Measuring device and method for internal heat transfer of ablative material

Abstract

The invention discloses a device and a method for measuring internal heat transfer of an ablative material. The device comprises a flexible metal foil (1), a plurality of temperature sensors (2) arranged at intervals along the width direction of the metal foil (1), and an insulating layer (3) covering the metal foil (1) and the temperature sensors (2). The metal foil (1) is curled into a cylinder, a sensing point of the sensor (2) is located outside the cylinder, the cylinder is filled with the ablative material (4), and the whole body is embedded into a measuring hole of the ablative material body (5). The method comprises the steps of forming the measuring hole, arranging the sensor on the metal foil, performing insulation treatment, performing curl welding, filling the ablative material, performing embedded installation and the like. According to the invention, in-situ accurate measurement of longitudinal temperature distribution of the ablative layer is realized with minimum interference, and the problem of measurement of internal heat transfer of the ablative material is solved.

Description

Technical Field

[0001] This invention relates to the field of contact temperature measurement, and in particular to a measuring device and method for measuring heat transfer inside ablation materials. Background Technology

[0002] Ablation is a critical thermal protection method for high-speed aircraft, removing heat through chemical combustion or dust shedding to protect the structural strength of the aircraft. However, measuring the internal temperature field of ablation materials at high temperatures has always been a technical challenge. Traditional contact temperature sensors are difficult to deploy in ablation environments, while non-contact infrared thermography is easily interfered with by the smoke and dust generated during ablation.

[0003] Patent CN102901534A discloses a thin-film temperature ablation composite sensor, which fabricates a thin-film thermocouple on a ceramic substrate and embeds an insulating layer. Although this method can simultaneously measure temperature and ablation rate, the rigid ceramic substrate and the ablation material have significantly different mechanical and thermal properties. After embedding, the local thermal and stress fields are significantly altered, affecting the accuracy of the measurement.

[0004] Patent CN106871774A discloses a composite sensor that uses a core of heat-resistant material wound with fine thermocouple wire. Although this sensor can be ablated synchronously with the heat-resistant material, its measurement principle relies on the conductivity of the carbonized layer after ablation to measure the ablation thickness and temperature, which limits its ability to study the internal heat transfer law of the uncarbonized area during the ablation process.

[0005] Therefore, existing technologies lack an effective means to measure the longitudinal temperature distribution inside ablated materials in situ with minimal disturbance. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a device and method that has minimal impact on the original thermal field and can accurately measure the longitudinal temperature distribution inside the ablation material.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: On one hand, the present invention provides a measuring device for heat transfer inside an ablation material, comprising: Flexible metal foil; Multiple temperature sensors are arranged at intervals along the width direction of the metal foil; An insulating layer covers the metal foil and the temperature sensor, and exposes the sensing point of the temperature sensor; The metal foil is rolled into a cylindrical shape, so that the sensing point of the temperature sensor is located on the outer surface of the cylinder, and the inside of the cylinder is filled with ablative material. The measuring device is used to be embedded in the measuring hole of the ablative material body.

[0008] In one embodiment, the flexible metal foil is made of copper or a copper alloy.

[0009] In one embodiment, the temperature sensor is a thin-film thermocouple.

[0010] In one embodiment, the thin-film thermocouple is formed on the metal foil by sputtering or spot welding.

[0011] In one embodiment, the plurality of temperature sensors arranged along the width direction of the metal foil are distributed in an oblique or non-uniform manner.

[0012] In one embodiment, the insulating layer is a high-temperature resistant ceramic insulating layer formed by a thermal spraying process.

[0013] On the other hand, the present invention also provides a method for measuring heat transfer inside an ablation material, comprising the following steps: A measuring hole is made in the ablation material body; A flexible metal foil is provided, and the number and spacing of measuring points are determined according to the heat transfer path. Multiple temperature sensors are arranged along the width direction of the metal foil according to the number and spacing of measuring points. An insulating layer is formed on the metal foil and the temperature sensor, and the sensing point of the temperature sensor is exposed; The metal foil is rolled into a cylinder that matches the measuring hole, and the seam is welded. The interior of the cylinder is filled with an ablative material; The filled cylindrical device is then inserted into the measuring hole.

[0014] In one embodiment, the process of forming the insulating layer specifically includes: Before arranging the temperature sensor, a temporary protective layer is used to cover the pre-defined temperature sensor arrangement area on the metal foil; A first insulating layer is formed in the area where the metal foil does not cover the temporary protective layer; Remove the temporary protective layer and arrange the temperature sensor on the exposed temperature sensor arrangement area; A second insulating layer is formed on the temperature sensor to cover it.

