CN109030312B - Device and method for testing flow characteristics of pore liquid in porous medium - Google Patents
Device and method for testing flow characteristics of pore liquid in porous medium Download PDFInfo
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- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
- G01N15/082—Investigating permeability by forcing a fluid through a sample
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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Abstract
The invention discloses a device and a test method for researching the flow characteristics of pore liquid in a porous medium, namely a method and a device for measuring the flow characteristics of the liquid in the porous medium and the movement rule of fine particles by a non-invasive means. The method is characterized in that an indoor model test is used for carrying out a porous medium seepage test, and the relationship between the flow characteristic and fine particle migration rule of pore liquid and factors such as water head gradient, particle compactness, particle gradation and the like is measured.
Description
Technical Field
The invention relates to a test method and a test device for simulating the flow characteristics of pore liquid in a porous medium in civil engineering and hydraulic engineering, and belongs to the field of soil body infiltration damage rule test.
Background
Piping is the phenomenon that fine soil particles are carried out along pores formed by framework particles under the action of seepage, and is a main form of seepage damage. The natural soil body is a porous heterogeneous medium consisting of solid particles with different sizes, and when piping occurs, the solid particles in the soil body are changed from an original static state to a moving state under a certain hydraulic condition. Therefore, the piping is the process of phase change of partial soil. The pore channel in the natural soil body has changeable shape and high three-dimensional degree, the pore flow velocity is unevenly distributed in the seepage field, the movement of fine particles is caused by the dragging force of pore seepage, and the porous material has the characteristics of small starting range, high speed, complex migration path and more influence factors. Therefore, it is the key point to study the piping to study the flow characteristics of the pore liquid and the movement law of the fine particles in the internal pores.
In a traditional geotechnical test, a sensor is often embedded to measure the flow characteristics of liquid, the movement condition of particles and the like. The 'invasive' measuring method can destroy the original phase state of the soil body to different degrees, and the deviation of the measuring result is caused.
In the prior art, a series of researches are carried out on the relationship between the critical state, the phase change rate and the like of soil body phase change and the physical properties of a solid-liquid phase in the piping process, the relationship between the soil body phase change rule and the soil body characteristics such as particle grading, compactness, seepage velocity and the like is explored, but the research on the flow characteristic of pore liquid in a porous medium and the movement rule of fine particles under the seepage action need to be further researched through non-invasive measurement.
Disclosure of Invention
The invention provides a method and a device for measuring the liquid flow characteristics and fine particle movement rules in a porous medium by a non-invasive means. The method is characterized in that an indoor model test is used for carrying out a porous medium seepage test, and the relationship between the flow characteristic and fine particle migration rule of pore liquid and factors such as water head gradient, particle compactness, particle gradation and the like is measured.
The technical scheme adopted for achieving the purpose of the invention is that the device for testing the flow characteristic of the pore liquid in the porous medium is characterized by mainly comprising a sample box, an upstream water head applying device, a downstream water head applying device, a water barrel, a water pump, a digital single lens reflex, a laser lamp holder and a plurality of silica gel hoses.
The side wall of the sample box is made of ultra-white glass, the lower bottom of the sample box is sealed and placed on the experiment platform, and the upper end of the sample box is open. The upper end opening of the sample box can be blocked by a sealing plate.
The upstream water head applying device comprises a sliding rod I, organic glass drums I-I and organic glass drums I-II. The lower end of the slide bar I is fixed on the experiment platform. The organic glass barrel I-I is hung on the sliding rod I through a sliding block. The organic glass barrel I-II is positioned in the organic glass barrel I-I.
After the water pump pumps the liquid in the bucket through the silica gel hose I, the liquid is conveyed into the organic glass drum I-II through the silica gel hose II. After the organic glass drum I-II is filled with the liquid, the liquid overflows into the organic glass drum I-I. A water outlet at the lower end of the organic glass barrel I-I is connected into the water barrel through a silica gel hose III, so that the liquid in the organic glass barrel I-I flows back to the water barrel.
And a water outlet at the lower end of the organic glass drum I-II is connected to a water inlet at the bottom of the sample box through a silica gel hose IV. The silica gel hose IV penetrates through the bottom of the organic glass drum I-I. And a valve I is arranged on the silica gel hose IV.
The downstream water head applying device comprises a sliding rod II, an organic glass cylinder II-I and an organic glass cylinder II-II.
