CN115077714A - Flame multispectral imaging measurement device, system and method based on optical fiber image transmission bundle - Google Patents
Flame multispectral imaging measurement device, system and method based on optical fiber image transmission bundle Download PDFInfo
- Publication number
- CN115077714A CN115077714A CN202210584172.2A CN202210584172A CN115077714A CN 115077714 A CN115077714 A CN 115077714A CN 202210584172 A CN202210584172 A CN 202210584172A CN 115077714 A CN115077714 A CN 115077714A
- Authority
- CN
- China
- Prior art keywords
- optical fiber
- image transmission
- flame
- camera
- objective lenses
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000005540 biological transmission Effects 0.000 title claims abstract description 68
- 239000013307 optical fiber Substances 0.000 title claims abstract description 67
- 238000005259 measurement Methods 0.000 title claims abstract description 36
- 238000000034 method Methods 0.000 title claims abstract description 31
- 238000000701 chemical imaging Methods 0.000 title claims abstract description 18
- 230000005855 radiation Effects 0.000 claims abstract description 49
- 239000004071 soot Substances 0.000 claims abstract description 21
- 238000003384 imaging method Methods 0.000 claims abstract description 15
- 238000000691 measurement method Methods 0.000 claims abstract description 8
- 239000000779 smoke Substances 0.000 claims description 16
- 238000004364 calculation method Methods 0.000 claims description 15
- 239000011521 glass Substances 0.000 claims description 9
- 230000005457 Black-body radiation Effects 0.000 claims description 6
- 239000011159 matrix material Substances 0.000 claims description 6
- 239000002245 particle Substances 0.000 claims description 5
- 230000003287 optical effect Effects 0.000 claims description 4
- 239000000835 fiber Substances 0.000 claims description 3
- 238000010521 absorption reaction Methods 0.000 claims description 2
- 230000004075 alteration Effects 0.000 claims description 2
- 238000009499 grossing Methods 0.000 claims description 2
- 230000011218 segmentation Effects 0.000 claims description 2
- 238000013519 translation Methods 0.000 claims description 2
- 238000002485 combustion reaction Methods 0.000 description 9
- 238000005516 engineering process Methods 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000013461 design Methods 0.000 description 2
- 230000003595 spectral effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009529 body temperature measurement Methods 0.000 description 1
- 238000010205 computational analysis Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 239000003350 kerosene Substances 0.000 description 1
- 238000012821 model calculation Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000004611 spectroscopical analysis Methods 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
- G01J5/48—Thermography; Techniques using wholly visual means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
- G01J5/0014—Radiation pyrometry, e.g. infrared or optical thermometry for sensing the radiation from gases, flames
- G01J5/0018—Flames, plasma or welding
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/06—Investigating concentration of particle suspensions
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T1/00—General purpose image data processing
- G06T1/0007—Image acquisition
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T5/00—Image enhancement or restoration
- G06T5/20—Image enhancement or restoration using local operators
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
- G01J2005/0077—Imaging
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/06—Investigating concentration of particle suspensions
- G01N15/075—Investigating concentration of particle suspensions by optical means
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Theoretical Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Dispersion Chemistry (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Health & Medical Sciences (AREA)
- Analytical Chemistry (AREA)
- Plasma & Fusion (AREA)
- Life Sciences & Earth Sciences (AREA)
- Radiation Pyrometers (AREA)
Abstract
The invention discloses a flame multispectral imaging measurement device, a flame multispectral imaging measurement system and a flame multispectral imaging measurement method based on an optical fiber image transmission beam, which relate to the technical field of radiation imaging measurement and solve the technical problem that images with different wavelengths cannot be obtained at the same time; in addition, in order to solve the problem that the conventional multispectral measurement scheme cannot ensure that the acquired images have consistency in time, the optical fiber image bundle transmission system is used for acquiring the multispectral images simultaneously, the time resolution and the space resolution of measurement are increased, and the method has an important application value for measuring the temperature and the soot concentration of flames at the tail nozzle of an aerospace engine or other jet flows.
Description
Technical Field
The application relates to the technical field of radiation imaging measurement, in particular to a flame multispectral imaging measurement device, system and method based on optical fiber image transmission bundles.
Background
An aircraft engine is a complex and precise thermal machine whose combustion conditions directly affect the performance, reliability and economy of the aircraft. The combustion chamber is the essential important part of engine, and when designing the combustion chamber, need guarantee that combustion stability is good, combustion efficiency is high, emission pollution is few, in order to promote the rationality of combustion chamber design and the efficiency of engine, need measure the flame at the engine tail nozzle department of direct reaction combustion chamber condition. The temperature profile is the most direct parameter for the reaction flame conditions; the aviation kerosene used by the aviation engine can form soot particles due to incomplete combustion, so that the soot concentration can also be used as one of design bases. The measurement of the temperature of the flame and the concentration of soot is therefore of crucial importance for the combustion diagnosis of aircraft engines.
