A method and device for three-dimensional characterization of the combustion temperature of micro / nano fuel particles

Abstract

The application discloses a kind of micro / nano fuel particle combustion temperature three-dimensional characterization method and device.The present application controls high-speed camera, piezoelectric ceramic driver and piezoelectric ceramic actuator to carry out synchronous radiation signal capture and micro displacement control by synchronous control module.Micro / nano particle carrier platform drives substrate to be displaced downward by displacement amount of each Δz, and the flame image after each displacement is photographed by high-speed camera until micro / nano particle carrier platform moves downward to specified position;Obtain multiple groups of two-dimensional temperature data of fuel particle combustion flame to be measured, and draw multiple three-dimensional characterization maps according to multiple groups of two-dimensional temperature data of fuel particle combustion flame to be measured, to obtain temperature information at all times during combustion process.

Description

Technical Field

[0001] This invention belongs to the field of combustion temperature measurement technology for micro / nano fuel particles, specifically relating to a three-dimensional characterization method and apparatus for the combustion temperature of micro / nano fuel particles. Background Technology

[0002] With the rapid development of aerospace technology, supersonic vehicles, with their high efficiency and speed, have become an important direction for future aerospace exploration. In supersonic flight, the propulsion system has a crucial impact on the vehicle's performance, and solid fuel, due to its high energy density, storage safety, and stability, has become one of the main choices for supersonic propulsion systems. Especially under hypersonic conditions, the combustion characteristics of solid fuel have a decisive influence on the vehicle's thrust, efficiency, and thermal management performance.

[0003] In recent years, researchers have increasingly focused on the application of micro / nano fuel particles to further improve the performance of solid fuels. These micro / nano fuel particles, due to their high specific surface area and unique reaction characteristics, can significantly enhance combustion rates and efficiency. Simultaneously, their adaptability to extreme environments makes them an important research direction for propulsion system optimization. However, the combustion process of micro / nano fuel particles is extremely complex, involving rapid heat and mass transfer and multi-scale physicochemical processes. Their combustion temperature distribution directly affects combustion efficiency and exhaust emission characteristics. Therefore, accurate characterization of the combustion temperature of micro / nano fuel particles has become a core issue in studying their performance.

[0004] Currently, the measurement of combustion temperature for micro / nano fuel particles mainly relies on infrared thermal imaging and high-speed imaging techniques. However, these methods have significant limitations: infrared thermal imaging is limited by its temperature measurement range and struggles to capture rapid temperature changes during combustion; high-speed imaging is limited by frame rate and cannot fully capture the combustion process. Furthermore, these techniques only provide two-dimensional temperature information, making it difficult to measure the three-dimensional spatial distribution of the combustion process. This technological bottleneck severely restricts researchers' comprehensive understanding and optimized design of the combustion characteristics of micro / nano fuel particles.

[0005] To address the aforementioned issues, this invention proposes a novel method for three-dimensional characterization of the combustion temperature of micro / nano fuel particles, overcoming the shortcomings of existing technologies and providing a more comprehensive and accurate means of temperature measurement. This method not only breaks through the limitations of two-dimensional temperature measurement but also provides crucial data support for the thermodynamic analysis and performance optimization of the micro / nano fuel particle combustion process. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a three-dimensional characterization method and apparatus for the combustion temperature of micro / nano fuel particles.

[0007] A three-dimensional characterization method for the combustion temperature of micro / nano fuel particles, specifically including the following steps:

[0008] Step 1: Place the fuel particle to be tested on the substrate, and then fix the substrate above the micro / nano particle carrier platform S2; the micro / nano particle carrier platform S2 is fixed to the electric displacement platform by the piezoelectric ceramic actuator S1, and the electric displacement platform drives the micro / nano particle carrier platform S2 to move, so that the fuel particle to be tested in the substrate is located at the center of the high-speed camera imaging surface below the objective lens of the microscopic optical system S3; set the single displacement of the piezoelectric ceramic actuator in the axial direction as Δz.

[0009] Step 2: Initially, the high-speed camera's imaging surface is located on the substrate surface. Once the fuel particles begin to burn, the synchronization control module controls the high-speed camera to capture images and obtain the radiation signal from the initial imaging surface.

[0010] Step 3: After the high-speed camera captures the initial image, the piezoelectric ceramic actuator is driven by the synchronous control module, causing the micro / nano particle platform S2 and the substrate to move downwards by a displacement of Δz each time. The high-speed camera captures the flame image after each displacement until the micro / nano particle platform S2 moves downwards to the designated position. The height of the imaging plane relative to the substrate plane after the k-th movement is defined as... N sets of two-dimensional temperature data of the combustion flame of the fuel particles under test at different heights are obtained. After three-dimensional temperature reconstruction of the N sets of two-dimensional temperature data and the initial two-dimensional temperature data obtained in step two, the three-dimensional temperature distribution data of the combustion flame of the fuel particles under test during the detection period can be obtained.

