A method for simulating the transport characteristics of coarse particles in sediment-laden flow in a bifurcated pipeline

Abstract

The present invention relates to a method for simulating the transportation characteristics of coarse particles in sediment-laden flow in bifurcated pipelines, belonging to the field of hydraulic engineering, and its IPC international patent classification number is E02B 1 / 00. The hydraulic model adopted in the method of the present invention can quickly, conveniently and stably switch test conditions with different bifurcated pipeline angles, different overall inclination angles, and different pipeline inflow and outflow forms through an advance and retreat water tank system, a water diversion pipeline system, a coarse particle feeding port, a movable and telescopic support, etc. A sealed rectangular glass water tank is adopted to reduce the distortion of camera pictures caused by different refractive indexes of different materials such as plexiglass and water flow, and can improve the observation accuracy of a high-speed camera. Water can be recycled between the three groups of advance and retreat water tanks by using pipelines and valves to divert water back and forth between the advance and retreat water tanks, playing a role in saving water resources.

Description

Technical Field:

[0001] The present invention relates to a method for simulating the transport characteristics of coarse particles in sediment-laden flow in a bifurcated pipeline, belonging to the field of hydraulic engineering, and its IPC international patent classification number is E02B 1 / 00. Background Art:

[0002] According to the "Sediment Handbook" (edited by the Sediment Professional Committee of the China Hydraulic Engineering Society. Beijing: China Environmental Science Press, April 1992), particles with a particle size of 2 mm - 20 mm are called coarse particles. The engineering applications of the transport of coarse particles in sediment-laden flow in pipelines are extensive, such as sediment discharge in the dredging pipelines of rivers, lakes and reservoirs, lifting in deep-sea mining pipelines, and coal pipeline transportation. Compared with road, railway, waterway, and air transportation, pipeline transportation has the advantages of large transportation volume and low cost, and has become the fifth major transportation mode. Among them, the pipe network project composed of bifurcated pipelines has functions such as flow diversion and confluence, with a large transportation volume and a wide coverage area, and is widely used in the fields of dredging, mining, municipal engineering, and industry.

[0003] The most basic form of a bifurcated pipeline is a T-shaped or Y-shaped tee pipeline, which is widely used to change the movement direction of the transported medium to play the role of flow diversion or confluence. Existing scholars mainly carry out relevant research on the transport characteristics of bifurcated pipelines through numerical simulation and physical model tests. Numerical simulation is to construct a numerical calculation model for the transport of bifurcated pipelines through computer-related language programs. Physical model tests are to carry out research by building an experimental device of a physical bifurcated pipeline model. The existing model test devices mainly focus on the research of the transport process of water flow, gas and liquid two-phase flow in bifurcated pipelines.

[0004] The reservoirs, rivers and seabed sediments are complex, containing sediment particles of different particle sizes. In particular, the sediment deposits at the tail of mountain-type reservoirs and the fluctuating backwater areas contain many large-sized pebble coarse particles; during reservoir dredging, the Yellow River diversion project, and deep-sea mining, coarse particles enter the pipeline with high sediment-laden flow for transportation. In the coal pipeline project, a part of the coal is supplied to thermal power plants, and due to difficult dehydration, the particles are relatively coarse; another part is supplied to coal chemical plants, and the particles are very fine. Two kinds of materials with disconnected gradations are mixed with water and transported in the pipeline. Fine particles form high sediment-laden flow with water, together with coarse particles to form a three-phase mixture with disconnected gradation.

[0005] The following are the relevant literatures retrieved regarding the experimental devices for studying the transport characteristics of T-shaped or Y-shaped bifurcated pipelines, the selection of calculation parameters, and the post-processing methods of experimental data:

[0006] [1] Chen Weiye, Lü Hongxing, Shi Xi, et al. Experimental study on the local head loss coefficient of equal-diameter PVC tees [J]. Journal of Irrigation and Drainage, 2013, 32(01): 128 - 130.

[0007] [2] Shi Xi, Lü Hongxing, Zhu Delan, et al. Analysis of flow resistance and flow characteristics of PVC three-way pipes [J]. Transactions of the Chinese Society for Agricultural Machinery, 2013, 44(01): 73-79+89.

[0008] [3] Chen Jianglin, Lü Hongxing, Shi Xi, et al. Numerical simulation and experimental study on hydraulic characteristics of T-shaped three-way pipes [J]. Transactions of the Chinese Society of Agricultural Engineering, 2012, 28(05): 73-77.

[0009] [4] Shi Xi, Lü Hongxing, Zhu Delan, et al. Experiment and numerical simulation on hydraulic transient conditions of dendritic pipe networks [J]. Journal of Drainage and Irrigation Machinery Engineering, 2013, 31(05): 406-412.

[0010] [5] L, L, I, et al. Experimental and numerical investigation of mixing phenomena in double-tee junctions [J]. Water, 2019, 11(6): 1198.

[0011] [6] Ma L, He L, Luo X, et al. Experimental investigation of gas-liquid two-phase splitting in parallel pipelines with risers [J]. Chemical Engineering Research and Design, 2020, 161: 75-89.

[0012] [7] Su Heng, Qu Yegao, Zhou Shaochong, et al. Experimental study on flow-induced vibration of two-phase flow in horizontal T-shaped pipes [J]. Acta Aerodynamica Sinica, 2021, 39(03): 130-137.

[0013] [8] Liu Shengchun, Song Ming, Dai Baomin, et al. Simulation and experimental study on pressure drop characteristics of ice slurry flow in pipes [J]. Journal of Refrigeration, 2018, 39(02): 61-67.

[0014] [9]Kumano H,Kobayashi T,Morimoto T,et al.Experimental study on flowcharacteristics of ice slurry through a T-junction Part I:Laminar flow[J].International Journal of Refrigeration,2020,116:89-95.

[0015]

[10] Duan G,Liu Z,Chen G,et al.Experimental investigation of gas-solidtwo-phase flow in Y-shaped pipeline[J].Advanced Powder Technology,2010,21:468-476.

