Visual research test system and method for water-sand two-phase flow characteristics in double media

Abstract

The invention discloses a visual research test system and method for water-sand two-phase flow characteristics in double media. The system comprises a double-medium model, a PIV subsystem, a water supply subsystem and a particle conveying subsystem. The dual-medium model is of a transparent structure, and a 3D printed target construction stratum structure is loaded in the dual-medium model; the water supply subsystem comprises a water supply tank; the water supply tank is connected with the dual-medium model through a water supply pipeline; the particle conveying subsystem comprises a particle storage box and a particle nozzle, one end of the particle nozzle is communicated with the particle storage box, the other end of the particle nozzle is connected with the dual-medium model, and sand particles and dyeing particles are loaded in the particle storage box; the water supply subsystem and the particle conveying subsystem are located on the same side of the dual-medium model, the PIV subsystem comprises a first camera, a laser and a sheet light source, and the laser and the light source are located above the dual-medium model. The invention aims to truly simulate the flow characteristics of the water-sand two-phase flow under a dual-medium complex pore structure close to the actual stratum.

Description

Technical Field

[0001] The present invention relates to the technical field of test devices, and particularly to a test system and method for visual research on the characteristics of water-sand two-phase flow in dual media. Background Technique

[0002] At present, during the tunnel construction process, in areas where dual media are widely distributed, the occurrence of tunnel water inrush is often caused under the influence of stress disturbance. During the evolution process of water inrush, the flow of fluid and fine particles exhibits two-phase flow characteristics, and the interaction between water and sand will lead to complex phenomena such as permeability change, uneven flow velocity, and increased fluid resistance, thereby triggering concurrent engineering geological problems such as formation deformation. Furthermore, in the research of tunnels and underground engineering, through various visualization means in the dual-media water-sand two-phase flow visualization test device, it can help visually observe the interaction between water flow and soil particles, the sedimentation and resuspension characteristics of soil particles, and the migration and distribution laws under complex geological conditions, thereby improving the research on the movement characteristics of water-sand two-phase flow during the evolution process of tunnel water inrush, providing important scientific basis and test data support for sediment control, particle transportation, structural design, equipment protection, and environmental monitoring during tunnel construction, and also providing important references for related engineering design and optimization.

[0003] The existing invention patent with the patent number CN105842140A discloses a water-sand seepage experiment system for fractured rock masses, which conducts experiments on the liquid-solid coupling seepage of water-sand two-phase flow and can freely adjust the sand content ratio of the water-sand mixture, but it cannot achieve continuous sand supply, resulting in the inability to simulate the situation of a large amount of sand grain seepage. And the existing invention patent with the publication number CN105628590A discloses a test device for water-sand two-phase seepage in fractured rock, although it discloses multiple ways of adding sand, its structure is complex and the mixing is uneven, resulting in a large error in the sand-water mixing concentration. Summary of the Invention

[0004] The main object of the present invention is to provide a test system and method for visual research on the characteristics of water-sand two-phase flow in dual media, aiming to solve the technical problem that the existing test devices cannot efficiently simulate the water-sand two-phase flow characteristics of dual media.

[0005] To achieve the above object, the present invention provides a test system for visual research on the characteristics of water-sand two-phase flow in dual media, and the device includes a dual-media model, a PIV subsystem, a water supply subsystem, and a particle transportation subsystem;

[0006] The dual-media model is of a transparent structure and internally loaded with a 3D-printed target construction formation structure;

[0007] The water supply subsystem includes a water supply tank, and the water supply tank is connected to the dual-media model through a water supply pipeline;

[0008] The particle delivery subsystem includes a particle storage tank and a particle nozzle. One end of the particle nozzle is connected to the particle storage tank, and the other end is connected to the dual-medium model. The particle storage tank is loaded with uniformly mixed sand grains and dyed particles of various sizes.

[0009] The water supply subsystem and the particle delivery subsystem are located on the same side of the dual-medium model to simulate the influx of sand and water into the target construction formation structure.

[0010] The PIV subsystem includes a first camera, a laser, and a sheet light source. The laser and the light source component are located above the dual-medium model. The laser is used to provide light for the dyed particles, the sheet light source is used to provide illumination for the dyed particles, and the first camera is used to intuitively display the operation of the sand and water influx into the target construction formation structure by photographing the position change of the dyed particles after the action of the laser pulse.