[0011] The three-dimensional temperature reconstruction is as follows:

[0012] The Z-axis is obtained by combining N sets of two-dimensional flame temperature data at different heights measured by a high-speed camera with a colorimetric thermometry algorithm. k Two-dimensional temperature distribution at [location] ;

[0013] In the formula, m and n are the pixel coordinates obtained by the high-speed camera, and the initial time Z is... k =0.

[0014] With the relative positions of the microscopic optical system, high-speed camera, and S2 platform fixed, and the target surface of the high-speed camera perfectly collimated to the S2 platform, the high-speed camera is calibrated by placing a graduated microscopic scale on the S2 platform. This allows for the determination of the transformation relationship between the high-speed camera pixel coordinates (m, n, Z) and the actual physical coordinates (x, y, Z), i.e.: ;

[0015] In the formula, m and n are the image pixel coordinates, and P is the pixel coordinate to world coordinate transformation matrix.

[0016] After completing the coordinate transformation, we get:

[0017] ;

[0018] After performing k scans, Z is obtained. k Two-dimensional temperature distribution data Therefore, the three-dimensional temperature distribution of the target under test is represented by the following formula: ;

[0019] Linear interpolation is performed on the two-dimensional temperature distribution data of each layer, that is, for the temperature distribution data at Z... k With Z k+1 Temperature data at a point between layers This can be represented by the following formula: .

[0020] A three-dimensional temperature distribution map of the target under test is obtained during the detection cycle.

[0021] Step 4: Subsequently, the piezoelectric ceramic actuator is controlled by the synchronous control module to move the micro / nano particle carrier platform S2 and its upper substrate, so that the fuel particle to be tested is located at the center of the high-speed camera imaging plane below the objective lens of the microscopic optical system S3. Step 3 is repeated multiple times until the combustion flame is extinguished, obtaining multiple sets of two-dimensional temperature data of the combustion flame of the fuel particle to be tested. Based on the multiple sets of two-dimensional temperature data of the combustion flame of the fuel particle to be tested, multiple three-dimensional temperature distribution maps are plotted to obtain temperature information at all moments during the combustion process.

[0022] To achieve the above method, a three-dimensional characterization device for the combustion temperature of micro / nano fuel particles is provided. The device includes a high-speed camera, a synchronous control module, a piezoelectric ceramic actuator, an electric displacement platform, a piezoelectric ceramic actuator S1, a micro / nano particle carrier platform S2, and a microscopic optical system S3.

[0023] The high-speed camera, the objective lens of the microscopic optical system S3, the micro / nano particle carrier platform S2, and the piezoelectric ceramic actuator S1 are all located on the same axis. The micro / nano particle carrier platform S2 and the piezoelectric ceramic actuator S1 are fastened together. The piezoelectric ceramic actuator S1 is controlled by the piezoelectric ceramic driver and fixed above the electric displacement platform.

[0024] The micro / nano particle carrier platform S2 is a platform for placing a substrate carrying the fuel particles to be tested. To ensure imaging effect, a through hole is opened in the middle of the micro / nano particle carrier platform S2.

[0025] The two-dimensional image sensor inside the high-speed camera acquires the radiation signal that forms an "imaging surface" above the micro / nano particle carrier platform S2 through the objective lens of the micro-optical system S3; the micro / nano fuel particles in the substrate above the micro / nano particle carrier platform S2 can be moved to the imaging surface of the high-speed camera through the electric displacement platform.

[0026] The synchronous control module controls a high-speed camera, a piezoelectric ceramic driver, and a piezoelectric ceramic actuator to capture synchronous radiation signals and control minute displacements.

[0027] The piezoelectric ceramic actuator can receive digital or analog signals and output a working voltage to the piezoelectric ceramic actuator according to the received signal. The piezoelectric ceramic actuator deforms in the axial direction according to the working voltage output by the actuator, thereby realizing the displacement of the micro / nano particle carrier platform S2 and the substrate above it.

[0028] The piezoelectric ceramic actuator and the piezoelectric ceramic driver work together to achieve controllable micro-displacement based on the signal sent by the synchronous control module.

[0029] A microscopic optical system is an optical component with a microscope objective as its main body, which, together with a lens, achieves microscopic imaging.

[0030] High-speed cameras are used to extract radiation signals of specific wavelengths from the corresponding pixel channels of the imaging plane. The radiation signals are converted into voltage signals by the internal circuitry of the system, and finally converted into digital image data by the analog-to-digital converter module.

[0031] After calibration, a high-speed camera can measure the radiation signal of a specific wavelength of the object under test. The radiation signal of a specific wavelength in the radiation signal captured by the high-speed camera through the imaging surface is converted into the temperature of the target under test by using a colorimetric thermometry formula, so as to realize the two-dimensional temperature distribution characterization of a certain imaging surface of the target under test.