[0016] Currently, there is no simulation method for three-phase mixtures composed of water, fine particles, and coarse particles, that is, the coarse particles in sediment-laden water flow. In addition, existing research mainly focuses on bifurcated pipelines arranged vertically or horizontally as a whole, and there is little research on bifurcated pipelines with an overall inclined reverse slope, while the pipeline system layout in engineering practice inevitably has an overall inclined section. However, there is currently no simple, practical, and convenient simulation method for studying the transportation characteristics of coarse particles in sediment-laden water flow in bifurcated pipelines. Summary of the Invention:

[0017] The present invention is made to solve the above problems, and its purpose is to provide a method for simulating the transportation characteristics of coarse particles in sediment-laden water flow in bifurcated pipelines, which can study the transportation process of bifurcated pipelines with different inclination angles, achieve rapid setting of different research working conditions, and is simple to operate, practical, and convenient.

[0018] The technical solution of the present invention is as follows:

[0019] A method for simulating the transportation characteristics of coarse particles in sediment-laden water flow in bifurcated pipelines, characterized by comprising the following steps:

[0020] Step 1: Install a hydraulic model for studying the transportation characteristics of coarse particles in sediment-laden water flow in bifurcated pipelines.

[0021] The hydraulic model includes a forward and backward water pool system, a test pipeline system, and a water diversion pipeline system. The forward and backward water pool system includes a first pool, a second pool, and a third pool. The test pipeline system includes a first test pipeline, a second test pipeline, and a third test pipeline. The water diversion pipeline system includes three forward and backward water pool transfer pipelines. The first pool, the second pool, and the third pool are pairwise connected through the three forward and backward water pool transfer pipelines to form a triangular layout. One end of the first test pipeline, the second test pipeline, and the third test pipeline is respectively connected to the first pool, the second pool, and the third pool. The other ends of the first test pipeline, the second test pipeline, and the third test pipeline converge and connect at a point to form a tee pipeline;

[0022] The first pool is an intake pool, and the second pool and the third pool are drainage pools; a sand pumping pump is provided in the first pool. The sand pumping pump is fixed on the steel bracket of the sand pumping pump and is connected to the first test pipeline for pumping the sediment-laden water flow into the first test pipeline; on the inner walls of the pool bodies of the second pool and the third pool, a coarse particle underwater filter screen and a coarse particle underwater weighing sensor are fixedly arranged. The coarse particle underwater weighing sensor is fixed on the steel bracket of the coarse particle underwater weighing sensor and is connected to the data acquisition instrument of the coarse particle underwater weighing sensor;; sediment-laden water flow stirrers are provided in the pool bodies of the first pool, the second pool, and the third pool;

[0023] The first test pipeline, the second test pipeline, and the third test pipeline are all made of transparent plexiglass; the first test pipeline, the second test pipeline, and the third test pipeline all include a control section and an observation section. Among them, the control section is the end of the first test pipeline, the second test pipeline, and the third test pipeline close to the first pool, the second pool, and the third pool, and the observation section is the end of the first test pipeline, the second test pipeline, and the third test pipeline far from the first pool, the second pool, and the third pool; the observation section is connected to the control section through a flange with a set inclination angle;

[0024] On the control sections of the first test pipeline, the second test pipeline, and the third test pipeline, there are test pipeline control valves, electromagnetic flowmeters, and coarse particle feeding pipelines. The upper end of the coarse particle feeding pipeline is provided with a coarse particle feeding port, and the lower end is provided with a coarse particle control valve for controlling the opening and closing of the coarse particle feeding pipeline;

[0025] The lowest height H of the coarse particle feeding port is determined by formula (1):

[0026]

[0027] In the formula, h t is the head of the sand pumping pump, Z1 is the height of the water surface of the first pool from the bottom horizontal plane of the control section of the first test pipeline, α is the velocity head correction coefficient, vmax $v_{max}$ is the maximum flow velocity during the test process, $g$ is the acceleration due to gravity, $\lambda$ is the coefficient of head loss along the path, $L$ is the distance of the water flow from the sand pump along the pipeline to the first coarse particle feeding pipeline, $d$ is the inner diameter of the test pipeline, $\zeta_1$ is the local head loss coefficient at the sand pump, $\zeta_2$ is the local head loss coefficient at the elbow section, $\zeta_3$ is the local head loss coefficient at the position of the electromagnetic flowmeter, $\zeta_4$ is the local head loss coefficient at the position of the control valve of the test pipeline, and $\zeta_5$ is the local head loss coefficient at the position of the coarse particle feeding pipeline;

[0028] The observation sections of the first test pipeline, the second test pipeline, and the third test pipeline are arranged in a closed rectangular glass water tank filled with clear water. A plurality of pressure detection holes are evenly distributed on the observation sections. Pressure sensors are arranged in the pressure detection holes. The outer part of the probe of the pressure sensor is wrapped with an anti-sediment filter screen. The pressure sensors are all connected to a pressure sensor signal acquisition instrument;

[0029] Step two, set the test conditions;

[0030] According to the set sediment concentration, add sediment to the water inlet pool, and turn on the sediment-laden water stirrer to stir and form sediment-laden water with the set sediment concentration; according to the set inclination angle, select a flange with the set inclination angle to connect the observation section and the control section, so as to form a set inclination angle between the observation section and the control section;

[0031] Step three, check whether there is sufficient water in the first pool. If there is not enough water, transfer the surplus water in the second pool and / or the third pool into the first pool by opening the control valve of the inlet and outlet pool transfer pipeline; set the parameters of the pressure sensor and the underwater weighing sensor for coarse particles, and zero the pressure;

[0032] Step four, set up the high-speed camera in front of the closed rectangular glass water tank to photograph the movement of coarse particles in clear water;

[0033] Step five, turn on the sand pump, and fully open the test pipeline control valves on the second test pipeline and the third test pipeline; adjust the opening of the test pipeline control valve on the first test pipeline: first, make a rough adjustment. When observing that the flow rate value displayed by the electromagnetic flowmeter reaches near the target flow rate, then make a fine adjustment until it is adjusted to the target flow rate and the flow rate value no longer fluctuates, and the adjustment is completed;

[0034] Step 6: Turn on the data collector for the underwater coarse particle weighing sensor and the signal collector for the pressure sensor; open the coarse particle control valve on the first test pipeline, close the coarse particle control valves on the second and third test pipelines, evenly pour the coarse particles into the coarse particle feeding port on the first test pipeline, turn on the high-speed camera, and at the same time time with a stopwatch. Record the time once when the coarse particles just enter the first test pipeline, and record the time once when they completely leave the second and third test pipelines.