[0011] Optionally, the device further includes a particle separation tank, which is connected to the other side of the dual-medium model opposite to the water supply subsystem and the particle delivery subsystem to collect the sand grains and dyed particles discharged from the dual-medium model.

[0012] Optionally, the particle storage tank is further connected to a first pressure pump, and the first pressure pump is used to pump the sand grains in the particle storage tank into the particle nozzle.

[0013] Optionally, the injection angle of the particle nozzle is 30 to 60 degrees.

[0014] Optionally, the water supply tank is further connected to a second pressure pump and a frequency converter respectively, and the frequency converter is used to adjust the water flow rate and pressure output from the water supply tank.

[0015] Optionally, the dual-medium model is placed on a corresponding test bench, and the test bench is provided with multiple threaded support columns, and the multiple threaded support columns are used to adjust the inclination angle of the dual-medium model.

[0016] Optionally, the particle separation tank includes an upper particle filtration area and a lower water storage area, and a waste water outlet is further connected to the side wall of the water storage area.

[0017] Optionally, the particle filtration area includes multiple layers of sieves, and the filtration pore sizes of each layer of sieves decrease sequentially from top to bottom.

[0018] Optionally, a calibration object is further placed on the upper surface of the dual-medium model, and the calibration object is used to assist in adjusting the laser light source plane of the laser and the camera illumination plane to be perpendicular.

[0019] In addition, to achieve the above object, the present invention also provides a test method for a test system for visualizing the characteristics of water-sand two-phase flow in the above-mentioned dual medium, and the test method includes the following steps:

[0020] Step 1, preliminary preparation, including placing the required particles in the particle storage tank, adding dyed polystyrene fine particles to the water supply tank for the operation of the PIV subsystem, adjusting the threaded support columns on both sides of the test bench to the test requirements, installing a particle sensor and connecting it to the second computer so that the second computer can obtain the data of the particle sensor;

[0021] Step 2, PIV subsystem calibration, that is, placing a preset calibration object on the upper surface of the dual medium model and adjusting the position and angle in the PIV subsystem to make the laser plane uniform and perpendicular to the camera lens;

[0022] Step 3, turn on the second pressure pump and open the switch of the water supply tank to start supplying the test-set water flow conditions to the inside of the dual medium model 8;

[0023] Step 4, after the water flow is stable, turn on the first pressure pump to transport the particles stored in the particle storage bin to the particle nozzle and transport the particles into the dual medium model at a preset angle and speed;

[0024] Step 5, when starting to transport particles into the dual medium model, turn on the second camera to visually record the movement state of the particles during the entire test process in the dual medium model, and turn on the first camera to cooperate with the other components of the PIV subsystem to record the evolution of the flow field during the entire test process;

[0025] Step 6, stop the test after collecting a preset amount of data, and sequentially turn off the first pressure pump, the particle storage bin, the second pressure pump, the water supply tank, and the other PIV subsystems;

[0026] Step 7, obtain the residual amounts of particles with different particle sizes from the particle separation tank, dry the particles in different particle size ranges, weigh them, and record them for subsequent data analysis;

[0027] Step 8, analyze the data recorded during the test process by the computer system and the second camera to obtain the deposition and resuspension characteristics and migration and distribution laws of sand grains in the dual medium under different water flow conditions.

[0028] Beneficial effects:

