CN117433998A - Device and method for testing local equivalence ratio of flame - Google Patents
Device and method for testing local equivalence ratio of flame Download PDFInfo
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- CN117433998A CN117433998A CN202311377869.3A CN202311377869A CN117433998A CN 117433998 A CN117433998 A CN 117433998A CN 202311377869 A CN202311377869 A CN 202311377869A CN 117433998 A CN117433998 A CN 117433998A
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
- G01N2021/0181—Memory or computer-assisted visual determination
Abstract
The invention aims to provide a device and a method for testing local equivalent ratio of flame, wherein the device comprises a point light source acquisition assembly, a light filtering assembly, a photoelectric conversion assembly and a data processing unit, wherein a light source of a certain local point is focused into the light filtering assembly through the point light source acquisition assembly for filtering, and a voltage signal is obtained through photoelectric conversion, and the local equivalent ratio of flame is obtained through calculation. The device and the testing method only collect the light source of a certain local position point of the flame, but the light sources of other position points cannot enter, and the device and the testing method have the function of resisting input interference. Therefore, the device does not need to shield an external interference light source for testing, has wide application scene, and can ensure that phi corresponding to local position points is accurately measured.
Description
Technical Field
The invention relates to the technical field of measurement of combustion diagnosis, in particular to the technical field of measurement of local equivalence ratio of flame.
Background
The combustion process of a gas turbine is affected by a plurality of factors, such as flow characteristics, fuel ratio, combustion chamber geometry and the like, and the mutual coupling of the factors leads to the complicated and complicated mechanism of combustion thermoacoustic instability, so that the shown combustion characteristics are also greatly different. The combustion equivalence ratio is one of the parameters of combustion characteristics, and refers to the ratio between the amount of oxygen required in the flame combustion process and the amount of oxygen provided by the fuel. It is used to measure the theoretical mixing ratio of fuel to oxygen to determine the efficiency of the combustion process and the product formation. By detecting and judging the combustion equivalent ratio of the flame in the combustion furnace, the effective supply amount of fossil fuel and air can be controlled. Is one of the effective means for improving the production efficiency and saving the cost.
A method, system and apparatus for identifying combustion equivalence ratio based on flame color as in CN 110263796B. The method comprises the steps of collecting flame RGB original image through a digital camera, and calculating the RGB original image to obtain the B/G value of the RGB image. And (5) inputting the B/G value into a flame equivalence ratio judgment model, and calculating to obtain the flame equivalence ratio. According to the method, after the flame image color information is identified through an image processing technology, the mixing condition of fuel and air, namely the equivalence ratio, can be indirectly obtained by utilizing the relation between the color and the equivalence ratio, and then the combustion state is judged.
During actual combustion of the flame, there may be a difference in fuel and oxidant concentrations in the different regions, i.e., the equivalence ratio at each local point is not uniform. It is then necessary to detect the equivalence ratio of the individual local points of the flame, to analyze the inhomogeneities in the flame and to identify possible local combustion problems, such as fuel segregation or local severe oxidation. The equivalence ratio of the local points in the monitored flame is more important in the actual flame equivalence ratio monitoring process.
However, in the method in the patent, the flame burning image is acquired by a digital camera, and then the flame equivalence ratio is obtained by image processing. The resolution and image quality of the digital camera may have an influence on the equivalence ratio judgment result of the local point. For example, low resolution or image noise can cause difficulties in accurately capturing and analyzing local point information of the flame, thereby affecting the accuracy of the determination. Also, flame combustion is dynamic, requiring real-time monitoring of the local equivalence ratio. However, the method needs to use complex image processing and analysis methods, if real-time monitoring is needed, the complexity of data processing is doubled, and the requirement on hardware performance is higher.
Disclosure of Invention
The invention aims to provide a device and a method for testing the flame local equivalent ratio, which can realize accurate measurement of the flame local point equivalent ratio, and have simple algorithm and lower requirement on hardware performance.
