Water hammer and leakage monitoring and positioning testing device and method for long-distance high-pressure water conveying pipeline

Abstract

The invention discloses a long-distance high-pressure water delivery pipeline water hammer and leakage monitoring and positioning test device, which comprises a water tank, a water outlet side experiment unit, a water return side main path experiment unit and a water return side branch experiment unit, and is characterized in that the water outlet side experiment unit and the water return side branch experiment unit are communicated with the water return side main path experiment unit; the water outlet side experiment unit, the water return side main path experiment unit and the water return side branch path experiment unit are all communicated with the water tank. The device solves the problem that tiny leakage is difficult to monitor in the high-pressure water delivery process in the existing related test experiment technology, and the problems that the water hammer experiment signal precision acquisition is insufficient and the water hammer experiment causes impact damage to equipment. The invention further discloses a using method of the long-distance high-pressure water conveying pipeline water hammer and leakage monitoring and positioning testing device.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-pressure water pipelines, and specifically relates to a water hammer, leakage monitoring and positioning test device for long-distance high-pressure water pipelines, and also relates to a method for using the water hammer, leakage monitoring and positioning test device for long-distance high-pressure water pipelines. Background Art

[0002] With the rapid development of urbanization in my country, long-distance water pipelines are increasingly being used in water supply projects (Design and Research of Automatic Monitoring System for Long-distance Water Pipeline [J]. Water Resources and Hydropower Technology (Chinese and English), 2024, 55(S1): 324-329). Long-distance water transmission mainly adopts high-pressure transmission. This is because high-pressure water transmission can overcome the limitations of terrain height difference and long distance, expand the scope of water supply, and has the advantages of low water pollution risk and conducive to ensuring water quality and quantity. However, there are still some problems that need to be solved in long-distance high-pressure pipeline water transmission. For example, due to factors such as complex geology along the line, even if the water pipeline meets the design quality standards during laying, it is inevitable that the pipeline will leak due to aging, fracture, corrosion, wear and other reasons (Research Progress and Frontier Scientific Issues of Hydraulic Control of Long-distance Water Transmission [J]. Journal of Hydraulic Engineering, 2016, 47(03): 424-435). In addition, since the multi-undulating water supply system accounts for a large proportion, and it has the characteristics of long pipelines and large terrain undulations, it is more prone to water hammer than straight pipelines. Sudden accidents such as water pump start-up and shutdown, improper valve operation, and sudden power outages will cause water hammer to varying degrees. Water hammer will not only damage the equipment in the water supply system, but may also cause the internal pressure of the pipeline to be too high and rupture, or it may be compressed due to the internal pressure dropping to steam pressure. (Research on the Height Reduction Scheme of the Pressure Stabilizing Tower in Long-Distance Multi-Branch Water Supply System [J]. Journal of Huazhong University of Science and Technology (Natural Science Edition), 2023, 51(08): 67-73). Therefore, for long-distance high-pressure pipeline water supply systems, it is urgent to take effective measures to improve the safety and stability of the pipeline and reduce the risks of leakage and water hammer.

[0003] Domestic and foreign researchers have conducted a large number of experimental and numerical simulation studies on leakage and water hammer problems, but they mainly focus on the exploration of media such as oil and gas, and rarely involve experimental research on long-distance high-pressure water transmission leakage detection and positioning technology and water hammer. In addition, the relevant experimental platforms generally only study leakage positioning experiments or water hammer experiments separately, and the functions are relatively single. However, the pressure fluctuations caused by the water hammer phenomenon exert additional stress on the pipeline, which makes it easy for pipeline leakage to occur, that is, there is an obvious coupling relationship between water hammer and leakage. Therefore, it is urgent to develop an experimental platform that can simultaneously explore the water hammer phenomenon and leakage positioning technology of long-distance pressurized water transmission pipelines. At the same time, there are several difficult factors in carrying out related test experiments that need to be solved urgently:

[0004] 1. To conduct long-distance high-pressure water pipeline leakage location and water hammer phenomenon exploration experiments, it is necessary to monitor and record the changes in pressure and flow data in real time. The instruments used include pressure sensors, displacement sensors, flow meters, data collectors, etc. If the equipment accuracy is low and the experimental data is inaccurate, the difficulty of the experiment will increase.

[0005] 2. Conducting leakage and water hammer experiments on long-distance high-pressure water pipelines requires strict control of the valve switching speed and valve opening (leakage aperture). Different switching speeds and valve openings will result in different data waveform changes.

[0006] 3. Conducting long-distance high-pressure water pipeline leakage and water hammer experiments involves high-pressure working conditions, which poses certain safety risks and may cause damage to equipment such as pipelines and water pumps. Therefore, in the early stages of the experimental platform design, it is necessary to consider installing a one-way valve and compensator to reduce the impact and damage of pressure fluctuations on related equipment such as water pumps. Summary of the invention

[0007] The purpose of the present invention is to provide a water hammer, leakage monitoring and positioning test device for long-distance high-pressure water transmission pipelines. The device solves the problems of difficulty in monitoring and locating tiny leaks occurring during high-pressure water transmission in existing testing experimental technologies, as well as the problems of insufficient accuracy in signal collection during water hammer experiments and impact damage to equipment caused by water hammer experiments.

[0008] Another object of the present invention is to provide a method for using a water hammer, leakage monitoring and positioning testing device for a long-distance high-pressure water pipeline.

[0009] The technical solution adopted by the present invention is a long-distance high-pressure water transmission pipeline water hammer, leakage monitoring and positioning test device, which includes a water tank, and also includes a water outlet side experimental unit, a return water side main line experimental unit and a return water side branch line experimental unit. The water outlet side experimental unit and the return water side branch line experimental unit are both connected to the return water side main line experimental unit, and the water outlet side experimental unit, the return water side main line experimental unit and the return water side branch line experimental unit are all connected to the water tank.

[0010] The present invention is also characterized in that:

[0011] The outlet side experimental unit includes a centrifugal pump, a ball valve, a first butterfly valve, a first electromagnetic flowmeter, a first displacement sensor, and a second displacement sensor which are sequentially connected through a pipeline. The second displacement sensor is connected to the return side main road experimental unit through a pipeline. The pipeline connecting the second displacement sensor and the return side main road experimental unit is sequentially provided with a fifth pressure sensor, a plurality of third leakage points, a sixth pressure sensor, a first automatic exhaust valve, and a second automatic exhaust valve according to the water flow direction.

[0012] A first pressure sensor and a second pressure sensor are provided on the pipeline between the first electromagnetic flowmeter and the first displacement sensor, and a plurality of first leakage points are provided on the pipeline between the first pressure sensor and the second pressure sensor;

[0013] A third pressure sensor, a plurality of second leakage points and a fourth pressure sensor are arranged on the pipeline between the first displacement sensor and the second displacement sensor according to the water flow direction.