And the lower end of the sliding rod II is fixed on the experiment platform. The organic glass barrel II-I is hung on the sliding rod II through the sliding block. The organic glass barrel II-II is positioned in the organic glass barrel II-I. The sealing plate configured on the sample box is provided with a water outlet, and the water outlet is connected into an organic glass drum II-II through a silica gel hose VI. Silica gel hose VI has valve II. After the liquid in the organic glass drum II-II is filled, the liquid overflows into the organic glass drum II-I. The water outlet at the lower end of the organic glass drum II-I is connected into the water barrel through a silica gel hose V.
The height of the organic glass drum I-I is adjusted through the sliding block on the sliding rod I. The height of the organic glass drum II-I is adjusted through the sliding block on the sliding rod II. The bottom of the organic glass barrel I-II is always higher than that of the organic glass barrel II-II.
The laser lamp head is positioned on one side of the sample box and emits a laser surface to the sample box. The digital single lens reflex camera is aligned with the sample box for shooting, and the axis of the lens is vertical to the laser surface.
The invention also discloses a test method based on the device for testing the flow characteristics of the pore liquid in the porous medium, which is characterized by comprising the following steps of:
preparing colorless transparent solid particles and transparent solution, wherein the refractive indexes of the colorless transparent solid particles and the transparent solution are the same. And preparing the tracer particles.
According to the set grading and compactness, a plurality of colorless and transparent solid particles are placed in a sample box. The upper end of the cartridge is not closed.
A water tank is filled with a transparent solution containing tracer particles, i.e., a mixed solution.
The position of the plexiglas barrel I-I and the plexiglas barrel II-I is fixed. And closing the valve I and the valve II.
And 2, starting a water pump, and injecting the mixed liquid in the bucket into the organic glass drums I-II through the silica gel hose I and the silica gel hose II.
And 3, opening a valve I after the organic glass drum I-II is filled with the mixed liquid and overflows to the organic glass drum I-I. The mixture was slowly poured into the cartridge through the silica gel tube IV and mixed with the colorless transparent solid particles, during which the sample was gently stirred with a glass rod to expel air bubbles.
And (4) when the liquid level of the mixed liquid of the sample box to be tested approaches the opening at the top end of the sample box, temporarily closing the valve I and sealing the sample box by using the sealing plate.
And 5, simultaneously opening the valve I and the valve II, enabling the mixed liquid to flow into the organic glass barrel II-II through the silica gel hose VI after the sample box is filled with the mixed liquid, enabling the mixed liquid to flow into the organic glass barrel II-I after the organic glass barrel II-II is filled with the mixed liquid, and then enabling the mixed liquid to flow back into the water barrel through the silica gel hose V.
Obtaining a predetermined head of mixed liquid by adjusting the relative heights of the plexiglass barrels I-I and II-I.
7) And after the circulation of the mixed liquid is stable, opening a laser lamp holder, and enabling the laser to penetrate through the sample box to form a laser plane in the sample.
And 8, adjusting the position of the digital single lens reflex to capture the image.
And 9, obtaining a plurality of images by changing the positions of the laser light and the digital single lens reflex for a plurality of times.
Processing and data analysis of the image.
Changing the gradation and compactness of the sample in the sample box, changing the water head and repeating the process.
The technical effect of the present invention is undoubted.
Drawings
FIG. 1 is a flow chart of the method of the present invention;
FIG. 2 is a schematic view of a sample solution circulation system of the apparatus of the present invention;
FIG. 3 is a schematic view of a cartridge;
FIG. 4 is an original image collected by a single lens reflex;
FIG. 5 is a binarized image of particles identified when the threshold value was taken at 0.05;
FIG. 6 is a binarized image of particles identified when the threshold value is taken at 0.1;
FIG. 7 is a binarized image of particles identified when the threshold value was taken at 0.15;
FIG. 8 is a binarized image of particles identified using a threshold obtained by the maximum between-class variance method;
FIG. 9 is a flow field diagram;
fig. 10 is a flow rate frequency histogram.
In the figure: the device comprises a sample box 1, an upstream water head applying device 2, a sliding rod I201, a plexiglass barrel I-I202, a plexiglass barrel I-II203, a downstream water head applying device 3, a sliding rod II 301, a plexiglass barrel II-I302, a plexiglass barrel II-II303, a water barrel 4, a water pump 5, a silica gel hose I601, a silica gel hose II602, a silica gel hose III603, a silica gel hose IV604, a valve I6041, a silica gel hose V605, a silica gel hose VI606, a valve II6061 and a laser lamp head 7.
