Method and system for simultaneously measuring two-dimensional distribution of liquid concentration and liquid movement
阅读说明:本技术 一种同时测量液体浓度和液体运动二维分布的方法及系统 (Method and system for simultaneously measuring two-dimensional distribution of liquid concentration and liquid movement ) 是由 胡文成 张宝华 窦义涛 杨帅 杨桐 于 2019-10-11 设计创作,主要内容包括:本申请涉及一种同时测量液体浓度和液体运动二维分布的方法,所述方法包括:生成至少两个可以汇聚形成有效测量区域平行的平面光束,所述有效测量区域包括若干的子区域;分别获取光源发出且通过所述子区域的入射光强和出射光强,并根据所述入射光强和出射光强确定所述子区域内的液体表面积,将各个体素内的液体表面积浓度重构后形成第一液体表面浓度二维分布和第二液体表面浓度二维分布;互相关所述第一液体表面浓度二维分布和第二液体表面浓度二维分布形成液体运动二维分布。本申请能够实现喷雾下方某截面液相二维速度测量,且为真正的瞬态测量,还可可实时显示液体浓度变化趋势,拓展了流量测量功能,最终实现了液体的浓度和速度的同时测量。(The application relates to a method for simultaneously measuring two-dimensional distribution of liquid concentration and liquid movement, which comprises the following steps: generating at least two plane light beams which can be converged to form an effective measuring area parallel, wherein the effective measuring area comprises a plurality of sub-areas; respectively obtaining incident light intensity and emergent light intensity which are emitted by a light source and pass through the sub-regions, determining the liquid surface area in the sub-regions according to the incident light intensity and the emergent light intensity, and reconstructing the liquid surface area concentration in each voxel to form a first liquid surface concentration two-dimensional distribution and a second liquid surface concentration two-dimensional distribution; and mutually correlating the first liquid surface concentration two-dimensional distribution and the second liquid surface concentration two-dimensional distribution to form liquid motion two-dimensional distribution. The liquid-phase two-dimensional velocity measuring device can realize two-dimensional velocity measurement of a liquid phase on a certain section below the spray, is real transient measurement, can display the liquid concentration change trend in real time, expands the flow measurement function, and finally realizes simultaneous measurement of the concentration and the velocity of liquid.)
1. A method for simultaneously measuring two-dimensional distribution of liquid concentration and liquid motion, which is characterized by comprising
Generating at least two parallel plane light beams, and converging the plane light beams to form an effective measuring area, wherein the effective measuring area is vertical to the flow direction of liquid, the effective measuring area comprises a plurality of sub-areas, and each plane light beam at least comprises two light sources which are sent according to a preset time interval and are converged;
acquiring incident light intensity and emergent light intensity which are emitted by at least one light source and pass through the sub-region, determining the liquid surface area in the sub-region according to the incident light intensity and the emergent light intensity, and reconstructing the liquid surface area concentration in each voxel to form first liquid surface concentration two-dimensional distribution;
acquiring incident light intensity and emergent light intensity which are emitted by at least one other light source and pass through the sub-region, determining the liquid surface area in the sub-region according to the incident light intensity and the emergent light intensity, and reconstructing the liquid surface area concentration in each voxel to form second liquid surface concentration two-dimensional distribution;
and mutually correlating the first liquid surface concentration two-dimensional distribution and the second liquid surface concentration two-dimensional distribution to form liquid motion two-dimensional distribution.
2. The method of claim 1, wherein each planar beam comprises at least two light sources, at least one of which is refracted and converged with another light source before being scattered to form a planar beam.
3. The method of simultaneously measuring two-dimensional distributions of liquid concentration and liquid motion of claim 1, wherein said at least two light sources are emitted at predetermined time intervals by coordinated control.
4. A method for simultaneously measuring two-dimensional distributions of liquid concentration and liquid motion according to any one of claims 1 to 3, wherein said light source is a pulsed laser.
5. The method of claim 1, wherein the incident light intensity and the emergent light intensity determine the surface area of the liquid in the sub-region, and are determined by the following relationship:
Iλe=Iλ0exp(-βλΔ)
in the formula IλeTo output a set light intensity, Iλ0β for incident light intensityλTo the attenuation coefficient, and in relation to the surface area of the liquid, Δ is the path taken by the light.
6. A system for simultaneously measuring two-dimensional distributions of liquid concentration and liquid motion, the system comprising
The device comprises at least two plane light beam forming devices, a liquid level sensor and a control device, wherein the at least two plane light beam forming devices are used for generating at least two parallel plane light beams and converging the plane light beams to form an effective measuring area, the effective measuring area is vertical to the flow direction of liquid, the effective measuring area comprises a plurality of sub-areas, and each plane light beam at least comprises two light sources which are sent at preset time intervals and converged;
the first liquid concentration distribution generating device is used for acquiring incident light intensity and emergent light intensity which are emitted by at least one light source and pass through the sub-area, determining the liquid surface area in the sub-area according to the incident light intensity and the emergent light intensity, and reconstructing the liquid surface area concentration in each voxel to form first liquid surface concentration two-dimensional distribution;
the second liquid concentration distribution generating device is used for acquiring incident light intensity and emergent light intensity which are emitted by at least one other light source and pass through the sub-area, determining the liquid surface area in the sub-area according to the incident light intensity and the emergent light intensity, and reconstructing the liquid surface area concentration in each voxel to form second liquid surface concentration two-dimensional distribution;
and the liquid motion distribution generating device is used for mutually correlating the first liquid surface concentration two-dimensional distribution and the second liquid surface concentration two-dimensional distribution to form a liquid motion two-dimensional distribution.
7. The system for simultaneously measuring two-dimensional distributions of liquid concentration and liquid motion according to claim 6, wherein said planar beam forming means comprises
At least two light source emitting modules for generating and emitting light sources;
at least one light source refraction module for reflecting or refracting the at least one light source at a predetermined angle to converge the light sources emitted by the at least two light source emission modules; and
the sheet light adjusting module is used for scattering the converged light source to form a plane light beam.
8. The system for simultaneously measuring two-dimensional distributions of liquid concentration and liquid motion according to claim 6, wherein said planar beam forming means further comprises
And the control module is used for coordinating and controlling at least two light source emitting modules to emit light sources according to a preset time interval.
9. The system for simultaneously measuring the two-dimensional distribution of the concentration and the movement of the liquid as claimed in any one of claims 6 to 8, wherein the light source generated by the light source emitting module is a pulsed laser.
10. The system for simultaneously measuring two-dimensional distributions of liquid concentration and liquid motion according to claim 6, wherein said first liquid concentration generating means and/or said second liquid concentration generating means determines the liquid surface area in said sub-area based on said incident light intensity and said emergent light intensity by the following relationship:
Iλe=Iλ0exp(-βλΔ)
in the formula IλeTo output a set light intensity, Iλ0β for incident light intensityλTo the attenuation coefficient, and in relation to the surface area of the liquid, Δ is the path taken by the light.
Technical Field
The application belongs to the technical field of imaging, and particularly relates to a method and a system for simultaneously measuring liquid concentration and liquid motion two-dimensional distribution.
Background
In an aircraft engine, a plurality of nozzles are provided, and the distribution of the concentration and the movement of liquid (fuel) sprayed by the nozzles needs to be measured in the design and test stages. By adopting the traditional SetScan technology, the method can only simultaneously measure the two-dimensional distribution of the surface diameter (SMD) of the plane and the surface area concentration of the particle diameter, but cannot measure the two-dimensional movement velocity distribution vertical to the axial plane of the spray, and has low time resolution and no function of recording images across frames.
Disclosure of Invention
It is an object of the present application to provide a method and system for simultaneously measuring a two-dimensional distribution of liquid concentration and liquid motion to solve or mitigate at least one of the problems of the background art.
