A System and Method for Measuring the Three-Dimensional Temperature Field of Gas Combustion Based on Thermal Imaging and TDLAT

Abstract

A system and method for measuring the three-dimensional combustion temperature field of gas based on thermal imaging and TDLAT (Total Thermal Imager and TDLAT) is proposed. This system and method utilizes TDLAT temperature field measurement technology to address the problem of excessive computational load and long measurement time caused by eliminating ghost points in existing TDLAT temperature field measurements. The system and method send control signals to two laser controllers via a data processing module to control the two lasers to operate in a time-sharing manner and output lasers of different frequencies. After laser beam combining, the laser beams enter several laser emitters. The electrical signals generated by the laser receivers are acquired by a data acquisition card. The data processing module calculates the temperature at various locations in the measured field based on the acquired data and determines the location of high-temperature points by combining the temperature distribution map obtained by an infrared thermal imager. This application can avoid the generation of ghost points or eliminate ghost points using an infrared thermal imager, significantly improving measurement efficiency and enabling real-time detection of the combustion status of marine diesel engines.

Description

Technical Field

[0001] This application relates to diesel engine combustion chambers, specifically to a technique for measuring the flame temperature field at the outlet position of a diesel engine combustion chamber based on TDLAS technology. Background Technology

[0002] As the "heart" of a diesel engine, the combustion chamber's combustion state directly reflects the engine's operating process, exhaust emissions, and combustion efficiency. Monitoring the combustion state allows for the diagnosis of the combustion chamber's current health and prediction of performance trends, ensuring the engine's safe and reliable operation. Therefore, combustion diagnosis of the combustion chamber is essential. The flame temperature within the combustion chamber is a crucial physical quantity. On one hand, the atomization, mixing, and pulsating of fuel within the combustion chamber cause dynamic changes in the combustion flame, resulting in corresponding changes in flame temperature. Monitoring these changes allows for the assessment of the fuel's combustion state. On the other hand, with the development of combustion chambers, the temperature at the combustion chamber outlet has continuously increased, exceeding the melting point of high-temperature alloy materials. Therefore, measuring the flame temperature at the combustion chamber outlet provides important theoretical basis for developing suitable high-temperature alloy materials for combustion chamber construction. Thus, accurate diagnosis of the flame temperature at the combustion chamber outlet is of significant guiding importance for improving combustion efficiency, reducing pollutant emissions, and extending engine lifespan.

[0003] Tunable semiconductor absorption spectroscopy (TDLAS) is a type of laser diagnostic technology, and its principle is as follows: Figure 1As shown, the laser outputs a specific wavelength of light under the control of the signal generator. The light intensity attenuates after passing through the gas being measured, and the attenuated intensity is measured by a detector and calculated by a host computer. The calculation principle is as follows: based on the Beer-Lambert theorem, the average concentration information of the measured component is calculated through the one-to-one correspondence between the spectral absorbance of monochromatic light and the concentration of the measured gas. TDLAT (Tunable Diode Laser Absorption Tomography) features high safety, high sensitivity, high accuracy, and fast response speed. Currently, laser-based temperature measurement methods mainly include point measurement, optical path path integration measurement, and imaging technology. However, when the measurement target is to provide quantitative, spatial, and temporally resolved temperature information in actual combustion, these methods have certain limitations. Temperature measurement methods combining computed tomography (CT) and tunable laser absorption tomography (TDLAT) can overcome these limitations. TDLAT (Transient Thermal Atmoscopy) utilizes the principles of CT (Computed Tomography) to divide the measured spatial region into numerous grids. TDLAT integrated absorbance measurements are then performed along the grid lines, and algorithms are used to obtain absorption information at grid intersections, thus yielding the temperature distribution of the entire field. TDLAT-based bilinear thermometry, with its significantly lower requirements for optical components and computational resources compared to hyperspectral tomography, has become the mainstream method in the field of TDLAT temperature imaging. However, when reconstructing two-dimensional / three-dimensional temperature fields using this technique, if multiple high-temperature points exist, the reconstructed temperature field will contain "phantom points"—locations where the calculated temperature is high but the actual temperature is not. Existing technologies mostly employ convolutional neural network iterative algorithms or machine vision to filter out these "phantom points," but this results in long data processing times, impacting the speed of real-time online measurements. Summary of the Invention

[0004] To address or mitigate the above problems, this application provides a gas three-dimensional combustion temperature field measurement system and method based on thermal imaging and TDLAT.