Detailed Description
The present invention is further illustrated by the following examples, but it should not be construed that the scope of the above-described subject matter is limited to the following examples. Various substitutions and alterations can be made without departing from the technical idea of the invention and the scope of the invention is covered by the present invention according to the common technical knowledge and the conventional means in the field.
Example 1:
a device for testing the flow characteristics of pore liquid in a porous medium is characterized by mainly comprising a sample box 1, an upstream water head applying device 2, a downstream water head applying device 3, a water barrel 4, a 375 water pump 5, a digital single lens reflex, a laser lamp holder 7 and a plurality of silica gel hoses 6.
The side wall of the sample box 1 is made of ultra-white glass, the lower bottom of the sample box is sealed and placed on an experiment platform, and the upper end of the sample box is open. The ultra-white glass sample box is 200mm high, and the cross section size is 100 x 100 mm. The inner part is filled with artificial transparent porous medium. The upper end and the lower end of the glass are respectively plugged by an organic glass top plate and an organic glass bottom plate, wherein the organic glass bottom plate is fixedly bonded with the side surface of the ultra-white glass in advance. The upper end opening of the sample box 1 can be blocked by a sealing plate. The sealing plate is an organic glass top plate, the organic glass top plate and the organic glass bottom plate are 140-140 mm square, the middle of the sealing plate is provided with a round hole A and a round hole B with the diameter of 10mm, and the round holes are connected with a silica gel hose of the liquid circulation system; the four corners of the top plate and the bottom plate are respectively provided with a pin hole with the diameter of 6mm, a screw rod is inserted into the pin hole, two ends of the screw rod are fixed by screw caps, and the function of sealing the sample box is achieved through locking the screw caps.
The upstream waterhead application device 2 comprises a sliding bar I201, a plexiglas barrel I-I202 and a plexiglas barrel I-II 203. The lower end of the sliding rod I201 is fixed on the experiment platform. The organic glass barrel I-I202 is hung on the sliding rod I201 through a sliding block. The plastic drum I-II203 is located within the plastic drum I-I202. The external diameter of the cross section of the cylindrical barrel is 110mm, the wall thickness of the organic glass is 5mm, the height of the organic glass is 100mm, the thickness of the lower bottom of the organic glass is 5mm, and the organic glass has no upper bottom; the outer diameter of the cross section of the inner round barrel is 60mm, the wall thickness of organic glass is 5mm, the height of the organic glass is 70mm, and the upper end of the organic glass is open.
The water pump 5 pumps the liquid in the water barrel 4 through the silica gel hose I601 and then conveys the liquid to the organic glass drums I-II203 through the silica gel hose II 602. After the drum I-II203 is filled with liquid, the liquid spills into the drum I-I202. The water outlet at the lower end of the organic glass cylinder I-I202 is connected into the water barrel 4 through the silica gel hose III603, so that the liquid in the organic glass cylinder I-I202 flows back to the water barrel 4.
The water outlet at the lower end of the organic glass drum I-II203 is connected to the water inlet at the bottom of the sample box 1 through a silica gel hose IV 604. The silicone tube IV604 penetrates the bottom of the plexiglas barrel I-I202. And a valve I6041 is arranged on the silica gel hose IV 604.
The downstream water head applying device 3 comprises a sliding rod II 301, a plexiglas barrel II-I302 and a plexiglas barrel II-II 303.
The lower end of the sliding rod II 301 is fixed on the experiment platform. The organic glass barrel II-I302 is hung on the sliding rod II 301 through a sliding block. The plexiglas barrel II-II303 is located in the plexiglas barrel II-I302. The sealing plate configured in the sample box 1 has a water outlet, and the water outlet is connected into the organic glass drum II-II303 through a silica gel hose VI 606. The silicone hose VI606 has a valve II 6061. After the liquid in the plexiglass cylinder II-II303 is filled, the liquid is filled into the plexiglass cylinder II-I302. The water outlet at the lower end of the organic glass barrel II-I302 is connected into the water barrel 4 through a silica gel hose V605. The bottom surfaces of the inner and outer drums are connected, and the centers of the cross sections are superposed.
The height of the organic glass cylinder I-I202 is adjusted through the sliding block on the sliding rod I201. The height of the organic glass barrel II-I302 is adjusted through the sliding block on the sliding rod II 301. The bottom of the plexiglass drum I-II203 is always higher than the bottom of the plexiglass drum II-II 303.