There are many methods available for temperature measurement and soot measurement, mainly classified into invasive and non-invasive methods. Methods that can measure temperature and soot concentration simultaneously are laser-based methods, thermocouple particle density methods, and radiation spectroscopy-based methods. The thermocouple particle density method is an invasive measurement technology, can greatly influence the flow field characteristics of a measurement area, and is not suitable for measurement of an aircraft engine due to low response speed and large error. All laser-based methods need to add a laser light source and an initial signal and arrange a corresponding receiver at the same time, so that the method has the defects of complex optical path arrangement and difficult optical path calibration in industrial measurement occasions. The radiation imaging technology is a non-invasive measurement technology based on flame image processing, has the advantages of large projection data acquisition amount, no need of an additional light source, good noise resistance and the like, and is a measurement technology relatively suitable for measuring the tail nozzle of the aircraft engine.
In order to measure the temperature and the soot concentration with higher accuracy, a plurality of spectral information needs to be collected for fitting, so as to avoid errors brought by model calculation. The traditional multispectral method is mostly carried out in steady flame, the multispectral acquisition method is obtained by replacing a filter, but in engine measurement, because the flame of a tail nozzle is jet flame, the method cannot ensure that the flame states of the acquired image reactions under different wavelengths are the same. Therefore, there is a need for a device and method for measuring flame multi-spectral imaging to obtain more accurate three-dimensional temperature and soot concentration distribution of the flame.
Disclosure of Invention
The application provides a flame multispectral imaging measurement device, a flame multispectral imaging measurement system and a flame multispectral imaging measurement method based on optical fiber image transmission beams, and the technical purpose is to obtain flame images with the same wavelength at different angles through an optical fiber image transmission beam system and increase the spatial resolution of flame; and images of different wavelengths at different angles are acquired simultaneously, so that the three-dimensional temperature of the reconstructed flame and the smoke density distribution are acquired more accurately.
The technical purpose of the application is realized by the following technical scheme:
a flame multispectral imaging measuring device based on optical fiber image transmission beams comprises an optical fiber image transmission beam which is divided into nine parts, wherein each optical fiber image transmission beam is provided with a corresponding objective lens, and a filter plate is arranged in front of each objective lens; the junction of all the optical fiber image transmission beams is provided with a sight glass which is connected with a camera; the camera is provided with a filter plate;
all the objective lenses are arranged in the same plane of 180 degrees in the region to be measured, the included angle between every two adjacent objective lenses is 20 degrees, and the center of an image captured by each objective lens is in the same position; the objective lenses are divided into three groups according to a clockwise or anticlockwise sequence, each group comprises three adjacent objective lenses, each group of objective lenses are numbered in the same sequence, and the wavelengths of the filter plates in front of the objective lenses with the same number are the same.
A flame multispectral imaging measurement system based on optical fiber image transmission beams comprises an optical fiber image transmission beam measurement system, wherein the optical fiber image transmission beam measurement system comprises one-to-nine optical fiber image transmission beams, each optical fiber image transmission beam is provided with a corresponding objective lens, and a filter plate is arranged in front of each objective lens; the junction of all the optical fiber image transmission beams is provided with a sight glass which is connected with a camera, and the camera is connected with a computing system; the camera is provided with a filter plate;
all the objective lenses are arranged in the same plane of 180 degrees in the region to be measured, the included angle between every two adjacent objective lenses is 20 degrees, and the center of an image captured by each objective lens is in the same position; the objective lenses are divided into three groups according to a clockwise or anticlockwise sequence, each group comprises three adjacent objective lenses, each group of objective lenses are numbered in the same sequence, and the wavelengths of the filter plates in front of the objective lenses with the same number are the same.