[0035] Step 7: Wait until the coarse particles completely flow out of the second and third test pipelines, then turn off the high-speed camera, the data collector for the underwater coarse particle weighing sensor, the signal collector for the pressure sensor, and the sand pump. After the clear water in the three test pipelines completely flows out, close the control valves of the three test pipelines.

[0036] Step 8: Export the test data, and fish out and recycle the coarse particles filtered out by the underwater coarse particle filter screen.

[0037] Step 9: Process the exported test data.

[0038] Preferably, the inclination angle range of the flange is between 0° and 90°.

[0039] Preferably, the lower parts of the first test pipeline, the second test pipeline and the third test pipeline are provided with movable and telescopic supports, and the movable and telescopic supports include telescopic rods, pipe clamps, fixed pins, universal wheels and universal wheel brakes.

[0040] The inventive points of the present invention compared with the prior art are reflected in the following aspects:

[0041] The present invention first proposes a simulation method for studying the transportation characteristics of coarse particles in sediment-laden flow in a bifurcated pipeline. Through the sediment-laden flow agitator in the inlet and outlet pools, sediment-laden flows with different sediment concentrations can be quickly stirred by mixing water and sediment in different proportions. By removing the flange and using a movable and telescopic support, one end of the device can be conveniently lifted and fixed to form a pipeline with an overall inclination angle. By taking advantage of the detachability of the sand pump in the inlet and outlet pools and the underwater weighing sensor for coarse particles, the inlet pool and the outlet pool can be conveniently switched back and forth to meet the test conditions of different inlet and outlet flow forms in the test. By using a sediment-proof filter screen, the fluid pressure in the pipeline can be accurately measured, while preventing the pressure sensor from being damaged by frequent impacts of sediment particles. An airtight rectangular glass water tank is adopted to reduce the distortion of the captured images caused by the different refractive indices of organic glass, water flow, etc., and improve the observation accuracy of the high-speed camera. Between the three groups of inlet and outlet pools, water can be transferred back and forth by using transfer pipelines and transfer valves, realizing the recycling of water flow, and playing a role in saving water resources. The simulation method proposed in this invention patent is easy to operate, the measured test data is complete and accurate, the test conditions that can be studied are comprehensive, and a large amount of manpower and material resources can be saved. BRIEF DESCRIPTION OF THE DRAWINGS:

[0042] Figure 1 is the side view of the hydraulic model adopted by the present invention;

[0043] Figure 2 is the top view of the hydraulic model adopted by the present invention;

[0044] Figure 3 is the top view of the inlet pool of the present invention;

[0045] Figure 4 is the A-A cross-sectional view of the inlet pool of the present invention;

[0046] Figure 5 is the top view of the outlet pool of the present invention;

[0047] Figure 6 is the B-B cross-sectional view of the outlet pool of the present invention;

[0048] Figure 7 is the front view of the movable and telescopic support of the present invention;

[0049] Figure 8 is the side view of the movable and telescopic support of the present invention;

[0050] Figure 9 is the side view of the test pipeline in the C-C section of the present invention;

[0051] Figure 10 is the top view of the test pipeline in the C-C section of the present invention;

[0052] Figure 11 It is a side view when the bifurcation angle of the test pipeline of the hydraulic model of the present invention changes;

[0053] Figure 12 It is a top view when the bifurcation angle of the test pipeline of the hydraulic model of the present invention changes;

[0054] Figure 13 It is a side view when the overall inclination angle of the hydraulic model of the present invention is 30°;

[0055] Figure 14 It is a top view when the overall inclination angle of the hydraulic model of the present invention is 30°;

[0056] Figure 15 It is a side view when the overall inclination angle of the hydraulic model of the present invention is 60°;

[0057] Figure 16 It is a top view when the overall inclination angle of the hydraulic model of the present invention is 60°;

[0058] Figure 17 It is a schematic diagram after the test data of the present invention is processed.

[0059] Among them, 1 is the first pool, 2 is the second pool, 3 is the third pool, 4 is the test pipeline control valve, 5 is the electromagnetic flowmeter, 6 is the coarse particle feeding port, 7 is the coarse particle feeding pipeline, 8 is the coarse particle control valve, 9 is the movable and telescopic support, 10 is the flange, 11 is the water flow direction in the pipeline, 12 is the pressure sensor, 13 is the sealed rectangular glass water tank, 14 is the first test pipeline, 15 is the second test pipeline, 16 is the third test pipeline, 17 is the high-speed camera, 18 is the data acquisition instrument for the underwater weighing sensor of coarse particles, 19 is the pipeline for calling the inlet and outlet pools, 20 is the control valve for the pipeline for calling the inlet and outlet pools, 21 is the signal acquisition instrument for the pressure sensor, 22 is the sand pump, 23 is the steel support for the sand pump, 24 is the pool body, 25 is the sediment-laden water stirrer, 26 is the underwater filter for coarse particles, 27 is the underwater weighing sensor for coarse particles, 28 is the steel support for the underwater weighing sensor for coarse particles, 29 is the telescopic rod, 30 is the pipe clamp, 31 is the fixed pin, 32 is the universal wheel, 33 is the universal wheel brake, and 34 is the anti-silt filter screen. Specific implementation manner:

[0060] In combination with the accompanying drawings, the present invention will be described in detail.