[0014] The main line experimental unit on the return water side includes a third displacement sensor, a fourth displacement sensor, a second electromagnetic flowmeter, a manual exhaust valve, a second butterfly valve, an electric ball valve, a one-way valve and a first compensator which are connected in sequence through pipelines. The first compensator is connected to the water tank through a pipeline; the third displacement sensor is connected to the pipeline where the second automatic exhaust valve is located through a pipeline; the third automatic exhaust valve, the fourth automatic exhaust valve, the seventh pressure sensor, several fourth leakage points and the eighth pressure sensor are arranged in sequence on the pipeline between the second automatic exhaust valve and the third displacement sensor according to the direction of water flow; the ninth pressure sensor is arranged on the pipeline between the third displacement sensor and the fourth displacement sensor; the fifth leakage points, the tenth pressure sensor, the eleventh pressure sensor, several sixth leakage points and the twelfth pressure sensor are arranged in sequence on the pipeline between the fourth displacement sensor and the second electromagnetic flowmeter according to the direction of water flow; the pipeline between the manual exhaust valve and the second butterfly valve is connected to the return water side branch experimental unit.

[0015] The return side branch experimental unit connection includes a third butterfly valve, a back pressure valve and a second compensator which are connected in sequence through a pipeline according to the direction of water flow. The second compensator is connected to the water tank through a pipeline, and the second compensator is arranged close to the water tank.

[0016] Another technical solution adopted by the present invention is a method for using the above-mentioned long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device, which is specifically:

[0017] When doing leakage monitoring and positioning experiments, close the second butterfly valve and electric ball valve, open the third butterfly valve and back pressure valve, so that the return water returns to the water tank through the return branch experimental unit, and then open any leakage point to monitor the change of pipeline pressure value to achieve leakage monitoring and positioning;

[0018] When doing a water hammer test, close the third butterfly valve and back pressure valve, open the second butterfly valve and electric ball valve, allow the return water to return to the water tank through the return water main line test unit, then change the opening of the electric ball valve to monitor the changes in the pipeline pressure value to achieve a cut-off water hammer test; or close any leakage point to monitor the changes in the pipeline pressure value to achieve a valve-off water hammer test.

[0019] The present invention is also characterized in that:

[0020] The specific operation process for the leakage monitoring experiment is as follows: close the second butterfly valve and the electric ball valve to allow the return side water to return to the water tank through the return side branch experimental unit, manually change the pipeline pressure by increasing the pipeline pressure by 0.1MPa every ten seconds through the back pressure valve, change the power of the centrifugal pump to change the pipeline flow, observe the flow change through the first electromagnetic flowmeter and the second electromagnetic flowmeter, set a certain flow and pressure condition, and then open any one or more leakage points, and monitor the change of pipeline pressure value through the first pressure sensor, the second pressure sensor, the third pressure sensor, the fourth pressure sensor, the fifth pressure sensor, the sixth pressure sensor, the seventh pressure sensor, the eighth pressure sensor, the ninth pressure sensor, the tenth pressure sensor, the eleventh pressure sensor, and the twelfth pressure sensor. When the reduction in the pressure value is twice the difference between the minimum value of the pressure signal and the average value of the pressure signal when no leakage experiment occurs under the same flow and pressure conditions, leakage monitoring is achieved;

[0021] When determining the location of pipeline leakage, assume that the propagation speed of the negative pressure wave in the pipeline is a, P is the leakage point, the upstream pressure sensor of the leakage point P is A, the downstream pressure sensor of the leakage point is B, and the distance between the upstream pressure sensor A of the leakage point and the downstream pressure sensor B of the leakage point is L. When a leak is detected at point P on the pipeline, the negative pressure wave generated by the leak starts to propagate from the leakage point to both sides of the pipeline. However, due to the different distances from point P to the upstream and downstream sensors A and B, there is a time delay T from the same negative pressure waveform caused by the leak to the two sensors. d ; Assuming the fluid velocity is ν, and the distance between the upstream pressure sensor A and the calculated leakage point P is X, then:

[0022]

[0023] When a pipeline leaks, the relative error formula is used to calculate:

[0024]

[0025] Where X represents the calculated leakage point location, and X′ represents the actual leakage point location.

[0026] The time delay value T is obtained by fast Fourier transform dThe specific method includes the following steps: (1) signal acquisition: the upstream pressure sensor A and the downstream pressure sensor B acquire signal data; (2) preprocessing: the signal data acquired by the upstream pressure sensor A and the downstream pressure sensor B are subjected to low-pass filtering to remove high-frequency noise; (3) fast Fourier transform: the signals x(n) and y(n) acquired by the upstream pressure sensor A and the downstream pressure sensor B are subjected to fast Fourier transform (FFT), and x(n) and y(n) are converted from the time domain to the frequency domain to obtain frequency domain signals X(k) and Y(k), wherein n represents the time domain index, which represents the serial number of the time series; k represents the index in the frequency domain, which represents the serial number of the frequency component; (4) frequency domain cross-correlation: the cross-correlation function of the signal is calculated in the frequency domain, and the frequency domain signal X(k) is multiplied by the complex conjugate Y'(k) of the frequency domain signal Y(k), and then the inverse FFT is performed to obtain the cross-correlation function R xy (n); (5) Delay calculation: Identify the maximum value of the cross-correlation function, which corresponds to the time difference between the two signals; (6) Result output: Output the calculated time difference as the final delay value T d .

[0027] The specific operation process of the water hammer test is as follows: close the third butterfly valve to allow the return water to return to the water tank through the lower return pipe, close any leakage point, and realize the valve-off water hammer test; close the electric ball valve 35 through the air compressor to change the ball valve opening to 30°, 45°, 60°, and 90° within 1 second, thereby realizing the cut-off water hammer; monitor the change of pipeline pressure value through the first pressure sensor, the second pressure sensor, the third pressure sensor, the fourth pressure sensor, the fifth pressure sensor, the sixth pressure sensor, the seventh pressure sensor, the eighth pressure sensor, the ninth pressure sensor, the tenth pressure sensor, the eleventh pressure sensor, the twelfth pressure sensor and the first displacement sensor, the second displacement sensor, the third displacement sensor, and the fourth displacement sensor. When the pressure value rises to more than twice the original pressure within two seconds and a periodic pressure oscillation phenomenon occurs, that is, a continuous sinusoidal wave signal appears, and the pressure wave undergoes an attenuation process, the water hammer test is realized.

[0028] The beneficial effects of the present invention are:

[0029] (1) The greatest advantage of the device of the present invention is that the experimental system is safe and reliable, easy to operate, and can synchronously collect flow rates at multiple locations in the water pipeline and pressure signals at multiple locations upstream and downstream in real time. During the experiment, various measurement parameters remain stable, which can effectively ensure measurement accuracy and reduce experimental costs, providing support for the design and optimization of high-pressure water pipeline systems.