The laser lamp head 7 is positioned at one side of the sample box 1 and emits a laser plane to the sample box 1. In the embodiment, the 532nm150mw high-stability temperature-control green laser module is selected to comprise a linear green laser lamp head, a control box, a universal bracket and a 220V-to-DC 12V2A waterproof power supply.
The laser lamp holder is characterized in that: the length, width and height dimensions are 30 x 45mm, the tail part is provided with a radiating groove and a fan, and the fan can be automatically started to cool when reaching a certain temperature. The power is 150mW, the wavelength is 532nm, the light spot mode is a word line, and laser planes are formed in a sample when laser passes through the transparent porous medium. The universal support is used for fixing the laser lamp head and is characterized in that the position of the lamp head can be adjusted in any direction in a rotating mode. The XY axis linear optical axis guide rail fine adjustment table (hereinafter referred to as a guide rail) has a stroke of 60 x 60mm, and the feeding amount of one circle of stainless steel wire rods is 0.7 mm.
During the experiment, universal bracket in the green laser module is fixed with the laser lamp holder, and is fixed with the guide rail down, confirms the laser face position through adjusting the guide rail.
The digital single lens reflex camera is aligned with the sample box 1 for shooting, and the axis of the lens is vertical to the laser plane. The digital single lens reflex adopts a PENTAX digital single lens reflex, and is provided with a tripod and a timing shutter release.
Example 2:
an experimental method for testing the flow characteristics of pore liquid in a porous medium based on the device in embodiment 1 is characterized by comprising the following steps:
preparing colorless transparent solid particles (with different particle diameters of 6-13 mm) and transparent solution, wherein the refractive indexes of the colorless transparent solid particles and the transparent solution are the same, so that after the two materials are mixed, incident light rarely or even does not refract or scatter when passing through a solid-liquid interface, thereby reducing the energy loss of the light during the transmission, and enabling the artificial mixed medium system to show transparent characteristics relative to the light with specific frequency.
And preparing tracer particles with different refractive indexes from the colorless transparent solid particles. The requirements for the tracer particles are: 1) the density of the solution is close to that of the solution, and the particle size is small so as to have better following performance; 2) under the irradiation of laser, the film has enough astigmatism and is easy to form images when photos are taken.
According to the set gradation and compactness, a plurality of colorless and transparent solid particles are placed in the sample box 1. The upper end of the cartridge 1 is not closed.
A clear solution (sucrose solution with 37.5% of mass fraction) containing a proper amount of tracer particles is filled in the water barrel 4, namely a mixed solution.
The position of the plexiglass cylinder I-I202 and the plexiglass cylinder II-I302 are fixed. Valve I6041 and valve II6061 are closed.
Starting the water pump 5, and injecting the mixed liquid in the water barrel 4 into the organic glass drums I-II203 through the silica gel hose I601 and the silica gel hose II 602.
Opening a valve I6041 after the mixed liquid fills the organic glass drum I-II203 and overflows to the organic glass drum I-I202. The mixture was slowly poured into the cartridge 1 through the silica gel tube IV604 and mixed with the colorless transparent solid particles, during which the sample was gently stirred with a glass rod to expel air bubbles.
When the liquid level of the mixed solution in the sample cell 1 reaches the top opening of the sample cell 1 (about 1cm), the valve I6041 is temporarily closed, and the sample cell 1 is sealed with the sealing plate.
Opening a valve I6041 and a valve II6061 simultaneously, enabling the mixed liquid to flow into the organic glass drum II-II303 through a silica gel hose VI606 after the sample box 1 is filled with the mixed liquid, enabling the mixed liquid to flow into the organic glass drum II-I302 after the organic glass drum II-II303 is filled with the mixed liquid, and then enabling the mixed liquid to flow back into the water barrel 4 through a silica gel hose V605.
So far, the whole process forms a mixed liquid circulating system, and it is worth noting that the upper bottom of the drum II of the upstream water head applying device is higher than that of the drum II of the downstream water head applying device, so that a water head difference can be formed.
A predetermined mixed liquid head is achieved by adjusting the relative height between the plexiglass barrels I-I202 and II-I302.
And 7, after the circulation of the mixed liquid is stable, opening a laser lamp holder 7, enabling laser to penetrate through the sample box 1 to form a green laser surface in the sample, and adjusting the laser surface to a proper position through a guide rail.