[0061] A method for simulating the transportation characteristics of coarse particles in sediment-laden flow in a bifurcated pipeline. The hydraulic model used includes an inlet and outlet pool system, a test pipeline system, and a water diversion pipeline system. The inlet and outlet pool system includes a first pool 1, a second pool 2, and a third pool 3. The test pipeline system includes a first test pipeline 14, a second test pipeline 15, and a third test pipeline 16. The water diversion pipeline system includes three inlet and outlet pool transfer pipelines 19. The first pool 1, the second pool 2, and the third pool 3 are pairwise connected through the three inlet and outlet pool transfer pipelines 19 to form a triangular layout. One end of the first test pipeline 14, the second test pipeline 15, and the third test pipeline 16 is respectively connected to the first pool 1, the second pool 2, and the third pool 3, and the other ends of the first test pipeline 14, the second test pipeline 15, and the third test pipeline 16 converge and connect at a point to form a tee pipeline.

[0062] In this embodiment, the first pool 1 is an inlet pool, and the second pool 2 and the third pool 3 are outlet pools. A sand pump 22 and a sand pump steel support 23 are provided in the first pool 1. The sand pump steel support 23 is fixed on the inner wall of the pool body 24, and the sand pump 22 is fixed on the sand pump steel support 23 and connected to the first test pipeline 14 for pumping the sediment-laden flow into the first test pipeline 14. Coarse particle underwater filters 26 and coarse particle underwater weighing sensor steel supports 28 are fixedly arranged on the inner walls of the pool bodies 24 of the second pool 2 and the third pool 3. Coarse particle underwater weighing sensors 27 are fixed on the coarse particle underwater weighing sensor steel supports 28 and connected to a coarse particle underwater weighing sensor data acquisition instrument 18. Sediment-laden flow stirrers 25 are provided in the pool bodies 24 of the first pool 1, the second pool 2, and the third pool 3 for stirring the mixture of sediment and water in the pool bodies 24. When the coarse particles flow out with the sediment-laden flow and fall on the coarse particle underwater weighing sensors 27, the coarse particle underwater weighing sensor data acquisition instrument 18 can record the weight information of the coarse particles. The coarse particle underwater filters 26 are used to filter the coarse particles in the sediment-laden flow for convenient recycling.

[0063] The sand pump 22, the sand pump steel support 23 in the first pool 1, and the coarse particle underwater weighing sensor data acquisition instrument 18, the coarse particle underwater filter 26, the coarse particle underwater weighing sensor 27, and the coarse particle underwater weighing sensor steel support 28 in the second pool 2 and the third pool 3 are all detachable devices, enabling the first pool 1, the second pool 2, and the third pool 3 to be quickly and conveniently converted into an inlet pool or an outlet pool.

[0064] The first test pipeline 14, the second test pipeline 15, and the third test pipeline 16 are made of transparent plexiglass material to facilitate observing the movement state of coarse particles in the pipeline.

[0065] The first test pipeline 14, the second test pipeline 15, and the third test pipeline 16 include a control section and an observation section. The control section is the end of the first test pipeline 14, the second test pipeline 15, and the third test pipeline 16 close to the first water tank 1, the second water tank 2, and the third water tank 3, and the observation section is the end of the first test pipeline 14, the second test pipeline 15, and the third test pipeline 16 far from the first water tank 1, the second water tank 2, and the third water tank 3. The observation section is connected to the control section through a flange 10 with different inclination angles. According to the test requirements, different inclination angles are formed between the observation section and the control section, and the flange 10 with various inclination angles between 0° and 90° can be used.

[0066] Test pipeline control valves 4, electromagnetic flowmeters 5, and coarse particle feeding pipelines 7 are provided on the control sections of the first test pipeline 14, the second test pipeline 15, and the third test pipeline 16. A coarse particle feeding port 6 is provided at the upper end of the coarse particle feeding pipeline 7, and a coarse particle control valve 8 is provided at the lower end to control the opening and closing of the coarse particle feeding pipeline 7.

[0067] The coarse particle feeding pipeline 7 is a channel for coarse particles to enter the test pipeline and is thus connected to the test pipeline. During the test, the coarse particle control valve 8 is fully opened. When the water flow is sucked out by the sand pump 22 and flows through the coarse particle feeding pipeline 7, since the flowing water in the test pipeline is a pressurized flow, a water column of a certain height will appear in the coarse particle feeding pipeline 7. Therefore, the minimum height of the coarse particle feeding port 6 must be determined to prevent the water flow in the test pipeline from overflowing from the coarse particle feeding port 6 of the coarse particle feeding pipeline 7. The height of the coarse particle feeding port 6 described in the present invention refers to the relative height between the top end of the coarse particle feeding port 6 and the cross-sectional area of the test pipeline through which the fluid flows.

[0068] The present invention determines the minimum height H of the coarse particle feeding port 6 that meets the test requirements by the following formula:

[0069]

[0070] In the formula, h t is the head of the sand pump 22, Z1 is the height of the water surface of the first water tank 1 from the bottom horizontal plane of the control section of the first test pipeline 14, α is the velocity head correction coefficient, v max is the maximum flow velocity that appears during the test, g is the acceleration due to gravity, λ is the coefficient of head loss along the path, L is the distance of the water flow from the sand pump 22 along the pipeline to the first coarse particle feeding pipeline, d is the inner diameter of the test pipeline, ζ1 is the local head loss coefficient at the sand pump 22, ζ2 is the local head loss coefficient at the elbow section, ζ3 is the local head loss coefficient at the position of the electromagnetic flowmeter 5, ζ4 is the local head loss coefficient at the position of the test pipeline control valve 4, and ζ5 is the local head loss coefficient at the position of the coarse particle feeding pipeline 7. Among them, ht 、Z1, v max 、L and d are obtained according to the design and actual measurement, and other parameters are obtained through experiments.