[0015] In one embodiment, the temperature sensor's sensing point faces outwards when the metal foil is rolled up.

[0016] In one embodiment, the number and spacing of the temperature sensors are determined based on an analysis of the ablation layer thickness and the expected temperature gradient.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects: This invention uses flexible, high thermal conductivity metal foil as the temperature sensor carrier and heat transfer path, avoiding the thermal barrier effect caused by low thermal conductivity or rigid substrates, minimizing interference with the test thermal field, and resulting in more accurate measurement results.

[0018] This invention involves directly embedding a cylindrical metal foil into the ablation material, allowing for direct measurement of the temperature at a specified depth within the ablation layer. The data is direct and reliable, making it suitable for studying heat transfer mechanisms. The cylindrical structure formed from the flexible metal foil causes minimal damage to the strength of the ablation material and offers better structural compatibility. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic cross-sectional view of the measuring device after it has been embedded with ablation material, according to an embodiment of the present invention. Figure 2 This is a schematic diagram showing the distribution of temperature sensors along the depth of the ablation material in an embodiment of the present invention; Figure 3 This is a schematic diagram of the unfolded state of the metal foil carrier in an embodiment of the present invention.

[0021] Among them, 1-metal foil, 2-temperature sensor, 3-insulating layer, 4-ablation material, 5-ablation material body, 10-temperature sensor arrangement area, and 11-welding area. Detailed Implementation

[0022] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0023] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0024] This invention provides a measuring device and method for measuring heat transfer inside ablation materials.

[0025] like Figure 1 As shown, the core of the measuring device provided in this embodiment of the invention is a cylindrical structure embedded in the ablation material body 5 after installation. The structure consists of, from the inside out: the filled ablation material 4, the flexible metal foil 1, and the insulating layer 3. Multiple temperature sensors (thermocouples) 2 are arranged at intervals along the width direction of the metal foil (i.e., the depth direction of the ablation layer / the axial direction of the cylinder), and their sensing points penetrate the insulating layer 3 and directly contact the surrounding ablation material body 5.

[0026] The preparation of the measuring device and the measuring method are described below.

[0027] First, measurement holes are made on the ablation material body 5. The location and number of measurement holes can be determined according to the experimental requirements. The hole diameter needs to be evaluated through structural mechanics simulation to ensure that it does not significantly weaken the overall strength of the ablation material body 5. For example, if the structural strength allows, as the thickness of the ablation layer increases, the number of temperature sensor placement points also needs to be increased, and the relative hole diameter also needs to be increased.

[0028] Prepare a flexible metal foil 1, exemplarily with a thickness of 0.5 mm. The number of flexible metal foils can be determined according to the temperature range to be measured. This embodiment of the invention uses one flexible metal foil for illustration. The width W of the metal foil is the same as the thickness of the ablation layer to be measured, and its length L is slightly larger than the circumference of the aforementioned measuring hole. This embodiment of the invention preferably uses copper or a copper alloy with high thermal conductivity as the metal foil material. Because copper's extremely high thermal conductivity allows it to quickly reach thermal equilibrium with the surrounding ablation material after embedding, it avoids the formation of a "thermal barrier" due to the poor thermal conductivity of the carrier material, thereby minimizing interference with the original ablation thermal field and ensuring more accurate measured temperature data.

[0029] The measuring device provided in this embodiment of the invention aims to obtain a representative longitudinal temperature distribution, thus requiring the planning of measuring points. After providing the metal foil 1, the number and spacing of measuring points are determined according to the heat transfer path.

[0030] Specifically: First, thermal simulation is performed on the ablation material body 5 to be tested, simulating its internal temperature field under the expected thermal load. By analyzing the temperature gradient distribution in the simulation results, denser measuring points can be set in areas with drastic gradient changes, and sparser measuring points in areas with gentle gradient changes. The determination of the number of measuring points needs to comprehensively consider the ablation layer thickness (H), the sensor size itself, and the allowable range of the opening for structural strength. A feasible estimation method is to let the total number of measuring points N≈H / Δh, where Δh is a representative measurement spacing determined based on simulation and experience, for example, 3-5mm. Finally, based on the determined number (N) and the non-uniformly distributed interval, the specific placement position of each temperature sensor 2 is determined in the width direction of the metal foil 1. Through this pre-design based on the heat transfer mechanism, the most critical temperature field information inside the ablation layer can be captured efficiently and accurately with a minimum number of sensors, avoiding the waste of measurement resources or the omission of key data, thereby providing experimental data with maximum value for the design and verification of the thermal protection system.

