and some back plate units are not in contact with the thermal insulation component 30.

[0034] Those skilled in the art will know that low thermal conductivity materials generally refer to materials with a thermal conductivity of less than 0.05 W / m·K that can impede heat transfer, and are also known as thermal insulation materials.

[0035] In this embodiment of the invention, no connection between any adjacent backplate units means that there is no contact between them and there is air between them. Taking the first backplate unit 21 as a reference, the first backplate unit 21 is disposed in the second backplate unit 22, the second backplate unit 22 is disposed in the third backplate unit 23, the third backplate unit 23 is disposed in the fourth backplate unit 24, and so on. That is, for any adjacent backplate units: the backplate unit located on the inside is disposed in the backplate unit located on the outside.

[0036] In this embodiment of the invention, since the heat insulation member 30 has a cavity 30a, it is possible to prevent part of the back plate unit from contacting the heat insulation member 30.

[0037] By applying the above configuration, the metal backplate of the test specimen is sequentially divided into a first backplate unit, a second backplate unit, and so on, up to the Nth backplate unit, from the inside out. There is no connection between any adjacent backplate units (air separates them). For any adjacent backplate unit, the inner backplate unit is placed within the outer backplate unit. This significantly reduces heat conduction from the metal backplate of the test specimen to the surrounding areas, bringing the test system closer to a one-dimensional thermal environment and enabling more precise evaluation of the thermal insulation performance of low thermal conductivity materials. Simultaneously, the insulation component is designed with a cavity, preventing some backplate units from contacting the insulation component. This further reduces heat conduction and radiation from the metal backplate of the test specimen to the bottom insulation component, allowing for better precision evaluation of the thermal insulation performance of low thermal conductivity materials and ensuring evaluation accuracy.

[0038] As can be seen, the embodiments of the present invention provide a test specimen for evaluating the thermal insulation performance of thermal protection materials by constructing a near-one-dimensional heat transfer environment in a small space. It possesses the ability to effectively eliminate three-dimensional effects and boundary effects in ground-based quartz lamp radiation heating tests, arc wind tunnel tests, and flight tests, accurately obtaining data on the material's thermal insulation performance. This invention has been applied to the evaluation test of thermal protection materials for a certain aircraft, reducing the temperature deviation of the metal backplate caused by heat leakage by 34%, significantly improving the accurate predictive ability of the thermal insulation performance of thermal protection materials.

[0039] In the above embodiment, in order to better reduce the heat conduction from the test specimen to the insulation material, the outermost back plate unit of the metal back plate 20 is connected to the insulation component 30, and the remaining back plate units are not in contact with the insulation component 30.

[0040] That is, by designing the size of the cavity 30a, the heat insulation component 30 can be connected only to the outermost back plate unit, further reducing the contact area between the heat insulation component 30 and the metal back plate 20, thereby further reducing the heat conduction from the test specimen to the heat insulation component 30.

[0041] In the above embodiments, in order to further reduce the heat conduction from the center of the metal backplate to the surrounding area and control the heat dissipation to within 5%, the number of backplate units is greater than or equal to 4.

[0042] Preferably, the number of backplate units is greater than or equal to 5.

[0043] Preferably, the first backplate unit 21 is a solid metal backplate 20, and the remaining backplate units are annular structures. That is, the metal plate on the back of the test piece is designed as an annular structure, with no connection between each ring. This annular structure replaces the original metal material with air between each ring. The thermal conductivity of air is much lower than that of metal, thus greatly reducing the heat conduction from the center of the metal backplate 20 to the surrounding area.

[0044] In the above embodiments, in order to better ensure the accuracy of the assessment, multiple backplate units are arranged concentrically; the thickness of multiple backplate units is the same.

[0045] According to a specific embodiment of the present invention, such as Figure 3 As shown, the metal backplate 20 is a ring structure, including a first backplate unit 21, a second backplate unit 22, a third backplate unit 23, a fourth backplate unit 24, and a fifth backplate unit 25 arranged concentrically. The first backplate unit 21 is a solid metal backplate 20, and the second, third, fourth, and fifth backplate units are all ring structures with no connection between adjacent backplate units. The first backplate unit 21 is disposed within the second backplate unit 22, the second backplate unit 22 is disposed within the third backplate unit 23, the third backplate unit 23 is disposed within the fourth backplate unit 24, and the fourth backplate unit 24 is disposed within the fifth backplate unit 25.

[0046] In the above embodiments, in order to further reduce the radiative heat transfer between the heat insulation component and the metal back plate, the emissivity of the inner surface of the cavity 30a of the heat insulation component 30 and the side of the metal back plate 20 facing the heat insulation component 30 shall not exceed 0.1. This can be achieved by polishing, applying a film, galvanizing, etc., to reduce the radiative heat transfer between the heat insulation component 30 and the metal back plate 20.