[0071] In this embodiment, according to the device size of the preliminary design, the parameters of the test equipment, and the test flow rate, it can be known that λ = 0.03, ζ1 = 0.25, ζ2 = 0.30, ζ3 = 0.50, ζ4 = 0.20, ζ5 = 0.20, α = 1.0, L = 4.0 m, d = 0.1 m, v max = 2.5 m / s, Z1 = 1.5 m, g = 9.81 m / s 2 , h t = 5.0 m, and H = 2.34 m can be obtained, that is, the lowest height H of the coarse particle feeding port 6 is 2.34 m. Otherwise, water will gush out from the coarse particle feeding port 6 during the test, resulting in the failure of the test. However, if the height of the coarse particle feeding port 6 is designed too high, it will lead to a large occupied space and difficult feeding. Therefore, in actual operation, after determining the accurate value of the height of the coarse particle feeding port 6 using the above formula, the height of the coarse particle feeding port 6 is actually determined to be 2.50 m.

[0072] The observation sections of the first test pipeline 14, the second test pipeline 15, and the third test pipeline 16 are arranged in the closed rectangular glass water tank 13 filled with clear water, which is used to reduce the distortion of the camera pictures caused by the refractive indices of different substances such as plexiglass and water flow, and improve the observation accuracy of the high-speed camera. The high-speed camera 17 is used to photograph the movement of coarse particles in the water flow.

[0073] A plurality of pressure detection holes are evenly distributed on the observation sections of the first test pipeline 14, the second test pipeline 15, and the third test pipeline 16. A pressure sensor 12 is arranged in the pressure detection hole, and the side head of the pressure sensor 12 is wrapped with an anti-silt filter screen 34 to prevent the silt in the water flow from entering the pressure sensor 12, improve the measurement accuracy, and reduce the probability of damage to the pressure sensor 12. During the test, all the pressure sensors 12 are connected to the pressure sensor signal acquisition instrument 21.

[0074] A control valve 20 for the advance and retreat water tank calling pipeline is provided on the advance and retreat water tank calling pipeline 19. By opening and closing the three groups of control valves 20 for the advance and retreat water tank calling pipeline, the water in the first water tank 1, the second water tank 2, and the third water tank 3 can be called back and forth.

[0075] The lower parts of the first test pipeline 14, the second test pipeline 15, and the third test pipeline 16 are provided with a movable and telescopic support 9. The movable and telescopic support 9 includes a telescopic rod 29, a pipe clamp 30, a fixed pin 31, a universal wheel 32, and a universal wheel brake 33. The telescopic rod 29 is used to lift the height of the pipe clamp 30. Each section of it has multiple holes. Passing the fixed pin 31 through the holes can fix its height. The pipe clamp 30 adopts an openable and closable design. By opening the pipe clamp 30, the three groups of test pipelines can be conveniently installed and clamped. The design of the universal wheel 32 enables the entire support to move flexibly. The universal wheel brake 33 is used to brake the universal wheel so that the entire support will not be displaced after being placed in a fixed position.

[0076] In the test process of the present invention, the coarse particle sizes used are 2mm, 4mm, 6mm, 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm respectively, and the test flow velocities are 1.0m / s, 1.5m / s, 2.0m / s, 2.5m / s respectively. The following further details a method for simulating the coarse particle transportation characteristics of sediment-laden water flow in a bifurcated pipeline of the present invention through different embodiments.

[0077] Embodiment 1:

[0078] The test conditions are set as follows: the sediment concentration of the sediment-laden water flow is 0, that is, clear water. The included angle between the first test pipeline 14, the second test pipeline 15, and the third test pipeline 16 is 120°. The inclination angle of the first test pipeline 14 is 0°. The pipeline inlet and outlet flow form is one inlet and two outlets, that is: the first test pipeline 14 is the inlet pipeline, and the second test pipeline 15 and the third test pipeline 16 are the outlet pipelines. The specific test steps are as follows:

[0079] Step A1, install and debug the hydraulic model for studying the coarse particle transportation characteristics of sediment-laden water flow in a bifurcated pipeline of the present invention;

[0080] Step A2, check whether there is sufficient water in the first pool 1. If not, then transfer the surplus water in the second pool 2 and / or the third pool 3 into the first pool 1 by opening the control valve of the inlet and outlet pool connection pipeline 20.

[0081] Step A3, connect the pressure sensor 12 and the underwater weighing sensor for coarse particles 27 to the pressure sensor signal acquisition instrument 21 and the underwater weighing sensor data acquisition instrument for coarse particles 18 respectively, set the parameters of the pressure sensor 12 and the underwater weighing sensor for coarse particles 27, and zero the pressure.

[0082] Step A4, set up the high-speed camera 17 in front of the sealed rectangular glass water tank 13 to photograph the movement of coarse particles in clear water.

[0083] Step A5: Turn on the sand pump 22, fully open the test pipeline control valves 4 on the second test pipeline 15 and the third test pipeline 16; adjust the opening degree of the test pipeline control valve 4 on the first test pipeline 14: First, make a rough adjustment. When observing that the flow rate value displayed by the electromagnetic flowmeter 5 reaches near the target flow rate, then make a fine adjustment until the target flow rate is adjusted and the flow rate value no longer fluctuates. The adjustment is completed.

[0084] Step A6: Turn on the data acquisition instrument 18 for the underwater coarse particle weighing sensor and the signal acquisition instrument 21 for the pressure sensor. Open the coarse particle control valve 8 on the first test pipeline 14, close the coarse particle control valves 8 on the second test pipeline 15 and the third test pipeline 16, evenly pour a certain amount of coarse particles into the coarse particle feeding port 6 on the first test pipeline 14, turn on the high-speed camera 17, and at the same time time with a stopwatch. Record the time once when the coarse particles just enter the first test pipeline 14, and record the time once when they completely leave the second test pipeline 15 and the third test pipeline 16.

[0085] Step A7: Wait until the coarse particles completely flow out of the second test pipeline 15 and the third test pipeline 16, then turn off the high-speed camera 17, the data acquisition instrument 18 for the underwater coarse particle weighing sensor, the signal acquisition instrument 21 for the pressure sensor, and the sand pump 22. After the clear water in the three test pipelines completely flows out, close the three test pipeline control valves 4.

[0086] Step A8: Export the test data, and fish out and recycle the coarse particles filtered out by the underwater coarse particle filter screen 26.