[0029] The present invention adopts 3D modeling and printing technology, constructs a dual-medium model using transparent materials, and can accurately simulate the pore structure of the actual formation and the complex fracture network. Compared with the traditional simplified model, this modeling method can more realistically restore the complexity of the rock mass, such as irregular fractures and microscopic pore structures, improving the accuracy and referenceability of the test. In addition, combined with the Particle Image Velocimetry (PIV) system, through the coordinated action of a high-precision camera, a laser, and a sheet light source, the flow field evolution characteristics of the water-sand two-phase flow can be measured with high precision. The PIV subsystem can not only accurately capture the trajectories and interactions of particles in the water-sand flow, but also systematically analyze the evolution process of the flow field as a whole. Compared with traditional measurement methods, the PIV subsystem provides higher measurement accuracy, significantly improving the visualization of the flow characteristics and hydrodynamic behavior, thus providing more comprehensive and accurate technical support for in-depth analysis of the flow characteristics of the water-sand two-phase flow. Furthermore, the present invention can truly simulate the flow characteristics of the water-sand two-phase flow under the complex pore structure of the dual medium close to the actual formation, and study the interaction between water flow and soil particles, the sedimentation and resuspension characteristics, and the migration and distribution laws of soil particles under different particle concentrations, dual-medium structures, and water flow conditions. The visualization part of the device provides an intuitive observation means, which can clearly display the evolution laws of the particle transport path, sedimentation, and restart, and at the same time collect multi-dimensional parameters such as particle concentration and flow field during the evolution process, providing important scientific basis and experimental data support for sediment control and particle transport in tunnel construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0031] Figure 1 It is a schematic structural diagram of an embodiment of a test system for visualizing the characteristics of water-sand two-phase flow in a dual medium according to the present invention;

[0032] Figure 2 is Figure 1 a schematic diagram of the shown particle separation tank;

[0033] Figure 3 is Figure 1 a schematic diagram of the shown particle nozzle.

[0034] Explanation of the reference numerals in the drawings:

[0035] 101 First computer, 102 Second computer, 201 First pressure pump, 202 Second pressure pump, 3 Frequency converter, 4 Particle storage tank, 5 Water supply tank, 601 First electromagnetic flowmeter, 602 First electromagnetic flowmeter, 7 Particle nozzle, 8 Dual-medium model, 9 First camera, 10 Laser, 11 Sheet light source, 12 Test bench, 13 Threaded support column, 14 Fixed iron frame, 1501 First particle sensor, 1502 Second particle sensor, 1503 Third particle sensor, 16 Particle separation tank, 17 Waste water outlet; 18 Second camera.

[0036] The realization, functional features and advantages of the present invention will be further described in conjunction with the embodiments with reference to the accompanying drawings. Specific embodiments

[0037] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present invention.

[0038] It should be noted that all the directional indications (such as up, down...) in the embodiments of the present invention are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0039] In addition, the descriptions such as "first" and "second" in the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features.

[0040] Moreover, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0041] See Figures 1 to 3 , the present invention provides a structural schematic diagram of an embodiment of a test system for visualizing the characteristics of water-sand two-phase flow in a dual medium. Among them, the device includes a dual-medium model 8, a PIV subsystem, a water supply subsystem, and a particle transport subsystem.

[0042] Among them, the dual-medium model 8 is a transparent structure and is internally loaded with the target construction formation structure. Generally, the target construction formation structure is printed using a 3D modeling and printing technique with a transparent material according to the condition parameters of the actual construction formation. Compared with the traditional simplified model, it can most accurately restore the actual formation conditions and pore states, ensuring the accuracy and referenceability of the experiment. At the same time, considering the need to detect the particle concentration in the experiment, positions for sensors need to be reserved in the 3D modeling. Preferably, the first particle sensor 1501, the second particle sensor 1502, and the third particle sensor 1503 are usually arranged in the upper, middle, and lower parts of the flow field observation position to analyze the interaction between the two.

[0043] And the water supply subsystem includes a water supply tank 5, and the water supply tank 5 is connected to the dual-medium model 8 through a water supply pipeline; the particle conveying subsystem includes a particle storage tank 4 and a particle nozzle 7. One end of the particle nozzle 7 is communicated with the particle storage tank 4, and the other end is connected to the dual-medium model 8. The particle storage tank 4 is loaded with uniformly mixed sand grains and dyed particles of various sizes; the water supply subsystem and the particle conveying subsystem are located on the same side of the dual-medium model 8 to simulate the influx of sand and water into the target construction formation structure.

[0044] Preferably, the particle storage tank 4 is also connected to a first pressure pump 201. The first pressure pump 201 is used to pump the sand grains in the particle storage tank 4 into the particle nozzle 7, and the spraying angle range of the particle nozzle 7 is 30 to 60 degrees, specifically as Figure 3 shown. Therefore, by adjusting the spraying range of the particle nozzle 7, the initial motion states of particles under various working conditions are simulated to meet different test requirements.