[0005] The gas three-dimensional combustion temperature field measurement system based on thermal imaging and TDLAT of this application includes: a first laser controller, a second laser controller, a first laser, a second laser, a beam combiner, a beam splitter, several laser emitters, several laser receivers, a mounting bracket, a support structure capable of extending and retracting in the vertical direction, an infrared thermal imager, a data acquisition card, and a data processing module; the mounting bracket is fixed to a part of the support structure, and the area to be measured is located within the area enclosed by the mounting bracket;

[0006] The infrared thermal imager is used to image the area to be tested; a plurality of laser emitters are arranged on the mounting bracket, the lasers emitted by the plurality of laser emitters are located in the plane of the mounting bracket, and the propagation paths of the lasers emitted by the plurality of laser emitters are evenly distributed throughout the area to be tested; a plurality of laser receivers are arranged on the mounting bracket, and the plurality of laser emitters and the plurality of laser receivers correspond one-to-one; the data processing module sends control signals to the first laser controller and the second laser controller through the data acquisition card, and receives data acquired by the plurality of laser receivers; the first laser controller and the second laser controller control the first laser and the second laser respectively according to the received control signals; the lasers of different frequencies output by the first laser and the second laser sequentially enter the beam combiner and the beam splitter and are divided into a plurality of laser beams, and the plurality of laser beams are emitted by the plurality of laser emitters respectively.

[0007] Optionally, the plurality of laser emitters are evenly arranged circumferentially on the mounting bracket, and the lasers emitted by the plurality of laser emitters intersect at the center of the field to be measured.

[0008] Optionally, the plurality of laser emitters are arranged at equal intervals, and the laser emission directions of the plurality of laser emitters are parallel to each other.

[0009] Optionally, the intersections formed by the lasers emitted by the plurality of laser emitters are evenly distributed throughout the area to be tested.

[0010] Optionally, the first laser controller and the second laser controller, under the control of the data processing module, send triangular wave electrical signals to the first laser and the second laser.

[0011] Optionally, the support structure includes several telescopic rods, each of which is driven by a motor to extend or retract.

[0012] Optionally, the support structure includes several L-shaped support rods and a telescopic rod. The mounting bracket is installed at one end of the several L-shaped support rods, and the other end of the several L-shaped support rods is fixed to one end of the telescopic rod. The telescopic rod is driven by a motor to achieve telescopic movement.

[0013] Optionally, the laser emitter is implemented using an optical fiber collimator.

[0014] The gas three-dimensional combustion temperature field measurement method based on the above system includes: adjusting the height of the support structure according to a preset first step length; each time the height is adjusted, calculating the average temperature of each laser propagation path in the area to be measured based on the data collected by the data acquisition card, and using the infrared thermal imager to obtain a temperature distribution map of the area to be measured, and determining the location of the high-temperature point by combining the temperature distribution map obtained by the infrared thermal imager; after the height of the support structure is adjusted, reconstructing the gas three-dimensional combustion temperature field based on the temperature and coordinates of each point at each height.

[0015] Optionally, the method further includes: deleting ghost points from the temperature distribution map obtained by the infrared thermal imager, and smoothing the data using spline interpolation to obtain a high-resolution two-dimensional temperature field distribution.

[0016] This application discloses a three-dimensional gas combustion temperature field measurement system and method based on thermal imaging and TDLAT. It uses an infrared thermal imager to capture a temperature distribution image of the area to be measured, and uses this image as a reference image. TDLAT technology is then used to measure the average temperature along each laser propagation path in the temperature field. The location of high-temperature points is determined by combining this with the reference image, thereby eliminating or avoiding the generation of "ghost points" and improving temperature measurement accuracy. Because this application uses an infrared thermal imager to determine the location of the actual high-temperature points, the operation is simple and does not involve iterative algorithms or machine vision technology, avoiding a large number of data processing steps and significantly improving measurement efficiency. The aforementioned system and method can achieve combustion diagnosis of marine diesel engines. By reconstructing the three-dimensional temperature distribution, the combustion state of marine diesel engines can be detected in real time. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the principle of TDLAS measurement in the background technology section;

[0018] Figure 2 This is a schematic diagram of the principle of a gas three-dimensional combustion temperature field measurement system based on a rotating optical path according to an embodiment of this application;

[0019] Figure 3 This is a schematic diagram of a mounting bracket according to an embodiment of this application;

[0020] Figure 4 This is a schematic diagram of a first arrangement of laser emitters and laser receivers according to an embodiment of this application. Some laser emitters and some laser receivers in the figure are not given reference numerals.