The invention is realized by the following technical scheme:
the device for testing the flame local equivalence ratio is characterized by comprising a point light source acquisition assembly, a light filtering assembly, a photoelectric conversion assembly and a data processing unit, wherein the light filtering assembly comprises an OH-based optical filter and a CH-based optical filter;
the point light source acquisition assembly comprises an optical assembly and an optical fiber beam splitter connected with the optical assembly, the optical assembly is used for acquiring a light source of a flame local point, the light source is focused to a point and then is input into the optical fiber beam splitter, and the optical fiber beam splitter equally divides an optical path into two paths: transmitting a first light beam lambda 1 and a second light beam lambda 2 to the OH group filter and the CH group filter respectively;
the OH group filter and the CH group filter respectively filter the transmission light beam I lambda 1 and the transmission light beam II lambda 2, and respectively transmit OH group autofluorescence lambda 3 and CH group autofluorescence lambda 4;
the photoelectric conversion component receives the OH group autofluorescence lambda 3 and the CH group autofluorescence lambda 4 and converts the OH group autofluorescence lambda 3 and the CH group autofluorescence lambda 4 into a corresponding voltage signal U1 and a voltage signal U2 respectively;
the data processing unit receives the first voltage signal U1 and the second voltage signal U2, and calculates a local equivalence ratio phi of flame;
the calculation formula is as follows:
wherein the value range of A is any value between 6.90 and 6.92, the value range of B is any value between 18.10 and 18.30, and the value range of C is any value between 12.86 and 12.88.
The optical component can be selected from the well-known Cassegrain lens in the prior art. Cassegrain lens is an optical lens design consisting of two or more reflective surfaces, with the purpose of capturing the light source at a localized point of the flame, focusing the diverging beam onto a focal point. The focused light beam enters the optical fiber beam splitter and is divided into two paths of transmission light beams in average: the transmission beam one lambda 1 and the transmission beam two lambda 2. The transmission light beam I lambda 1 and the transmission light beam II lambda 2 respectively enter the OH group filter and the CH group filter in the filter component.
A filter is an optical component in the prior art, and is used to filter light as it passes through the filter, which transmits or reflects light of a specified wavelength. In this case, the OH-based filter and the CH-based filter will filter the transmission beam one λ1 and the transmission beam two λ2, respectively, and transmit the OH-based autofluorescence λ3 with a wavelength of 315nm and the CH-based autofluorescence λ4 with a wavelength of 427nm to the photoelectric conversion component, respectively.
The photoelectric conversion component can be a combination of a photomultiplier tube and a multichannel power amplifier which are mature in the prior art. And the photomultiplier converts the two paths of optical signals of the OH group autofluorescence lambda 3 and the CH group autofluorescence lambda 4 into corresponding current signals respectively through the photoelectron effect. The two current signals then enter the multi-channel power amplifier. The multichannel power amplifier is a mature component in the photoelectric field in the prior art and is used for amplifying weak current signals into voltage signals. Here, amplified into two voltage signals: and the voltage signal UI and the voltage signal U2 are output to the data processing unit. And calculating the local equivalence ratio phi of the flame through the relation between the UI, the U2 and the phi, and outputting the local equivalence ratio phi.
Mathematical relationship:
wherein the value range of A is any value between 6.90 and 6.92, the value range of B is any value between 18.10 and 18.30, and the value range of C is any value between 12.86 and 12.88.
The A, the B and the C are constant parameters in mathematical relation formulas among the UI, the U2 and the phi, the values of the parameters can be defined in the limiting range, and a user can customize according to actual conditions to select an optimal matching numerical value to substitute the formula.
The device for testing the flame local equivalence ratio can focus the light source of a certain local point into the optical fiber beam splitter through the optical component in the point light source acquisition component, so that the device only can acquire the light source of a certain local position point of the flame, and the light sources of other position points cannot be acquired and focused into the optical fiber beam splitter through the optical component, and the device has the input interference resistance function. Therefore, the device does not need to shield an external interference light source for testing, has wide application scene, and can ensure that the phi corresponding to the local position point is accurately measured.
And the data processing unit only obtains the local equivalent ratio phi of the flame through the relation between the U1, the U2 and the local equivalent ratio phi, and no other complex operation algorithm exists. When the testing device monitors the equivalent ratio of flame in real time, simple mathematical relation operation does not cause operation burden on the data processing unit, and has lower requirement on hardware performance.
As a novel preferred aspect of the present invention, the point light source collecting assembly further includes two collimating mirrors respectively connected to the OH-based filter and the CH-based filter, and the collimating mirrors are configured to convert the first transmission beam λ1 and the second transmission beam λ2 into a first parallel light λ11 and a second parallel light λ21, respectively.
The optical fiber beam splitter equally divides the optical fiber into two paths: the transmission light beam I lambda 1 and the transmission light beam II lambda 2 are transmitted to the filtering component. The transmission beam I lambda 1 and the transmission beam II lambda 2 are transmitted inside the optical fiber beam splitter, have a certain transmission angle, and are totally reflected against the inner diameter of the optical fiber, so that the transmission beam I lambda 1 and the transmission beam II lambda 2 are transmitted along the extending direction of the optical fiber, and are not a group of parallel rays. The collimating lens is a mature optical element in the prior art and is used for converting divergent light rays into parallel light rays. Two collimating mirrors are respectively connected to the tail ends of two branches in the optical fiber beam splitter, so that the transmission light beam I lambda 1 and the transmission light beam II lambda 2 can be converted into parallel light beam lambda 11 and parallel light beam II lambda 21, and the parallel light beam I lambda 11 and the parallel light beam II lambda 21 respectively enter the OH-based optical filter and the CH-based optical filter in the optical filter assembly.
The distance between the parallel light rays does not change along with the change of the propagation distance, so that the position of the light filtering component does not need to be specially adjusted, and the light rays of each path can enter the light filtering component and are received and filtered by the OH-based optical filter and the CH-based optical filter. Also, since the light rays in the parallel light beams all have the same direction, they always remain parallel regardless of the distance traveled by the light rays, so that there is no fear that part of the light in the parallel light- λ11 may erroneously travel to the CH-based filter, and the parallel light-biλ21 may be the same.
The device can ensure the accuracy of the acquired optical signals, thereby ensuring the accuracy of the calculated local equivalence ratio phi.
As a preferred aspect of the present invention, a black box is provided outside the photoelectric conversion element for preventing natural light from entering the photoelectric conversion element.
The photoelectric conversion component is used for converting the OH group autofluorescence lambda 3 and the CH group autofluorescence lambda 4 into the corresponding voltage signal one U1 and the voltage signal two U2 respectively. Natural light enters the photoelectric conversion assembly and affects the actual collection values of the first voltage signal U1 and the second voltage signal U2. The black box is arranged outside the photoelectric conversion assembly and used for preventing natural light from entering the photoelectric conversion assembly, and the accuracy of the output voltage signal U1 and the voltage signal U2 can be ensured, so that the accuracy of the local equivalence ratio phi calculated by the device is ensured.
Preferably, the point light source collecting unit further includes a three-dimensional displacement table located below the optical unit and used for adjusting the spatial position of the optical unit.
The optical assembly needs to adjust the spatial position of the relative flame with high precision, so that the acquisition and focusing of the local point light sources and the detection of phi corresponding to different local points can be realized. The three-dimensional displacement table can be a mature DANTEC three-dimensional displacement table in the prior art, can realize 0.01mm accurate control, and can ensure stable operation under the condition of carrying maximum 30KG measuring equipment. The device can realize precise displacement adjustment of the optical component in three directions of x, y and z axes.
The testing method of the testing device for the flame local equivalence ratio is characterized by comprising the following steps of:
STEP1, a point light source acquisition STEP,
in this step, the optical component is utilized to reflect and focus the flame local point light source into the optical fiber beam splitter for multiple times;
STEP2: a step of branching the optical fiber,
the optical fiber beam splitter equally divides the optical path into two paths: the transmission light beam I lambda 1 and the transmission light beam II lambda 2 are respectively given to the OH group filter and the CH group filter;
STEP3: a filtering step of the filter is carried out,
the OH group filter and the CH group filter respectively filter the transmission light beam I lambda 1 and the transmission light beam II lambda 2, and respectively transmit the OH group autofluorescence lambda 3 and the CH group autofluorescence lambda 4;
STEP4: a photoelectric conversion step of converting the light into electric power,
the OH group autofluorescence lambda 3 and the CH group autofluorescence lambda 4 are respectively converted into the corresponding voltage signal one U1 and the voltage signal two U2 through the photoelectron effect;
STEP5: a step of calculation, in which,
calculating the local equivalence ratio phi by using the formula:
wherein the value range of A is any value between 6.90 and 6.92, the value range of B is any value between 18.10 and 18.30, and the value range of C is any value between 12.86 and 12.88.
The optical assembly consists of two or more reflecting surfaces, the purpose of which is to collect the light source of the local point of the flame, focusing the divergent light beam on the focal point. The focused light beam enters the optical fiber beam splitter and is divided into two paths of transmission light beams in average: the transmission beam one lambda 1 and the transmission beam two lambda 2. The OH group filter and the CH group filter are used for filtering the transmission light beam I lambda 1 and the transmission light beam II lambda 2 respectively, absorbing light of other wave bands and transmitting out the OH group autofluorescence lambda 3 with the wavelength of 315nm and the CH group autofluorescence lambda 4 with the wavelength of 427nm respectively. The lambda 3 and the lambda 3 optical signals are respectively converted into current signals through the photoelectron effect, and weak current signals are respectively amplified into voltage signals: the voltage signal one UI and the voltage signal two U2. And then calculating the local equivalence ratio phi of the flame through a formula.
The formula is:
wherein the value range of A is any value between 6.90 and 6.92, the value range of B is any value between 18.10 and 18.30, and the value range of C is any value between 12.86 and 12.88.
The A, the B and the C are constant parameters in mathematical relation formulas among the UI, the U2 and the phi, the values of the parameters can be defined in the limiting range, and a user can customize according to actual conditions to select an optimal matching numerical value to substitute the formula.
The method for testing the flame local equivalence ratio can focus a light source at a certain local point into the optical fiber beam splitter through multiple reflections by the optical component. The method only collects the light source of a certain local position point of the flame, and the light sources of other position points cannot be collected and focused into the optical fiber beam splitter through the optical component, so that the method has the function of resisting input interference. Therefore, the test method does not need to shield an external interference light source, has wide application scene, and can ensure that the phi corresponding to the local position point is accurately measured.
The local equivalent ratio phi of the flame is obtained only by the relation between the U1, the U2 and the local equivalent ratio phi, and no other complex operation algorithm exists. When the equivalent ratio of flame is monitored in real time, simple mathematical relation operation does not cause operation burden on required hardware, and the requirement on hardware performance is low.
As a preferred aspect of the present invention, the point light source collecting STEP1 includes the STEPs of:
STEP11: a beam of reverse light path is driven into the outlet of the optical fiber beam splitter, is emitted from the inlet of the optical assembly after passing through the optical assembly, and then generates a reverse light spot at the flame position;
STEP12: the distance between the optical component and the flame is adjusted so that the area of the light spot located at the flame position is minimized, and the distance between the optical component and the flame at the moment is defined as a distance d1.
STEP13: and keeping the distance between the optical component and the flame as the distance d1 unchanged, withdrawing the reverse light path, and reflecting and focusing the flame local point light source into the optical fiber beam splitter for multiple times by the optical component.
And a reverse light path is driven into the outlet of the point light source acquisition assembly, reversely passes through the optical assembly, is emitted from the outlet of the point light source acquisition assembly, and is beaten in the flame position area to form the light spot. Because of the reversibility of the light path, the local point light source in the flame in the area where the light spot is located can also enter the point light source acquisition assembly along the reverse light path in the forward direction, and enter the optical fiber beam splitter after being focused by the optical assembly. The acquisition and focusing of the local point light sources can be realized without adjusting the positions of the reflecting surfaces in the optical assembly.
The manner of adjusting the position of each reflecting surface in the optical assembly is more complicated because there are multiple reflecting surfaces to adjust, and the adjustment direction is not fixed, which is time consuming. According to the adjusting method, the distance between the flame and the optical assembly is adjusted by driving the reverse light path, the adjusting direction is single, and the adjusting direction is unique, so that the adjusting method is simpler and faster.
Preferably, in the STEP12, a black background plate is used to replace the flame, and after the distance between the optical component and the black background plate is adjusted so that the spot area on the black background plate is minimized, the distance d1 is recorded, and the black background plate is replaced with the flame.
Since the flame itself is a light source, the light spot in the reverse direction impinges on the flame, which is not easily recognized by the naked eye. The black background plate is used for replacing flame, and the tempering flame is replaced after the black background plate is adjusted to the optimal distance, so that the area of the light spots can be more clearly identified, and the distance adjustment is more accurate. The minimum area of the light spot after adjustment is ensured, so that the phi on the local position point of the flame is accurately measured.
As a preferred aspect of the present invention, the point light source collecting STEP2 further includes a collimation STEP: the first transmission light beam lambda 1 and the second transmission light beam lambda 2 are respectively converted into the first parallel light beam lambda 11 and the second parallel light beam lambda 21 through the collimating lens, and then the first parallel light beam lambda 11 and the second parallel light beam lambda 21 are respectively transmitted to the OH-based optical filter and the CH-based optical filter.
The transmission beam I lambda 1 and the transmission beam II lambda 2 are transmitted inside the optical fiber beam splitter, have a certain transmission angle, and are totally reflected against the inner diameter of the optical fiber, so that the transmission beam I lambda 1 and the transmission beam II lambda 2 are transmitted along the extending direction of the optical fiber, and are not a group of parallel rays. Two collimating mirrors are respectively connected to the tail ends of two branches in the optical fiber beam splitter, so that the transmission light beam I lambda 1 and the transmission light beam II lambda 2 can be converted into parallel light lambda I11 and parallel light II lambda 21, and the parallel light lambda I11 and the parallel light II lambda 21 can be respectively transmitted to the OH group optical filter and the CH group optical filter.
The distance between the parallel light rays does not change along with the change of the propagation distance, so that the position of the optical filter does not need to be specially adjusted, and the light rays of each path can be received and filtered by the OH-based optical filter and the CH-based optical filter. Also, since the light rays in the parallel light beams all have the same direction, they always remain parallel regardless of the distance traveled by the light rays, so that there is no fear that part of the light in the parallel light- λ11 may erroneously travel to the CH-based filter, and the parallel light-biλ21 may be the same.
The method can ensure the accuracy of the acquired optical signals, thereby ensuring the accuracy of the calculated local equivalence ratio phi.
In summary, the invention has the following beneficial effects:
1. the optical component focuses the light source of a certain local point into the optical fiber beam splitter, so that the device has the function of resisting input interference, does not need to shield an external interference light source, is wide in application scene, and can ensure that the local equivalence ratio phi is accurately measured.
2. The local equivalence ratio phi can be calculated by a simple formula without other complex operation algorithms. When the equivalent ratio of flame is monitored in real time, the load on the operation of the required hardware is avoided, and the requirement on the hardware performance is low.
3. The method for determining the focal length by the reverse light path has the advantages of single adjustment direction and unique adjustment direction, and can focus the light path more simply and rapidly.
4. The black background plate is used for replacing flame to adjust the distance, so that the area of the light spots can be more clearly identified, and the distance adjustment is more accurate.
Drawings
Fig. 1: the working schematic diagram of the device
In the figure: 1. the device comprises a point light source acquisition assembly, 11, an optical assembly, 12, an optical fiber beam splitter, 13, a collimating lens, 14, a three-dimensional displacement table, 2, a light filtering assembly, 21, an OH group light filter, 22, a CH group light filter, 3, a photoelectric conversion assembly, 4, a data processing unit, 5 and a flame combustion system.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The present embodiment is only for explanation of the present invention and is not to be construed as limiting the present invention, and modifications to the present embodiment, which may not creatively contribute to the present invention as required by those skilled in the art after reading the present specification, are all protected by patent laws within the scope of claims of the present invention.
As shown in fig. 1, the optical assembly 11 focuses light emanating from a local point source of flame into the fiber optic beam splitter 12. The optical component 11 may be a known well-known Cassegrain lens. Cassegrain lens is an optical lens design consisting of two or more reflective surfaces that focus divergent light sources. In the embodiment, the used Cassegrain lenses are all reflectors, the processing and manufacturing of the lenses are all performed by adopting a mode of coating films outside glass, the main and secondary lens substrates are all made of common K9 glass, an ultraviolet reinforced aluminum film and a magnesium fluoride protective film are sequentially coated from inside to outside, the reflectivity is more than 85%, the actual diameters of the main and secondary lenses are 168mm and 52mm respectively, the curvature radiuses are 302.521mm and 175.924mm respectively, the center thicknesses are 20mm and 12mm respectively, the diameter of a hole in the center of the main lens is 40mm, the distance between the two lenses is 152mm, the object distance is 452mm, and the image distance is 525mm.
A three-dimensional displacement table 14 is arranged below the optical assembly 11 for adjusting the spatial position of the optical assembly 11. The optical assembly 11 requires a high precision adjustment of the spatial position relative to the flame, so that the acquisition and focusing of the local point light sources and the detection of Φ corresponding to different local points can be achieved. The three-dimensional displacement table 14 can be a mature DANTEC three-dimensional displacement table in the prior art, can realize 0.01mm accurate control, and can ensure stable operation under the condition of carrying maximum 30KG measuring equipment. The device can realize the precise displacement adjustment of the optical component 11 in three directions of x, y and z axes.
The method for determining the reasonable space position between the optical component and the flame comprises the following specific modes of collecting and focusing the flame local point light source:
a reverse light path is driven from the outlet of the point light source collecting assembly 1, reversely passes through the optical assembly 11, is emitted from the outlet of the point light source collecting assembly, and is beaten in a flame position area to form a light spot. The black background plate is used for replacing the flame, the distance between the optical component 11 and the black background plate is adjusted, so that the light spot area on the black background plate is minimized, and the distance d1 between the optical component 11 and the flame at the moment is recorded. The flame was replaced back to the black background plate. Keeping the distance between the optical assembly 11 and the flame constant at the distance d1, and evacuating the reverse light path.
Because of the reversibility of the light path, the local point light source in the flame in the area where the light spot is located can also enter the point light source acquisition assembly 1 along the reverse light path in the forward direction, and enter the optical fiber beam splitter 12 after being focused by the optical assembly 11. The acquisition and focusing of the local point light sources can be achieved without adjusting the position of each reflecting surface in the optical assembly 11.
The manner of adjusting the position of each reflecting surface in the optical assembly 11 is more complicated because there are multiple reflecting surfaces to adjust, and the adjustment direction is not fixed, which is time consuming. According to the adjusting method, the distance between the flame and the optical component 11 is adjusted by driving the reverse light path, the adjusting direction is single, and the adjusting direction is unique, so that the adjusting method is simpler and faster.
The focused beam enters the optical fiber beam splitter 12 and is divided into two transmission beams: transmission beam one λ1 and transmission beam two λ2. Two collimating lenses 13 are respectively connected to the tail ends of the two branches in the optical fiber beam splitter 12, and can convert the transmission light beam I lambda 1 and the transmission light beam II lambda 2 into parallel light beam lambda 11 and parallel light beam II lambda 21, and respectively enter an OH-based filter 21 and a CH-based filter 22 in the filter component 2.
Since the distance between the parallel light beams does not change along with the change of the propagation distance, the position of the filter assembly 2 does not need to be specially adjusted, and the light beams of each path can enter the filter assembly 2 and be received and filtered by the OH-based filter 21 and the CH-based filter 22. Since the light rays in the parallel light beams all have the same direction and remain parallel regardless of the distance traveled by the light rays, there is no fear that part of the light in the parallel light beam lambda 11 will erroneously travel to the CH-based filter 22, and the parallel light beam lambda 21 is the same.
The OH group filter 21 and the CH group filter 22 filter the parallel light I11 and the parallel light II 21, respectively, and transmit OH group autofluorescence lambda 3 with a wavelength of 315nm and CH group autofluorescence lambda 4 with a wavelength of 427nm to the photoelectric conversion element 3, respectively. In this embodiment, the OH-group filter 21 and the CH-group filter 22 are narrow-band filters of Semrock in the prior art, and the types are FF01-315/15-25 and FF01-427/10-25, respectively, wherein the former is used for measuring the OH-group luminescence band, and the latter is used for measuring the CH-group luminescence band.
The photoelectric conversion unit 3 may be a combination of photomultiplier and multichannel power amplifier, which are well known in the art. The photomultiplier converts the two paths of optical signals of lambda 3 and lambda 3 into corresponding current signals respectively through the photoelectron effect. The two current signals then enter the multi-channel power amplifier. Multichannel power amplifiers are well-established components in the photovoltaic field in the prior art for amplifying weak current signals into voltage signals. Here, amplified into two voltage signals: the voltage signal one UI and the voltage signal two U2 are output to the data processing unit 4.
The black box 31 is arranged outside the photoelectric conversion assembly 3 and is used for preventing natural light from entering the photoelectric conversion assembly 3, so that the accuracy of the output voltage signal U1 and the voltage signal U2 can be ensured, and the accuracy of the local equivalence ratio phi calculated by the device is ensured.
And calculating the flame local equivalence ratio phi through the relation between UI, U2 and phi, and outputting the flame local equivalence ratio phi.
The formula is:
wherein the value range of A is any one value between 6.90 and 6.92, the value range of B is any one value between 18.10 and 18.30, and the value range of C is any one value between 12.86 and 12.88.
The specific derivation process of the formula comprises the following steps:
STEP1 defines the overall equivalence ratio of the flame as Collecting a local light source point in standard flame, wherein the standard flame is->Is known. Different->Can be obtained by controlling the flow of air reacting with the fuel by means of a flow meter. The collected light beams of the local light source point are focused firstly and then are equally divided into two paths of transmission light beams: transmission beam one λ1 and transmission beam two λ2; the transmission beam I lambda 1 and the transmission beam II lambda 2 output OH group autofluorescence lambda 3 and CH group autofluorescence lambda 4 after wavelength absorption respectively; the OH group autofluorescence lambda 3 and the CH group autofluorescence lambda 4 are subjected to photoelectric conversion to respectively obtain a corresponding voltage signal UI and a voltage signal U2;
STEP2: repeatedly collecting voltage signal UI and voltage signal U2 corresponding to other local light source points of standard flame, repeatedly testing each local light source point on the same standard flame for 10 times, averaging the measured voltage signals UI to obtain average voltage signal IAveraging the multiple voltage signals two U2 to obtain an average voltage signal two +.>
Because the flame shows high symmetry characteristic in the radial direction, only the right half area in the radial direction of the flame is selected to be measured, the Y-axis direction measuring area is 0-6.5mm, the Z-axis direction measuring area is an area 1-8cm above the central line of the nozzle of the combustion nozzle, and fixed point data are acquired every 0.7 mm. In order to ensure the accuracy of mathematical relationship, the measurement points comprise the flame root, the flame top frontal surface and the average value of all spatial samples in the flame, and mathematical fitting is carried out to avoid the influence of too small change of the heat release rate of the flame root and too large change of the heat release rate at the flame frontal surface.
STEP3: STEP1 and STEP2 were repeated for a plurality of different speciesIs measured to obtain a plurality of groups of correspondingAnd->And performing relation fitting to obtain a mathematical relation formula 1:
based on mathematical relationship 1, mathematical relationship 2 between UI, U2 and Φ is derived:
table 1 below is a partial data table of one of the tests.
TABLE 1
Repeated tests are carried out on the same standard flame and the same local light source point for a plurality of times, so that the influence of the contingency of data at a certain moment on the test result can be avoided, the mathematical relation obtained by linear fitting is more real and accurate, and thus the accurate measurement of phi is realized.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (8)
1. The device for testing the flame local equivalence ratio is characterized by comprising a point light source acquisition assembly (1), a light filtering assembly (2), a photoelectric conversion assembly (3) and a data processing unit (4), wherein the light filtering assembly (2) comprises an OH group filter (21) and a CH group filter (22);
the point light source acquisition assembly (1) comprises an optical assembly (11) and an optical fiber beam splitter (12) connected with the optical assembly (11), the optical assembly (11) is used for acquiring a light source of a flame local point, the light source is focused to a point and then is input into the optical fiber beam splitter (12), and the optical path is equally divided into two paths by the optical fiber beam splitter (12): a transmission beam I lambda 1 and a transmission beam II lambda 2 respectively to the OH group filter (21) and the CH group filter (22);
the OH group filter (21) and the CH group filter (22) respectively filter the transmission light beam I lambda 1 and the transmission light beam II lambda 2 and respectively transmit OH group autofluorescence lambda 3 and CH group autofluorescence lambda 4;
the photoelectric conversion component (3) receives the OH group autofluorescence lambda 3 and the CH group autofluorescence lambda 4 and converts the OH group autofluorescence lambda 3 and the CH group autofluorescence lambda 4 into a corresponding voltage signal U1 and a voltage signal U2 respectively;
the data processing unit (4) receives the first voltage signal U1 and the second voltage signal U2, and calculates to obtain a local equivalence ratio phi of flame;
the calculation formula is as follows:
wherein the value range of A is any value between 6.90 and 6.92, the value range of B is any value between 18.10 and 18.30, and the value range of C is any value between 12.86 and 12.88.
2. The device for testing the local equivalence ratio of flames according to claim 1, wherein the point light source acquisition assembly (1) further comprises two collimating mirrors (13) respectively connected with the OH-based filter (21) and the CH-based filter (22), and the collimating mirrors (13) are used for converting the transmission light beam I lambda 1 and the transmission light beam II lambda 2 into parallel light beam I lambda 11 and parallel light beam II lambda 21 respectively.
3. The device for testing the local equivalence ratio of flames according to claim 1, wherein a black box is arranged outside the photoelectric conversion assembly (3) and is used for preventing natural light from entering the photoelectric conversion assembly (3).
4. A device for testing the local equivalence ratio of flames according to any of claims 1 to 3, characterized in that the point light source acquisition assembly (1) further comprises a three-dimensional displacement table (14) which is positioned below the optical assembly (11) and is used for adjusting the spatial position of the optical assembly (11).
5. The method for testing a flame local equivalence ratio testing device according to any one of claims 1-4, comprising the steps of:
STEP1, a point light source acquisition STEP,
in this step, a local point source of flame is reflected a plurality of times by means of the optical assembly (11) and focused into the optical fiber beam splitter (12);
STEP2: a step of branching the optical fiber,
the optical fiber beam splitter (12) equally divides the optical path into two paths: the transmission light beam I lambda 1 and the transmission light beam II lambda 2 are respectively given to the OH group filter (21) and the CH group filter (22);
STEP3: a filtering step of the filter is carried out,
the OH group filter (21) and the CH group filter (22) respectively filter the transmission light beam I lambda 1 and the transmission light beam II lambda 2, and respectively transmit the OH group autofluorescence lambda 3 and the CH group autofluorescence lambda 4;
STEP4: a photoelectric conversion step of converting the light into electric power,
the OH group autofluorescence lambda 3 and the CH group autofluorescence lambda 4 are respectively converted into the corresponding voltage signal one U1 and the voltage signal two U2 through the photoelectron effect;
STEP5: a step of calculation, in which,
calculating the local equivalence ratio phi by using the formula:
wherein the value range of A is any one value between 6.90 and 6.92, the value range of B is any one value between 18.10 and 18.30, and the value range of C is any one value between 12.86 and 12.88.
6. The method according to claim 5, wherein the STEP of collecting the point light source STEP1 comprises the STEPs of:
STEP11: a beam of reverse light path is driven into the outlet of the optical fiber beam splitter (12), is emitted from the inlet of the optical component (11) after passing through the optical component (11), and then generates a reverse light spot at the flame position;
STEP12: adjusting the distance between the optical component (11) and the flame so as to minimize the spot area at the flame position, and defining the distance between the optical component (11) and the flame at the moment as a distance d1;
STEP13: and keeping the distance between the optical component (11) and the flame unchanged at a distance d1, withdrawing the reverse light path, and reflecting and focusing the flame local point light source into the optical fiber beam splitter (12) for multiple times by the optical component (11).
7. The method according to claim 6, wherein in STEP12, a black background plate is used instead of the flame, and the distance between the optical element (11) and the black background plate is adjusted so that the distance d1 is recorded and the black background plate is replaced with the flame after the spot area on the black background plate is minimized.
8. The method of claim 5, wherein the STEP of collecting STEP2 of point light sources further comprises a STEP of collimation: the first transmission light beam lambda 1 and the second transmission light beam lambda 2 are respectively converted into the first parallel light beam lambda 11 and the second parallel light beam lambda 21 through the collimating lens (13), and then the first parallel light beam lambda 11 and the second parallel light beam lambda 21 are respectively transmitted to the OH-based optical filter (21) and the CH-based optical filter (22).
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