[0045] Preferably, the water supply tank 5 is also respectively connected to a second pressure pump 202 and a frequency converter 3. The frequency converter 3 is used to adjust the water flow rate and pressure output from the water supply tank 5, and the precise control of the water flow rate is achieved by adjusting the rotation speed of the second pressure pump 202, thereby meeting the test requirements.

[0046] Furthermore, the frequency converter 3 and the particle storage tank 4 are also electrically connected to a first computer 101, thereby realizing the intelligent setting of the output flow rate and flow velocity of sand and water.

[0047] Furthermore, a first electromagnetic flowmeter 601 is also provided in the water supply pipeline, and thus the flow rate is monitored through the first electromagnetic flowmeter 601 to achieve real-time monitoring of the water flow rate.

[0048] Furthermore, the PIV subsystem includes a first camera 9, a laser 10, and a sheet light source 11. The laser 10 and the light source component 11 are located above the dual-medium model 8. The laser 10 is used to provide a light source for the dye particles, the sheet light source 11 is used to provide illumination for the dye particles, and the first camera 9 is used to visually display the operation of the sand-water influx into the target construction formation structure by photographing the position change of the dye particles after the action of laser pulses. Among them, the laser 10 usually uses double-pulse laser to provide a light source for the dye particles in the flow field. The laser beam forms a thin light layer in the fluid, exciting the dye particles in the fluid. The main function of the sheet light source 11 is to provide uniform illumination for the dye particles in the flow field to ensure that the displacement of the dye particles between two laser pulses can be accurately captured and analyzed. And the first camera 9 captures the position change of the dye particles by photographing the flow field images after the action of two laser pulses. Preferably, in order to distinguish the dye particles used for the operation of the PIV subsystem and the sand grains used for the test, polystyrene that can move with the flow of the fluid and whose particle size, density, etc. are suitable for the fluid is selected as the dye particles for the operation of the PIV subsystem.

[0049] Furthermore, the first camera 9 is a high-precision camera.

[0050] Furthermore, the device further includes a particle separation tank 16. The particle separation tank 16 is connected to the other side of the dual-medium model 8 opposite to the water supply subsystem and the particle conveying subsystem. The particle separation tank 16 is connected to the dual-medium model 8 through a discharge pipeline, and a second electromagnetic flowmeter 602 is also connected in the discharge pipeline. The outlet of the discharge pipeline extends deep into the particle separation tank 16. Furthermore, the residual amount of particles with different particle sizes can be visually observed in the particle separation tank 16. After drying the particles in different particle size ranges, they are weighed and recorded for subsequent data analysis. Preferably, the particle separation tank 16 includes a particle filtration area in the upper part and a water storage area in the lower part. A waste water outlet 17 is also connected to the side wall of the water storage area, and when the water storage area is full, it can be discharged through the waste water outlet 17. And the particle filtration area includes multiple layers of sieves. As Figure 2 shown, the filtration pore diameters of each layer of sieve decrease sequentially from top to bottom, and thus the appropriate sieve can be freely selected according to the actual conditions.

[0051] Further, the dual-medium model 8 is placed on a corresponding test bench 12. The test bench 12 is provided with a plurality of threaded support columns 13. Among them, the height of the threaded support columns 13 is adjustable. Further, the plurality of threaded support columns 13 are used to adjust the inclination angle of the dual-medium model 8 to simulate the construction stratum structures with different slopes. Preferably, the inclination angle is from -10 degrees to 10 degrees. Further, a plurality of fixed iron frames 14 are additionally arranged outside the dual-medium model 8. The plurality of fixed iron frames 14 are mainly used to fix the medium model to ensure stability during the test. Preferably, the fixed iron frames 14 are connected to the corresponding threaded support columns 13.

[0052] Further, to ensure that the laser plane irradiates the test area correctly and the laser plane is accurately presented in the image, geometric calibration of the laser light source is required. Therefore, a calibration object is also placed on the upper surface of the dual-medium model 8. The calibration object is used to assist in adjusting the laser light source plane of the laser 10 and the irradiation plane of the camera 9 to be perpendicular.

[0053] Further, the sensors arranged in the dual-medium model 8 are also electrically connected to the second computer 102 to obtain the test data during the test in real time.