[0021] Figure 5This is a schematic diagram of a second arrangement of laser emitters and laser receivers according to an embodiment of this application. In the figure, straight arrows indicate the direction of laser propagation, and curved arrows indicate the direction of rotation of the mounting bracket. Some laser emitters and some laser receivers in the figure are not given reference numerals.

[0022] Figure 6 This is a schematic diagram of a third arrangement of laser emitters and laser receivers according to an embodiment of this application. In the figure, straight arrows indicate the direction of laser propagation, and curved arrows indicate the direction of rotation of the mounting bracket. Some laser emitters and some laser receivers in the figure are not given reference numerals.

[0023] Figure 7 This is a schematic diagram illustrating the principle of infrared thermal imaging detection according to an embodiment of this application;

[0024] Figure 8 This is a schematic diagram of the three-dimensional combustion temperature field of the reducing gas according to an embodiment of this application. Detailed Implementation

[0025] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0026] As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context indicates otherwise. It should be further understood that the terms “comprising,” “including,” indicate the presence of the stated feature, operation, element, component, item, kind, and / or group, but do not preclude the presence, occurrence, or addition of one or more other features, operations, elements, components, items, kinds, and / or groups. The terms “or” and “and / or” as used herein are interpreted as inclusive, or mean any one or any combination thereof. Thus, “A, B, or C” or “A, B, and / or C” means “any one of: A; B; C; A and B; A and C; B and C; A, B, and C.” Exceptions to this definition occur only when combinations of elements, functions, or operations are inherently mutually exclusive in some manner.

[0027] To address the problem that existing methods for reconstructing temperature fields using TDLAS technology have long data processing times when filtering "phantom points," which affects the speed of real-time online measurement, this invention provides a gas three-dimensional combustion temperature field measurement system and method based on a rotating optical path. This system can eliminate phantom points during the testing and measurement process, with low data processing volume and fast measurement speed.

[0028] Figure 2 This is a schematic diagram illustrating the principle of a gas three-dimensional combustion temperature field measurement system based on a rotating optical path, according to an embodiment of this application. Figure 2 As shown, the system includes a first laser controller 1, a second laser controller 2, a first laser 3, a second laser 4, a beam combiner 5, a beam splitter 6, several laser emitters 7, several laser receivers 8, a mounting bracket 9, a support structure 10 capable of extending and retracting in the vertical direction, an infrared thermal imager 11, a data acquisition card 12, and a data processing module 13. The data processing module 13 can be embedded in a computing device, which can be a computing device such as a computer. The mounting bracket 9 can be a hollow circle or polygon, and the central part of the area enclosed by the mounting bracket 9 is the area to be measured.

[0029] The position of one end of the support structure 10 is fixed, for example, fixed on the experimental table, while the other end of the support structure 10 can extend and retract in the vertical direction.

[0030] In one implementation, the support structure 10 includes a plurality of telescopic rods. Figure 2 For example, the mounting bracket 9 is circular, and the support structure 10 may consist of only three telescopic rods. These three rods are arranged vertically and evenly distributed on the mounting bracket 9. Each telescopic rod is driven by a motor, and the data processing module 13 sends the same control signal to the three motors to control them to simultaneously extend or shorten by the same length. In this implementation, the support structure 10 has a simple structure and low manufacturing cost.

[0031] In another implementation, the support structure 10 includes three L-shaped support rods and one telescopic rod, so as to... Figure 3 For example, the mounting bracket 9 is circular, and the three L-shaped support rods bend in the same direction. The mounting bracket 9 is installed at one end of the three L-shaped support rods, and the other ends of the three L-shaped support rods are fixed to one end of the telescopic rod. The telescopic rod is driven by only one motor. In this implementation, the height of the mounting bracket 9 is adjusted by a single motor. During the adjustment process, the problem of tilting of the mounting bracket 9 caused by inconsistent telescopic lengths of multiple motors can be avoided.