[0032] Preferably, the piezoelectric ceramic actuator is a Chipstar XE-509.S3 model, and the piezoelectric ceramic driver is a Chipstar E503 model. The high-speed camera is a high-speed CMOS camera or a high-speed CCD camera. The electric displacement platform used is a TSA50-C&&CZF40-200 model.

[0033] Furthermore, the aforementioned microscopic optical system also includes a neutral density filter for adjusting the radiance of the flame under test.

[0034] Furthermore, the calibration of the high-speed camera includes offline calibration and online calibration;

[0035] The offline calibration process is as follows:

[0036] The operating temperature of the blackbody furnace was set, gradually increasing from 800℃ to 3000℃ in 100℃ increments. Images of the blackbody furnace target surface were captured and sampled using a fixed white balance curve and imaging parameters. After acquiring the image signal at each temperature point, the average value of the central region of the target surface was calculated to obtain the average measurement value of the RGB three channels at each temperature calibration point. Since the blackbody furnace radiation signal satisfies the blackbody radiation law, the measured values ​​at these temperature calibration points can be compared with the theoretical radiation intensity at the three wavelengths of blackbody radiation. By comparison, the correction value Kt at each temperature point can be obtained. ;

[0037] In the formula, This refers to the real-time temperature of the blackbody furnace. For camera , The wavelength measured at the center of pixel B is used as the reference. The spectral response curve of the high-speed camera can be obtained by performing least-squares fitting on the correction value Kt at each temperature point. Combining the spectral response curve The RGB three-channel measurements from the camera can accurately characterize the radiation signal of the target at a specific wavelength, and then the temperature of the target can be obtained through the colorimetric thermometry formula, i.e.: .

[0038] In the formula, r, g, and b are the response values ​​of each pixel channel of the two-dimensional spatial resolution colorimetric thermometer, respectively. The spectral response curve of a high-speed CMOS camera; The center wavelength corresponding to each pixel channel of a two-dimensional spatially resolved colorimetric thermometer. The second radiation constant, =hc / k=1.4388×10^(-2) m·K, obtained from Planck's blackbody radiation law.

[0039] After offline calibration, online calibration is required to correct the influence of spectral transmittance in the microscopic optical components on temperature measurement. The online calibration yields the high-speed camera coupling spectral correction coefficient A2 to correct the influence of the optical path on the spectral information of the radiation signal. The specific steps are as follows:

[0040] First, a calibrated standard halogen tungsten lamp is placed on the imaging plane at the front of the microscope objective. The lamp is then powered on and preheated to ensure operational stability. After preheating, a high-speed camera is used to acquire signals. The image data obtained from the high-speed camera is processed, and the average value of the central region of the halogen tungsten lamp target surface in the captured image is calculated to obtain the average three-channel measurement value for each pixel. .

[0041] Then, the high-speed camera was directly aimed at the halogen lamp (without passing through the microscopic optical system), and the radiation signal was acquired using the high-speed camera. The image data captured by the high-speed camera was recorded, and the average value of the central area of ​​the halogen lamp target surface in the captured image was calculated to obtain the average measurement value of each pixel in three channels. .

[0042] Finally, based on the recorded data, the CMOS camera spectral correction coefficient A2 is obtained. The expression for A2 is as follows:

[0043] .

[0044] The two-dimensional spatial distribution of the system's imaging surface is characterized as follows:

[0045] ;

[0046] In the formula, r, g, and b are the response values ​​of each pixel channel of the two-dimensional spatial resolution colorimetric thermometer, respectively. The spectral response curve of the high-speed camera; The center wavelength corresponding to each pixel channel of a two-dimensional spatially resolved colorimetric thermometer. The second radiation constant, =hc / k=1.4388×10^(-2) m·K, obtained from Planck's blackbody radiation law.

[0047] This invention overcomes the limitations of traditional technologies that can only acquire two-dimensional temperature information, achieving three-dimensional spatial temperature distribution characterization during the combustion process of micro / nano fuel particles. Addressing the small physical size and short combustion time of micro / nano fuel particles, this invention employs a platform displacement mechanism based on piezoelectric ceramics and a synchronous control system in the device design. The rapid response characteristics of piezoelectric ceramics enable precise adjustment of the imaging surface height. Combined with the synchronous control system, this achieves real-time capture of the combustion process and simultaneous acquisition of multi-dimensional temperature information, significantly improving the temporal and spatial resolution of the measurement system and enabling accurate characterization of the three-dimensional temperature gradient distribution during the combustion process of micro / nano fuel particles.

[0048] Precise characterization of the three-dimensional temperature gradient distribution during the combustion process of micro / nano fuel particles provides more comprehensive data support for in-depth research on combustion mechanisms, facilitating the design and improvement of micro / nano fuel particles. It can also be widely applied to research on the combustion processes of micro / nano fuel particles in aerospace, energy, materials, chemical engineering, and other fields, providing new tools and ideas for multidisciplinary technological development. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the overall structure of the device described in this invention;

[0050] Figure 2-4This is a three-dimensional distribution diagram of the combustion temperature of the target under test at different times in the embodiment. Detailed Implementation

[0051] The present invention will be further described below with reference to the accompanying drawings.