[0054] Further, the device further includes a second camera 18. The second camera 18 can clearly capture the flow behavior of the particles in the medium to ensure the visualization of the dynamic process. It can combine with the data of the sensor 15 to feedback the test situation in real time and record the behavior characteristics of the particles in different types of media. Preferably, the second camera 18 is an industrial-grade camera.

[0055] Further, to better illustrate the effect of the system of the present invention, the following describes it through the specific test steps of the system:

[0056] Preparations: Place the particles required for the test in the particle storage box 4 and keep them dry; add the dyed polystyrene fine particles to the water supply tank 5 for the operation of the PIV subsystem. Adjust the threaded support columns 13 on both sides of the test bench 12 according to the test design so that various parameters of the dual-medium model 8 meet the test requirements. Install the particle sensors 15 at three positions and connect them to the second computer 102 for data transmission during the test.

[0057] Calibration of the PIV subsystem: During the operation of the PIV subsystem, place a calibration object with a known size, such as a glass plate or a transparent ruler with regular scales, in the test scene. Observe the positional relationship between the laser light plane and the calibration object, and ensure that the light plane irradiates correctly. By taking images at multiple different positions, check the shape of the laser plane in the images to ensure that the light plane is uniform and perpendicular to the camera lens. After calibration, keep the device in an always-on state.

[0058] Water supply step: Turn on the second pressure pump 202 and open the switch of the water supply tank 5 to start supplying the test-set water flow conditions into the dual-medium model 8. Monitor the flow rate through the first electromagnetic flowmeter 601 until the model is filled with water.

[0059] Particle transportation step: After the water flow stabilizes, turn on the first pressure pump 201 to transport the particles stored in the particle storage bin 4 to the particle nozzle 7, and transport the particles into the model at a preset angle and speed.

[0060] Data acquisition: When starting to transport particles into the model, turn on the second camera 18 to visually record the motion state of the particles during the entire test process in the model; turn on the first camera 9 to cooperate with the other PIV subsystem components to record the evolution of the flow field during the entire test process. Stop the test after sufficient data is collected, and then turn off the first pressure pump 201, the particle storage bin 4, the second pressure pump 202, the water supply tank 5, and the other PIV subsystem components in sequence.

[0061] Particle processing: The residual amounts of particles with different particle sizes can be visually observed in the particle separation tank 16. Dry the particles in different particle size ranges, weigh them, and record them for subsequent data analysis.

[0062] Finally, the computer system and the second camera 18 record the key behaviors during the test process, including the changes in the flow field and the data of the particle sensors. Combining subsequent data analysis and visualization means, accurately depict the deposition and resuspension characteristics, as well as the migration and distribution laws of sand grains in the dual medium under different water flow conditions, providing important technical support for the research on the characteristics of water-sand two-phase flow in multi-media and related engineering design and prevention. The computer system includes the first computer 101 and the second computer 102.

[0063] In the above embodiments, those skilled in the art can adopt the existing technology for software control. The present invention only relates to the structure of the test system for visualizing the characteristics of water-sand two-phase flow in the dual medium and their mutual connection relationships.

[0064] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made using the content of the specification and drawings of the present invention under the inventive concept of the present invention, or any direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A visual research test system for water-sand two-phase flow characteristics in dual media, characterized in that: The device comprises a dual medium model (8), a PIV subsystem, a water supply subsystem, and a particle transport subsystem; The dual medium model (8) is a transparent structure and contains a 3D printed target construction stratum structure; The water supply subsystem comprises a water supply tank (5), and the water supply tank (5) is connected to the dual medium model (8) through a water supply pipeline; The particle conveying subsystem comprises a particle storage box (4) and a particle nozzle (7), one end of the particle nozzle (7) is connected to the particle storage box (4), and the other end is connected to the dual medium model (8), and the particle storage box (4) is loaded with sand particles and dyeing particles of various sizes uniformly mixed; The water supply subsystem and the particle transport subsystem are located on the same side of the dual medium model (8) to simulate the influx of sand and water into the target construction stratum structure; The PIV subsystem comprises a first camera (9), a laser (10), and a light source sheet (11). The laser (10) and the light source element (11) are located above the dual medium model (8). The laser (10) is used to provide a light source for the dyed particles, and the light source sheet (11) is used to provide illumination for the dyed particles. The first camera (9) is used to visually display the operation of sand and water flowing into the target construction stratum structure by photographing the position changes of the dyed particles after the action of the laser pulse.