[0032] Both the laser emitter 7 and the laser receiver 8 are fixed on the mounting bracket 9, with each laser emitter 7 corresponding to a laser receiver 8. The arrangement of the laser emitters 7 must meet the following condition: the transmission path of the laser emitted from each laser emitter 7 must be evenly distributed across the area to be measured.

[0033] The data processing module 13 receives various parameters set by the user. These parameters may include, for example, the waveform, period, amplitude, duty cycle, etc., of the electrical signals output by the first laser controller 1 and the second laser controller 2. The waveform of the electrical signal may be, for example, a triangular wave. These parameters are applied to the first laser controller 1 and the second laser controller 2 through the data acquisition card 12. The first laser controller 1 and the second laser controller 2 output corresponding electrical signals according to the set parameters. The electrical signals output by the first laser controller 1 and the second laser controller 2 serve as the power supply for the first laser 3 and the second laser 4, respectively. The first laser 3 and the second laser 4 output lasers of different frequencies. After the two laser beams are combined by the beam combiner 5, they are then split into multiple laser beams by the beam splitter 6. Each laser beam enters a laser emitter 7 and is emitted from the laser emitter 7. The laser emitter 7 can be implemented using an optical fiber collimator. The central area of ​​the mounting bracket 9 is a flame field. The laser emitted by the laser emitter 7 is absorbed by the combustion products as it passes through the flame field. The absorbed light signal is received by the laser receiver 8, which converts the received light signal into an electrical signal. This electrical signal is acquired by the data acquisition card 12, which inputs the acquired electrical signal into the data processing module 13. The data processing module 13 performs calculations to obtain the temperature and position coordinates of each point on the laser propagation path.

[0034] There are several ways to arrange the laser transmitter 7 and the laser receiver 8.

[0035] In the first implementation, the mounting bracket 9 is circular, and the laser emitters 7 and laser receivers 8 are distributed alternately on the circumference of the mounting bracket 9. The laser emitters 7 are evenly spaced, and the light emission direction of the laser emitters 7 faces the center of the mounting bracket 9. Figure 4 As shown. The advantage of this implementation is that the laser distribution is relatively dense within the test area, which can improve measurement accuracy. However, the distance between the laser emitter 7 and the laser receiver 8 on the circumference of the mounting bracket 9 is relatively large, making installation and operation more convenient. The system structure is simple, the cost is low, and it is easy to carry out experiments. Furthermore, the circular mounting bracket 9 has better adaptability to various temperature fields than the rectangular mounting bracket 9.

[0036] In the second implementation, the mounting bracket 9 is circular or rectangular, and the laser emitters 7 are arranged at equal intervals on the mounting bracket 9, with the light emission directions of each laser emitter parallel to each other. For example... Figure 5 As shown. Figure 5 Taking a rectangular mounting bracket 9 as an example, the laser emitters 7 are arranged at equal intervals, and the laser emission directions are parallel to each other. The laser emitters 7 and laser receivers 8 can be arranged on two opposite sides of the mounting bracket 9, respectively. Compared with the first implementation, the advantage of this implementation is that the laser emitters 7 and laser receivers 8 are easier to position, the arrangement process is simpler and easier to operate, and it is convenient to carry out experiments.

[0037] In the third implementation, the lasers emitted by several laser emitters 7 form a series of intersections, which are evenly distributed across the area to be measured. Figure 6 For example, Figure 6 The mounting bracket 9 shown is rectangular, and the laser emitters 7 are divided into two groups. The laser emitters 7 within each group are equally spaced, with their laser emission directions parallel to each other. The laser emission directions of the two groups of laser emitters 7 are perpendicular to each other, and the lasers emitted by the two groups intersect each other, forming a grid. The two groups of laser emitters 7 and two groups of laser receivers 8 can be arranged on the four sides of the mounting bracket 9. Compared with the first implementation, this implementation is advantageous because the laser emitters 7 and laser receivers 8 are easier to position, the arrangement process is simpler and easier to operate, and it facilitates experiments. Compared with the second implementation, this implementation is advantageous because the location of high-temperature points (including ghost points) can be determined based on the data measured by the laser receivers 8. This location is then compared with the location of high-temperature points in the reference image captured by the infrared thermal imager. This eliminates ghost points and calibrates the location of high-temperature points, further improving the accuracy of the measurement results.