[0052] like Figure 1 As shown, a three-dimensional characterization device for the combustion temperature of micro / nano fuel particles includes a high-speed camera, a synchronous control module, a piezoelectric ceramic actuator, an electric displacement platform, a piezoelectric ceramic actuator S1, a micro / nano particle carrier platform S2, and a microscopic optical system S3.

[0053] The high-speed camera, the objective lens of the microscopic optical system S3, the micro / nano particle carrier platform S2, and the piezoelectric ceramic actuator S1 are all located on the same axis. The micro / nano particle carrier platform S2 and the piezoelectric ceramic actuator S1 are fastened together by bolts and nuts. The piezoelectric ceramic actuator S1 is controlled by the piezoelectric ceramic driver and is fixed above the electric displacement platform by bolts and nuts.

[0054] The micro / nano particle carrier platform S2 is a platform for placing a substrate carrying the fuel particles to be tested. To ensure imaging quality, a through hole is opened in the middle of the micro / nano particle carrier platform S2. In this embodiment, the substrate is a glass slide.

[0055] The two-dimensional image sensor inside the high-speed camera acquires the radiation signal that forms an "imaging surface" above the micro / nano particle carrier platform S2 through the objective lens of the micro-optical system S3; the electric displacement platform has a large displacement stroke, which can move the micro / nano fuel particles in the substrate above the micro / nano particle carrier platform S2 to the imaging surface of the high-speed camera.

[0056] The synchronous control module controls a high-speed camera, a piezoelectric ceramic driver, and a piezoelectric ceramic actuator to capture synchronous radiation signals and control minute displacements.

[0057] A piezoelectric ceramic actuator is a displacement device capable of achieving unidirectional nanometer-level resolution displacement with a stroke of up to 260 micrometers and a displacement response time in the microsecond range. In this device, axial displacement is achieved using a piezoelectric ceramic actuator. In this embodiment, the piezoelectric ceramic actuator selected is the Xinmingtian model XE-509.S3.

[0058] The piezoelectric ceramic actuator can receive digital or analog signals and output a working voltage to the piezoelectric ceramic actuator according to the received signal. The piezoelectric ceramic actuator deforms in the axial direction according to the working voltage output by the actuator, thereby realizing the displacement of the micro / nano particle carrier platform S2 and the substrate above it. In this embodiment, the piezoelectric ceramic actuator selected is the Xinmingtian E503 model.

[0059] The piezoelectric ceramic actuator and the piezoelectric ceramic driver work together to achieve controllable micro-displacement based on the signal sent by the synchronous control module.

[0060] The microscopic optical system is an optical component with a microscope objective as its main body. The microscope objective, together with the lens, realizes microscopic imaging. The optical system also includes a neutral density filter to adjust the radiation brightness of the flame under test.

[0061] The electric displacement platform is a platform capable of displacement in the x, y, and z directions. Its working principle involves converting the rotation angle of a stepper motor into a displacement in a specific direction using a ball screw. The purpose is to move the fuel particle being measured to the center of the imaging surface through displacement in the X, Y, and Z directions. The electric displacement platform used in this embodiment is model (TSA50-C & CZF40-200), with a maximum displacement speed of 10 mm / s and a minimum displacement resolution of 0.625 μm.

[0062] High-speed cameras are used to extract specific wavelength radiation signals from corresponding pixel channels on the imaging surface. Internal circuitry converts these radiation signals into voltage signals, which are then converted into digital image data via an analog-to-digital converter. After calibration, the high-speed camera can measure specific wavelength radiation signals from the object under test. A colorimetric thermometry formula is used to convert the specific wavelength radiation signals captured by the high-speed camera and transmitted through the imaging surface into the temperature of the target object, thus characterizing the two-dimensional temperature distribution of a specific imaging surface of the target object.

[0063] According to Planck's formula, the radiation intensity of a non-blackbody ; For wavelength, For temperature, Let be the emissivity of the object. When Planck's formula can be simplified to Wien's formula at this time, where the radiation intensity In the formula, the first radiation constant is... Second radiation constant h is Planck's constant, c is the speed of light, and k is Boltzmann's constant.

[0064] The colorimetric temperature measurement formula is: In the formula Indicates temperature. The second radiation constant, , Representing different wavelengths, , This represents the radiation intensity of radiation signals at different wavelengths.

[0065] The high-speed camera used in this implementation is a high-speed CMOS camera. The high-speed CMOS camera has a Bayer filter at the front. The radiation signal of the fuel particle under test is converted into a specific wavelength radiation signal after passing through the Bayer filter, and then transmitted to the photodiodes in the pixel array of the high-speed camera. Each pixel photodiode converts the received specific wavelength radiation signal into an electric charge, which is then read and amplified by row and column scanning circuits. Finally, the analog signal is converted into a digital signal by an analog-to-digital converter, realizing the extraction of the specific wavelength radiation signal of the fuel particle under test. To ensure accurate characterization of the two-dimensional radiation signal at a certain height of the target, the high-speed camera still needs to be calibrated offline and online before use.

[0066] The offline calibration process for a high-speed CMOS camera is as follows:

[0067] The operating temperature of the blackbody furnace was set, gradually increasing from 800℃ to 3000℃ in 100℃ increments. Images of the blackbody furnace target surface were captured and sampled using a fixed white balance curve and imaging parameters. After acquiring image signals at each temperature point, the average value of the central region of the target surface was calculated to obtain the average measurement values ​​of the RGB three channels at each temperature calibration point. Since the blackbody furnace radiation signal satisfies the blackbody radiation law, the measured values ​​at these temperature calibration points can be compared with the theoretical radiation intensity at the three wavelengths of blackbody radiation. By comparison, the correction value Kt at each temperature point can be obtained. ;

[0068] In the formula, This refers to the real-time temperature of the blackbody furnace. For camera , , The wavelength measured at the center of the pixel channel. The spectral response curve of the high-speed CMOS camera can be obtained by performing least-squares fitting on the correction value Kt at each temperature point. Combining the spectral response curve The RGB three-channel measurements from the camera can accurately characterize the radiation signal of the target at a specific wavelength, and then the temperature of the target can be obtained through the colorimetric thermometry formula, i.e.: .

[0069] In the formula, r, g, and b are the response values ​​of each pixel channel of the two-dimensional spatial resolution colorimetric thermometer, respectively. The spectral response curve of a high-speed CMOS camera; The center wavelength corresponding to each pixel channel of a two-dimensional spatially resolved colorimetric thermometer. The second radiation constant, =hc / k=1.4388×10^(-2) m·K, obtained from Planck's blackbody radiation law.

[0070] After offline calibration, online calibration is required to correct the influence of spectral transmittance in the microscopic optical components on temperature measurement. The online calibration yields the CMOS camera coupling spectral correction coefficient A2 to correct the influence of the optical path on the spectral information of the radiation signal. The specific steps are as follows:

[0071] First, a calibrated standard halogen tungsten lamp is placed on the imaging plane at the front of the microscope objective. The lamp is powered on and preheated to ensure operational stability. After preheating, a high-speed CMOS camera is used for signal acquisition. The image data acquired by the high-speed CMOS camera is processed, and the average value of the central region of the halogen tungsten lamp target surface in the acquired image is calculated to obtain the average three-channel measurement value of each pixel. .

[0072] Then, the high-speed CMOS camera was directly pointed at the halogen lamp (without passing through the microscopic optical system), and the radiation signal was acquired using the high-speed CMOS camera. The image data captured by the high-speed CMOS camera was recorded, and the average value of the central area of ​​the halogen lamp target surface in the captured image was calculated to obtain the average measurement value of each pixel in three channels. .

[0073] Finally, based on the recorded data, the CMOS camera spectral correction coefficient A2 is obtained. The expression for A2 is as follows:

[0074] .

[0075] The two-dimensional spatial distribution of the system's imaging surface is characterized as follows:

[0076] ;

[0077] In the formula, r, g, and b are the response values ​​of each pixel channel of the two-dimensional spatial resolution colorimetric thermometer, respectively. The spectral response curve of a high-speed CMOS camera; The center wavelength corresponding to each pixel channel of a two-dimensional spatially resolved colorimetric thermometer. The second radiation constant, =hc / k=1.4388×10^(-2) m·K, obtained from Planck's blackbody radiation law.

[0078] Based on the above device, a three-dimensional characterization method for the combustion temperature of micro / nano fuel particles is provided, which specifically includes the following steps:

[0079] Step 1: Place the fuel particle to be tested on the substrate, and then fix the substrate above the micro / nano particle carrier platform S2. The micro / nano particle carrier platform S2 is fixed to the electric platform by a piezoelectric ceramic actuator S1. The electric platform drives the micro / nano particle carrier platform S2 to move, so that the fuel particle to be tested in the substrate is located at the center of the high-speed camera imaging plane below the objective lens of the microscopic optical system S3. Set the single axial displacement of the piezoelectric ceramic actuator as Δz.

[0080] In this embodiment, Δz is 0.6 μm, and the high-speed camera shooting time and mechanical displacement establishment time are both less than 10 μs.

[0081] Step 2: Initially, the high-speed camera's imaging surface is located on the substrate surface. After the fuel particles begin to burn, the synchronization control module controls the high-speed camera to capture images and obtain the radiation signal from the initial imaging surface.