[0030] (2) The device of the present invention can transport up to 100m 3 / h water flow rate, the use of 304 stainless steel material is more in line with the actual application of the project, the pipeline has the advantages of pressure resistance and strong sealing.

[0031] (3) The device of the present invention uses a frequency conversion cabinet to directly electromagnetically control the flow of the water pump. The advantages of this technology are that the flow is easy to adjust, the response is rapid, and the adjustment range is wide. At the same time, centrifugal pumps, back pressure valves, butterfly valves, ball valves and other devices are used to coordinately adjust experimental parameters such as flow and pressure, and the pressure can be changed to 1MPa, which is conducive to studying leakage and water hammer phenomena under different pressure conditions. In addition, multiple leakage points are arranged along the water pipeline to repeatedly verify the research method. Provide support for high-pressure water pipeline leakage technology.

[0032] (4) The data of all pressure sensors, displacement sensors, electromagnetic flowmeters and other measuring instruments used in the device of the present invention are synchronously transmitted to the data acquisition system and can be monitored and saved in real time, which not only improves the accuracy of the measurement data but also makes the operation simple and saves time.

[0033] (5) The device of the present invention uses an electric ball valve to perform a valve closing experiment, which can change the ball valve opening within 0.5 seconds to produce an obvious water hammer phenomenon. Compared with the traditional manual change of the ball valve opening, the ball valve opening and the ball valve closing time can be controlled more accurately, reducing the experimental error.

[0034] (6) The device of the present invention has good repeatability and controllability. Researchers can conduct multiple experiments according to their needs and adjust and control the experimental conditions. Compared with conducting experiments in actual pipeline systems, the experimental platform is less expensive and easier to control and manage. In this way, more diverse data and results can be obtained, further deepening the understanding of water hammer and leakage behavior.

[0035] (7) The device of the present invention addresses the difficulty in building an experimental platform for long-distance high-pressure water pipelines and provides an experimental platform that can simulate water hammer and leakage at the same time. The device of the present invention provides a higher-precision measuring device, thereby achieving accurate recording and acquisition of water hammer and leakage-related data; at the same time, the device of the present invention uses an automatic exhaust valve and a manual exhaust valve for exhaust, thereby improving exhaust efficiency; high-pressure water delivery is often carried out in actual engineering. Since the size of the water pipeline is large, the device of the present invention is equipped with a back pressure valve, so that the maximum pressure of the experimental working condition reaches 1MPa. The pipeline diameter is DN100, the pipeline length is 200 meters, and the pipeline material is 304 stainless steel. Regardless of the pipeline diameter, length or material, it is more in line with the actual needs of the project, and it is more helpful for researchers to better understand the principles and characteristics of leakage and water hammer in high-pressure water pipelines. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a structural schematic diagram of a water hammer, leakage monitoring and positioning test device for a long-distance high-pressure water pipeline of the present invention;

[0037] Figure 2 It is the principle diagram of the Fast Fourier Transform (FFT) calculation of the cross-correlation function;

[0038] Figure 3 It is the principle diagram of locating water pipeline leakage;

[0039] Figure 4 The device of the present invention is used to study the change of pressure signal when a water pipeline leaks. The pipeline inlet flow rate Q = 15m 3 / h;

[0040] Figure 5 The device of the present invention is used to study the change of pressure signal when a water pipeline leaks. The pipeline inlet flow rate Q = 30m 3 / h;

[0041] Figure 6 The device of the present invention is used to study the change of pressure signal when a water pipeline leaks. The pipeline inlet flow rate Q = 50m 3 / h;

[0042] Figure 7 The device of the present invention is used to carry out the pressure pulsation experiment of the water hammer caused by valve closing in the water pipeline. The pipeline inlet flow rate Q = 15m 3 / h;

[0043] Figure 8 The device of the present invention is used to carry out the pressure pulsation experiment of the water hammer caused by closing the valve of the water pipeline. The pipeline inlet flow rate Q = 30m 3 / h;

[0044] Fig. 9 The device of the present invention is used to carry out the pressure pulsation experiment of the water hammer caused by closing the valve of the water pipeline. The pipeline inlet flow rate Q = 50m 3 / h;

[0045] In the figure, 1. water tank, 2. centrifugal pump, 3. ball valve, 4. first butterfly valve, 5. first electromagnetic flowmeter, 6. first pressure sensor, 7. first leakage point, 8. second pressure sensor, 9. first displacement sensor, 10. third pressure sensor, 11. second leakage point, 12. fourth pressure sensor, 13. second displacement sensor, 14. fifth pressure sensor, 15. third leakage point, 16. sixth pressure sensor, 17. first automatic exhaust valve, 18. second automatic exhaust valve, 19. third automatic exhaust valve, 20. fourth automatic exhaust valve, 2 1. The seventh pressure sensor, 22. The fourth leakage point, 23. The eighth pressure sensor, 24. The third displacement sensor, 25. The ninth pressure sensor, 26. The fourth displacement sensor, 27. The fifth leakage point, 28. The tenth pressure sensor, 29. The eleventh pressure sensor, 30. The sixth leakage point, 31. The twelfth pressure sensor, 32. The second electromagnetic flowmeter, 33. The manual exhaust valve, 34. The second butterfly valve, 35. The electric ball valve, 36. The one-way valve, 37. The first compensator, 38. The third butterfly valve, 39. The back pressure valve, 40. The second compensator. DETAILED DESCRIPTION

[0046] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] The present invention provides a long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device, such as Figure 1 As shown, it includes a water tank 1, and also includes an outlet side experimental unit, a return water side main line experimental unit and a return water side branch line experimental unit. The outlet side experimental unit and the return water side branch line experimental unit are both connected to the return water side main line experimental unit, and the outlet side experimental unit, the return water side main line experimental unit and the return water side branch line experimental unit are all connected to the water tank 1.

[0048] The outlet side experimental unit includes a centrifugal pump 2, a ball valve 3, a first butterfly valve 4, a first electromagnetic flowmeter 5, a first displacement sensor 9, and a second displacement sensor 13, which are sequentially connected through pipelines. The second displacement sensor 13 is connected to the return side main road experimental unit through a pipeline. The pipeline connecting the second displacement sensor 13 and the return side main road experimental unit is sequentially provided with a fifth pressure sensor 14, a plurality of third leakage points 15, a sixth pressure sensor 16, a first automatic exhaust valve 17, and a second automatic exhaust valve 18 according to the water flow direction;

[0049] A first pressure sensor 6 and a second pressure sensor 8 are provided on the pipeline between the first electromagnetic flowmeter 5 and the first displacement sensor 9, and a plurality of first leakage points 7 are provided on the pipeline between the first pressure sensor 6 and the second pressure sensor 8;

[0050] A third pressure sensor 10, a plurality of second leakage points 11 and a fourth pressure sensor 12 are arranged on the pipeline between the first displacement sensor 9 and the second displacement sensor 13 according to the water flow direction.

