In-situ X-ray tomography device of plasma wind tunnel

Abstract

The invention discloses an in-situ X-ray tomography scanning device for a plasma wind tunnel, and belongs to the technical field of scanning devices.The in-situ X-ray tomography scanning device comprises a plasma wind tunnel test cabin, a first electric displacement sliding rail is installed at the bottom of the inner side of the plasma wind tunnel test cabin, and a rotating mechanism is installed on the first electric displacement sliding rail and comprises a rotating motor; a sample clamp is installed at the front end of the rotating motor, an external thermal protection shell is arranged on the outer side of the rotating motor, the lower portion of the external thermal protection shell is connected with a sample support, and the sample support is fixedly installed on a first electric displacement sliding rail. According to the in-situ X-ray tomography scanning device of the plasma wind tunnel, after the plasma wind tunnel is started, a high-enthalpy airflow environment is generated in the plasma wind tunnel test cabin, the thermal protection material stagnation point test model is moved to a test area, the test model is rotated by the rotating structure, and the thermal protection material stagnation point test is completed. An X-ray detection system is combined with an X-ray tomography imaging technology to realize in-situ characterization of three-dimensional microstructure information of a test sample.

Description

Technical Field

[0001] This invention relates to the field of scanning device technology, and in particular to an in-situ X-ray tomography scanning device for a plasma wind tunnel. Background Technology

[0002] Current wind tunnel tests mainly rely on surface temperature measurement (such as infrared thermal imagers) and morphological observation, lacking the ability to monitor the in-situ evolution of the material's internal microstructure in real time. Key information such as changes in subsurface porosity, crack propagation paths, and interface failure mechanisms during ablation is difficult to capture, hindering the optimal design of thermal protection materials.

[0003] In-situ X-ray computed tomography (XCT) is an ideal method for revealing the internal damage mechanisms of materials due to its high penetration and three-dimensional microstructure imaging capabilities. While traditional XCT technology is maturely applied in ambient temperature environments, its use in the extreme environments of plasma wind tunnels has not yet been reported. Currently, there is a lack of methods for in-situ research on the internal structure of materials in wind tunnel environments, necessitating the development of related technologies. Summary of the Invention

[0004] The purpose of this invention is to provide an in-situ X-ray tomography device for a plasma wind tunnel. After the plasma wind tunnel is started, a high-temperature gas flow is generated by a high-frequency plasma generator and accelerated by a nozzle to create a high-enthalpy gas flow environment in the plasma wind tunnel test chamber. The rotating mechanism and the thermal protection material stagnation test model are moved to the test area by a first electric displacement slide rail. The rotating structure rotates the test model, and the X-ray detection system combined with X-ray tomography imaging technology is used to achieve in-situ characterization of the three-dimensional microstructure information of the test sample.

[0005] To achieve the above objectives, the present invention provides an in-situ X-ray tomography device for a plasma wind tunnel, comprising a plasma wind tunnel test chamber, a first electrically driven displacement slide rail installed on the bottom inner side of the plasma wind tunnel test chamber, a rotating mechanism installed on the first electrically driven displacement slide rail, the rotating mechanism comprising a rotating motor, a sample clamp installed at the front end of the rotating motor, an external thermal protection shell provided on the outside of the rotating motor, and a sample holder connected to the bottom of the external thermal protection shell, the sample holder being fixedly installed on the first electrically driven displacement slide rail.

[0006] Preferably, the outer thermal protection shell is equipped with a copper tube water cooling jacket inside, and the outer thermal protection shell has a first water inlet and a first water outlet for the cooling circuit on one side.

[0007] Preferably, a second water inlet for the sample holder cooling circuit is provided on one side of the bottom of the sample holder, and a second water outlet for the sample holder cooling circuit is provided on the sample holder opposite the second water inlet.

[0008] Preferably, the plasma wind tunnel test chamber is equipped with a double-layer water-cooled sandwich structure, and a third water inlet and a third water outlet are provided on one side of the bottom of the plasma wind tunnel test chamber. An infrared temperature measurement system and a binocular vision imaging system are installed on its top.

[0009] Preferably, the sample fixture holds a heat protection material stagnation test model, which is a spherical cone structure with a ball head.

[0010] Preferably, an X-ray detection system is installed on one side of the plasma wind tunnel test chamber. The X-ray detection system is mounted on the second electrically driven displacement slide rail and consists of an X-ray source and a flat panel detector.