[0082] Step 3: After the high-speed camera captures the initial image, the piezoelectric ceramic actuator is driven by the synchronous control module, causing the micro / nano particle platform S2 and the substrate to move downwards by a displacement of Δz each time. The high-speed camera captures the flame image after each displacement until the micro / nano particle platform S2 can no longer move downwards. The height of the imaging plane relative to the substrate plane after the k-th displacement is defined as... N sets of two-dimensional temperature data of the combustion flame of the fuel particles under test at different heights are obtained. After three-dimensional temperature reconstruction of the N sets of two-dimensional temperature data and the initial two-dimensional temperature data obtained in step two, the three-dimensional temperature distribution data of the combustion flame of the fuel particles under test at a certain time period (generally one moving cycle of the piezoelectric ceramic actuator) can be obtained.

[0083] The three-dimensional temperature reconstruction is as follows:

[0084] The Z-axis is obtained by combining N sets of two-dimensional flame temperature data at different heights measured by a high-speed camera with a colorimetric thermometry algorithm. k Two-dimensional temperature distribution at [location] ;

[0085] In the formula, m and n are the pixel coordinates obtained by the high-speed camera, and the initial time Z is... k =0.

[0086] To achieve the mutual conversion between pixel coordinates and world coordinates in the actual physical world, under the condition that the relative positions of the microscopic optical system, high-speed CMOS camera, and S2 platform are fixed and the target surface of the high-speed camera is completely collimated to the S2 platform, the high-speed camera is calibrated by placing a graduated microscopic ruler on the S2 plane, thereby obtaining the conversion relationship between the pixel coordinates (m, n, Z) of the high-speed camera and the actual coordinates (x, y, Z) in the physical world, that is: ;

[0087] In the formula, m and n are the image pixel coordinates, and P is the pixel coordinate to world coordinate transformation matrix.

[0088] After completing the coordinate transformation, we get:

[0089] ;

[0090] After N scans, Z is obtained. k Two-dimensional temperature distribution data Therefore, the three-dimensional temperature distribution of the target under test is represented by the following formula: ;

[0091] Linear interpolation is performed on the two-dimensional temperature distribution data of each layer, that is, for the temperature distribution data at Z... k With Z k+1 Temperature data at a point between layers This can be represented by the following formula: .

[0092] A three-dimensional temperature distribution map of the target object during that time period is obtained.

[0093] Step 4: Subsequently, the piezoelectric ceramic actuator is controlled by the synchronous control module to move the micro / nano particle carrier platform S2 and its upper substrate, so that the fuel particle to be tested is located at the center of the high-speed camera imaging plane below the objective lens of the microscopic optical system S3. Step 3 is repeated multiple times until the combustion flame is extinguished, obtaining multiple sets of two-dimensional temperature data of the combustion flame of the fuel particle to be tested. Based on the multiple sets of two-dimensional temperature data of the combustion flame of the fuel particle to be tested, multiple three-dimensional temperature distribution maps are obtained, providing temperature information at all moments during the combustion process, i.e., multiple three-dimensional temperature distribution maps with time scales.

[0094] In this embodiment, the effectiveness of the above method is demonstrated by selecting micron-sized aluminum as the sample to be tested, as detailed below:

[0095] The sample to be tested (micrometer-sized aluminum) is placed in the center of the S2 platform. After the micrometer-sized aluminum is ignited, the high-speed camera is controlled by the synchronous control module to capture the radiation image. At the same time, the piezoelectric ceramic driver is synchronously controlled to output a drive signal, thereby driving the piezoelectric ceramic to achieve displacement. The high-speed camera has a resolution of 512*512, and the pixel size has been calibrated in advance (0.7μm / Pixel). The high-speed camera exposure time is set to 5 microseconds, the sampling frame rate is set to 10,000 frames, and the EDR is kept the same as the exposure. The piezoelectric ceramic control signal frequency is 10,000Hz. The piezoelectric ceramic controller signal frequency is the same as the camera sampling frame rate to ensure that the two-dimensional temperature information of the flame at the specified height is obtained.

[0096] The piezoelectric ceramic controller is set to a single displacement of 1 micrometer, and performs 10 single-step displacements in a single scan cycle. This yields 10 flame radiation signal images at different heights within a single cycle. The flame images are then converted into flame temperature using a colorimetric thermometry algorithm, and combined with... and This allows us to obtain the three-dimensional temperature distribution of the target object within one detection cycle. Repeated measurements are performed to obtain the three-dimensional temperature distribution at all times during the combustion process. The three-dimensional temperature measurement results of the target object (micrometer-sized aluminum) are as follows: Figure 2-4 As shown.