[0087] Step A9: Process the exported test data:

[0088] During the test process, the measured instantaneous pressure p collected by the pressure sensor consists of the time-averaged pressure and the pulsating pressure p'. The average value of the measured instantaneous pressure p is the time-averaged pressure Subtracting the time-averaged pressure from the measured instantaneous pressure p can obtain the pulsating pressure p'. Its expression is:

[0089]

[0090] Divide the measured pulsating pressure p′ into several sub-intervals according to its magnitude, calculate the occurrence times of the pulsating pressure in each sub-interval and its proportion in the whole, and fit it with the Gaussian distribution function to obtain the following fitting formula:

[0091]

[0092] In the formula: f(p) is the probability density function; μ is the expectation of the fluctuating pressure; σ is the variance of the fluctuating pressure. μ is the position parameter of the probability density fitting function, which determines the position of the distribution function. σ is the shape parameter of the probability density fitting function, which determines the degree of dispersion of the distribution function. The larger σ is, the more dispersed the data distribution is; the smaller σ is, the more concentrated the data distribution is.

[0093] To process the motion fluctuating pressure signal of coarse particles in pipeline fluid, the fast Fourier transform method is adopted. By converting the time-domain signal of the fluctuating pressure into a frequency-domain signal, the amplitude spectral density function, phase spectral density function, and power spectral density function of the fluctuating pressure are obtained. This series of functions together constitute the spectral density distribution of the fluctuating pressure in the coarse particle pipeline. The expression of the Fourier transform of the non-periodic continuous-time signal f(t) is:

[0094]

[0095] Figure 17 A is the distribution diagram of the fluctuating pressure generated when coarse particles with a particle size of 12 mm enter the test pipeline with a test flow rate of 1 m / s at a sediment transport rate of 0.208 kg / s; Figure 17 B is the time-averaged pressure distribution diagram at different detection points when coarse particles with a particle size of 12 mm enter the test pipeline with a test flow rate of 1 m / s at a sediment transport rate of 0.208 kg / s; Figure 17 C is the frequency histogram generated when coarse particles with a particle size of 12 mm enter the test pipeline with a test flow rate of 1 m / s at a sediment transport rate of 0.208 kg / s; Figure 17 D is the power spectrum diagram generated when coarse particles with a particle size of 12 mm enter the test pipeline with a test flow rate of 1 m / s at a sediment transport rate of 0.208 kg / s.

[0096] Example 2:

[0097] The test conditions are set as follows: the sediment concentration of the sediment-laden water is 50 kg / m 3 ,, the included angle between the first test pipeline 14, the second test pipeline 15, and the third test pipeline 16 is 120°, the inclination angle of the first test pipeline 14 is 0°, and the pipeline inlet and outlet flow form is one inlet and two outlets, that is: the first test pipeline 14 is the water inlet pipeline, and the second test pipeline 15 and the third test pipeline 16 are the water outlet pipelines. The specific test steps are as follows:

[0098] Step B1 is the same as step A1.

[0099] Step B2 is the same as step A2.

[0100] Step B3, the sediment concentration calculation formula is:

[0101]

[0102] In the formula, S refers to the sediment concentration of the sediment-laden flow, m refers to the total mass of added sediment, ρ s refers to the sediment density used in the experiment, and V refers to the volume of water.

[0103] The sediment density used in the experiment is 2650 kg / m 3 , and the preset water volume in the first pool 1 is 2 m 3 . According to the above formula, it can be known that 101.92 kg of sand is added to the first pool 1, and the sediment-laden flow stirrer 25 is turned on to stir to form a sediment-laden flow with a sediment concentration of 50 kg / m 3 .

[0104] Step B4 is the same as step A3.

[0105] In step B5, since the sediment-laden flow is turbid and the high-speed camera 17 cannot capture the movement of coarse particles, it is removed.

[0106] Step B6 is the same as step A5.

[0107] In step B7, turn on the data acquisition instrument 18 for the underwater weighing sensor of coarse particles and the signal acquisition instrument 21 for the pressure sensor. Open the coarse particle control valve 8 on the first test pipeline 14, close the coarse particle control valves 8 on the second test pipeline 15 and the third test pipeline 16, evenly pour a certain amount of coarse particles into the coarse particle feeding port 6 on the first test pipeline 14, and at the same time time with a stopwatch. Record the time once when the coarse particles just enter the first test pipeline 14, and record the time once when they completely leave the second test pipeline 15 and the third test pipeline 16.

[0108] In step B8, when the coarse particles completely flow out of the second test pipeline 15 and the third test pipeline 16, turn off the data acquisition instrument 18 for the underwater weighing sensor of coarse particles, the signal acquisition instrument 21 for the pressure sensor, and the sand pump 22. After the sediment-laden flow in the test pipeline completely flows out, close the control valves of the three test pipelines.

[0109] Step B9 is the same as step A8.

[0110] Step B10 is the same as step A9.

[0111] Example 3:

[0112] The test conditions are set as follows: the sediment concentration of the sediment-laden flow is 50 kg / m 3, the included angles between the first test pipeline 14, the second test pipeline 15 and the third test pipeline 16 are 180°, the inclination angle of the first test pipeline 14 is 0°, and the pipeline inlet and outlet flow form is one inlet and two outlets, that is: the first test pipeline 14 is the water inlet pipeline, and the second test pipeline 15 and the third test pipeline 16 are the water outlet pipelines. The specific test steps are as follows:

[0113] Step C1, remove the second test pipeline 15 and the third test pipeline 16 with the original included angle not being 180°, then move the movable and telescopic bracket 9 to a suitable position, adjust the direction of the pipe clamp 30, open the pipe clamp 30, fix the second test pipeline 15 and the third test pipeline 16 with an included angle of 180° using the pipe clamp 30, and install and fix the connection position with the flange 10. The test pipeline with a 180° included angle of the bifurcated pipeline is assembled.

[0114] Step C2 is the same as step A1.

[0115] Step C3 is the same as step A2.

[0116] Step C4 is the same as step B3.

[0117] Step C5 is the same as step A3.