A flame multispectral imaging measurement method based on optical fiber image transmission bundles comprises the following steps:
s1: arranging an optical fiber image transmission beam measuring system on a horizontal frame, wherein the optical fiber image transmission beam measuring system comprises an optical fiber image transmission beam with nine-in-one, aligning the field of view of the objective lens corresponding to the optical fiber image transmission beam so that the center of the image captured by each objective lens is at the same position, and establishing the pixel coordinate (x) in the optical fiber image transmission beam p ,y p ) With real world physical coordinates (x) r ,y r ) The corresponding relationship of (a);
s2: dividing the objective lenses into three groups according to a clockwise or anticlockwise sequence, wherein each group comprises three adjacent objective lenses, each group of objective lenses is numbered in the same sequence, and then, a filter with the same wavelength is additionally arranged in front of the objective lenses with the same number;
s3: capturing images through a camera and dividing the images into image quantity matched with the quantity of the objective lenses to obtain nine different divided images in nine directions under three wavelengths;
s4: setting filters with different wavelengths in front of a camera, capturing target surfaces of the black body furnace at different temperatures through the camera with the filters, acquiring gray values and corresponding black body monochromatic radiation intensities at different wavelengths, and fitting the gray values and the black body monochromatic radiation intensities to obtain a fitting relation of the gray values and the black body monochromatic radiation intensities;
s5: analyzing the divided images, supposing symmetrical arrangement of the optical fiber image transmission beam measuring system according to the symmetrical flame, obtaining flame information with six different angles for each wavelength, and solving according to the image information of the flame to obtain the three-dimensional distribution of the flame temperature and the smoke density to be measured.
The beneficial effect of this application lies in: compared with the existing radiation imaging technology, the method and the device increase the information quantity acquired in the spectral dimension, thereby improving the reconstruction precision of the field to be measured; in addition, in order to solve the problem that the conventional multispectral measurement scheme cannot ensure that the acquired images have consistency in time, the optical fiber image bundle transmission system is used for acquiring the multispectral images simultaneously, the time resolution and the space resolution of measurement are increased, and the method has an important application value for measuring the temperature and the soot concentration of flames at the tail nozzle of an aerospace engine or other jet flows.
Drawings
FIG. 1 is a block diagram of a measurement system according to the present application;
FIG. 2 is a diagram of an image distribution of an optical fiber image bundle according to the present application;
FIG. 3 is a flow chart of a measurement method described herein;
FIG. 4 is a flow chart of camera calibration in the present application;
FIG. 5 is a flow chart of the radiation intensity calibration in the present application;
FIG. 6 is a graph showing the results of the reconstruction of flame temperature and soot concentration;
fig. 7 is a schematic diagram comparing the measurement error of the present application with the conventional method.
Detailed Description
The technical solution of the present application will be described in detail below with reference to the accompanying drawings.
As shown in fig. 1, the flame multispectral imaging measurement system based on the optical fiber image transmission bundle comprises an optical fiber image transmission bundle measurement system, the optical fiber image transmission bundle measurement system comprises a one-to-nine optical fiber image transmission bundle, each optical fiber image transmission bundle is provided with a corresponding objective lens, and a filter is arranged in front of each objective lens; the junction of all the optical fiber image transmission beams is provided with a sight glass which is connected with a camera, and the camera is connected with a computing system; the camera is provided with a filter.
All the objective lenses are arranged in the same plane of 180 degrees in the region to be measured, the included angle between every two adjacent objective lenses is 20 degrees, and the center of an image captured by each objective lens is in the same position; the objective lenses are divided into three groups according to a clockwise or anticlockwise sequence, each group comprises three adjacent objective lenses, each group of objective lenses are numbered in the same sequence, and the wavelengths of the filter plates in front of the objective lenses with the same number are the same.
When the measurement is carried out by the optical fiber image transmission bundle measurement system, the main steps comprise: (1) arranging a one-to-nine optical fiber image transmission beam on a certain plane of a region to be detected, wherein an objective lens of the image transmission beam is ensured to be on the same plane and is used for acquiring an image of the region to be detected; (2) numbering the objective ends of the image transmission beams according to a certain sequence, and arranging filter plates with the same wavelength in front of the objective with the same number; (3) the camera with the wave band meeting the requirement set behind the viewing mirror of the image transmission beam is used for capturing images; (4) the captured images are gathered and transmitted to a computing system for subsequent computational analysis.
The imaging distribution of the optical fiber image transmission bundle in the camera is shown in fig. 2, wherein the number 1, 4 and 7 imaging blocks correspond to the flame image with the imaging wavelength 1; 2. no. 5 and No. 8 imaging blocks correspond to the flame image with the imaging wavelength of 2; 3. imaging blocks No. 6 and 9 correspond to the flame image at imaging wavelength 3.
As shown in fig. 3, the flame multi-spectral imaging measurement method based on the optical fiber image transmission bundle includes:
s1: arranging an optical fiber image transmission bundle measuring system on a horizontal frame, wherein the optical fiber image transmission bundle measuring system comprises an optical fiber image transmission bundle of nine minutes, aligning the field of view of the objective lens corresponding to the optical fiber image transmission bundle so that the center of the image captured by each objective lens is at the same position, and establishing the pixel coordinate (x) in the optical fiber image transmission bundle p ,y p ) With real world physical coordinates (x) r ,y r ) The corresponding relationship of (a);
specifically, aligning the fields of view of the objective lenses corresponding to the optical fiber image transmission beams so that the centers of the images captured by each objective lens are at the same position comprises:
s111: suspending a vertical line of a weight in the center of the area to be measured, wherein the vertical line is provided with a mark;
s112: capturing marks on the vertical line by using nine objective lenses, observing images captured by a sight glass through a camera, and adjusting the objective lenses to ensure that the center of each image captured by the sight glass is superposed with the marks on the vertical line;
s113: and fixing the adjusted objective lens end on the horizontal frame.