Claims

1. A three-dimensional characterization method for the combustion temperature of micro / nano fuel particles, characterized in that: Specifically, the steps include the following: Step 1: Place the fuel particle to be tested on the substrate, and then fix the substrate above the micro / nano particle carrier platform S2; the micro / nano particle carrier platform S2 is fixed to the electric displacement platform by the piezoelectric ceramic actuator S1, and the electric displacement platform drives the micro / nano particle carrier platform S2 to move, so that the fuel particle to be tested in the substrate is located at the center of the high-speed camera imaging surface below the objective lens of the microscopic optical system S3; set the single axial displacement of the piezoelectric ceramic actuator as Δz; Step 2: Initially, the high-speed camera's imaging surface is located on the substrate surface. Once the fuel particles begin to burn, the synchronous control module controls the high-speed camera to capture images and obtain the radiation signal from the initial imaging surface. Step 3: After the high-speed camera captures the initial image, the piezoelectric ceramic actuator is driven by the synchronous control module, causing the micro / nano particle platform S2 and the substrate to move downwards by a displacement of Δz each time. The high-speed camera captures the flame image after each displacement until the micro / nano particle platform S2 moves downwards to the designated position. The height of the imaging plane relative to the substrate plane after the k-th movement is defined as... N sets of two-dimensional temperature data of the combustion flame of the fuel particles under test at different heights are obtained. After three-dimensional temperature reconstruction of the N sets of two-dimensional temperature data and the initial two-dimensional temperature data obtained in step two, the three-dimensional temperature distribution data of the combustion flame of the fuel particles under test during the detection period can be obtained. The three-dimensional temperature reconstruction is as follows: The Z-axis is obtained by combining N sets of two-dimensional flame temperature data at different heights measured by a high-speed camera with a colorimetric thermometry algorithm. k Two-dimensional temperature distribution at [location] ; In the formula, m and n are the pixel coordinates obtained by the high-speed camera, and the initial time Z is... k =0; With the relative positions of the microscopic optical system, high-speed camera, and S2 platform fixed, and the target surface of the high-speed camera perfectly collimated to the S2 platform, the high-speed camera is calibrated by placing a graduated microscopic scale on the S2 platform. This allows for the determination of the transformation relationship between the high-speed camera pixel coordinates (m, n, Z) and the actual physical coordinates (x, y, Z), i.e.: ; In the formula, m,n are the image pixel coordinates, and P is the pixel coordinate to world coordinate transformation matrix; After completing the coordinate transformation, we get: ； After performing k scans, Z is obtained. k Two-dimensional temperature distribution data Therefore, the three-dimensional temperature distribution of the target under test is represented by the following formula: ; Linear interpolation is performed on the two-dimensional temperature distribution data of each layer, that is, for the temperature distribution data at Z... k With Z k+1 Temperature data at a point between layers This can be represented by the following formula: ; A three-dimensional temperature distribution map of the target under test is obtained during the detection cycle; Step 4: Subsequently, the piezoelectric ceramic actuator is controlled by the synchronous control module to move the micro / nano particle carrier platform S2 and its upper substrate, so that the fuel particle to be tested is located at the center of the high-speed camera imaging surface below the objective lens of the microscopic optical system S3; the operation of step 3 is repeated multiple times until the combustion flame is extinguished, and multiple sets of two-dimensional temperature data of the combustion flame of the fuel particle to be tested are obtained; based on the multiple sets of two-dimensional temperature data of the combustion flame of the fuel particle to be tested, multiple three-dimensional temperature distribution maps are drawn, thus obtaining the temperature information at all moments during the combustion process.

2. To achieve the method described in claim 1, a three-dimensional characterization device for the combustion temperature of micro / nano fuel particles is provided, characterized in that: It includes a high-speed camera, a synchronization control module, a piezoelectric ceramic actuator, an electric displacement platform, a piezoelectric ceramic actuator S1, a micro / nano particle carrier platform S2, and a microscopic optical system S3; The high-speed camera, the objective lens of the microscopic optical system S3, the micro / nano particle carrier platform S2, and the piezoelectric ceramic actuator S1 are all located on the same axis. The micro / nano particle carrier platform S2 and the piezoelectric ceramic actuator S1 are fastened together. The piezoelectric ceramic actuator S1 is controlled by the piezoelectric ceramic driver and fixed above the electric displacement platform. The micro / nano particle carrier platform S2 is a platform for placing a substrate carrying the fuel particles to be tested. To ensure imaging effect, a through hole is opened in the middle of the micro / nano particle carrier platform S2. The two-dimensional image sensor inside the high-speed camera acquires the radiation signal that forms an "imaging surface" above the micro / nano particle carrier platform S2 through the objective lens of the micro-optical system S3; the micro / nano fuel particles on the substrate above the micro / nano particle carrier platform S2 can be moved to the imaging surface of the high-speed camera through the electric displacement platform. The synchronous control module controls a high-speed camera, a piezoelectric ceramic actuator, and a piezoelectric ceramic actuator to capture synchronous radiation signals and control minute displacements. The piezoelectric ceramic actuator can receive digital or analog signals and output a working voltage to the piezoelectric ceramic actuator according to the received signal. The piezoelectric ceramic actuator deforms in the axial direction according to the working voltage output by the actuator, thereby realizing the displacement of the micro / nano particle carrier platform S2 and the substrate above it. The piezoelectric ceramic actuator and the piezoelectric ceramic driver work together to achieve controllable micro-displacement based on the signal sent by the synchronous control module; A microscopic optical system is an optical component with a microscope objective as its main body, which, together with a lens, achieves microscopic imaging. High-speed cameras are used to extract specific wavelength radiation signals from the corresponding pixel channels of the imaging plane. The radiation signals are converted into voltage signals by the internal circuitry of the system, and finally converted into digital image data by the analog-to-digital converter module. After calibration, the high-speed camera can measure the radiation signal of a specific wavelength of the object under test. The colorimetric thermometry formula is used to convert the radiation signal of a specific wavelength in the radiation signal captured by the high-speed camera through the imaging surface into the temperature of the target under test, so as to realize the two-dimensional temperature distribution characterization of a certain imaging surface of the target under test.