[0118] Step C6 is the same as step B5.

[0119] Step C7 is the same as step A5.

[0120] Step C8 is the same as step B7.

[0121] Step C9 is the same as step B8.

[0122] Step C10 is the same as step A8.

[0123] Step C11 is the same as step A9.

[0124] Example 4:

[0125] The test working condition is set as: the sediment concentration of the sediment-laden water flow is 50 kg / m 3 , the included angles between the first test pipeline 14, the second test pipeline 15 and the third test pipeline 16 are 180°, the inclination angle of the first test pipeline 14 is 30°, and the pipeline inlet and outlet flow form is one inlet and two outlets, that is: the first test pipeline 14 is the water inlet pipeline, and the second test pipeline 15 and the third test pipeline 16 are the water outlet pipelines. The specific test steps are as follows:

[0126] Step D1: Disassemble the pipe fittings. Use the telescopic rod 29 to raise and lower the height of the pipe clamp 30. After reaching the target height, insert the fixing pin 31 through the hole to fix it. Adjust the direction of the pipe clamp 30, open the pipe clamp 30, fix the target test pipe with the pipe clamp 30, and install and fix the connection position with the flange 10. The test device with an overall inclination angle of 30° is assembled.

[0127] Step D2: The same as step A1.

[0128] Step D3: The same as step A2.

[0129] Step D4: The same as step B3.

[0130] Step D5: The same as step A3.

[0131] Step D6: The same as step B5.

[0132] Step D7: The same as step A5.

[0133] Step D8: The same as step B7.

[0134] Step D9: The same as step B8.

[0135] Step D10: The same as step A8.

[0136] Step D11: The same as step A9.

[0137] Example 5:

[0138] The test working condition is set as follows: the sediment concentration of the sediment-laden water flow is 50 kg / m 3 , the included angle between the first test pipe 14, the second test pipe 15 and the third test pipe 16 is 180°, the inclination angle of the first test pipe 14 is 60°, and the pipe inlet and outlet form is two inlets and one outlet, that is: the first test pipe 14 and the second test pipe 15 are the inlet pipes, and the third test pipe 16 is the outlet pipe. The specific test steps are as follows:

[0139] Step E1: Disassemble the pipe fittings. Use the telescopic rod 29 to raise and lower the height of the pipe clamp 30. After reaching the target height, insert the fixing pin 31 through the hole to fix it. Adjust the direction of the pipe clamp 30, open the pipe clamp 30, fix the target test pipe with the pipe clamp 30, and install and fix the connection position with the flange 10. The test device with an overall inclination angle of 60° is assembled.

[0140] Step E2: Set the first water tank 1 and the second water tank 2 as the inlet water tanks.

[0141] Step E3: Check whether there is sufficient and quantitative water in the first pool 1 and the second pool 2. If the water volume is insufficient or excessive, use the three groups of inlet and outlet pool call pipes 19 to call the water in the three-pool system until the water volume in the first pool 1 and the second pool 2 reaches the test requirements.

[0142] Step E4: Add a quantitative amount of sand to the first pool 1 and the second pool 2, and turn on the sand-containing water flow stirrer 25 to stir and form a sand-containing water flow with a sand content of 50 kg / m3.

[0143] Step E5: The same as step A3.

[0144] Step E6: The same as step B5.

[0145] Step E7: Turn on the sand pump 22, fully open the test pipe control valve 4 on the third test pipe 16, and adjust the opening degrees of the test pipe control valves 4 on the first test pipe 14 and the second test pipe 15. First, perform a rough adjustment. When it is observed that the flow rate values displayed by the electromagnetic flow meters 5 on the first test pipe and the second test pipe reach near the target flow rate, then perform a fine adjustment until the target flow rate is adjusted and the flow rate value no longer fluctuates, and the adjustment is completed.

[0146] Step E8: Turn on the data acquisition instrument 18 for the underwater weighing sensor of coarse particles and the signal acquisition instrument 21 for the pressure sensor. Open the coarse particle control valves 8 on the first test pipe 14 and the second test pipe 15, close the coarse particle control valve 8 on the third test pipe 16, and evenly pour a quantitative amount of coarse particles into the coarse particle feeding ports 6 on the first test pipe 14 and the second test pipe 15. At the same time, use a stopwatch to time. Record the time once when the coarse particles just enter the first test pipe 14 and the second test pipe 15, and record the time once when they completely leave the third test pipe 16.

[0147] Step E9: When the coarse particles completely flow out of the third test pipe 16, turn off the data acquisition instrument 18 for the underwater weighing sensor of coarse particles, the signal acquisition instrument 21 for the pressure sensor, and the sand pump 22. After the sand-containing water flow in the test pipe completely flows out, close the three test pipe control valves.

[0148] Step E10: The same as step A8.

[0149] Step E11: The same as step A9.