[0047] In addition, for the convenience of temperature measurement, the cavity 30a of the heat insulation component 30 is also provided with a through hole 30b.

[0048] According to one embodiment of the present invention, the low thermal conductivity material includes aerogel, thermal insulation felt, or ceramic tile.

[0049] Preferably, the heat insulation element 30 is made of aerogel, heat insulation felt or ceramic tile, and the heat insulation element 30 is made of a different material than the test piece 10.

[0050] According to another embodiment of the present invention, a test apparatus for evaluating the thermal insulation performance of low thermal conductivity materials is also provided. The test apparatus includes the above-mentioned test specimen and a water-cooled fixture 40, wherein the test specimen is disposed within the water-cooled fixture 40.

[0051] like Figure 1 , 5 As shown, taking the electric arc wind tunnel test as an example, in order to improve the efficiency and accuracy of thermal conductivity identification, it is necessary to construct a quasi-one-dimensional heat transfer model for the thermal protection material under wind tunnel test conditions. However, the electric arc wind tunnel test uses high-temperature gas to convectively heat the test specimen, and the test fixtures around and at the bottom of the specimen are also heated simultaneously. Limited by the level of domestic testing facilities, to avoid the fixtures being burned due to excessive temperature, testing units have adopted a water-cooling scheme with protection on all four sides and heat insulation tiles on the bottom surface, such as... Figure 1 As shown, cooling water pipes are arranged inside the surrounding tooling, and a circulating water system is used to cool the tooling. Insulating tiles are placed in the cavity between the back of the test piece and the back tooling, providing support and insulation. The main problems with this design are as follows:

[0052] 1) The water-cooled fixture, with its four sides in direct contact with the test piece, rapidly conducts away the heat transferred from the thermal protection material to the metal backplate, exhibiting a significant three-dimensional effect that leads to a lower measured temperature of the metal backplate. Increasing the area of ​​the test piece would significantly increase the testing cost.

[0053] 2) The bottom heat insulation tile still has heat absorption capacity, absorbing the heat transferred from the heat protection material to the metal back plate, resulting in a lower measured temperature of the metal back plate.

[0054] The experimental specimen used in this invention can solve the two problems mentioned above in traditional electric arc wind tunnel testing schemes. It addresses the issues of reducing the influence of the water-cooled fixture 40 and the heat sink effect of the back insulation material by strictly controlling heat loss injected into the metal backplate 20 through methods such as blocking heat transfer paths and reducing back emissivity, thus constructing a near-one-dimensional thermally conductive environment. The specific structure is as follows: Figure 6 As shown.

[0055] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0056] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the 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 test apparatus for evaluating the thermal insulation performance of low thermal conductivity materials, characterized in that, The testing apparatus includes a water-cooled fixture and a test piece, the test piece being disposed within the water-cooled fixture, the test piece comprising: The test piece is made of a material with low thermal conductivity; A metal backplate, fixedly mounted on the test piece, comprises, from the inside out, a first backplate unit, a second backplate unit, ..., an Nth backplate unit. There is no connection between any two adjacent backplane units. For any two adjacent backplane units: the backplane unit located on the inner side is set inside the backplane unit located on the outer side. A heat insulation component is connected to a metal back plate, the metal back plate is disposed between the test piece and the heat insulation component, the heat insulation component has a cavity, and a portion of the back plate unit does not contact the heat insulation component; The outermost backplate unit of the metal backplate is connected to the heat insulation component, while the other backplate units are not in contact with the heat insulation component. The number of backplane units is greater than or equal to 4; The first backplate unit is a solid metal backplate, and the remaining backplate units are ring structures; Multiple backplate units are concentrically arranged; the thickness of the multiple backplate units is the same; the emissivity of the inner surface of the cavity of the heat insulation element and the side of the metal backplate facing the heat insulation element shall not exceed 0.

1. Among them, the heat loss injected into the metal backplate is strictly controlled by blocking the heat transfer path and reducing the back emissivity, thus constructing a near-one-dimensional thermal conduction environment.

2. The test apparatus for evaluating the thermal insulation performance of low thermal conductivity materials according to claim 1, characterized in that, The low thermal conductivity material includes aerogel, thermal insulation felt, or ceramic tile.

3. The test apparatus for evaluating the thermal insulation performance of low thermal conductivity materials according to claim 2, characterized in that, The insulation component is made of aerogel, insulation felt, or ceramic tile, and the insulation component is made of a different material than the test piece.

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