[0011] Therefore, this invention employs an in-situ X-ray tomography device for a plasma wind tunnel, which, in terms of extreme environment adaptability, ensures long-term stable operation of the X-ray detection system and high-precision rotating mechanism under high temperature and high enthalpy environments through a multi-loop water-cooling system design and high-temperature protection measures. Multimodal data fusion acquisition, simultaneously integrating X-ray tomography, infrared thermography, and visual imaging, provides diagnostic capabilities from the material surface to its interior. This multi-dimensional data acquisition method can obtain the temperature field and morphological changes of the material surface, revealing the dynamic evolution process of the internal microstructure. It fills the gap in in-situ characterization methods for the interior of materials in a plasma wind tunnel environment, providing technical means for the optimized design and performance evaluation of thermal protection materials. By obtaining internal damage evolution data of materials under realistic simulation environments, it shortens the R&D cycle of new thermal protection materials, reduces R&D costs, and provides data support for the development of thermal protection materials.

[0012] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0013] Figure 1 This is a three-dimensional structural schematic diagram of an in-situ X-ray tomography device for a plasma wind tunnel according to the present invention. Figure 2 This is a three-dimensional structural schematic diagram of the rotating mechanism of an in-situ X-ray tomography device for a plasma wind tunnel according to the present invention.

[0014] Figure Labels 1. Plasma wind tunnel test chamber; 2. Rotation mechanism; 3. Thermal protection material stagnation test model; 4. First electric displacement slide rail; 5. X-ray detection system; 6. Binocular vision imaging system; 7. Infrared temperature measurement system; 8. Third water inlet; 9. Third water outlet; 10. External thermal protection shell; 11. First water inlet; 12. First water outlet; 13. Sample holder; 14. Second water inlet; 15. Second water outlet. Detailed Implementation

[0015] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0016] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0017] Example 1 like Figures 1 to 2 As shown, this invention provides an in-situ X-ray tomography device for a plasma wind tunnel, including a plasma wind tunnel test chamber 1. The plasma wind tunnel test chamber 1 employs a high-frequency inductive plasma generator (operating frequency 450~600kHz). Inert gas (such as argon or nitrogen) is injected through a vortex-type air intake device. The induction coil is a specially designed water-cooled copper coil tightly wound around the outer surface of a high-purity quartz tube, forming an alternating electromagnetic field. The inert gas is ohmically heated to ultra-high temperatures (exceeding 5000K) and then mixed with the test gas, ionizing to form a high-enthalpy plasma jet. The nozzle accelerates the jet to supersonic speeds (Ma). 2) Simulate the multi-field coupling environment when entering the atmosphere.

[0018] A first electrically driven displacement slide rail 4 is installed at the bottom inner side of the plasma wind tunnel test chamber 1. A rotating mechanism 2 is mounted on the first electrically driven displacement slide rail 4. The first electrically driven displacement slide rail 4 is a high-precision electrically driven slide rail, which can drive the rotating mechanism 2 to move. The spatial position of the sample is precisely controlled by a host computer to achieve calibration with the detection point of the X-ray detection system 5. The rotating mechanism 2 includes a rotary motor, which adopts a high-precision servo motor drive system to move the sample... Continuous rotation, achieving a high degree of precision. The rotational speed can be steplessly adjusted within the range of 0.5-10 rpm. The rotating mechanism 2 also integrates a high-precision photoelectric encoder to provide real-time feedback on rotational position information, ensuring accurate angle control. A sample clamp is installed at the front end of the rotating motor. The sample clamp is made of high-temperature alloy material and can firmly fix test samples of various sizes of thermal protection materials. An external thermal protection shell 10 is set on the outside of the rotating motor. The external thermal protection shell 10 has a copper tube water cooling jacket inside. The first water inlet 11 and the first water outlet 12 of the cooling circuit of the external thermal protection shell 10 are set on one side, and deionized water is used for circulating cooling (temperature controlled at...). This ensures stable operation during long-term testing in high-enthalpy environments.

[0019] The outer thermal protection shell 10 is connected to the sample holder 13 at the bottom. The sample holder 13 is fixedly mounted on the first electric displacement slide rail 4. The sample holder 13 provides support for the rotary motor. The first electric displacement slide rail 4 moves the sample holder 13, thereby moving the rotary motor and the thermal protection material stationary test model 3. A second water inlet 14 for the cooling circuit of the sample holder 13 is provided on one side of the bottom of the sample holder 13. A second water outlet 15 for the cooling circuit of the sample holder 13 is provided on the sample holder 13 opposite to the second water inlet 14, facilitating the cooling circulation of deionized water.