2. The water-sand two-phase flow characteristics visualization research test system in dual media according to claim 1 is characterized in that: The device also includes a particle separation tank (16), which is located on the other side of the dual medium model (8) opposite to the water supply subsystem and the particle transport subsystem and is connected to collect sand particles and dye particles discharged from the dual medium model (8).

3. The water-sand two-phase flow characteristics visualization research test system in dual media according to claim 1 is characterized in that: The particle storage box (4) is also connected to a first pressure pump (201), and the first pressure pump (201) is used to blow the sand particles in the particle storage box (4) into the particle nozzle (7).

4. The water-sand two-phase flow characteristics visualization research and experimental system in dual media according to claim 1 is characterized in that: The spraying angle of the particle nozzle (7) is 30 to 60 degrees.

5. The water-sand two-phase flow characteristics visualization research and experimental system in dual media according to claim 1 is characterized in that: The water supply tank (5) is also connected to the second pressure pump (202) and the frequency converter (3) respectively. The frequency converter (3) is used to adjust the flow speed and pressure of water output from the water supply tank (5).

6. The water-sand two-phase flow characteristics visualization research and experimental system in dual media according to claim 1 is characterized in that: The dual medium model (8) is arranged on a corresponding test base (12), and the test base (12) is provided with a plurality of threaded support columns (13), and the plurality of threaded support columns (13) are used to adjust the inclination angle of the dual medium model (8).

7. The water-sand two-phase flow characteristics visualization research and experimental system in dual media according to claim 2 is characterized in that: The particle separation tank (16) comprises an upper particle filtering area and a lower water storage area, and the side wall of the water storage area is also connected to a wastewater outlet (17).

8. The water-sand two-phase flow characteristics visualization research and experimental system in dual media according to claim 7 is characterized in that: The particle filtering area includes multiple layers of screens, and the filtering apertures of each layer of screens decrease from top to bottom.

9. The visual research and experimental system for water-sand two-phase flow characteristics in dual media according to any one of claims 1 to 8, characterized in that: A calibration object is also placed on the upper surface of the dual medium model (8), and the calibration object is used to assist in adjusting the laser light source plane of the laser (10) and the irradiation plane of the camera (9) to be in a vertical state.

10. An experimental method for a visualization research experimental system for water-sand two-phase flow characteristics in dual media according to any one of claims 1 to 9, characterized in that: The test method comprises the following steps: Step 1, pre-preparation, including placing the particles required for the test in a particle storage box, adding dyed polystyrene fine particles in the water supply tank for the PIV subsystem to work, adjusting the threaded support columns on both sides of the test base to the test requirements, installing the particle sensor and connecting it to the second computer so that the second computer can obtain data from the particle sensor; Step 2, PIV subsystem calibration, that is, placing a preset calibration object on the upper surface of the dual medium model, and adjusting the position and angle in the PIV subsystem to make the laser plane uniform and perpendicular to the camera lens; Step 3, turning on the second pressure pump and turning on the switch of the water supply tank to start providing the water flow conditions set in the test to the inside of the dual medium model 8; Step 4, after the water flow is stable, the first pressure pump is turned on to transport the particles stored in the particle storage bin to the particle nozzle, and the particles are transported into the dual medium model at a preset angle and speed; Step 5, when the particles start to be transported into the dual medium model, the second camera is turned on to visually record the movement state of the particles in the dual medium model during the entire test process, and the first camera is turned on to cooperate with the remaining PIV subsystem components to record the flow field evolution during the entire test process; Step 6, after collecting a preset amount of data, stop the test and turn off the first pressure pump, the particle storage bin, the second pressure pump, the water supply tank and the remaining PIV subsystems in sequence; Step 7, obtaining the residual amount of particles of different particle sizes in the particle separation tank, and weighing and recording the particles of different particle size ranges after drying, so as to facilitate subsequent data analysis; Step 8, analyzing the data of the test process recorded by the computer system and the second camera to obtain the sedimentation and resuspension characteristics and migration and distribution patterns of sand particles in the dual medium under different water flow conditions.

Images