The camera calibration process is shown in FIG. 4, i.e. establishing the pixel coordinates (x) in the fiber bundle p ,y p ) With real world physical coordinates (x) r ,y r ) The corresponding relationship of (1) includes:
s121: placing a checkerboard at the position, opposite to the central objective, of the center of the area to be measured, and focusing the camera to the position where the target surface patterns in the nine objectives can be clearly shot;
s122: the camera captures an image at the end of the lens and divides the image into nine images with the same number as that of the objective lens according to the optical fiber image transmission bundle imaging principle;
s123: taking any angular point in the checkerboard as a coordinate origin to obtain two-dimensional physical coordinates (x) of all angular points on the checkerboard plane r ,y r )；
S124: respectively acquiring pixel coordinates (x) of the checkerboard in nine images obtained by segmentation pi ,y pi ) 1, 2.., 9, pixel coordinates (x) pi ,y pi ) Respectively with physical coordinates (x) r ,y r ) Fitting to obtain pixel coordinate (x) pi ,y pi ) The linear parameter from the two-dimensional physical coordinate is expressed as:
wherein, (X, Y, Z) represents the physical coordinates of a corner point; (T) x ,T y ,T z ) Representing a translation vector, namely pixel coordinates of the origin of a physical coordinate system in the camera; (C) x ,C y ) The method comprises the steps of representing an image principal point (assuming that the center of an image is coincident with the center of flame, the image principal point is a corrected numerical value which is a point on an actual image which is coincident with the center of flame), namely the pixel coordinate of the intersection point of an optical axis and an imaging plane;
representing a rotation matrix, namely converting the physical coordinate into angles which rotate around three coordinate axes respectively when the posture of the physical coordinate is consistent with that of the pixel coordinate;
s125: will physical coordinate (x) r ,y r ) Substituting in formula (1) to obtain pixel coordinate (x) r1 ,y r1 )，Calculating (x) r1 ,y r1 ) And (x) r ,y r ) And solving the difference coefficient;
s126: correcting the aberration through the difference coefficient;
s127: repeating the steps S121 to S126 until the result is stable, and finally outputting the relation which is the pixel coordinate (x) pi ,y pi ) And physical coordinates (x) r ,y r ) The corresponding relationship of (1).
S2: dividing the objective lenses into three groups according to a clockwise or anticlockwise sequence, wherein each group comprises three adjacent objective lenses, each group of objective lenses is numbered in the same sequence, and then, a filter with the same wavelength is additionally arranged in front of the objective lenses with the same number;
s3: capturing images through a camera and dividing the images into image quantity matched with the quantity of the objective lenses to obtain nine different divided images in nine directions under three wavelengths;
s4: the method comprises the steps of respectively arranging filter plates with different wavelengths in front of a camera, capturing target surfaces of the black body furnace at different temperatures through the camera with the filter plates, obtaining gray values and corresponding black body monochromatic radiation intensities at different wavelengths, and fitting the gray values and the black body monochromatic radiation intensities to obtain a fitting relation between the gray values and the black body monochromatic radiation intensities.
The process of calibrating the radiation intensity is shown in fig. 5, and specifically includes:
s41: a filter with a certain selected wavelength is arranged in front of the camera;
s42: presetting the set temperature of the black body furnace, and then calculating the set temperature of the black body furnace and the monochromatic radiation intensity of the black body under the selected wavelength according to the Planck black body radiation law, wherein the calculation formula is as follows:
wherein, I b,λ Representing the intensity of monochromatic radiation of a black body in W/m 2 ；c 1 Representing a first radiation constant, taken as 3.742 × 10 8 W·μm 4 /m 2 ；c 2 Representing a second radiation constant, taken to be 1.439 x 10 4 μ m.K; λ represents the wavelength of the front camera filter; t is n Indicating the set temperature of the blackbody furnace;
s43: capturing the target surface of the black body furnace at the set temperature of the black body furnace through a camera with a filter plate to obtain a target surface image at the set temperature of the black body furnace;
s44: extracting gray values of the images of the black body furnace at the set temperature and the selected wavelength;
s45: replacing the filter plate in front of the camera, and repeating the steps S43 to S44;
s46: changing the set temperature of the black body furnace, and repeating the steps S42 to S44 until the upper limit of the gray value of the image captured by the camera is reached;
s47: fitting the obtained gray values under different wavelengths and the black body monochromatic radiation intensity to obtain a fitting relation of the gray values and the black body monochromatic radiation intensity.