3. The apparatus as described in claim 2, characterized in that: The piezoelectric ceramic actuator is selected from the Xinmingtian XE-509.S3 piezoelectric ceramic actuator, and the piezoelectric ceramic driver is selected from the Xinmingtian E503 piezoelectric ceramic driver.

4. The apparatus as described in claim 2, characterized in that: The aforementioned microscopic optical system also includes a neutral density filter for adjusting the radiance of the flame under test.

5. The apparatus as described in claim 2, characterized in that: The high-speed camera mentioned is a high-speed CMOS camera or a high-speed CCD camera.

6. The apparatus as claimed in claim 2, characterized in that: The electric displacement platform used is model TSA50-C&&CZF40-200.

7. The apparatus as claimed in claim 2, characterized in that: The calibration of the high-speed camera includes offline calibration and online calibration; The offline calibration process is as follows: The operating temperature of the blackbody furnace was set, gradually increasing from 800℃ to 3000℃ in 100℃ increments. Images of the blackbody furnace target surface were captured and sampled using a fixed white balance curve and imaging parameters. After acquiring the image signal at each temperature point, the average value of the central region of the target surface was calculated to obtain the average measurement value of the RGB three channels at each temperature calibration point. Since the blackbody furnace radiation signal satisfies the blackbody radiation law, the measured values ​​at these temperature calibration points can be compared with the theoretical radiation intensity at the three wavelengths of blackbody radiation. By comparison, the correction value Kt at each temperature point can be obtained. ; In the formula, T0 is the real-time temperature of the blackbody furnace. For camera , , The wavelength measured at the center of the pixel channel; after performing least-squares fitting on the correction value Kt at each temperature point, the spectral response curve of the high-speed camera can be obtained. Combined with spectral response curves The RGB three-channel measurements from the camera can accurately characterize the radiation signal of the target at a specific wavelength, and then the temperature of the target can be obtained through the colorimetric thermometry formula, i.e.: ; In the formula, r, g, and b are the response values ​​of each pixel channel of the two-dimensional spatial resolution colorimetric thermometer, respectively. The spectral response curve of the high-speed camera; The center wavelength corresponding to each pixel channel of a two-dimensional spatially resolved colorimetric thermometer. The second radiation constant, =hc / k=1.4388×10^(-2) m·K, obtained from Planck's blackbody radiation law; After offline calibration, online calibration is required to correct the influence of spectral transmittance in the microscopic optical components on temperature measurement. The online calibration yields the high-speed camera coupling spectral correction coefficient A2 to correct the influence of the optical path on the spectral information of the radiation signal. The specific steps are as follows: First, a calibrated standard halogen tungsten lamp is placed on the imaging plane at the front of the microscope objective. The halogen tungsten lamp is powered on and preheated to ensure operational stability. After preheating, a high-speed camera is used to acquire signals. The average value of the central area of ​​the halogen tungsten lamp target surface in the captured image is calculated to obtain the average three-channel measurement value of each pixel. ; Then, the high-speed camera was directly aimed at the halogen lamp, and radiation signals were acquired using the high-speed camera. The image data captured by the high-speed camera was recorded, and the average value of the central area of ​​the halogen lamp target surface in the captured image was calculated to obtain the average measurement value of each pixel across three channels. ; Finally, based on the recorded data, the high-speed camera spectral correction coefficient A2 is obtained; the expression for A2 is as follows: ； The two-dimensional spatial distribution of the system's imaging surface is characterized as follows: ； In the formula, r, g, and b are the response values ​​of each pixel channel of the two-dimensional spatial resolution colorimetric thermometer, respectively. The spectral response curve of the high-speed camera; The center wavelength corresponding to each pixel channel of a two-dimensional spatially resolved colorimetric thermometer. The second radiation constant, =hc / k=1.4388×10^(-2) m·K, obtained from Planck's blackbody radiation law.

Images