Claims

1. A method for simulating the coarse particle transport characteristics of sediment-laden flow in a bifurcated pipeline, characterized in that, It includes the following steps: Step 1: Install a hydraulic model for studying the coarse particle transportation characteristics of sediment-laden flow in a bifurcated pipeline; The hydraulic model includes an inlet and outlet pool system, a test pipeline system, and a water diversion pipeline system. The inlet and outlet pool system includes a first pool (1), a second pool (2), and a third pool (3). The test pipeline system includes a first test pipeline (14), a second test pipeline (15), and a third test pipeline (16). The water diversion pipeline system includes three inlet and outlet pool transfer pipelines (19). The first pool (1), the second pool (2), and the third pool (3) are pairwise connected by the three inlet and outlet pool transfer pipelines (19) to form a triangular layout. One end of the first test pipeline (14), the second test pipeline (15), and the third test pipeline (16) is respectively connected to the first pool (1), the second pool (2), and the third pool (3). The other ends of the first test pipeline (14), the second test pipeline (15), and the third test pipeline (16) converge and connect at a point to form a tee pipeline; The first pool (1) is an inlet pool, and the second pool (2) and the third pool (3) are outlet pools; a sand pumping pump (22) is provided in the first pool (1). The sand pumping pump (22) is fixed on a sand pumping pump steel bracket (23) and is connected to the first test pipeline (14) for pumping sediment-laden flow into the first test pipeline (14); a coarse particle underwater filter screen (26) and a coarse particle underwater weighing sensor (27) are fixedly arranged on the inner wall of the pool body (24) of the second pool (2) and the third pool (3). The coarse particle underwater weighing sensor (27) is fixed on a coarse particle underwater weighing sensor steel bracket (28) and is connected to a coarse particle underwater weighing sensor data collector (18); a sediment-laden flow stirrer (25) is provided in the pool body (24) of the first pool (1), the second pool (2), and the third pool (3); The first test pipeline (14), the second test pipeline (15), and the third test pipeline (16) are all made of transparent plexiglass; the first test pipeline (14), the second test pipeline (15), and the third test pipeline (16) all include a control section and an observation section. The control section is the end of the first test pipeline (14), the second test pipeline (15), and the third test pipeline (16) close to the first pool (1), the second pool (2), and the third pool (3). The observation section is the end of the first test pipeline (14), the second test pipeline (15), and the third test pipeline (16) far from the first pool (1), the second pool (2), and the third pool (3); the observation section is connected to the control section through a flange (10) with a set inclination angle; On the control sections of the first test pipeline (14), the second test pipeline (15), and the third test pipeline (16), there are test pipeline control valves (4), electromagnetic flowmeters (5), and coarse particle feeding pipelines (7). At the upper end of the coarse particle feeding pipeline (7), there is a coarse particle feeding port (6), and at the lower end, there is a coarse particle control valve (8) for controlling the opening and closing of the coarse particle feeding pipeline (7); The lowest height H of the coarse particle feeding port (6) is determined by formula (1): where h t is the head of the sand pumping pump (22), Z1 is the height of the water surface of the first pool (1) from the bottom horizontal plane of the control section of the first test pipeline (14), α is the velocity head correction coefficient, v max is the maximum flow velocity that appears during the test, g is the acceleration due to gravity, λ is the coefficient of head loss along the way, L is the distance from the sand pumping pump (22) along the pipeline to the first coarse particle feeding pipeline, d is the inner diameter of the test pipeline, ζ1 is the coefficient of local head loss at the sand pumping pump (22), ζ2 is the coefficient of local head loss at the elbow section, ζ3 is the coefficient of local head loss at the position of the electromagnetic flowmeter (5), ζ4 is the coefficient of local head loss at the position of the control valve (4) of the test pipeline, and ζ5 is the coefficient of local head loss at the position of the coarse particle feeding pipeline (7); The observation sections of the first test pipeline (14), the second test pipeline (15), and the third test pipeline (16) are arranged in a closed rectangular glass water tank (13) filled with clear water. There are multiple pressure detection holes evenly distributed on the observation sections. Pressure sensors (12) are arranged in the pressure detection holes. The outer side of the heads of the pressure sensors (12) is wrapped with anti-sediment filter meshes (34). The pressure sensors (12) are all connected to a pressure sensor signal acquisition instrument (21); Step two, set the test conditions; According to the set sediment concentration, add sediment to the first water tank (1), and start the sediment-laden water stirrer (25) to stir and form sediment-laden water with the set sediment concentration; according to the set inclination angle, select a flange (10) with the set inclination angle to connect the observation section and the control section, so as to form a set inclination angle between the observation section and the control section; Step three, check whether there is sufficient water in the first water tank (1). If there is not enough water, open the control valve (20) of the inlet and outlet water tank transfer pipeline to transfer the surplus water in the second water tank (2) and / or the third water tank (3) into the first water tank (1); set the parameters of the pressure sensor (12) and the coarse particle underwater weighing sensor (27), and zero the pressure; Step four, set up the high-speed camera (17) in front of the closed rectangular glass water tank (13) to photograph the movement of coarse particles in clear water; Step five, start the sand pump (22), and fully open the test pipeline control valves (4) on the second test pipeline (15) and the third test pipeline (16); adjust the opening of the test pipeline control valve (4) on the first test pipeline (14): first, make a rough adjustment. When observing that the flow rate value displayed by the electromagnetic flowmeter (5) reaches near the target flow rate, then make a fine adjustment until the target flow rate is adjusted and the flow rate value no longer fluctuates, and the adjustment is completed; Step six, start the data acquisition instrument (18) of the coarse particle underwater weighing sensor and the pressure sensor signal acquisition instrument (21); open the coarse particle control valve (8) on the first test pipeline (14), close the coarse particle control valves (8) on the second test pipeline (15) and the third test pipeline (16), evenly pour the coarse particles into the coarse particle feeding port (6) on the first test pipeline (14), start the high-speed camera (17), and at the same time time with a stopwatch. Record the time once when the coarse particles just enter the first test pipeline (14), and record the time once when they completely leave the second test pipeline (15) and the third test pipeline (16); Step 7: When all the coarse particles have completely flowed out of the second test pipeline (15) and the third test pipeline (16), turn off the high-speed camera (17), the data acquisition instrument for the underwater weighing sensor of the coarse particles (18), the signal acquisition instrument for the pressure sensor (21), and the sand pump (22). After all the clear water in the three test pipelines has completely flowed out, close the control valves (4) of the three test pipelines. Step 8: Export the test data, and fish out and recycle the coarse particles filtered out by the underwater filter screen (26) for the coarse particles. Step 9: Process the exported test data.

2. A method for simulating the coarse particle transport characteristics of sediment-laden flow in a bifurcated pipeline, according to claim 1, characterized in that The inclination angle range of the flange (10) is between 0° and 90°.

3. A method for simulating the coarse particle transport characteristics of sediment-laden flow in a bifurcated pipeline, according to claim 1, wherein The lower parts of the first test pipeline (14), the second test pipeline (15), and the third test pipeline (16) are provided with a movable and telescopic support (9). The movable and telescopic support (9) includes a telescopic rod (29), a pipe clamp (30), a fixed bolt (31), a universal wheel (32), and a universal wheel brake (33).

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