[0020] The plasma wind tunnel test chamber 1 is equipped with a double-layer water-cooled sandwich structure, and uses a deionized water circulation system (temperature) 30 To prevent high-temperature overflow and ensure long-term stable operation of the equipment, the maximum testing time can reach 3000s. The plasma wind tunnel test chamber 1 has a third water inlet 8 and a third water outlet 9 on one side of its bottom. An infrared temperature measurement system 7 and a binocular vision imaging system 6 are installed on the top of the plasma wind tunnel test chamber 1. The binocular vision imaging system 6 and the infrared temperature measurement system 7 are mainly implemented by two industrial cameras and one infrared radiation imaging camera. Before each test, the binocular vision imaging system 6 is calibrated with a standard calibration plate to obtain spatial information and performs in-situ detection of the external morphology of the thermally protected sample during the experiment. The infrared temperature measurement system 7 uses infrared radiation emitted by the thermally protected material to perform in-situ detection of the temperature field, enabling real-time acquisition of the temperature field distribution and morphological change data on the model surface.

[0021] The sample fixture holds a thermal protection material stagnation test model 3, which is usually made of advanced thermal protection materials such as carbon fiber reinforced composite materials. It is a ball-cone structure with a ball head and focuses on the ablation resistance of the stagnation point, which can truly reflect the response characteristics of the material in extreme environments.

[0022] An X-ray detection system 5 is installed on one side of the plasma wind tunnel test chamber 1. The X-ray detection system 5 is mounted on a second electrically driven displacement slide rail and consists of an X-ray source and a flat-panel detector. The X-ray source employs a high-stability design, capable of emitting high-energy X-rays that penetrate the test sample. The second electrically driven displacement slide rail is an electrically precise displacement device that can accurately adjust the receiving position to obtain optimal signal quality. During data acquisition, the X-ray detection system 5... After acquiring a single projection image and a total of 360 images, the sample's three-dimensional reconstruction is completed using an X-ray computed tomography (CT) imaging algorithm, achieving a spatial resolution of up to [missing information]. 10 m.

[0023] The specific steps for using the in-situ X-ray tomography device for a plasma wind tunnel provided by this invention are as follows: For sample installation and calibration, the first step is to select the thermal protection material to be tested, such as commonly used carbon fiber reinforced composite material, and fabricate a standard-sized spherical cone-shaped stagnation point test model (typically with a diameter of 10 mm). The prepared test model is then mounted on the sample clamp of the rotating mechanism 2, ensuring that the sample axis is strictly aligned with the servo motor's rotation axis. Subsequently, the spatial position of the sample is finely adjusted using the first electric displacement slide rail 4 system, completing the precise calibration of the X-ray source, sample, and flat-panel detector. A laser positioning assistance system is used during this process to ensure alignment accuracy.

[0024] The plasma wind tunnel parameters were adjusted by starting the high-frequency plasma generator and regulating the inlet parameters via a gas flow controller, gradually increasing the generator power to the range of 50-300kW to generate the high-enthalpy plasma jet to be tested. The system can simulate experimental conditions including: enthalpy range of 1~20 MJ / kg; maximum heat flux density up to 4 MW / m³. 2 (For 10mm diameter samples); the maximum stagnation pressure is 10kPa. These parameters can be precisely adjusted according to specific test requirements to simulate different reentry environments.

[0025] The cooling system is activated before wind tunnel operation to ensure the cooling water temperature is consistently maintained at 30°C. The following describes the system's independent cooling of key components such as the plasma test chamber and the servo motor of the rotating mechanism 2, preventing performance degradation or damage due to high temperatures. It primarily comprises three cooling loops: the first loop is dedicated to cooling the plasma wind tunnel test chamber 1, with its water-cooled jacket integrated into the inner wall of the chamber, forming a surrounding flow channel. The third inlet 8 and the third outlet 9 are located on the lower side of the chamber for convective heat exchange. The second loop targets the servo motor of the rotating mechanism 2, employing a double-layer spiral copper tube water-cooled jacket to tightly enclose the motor housing, and using a high thermal conductivity interface material to ensure efficient heat conduction. The third loop provides thermal protection for the sample holder 13, which features a single-channel flow loop design to prevent structural damage to the exposed areas of the sample holder 13 due to high temperatures. All loops are supplied by a central deionized water storage tank, with flow rates regulated by multiple independently controlled variable frequency centrifugal pumps, and heat exchange via plate heat exchangers. The system is equipped with high-precision temperature sensors to monitor the loop water temperature in real time, feeding back to the control system to ensure the cooling water temperature is maintained stably at a certain level. The set range ensures the long-term operational stability of the device under high temperature and high enthalpy environments.