[0038] The principle of temperature detection by infrared thermal imager 11 is as follows: Figure 7 As shown. Objects at any temperature radiate energy outwards. Infrared thermal imaging technology follows Planck's law of radiation, receiving radiation generated by the object's surface, converting it into an electrical signal, processing the signal, and presenting the measurement result as a visible light image. The image is then sent to a host computer in real time, offering advantages such as intuitiveness, efficiency, wide applicability, non-contact operation, and high accuracy. Infrared thermal imagers can measure objects within many common temperature ranges, including the temperature of combustion flames. By measuring the temperature of combustion flames, energy conversion and transfer during combustion can be studied. In this embodiment, an infrared thermal imager 11 is used to measure the flame field, obtaining the temperature distribution of the flame field and surrounding area. This distribution serves as a benchmark to filter out ghost points in the high-temperature points measured by the TDLAT method.

[0039] The method for measuring the three-dimensional combustion temperature field of gas using the above system is as follows:

[0040] 1. Adjust the height of the support structure 10 according to the preset step length.

[0041] 2. Each time the height is adjusted, the average temperature of each laser propagation path in the test area is calculated based on the data collected by the data acquisition card 12, thereby obtaining the temperature of each point in the test area. The temperature distribution map of the test area obtained by the infrared thermal imager 11 is used as a reference to determine the location of high temperature points and filter out ghost points. Then, spline interpolation is used for smoothing to obtain a high-resolution two-dimensional temperature field distribution.

[0042] 3. Once the height of the supporting structure is adjusted, reconstruct the three-dimensional combustion temperature field of the gas based on the temperature and coordinates of each point at each height.

[0043] According to the Lambert-Beer law, when a laser beam with frequency ν and intensity I₀ passes through a gas cell with optical path length L, the gas molecules will selectively absorb light in a specific frequency band, causing the light intensity to attenuate to I₀. t Its transmitted light intensity I t It can be represented as:

[0044]

[0045] Where, k v The light absorption coefficient can be described by equation (2):

[0046] k v =S(T)·Φ(T,P,χ) i )·χ i ·P (2)

[0047] The above equation is the classic Beer-Lambert absorption theorem, which is the theoretical basis of the TDLAS test method. S(T) is the absorption line intensity. The absorption line intensity S(T0) at the reference temperature T0 is obtained from the HITRAN database, and then the line intensity S(T) at temperature T is calculated by equation (3).

[0048]

[0049] Where the subscript i represents the i-th spectral line; h is Planck's constant; c is the speed of light; k′ is Boltzmann's constant; ν0 is the transition frequency; v 0,i Let E' represent the transition frequency corresponding to the i-th spectral line; E″ is the energy of the low transition state; and Q is the total molecular partition function, which is usually obtained by polynomial fitting.

[0050] Direct absorption is one of the most commonly used gas detection methods, offering advantages such as simplicity and ease of implementation. Its measurement principle is based on the characteristics of semiconductor lasers. A signal generator and laser driver inject a sawtooth or sinusoidal current signal into the laser to control its output wavelength, enabling it to scan and cover the absorption peak of the gas to be detected. After the laser light is absorbed by the gas in the test field, a detector receives the attenuated light intensity signal, converts it into an electrical signal, inputs it into a data acquisition card, and finally transmits it to a computer for data processing. According to Lambert-Beer's law, by processing the light intensity before and after gas absorption, the temperature and concentration of the gas can be deduced.

[0051] As shown in equation (3), the line intensity S(T) of the spectral line is a single-parameter function of temperature T. The relationship between temperature T and the line intensity S(T) can be used to measure the gas temperature. The basic principle is based on the different amplitude changes in the line intensity of different spectral lines with temperature. Two relatively independent spectral lines are selected as the test objects, and the relative values ​​of their line intensities at different temperatures are calculated. The average temperature on the measured optical path is then inverted using the relative ratio of the line intensities of the two absorption spectral lines. The relative ratio R of the line intensities of the two absorption spectral lines can be expressed as:

[0052]

[0053] In this context, subscript 1 indicates the first spectral line, and subscript 2 indicates the second spectral line.