[0051] The main experimental unit on the return water side includes a third displacement sensor 24, a fourth displacement sensor 26, a second electromagnetic flowmeter 32, a manual exhaust valve 33, a second butterfly valve 34, an electric ball valve 35, a one-way valve 36 and a first compensator 37 which are sequentially connected through pipelines. The first compensator 37 is connected to the water tank 1 through a pipeline; the third displacement sensor 24 is connected to the pipeline where the second automatic exhaust valve 18 is located through a pipeline; the pipeline between the second automatic exhaust valve 18 and the third displacement sensor 24 is sequentially provided with a third automatic exhaust valve 19, a fourth automatic exhaust valve 20, The seventh pressure sensor 21, several fourth leakage points 22 and the eighth pressure sensor 23; the ninth pressure sensor 25 is arranged on the pipeline between the third displacement sensor 24 and the fourth displacement sensor 26; the pipeline between the fourth displacement sensor 26 and the second electromagnetic flowmeter 32 is provided with several fifth leakage points 27, the tenth pressure sensor 28, the eleventh pressure sensor 29, several sixth leakage points 30 and the twelfth pressure sensor 31 in sequence according to the water flow direction; the pipeline between the manual exhaust valve 33 and the second butterfly valve 34 is connected to the return side branch experimental unit.

[0052] The return side branch experimental unit connection includes a third butterfly valve 38, a back pressure valve 39 and a second compensator 40 which are connected in sequence through a pipeline according to the water flow direction. The second compensator 40 is connected to the water tank 1 through a pipeline, and the second compensator 40 is arranged close to the water tank 1.

[0053] In the long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device of the present invention, the water tank 1 is an open water tank, the water tank 1 is connected to the centrifugal pump 2 through a flange, the output power of the centrifugal pump 2 is controlled by the frequency conversion cabinet, and the flow rate of the experimental device can be changed. The centrifugal pump 2 is connected to the ball valve 3 and the first butterfly valve 4 in sequence through the flange, and the first butterfly valve 4 is connected to the first electromagnetic flowmeter 5 through a pipeline. The flow rate on the water inlet side can be directly seen through the first electromagnetic flowmeter 5, and the NI acquisition card can also be connected to the NI LabVIEW software displays real-time flow. The first electromagnetic flowmeter 5 is connected to the first pressure sensor 6. The pressure sensor is connected to the computer acquisition system for real-time monitoring of the pressure signal at that point. Four leakage points are arranged between the first pressure sensor 6 and the second pressure sensor 8. Each leakage point is 2 meters apart to simulate pipeline leakage in production and life. The leakage point hole diameter is 13mm and is threadedly connected to the bottom of the pipeline. The second pressure sensor 8 is connected to the first displacement sensor 9. The first displacement sensor 9 is connected to the computer acquisition system for sampling and obtaining the vibration signal of the pipeline system under transient flow conditions, and obtaining the degree of change of the pressure signal during the water hammer experiment. The third pressure sensor is connected behind the first displacement sensor 9. The device 10 is provided with 7 leakage holes with a diameter of 13 mm between the third pressure sensor 10 and the fourth pressure sensor 12, and the intervals are 2 meters. The fourth pressure sensor 12 is connected to the second displacement sensor 13, and the second displacement sensor 13 is connected to the fifth pressure sensor 14 behind it. Seven leakage holes with a diameter of 13 mm are provided between the fifth pressure sensor 14 and the sixth pressure sensor 16, and the intervals are 2 meters. Then, the pipeline is followed to the top of the pipeline, and the first automatic exhaust valve 17 and the second automatic exhaust valve 18 are provided and connected to the pipeline with flanges, so as to automatically remove the air in the pipeline during the experimental preparation stage and the experimental operation process. The presence of some air in the pipeline will cause the pipeline to vibrate slightly, thereby affecting the accuracy of the pressure signal.

[0054] The third automatic exhaust valve 19 and the fourth automatic exhaust valve 20 of the return water side pipeline are connected on the pipeline by flanges, and the seventh pressure sensor 21 is connected further down the pipeline. Seven fourth leakage points 22 with a diameter of 13 mm are arranged between the seventh pressure sensor 21 and the eighth pressure sensor 23 at intervals of 2 meters. The eighth pressure sensor 23 is connected to the third displacement sensor 24, and the third displacement sensor 24 is connected to the ninth pressure sensor 25. A fourth displacement sensor 26 and seven fifth leakage points with a diameter of 13 mm are arranged between the ninth pressure sensor 25 and the tenth pressure sensor 28. The interval between the leakage points 27 is 2 meters. Further down the pipeline, the tenth pressure sensor 28 is connected to the eleventh pressure sensor 29. Four leakage holes with a diameter of 13 mm are set between the eleventh pressure sensor 29 and the twelfth pressure sensor 31, and the intervals are 2 meters. The twelfth pressure sensor 31 is connected to the second electromagnetic flowmeter 32 to monitor the flow rate on the return water side. It can also be connected to the NI acquisition card to display the real-time flow rate on the return water side on the computer acquisition system. A manual exhaust valve 33 is connected to the electromagnetic flowmeter. When there is gas in the pipeline, the exhaust valve is manually opened to exhaust the air.

[0055] The manual exhaust valve 33 of the lower return water pipeline is connected to the second butterfly valve 34 through a three-way connection, and then connected to the electric ball valve 35. The electric ball valve can be controlled by an external air compressor to control the opening of the ball valve, so that the opening of the ball valve can be changed to 30°, 45°, 60°, and 90° within 1 second, thereby generating water hammer. The electric ball valve 35 is connected to a one-way valve 36 behind it. The function of the one-way valve is to protect the electric ball valve 35 during the water hammer experiment and prevent the electric ball valve 35 from being impacted. The one-way valve 36 is connected to the first compensator 37 behind it and then returns to the water tank 1. The function of the compensator is that when there is pressure fluctuation or pressure shock in the pipeline system, the compensator can buffer these pressure changes and reduce the impact and damage to the pipeline and related equipment. The compensator can also have a certain shock absorption ability, thereby reducing noise and extending the service life of the pipeline equipment.

[0056] The manual exhaust valve 33 of the upper return water pipeline is connected to the third butterfly valve 38 through a tee, and then connected to the back pressure valve 39. The function of the back pressure valve is to prevent the fluid from flowing back and protect the equipment. The back pressure valve can increase the pipeline pressure to 1MPa, which can make the pipeline operation more stable and make the leakage signal more obvious, making it convenient to monitor the leakage signal. The back pressure valve 39 is connected to the second compensator 40 and then returns to the water tank 1.