And 8, adjusting the position of the digital single lens reflex to capture the image.
The height of the camera is adjusted through the tripod, the camera is perpendicular to the laser surface, the height of the lens is as flat as possible with the middle of the laser surface, and the image is captured through the camera by utilizing the shutter release. The exposure time should be as short as possible during shooting to ensure that the particles in question are sufficiently large in the two adjacent frames of images.
And 9, obtaining a plurality of images by changing the positions of the laser light and the digital single lens reflex for a plurality of times.
Processing and data analysis of the image.
In the step 10, the image processing and data analysis mainly comprises image gray level binarization, tracing particle shape and particle size identification and flow rate statistics. In image processing, the selection of threshold is very critical, a low threshold will generate false edges, and a high threshold will cause some real edges to be lost.
After image acquisition, firstly selecting a proper threshold value to carry out image gray level binarization, removing uneven background brightness and deleting noise particles, and then carrying out morphological on-off operation to repair the image. Each pixel of the image is represented by an 8-bit binary number, i.e. of 256 orders of magnitude, each corresponding to a grey scale. In 0-255 levels, a gray level (namely a threshold) is required to be selected from the levels to divide the pixel set, and the level smaller than the gray level is set as 0 and is judged as a trace particle; a setting greater than this gray level is 255, representing a background or other object. Thus, when the image is further processed, the multi-level value of the pixel is no longer involved, and the image property is only related to the position of the point with a pixel value of 0 or 255.
After the binarization processing, the position coordinates of the pixels determined as trace particles are read, and the particle diameter is calculated according to the number of the pixels. And calculating the centroid position of each tracer particle for subsequent particle matching, and further calculating the displacement of the tracer particle.
The particle displacement obtained by programming calculation is pixel-based, the size of each pixel point is calculated according to the size of an image acquisition window, further the actual displacement is obtained, and then the actual displacement is divided by the time interval between two adjacent frames of images, so that the particle speed can be calculated.
Further, image processing and data analysis mainly comprise image gray level binarization, tracing particle shape and particle size identification and flow rate statistics. In image processing, the selection of threshold is very critical, a low threshold will generate false edges, and a high threshold will cause some real edges to be lost. Fig. 5 to 7 show the binary image contrast of the particles identified when the image threshold values are 0.05, 0.1, and 0.15, respectively. Fig. 8 shows the binary image contrast of the identified particles when the threshold value obtained by the maximum inter-class variance method is used. Fig. 9 is a trace particle flow field diagram, and fig. 10 is a velocity frequency histogram.
Changing the sample gradation and compactness in the sample box 1, changing the water head and repeating the process.
Claims (1)
1. The test method for testing the flow characteristic of the pore liquid in the porous medium is characterized in that a device for testing the flow characteristic of the pore liquid in the porous medium mainly comprises a sample box (1), an upstream water head applying device (2), a downstream water head applying device (3), a water barrel (4), a water pump (5), a digital single lens reflex camera, a laser lamp holder (7) and a plurality of silica gel hoses;
the side wall of the sample box (1) is made of ultra-white glass, the lower bottom of the sample box is sealed and placed on an experiment platform, and the upper end of the sample box is open; the upper end opening of the sample box (1) can be blocked by a sealing plate;
the upstream water head applying device (2) comprises a sliding rod I (201), a plexiglas barrel I-I (202) and a plexiglas barrel I-II (203); the lower end of the sliding rod I (201) is fixed on an experiment platform; the organic glass barrel I-I (202) is hung on the sliding rod I (201) through a sliding block; the plexiglass drum I-II (203) is located in the plexiglass drum I-I (202);
the water pump (5) pumps liquid in the water barrel (4) through the silica gel hose I (601), and then the liquid is conveyed into the organic glass drum I-II (203) through the silica gel hose II (602); after the organic glass drum I-II (203) is filled with liquid, the liquid overflows into the organic glass drum I-I (202); a water outlet at the lower end of the organic glass barrel I-I (202) is connected into the water barrel (4) through a silica gel hose III (603), so that liquid in the organic glass barrel I-I (202) flows back to the water barrel (4);
a water outlet at the lower end of the organic glass drum I-II (203) is connected to a water inlet at the bottom of the sample box (1) through a silica gel hose IV (604); the silica gel hose IV (604) penetrates through the bottom of the organic glass cylinder I-I (202); a valve I (6041) is arranged on the silica gel hose IV (604);
the downstream water head applying device (3) comprises a sliding rod II (301), a plexiglass cylinder II-I (302) and a plexiglass cylinder II-II (303);
the lower end of the sliding rod II (301) is fixed on the experiment platform; the organic glass barrel II-I (302) is hung on the sliding rod II (301) through a sliding block; the organic glass barrel II-II (303) is positioned in the organic glass barrel II-I (302); the sealing plate configured on the sample box (1) is provided with a water outlet, and the water outlet is connected into an organic glass drum II-II (303) through a silica gel hose VI (606); the silica gel hose VI (606) is provided with a valve II (6061); after the liquid in the organic glass cylinder II-II (303) is filled, the liquid is filled into the organic glass cylinder II-I (302); a water outlet at the lower end of the organic glass barrel II-I (302) is connected into the water barrel (4) through a silica gel hose V (605);
the height of the organic glass drum I-I (202) is adjusted through a sliding block on the sliding rod I (201); the height of the organic glass barrel II-I (302) is adjusted through the sliding block on the sliding rod II (301); the bottom of the organic glass barrel I-II (203) is always higher than that of the organic glass barrel II-II (303);
the laser lamp holder (7) is positioned on one side of the sample box (1) and emits a laser surface to the sample box (1); the digital single lens reflex camera is aligned with the sample box (1) for shooting, and the axis of the lens is vertical to the laser plane;
the test method for testing the flow characteristics of pore liquid in the porous medium comprises the following steps:
preparing colorless transparent solid particles and transparent solution, wherein the refractive indexes of the colorless transparent solid particles and the transparent solution are the same; preparing tracer particles;
placing a plurality of colorless transparent solid particles into a sample box (1) according to the set gradation and compactness;
a water barrel (4) is filled with transparent solution containing trace particles, namely mixed solution;
fixing the positions of the organic glass barrel I-I (202) and the organic glass barrel II-I (302); closing valve I (6041) and valve II (6061);
starting a water pump (5), and injecting the mixed liquid in the water bucket (4) into an organic glass drum I-II (203) through a silica gel hose I (601) and a silica gel hose II (602);
opening a valve I (6041) after the organic glass drum I-II (203) is filled with the mixed liquid and overflows to the organic glass drum I-I (202); the mixed liquid is slowly injected into the sample box (1) through a silica gel hose IV (604) and is mixed with colorless transparent solid particles, and in the process, a glass rod is used for gently stirring the sample to discharge air bubbles;
temporarily closing a valve I (6041) when the liquid level of the mixed liquid of the sample box (1) approaches the top opening of the sample box (1);
opening a valve I (6041) and a valve II (6061) simultaneously, enabling the mixed liquid to flow into an organic glass drum II-II (303) through a silica gel hose VI (606) after filling the sample box (1), enabling the mixed liquid to flow into the organic glass drum II-I (302) after filling the organic glass drum II-II (303), and then enabling the mixed liquid to flow back into the water barrel (4) through a silica gel hose V (605);
obtaining a predetermined mixed liquid head by adjusting the relative height between the plexiglass barrels I-I (202) and II-I (302);
after the circulation of the mixed liquid is stable, opening a laser lamp holder (7) to enable laser to penetrate through the sample box (1) to form a laser surface in the sample;
adjusting the position of the digital single lens reflex camera to capture an image;
obtaining a plurality of images by changing the positions of the laser light and the digital single lens reflex for a plurality of times;
processing and data analysis are carried out on the image;
10.1, selecting a threshold value to carry out image gray level binarization processing, and carrying out morphological opening and closing operation to repair an image; setting a pixel set smaller than a threshold value as 0, and judging as a trace particle; the set of pixels greater than the threshold is set to 255 and considered as a background or other object;
reading the position coordinates of the pixels judged as the trace particles, and calculating the particle diameter and the centroid position of each trace particle according to the pixel value;
taking a pixel as a unit, and obtaining a displacement vector of the particle through programming calculation; calculating the size of each pixel point according to the size of the image acquisition window so as to obtain actual displacement, and calculating the speed of particles according to the time interval between two adjacent frames of images on the basis;
changing the sample gradation and the compactness in the sample box (1), changing the water head and repeating the process.
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| CN112284982B (en) * | 2020-11-23 | 2024-05-14 | 西南石油大学 | Evaluation device for spreading and plugging performance of plugging agent on porous medium air-water interface |
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