[0026] Data acquisition and monitoring: During the model ablation process (e.g., lasting 1000 seconds), the rotating mechanism 2 drives the sample to rotate continuously at a predetermined speed, and the X-ray system rotates at a speed of... The frequency of acquiring a projection image varies depending on the density of the material, and the exposure time for each image also differs. The system acquires 720 complete X-ray projection images within its range. To achieve simultaneous multimodal data acquisition, this invention integrates a binocular vision imaging system 6 and an infrared temperature measurement system 7. The binocular vision imaging system 6 consists of two high-resolution industrial CCD cameras rigidly mounted on an adjustable platform, which is fixed to the observation window above the plasma test chamber via a bracket. The infrared temperature measurement system 7 uses a mid-wave infrared thermal imager, mounted on a fixed platform at the top of the test chamber. An infrared window is added to the top of the test chamber to ensure monitoring of the model's surface temperature field. Both systems are installed in locations that avoid the X-ray path and are synchronized with the X-ray tomography system via a unified triggering system.

[0027] Three-dimensional reconstruction and data analysis: After the experiment, the acquired projection image sequence was processed using an X-ray tomography reconstruction algorithm to generate a time-resolution three-dimensional microstructure evolution sequence of the sample. Using specialized image processing and analysis software, key parameters such as porosity changes, crack propagation rates, and interface delamination within the material can be quantitatively extracted, revealing the damage evolution mechanism of the material under extreme environments.

[0028] Application examples 1) First, select carbon fiber reinforced composite materials (C) commonly used for thermal protection. C or C SiC) fabrication dimensions are A 10mm spherical cone-shaped stagnation point test model. The sample preparation process includes precision machining and surface cleaning to ensure a surface roughness Ra. 3 m. During installation, laser alignment is used to ensure the coaxiality error between the sample axis and the servo motor axis; 2) The plasma wind tunnel used can simulate enthalpy values ​​ranging from 1 to 20 MJ. kg continuously adjustable, maximum heat flux density 4MW m 2 (against (10mm sample), maximum stagnation point pressure 10kPa. During startup, the gas flow control adjusts the inlet flow rate, gradually increasing the power of the high-frequency plasma generator from 0 to 50-300kW to ensure the generation of a stable high-enthalpy plasma jet. The cooling system, as the core of ensuring stable operation of the device in extreme environments, adopts a multi-loop independent design. Specifically, the system includes three main cooling loops: the first loop is dedicated to cooling the plasma wind tunnel test chamber 1, with its water-cooled jacket integrated into the inner wall of the test chamber, forming a surrounding flow channel. The third water inlet 8 and the third water outlet 9 are located on the lower side of the chamber for convective heat transfer. The second loop is for the servo motor of the rotating mechanism 2, using a double-layer spiral copper tube water-cooled jacket to tightly wrap the motor housing, and using a high thermal conductivity interface material to ensure efficient heat conduction. The third loop provides thermal protection for the sample holder 13. The sample holder 13 adopts a single-channel flow channel design inside, mainly to prevent the part of the sample holder 13 exposed to the heat flow area from structural damage due to high temperature. All loops are supplied with deionized water from a central deionized water storage tank. Flow is controlled by multiple centrifugal pumps, and heat is dissipated via plate heat exchangers. The system is equipped with high-precision temperature sensors that feed the water temperature signal back to the control system in real time, ensuring that the cooling water temperature is maintained stably at a certain level. The set range.