[0057] The present invention also provides a method for using a long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device. When using the long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device, when performing leakage monitoring and positioning experiments, close the second butterfly valve 34 and the electric ball valve 35, open the third butterfly valve 38 and the back pressure valve 39, so that the return side water returns to the water tank 1 through the return side branch experimental unit, and then open any leakage point to monitor the change of the pipeline pressure value, so as to realize leakage monitoring and positioning;

[0058] When doing a water hammer test, close the second butterfly valve 34 and the back pressure valve 39, open the second butterfly valve 34 and the electric ball valve 35, so that the return water returns to the water tank 1 through the return water main line test unit, and then change the opening of the electric ball valve 35 to monitor the change of the pipeline pressure value to achieve a cut-off water hammer test; or close any leakage point to monitor the change of the pipeline pressure value to achieve a valve-off water hammer test;

[0059] The specific operation process of the leakage monitoring experiment is as follows: close the second butterfly valve 34 and the electric ball valve 35, so that the return side water returns to the water tank 1 through the return side branch experimental unit, manually change the pipeline pressure by increasing the pipeline pressure by 0.1MPa every ten seconds through the back pressure valve 39, change the power of the centrifugal pump 2 to change the pipeline flow, observe the flow change through the first electromagnetic flowmeter 5 and the second electromagnetic flowmeter 32, set a certain flow and pressure condition, and then open any one or more leakage points (specifically, the optional leakage points are: the first leakage point 7, the second leakage point 11, the third leakage point 15, the fourth leakage point 2 2. The fifth leakage point 27 and the sixth leakage point 30) are monitored by the first pressure sensor 6, the second pressure sensor 8, the third pressure sensor 10, the fourth pressure sensor 12, the fifth pressure sensor 14, the sixth pressure sensor 16, the seventh pressure sensor 21, the eighth pressure sensor 23, the ninth pressure sensor 25, the tenth pressure sensor 28, the eleventh pressure sensor 29 and the twelfth pressure sensor 31. When the decrease in the pressure value is twice the difference between the minimum value of the pressure signal and the average value of the pressure signal in the experiment without leakage under the same flow and pressure conditions, leakage monitoring is achieved;

[0060] The specific operation process of the water hammer test is as follows: close the third butterfly valve 38, so that the return side water returns to the water tank 1 through the lower return pipe, close any leakage point (specifically, the selectable leakage points are: the first leakage point 7, the second leakage point 11, the third leakage point 15, the fourth leakage point 22, the fifth leakage point 27, and the sixth leakage point 30) to realize the valve closing water hammer test; close the electric ball valve 35 through the air compressor to change the ball valve opening to 30°, 45°, 60°, and 90° within 1 second, thereby generating a cut-off water hammer; The force sensor 12, the fifth pressure sensor 14, the sixth pressure sensor 16, the seventh pressure sensor 21, the eighth pressure sensor 23, the ninth pressure sensor 25, the tenth pressure sensor 28, the eleventh pressure sensor 29, the twelfth pressure sensor 31 and the first displacement sensor 9, the second displacement sensor 13, the third displacement sensor 24, and the fourth displacement sensor 26 monitor changes in pipeline pressure values. When the pressure value rises to more than twice the original pressure within two seconds and periodic pressure oscillations occur, a continuous sinusoidal wave signal appears, and the pressure wave undergoes an attenuation process, a water hammer experiment is achieved.

[0061] The specific preparations before doing a leakage monitoring experiment or a water hammer experiment are as follows: first close all leakage points, open the first butterfly valve 4, the second butterfly valve 34, the third butterfly valve 38, open the ball valve 3, the electric ball valve 35, and the back pressure valve 39, open the centrifugal pump 2 pipeline to inlet water, the frequency converter can change the power of the centrifugal pump 2 and thus change the pipeline flow, and observe the flow change through the first electromagnetic flowmeter 5 and the second electromagnetic flowmeter 32, so as to realize leakage and water hammer experiments under different flow conditions, the first automatic exhaust valve 17, the second automatic exhaust valve 18, the third automatic exhaust valve 19, and the fourth automatic exhaust valve 20 are arranged at the upper end of the pipeline. When gas enters the pipeline, automatic exhaust is realized, and at the same time, the manual exhaust valve 33 can be opened for manual exhaust. After the air in the pipeline is exhausted, the manual exhaust valve 33 is closed, and the preparations are completed.

[0062] Centrifugal pump 2 uses a single-stage single-suction centrifugal pump with model 100-315A; the electromagnetic flowmeter uses an intelligent electromagnetic flowmeter with model KDLD-100; the power supply is 24VAC / DC, and the working pressure is 1.6MPa; the pressure sensor model is HM90A-H2-3-V2-F2-W1, the measurable pressure range is 0~2MPa, and the sampling frequency is 2048Hz; the electric ball valve model is Q941F-16C; the displacement sensor model is PCB-333B30, and the sampling frequency is 2048Hz; the automatic exhaust valve model is DN100-10 / 16; the back pressure valve model is QSBF-S100 / 0.6.

[0063] Study pipeline leak location, such as Figure 3As shown in the figure, let the propagation speed of the negative pressure wave in the pipeline be a, P be the leakage point, the upstream pressure sensor of the leakage point P be A (A and B are sensors in close contact with the outer wall of the pipeline), the downstream pressure sensor of the leakage point P be B, and the distance between the upstream pressure sensor A of the leakage point P and the downstream pressure sensor B of the leakage point P be L. When a leak is detected at point P on the pipeline, the negative pressure wave generated by the leak starts to propagate from the leakage point to both sides of the pipeline, but because the distances from point P to the upstream and downstream sensors A and B are different, there is a time delay value T between the time when the same negative pressure waveform caused by the leak reaches the two sensors. d Assuming the fluid velocity is ν, and the distance between the upstream pressure sensor A and the calculated leakage point P is X, we have:

[0064]

[0065] After a pipeline leak occurs, in order to measure the accuracy of positioning monitoring using pipeline leaks, the relative error formula is used to calculate:

[0066]

[0067] Where X represents the calculated leakage point location, and X′ represents the actual leakage point location.

[0068] To further verify the accuracy of pipeline leak location, the present invention uses fast Fourier transform (FFT) to calculate the cross-correlation function, and use it to determine the time delay in pipeline leak detection. In various signal processing applications, such as radar, acoustic positioning, communication systems and pipeline leak detection, it is very important to accurately measure the time difference or delay between two signals. Traditional delay estimation methods, such as direct correlation methods, may be limited by computational complexity and processing time. Fast Fourier transform (FFT) provides an effective way to significantly accelerate the process of delay estimation while maintaining high accuracy.

[0069] Figure 2 This is the principle diagram of Fast Fourier Transform (FFT), such as Figure 2 As shown, the delay value T is obtained by fast Fourier transform (FFT) dThe method includes the following steps: (1) Signal acquisition: The upstream pressure sensor A and the downstream pressure sensor B collect signal data. (2) Preprocessing: The signal data collected by the upstream pressure sensor A and the downstream pressure sensor B are low-pass filtered to remove high-frequency noise and improve the clarity and reliability of the signal. (3) Fast Fourier transform: The signals x(n) and y(n) collected by the upstream pressure sensor A and the downstream pressure sensor B are fast Fourier transformed (FFT), and x(n) and y(n) are converted from the time domain to the frequency domain respectively to obtain frequency domain signals X(k) and Y(k), where n represents the time domain index, which represents the serial number of the time series; k represents the index in the frequency domain, which represents the serial number of the frequency component. (4) Frequency domain cross-correlation: The cross-correlation function of the signal is calculated in the frequency domain, and the frequency domain signal X(k) is multiplied by the complex conjugate Y'(k) of the frequency domain signal Y(k), and then an inverse FFT (IFFT) is performed to obtain the cross-correlation function R xy (n). (5) Delay calculation: Identify the maximum value of the cross-correlation function, which corresponds to the time difference between the two signals. (6) Result output: Output the calculated time difference as the final delay value T d .

[0070] Figures 4 to 6 The change of pressure signal when using the experimental device of the present invention to simulate pipeline leakage, the x-axis is the sample collected over time, set to collect 2000 samples per second, and the y-axis is the pressure. It is set to open the leaking valve at the 10th second to cause leakage, and the pressure begins to decrease. When the volume flow rate Q = 15m 3 / h, the cross-correlation function is calculated by FFT to obtain the time delay T d =0.014952s, and the leak point position is calculated to be 1.886m. The actual leak hole X' is located 2m from the upstream pressure sensor A (i.e., pressure sensor 28), so the positioning error of the leak hole is 5.7%. 3 / h, the cross-correlation function is calculated by FFT to obtain the time delay T d =0.014916s, and the leak point position is calculated to be 1.914m. The actual leak hole X' is located 2m from the upstream pressure sensor A (i.e., pressure sensor 28), so the positioning error of the leak hole is 4.3%. When the volume flow rate Q = 50m 3 / h, the cross-correlation function is calculated by FFT to obtain the time delay T dThe leakage point position is 1.918m, and the actual leakage hole X' is located 2m from the upstream pressure sensor A (i.e., the pressure sensor 28), so the positioning error of the leakage hole is 4.1%. It can be seen that the leakage monitoring accuracy of the invention is high, and the accuracy increases with the increase of flow rate.

[0071] The device can simulate leakage in the pipeline system. By controlling different leakage conditions and parameters, the impact of leakage on the system, such as leakage flow, leakage pressure, etc., can be studied and analyzed. The experimental platform can be used to test the leakage speed, leakage range and the impact of leakage on equipment and the environment under different leakage conditions, thereby helping the actual engineering design and improvement of leakage control measures, and improving the safety and environmental protection of the system.

[0072] Figure 7 to Figure 9 In order to use the device of the present invention to carry out the pressure pulsation experiment of water hammer when the valve is closed in the water pipeline, the x-axis is the sample collected over time, and 2000 samples are collected per second, and the y-axis is the pressure. In order to more intuitively reflect the relationship between the pressure pulsation after the valve is closed and the pipeline flow rate, the valve closing pressure signals under different flow rates are extracted and compared and analyzed, that is, the pipeline inlet flow rate is 15m 3 / h、30m 3 / h、50m 3 / h, set the closing time of the electric ball valve to 1s. Figures 5 to 7 The pressure fluctuations shown by the valve closing show very regular sinusoidal fluctuations with great intensity. The flow rate is 30m 3 / h when the maximum value of the valve closing pressure pulsation is greater than 1.3 times the pressure value during stable flow. The pipeline system is significantly impacted, and the harsh sound during the experiment reflects the power of water hammer fluctuations. The comparison flow rate is 15m 3 / h and 30m 3 / h, the fluctuation amplitude increases further with the increase of flow rate. 3 / h, the pressure pulsation amplitude reaches the maximum, but the fluctuation period is significantly shortened; the amplitude of the valve closing pressure fluctuation increases with the increase of flow rate, among which the maximum value increases and the minimum value decreases.

[0073] According to the valve closing water hammer experiment, when the flow rate increases, the pressure oscillation amplitude in the pipeline also increases, but the pressure vibration period decreases, the water hammer wave gradually decreases and finally dissipates, the pipeline pressure returns to normal, and there is no negative pressure in the whole process. The increase in flow rate will improve the safety of operation, but when the valve is closed in an emergency, the larger flow rate will lead to greater pressure shock and potential risks.

[0074] The device of the present invention can locate pipeline leakage more accurately and perform water hammer experiments at the same time. Compared with existing devices, it has many advantages such as low experimental cost, simple operation, stable measurement parameters, high instrument accuracy, stable and safe operation, etc.

[0075] The device of the present invention discloses a long-distance (hundred-meter level), large-caliber (DN100) high-pressure water pipeline water hammer, leakage monitoring and positioning test device; the main line test unit is equipped with a back pressure valve, which can increase the pressure in the pipe to 1MPa; the main line test unit is equipped with a one-way valve and a compensator to reduce the impact and damage of pressure fluctuations on related equipment such as water pumps. The device can conduct leakage positioning experiments on high-pressure water pipelines, and can also conduct valve-off water hammer and flow-cutting water hammer experiments. It not only solves the problem of small leaks in the high-pressure water delivery process in the prior art that are difficult to monitor and locate, but also solves the problem of difficulty in high-precision acquisition of pressure signals in water hammer experiments and the impact damage caused by water hammer experiments to equipment, and is convenient for analyzing the coupling relationship between water hammer and leakage.

[0076] The device of the present invention can study and analyze the causes, characteristics and effects of water hammer by simulating the fluid movement in the pipeline system. The water hammer pressure and shock wave propagation speed under different operating conditions can be tested through the experimental device, thereby helping the actual engineering design and optimization of the pipeline system, reducing the damage of water hammer to pipelines and equipment, and improving the stability and safety of the system.

[0077] Example 1

[0078] The present invention provides a long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device, such as Figure 1 As shown, it includes a water tank 1, and also includes an outlet side experimental unit, a return water side main line experimental unit and a return water side branch line experimental unit. The outlet side experimental unit and the return water side branch line experimental unit are both connected to the return water side main line experimental unit, and the outlet side experimental unit, the return water side main line experimental unit and the return water side branch line experimental unit are all connected to the water tank 1.

[0079] Example 2

[0080] The present invention provides a long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device, such as Figure 1 As shown, it includes a water tank 1, and also includes an outlet side experimental unit, a return water side main line experimental unit and a return water side branch line experimental unit. The outlet side experimental unit and the return water side branch line experimental unit are both connected to the return water side main line experimental unit, and the outlet side experimental unit, the return water side main line experimental unit and the return water side branch line experimental unit are all connected to the water tank 1.

[0081] The outlet side experimental unit includes a centrifugal pump 2, a ball valve 3, a first butterfly valve 4, a first electromagnetic flowmeter 5, a first displacement sensor 9, and a second displacement sensor 13, which are sequentially connected through pipelines. The second displacement sensor 13 is connected to the return side main road experimental unit through a pipeline. The pipeline connecting the second displacement sensor 13 and the return side main road experimental unit is sequentially provided with a fifth pressure sensor 14, a plurality of third leakage points 15, a sixth pressure sensor 16, a first automatic exhaust valve 17, and a second automatic exhaust valve 18 according to the water flow direction;

[0082] A first pressure sensor 6 and a second pressure sensor 8 are provided on the pipeline between the first electromagnetic flowmeter 5 and the first displacement sensor 9, and a plurality of first leakage points 7 are provided on the pipeline between the first pressure sensor 6 and the second pressure sensor 8;

[0083] A third pressure sensor 10, a plurality of second leakage points 11 and a fourth pressure sensor 12 are arranged on the pipeline between the first displacement sensor 9 and the second displacement sensor 13 according to the water flow direction.

[0084] Example 3

[0085] The present invention provides a long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device, such as Figure 1 As shown, it includes a water tank 1, and also includes an outlet side experimental unit, a return water side main line experimental unit and a return water side branch line experimental unit. The outlet side experimental unit and the return water side branch line experimental unit are both connected to the return water side main line experimental unit, and the outlet side experimental unit, the return water side main line experimental unit and the return water side branch line experimental unit are all connected to the water tank 1.

[0086] The outlet side experimental unit includes a centrifugal pump 2, a ball valve 3, a first butterfly valve 4, a first electromagnetic flowmeter 5, a first displacement sensor 9, and a second displacement sensor 13, which are sequentially connected through pipelines. The second displacement sensor 13 is connected to the return side main road experimental unit through a pipeline. The pipeline connecting the second displacement sensor 13 and the return side main road experimental unit is sequentially provided with a fifth pressure sensor 14, a plurality of third leakage points 15, a sixth pressure sensor 16, a first automatic exhaust valve 17, and a second automatic exhaust valve 18 according to the water flow direction;

[0087] A first pressure sensor 6 and a second pressure sensor 8 are provided on the pipeline between the first electromagnetic flowmeter 5 and the first displacement sensor 9, and a plurality of first leakage points 7 are provided on the pipeline between the first pressure sensor 6 and the second pressure sensor 8;

[0088] A third pressure sensor 10, a plurality of second leakage points 11 and a fourth pressure sensor 12 are arranged on the pipeline between the first displacement sensor 9 and the second displacement sensor 13 according to the water flow direction.

[0089] The main experimental unit on the return water side includes a third displacement sensor 24, a fourth displacement sensor 26, a second electromagnetic flowmeter 32, a manual exhaust valve 33, a second butterfly valve 34, an electric ball valve 35, a one-way valve 36 and a first compensator 37 which are sequentially connected through pipelines. The first compensator 37 is connected to the water tank 1 through a pipeline; the third displacement sensor 24 is connected to the pipeline where the second automatic exhaust valve 18 is located through a pipeline; the pipeline between the second automatic exhaust valve 18 and the third displacement sensor 24 is sequentially provided with a third automatic exhaust valve 19, a fourth automatic exhaust valve 20, The seventh pressure sensor 21, several fourth leakage points 22 and the eighth pressure sensor 23; the ninth pressure sensor 25 is arranged on the pipeline between the third displacement sensor 24 and the fourth displacement sensor 26; the pipeline between the fourth displacement sensor 26 and the second electromagnetic flowmeter 32 is provided with several fifth leakage points 27, the tenth pressure sensor 28, the eleventh pressure sensor 29, several sixth leakage points 30 and the twelfth pressure sensor 31 in sequence according to the water flow direction; the pipeline between the manual exhaust valve 33 and the second butterfly valve 34 is connected to the return side branch experimental unit.

[0090] The return side branch experimental unit connection includes a third butterfly valve 38, a back pressure valve 39 and a second compensator 40 which are connected in sequence through a pipeline according to the water flow direction. The second compensator 40 is connected to the water tank 1 through a pipeline, and the second compensator 40 is arranged close to the water tank 1.

[0091] The method of using the above-mentioned long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device is specifically as follows:

[0092] When doing leakage monitoring and positioning experiments, close the second butterfly valve 34 and the electric ball valve 35, open the third butterfly valve 38 and the back pressure valve 39, so that the return water returns to the water tank 1 through the return water branch experimental unit, and then open any leakage point to monitor the change of pipeline pressure value to achieve leakage monitoring and positioning;

[0093] When doing a water hammer test, close the third butterfly valve 38 and the back pressure valve 39, open the second butterfly valve 34 and the electric ball valve 35, so that the return side water returns to the water tank 1 through the return side main line test unit, and then change the opening of the electric ball valve 35 to monitor the change of the pipeline pressure value to achieve a cut-off water hammer test; or close any leakage point to monitor the change of the pipeline pressure value to achieve a valve-off water hammer test.

Claims

1. Long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device, characterized in that: The invention comprises a water tank (1), and also comprises an outlet side experimental unit, a return side main line experimental unit and a return side branch line experimental unit. The outlet side experimental unit and the return side branch line experimental unit are both connected to the return side main line experimental unit. The outlet side experimental unit, the return side main line experimental unit and the return side branch line experimental unit are all connected to the water tank (1).

2. The long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device according to claim 1 is characterized in that: The outlet side experimental unit comprises a centrifugal pump (2), a ball valve (3), a first butterfly valve (4), a first electromagnetic flowmeter (5), a first displacement sensor (9), and a second displacement sensor (13) which are sequentially connected via a pipeline; the second displacement sensor (13) is connected to the return side main path experimental unit via a pipeline; a fifth pressure sensor (14), a plurality of third leakage points (15), a sixth pressure sensor (16), a first automatic exhaust valve (17), and a second automatic exhaust valve (18) are sequentially arranged on the pipeline connecting the second displacement sensor (13) and the return side main path experimental unit according to the water flow direction; A first pressure sensor (6) and a second pressure sensor (8) are provided on the pipeline between the first electromagnetic flowmeter (5) and the first displacement sensor (9), and a plurality of first leakage points (7) are provided on the pipeline between the first pressure sensor (6) and the second pressure sensor (8); A third pressure sensor (10), a plurality of second leakage points (11) and a fourth pressure sensor (12) are arranged on the pipeline between the first displacement sensor (9) and the second displacement sensor (13) according to the water flow direction.

3. The long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device according to claim 2 is characterized in that: The return water side main line experimental unit comprises a third displacement sensor (24), a fourth displacement sensor (26), a second electromagnetic flowmeter (32), a manual exhaust valve (33), a second butterfly valve (34), an electric ball valve (35), a check valve (36) and a first compensator (37) which are sequentially connected through a pipeline; the first compensator (37) is connected to the water tank (1) through a pipeline; the third displacement sensor (24) is connected to the pipeline where the second automatic exhaust valve (18) is located through a pipeline; the pipeline between the second automatic exhaust valve (18) and the third displacement sensor (24) is sequentially provided with a third automatic exhaust valve (19), a fourth automatic exhaust valve (20) and a second automatic exhaust valve (21). ), a seventh pressure sensor (21), a plurality of fourth leakage points (22) and an eighth pressure sensor (23); a ninth pressure sensor (25) is arranged on the pipeline between the third displacement sensor (24) and the fourth displacement sensor (26); a plurality of fifth leakage points (27), a tenth pressure sensor (28), an eleventh pressure sensor (29), a plurality of sixth leakage points (30) and a twelfth pressure sensor (31) are arranged on the pipeline between the fourth displacement sensor (26) and the second electromagnetic flowmeter (32) in sequence according to the direction of water flow; and the pipeline between the manual exhaust valve (33) and the second butterfly valve (34) is connected to the return side branch experimental unit.

4. The long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device according to claim 3 is characterized in that: The return water side branch experimental unit is connected to a third butterfly valve (38), a back pressure valve (39) and a second compensator (40) which are connected in sequence through a pipeline according to the direction of water flow. The second compensator (40) is connected to the water tank (1) through a pipeline, and the second compensator (40) is arranged close to the water tank (1).

5. The method for using the long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device according to any one of claims 1 to 4, characterized in that: Specifically: When conducting a leakage monitoring and positioning experiment, the second butterfly valve (34) and the electric ball valve (35) are closed, and the third butterfly valve (38) and the back pressure valve (39) are opened, so that the return water returns to the water tank (1) through the return water branch experimental unit, and then any leakage point is opened to monitor the change of the pipeline pressure value to achieve leakage monitoring and positioning; When performing a water hammer test, the third butterfly valve (38) and the back pressure valve (39) are closed, and the second butterfly valve (34) and the electric ball valve (35) are opened, so that the return water returns to the water tank (1) through the return water main line test unit, and then the opening of the electric ball valve (35) is changed to monitor the change of the pipeline pressure value to achieve a cut-off water hammer test; or any leakage point is closed to monitor the change of the pipeline pressure value to achieve a valve-off water hammer test.

6. The method for using the long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device according to claim 5 is characterized in that: The specific operation process of the leakage monitoring experiment is as follows: close the second butterfly valve (34) and the electric ball valve (35), so that the return side water returns to the water tank (1) through the return side branch experimental unit, manually change the pipeline pressure by increasing the pipeline pressure by 0.1 MPa every ten seconds through the back pressure valve (39), change the power of the centrifugal pump (2) to change the pipeline flow, observe the flow change through the first electromagnetic flowmeter (5) and the second electromagnetic flowmeter (32), set a certain flow and pressure condition, and then open any one or more leakage points, and observe the leakage through the first pressure sensor (6) and the second pressure sensor (32). The force sensor (8), the third pressure sensor (10), the fourth pressure sensor (12), the fifth pressure sensor (14), the sixth pressure sensor (16), the seventh pressure sensor (21), the eighth pressure sensor (23), the ninth pressure sensor (25), the tenth pressure sensor (28), the eleventh pressure sensor (29), and the twelfth pressure sensor (31) monitor changes in pipeline pressure values. When the pressure value decreases by twice the difference between the minimum value of the pressure signal and the average value of the pressure signal in a non-leakage experiment under the same flow rate and pressure conditions, leakage monitoring is achieved; When determining the location of pipeline leakage, assume that the propagation speed of the negative pressure wave in the pipeline is a, P is the leakage point, the upstream pressure sensor of the leakage point P is A, the downstream pressure sensor of the leakage point is B, and the distance between the upstream pressure sensor A of the leakage point and the downstream pressure sensor B of the leakage point is L. When a leak is detected at point P on the pipeline, the negative pressure wave generated by the leak starts to propagate from the leakage point to both sides of the pipeline. However, due to the different distances from point P to the upstream and downstream sensors A and B, there is a time delay value T from the same negative pressure waveform caused by the leak to the two sensors. d ; Assuming the fluid velocity is ν, and the distance between the upstream pressure sensor A and the calculated leakage point P is X, then: When a pipeline leaks, the relative error formula is used to calculate: Where X represents the calculated leakage point location, and X′ represents the actual leakage point location.

7. The method for using the long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device according to claim 6 is characterized in that: The time delay value T is obtained by fast Fourier transform d The specific method includes the following steps: (1) signal acquisition: the upstream pressure sensor A and the downstream pressure sensor B acquire signal data; (2) preprocessing: the signal data acquired by the upstream pressure sensor A and the downstream pressure sensor B are subjected to low-pass filtering to remove high-frequency noise; (3) fast Fourier transform: the signals x(n) and y(n) acquired by the upstream pressure sensor A and the downstream pressure sensor B are subjected to fast Fourier transform (FFT), and x(n) and y(n) are converted from the time domain to the frequency domain to obtain frequency domain signals X(k) and Y(k), wherein n represents the time domain index, which represents the serial number of the time series; k represents the index in the frequency domain, which represents the serial number of the frequency component; (4) frequency domain cross-correlation: the cross-correlation function of the signal is calculated in the frequency domain, and the frequency domain signal X(k) is multiplied by the complex conjugate Y'(k) of the frequency domain signal Y(k), and then the inverse FFT is performed to obtain the cross-correlation function R xy (n); (5) Delay calculation: Identify the maximum value of the cross-correlation function, which corresponds to the time difference between the two signals; (6) Result output: Output the calculated time difference as the final delay value T d .

8. The method for using the long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device according to claim 5, characterized in that: The specific operation flow of the water hammer test is as follows: close the third butterfly valve (38) to allow the return water to return to the water tank through the lower return pipe, close any leakage point, and realize the valve-off water hammer test; close the electric ball valve 35 through the air compressor to change the ball valve opening to 30°, 45°, 60°, and 90° within 1 second, thereby realizing the cut-off water hammer; and detect the flow of the water hammer through the first pressure sensor (6), the second pressure sensor (8), the third pressure sensor (10), the fourth pressure sensor (12), the fifth pressure sensor (14), the sixth pressure sensor (16), and the seventh pressure sensor (17). The device (21), the eighth pressure sensor (23), the ninth pressure sensor (25), the tenth pressure sensor (28), the eleventh pressure sensor (29), the twelfth pressure sensor (31), the first displacement sensor (9), the second displacement sensor (13), the third displacement sensor (24), and the fourth displacement sensor (26) monitor the change of the pipeline pressure value. When the pressure value rises to more than twice the original pressure within two seconds and a periodic pressure oscillation phenomenon occurs, that is, a continuous sinusoidal wave signal appears, and the pressure wave undergoes an attenuation process, a water hammer experiment is achieved.

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