S5: analyzing the divided images, supposing symmetrical arrangement of the optical fiber image transmission beam measuring system according to the symmetrical flame, obtaining flame information with six different angles for each wavelength, and solving according to the image information of the flame to obtain the three-dimensional distribution of the flame temperature and the smoke density to be measured.
Specifically, step S5 includes:
s51: extracting the gray value of each divided image, and grouping the divided images with the same wavelength into a group;
s52: selecting 4 pixels including the upper and lower 2 pixels of a reference line in each divided image, carrying out average calculation on the gray values of the 4 pixels to obtain an average gray value, and obtaining a monochromatic radiation intensity value according to the fitting relation;
s53: calculating radiation intensity values in the grid, including:
dispersing the region to be measured into grids, dispersing each objective lens field of the optical fiber image transmission beam according to the field angle, regarding each discrete sight as a ray, obtaining the length of each ray in each grid, and obtaining the total monochromatic radiation intensity I of each ray λ (m r )Is/are as followsThe calculation formula is expressed as:
wherein k is λ (n) represents a smoke absorption coefficient of the grid; i is b,λ (n) represents monochromatic blackbody radiation intensity; h λ (n) represents a radiation source term whose value is equal to the calculated radiation intensity value in the grid; i is λ (m r ) Represents a ray m r Total monochromatic radiation intensity at the camera target surface;
according to the 9 angles captured by the optical fiber image transmission beam, acquiring radiation discrete ray paths under the 9 angles, and expressing as:
and obtaining the magnitude of the radiation intensity value in each grid through an inverse problem solving method, wherein the calculation formula is as follows:
A·x＝b； (5)
wherein A represents a path matrix, a matrix formed by the length of rays passing through the network; b is the monochromatic radiation intensity value obtained in step S52; x is the quantity to be solved, i.e. the radiation intensity value in each grid;
s54: solving flame temperature and soot concentration through radiant intensity values in the grid, including:
I b,λ (n) is calculated from Planck's Black-body radiation Law, k λ (n) is calculated by Rayleigh hypothesis for small particle size in Mie scattering theory, and the calculation formula is as follows:
wherein e (m) ═ Im [ (m) 2 -1)/(m 2 +2)]M represents the complex refractive index of soot; f. of v Represents the soot concentration; substituting formula (2) and formula (5) into formula (4) to obtain:
formula (7) is a calculation formula of flame temperature and soot concentration at a certain wavelength, three equations as shown in formula (6) are obtained according to three wavelengths obtained by the optical fiber image transmission bundle, and then the slope k and intercept b of a straight line are obtained in a straight line fitting manner, so that the flame temperature and soot concentration distribution is solved, and the calculation formula is expressed as follows:
s55: correcting the flame temperature and the smoke density obtained by calculation by utilizing a regularization and smoothing mode to obtain two-dimensional distribution of the flame temperature and the smoke density;
s56: and (4) reselecting different reference rows, and repeating the operations of the steps S53 to S55, so that the two-dimensional distribution of the flame temperature and the smoke black concentration under different flame heights is obtained, and finally the three-dimensional distribution of the flame temperature and the smoke black concentration is obtained.
As shown in fig. 6, five layers are selected as reconstruction study objects, each layer is divided into 45 × 45 grids, 10125 grids are counted, the temperature and the smoke density value in each grid are respectively studied, and five-layer reconstruction results and third-layer reconstruction results of the non-axisymmetric transient flame are shown in fig. 6. In fig. 6, it is shown that the overall temperature distribution gradually increases from the middle to the lower sides of the flame from the lower part to the higher part, and the soot concentration distribution shows an opposite trend, i.e. the trend gradually increases from the middle to the lower sides of the flame to the distribution with the higher sides of the flame, and the distribution with the lower sides of the flame gradually increases from the middle to the lower sides of the flame, which is better matched with the actual situation.
As shown in fig. 7, five layers are selected as reconstruction study objects, each layer is divided into 45 × 45 grids, and 10125 grids are counted, and reconstruction errors in each grid are studied respectively. When the method used in the application is adopted, the average reconstruction errors of the flame temperature and the smoke black concentration are 0.0374 x 10% and 0.377%, while the average reconstruction errors of the traditional measurement method are respectively 0.257% and 3.12%, which are far higher than those of the method used in the invention, so that the measurement superiority of the method is seen.
The foregoing is an exemplary embodiment of the present application, and the scope of the present application is defined by the claims and their equivalents.