[0031] The above-described theoretical analysis or heat transfer simulation analysis of the ablation layer thickness and expected temperature gradient determined the number and spacing of temperature sensors 2 required along the width direction of the metal foil 1 (i.e., the depth direction of the ablation layer), ensuring that multiple temperature sensors 2 are spaced apart along the width direction of the metal foil 1. In this embodiment, the temperature sensors 2 are preferably thin-film thermocouples, such as K-type or S-type. These thin-film thermocouples are formed on the surface of the metal foil 1 by sputtering or micro-spot welding. The advantage of using thin-film technology is that its thickness is extremely thin (micrometer level), greatly reducing the additional volume, avoiding changes in the local heat flow path due to excessive sensor thickness, and ensuring minimal impact on the thermal field. The distribution of multiple thin-film thermocouples can be either oblique or non-uniform along the width direction of the metal foil 1. Using an oblique or non-uniform distribution allows for the arrangement of denser measurement points in areas of rapid temperature change and sparser measurement points in areas of gradual change, based on the expected changes in the thermal gradient. This allows for the acquisition of the most representative temperature field information with the fewest number of sensors, optimizing measurement efficiency and cost.

[0032] like Figure 2 As shown, this embodiment of the invention distributes multiple temperature sensors 2 along the longitudinal direction (i.e., the thickness direction or the thermal protection direction) of the ablation material to measure the internal temperature gradient. These temperature sensors are integrated into the aforementioned measuring device. When the device is embedded in the ablation material body, each temperature sensor is located at a different depth, enabling synchronous and in-situ acquisition of longitudinal temperature field data from the heated surface to the internal structural components. This distribution directly corresponds to the heat transfer path during the ablation process, allowing the measurement data to accurately reflect the process of heat penetration into the material's interior. This provides crucial experimental evidence for evaluating the effectiveness of the thermal protection system and verifying the heat transfer model.

[0033] In this embodiment of the invention, insulation protection is required for the non-measuring area of ​​the metal foil. First, after determining the measuring point location and before placing the temperature sensor 2, high-temperature resistant tape (such as polyimide tape) is used as a temporary protective layer to precisely cover the pre-set temperature sensor placement area 10 (approximately 5mm × 5mm) on the metal foil 1. Figure 3 As shown. By setting up a temporary protective layer to reserve space for subsequent temperature sensors, it is ensured that this area will not be covered during the subsequent overall insulation process.

[0034] Next, for the areas on the metal foil 1 not covered by the temporary protective layer, a high-temperature resistant ceramic insulating layer 3 is evenly laid using a thermal spraying process such as plasma spraying or flame spraying, forming the first insulating layer covering the metal foil substrate. For example, the high-temperature resistant insulating layer 3 is made of alumina or zirconium oxide, etc. This completes the insulation protection of the sensor circuit wires and establishes a basic protective layer.

[0035] Then, the temporary protective layer is removed, revealing a clean, pre-defined temperature sensor arrangement area 10 on the surface of the metal foil, uncovered by any insulating material. Subsequently, temperature sensors 2 (such as thin-film thermocouples) are arranged on these precisely exposed temperature sensor arrangement areas 10 using sputtering or spot welding processes. This method ensures that the sensing point of the temperature sensor 2 can directly and fully contact the ablation material without any intermediate insulating layer, thereby achieving rapid temperature measurement response and high accuracy.

[0036] Finally, a thin layer of insulating material is laid on the surface of the temperature sensor 2 (excluding the sensing point), forming a second insulating layer, exposing the sensing point of the temperature sensor 2. This second insulating layer protects the fragile temperature sensor wire from physical damage during installation and carbonization in the ablation environment, improving the durability and reliability of the temperature sensor. The insulating layer 3 prevents electrical short circuits between the metal foil 1 and the ablation material body 5, protecting the thin-film thermocouple from chemical corrosion and particle erosion in harsh ablation environments. Furthermore, the ceramic material itself has good high-temperature resistance and a certain degree of thermal insulation, protecting the internal structure.

[0037] like Figure 3As shown, after insulation treatment, the measuring device is finally assembled. The metal foil 1 is rolled along its length with the side containing the temperature sensor 2 and the insulating layer 3 facing outwards, so that the welding areas 11 are joined together to form a cylindrical shape matching the measuring aperture, ensuring the sensing point of the temperature sensor 2 is located on the outer surface of the cylinder. Positioning the sensing point outwards ensures that all sensing points of the temperature sensor 2 can directly face and closely contact the ablation material body 5, enabling accurate in-situ measurement. After rolling, the welding areas 11 of the metal foil 1 are sealed using laser welding, forming a robust and complete cylindrical shell.

[0038] Then, the internal cavity of the cylindrical structure is filled with ablation material 4, so that the material composition of the entire insert is as consistent as possible with the ablation material body 5. This ensures that the ablation rate and thermophysical property changes of the insert and the body are highly synchronized during the ablation process, avoiding abrupt changes in the ablation profile and thermal field distortion caused by excessive differences in the material properties of the insert and the body, and reducing interference with the experimental thermal field.

[0039] Finally, the filled cylindrical measuring device is inserted into the pre-drilled measuring hole on the ablation material body 5 to complete the installation.

[0040] During ablation tests (such as wind tunnel tests), the surface of the ablated material begins to ablate and recede. Because the device of this invention ablates synchronously with the surrounding material, multiple thin-film thermocouples inside it will sequentially and in situ measure the actual temperature at different depths within the ablated layer as ablation progresses. All temperature data are transmitted to a data acquisition system via lead-out compensation wires, thereby obtaining the corresponding longitudinal temperature distribution curve within the ablated material, providing accurate data for evaluating the performance of the thermal protection system.

[0041] The embodiments of the present invention achieve high-fidelity, low-interference, multi-point in-situ measurement of the heat transfer process inside the ablation material through the synergistic design of a flexible high thermal conductivity metal foil carrier, a thin-film and optimized distribution temperature sensor, a reliable insulation protection process, and an internally filled synchronous ablation material, effectively solving the long-standing technical bottleneck.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the embodiments of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A measuring device for heat transfer inside an ablation material, characterized in that, include: Flexible metal foil (1); Multiple temperature sensors (2) are arranged at intervals along the width direction of the metal foil (1); An insulating layer (3) is applied to the metal foil (1) and the temperature sensor (2), and the sensing point of the temperature sensor (2) is exposed. The metal foil (1) is rolled into a cylindrical shape, so that the sensing point of the temperature sensor (2) is located on the outer surface of the cylinder, and the cylinder is filled with ablative material (4). The measuring device is used to be embedded in the measuring hole of the ablative material body (5).

2. The measuring device according to claim 1, characterized in that, The flexible metal foil (1) is made of copper or a copper alloy.

3. The measuring device according to claim 1, characterized in that, The temperature sensor (2) is a thin-film thermocouple.

4. The measuring device according to claim 3, characterized in that, The thin-film thermocouple is formed on the metal foil (1) by sputtering or spot welding.

5. The measuring device according to claim 1, characterized in that, The multiple temperature sensors (2) arranged along the width direction of the metal foil (1) are distributed in an oblique or non-uniform manner.

6. The measuring device according to claim 1, characterized in that, The insulating layer (3) is a high-temperature resistant ceramic insulating layer formed by thermal spraying process.

7. A method for measuring internal heat transfer in an ablation material, characterized in that, Includes the following steps: A measuring hole is made on the ablation material body (5); A flexible metal foil (1) is provided, the number and spacing of measuring points are determined according to the heat transfer path, and multiple temperature sensors (2) are arranged along the width direction of the metal foil (1) according to the number and spacing of measuring points. An insulating layer (3) is formed on the metal foil (1) and the temperature sensor (2), and the sensing point of the temperature sensor (2) is exposed; The metal foil (1) is rolled into a cylinder that matches the measuring hole, and the welding area (11) is welded. The inside of the cylinder is filled with ablative material (4); The filled cylindrical device is then inserted into the measuring hole.

8. The method according to claim 7, characterized in that, The process of forming the insulating layer (3) specifically includes: Before arranging the temperature sensor (2), a temporary protective layer is used to cover the pre-set temperature sensor arrangement area (10) on the metal foil (1). A first insulating layer is formed in the area where the metal foil (1) does not cover the temporary protective layer; Remove the temporary protective layer and place the temperature sensor (2) on the exposed temperature sensor arrangement area (10). A second insulating layer is formed on the temperature sensor (2) to cover the temperature sensor.

9. The method according to claim 7, characterized in that, When the metal foil (1) is rolled up, the sensing point of the temperature sensor (2) faces outward.

10. The method according to claim 7, characterized in that, The number and distribution interval of the temperature sensors (2) are determined based on the analysis of the ablation layer thickness and the expected temperature gradient.

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