Combustion field three-dimensional temperature, concentration and particle information inversion method and system based on visible light and infrared light field cameras

Abstract

The invention discloses a combustion field three-dimensional temperature, concentration and particle information inversion method and system based on visible light and infrared light field cameras, and belongs to the technical field of flame combustion detection. The problem that an existing combustion field diagnosis technology is poor in precision of three-dimensional and multi-parameter diagnosis of a complex combustion field is solved. A visible light field camera and an infrared light field camera are adopted to collect radiation light field image signals of flame, and a visible light field measurement signal and an infrared light field measurement signal are obtained; the gray value of the flame field image is extracted, and then a radiation intensity distribution diagram of the flame is obtained; establishing a radiation transfer equation, obtaining a three-dimensional space of a combustion field, and obtaining a radiation source item under each wavelength in combination with a Tikhonov regularization algorithm; solving the black particle temperature, the absorption coefficient and the absorption coefficient of the to-be-detected gas by utilizing the obtained radiation source item and the absorption peak wavelength of the to-be-detected gas; finally, the smoke black particle concentration and the to-be-detected gas concentration are obtained through inversion. The method is suitable for the technical field of flame combustion detection.

Description

Technical Field

[0001] The invention belongs to the technical field of flame combustion detection. Background Art

[0002] In the fields of aerospace, energy and power, steel and metallurgy, and chemical engineering, high-temperature combustion is a common phenomenon in equipment such as rocket engines, gas turbines, internal combustion engines, power plant boilers, and coal gasification reactors. The efficient operation and safety of these devices depend on the precise monitoring of the combustion state.

[0003] Key physical quantities such as the flame's temperature field, gas product concentrations (such as CO2, H2O, CO), and soot particle concentration directly reflect the combustion state and characterize the chemical reaction rate and pollutant emission levels within the flame. However, the physical properties of the translucent medium within the flame significantly affect the accuracy of temperature field detection. These physical properties are not only functions of the spectrum and temperature but are also closely related to multiple physical fields such as concentration and pressure. Furthermore, the transient pulsating characteristics of the flame caused by multiphase flow and high-temperature chemical reactions cause the temperature field, physical property field, and concentration field to exhibit strong dynamic changes. Therefore, while monitoring the flame temperature field, it is necessary to conduct online coordinated measurement of these multiple physical fields, including temperature, physical property, and concentration fields, to comprehensively evaluate combustion performance and ensure safe equipment operation. This coordinated measurement of multiple physical fields is crucial for improving combustion efficiency, reducing pollutant emissions, and ensuring equipment safety.

[0004] Traditional combustion field diagnostic techniques can only measure single parameters or two-dimensional surfaces, making them difficult to meet the needs of three-dimensional, multi-parameter diagnostics for complex combustion fields. Light field cameras, as a new imaging technology, can simultaneously capture both light intensity and light field direction information, providing new possibilities for three-dimensional inversion of combustion fields. Summary of the Invention

[0005] The present invention aims to solve the problem of poor accuracy of existing combustion field diagnosis technology in three-dimensional, multi-parameter diagnosis of complex combustion fields. It now provides a method and system for inverting three-dimensional temperature, concentration and particle information of the combustion field based on visible light and infrared light field cameras.

[0006] The method for inverting three-dimensional temperature, concentration, and particle information of a combustion field based on visible light and infrared light field cameras of the present invention includes:

[0007] Step 1: Use visible light field camera and infrared light field camera to collect the radiation light field image signal of the flame to obtain the visible light field measurement signal I K and infrared light field measurement signal I H ;

[0008] Step 2: Using the blackbody radiation law, measure the visible light field signal IK and infrared light field measurement signal I H The flame blackbody radiation intensity is obtained by calibrating the blackbody furnace and measuring the signal I from the visible light field. K and infrared light field measurement signal I H , extract the gray value of the flame field image, calibrate the flame blackbody radiation intensity with the gray value of the flame field image, and obtain the flame radiation intensity distribution diagram I λ ;

[0009] Step 3: Use the flame radiation intensity distribution diagram I λ , establish the radiation transfer equation, obtain the three-dimensional space of the combustion field, discretize the three-dimensional space of the combustion field into N cubic elements, construct the radiation energy equation group, and combine the Tikhonov regularization algorithm to obtain the radiation source term H at each wavelength λ ;

[0010] Step 4: Use the radiation source term H λ and the absorption peak wavelength of the gas to be measured, and solve to obtain the black particle temperature, absorption coefficient and absorption coefficient of the gas to be measured; and use the soot particle temperature to obtain the three-dimensional temperature field of the flame;

[0011] Step 5: Use Mie theory and soot particle absorption coefficient to invert and calculate the soot particle concentration;

[0012] Step 6: Use the statistical narrow-band method to invert the concentration of the gas to be measured based on the gas absorption coefficient.

[0013] Furthermore, in the present invention, in step 2, the radiation intensity distribution diagram of the flame I λ The method is:

[0014] Using the blackbody radiation law, the flame monochromatic radiation intensity is obtained:

[0015]

[0016] h is Planck's constant, c is the speed of light, λ is the wavelength, k is the Boltzmann constant, T is the absolute temperature of the blackbody furnace, I b,λ is the blackbody radiation intensity, extract the visible light field measurement signal I K and infrared light field measurement signal I H According to the one-to-one correspondence between the blackbody radiation intensity and the grayscale value of the flame image, the grayscale value and the blackbody radiation intensity are marked to obtain the flame radiation intensity distribution diagram I λ .

[0017] Furthermore, in the present invention, in step 3, the radiation transfer equation is:

[0018]

[0019] Where dω is the incident solid angle, k ext,λ is the attenuation coefficient of the medium in the microelement at wavelength λ, k abs,λ is the absorption coefficient of the medium in the microelement at wavelength λ, I b,λ (T) is the blackbody radiation intensity at wavelength λ, k sca,λ is the scattering coefficient of the medium in the microelement at wavelength λ, is the intensity of monochromatic radiation from the outside into the microelement in the direction of S' when the wavelength is λ, yes The flame radiates light from the direction of the incident Scattering phase function for directional scattering.

[0020] Furthermore, in the present invention, in step 3, the method for discretizing the three-dimensional space of the combustion field into N cubic elements is:

[0021] According to the properties of the combustion field, the radiation transfer equation is simplified to obtain the three-dimensional space of the combustion field, and then the three-dimensional space of the combustion field is discretized into N cubic elements:

[0022]

[0023] Where, I λ (x) is the monochromatic radiation intensity of ray x reaching the light field camera, κ λ (s) is the local absorption coefficient, I b,λ (s) is the local monochromatic blackbody radiation intensity, H λ (s) is the local radiation source term, κ λ (n) is the absorption coefficient of volume element n, H λ (n) is the radiation source term of volume element n, lx(n) is the ray length of ray x in volume element n, where

[0024] H λ (n) = κ λ (n)I b,λ (n) Formula 4

[0025] I b,λ (s) is the monochromatic blackbody radiation intensity of volume element n, which is calculated according to Wien's law:

[0026]

[0027] T n is the temperature of element n, c1 is the first radiation constant, and c2 is the second radiation constant.

[0028] Furthermore, in the present invention, in step 3, the radiation energy equations are:

[0029]

[0030] Where X is the total number of discrete directions in three-dimensional space, X is the total number of discrete directions in three-dimensional space, and x = 1, 2, ..., X.

[0031] Furthermore, in the present invention, in step 3, the radiation source term H at each wavelength is obtained. λ The method is:

[0032] Convert the radiation energy equations into matrix equation form:

[0033] I λ =[I λ (1)……I λ (x)……I λ Formula 7

[0034] Convert to a matrix equation:

[0035] I λ =A·H λ Formula 8

[0036] Where A is the ray length matrix of X-rays in each voxel; I λ is the monochromatic radiation intensity matrix of the X-rays reaching the light field camera;

[0037] The matrix equation is solved using the Tikhonov regularization algorithm to obtain the radiation source term H at each wavelength. λ ;

[0038] H λ =(A T A+αL T L) -1 A T I λ Formula 9

[0039] Where α is the regularization parameter, L is the regularization function, and the monochromatic radiation intensity matrix I λ Obtained through regularization solution.

[0040] Furthermore, in the present invention, in step 4, the radiation source term H is obtained by λ The matrix equation of the gas absorption peak wavelength is used to solve the soot particle temperature, soot particle absorption coefficient and the absorption coefficient of the gas to be measured as follows:

[0041] In the band without gas absorption peak, let the monochromatic absorption coefficient of the flame be equal to the absorption coefficient of the soot particles:

[0042] k λ =κ p,λ Formula 10

[0043] κp,λ The calculation equations for the soot absorption coefficient, particle temperature, and absorption coefficient are:

[0044]

[0045] In the wavelength band containing the absorption peak of the gas to be measured, the monochromatic absorption coefficient of the flame is composed of the absorption coefficients of the soot particles and the gas to be measured:

[0046] κ λ =κ p,λ +κ g,λ Formula 12

[0047] The calculation equation using the soot particle temperature, absorption coefficient and absorption coefficient of the gas to be measured is:

[0048]

[0049] The soot particle temperature, soot particle absorption coefficient and the absorption coefficient of the gas to be measured are obtained by numerically solving equations at multiple wavelengths.

[0050] Furthermore, in the present invention, in step 5, the method for inverting the soot particle concentration using Mie theory and the soot particle absorption coefficient is:

[0051] The soot absorption coefficient calculation formula is used to calculate the radiation source term at a wavelength without gas absorption, and then the soot particle temperature and particle concentration are calculated by solving the overdetermined equation:

[0052] Among them, the calculation formula of the absorption coefficient of soot is:

[0053]

[0054] Where, κ p,λ is the absorption coefficient of soot particles, f v is the soot particle concentration, E(m) is the function of the complex refractive index of the soot particles that varies with wavelength, λ is the wavelength in micrometers, n is the refractive index, k is the absorption factor, and f v is the concentration of soot particles;

[0055] The radiation source term at the wavelength without gas absorption is:

[0056]

[0057] Arranged:

[0058]

[0059] Where c1 is the first radiation constant, c2 is the second radiation constant;

[0060] The temperature and concentration of soot particles are obtained by calculating Formula 16 using the method of solving overdetermined equations.

[0061] Furthermore, in the present invention, in step 6, the method for inverting and calculating the concentration of the gas to be measured based on the gas absorption coefficient using the statistical narrow-band method is:

[0062] The concentration of the gas to be measured is calculated using the radiation source term calculation formula at a wavelength containing the absorption effect of the gas to be measured combined with the statistical narrowband method;

[0063] The calculation formula for the radiation source term at a wavelength that includes gas absorption is:

[0064]

[0065] Arranged:

[0066]

[0067] Specific calculation formula of statistical narrow-band method:

[0068] κ g,λ =exp(-W) Formula 19

[0069] Where W is the optical thickness, and the spectral line intensity in the narrow band is set to an inverse exponential distribution, and the concentration of the gas to be measured is calculated as:

[0070]

[0071] Where, Y is the length of the path traveled by the light, f g is the concentration of the radiative gas, P represents the total gas pressure, represents the ratio of the average line width to the spacing, is the average line width, and is the average spacing between spectral lines, is the average absorption coefficient.

[0072] A combustion field three-dimensional temperature, concentration and particle information inversion system based on the above method includes: a visible light field camera, an infrared light field camera, a synchronous controller and a data processing system;

[0073] The visible light field camera and the infrared light field camera are relatively arranged on both sides of the flame to be measured, and filters are added to the visible light field camera and the infrared light field camera;

[0074] The visible light field camera and the infrared light field camera simultaneously collect light field information through a synchronous controller; and send the collected signals to the data processing system respectively;

[0075] The data processing system uses the received light field information in combination with the radiation transfer equation and the absorption peak wavelength of the gas to be measured to solve the soot particle temperature, absorption coefficient, absorption coefficient of the gas to be measured and the three-dimensional temperature field of the flame; and combines Mie theory and statistical narrowband method to invert the soot particle concentration and the gas concentration to be measured.

[0076] Furthermore, in the present invention, filters of different wavelength bands are provided on the visible light field camera and the infrared light field camera according to the different wavelengths of the gas to be measured.

[0077] Furthermore, the present invention also includes a plurality of visible light field cameras and infrared light field cameras, which are interspersed and arranged at intervals around the flame field. Each visible light field camera 1 is arranged opposite to an infrared light field camera, and the distance between any two adjacent cameras is equal.

[0078] The present invention is based on a real-time monitoring and diagnostic system of visible light and infrared light field cameras, which realizes the synchronous inversion of temperature, concentration and particle information, breaking through the limitations of traditional single parameter measurement, providing support for the optimization of the combustion process, and significantly improving the efficiency of combustion diagnosis. At the same time, the non-invasive measurement based on visible light and infrared light field cameras avoids the interference of the probe on the flow field, ensuring the authenticity and reliability of the measurement results. The introduction of filters or spectrometers in the infrared light field camera realizes the multi-component spectral separation and measurement of different gases produced by combustion, thereby improving the accuracy of component concentration inversion. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Figure 1 A flow chart of the method of the present invention;

[0080] Figure 2 This is a schematic diagram of the system of the present invention;

[0081] Figure 3 This is a block diagram of the principle of using multiple infrared light field cameras and visible light field cameras to collect signals;

[0082] Figure 4 FIG. 1 is a schematic diagram of the installation of a narrowband filter in a specific embodiment. DETAILED DESCRIPTION

[0083] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other in the absence of conflict.

[0084] Specific implementation method 1: refer to Figure 1 Specifically describing this embodiment, the method for inverting three-dimensional temperature, concentration, and particle information of a combustion field based on visible light and infrared light field cameras described in this embodiment includes:

[0085] Step 1: Use a visible light field camera and an infrared light field camera to collect the radiation light field image signal of the flame, and add filters to the visible light field camera and the infrared light field camera according to the components to be collected; obtain the corresponding visible light field measurement signal I K and infrared light field measurement signal I H ;

[0086] Step 2: Using the blackbody radiation law, measure the visible light field signal I K and infrared light field measurement signal I H The flame blackbody radiation intensity is obtained by calibrating the blackbody furnace and measuring the signal I from the visible light field. K and infrared light field measurement signal I H , extract the gray value of the flame field image, calibrate the flame blackbody radiation intensity with the gray value of the flame field image, and obtain the flame radiation intensity distribution diagram I λ ;

[0087] Step 3: Use the flame radiation intensity distribution diagram I λ , establish the radiation transfer equation, obtain the three-dimensional space of the combustion field, discretize the three-dimensional space of the combustion field into N cubic elements, construct the radiation energy equation group, and combine the Tikhonov regularization algorithm to obtain the radiation source term H at each wavelength λ ;

[0088] Step 4: Use the radiation source term H λ and the absorption peak wavelength of the gas to be measured, and solve to obtain the black particle temperature, absorption coefficient and absorption coefficient of the gas to be measured; and use the soot particle temperature to obtain the three-dimensional temperature field of the flame;

[0089] Step 5: Use Mie theory and soot particle absorption coefficient to invert and calculate the soot particle concentration;

[0090] Step 6: Use the statistical narrow-band method to invert the concentration of the gas to be measured based on the gas absorption coefficient.

[0091] Furthermore, in the present invention, in step 2, the radiation intensity distribution diagram of the flame I λ The method is:

[0092] Using the blackbody radiation law, the flame monochromatic radiation intensity is obtained:

[0093]

[0094] h is Planck's constant, c is the speed of light, λ is the wavelength, k is the Boltzmann constant, T is the absolute temperature of the blackbody furnace, I b,λ is the blackbody radiation intensity, extract the visible light field measurement signal I K and infrared light field measurement signal I H According to the one-to-one correspondence between the blackbody radiation intensity and the grayscale value of the flame image, the grayscale value and the blackbody radiation intensity are marked to obtain the flame radiation intensity distribution diagram I λ ;

[0095] Furthermore, in the present invention, in step 3, the radiation transfer equation is:

[0096]

[0097] Where dω is the incident solid angle, k ext,λ is the attenuation coefficient of the medium in the microelement at wavelength λ, k abs,λ is the absorption coefficient of the medium in the microelement at wavelength λ, I b,λ (T) is the blackbody radiation intensity at wavelength λ, k sca,λ is the scattering coefficient of the medium in the microelement at wavelength λ, is the intensity of monochromatic radiation from the outside into the microelement in the direction of S' when the wavelength is λ, yes The flame radiates light from the direction of the incident Scattering phase function for directional scattering.

[0098] Furthermore, in the present invention, in step 3, the method for discretizing the three-dimensional space of the combustion field into N cubic elements is:

[0099] According to the properties of the combustion field, the radiation transfer equation is simplified to obtain the three-dimensional space of the combustion field, and then the three-dimensional space of the combustion field is discretized into N cubic elements:

[0100]

[0101] Where, I λ (x) is the monochromatic radiation intensity of ray x reaching the light field camera, κ λ (n) is the local absorption coefficient, I b,λ (s) is the local monochromatic blackbody radiation intensity, H λ (n) is the local radiation source term, κ λ (n) is the absorption coefficient of volume element n, H λ (n) is the radiation source term of volume element n, lx(n) is the ray length of ray x in volume element n, where

[0102] H λ (n) = κ λ (n)Ib,λ (n) Formula 4

[0103] I b,λ (n) is the monochromatic blackbody radiation intensity of volume element n, which is calculated according to Wien's law:

[0104]

[0105] T n is the temperature of element n, c1 is the first radiation constant, and c2 is the second radiation constant.

[0106] Furthermore, in the present invention, in step 3, the radiation energy equations are:

[0107]

[0108] Where X is the total number of discrete directions in three-dimensional space, X is the total number of discrete directions in three-dimensional space, and x = 1, 2, ..., X.

[0109] Furthermore, in the present invention, in step 3, the radiation source term H at each wavelength is obtained. λ The method is:

[0110] Convert the radiation energy equations into matrix equation form:

[0111] I λ =[I λ (1)……I λ (x)……I λ (X)]Formula 7

[0112] Convert to a matrix equation:

[0113] I λ =A·H λ Formula 8

[0114] Where A is the ray length matrix of X-rays in each voxel; I λ is the monochromatic radiation intensity matrix of the X-rays reaching the light field camera;

[0115] The matrix equation is solved using the Tikhonov regularization algorithm to obtain the radiation source term H at each wavelength. λ ;

[0116] H λ =(A T A+αL T L) -1 A T I λ In formula 9, α is the regularization parameter, L is the regularization function, and the monochromatic radiation intensity matrix I λ Obtained through regularization solution.

[0117] Furthermore, in the present invention, in step 4, the radiation source term H is obtained by λ The matrix equation of the gas absorption peak wavelength is used to solve the soot particle temperature, soot particle absorption coefficient and the absorption coefficient of the gas to be measured as follows:

[0118] In the band without gas absorption peak, let the monochromatic absorption coefficient of the flame be equal to the absorption coefficient of the soot particles:

[0119] κ λ =κ p,λ Formula 10

[0120] κ p,λ The calculation equations for the soot absorption coefficient, particle temperature, and absorption coefficient are:

[0121]

[0122] In the wavelength band containing the absorption peak of the gas to be measured, the monochromatic absorption coefficient of the flame is composed of the absorption coefficients of the soot particles and the gas to be measured:

[0123] κ λ =κ p,λ +κ g,λ Formula 12

[0124] The calculation equation using the soot particle temperature, absorption coefficient and absorption coefficient of the gas to be measured is:

[0125]

[0126] The soot particle temperature, soot particle absorption coefficient and the absorption coefficient of the gas to be measured are obtained by numerically solving equations at multiple wavelengths.

[0127] Furthermore, in the present invention, in step 5, the method for inverting the soot particle concentration using Mie theory and the soot particle absorption coefficient is:

[0128] The soot absorption coefficient calculation formula is used to calculate the radiation source term at a wavelength without gas absorption, and then the soot particle temperature and particle concentration are calculated by solving the overdetermined equation:

[0129] Among them, the calculation formula of the absorption coefficient of soot is:

[0130]

[0131] Where, κ p,λ is the absorption coefficient of soot particles, f v is the soot particle concentration, E(m) is the function of the complex refractive index of the soot particles that varies with wavelength, λ is the wavelength in micrometers, n is the refractive index, k is the absorption factor, and fv is the concentration of soot particles;

[0132] The radiation source term at the wavelength without gas absorption is:

[0133]

[0134] Arranged:

[0135]

[0136] Where c1 is the first radiation constant, c2 is the second radiation constant;

[0137] The temperature and concentration of soot particles are obtained by calculating Formula 16 using the method of solving overdetermined equations.

[0138] Furthermore, in the present invention, in step 6, the method for inverting and calculating the concentration of the gas to be measured based on the gas absorption coefficient using the statistical narrow-band method is:

[0139] The concentration of the gas to be measured is calculated using the radiation source term calculation formula at a wavelength containing the absorption effect of the gas to be measured combined with the statistical narrowband method;

[0140] The calculation formula for the radiation source term at a wavelength that includes gas absorption is:

[0141]

[0142] Arranged:

[0143]

[0144] Specific calculation formula of statistical narrow-band method:

[0145] κ g,λ =exp(-W) Formula 19

[0146] Where W is the optical thickness, and the spectral line intensity in the narrow band is set to an inverse exponential distribution, and the concentration of the gas to be measured is calculated as:

[0147]

[0148] Where, Y is the length of the path traveled by the light, f g is the concentration of the radiative gas, P represents the total gas pressure, represents the ratio of the average line width to the spacing, is the average line width, and is the average spacing between spectral lines, is the average absorption coefficient.

[0149] Specific implementation method 2: Combination Figure 2-Figure 4This embodiment is described. This embodiment is a combustion field three-dimensional temperature, concentration and particle information inversion system based on the method described in the first embodiment, including: a visible light field camera 1, an infrared light field camera 2, a synchronous controller 3 and a data processing system 4;

[0150] The visible light field camera 1 and the infrared light field camera 2 are relatively arranged on both sides of the flame to be measured, and filters are added to the visible light field camera 1 and the infrared light field camera 2;

[0151] The visible light field camera 1 and the infrared light field camera 2 simultaneously collect light field information through the synchronization controller 3; and send the collected signals to the data processing system 4 respectively;

[0152] The data processing system 4 uses the received light field information in combination with the radiation transfer equation and the absorption peak wavelength of the gas to be measured to solve the soot particle temperature, absorption coefficient and absorption coefficient of the gas to be measured and the three-dimensional temperature field of the flame; and combines Mie theory and statistical narrowband method to invert the soot particle concentration and the gas concentration to be measured.

[0153] Furthermore, in this embodiment, during specific implementation, the filters set on the visible light field camera 1 are a blue light band filter and a red light band filter; a filter with a wavelength of 1870nm (containing the H2O absorption peak band) is set on the infrared light field camera to measure the concentration of water vapor in the combustion products of the water vapor flame field.

[0154] Furthermore, in this embodiment, a plurality of visible light field cameras 1 and infrared light field cameras 2 are also included, and the plurality of visible light field cameras 1 and infrared light field cameras 2 are interspersed and arranged around the flame field. Each visible light field camera 1 is arranged opposite to an infrared light field camera 2, and the distance between any two adjacent cameras is equal.

[0155] like Figure 2 As shown, the present invention provides a single light field camera inversion system device for three-dimensional temperature, concentration and particle information of a combustion field based on a visible light and infrared light field camera 2. When the device is used to collect light field information:

[0156] The visible light field camera 1 and the infrared light field camera 2 are installed in the combustion field at 180° positions to ensure that the entire combustion field is covered. The output end of the radiation light field image signal is connected to the data processing system 4. The visible light field camera 1 and the infrared light field camera 2 are both set through the sensor bracket 5.

[0157] Install two narrowband filters (450nm blue light band and 700nm red light band) in front of the main lens of visible light field camera 1, as shown in the following figure: Figure 4As described above, by covering the characteristic wavelengths of particle radiation respectively, the visible light field camera 1 can simultaneously collect image signals at two wavelengths; adding an 1870nm (containing the H2O absorption peak band) filter to the infrared light field camera 2 can separate the gas absorption characteristic band and capture the image signal of the gas absorption characteristic band.

[0158] Step 1: Start the synchronization controller 3 and set the dual cameras to synchronously acquire data at a high frame rate to avoid motion blur and capture the transient combustion process.

[0159] Step 2: Obtain the radiation light field image signal of the flame collected by the visible light field camera 1 and the infrared light field camera 2, obtain the visible light field measurement signals I1 and I2, and the infrared light field measurement signal I3 (where I3 is the characteristic absorption band of H2O), and transmit the signal to the data processing system 4;

[0160] Step 3: The measured light field signals I1, I2 and I3 are the grayscale image distribution of the flame, which are calibrated and processed by the data processing system 4 to obtain I λ1 , I λ2 and I λ3 , that is, the radiation intensity distribution of the flame;

[0161] Step 4: Discretize the three-dimensional space of the combustion field into N cubic elements, and use the radiation transfer equation to construct the radiation source term H λ The matrix equation of

[0162] The radiation transfer equation that takes into account the absorption, emission and scattering effects of the medium is as follows:

[0163]

[0164] Where dω is the incident solid angle, k ext,λ is the attenuation coefficient of the medium in the microelement at wavelength λ, k abs,λ is the absorption coefficient of the medium in the microelement at wavelength λ, I b,λ (T) is the blackbody radiation intensity at wavelength λ, k sca,λ is the scattering coefficient of the medium in the microelement at wavelength λ, is the intensity of monochromatic radiation from the outside into the microelement in the direction of S' when the wavelength is λ, yes The flame radiates light in the direction of the incident, Directional scattering is the scattering phase function;

[0165] Applying this solution model to hydrocarbon flames, the background radiation, self-absorption and scattering effects of particles in the hydrocarbon flames can be ignored, that is, the above radiation energy equation can be simplified to:

[0166]

[0167] Where, I λ (x) is the monochromatic radiation intensity of ray x reaching the light field camera, κ λ (n) is the local absorption coefficient, I b,λ (s) is the local monochromatic blackbody radiation intensity, H λ (s) is the local radiation source term, κ λ (n) is the absorption coefficient of volume element n, H λ (n) is the radiation source term of volume element n. x (n) is the ray length of ray x in voxel n, which is calculated by the inverse Monte Carlo algorithm based on the environmental conditions.

[0168] H λ (n) = κ λ (n)I b,λ (n)

[0169] I b,λ (n) is the monochromatic blackbody radiation intensity of volume element n, which can be calculated according to Wien's law:

[0170]

[0171] Assuming the total number of discrete directions in three-dimensional space is X, the above radiation energy equation can be transformed into the following system of equations:

[0172]

[0173] The above formula is converted into matrix equation form:

[0174] I λ =A·H λ

[0175] Where A is the ray length matrix of the X-rays in each voxel.

[0176] The matrix equation is solved using the Tikhonov regularization algorithm to obtain the radiation source term H at each wavelength λ .

[0177] Using the Tikhonov regularization algorithm, the above matrix equation can be expressed as:

[0178] H λ =(A T A+sL T L) -1 A T I λ

[0179] Where s is the regularization parameter and L is the regularization calculation process, usually In.

[0180] In the 450nm blue light band and the 700nm red light band, only the radiation from the particles is effective, and the H2O radiation is negligible. In the 1870nm band, which contains the H2O absorption peak, the radiation effect is caused by both the particles and H2O.

[0181] Therefore, in the calculation process, according to the image data I of the visible light field camera 1 λ1 and I λ2 The obtained H λ There is only particle absorption effect, according to the image data I of infrared light field camera 2 λ3 The obtained H λ There are particle absorption and H2O absorption.

[0182] Step 5: Use the radiation source term H at each wavelength λ , according to whether the measurement band contains the gas absorption peak, the particle temperature, particle absorption coefficient and gas absorption coefficient are solved.

[0183] Since solid particles and gases have different selectivity for wavelengths, the spectral curves of the particle absorption coefficient and the gas absorption coefficient can be separated.

[0184] In the band without gas absorption peak, the monochromatic absorption coefficient of the flame is equal to the particle absorption coefficient, that is:

[0185] κ λ =κ p,λ

[0186] In the band containing the gas absorption peak, the monochromatic absorption coefficient of the flame is composed of the monochromatic absorption coefficients of the particles and the gas, that is:

[0187] κ λ =κ p,λ +κ g,λ

[0188] The visible light field camera 1 measures negligible gas absorption at wavelengths λ1 (450 nm) and λ2 (700 nm), while the infrared light field camera 2 measures gas absorption at wavelength λ3 (1870 nm). The equations for calculating the particle temperature, particle absorption coefficient, and gas absorption coefficient at different wavelengths are as follows:

[0189]

[0190] The three equations are combined into a matrix equation system and the known radiation source term H is used λ (n) and the absorption peak wavelength of the gas, the soot particle temperature T(n) and the soot particle absorption coefficient κ can be solved by numerical methods (such as least squares method, iteration method, etc.)p,λ and the absorption coefficient of the gas to be measured κ g,λ .

[0191] Step 6: Use Mie theory and soot particle absorption coefficient to invert and calculate the soot particle concentration.

[0192] The radiation characteristics of soot particles are calculated using Mie theory. The absorption coefficient of soot is calculated as follows:

[0193]

[0194] Where, κ p,λ is the absorption coefficient of soot, f v is the soot particle concentration, E(m) is a function of the soot complex refractive index that varies with wavelength, and λ is the wavelength in micrometers.

[0195] The calculation formula of the radiation source term at the wavelength without gas absorption is obtained:

[0196]

[0197] Arranged available,

[0198]

[0199] The temperature and particle concentration can be calculated using the linear fitting method.

[0200] Step 7: Use the statistical narrow-band method to invert the concentration of the gas to be measured based on the gas absorption coefficient.

[0201] Similarly, the calculation formula for the radiation source term at a wavelength containing gas absorption is:

[0202]

[0203] After finishing, we can get:

[0204]

[0205] The gas concentration can be calculated using the statistical narrow-band method.

[0206] The specific calculation formula of the statistical narrow-band method is as follows:

[0207]

[0208] Among them, let the line strength be an inverse exponential distribution,

[0209]

[0210] Where, Y is the length of the path traveled by the light, f gis the concentration of the radiative gas, P represents the total gas pressure, represents the ratio of the average line width to the spacing, is the average line width, and is the average spacing between spectral lines, is the average absorption coefficient.

[0211] Step 8: Output the measurement results such as the temperature of the combustion flame, the concentration of gas components, the volume fraction of soot particles, and the spectral radiation absorption coefficient to complete the measurement.

[0212] like Figure 3 As shown, the present invention also provides a multi-light field camera device for a combustion field three-dimensional temperature, concentration, and particle information inversion system based on visible light and infrared light field cameras 2. The device comprises: a visible light field camera 1, an infrared light field camera 2, a synchronization controller 3; a data processing system 4; and a sensor bracket. The synchronization controller 3 controls the synchronous acquisition of all cameras; the visible light field camera 1 and the infrared light field camera 2 can move to cover the entire combustion flame through the sensor bracket 5, and transmit their spontaneous radiation information to the data processing system 4 through the output end; the data processing system 4 can process the obtained visible light and infrared light field radiation signals to reconstruct the combustion flame's temperature, gas component concentration, soot particle concentration, and spectral radiation characteristic field distribution with high spatial resolution and high precision.

[0213] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the invention. It should be understood that many modifications may be made to the illustrative embodiments, and that other arrangements may be devised, without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in ways other than those described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in conjunction with other described embodiments.

Claims

1. A method for inverting three-dimensional temperature, concentration, and particle information of a combustion field based on visible light and infrared light field cameras, characterized in that: include: Step 1: Use visible light field camera and infrared light field camera to collect the radiation light field image signal of the flame to obtain the visible light field measurement signal I K and infrared light field measurement signal I H ; Step 2: Using the blackbody radiation law, measure the visible light field signal I K and infrared light field measurement signal I H The flame blackbody radiation intensity is obtained by calibrating the blackbody furnace and measuring the signal I from the visible light field. K and infrared light field measurement signal I H , extract the gray value of the flame field image, calibrate the flame blackbody radiation intensity with the gray value of the flame field image, and obtain the flame radiation intensity distribution diagram I λ ; Step 3: Use the flame radiation intensity distribution diagram I λ , establish the radiation transfer equation, obtain the three-dimensional space of the combustion field, discretize the three-dimensional space of the combustion field into N cubic elements, construct the radiation energy equation group, and combine the Tikhonov regularization algorithm to obtain the radiation source term H at each wavelength λ ; Step 4: Use the radiation source term H λ and the absorption peak wavelength of the gas to be measured, and solve to obtain the black particle temperature, absorption coefficient and absorption coefficient of the gas to be measured; and use the soot particle temperature to obtain the three-dimensional temperature field of the flame; Step 5: Use Mie theory and soot particle absorption coefficient to invert and calculate the soot particle concentration; Step 6: Use the statistical narrow-band method to invert the concentration of the gas to be measured based on the gas absorption coefficient.

2. The method for inverting three-dimensional temperature, concentration and particle information of a combustion field based on visible light and infrared light field cameras according to claim 1 is characterized in that: In step 2, the radiation intensity distribution diagram of the flame I λ The method is: Using the blackbody radiation law, the flame monochromatic radiation intensity is obtained: h is Planck's constant, c is the speed of light, λ is the wavelength, k is the Boltzmann constant, T is the absolute temperature of the blackbody furnace, I b,λ is the blackbody radiation intensity, extract the visible light field measurement signal I K and infrared light field measurement signal I H According to the one-to-one correspondence between the blackbody radiation intensity and the grayscale value of the flame image, the grayscale value and the blackbody radiation intensity are marked to obtain the flame radiation intensity distribution diagram I λ .

3. The method for inverting three-dimensional temperature, concentration and particle information of a combustion field based on visible light and infrared light field cameras according to claim 2 is characterized in that: In step 3, the radiation transfer equation is: Where dω is the incident solid angle, k ext,λ is the attenuation coefficient of the medium in the microelement at wavelength λ, k abs,λ is the absorption coefficient of the medium in the microelement at wavelength λ, I b,λ (T) is the blackbody radiation intensity at wavelength λ, k sca,λ is the scattering coefficient of the medium in the microelement at wavelength λ, is the intensity of monochromatic radiation from the outside into the microelement in the direction of S' when the wavelength is λ, yes The flame radiates light from the direction of the incident Scattering phase function for directional scattering.

4. The method for inverting three-dimensional temperature, concentration and particle information of a combustion field based on visible light and infrared light field cameras according to claim 3 is characterized in that: In step 3, the three-dimensional space of the combustion field is discretized into N cubic elements using the following method: According to the properties of the combustion field, the radiation transfer equation is simplified to obtain the three-dimensional space of the combustion field, and then the three-dimensional space of the combustion field is discretized into N cubic elements: Where, I λ (x) is the monochromatic radiation intensity of ray x reaching the light field camera, κ λ (s) is the local absorption coefficient, I b,λ (s) is the local monochromatic blackbody radiation intensity, H λ (s) is the local radiation source term, κ λ (n) is the absorption coefficient of volume element n, H λ (s) is the radiation source term of volume element n, lx(n) is the ray length of ray x in volume element n, where H λ (n) = κ λ (n)I b,λ (n) Formula 4 I b,λ (s) is the monochromatic blackbody radiation intensity of volume element n, which is calculated according to Wien's law: T n is the temperature of element n, c1 is the first radiation constant, and c2 is the second radiation constant.

5. The method for inverting three-dimensional temperature, concentration and particle information of a combustion field based on visible light and infrared light field cameras according to claim 4 is characterized in that: In step 3, the radiation energy equations are: Where X is the total number of discrete directions in three-dimensional space, X is the total number of discrete directions in three-dimensional space, and x = 1, 2, ..., X.

6. The method for inverting three-dimensional temperature, concentration and particle information of a combustion field based on visible light and infrared light field cameras according to claim 5 is characterized in that: In step 3, obtain the radiation source term H at each wavelength λ The method is: Convert the radiation energy equations into matrix equation form: I λ = [I λ (1)……I λ (x)……I λ (X)] Formula Seven Convert to a matrix equation: I λ =A·H λ Formula 8 Where A is the ray length matrix of X-rays in each voxel; I λ is the monochromatic radiation intensity matrix of the X-rays reaching the light field camera; The matrix equation is solved using the Tikhonov regularization algorithm to obtain the radiation source term H at each wavelength. λ ; H λ =(A T A+αL T L) -1 A T I λ Formula 9 Where α is the regularization parameter, L is the regularization function, and the monochromatic radiation intensity matrix I λ Obtained through regularization solution.

7. The method for inverting three-dimensional temperature, concentration, and particle information of a combustion field based on a visible light and infrared light field camera according to claim 6 is characterized in that, in step 4, the radiation source term H is obtained by λ The matrix equation of the gas absorption peak wavelength is used to solve the soot particle temperature, soot particle absorption coefficient and the absorption coefficient of the gas to be measured as follows: In the band without gas absorption peak, let the monochromatic absorption coefficient of the flame be equal to the absorption coefficient of the soot particles: κ λ =κ p,λ Formula 10 κ p,λ The calculation equations for the soot absorption coefficient, particle temperature, and absorption coefficient are: In the wavelength band containing the absorption peak of the gas to be measured, the monochromatic absorption coefficient of the flame is composed of the absorption coefficients of the soot particles and the gas to be measured: κ λ =κ p,λ +κ g,λ Formula 12 The calculation equation using the soot particle temperature, absorption coefficient and absorption coefficient of the gas to be measured is: The soot particle temperature, soot particle absorption coefficient and the absorption coefficient of the gas to be measured are obtained by numerically solving equations at multiple wavelengths.

8. The method for inverting three-dimensional temperature, concentration and particle information of a combustion field based on visible light and infrared light field cameras according to claim 7 is characterized in that: In step 5, the method for inverting the soot particle concentration using Mie theory and the soot particle absorption coefficient is: The soot absorption coefficient calculation formula is used to calculate the radiation source term at a wavelength without gas absorption, and then the soot particle temperature and particle concentration are calculated by solving the overdetermined equation: Among them, the calculation formula of the absorption coefficient of soot is: Where, κ p,λ is the absorption coefficient of soot particles, f v is the soot particle concentration, E(m) is the function of the complex refractive index of the soot particles that varies with wavelength, λ is the wavelength in micrometers, n is the refractive index, k is the absorption factor, and f v is the concentration of soot particles. The radiation source term at the wavelength without gas absorption is: Arranged: Where c1 is the first radiation constant, c2 is the second radiation constant; The temperature and concentration of soot particles are obtained by calculating Formula 16 using the method of solving overdetermined equations.

9. The method for inverting three-dimensional temperature, concentration and particle information of a combustion field based on visible light and infrared light field cameras according to claim 8 is characterized in that: In step 6, the method for inverting the concentration of the gas to be measured based on the gas absorption coefficient using the statistical narrow-band method is: The concentration of the gas to be measured is calculated using the radiation source term calculation formula at a wavelength containing the absorption effect of the gas to be measured combined with the statistical narrowband method; The calculation formula for the radiation source term at a wavelength that includes gas absorption is: Arranged: Specific calculation formula of statistical narrow-band method: κ g,λ =exp(-W) Formula 19 Where W is the optical thickness, and the spectral line intensity in the narrow band is set to an inverse exponential distribution, and the concentration of the gas to be measured is calculated as: Where, Y is the length of the path traveled by the light, f g is the concentration of the radiative gas, P represents the total gas pressure, represents the ratio of the average line width to the spacing, is the average line width, and is the average spacing between spectral lines, is the average absorption coefficient.

10. A combustion field three-dimensional temperature, concentration, and particle information inversion system based on visible light and infrared light field cameras, the system being implemented based on the method according to any one of claims 1 to 9, characterized in that: include: Visible light field camera (1), infrared light field camera (2), synchronization controller (3) and data processing system (4); The visible light field camera (1) and the infrared light field camera (2) are relatively arranged on both sides of the flame to be measured, and filters are added to the visible light field camera (1) and the infrared light field camera (2); The visible light field camera (1) and the infrared light field camera (2) are controlled by a synchronization controller (3) to simultaneously collect light field information; and the collected signals are respectively sent to a data processing system (4); The data processing system (4) utilizes the received light field information in combination with the radiation transmission equation and the absorption peak wavelength of the gas to be measured to solve the soot particle temperature, absorption coefficient and absorption coefficient of the gas to be measured and the three-dimensional temperature field of the flame; and combines Mie theory and statistical narrowband method to invert the soot particle concentration and the gas to be measured concentration.

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