Claims (7)
1. A flame multispectral imaging measuring device based on optical fiber image transmission beams is characterized by comprising one-to-nine optical fiber image transmission beams, wherein each optical fiber image transmission beam is provided with a corresponding objective lens, and a filter is arranged in front of each objective lens; a sight glass is arranged at the junction of all the optical fiber image transmission beams and is connected with a camera; the camera is provided with a filter plate;
all the objective lenses are arranged in the same plane of 180 degrees in the region to be measured, the included angle between every two adjacent objective lenses is 20 degrees, and the center of an image captured by each objective lens is in the same position; the objective lenses are divided into three groups according to a clockwise or anticlockwise sequence, each group comprises three adjacent objective lenses, each group of objective lenses are numbered in the same sequence, and the wavelengths of the filter plates in front of the objective lenses with the same number are the same.
2. A flame multispectral imaging measurement system based on an optical fiber image transmission bundle is characterized by comprising an optical fiber image transmission bundle measurement system, wherein the optical fiber image transmission bundle measurement system comprises an optical fiber image transmission bundle divided into nine parts, each optical fiber image transmission bundle is provided with a corresponding objective lens, and a filter plate is arranged in front of each objective lens; the junction of all the optical fiber image transmission beams is provided with a sight glass which is connected with a camera, and the camera is connected with a computing system; the camera is provided with a filter plate;
all the objective lenses are arranged in the same plane of 180 degrees in the region to be measured, the included angle between every two adjacent objective lenses is 20 degrees, and the center of an image captured by each objective lens is in the same position; the objective lenses are divided into three groups according to a clockwise or anticlockwise sequence, each group comprises three adjacent objective lenses, each group of objective lenses are numbered in the same sequence, and the wavelengths of the filter plates in front of the objective lenses with the same number are the same.
3. A flame multispectral imaging measurement method based on optical fiber image transmission bundles is characterized by comprising the following steps:
s1: arranging optical fibre image-transmitting beam measuring on horizontal frameThe measuring system comprises a nine-in-one optical fiber image transmission bundle, the field of view of the objective lens corresponding to the optical fiber image transmission bundle is aligned so that the center of the image captured by each objective lens is at the same position, and the pixel coordinate (x) in the optical fiber image transmission bundle is established p ,y p ) With real world physical coordinates (x) r ,y r ) The corresponding relationship of (a);
s2: dividing the objective lenses into three groups according to a clockwise or anticlockwise sequence, wherein each group comprises three adjacent objective lenses, each group of objective lenses is numbered in the same sequence, and then, a filter with the same wavelength is additionally arranged in front of the objective lenses with the same number;
s3: capturing images through a camera and dividing the images into image quantity matched with the quantity of the objective lenses to obtain nine different divided images in nine directions under three wavelengths;
s4: setting filters with different wavelengths in front of a camera, capturing target surfaces of the black body furnace at different temperatures through the camera with the filters, acquiring gray values and corresponding black body monochromatic radiation intensities at different wavelengths, and fitting the gray values and the black body monochromatic radiation intensities to obtain a fitting relation of the gray values and the black body monochromatic radiation intensities;
s5: analyzing the divided images, supposing symmetrical arrangement of the optical fiber image transmission beam measuring system according to the symmetrical flame, obtaining flame information with six different angles for each wavelength, and solving according to the image information of the flame to obtain the three-dimensional distribution of the flame temperature and the smoke density to be measured.
4. The method of claim 3, wherein the step S1 of aligning the field of view of the objective lens corresponding to the fiber optic image bundle so that the center of the image captured by each objective lens is at the same position comprises:
s111: suspending a vertical line of a weight in the center of the area to be measured, wherein the vertical line is provided with a mark;
s112: capturing marks on the vertical line by using nine objective lenses, observing images captured by a sight glass through a camera, and adjusting the objective lenses to ensure that the center of each image captured by the sight glass is superposed with the marks on the vertical line;
s113: and fixing the adjusted objective lens end on the horizontal frame.