In one aspect, the technical solution provided by the present application is: a method of simultaneously measuring a two-dimensional distribution of liquid concentration and liquid movement, the method comprising:
generating at least two parallel plane light beams, and converging the plane light beams to form an effective measuring area, wherein the effective measuring area is vertical to the flow direction of liquid, the effective measuring area comprises a plurality of sub-areas, and each plane light beam at least comprises two light sources which are sent at preset time intervals and converged;
acquiring incident light intensity and emergent light intensity which are emitted by at least one light source and pass through the sub-region, determining the liquid surface area in the sub-region according to the incident light intensity and the emergent light intensity, and reconstructing the liquid surface area concentration in each voxel to form first liquid surface concentration two-dimensional distribution;
acquiring incident light intensity and emergent light intensity which are emitted by at least one other light source and pass through the sub-region, determining the liquid surface area in the sub-region according to the incident light intensity and the emergent light intensity, and reconstructing the liquid surface area concentration in each voxel to form second liquid surface concentration two-dimensional distribution;
and mutually correlating the first liquid surface concentration two-dimensional distribution and the second liquid surface concentration two-dimensional distribution to form liquid motion two-dimensional distribution.
In an embodiment of the method of the present application, each planar light beam includes at least two light sources, and at least one light source is converged with another light source by refraction and then scattered to form a planar light beam.
In an embodiment of the method of the present application, the at least two light sources are emitted at predetermined time intervals by coordinated control.
In one embodiment of the method of the present application, the light source is a pulsed laser.
In an embodiment of the method of the present application, the incident light intensity and the emergent light intensity determine a liquid surface area in the sub-region, and are determined by the following relationship:
Iλe=Iλ0exp(-βλΔ)
in the formula IλeTo output a set light intensity, Iλ0β for incident light intensityλTo the attenuation coefficient, and in relation to the surface area of the liquid, Δ is the path taken by the light.
On the other hand, the technical scheme provided by the application is as follows: a system for simultaneously measuring a two-dimensional distribution of liquid concentration and liquid motion, the system comprising:
the device comprises at least two plane light beam forming devices, a light source, a liquid level sensor and a control device, wherein the at least two plane light beam forming devices are used for generating at least two parallel plane light beams and converging the plane light beams to form an effective measuring area, the effective measuring area is vertical to the flow direction of liquid, the effective measuring area comprises a plurality of sub-areas, and each plane light beam at least comprises two light sources which are sent according to a preset time interval and are converged;
the first liquid concentration distribution generating device is used for acquiring incident light intensity and emergent light intensity which are emitted by at least one light source and pass through the sub-area, determining the liquid surface area in the sub-area according to the incident light intensity and the emergent light intensity, and reconstructing the liquid surface area concentration in each voxel to form first liquid surface concentration two-dimensional distribution;
the second liquid concentration distribution generating device is used for acquiring incident light intensity and emergent light intensity which are emitted by at least one other light source and pass through the sub-area, determining the liquid surface area in the sub-area according to the incident light intensity and the emergent light intensity, and reconstructing the liquid surface area concentration in each voxel to form second liquid surface concentration two-dimensional distribution;
and the liquid motion distribution generating device is used for mutually correlating the first liquid surface concentration two-dimensional distribution and the second liquid surface concentration two-dimensional distribution to form liquid motion two-dimensional distribution.
In an embodiment of the system of the present application, the planar beam forming device includes:
at least two light source emitting modules for generating and emitting light sources;
at least one light source refraction module for reflecting or refracting the at least one light source at a predetermined angle to converge the light sources emitted by the at least two light source emission modules; and
the sheet light adjusting module is used for scattering the converged light source to form a plane light beam.
In an embodiment of the system of the present application, the planar beam forming apparatus further includes
And the control module is used for coordinating and controlling at least two light source emitting modules to emit light sources according to a preset time interval.
In an embodiment of the system of the present application, the light source generated by the light source emitting module is a pulsed laser.
In an embodiment of the system of the present application, the first liquid concentration generating device and/or the second liquid concentration generating device determines the liquid surface area in the sub-area according to the incident light intensity and the emergent light intensity by using the following relationship:
Iλe=Iλ0exp(-βλΔ)
in the formula IλeTo output a set light intensity, Iλ0β for incident light intensityλTo the attenuation coefficient, and in relation to the surface area of the liquid, Δ is the path taken by the light.
The method and the system for simultaneously measuring the liquid concentration and the liquid motion two-dimensional distribution can realize the two-dimensional speed measurement of the liquid phase of a certain section below the spray, can also display the liquid concentration change trend in real time for real transient measurement, expand the flow measurement function, and finally realize the simultaneous measurement of the concentration and the speed of the liquid.
Drawings
In order to more clearly illustrate the technical solutions provided by the present application, the following briefly introduces the accompanying drawings. It is to be expressly understood that the drawings described below are only illustrative of some embodiments of the invention.
FIG. 1 is a flow chart of a method for simultaneously measuring two-dimensional distributions of liquid concentration and liquid motion according to the present application.
FIG. 2 is a diagram of the system components for simultaneous measurement of two-dimensional distributions of liquid concentration and liquid motion according to the present application.
Fig. 3 is a schematic view of a scenario in which the present application is applied.
Fig. 4 is a sub-region diagram of an effective measurement region partition according to the present application.
Fig. 5 is a schematic diagram of effective measurement area division and imaging effect according to an embodiment of the present application.
Fig. 6 is a schematic diagram of an exposure timing sequence of a laser emitting and imaging device according to an embodiment of the present application.
FIG. 7 is a graph of two-plane liquid surface concentration distribution in an embodiment of the present application.
Fig. 8 is a vector diagram associated with the bipartite graph of fig. 7.
Detailed Description
In order to make the implementation objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the drawings in the embodiments of the present application.
In order to make the technical solution of the present application easier to understand, the following description will be made in conjunction with the method provided by the present application and the system provided by the present application.
As shown in fig. 1, the
step 110: generating at least two parallel plane light beams, converging the plane light beams to form an effective measuring area, wherein the effective measuring area is perpendicular to the flow direction of the liquid, the effective measuring area is divided into a plurality of sub-areas, and each plane light beam at least comprises two light sources which are sent at a preset time interval and are converged.
In order to generate at least two planar light beams according to the above method, at least two planar light
In the embodiment shown in fig. 2, three sets of planar light
In the system of the present application, the planar light beam forming means 210 includes at least two light
In the embodiment shown in fig. 2, two light
In addition, since the light sources emitted by the light
Further, the sheet
In some embodiments, the light
In order to make the light source easy to control and have better imaging effect, the light source in this application adopts a laser (pulse) light source, i.e. the light
In this application, the effective measurement area is substantially perpendicular to the flow direction of the liquid to be measured.
As shown in fig. 3, which is a scenario applicable to the present application, after the liquid to be measured is ejected from the nozzle, an umbrella-shaped fog region is formed in a circumferential direction, which gradually spreads, and in the present application, the effective measurement area (the speed measurement section in the figure) is located below the nozzle and is perpendicular to the spraying direction.
When the planar light beams generated by the plurality of planar light
As shown in fig. 4, the
Step 120: and acquiring incident light intensity and emergent light intensity which are emitted by at least one light source and pass through the sub-region, determining the surface area of the liquid in the sub-region according to the incident light intensity and the emergent light intensity, and reconstructing the surface area concentration of the liquid in each voxel to form a first two-dimensional liquid surface concentration distribution.
Step 130: and acquiring incident light intensity and emergent light intensity which are emitted by at least one other light source and pass through the sub-region, determining the surface area of the liquid in the sub-region according to the incident light intensity and the emergent light intensity, and reconstructing the surface area concentration of the liquid in each voxel to form two-dimensional distribution of the surface concentration of the second liquid.
In order to realize the planar concentration distribution measurement of the liquid, the system of the present application is provided with a first liquid concentration distribution generating device and a second liquid concentration distribution generating device, wherein the first liquid concentration distribution generating device and the second liquid concentration distribution generating device are the same, and in actual use, the first liquid concentration distribution generating device and the second liquid concentration distribution generating device are all imaging devices 220 (such as a CCD camera, a COMS camera or an SCOMS camera, etc.), which generate the two-dimensional distribution of the liquid concentration by acquiring and recording the incident light intensity and the emergent light intensity of the planar light beam, and determining the attenuation coefficient according to the incident light intensity and the emergent light intensity.
During measurement, when the spray sprayed from the nozzle passes through an effective measurement area below the nozzle, the absorption of the light source in a voxel is completed to cause light intensity attenuation, and the light intensity attenuation meets the Beer's-Lambert law. I.e. the intensity of the light I emitted through the voxelλeAnd the incident light intensity Iλ0Satisfying an exponential decay. The attenuated laser light passes through the lens and is incident into the
Wherein the incident light intensity and the emergent light intensityAnd attenuation coefficient βλThe travel of the light in the voxel satisfies the following relation:
Iλe=Iλ0exp(-βλΔ) (1)
in the formula IλeTo output a set light intensity, Iλ0β for incident light intensityλΔ is the path taken by the light, which is the carbon dioxide absorption coefficient.
The calculation of the surface area concentration reconstruction is the same as the SetScan technology, and as in the left figure embodiment of FIG. 5, the region to be detected is divided into a plurality of voxels according to the number of pixels of the selected imaging device, and the parameters β in the voxelsλΔ is the unknown sought. According to the
An equation similar to that shown in equation 4 is satisfied for each image formed by the
ΔiRelated to the refractive or relative refractive indices of the liquid and the ambient gas/liquid and the path taken by the light (i.e. the size of the voxel). The path traveled by light can be considered to be the same as a voxel, and the relative refractive index can be looked up from the properties of the fluid, thus Δiβ can be obtained according to the known quantityλiβ, as shown in equation 5λiRelated to the surface area of the liquid. From this, the liquid surface area (SetScan) within the voxel can be deducedTechnique, as shown on the right of fig. 5). And reconstructing the liquid surface concentration in each voxel to form a plane liquid surface concentration distribution.
βλΔ∝C (5)
Fig. 5 shows an example of a numerical simulation calculation result obtained in the case of using the effective measurement region division of the left diagram in the right diagram.
Finally, in step S140, the two-dimensional distribution of the surface concentration of the first liquid and the two-dimensional distribution of the surface concentration of the second liquid are correlated to form a two-dimensional distribution of the motion of the liquid.
The working principle of the transient two-dimensional velocity distribution measurement of the liquid motion in the application is based on the planar liquid surface concentration distribution obtained by the process. As shown in fig. 6, the light
It should be noted that the exposure time of
The cross-correlation algorithm includes direct cross-correlation calculation and fourier transform. These two methods are now equivalent under less displacement conditions. The fourier Transform method generally uses a Fast Fourier Transform (FFT) method which is faster in computation speed.
The FFT method is briefly described as follows:
for image 1g1(x, y) and image 2g2(x, y) are respectively FFT transformed to obtain
In the formula
Andare respectively an image g1(x, y) and g2And (x, y) FFT transformation. x, y are image coordinates. And omega is a frequency-domain value corresponding to Fourier transform.By using the translation characteristic of Fourier transform, the method can obtain
Wherein Δ x and Δ y are particle displacements.
Function(s)
By inverse Fourier transform
Substituting equation 8 into equation 9 results in
G(x,y)=g(x+△x,y+△y) (10)
Wherein g (x + △ x, y + y) is
G (x, y) has a maximum gray peak at (x, △ x, y + y), which is composed of 3 components (formula 11) due to the existence of background noise and other related quantities, the position of the maximum gray value (coherence peak) contains displacement information, so that the image displacement can be obtained by extracting the displacement of the peak center.R(S)=RC(S)+RD(S)+RF(S) (11)
In the formula RDAnd (S) represents the maximum gray value and represents the displacement information. RC(S)+RFAnd (S) is random correlation and background noise correlation quantity.
By the above processing, the relative displacement of the density distributions of the
in the formula, Δ s is a displacement (vector) of the liquid, and Δ t is a time interval for recording images of "planar liquid surface concentration distribution" at different times. When delta t → 0, the instantaneous velocity vector v of the liquid is obtained.
As shown in fig. 8, the vector diagram obtained by the cross-correlation processing of the images of the "planar liquid surface concentration distribution" in fig. 7a and 7b is obtained, and Matlab is used as the processing software.
The method and the system for simultaneously measuring the liquid concentration and the liquid motion two-dimensional distribution can realize the two-dimensional speed measurement of the liquid phase of a certain section below the spray, can also display the liquid concentration change trend in real time for real transient measurement, expand the flow measurement function, and finally realize the simultaneous measurement of the concentration and the speed of the liquid.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
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