[0029] 3) During data acquisition, the X-ray detection system 5 operates at a rate of... A total of 720 projected images were acquired at intervals. To achieve simultaneous monitoring of the surface morphology and temperature field of the test model, this device integrates a binocular vision imaging system 6 and an infrared temperature measurement system 7. The binocular vision imaging system 6 consists of two high-resolution, high-frame-rate industrial CCD cameras, which are rigidly fixed at a certain angle (approximately 15-30 degrees) to a finely adjustable optical platform. This platform is mounted on the observation window flange above the plasma test chamber via a metal bracket, with their optical axes intersecting at the stagnation point area of ​​the test model. The infrared temperature measurement system 7 uses a mid-wave infrared thermal imager, installed on a dedicated flange at the top of the test chamber. An infrared window is added to the center of the flange to ensure that the thermal imager can acquire infrared radiation information from the entire model surface. The installation positions of these two systems avoid interference with the X-ray path and the core area of ​​the plasma jet, and maintain synchronization with the X-ray acquisition system through trigger signal feedback. The infrared thermal imager acquires the surface temperature field at a frame rate of 100Hz, with high temperature measurement accuracy. 2%. The binocular vision imaging system 6 records surface topography changes at a frame rate of 50fps, with a spatial resolution of 2%. 100 m.

[0030] 4) In terms of data processing, a reconstruction algorithm is used to achieve time-resolved 3D reconstruction. Image registration and segmentation techniques are employed to quantitatively analyze defects such as pores and cracks within the material. The system ultimately achieves a 3D spatial resolution of [insert resolution here]. 10 m, which can clearly distinguish the evolution of the microstructure inside the material; Experimental verification shows that the device of this invention can characterize the internal microstructure evolution of thermal protection materials under real flight environments at the microscale. Multiple experiments have demonstrated the device's excellent reliability. Furthermore, the multimodal data fusion of the binocular vision imaging system 6 and the infrared thermography system 7 not only provides two-dimensional information on the ablation rate and temperature field distribution of the material surface morphology, but also allows for correlation and comparison of these surface parameters with three-dimensional microscopic damage mechanisms such as internal porosity evolution and crack propagation revealed by X-ray CT. This enables the study of the failure mechanism of thermal protection materials under extreme service environments at multiple scales, providing data support for the optimized design of materials. This in-situ detection capability provides important experimental evidence for the optimized design of thermal protection materials, filling a technological gap in this field.

[0031] Therefore, the present invention employs the above-mentioned in-situ X-ray tomography device for a plasma wind tunnel. After the plasma wind tunnel is started, a high-temperature gas flow is generated by a high-frequency plasma generator and accelerated by a nozzle to create a high-enthalpy gas flow environment in the plasma wind tunnel test chamber. The rotating mechanism and the thermal protection material stagnation test model are moved to the test area by the first electric displacement slide rail. The rotating structure rotates the test model, and the X-ray detection system combined with X-ray tomography imaging technology is used to achieve in-situ characterization of the three-dimensional microstructure information of the test sample.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An in-situ X-ray tomography device for a plasma wind tunnel, characterized in that: The system includes a plasma wind tunnel test chamber. A first electric displacement slide rail is installed on the bottom inner side of the plasma wind tunnel test chamber. A rotating mechanism is installed on the first electric displacement slide rail. The rotating mechanism includes a rotating motor. A sample clamp is installed at the front end of the rotating motor. An external thermal protection shell is provided on the outside of the rotating motor. The lower part of the external thermal protection shell is connected to a sample holder. The sample holder is fixedly installed on the first electric displacement slide rail.

2. The in-situ X-ray tomography device for a plasma wind tunnel according to claim 1, characterized in that: The outer thermal protection shell is equipped with a copper tube water cooling jacket, and the first water inlet and the first water outlet of the cooling circuit of the outer thermal protection shell are provided on one side of the outer thermal protection shell.

3. The in-situ X-ray tomography device for a plasma wind tunnel according to claim 1, characterized in that: A second water inlet for the cooling circuit of the sample holder is provided on one side of the bottom of the sample holder, and a second water outlet for the cooling circuit of the sample holder is provided on the sample holder opposite the second water inlet.

4. The in-situ X-ray tomography device for a plasma wind tunnel according to claim 1, characterized in that: The plasma wind tunnel test chamber is equipped with a double-layer water-cooled sandwich structure. A third water inlet and a third water outlet are located on one side of the bottom of the plasma wind tunnel test chamber, and an infrared temperature measurement system and a binocular vision imaging system are installed on its top.

5. The in-situ X-ray tomography device for a plasma wind tunnel according to claim 1, characterized in that: The sample fixture holds a heat protection material stagnation test model, which is a spherical cone structure with a ball head.

6. The in-situ X-ray tomography device for a plasma wind tunnel according to claim 1, characterized in that: An X-ray detection system is installed on one side of the plasma wind tunnel test chamber. The X-ray detection system is mounted on the second electric displacement slide rail and consists of an X-ray source and a flat panel detector.

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