[0054] Integrating both sides of equation (1), we can obtain the expression for the integrated absorbance A, i.e., the area covered by the absorption spectral line:

[0055]

[0056] Where P is the total gas pressure, χi is the mole fraction of the absorbed gas, and f(vv) o ) is the line shape function of the absorption spectral line.

[0057] It is easy to see that when using the direct absorption method for temperature measurement, the gas concentration and ambient pressure do not affect the accuracy of the test results. The temperature can be obtained from the following formula:

[0058]

[0059] The temperature calculated by equation (6) is the average temperature of the propagation path of a laser beam. When two beams intersect, the average temperature of the propagation path of each laser beam is calculated, and the average of the two average temperatures is taken as the temperature at the intersection point of the two laser beams. Based on the propagation directions of the two laser beams and the position of the laser emitter 7, the coordinates of the intersection point of the two laser beams can be calculated.

[0060] Based on the above principles, Figures 4 to 6 The following methods were used to measure the temperature in each of the proposed schemes.

[0061] In one implementation, the laser emitter 7 is arranged as follows: Figure 4 or Figure 5 As shown. When the mounting bracket 9 is adjusted to a certain height, the average temperature of each laser transmission path is calculated based on the data collected by the data acquisition card 12. This average temperature value is then used as the temperature value of all points on the corresponding laser transmission path. For example, if the average temperature of the transmission path of a laser emitted by a certain laser emitter 7 is calculated to be T, then the temperature of any point on that transmission path is considered to be T. Assuming there are two high-temperature points A and B in the area to be measured, and a laser beam passes through high-temperature point A, the transmission path of this laser is denoted as l. A Another laser beam passes through the high-temperature point B, and the transmission path of this laser beam is denoted as l. B After calculation, path l is obtained. A The average temperature is T A Path l B The average temperature is T B Based on the images captured by the infrared thermal imager 11, the specific locations of high-temperature points A and B can be determined. Thus, the locations and temperatures of high-temperature points A and B can be obtained. Combined with the average temperature along other laser beam transmission paths, the two-dimensional temperature distribution of the area to be measured at the current height of the mounting bracket 9 can be obtained. Using the same method to obtain the two-dimensional temperature distribution of the area to be measured at each height of the mounting bracket 9, the three-dimensional temperature distribution of the area to be measured can be obtained, such as... Figure 8 As shown in the figure. This implementation method can avoid the occurrence of ghost points without using complex calculations such as convolutional neural network iterative algorithms or machine vision to eliminate ghost points. The calculation process is short and has strong real-time performance.

[0062] In another implementation, the laser emitter 7 is arranged as follows: Figure 6As shown. When the mounting bracket 9 is adjusted to a certain height, the average temperature of each laser transmission path is calculated based on the data collected by the data acquisition card 12. This average temperature value is used as the temperature value of all points on the corresponding laser transmission path. For example, if there are two high-temperature points A and B in the area to be measured, and l1, l2, l3, and l4 represent the propagation paths of four laser beams respectively, where l1 and l3 intersect at point A, l2 and l3 intersect at point B, l1 and l4 intersect at point C, and l2 and l4 intersect at point D, then the calculation result will show four high-temperature points A, B, C, and D. C and D are the ghost points. However, the high-temperature points presented in the image captured by the infrared thermal imager 11 are the real high-temperature points. Therefore, the image captured by the infrared thermal imager 11 only contains two high-temperature points, A and B. Based on this, C and D can be determined as ghost points and eliminated. The coordinates of A and B are calculated based on the three straight lines l1, l2, and l3. Thus, the temperature and position of all high-temperature points in the area to be measured can be obtained. The temperature at other locations within the measurement area can be obtained using the same method. A two-dimensional temperature distribution map is plotted based on the temperature and location of each point in the measurement area at the current height of the mounting bracket 9. The three-dimensional temperature distribution of the measurement area at each height of the mounting bracket 9 is obtained using the same method, thus yielding the three-dimensional temperature distribution of the measurement area. This implementation uses images captured by the infrared thermal imager 11 to determine ghost points, eliminating the need for complex calculations such as convolutional neural network iterative algorithms or machine vision to eliminate ghost points. The calculation process is short and highly real-time. Furthermore, the location of high-temperature points can be calculated either through the laser transmission path or through images captured by the infrared thermal imager 11; these two methods can be mutually corrected to improve measurement accuracy.

[0063] The data processing module 13 of this embodiment can be implemented in conjunction with hardware or software, or a combination thereof. Thus, the method and apparatus of the present invention, or certain aspects or portions thereof, can take the form of program code (i.e., instructions) embedded in a tangible medium, such as a removable hard disk, USB flash drive, floppy disk, CD-ROM, or any other machine-readable storage medium, wherein when the program is loaded into a machine such as a computer and executed by said machine, said machine becomes an apparatus for practicing the present invention.

Claims

1. A gas three-dimensional combustion temperature field measurement system based on thermal imaging and TDLAT, characterized in that, include: The system comprises a first laser controller, a second laser controller, a first laser, a second laser, a beam combiner, a beam splitter, several laser emitters, several laser receivers, a mounting bracket, a support structure capable of extending and retracting in the vertical direction, an infrared thermal imager, a data acquisition card, and a data processing module. The mounting bracket is fixed to the top of the support structure, and the area to be measured is located within the area enclosed by the mounting bracket; The infrared thermal imager is used to image the area to be measured; The plurality of laser emitters are arranged on the mounting bracket, and the laser emitted by the plurality of laser emitters is located in the plane of the mounting bracket, and the propagation path of the laser emitted by the plurality of laser emitters is evenly distributed throughout the area to be tested. The plurality of laser receivers are arranged on the mounting bracket, and the plurality of laser emitters and the plurality of laser receivers correspond one-to-one; The data processing module sends control signals to the first laser controller and the second laser controller through the data acquisition card, and receives data acquired by the plurality of laser receivers; The first laser controller and the second laser controller control the first laser and the second laser respectively according to the received control signals; The lasers of different frequencies output by the first laser and the second laser sequentially enter the beam combiner and the beam splitter and are divided into several laser beams, which are then emitted by the several laser emitters.

2. The system as described in claim 1, characterized in that, The plurality of laser emitters are evenly arranged circumferentially on the mounting bracket, and the lasers emitted by the plurality of laser emitters intersect at the center of the field to be measured.

3. The system as described in claim 1, characterized in that, The plurality of laser emitters are arranged at equal intervals, and the laser emission directions of the plurality of laser emitters are parallel to each other.

4. The system as described in claim 1, characterized in that, The intersections formed by the lasers emitted by the plurality of laser emitters are evenly distributed throughout the area to be tested.

5. The system as described in any one of claims 2 to 4, characterized in that, Under the control of the data processing module, the first laser controller and the second laser controller send triangular wave electrical signals to the first laser and the second laser, respectively.

6. The system as described in claim 1, characterized in that, The support structure includes several telescopic rods, each of which is driven by a motor to extend or retract.

7. The system as described in claim 1, characterized in that, The support structure includes several L-shaped support rods and a telescopic rod. The mounting bracket is installed at one end of the several L-shaped support rods, and the other end of the several L-shaped support rods is fixed to one end of the telescopic rod. The telescopic rod is driven by a motor to achieve telescopic movement.

8. The system as described in claim 1, characterized in that, The laser emitter is implemented using an optical fiber collimator.

9. A method for measuring the three-dimensional combustion temperature field of a gas based on the system according to any one of claims 1-8, characterized in that, include: Adjust the height of the support structure according to the preset first step length; Each time the height is adjusted, the average temperature of each laser propagation path in the area to be tested is calculated based on the data collected by the data acquisition card. The temperature distribution map of the area to be tested is obtained using the infrared thermal imager, and the location of the high temperature point is determined by combining the temperature distribution map obtained by the infrared thermal imager. Once the height of the supporting structure is adjusted, the three-dimensional combustion temperature field of the gas is reconstructed based on the temperature and coordinates of each point at each height.

10. The method for measuring the three-dimensional combustion temperature field of a gas as described in claim 9, characterized in that, Also includes: By combining the temperature distribution map obtained by the infrared thermal imager, ghost points are removed, and spline interpolation is used for smoothing to obtain a high-resolution two-dimensional temperature field distribution.

Images