5. The measurement method according to claim 4, wherein in step S1, the pixel coordinates (x) in the fiber optic bundle are established p ,y p ) With real world physical coordinates (x) r ,y r ) The corresponding relationship of (1) includes:
s121: placing a checkerboard at the position, opposite to the central objective, of the center of the area to be measured, and focusing the camera to the position where the target surface patterns in the nine objectives can be clearly shot;
s122: the camera captures an image at the end of the lens and divides the image into nine images with the same number as that of the objective lens according to the optical fiber image transmission bundle imaging principle;
s123: taking any angular point in the checkerboard as a coordinate origin to obtain two-dimensional physical coordinates (x) of all angular points on the checkerboard plane r ，y r )；
S124: respectively acquiring pixel coordinates (x) of the checkerboard in nine images obtained by segmentation pi ，y pi ) 1, 2.., 9, pixel coordinates (x) pi ，y pi ) Respectively with physical coordinates (x) r ，y r ) Fitting to obtain pixel coordinate (x) pi ，y pi ) The linear parameter from the two-dimensional physical coordinate is expressed as:
wherein, (X, Y, Z) represents the physical coordinates of a corner point; (T) x ，T y ，T z ) Representing a translation vector, namely pixel coordinates of the origin of a physical coordinate system in the camera; (C) x ，C y ) Pixel coordinates representing the image principal point, i.e., the intersection point of the optical axis and the imaging plane;
representing a rotation matrix, namely converting the physical coordinate into angles which rotate around three coordinate axes respectively when the posture of the physical coordinate is consistent with that of the pixel coordinate;
s125: will physical coordinate (x) r ，y r ) Substituting in formula (1) to obtain pixel coordinate (x) r1 ，y r1 ) Calculating (x) r1 ，y r1 ) And (x) r ，y r ) And solving the difference coefficient;
s126: correcting the aberration through the difference coefficient;
s127: repeating the steps S121 to S126 until the result is stable, and finally outputting the relation which is the pixel coordinate (x) pi ，y pi ) And physical coordinates (x) r ，y r ) The corresponding relationship of (1).
6. The measuring method according to claim 5, wherein the step S4 includes:
s41: a filter with a certain selected wavelength is arranged in front of the camera;
s42: presetting the set temperature of the black body furnace, and then calculating the set temperature of the black body furnace and the monochromatic radiation intensity of the black body under the selected wavelength according to the Planck black body radiation law, wherein the calculation formula is as follows:
wherein, I b，λ Representing the intensity of monochromatic radiation of a black body in W/m 2 ；c 1 Representing a first radiation constant, taken as 3.742 × 10 8 W·μm 4 /m 2 ；c 2 Representing a second radiation constant, taken to be 1.439 x 10 4 μ m.K; λ represents the wavelength of the front camera filter; t is a unit of n Indicating the set temperature of the blackbody furnace;
s43: capturing the target surface of the black body furnace at the set temperature of the black body furnace through a camera with a filter plate to obtain a target surface image at the set temperature of the black body furnace;
s44: extracting gray values of the images of the black body furnace at the set temperature and the selected wavelength;
s45: replacing the filter plate in front of the camera, and repeating the steps S43 to S44;
s46: changing the set temperature of the black body furnace, and repeating the steps S42 to S44 until the upper limit of the gray value of the image captured by the camera is reached;
s47: fitting the obtained gray values under different wavelengths and the black body monochromatic radiation intensity to obtain a fitting relation of the gray values and the black body monochromatic radiation intensity.
7. The measuring method according to claim 6, wherein the step S5 includes:
s51: extracting the gray value of each divided image, and grouping the divided images with the same wavelength into a group;
s52: selecting 4 pixels including the upper and lower 2 pixels of a reference line in each divided image, carrying out average calculation on the gray values of the 4 pixels to obtain an average gray value, and obtaining a monochromatic radiation intensity value according to the fitting relation;
s53: calculating radiation intensity values in the grid, including:
dispersing the region to be measured into grids, dispersing each objective lens field of the optical fiber image transmission beam according to the field angle, regarding each discrete sight as a ray, and acquiring the length of each ray in each grid
The total monochromatic radiation intensity I of each ray λ (m r )Is/are as followsThe calculation formula is expressed as:
wherein k is λ (n) represents a smoke absorption coefficient of the grid; i is b，λ (n) represents monochromatic blackbody radiation intensity; h λ (n) represents a radiation source term whose value is equal to the calculated radiation intensity value in the grid; i is λ (m r ) Represents a ray m r The total monochromatic radiation intensity reaching the camera target surface;
according to the 9 angles captured by the optical fiber image transmission beam, acquiring a radiation discrete ray path under the 9 angles, and expressing as:
and obtaining the magnitude of the radiation intensity value in each grid through an inverse problem solving method, wherein the calculation formula is as follows:
A·x＝b； (5)
wherein A represents a path matrix, a matrix formed by the length of rays passing through the network; b is the monochromatic radiation intensity value obtained in step S52; x is the quantity to be solved, i.e. the radiation intensity value in each grid;
s54: solving the flame temperature and the soot concentration through the radiation intensity values in the grid, including:
I b，λ (n) is calculated from Planck's Black-body radiation Law, k λ (n) is calculated by Rayleigh hypothesis for small particle size in Mie scattering theory, and the calculation formula is as follows:
wherein e (m) ═ Im [ (m) 2 -1)/(m 2 +2)]M represents the complex refractive index of soot; f. of v Represents the soot concentration;
substituting formula (2) and formula (5) into formula (4) to obtain:
the formula (7) is a calculation formula of flame temperature and soot concentration under a certain wavelength, three equations shown in the formula (6) are obtained according to three wavelengths obtained by the optical fiber image transmission bundle, and then the slope k and the intercept b of a straight line are obtained in a straight line fitting manner, so that the flame temperature and soot concentration distribution is solved, and the distribution is expressed as follows:
s55: correcting the flame temperature and the smoke density obtained by calculation by utilizing a regularization and smoothing mode to obtain two-dimensional distribution of the flame temperature and the smoke density;
s56: and (4) reselecting different reference rows, and repeating the operations of the steps S53 to S55, so that the two-dimensional distribution of the flame temperature and the smoke black concentration under different flame heights is obtained, and finally the three-dimensional distribution of the flame temperature and the smoke black concentration is obtained.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210584172.2A CN115077714A (en) | 2022-05-26 | 2022-05-26 | Flame multispectral imaging measurement device, system and method based on optical fiber image transmission bundle |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210584172.2A CN115077714A (en) | 2022-05-26 | 2022-05-26 | Flame multispectral imaging measurement device, system and method based on optical fiber image transmission bundle |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115077714A true CN115077714A (en) | 2022-09-20 |
Family
ID=83249911
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210584172.2A Pending CN115077714A (en) | 2022-05-26 | 2022-05-26 | Flame multispectral imaging measurement device, system and method based on optical fiber image transmission bundle |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115077714A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116358882A (en) * | 2023-04-10 | 2023-06-30 | 中国科学院力学研究所 | Method and system for researching flame dynamics characteristics of solid-liquid rocket engine |
-
2022
- 2022-05-26 CN CN202210584172.2A patent/CN115077714A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116358882A (en) * | 2023-04-10 | 2023-06-30 | 中国科学院力学研究所 | Method and system for researching flame dynamics characteristics of solid-liquid rocket engine |
| CN116358882B (en) * | 2023-04-10 | 2024-03-22 | 中国科学院力学研究所 | Method and system for researching flame dynamics characteristics of solid-liquid rocket engine |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Hossain et al. | Optical fiber imaging based tomographic reconstruction of burner flames | |
| CN108171758B (en) | Multi-camera calibration method based on minimum optical path principle and transparent glass calibration plate | |
| CN107401977B (en) | The imaging compensating method of refraction deviation is considered in the measurement of high temperature binocular stereo vision | |
| Li et al. | Light plane calibration and accuracy analysis for multi-line structured light vision measurement system | |
| Hossain et al. | Three-dimensional reconstruction of combustion flames through optical fiber sensing and CCD imaging | |
| CN110188321A (en) | A kind of primary and secondary mirror calibration method based on neural network algorithm | |
| CN112434598A (en) | Non-contact body temperature measuring method and system | |
| CN113218418B (en) | System and method for determining thermo-optic coupling effect of space extremely-high-precision pointing measuring instrument | |
| CN115077714A (en) | Flame multispectral imaging measurement device, system and method based on optical fiber image transmission bundle | |
| CN111899344B (en) | Flame emission tomography reconstruction device and method based on camera array | |
| Li et al. | Simultaneous measurement of flame temperature and absorption coefficient through LMBC-NNLS and plenoptic imaging techniques | |
| CN104406770B (en) | The distortion measurement device and distortion correction method of wave aberration measurement module | |
| Klemkowsky et al. | A direct comparison between conventional and plenoptic background oriented schlieren imaging | |
| Yuan et al. | Influence analysis of radiative properties and flame temperature reconstruction based on optical tomography | |
| JP6508896B2 (en) | Method of acquiring light spot gravity center position in optical wavefront sensor, optical wavefront measurement method and program | |
| CN109974893B (en) | Gradient refractive index flame three-dimensional temperature field measuring method | |
| CN106405671B (en) | A kind of infrared fusion visual detection method | |
| Yuan et al. | Practical calibration method for aerial mapping camera based on multiple pinhole collimator | |
| Sun et al. | Geometric calibration of focused light field camera for 3-D flame temperature measurement | |
| CN106525244B (en) | A kind of infrared fusion visual detection system | |
| CN114119747B (en) | Three-dimensional flow field flow display method based on PMD wave front detection | |
| CN110646095B (en) | Light field camera radiation sampling detection light processing method | |
| CN105784121B (en) | The a wide range of two-dimension temperature field measurement device of nine channel adaptives and its measurement method | |
| Zhao et al. | High throughput system for plant height and hyperspectral measurement | |
| CN110967115B (en) | Three-dimensional temperature field single-camera measurement imaging system and method based on multispectral diagnosis |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |