Long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device and method

Abstract

The present invention discloses a device for monitoring and locating water hammer and leakage in long-distance, high-pressure water transmission pipelines. The device comprises a water tank, an outlet test unit, a return water main test unit, and a return water branch test unit. The outlet test unit and the return water branch test unit are all connected to the return water main test unit, and the outlet test unit, the return water main test unit, and the return water branch test unit are all connected to the water tank. This device solves the problems of existing testing and experimental technologies in which small leaks occurring during high-pressure water transmission are difficult to monitor, as well as the problems of insufficient accuracy in signal acquisition during water hammer testing and damage to equipment caused by impact during water hammer testing. The present invention also discloses a method for using the device for monitoring and locating water hammer and leakage in long-distance, high-pressure water transmission pipelines.

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 Pipelines [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, long-distance high-pressure pipeline water transmission still has some problems that need to be solved. 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 Long-distance Water Transmission Hydraulic Control [J]. Journal of Hydraulic Engineering, 2016, 47(03): 424-435). In addition, due to the large proportion of multi-level water supply systems, and their characteristics of long pipelines and large terrain undulations, water hammer is more likely to occur than straight pipelines. Sudden accidents such as water pump start-up and shutdown, improper valve operation, and sudden power outages will all cause water hammer to varying degrees. Water hammer not only damages the equipment in the water supply system, but may also cause the internal pressure of the pipeline to be too high and rupture, or cause it to collapse due to the internal pressure dropping to steam pressure. (Research on the Height Reduction Scheme of the Pressure-Standing Tower in Long-Distance Multi-Branch Water Supply Systems [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, effective measures are urgently needed to improve the safety and stability of the pipelines and reduce the risks of leakage and water hammer.

[0003] Researchers at home and abroad 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 their functions are relatively simple. However, the pressure fluctuations caused by the water hammer phenomenon impose 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 relevant test experiments that need to be solved urgently:

[0004] 1. Conducting experiments to locate leaks and investigate water hammer in long-distance, high-pressure water pipelines requires real-time monitoring and recording of changes in pressure and flow rates. Instruments used include pressure sensors, displacement sensors, flow meters, and data loggers. Low-precision equipment can lead to inaccurate experimental data, increasing the difficulty of the experiment.

[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 stage of experimental platform design, it is necessary to consider installing one-way valves and compensators to reduce the impact and damage of pressure fluctuations on water pumps and other related equipment. Summary of the Invention

[0007] The purpose of the present invention is to provide a water hammer and 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 small leaks occurring during high-pressure water transmission in existing testing and experimental technologies, as well as the problems of insufficient accuracy in collecting water hammer test signals and impact damage to equipment caused by water hammer tests.

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

[0009] The technical solution adopted by the present invention is a long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device, which includes a water tank, and also includes an outlet side experimental unit, a return water side main road experimental unit and a return water side branch experimental unit. The outlet side experimental unit and the return water side branch experimental unit are both connected to the return water side main road experimental unit, and the outlet side experimental unit, the return water side main road experimental unit and the return water side branch 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 connected in sequence through a pipeline. The second displacement sensor is connected to the return side main line experimental unit through a pipeline. The pipeline connecting the second displacement sensor and the return side main line experimental unit is 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 in sequence according to the direction of water flow.

[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 point, 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 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, specifically:

[0017] When conducting leakage monitoring and positioning experiments, close the second butterfly valve and electric ball valve, open the third butterfly valve and back pressure valve, and allow the return water to return to the water tank through the return water branch test unit. Then, open any leak point to monitor the change in 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, and allow the return water to return to the water tank through the return water main 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 operating procedures for the leakage monitoring experiment are 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 0.1 MPa 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 working condition, and then open any one or more leakage points, monitor the change of the 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 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 when no leakage experiment occurs under the same flow and pressure working conditions, leakage monitoring is achieved;

[0021] When determining the location of pipeline leaks, assume that the propagation speed of the negative pressure wave in the pipeline is a, P is the leak point, the upstream pressure sensor of the leak point P is A, the downstream pressure sensor of the leak point is B, and the distance between the upstream pressure sensor A of the leak point and the downstream pressure sensor B of the leak 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 leak 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 between the same negative pressure waveform caused by the leak and the time it takes to reach the two sensors. d Assuming the fluid velocity is ν and the distance between the upstream pressure sensor A and the calculated leak point P is X, we have:

[0022]

[0023] When a pipeline leaks, the relative error formula is used for calculation:

[0024]

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

[0026] Obtain the time delay value T through fast Fourier transform dThe specific method includes the following steps: (1) signal acquisition: upstream pressure sensor A and downstream pressure sensor B acquire signal data; (2) preprocessing: low-pass filtering is performed on the signal data acquired by upstream pressure sensor A and downstream pressure sensor B to remove high-frequency noise; (3) fast Fourier transform: fast Fourier transform (FFT) is performed on the signals x(n) and y(n) acquired by upstream pressure sensor A and downstream pressure sensor B, and x(n) and y(n) are converted from time domain to frequency domain respectively to obtain frequency domain signals X(k) and Y(k), where n represents the time domain index, which represents the sequence number of the time series; k represents the index in the frequency domain, which represents the sequence 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 cross-correlation function R is obtained by multiplying the frequency domain signal X(k) with the complex conjugate Y'(k) of the frequency domain signal Y(k) and then performing inverse FFT. 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 side 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 by the air compressor, and change the ball valve opening to 30°, 45°, 60°, and 90° within 1 second, thereby realizing the cut-off water hammer; monitor the changes in the pipeline pressure value by 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 periodic pressure oscillation 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 signals at multiple locations in the water pipeline and pressure signals at multiple upstream and downstream locations 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 converter cabinet to directly electromagnetically control the flow of the water pump. The advantages of this technology are convenient flow regulation, rapid response, and a wide adjustment range. At the same time, a centrifugal pump, back pressure valve, butterfly valve, ball valve and other devices are used to coordinately adjust experimental parameters such as flow and pressure. 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 for repeated verification of the research method. This provides 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 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 as needed and adjust and control the experimental conditions. Compared with experiments conducted in actual pipeline systems, the experimental platform is less expensive and easier to control and manage. This allows for more diverse data and results, 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; in actual engineering, high-pressure water is often transported. 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 pressure of the experimental working condition reaches a maximum of 1MPa. The pipeline diameter is DN100, the pipeline length reaches 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 diagram of the water hammer, leakage monitoring and positioning test device for long-distance high-pressure water pipelines of the present invention;

[0037] Figure 2 This is a diagram showing the principle of calculating the cross-correlation function using the Fast Fourier Transform (FFT);

[0038] Figure 3 This is a schematic diagram of the principle of locating water pipeline leaks;

[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 is 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 valve closing in the water pipeline. The pipeline inlet flow rate Q = 30m 3 / h;

[0044] Figure 9 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 flow rate of the pipeline inlet is 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. Seventh pressure sensor, 22. Fourth leakage point, 23. Eighth pressure sensor, 24. Third displacement sensor, 25. Ninth pressure sensor, 26. Fourth displacement sensor, 27. Fifth leakage point, 28. Tenth pressure sensor, 29. Eleventh pressure sensor, 30. Sixth leakage point, 31. Twelfth pressure sensor, 32. Second electromagnetic flowmeter, 33. Manual exhaust valve, 34. Second butterfly valve, 35. Electric ball valve, 36. One-way valve, 37. First compensator, 38. Third butterfly valve, 39. Back pressure valve, 40. Second compensator. DETAILED DESCRIPTION

[0046] The present invention will be 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 connected in sequence through a pipeline. The second displacement sensor 13 is connected to the return side main line experimental unit through a pipeline. The pipeline connecting the second displacement sensor 13 and the return side main line experimental unit is provided with a fifth pressure sensor 14, several third leakage points 15, a sixth pressure sensor 16, a first automatic exhaust valve 17, and a second automatic exhaust valve 18 in sequence according to the direction of water flow;

[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. 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 provided on the pipeline between the first displacement sensor 9 and the second displacement sensor 13 according to the direction of water flow.

[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; a ninth pressure sensor 25 is arranged on the pipeline between the third displacement sensor 24 and the fourth displacement sensor 26; 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 are arranged in sequence according to the direction of water flow on the pipeline between the fourth displacement sensor 26 and the second electromagnetic flowmeter 32; the pipeline between the manual exhaust valve 33 and the second butterfly valve 34 is connected to the return water side branch experimental unit.

[0052] The return 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 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, which 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, thereby changing the flow rate of the experimental device. The centrifugal pump 2 is connected to the ball valve 3 and the first butterfly valve 4 in sequence through the flange. 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 acquisition card. 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 life. The leakage point hole diameter is 13mm and is connected to the bottom of the pipeline with a thread. 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. 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, which are used 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 on the return side pipeline are connected on the pipeline with a flange, and the seventh pressure sensor 21 is connected further down the pipeline. Seven fourth leakage points 22 with a diameter of 13 mm are set between the seventh pressure sensor 21 and the eighth pressure sensor 23, and the interval is 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. The fourth displacement sensor 26 and seven fifth leakage points with a diameter of 13 mm are set between the ninth pressure sensor 25 and the tenth pressure sensor 28. The leakage points 27 are spaced 2 meters apart. 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, with an interval of 2 meters. The twelfth pressure sensor 31 is connected to a second electromagnetic flowmeter 32 to monitor the flow rate on the return water side. It can also be connected to an 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 back of the electromagnetic flowmeter. When there is gas in the pipeline, the exhaust valve is manually opened to discharge the air.

[0055] The manual exhaust valve 33 of the lower return water pipe is connected to the second butterfly valve 34 through a tee, 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 followed by a one-way valve 36. 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 followed by a first compensator 37 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 their impact and damage to the pipeline and related equipment. The compensator can also have a certain shock absorption capacity, thereby reducing noise and extending the service life of the pipeline equipment.

[0056] The manual exhaust valve 33 on 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 easier to monitor the leakage signal. The back pressure valve 39 is followed by a 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 a leakage monitoring and positioning test, close the second butterfly valve 34 and the electric ball valve 35, open the third butterfly valve 38 and the back pressure valve 39, and allow the return side water to return to the water tank 1 through the return side branch test unit. Then, open any leak point to monitor the change in the pipeline pressure value to achieve leakage monitoring and positioning.

[0058] When conducting 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, and allow the return water to return to the water tank 1 through the return water main line test unit. Then, change the opening of the electric ball valve 35 to monitor the change in the pipeline pressure value to implement a cut-off water hammer test; or close any leakage point to monitor the change in the pipeline pressure value to implement 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 working 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 no-leakage experiment under the same flow and pressure conditions, leakage detection is achieved;

[0060] The specific operation process 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 1 through the lower return pipe, close any leakage point (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 22, the fifth leakage point 27, and the sixth leakage point 30) to achieve 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 generating a cut-off water hammer; and use the first pressure sensor 6, the second pressure sensor 8, the third pressure sensor 10, and the fourth pressure sensor 11 to detect the leakage. 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 test is achieved.

[0061] The preparations before doing leakage monitoring experiments or water hammer experiments 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, and open the centrifugal pump 2 pipeline for water inlet. The frequency converter can change the power of the centrifugal pump 2 and thus change the pipeline flow. The flow changes are observed by the first electromagnetic flowmeter 5 and the second electromagnetic flowmeter 32, and leakage and water hammer experiments under different flow conditions can be realized. 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. 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; and 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 leak point, the upstream pressure sensor of the leak 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 leak point P be B, and the distance between the upstream pressure sensor A of the leak point P and the downstream pressure sensor B of the leak 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 leak 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 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 leak 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 leak point location, and X′ represents the actual leak point location.

[0068] To further verify the accuracy of pipeline leak location, the present invention uses the 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, accurately measuring the time difference or delay between two signals is very critical. Traditional delay estimation methods, such as direct correlation, may be limited by computational complexity and processing time. The Fast Fourier Transform (FFT) provides an effective way to significantly accelerate the delay estimation process while maintaining high accuracy.

[0069] Figure 2 This is the principle diagram of Fast Fourier Transform (FFT), as shown in 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 cross-correlation function R is obtained by multiplying the frequency domain signal X(k) with the complex conjugate Y'(k) of the frequency domain signal Y(k), and then performing an inverse FFT (IFFT). 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 the pipeline leakage is shown in the figure. The x-axis is the sample collected over time. It is set to collect 2000 samples per second. 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. However, 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%. When the volume flow rate Q = 30m 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. However, 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 time taken to calculate the leak point is 0.014861s. Substituting this into the formula, the leak point is calculated to be 1.918m. However, the actual leak hole X' is located 2m from the upstream pressure sensor A (i.e., pressure sensor 28). Therefore, the positioning error of the leak hole is 4.1%. It can be seen that the leakage monitoring accuracy of the present invention is high, and the accuracy increases with increasing flow rate.

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

[0072] Figures 7 to 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. The y-axis is the pressure size. 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. For example, 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 5-7 The pressure fluctuations shown by the valve closing are 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] Valve-closing water hammer experiments show that as flow increases, the amplitude of pressure oscillations within the pipeline also increases, but the period of pressure oscillation decreases. The water hammer wave then gradually decreases and dissipates, and the pipeline pressure returns to normal. There is no negative pressure during the entire process. Increasing flow improves operational safety, but when closing a valve in an emergency, higher flow can lead to greater pressure shocks and potential risks.

[0074] The device of the present invention can accurately locate pipeline leaks and perform water hammer experiments. 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 present invention discloses a device for monitoring and locating water hammer and leaks in long-distance (hundred-meter-class), large-diameter (DN100) high-pressure water pipelines. The main test unit is equipped with a back-pressure valve that can increase the pressure within the pipeline to 1 MPa. A check valve and compensator are also installed in the main test unit to reduce the impact and damage of pressure fluctuations on water pumps and other related equipment. This device can conduct high-pressure water pipeline leak location tests, as well as valve-off water hammer and flow-off water hammer tests. This solves the existing problem of difficulty in monitoring and locating small leaks during high-pressure water delivery, as well as the difficulty in accurately collecting pressure signals during water hammer tests and the impact and damage caused by water hammer tests to equipment. It facilitates analysis of the coupling relationship between water hammer and leaks.

[0076] By simulating fluid movement in a piping system, the device described in this paper can study and analyze the causes, characteristics, and impacts of water hammer. The experimental device can measure water hammer pressure and shock wave propagation velocity under different operating conditions, thereby assisting in engineering design and optimization of piping systems, mitigating water hammer damage to piping and equipment, and improving system stability and safety.

[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 connected in sequence through a pipeline. The second displacement sensor 13 is connected to the return side main line experimental unit through a pipeline. The pipeline connecting the second displacement sensor 13 and the return side main line experimental unit is provided with a fifth pressure sensor 14, several third leakage points 15, a sixth pressure sensor 16, a first automatic exhaust valve 17, and a second automatic exhaust valve 18 in sequence according to the direction of water flow;

[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. 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 provided on the pipeline between the first displacement sensor 9 and the second displacement sensor 13 according to the direction of water flow.

[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 connected in sequence through a pipeline. The second displacement sensor 13 is connected to the return side main line experimental unit through a pipeline. The pipeline connecting the second displacement sensor 13 and the return side main line experimental unit is provided with a fifth pressure sensor 14, several third leakage points 15, a sixth pressure sensor 16, a first automatic exhaust valve 17, and a second automatic exhaust valve 18 in sequence according to the direction of water flow;

[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. 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 provided on the pipeline between the first displacement sensor 9 and the second displacement sensor 13 according to the direction of water flow.

[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; a ninth pressure sensor 25 is arranged on the pipeline between the third displacement sensor 24 and the fourth displacement sensor 26; 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 are arranged in sequence according to the direction of water flow on the pipeline between the fourth displacement sensor 26 and the second electromagnetic flowmeter 32; the pipeline between the manual exhaust valve 33 and the second butterfly valve 34 is connected to the return water side branch experimental unit.

[0090] The return 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 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 conducting a leak monitoring and location test, close the second butterfly valve 34 and the electric ball valve 35, open the third butterfly valve 38 and the back pressure valve 39, and allow the return water to return to the water tank 1 through the return water branch experimental unit. Then, open any leak point to monitor the change in the pipeline pressure value to achieve leak monitoring and location.

[0093] When conducting 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, and allow the return water to return to the water tank 1 through the return water main line test unit. Then, change the opening of the electric ball valve 35 to monitor the change in the pipeline pressure value to achieve a cut-off water hammer test; or close any leakage point to monitor the change in 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 by: It includes a water tank (1), and also includes an outlet side experimental unit, a return water side main road experimental unit and a return water side branch experimental unit, the outlet side experimental unit and the return water side branch experimental unit are both connected to the return water side main road experimental unit, and the outlet side experimental unit, the return water side main road experimental unit and the return water side branch experimental unit are all connected to the water tank (1); 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) connected in sequence through a pipeline. The second displacement sensor (13) is connected to the return side main path experimental unit through 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 provided on the pipeline connecting the second displacement sensor (13) and the return side main path experimental unit according to the direction of water flow. 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 provided on the pipeline between the first displacement sensor (9) and the second displacement sensor (13) according to the direction of water flow; 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 one-way 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 provided 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 provided on the pipeline between the fourth displacement sensor (26) and the second electromagnetic flowmeter (32) in sequence according to the direction of water flow; the pipeline between the manual exhaust valve (33) and the second butterfly valve (34) is connected to the return water side branch experimental unit; The return water branch experimental unit 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 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).

2. The method for using the long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device according to claim 1 is 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 to allow the return side water to return to the water tank (1) through the return side branch experimental unit. Then, any leakage point is opened to monitor the change in 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 side water returns to the water tank (1) through the return side 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; 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 working condition, and then open any one or more leakage points, and use the first pressure sensor (6), the second pressure sensor (7) and the second pressure sensor (8) to detect the leakage. 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 no-leakage experiment under the same flow rate and pressure conditions, leakage detection is achieved; When determining the location of pipeline leakage, assume that the propagation speed of the negative pressure wave in the pipeline is , P is the leak point, the upstream pressure sensor of the leak point P is A, the downstream pressure sensor of the leak point is B, and the distance between the upstream pressure sensor A of the leak point and the downstream pressure sensor B of the leak 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 leak 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 between the same negative pressure waveform caused by the leak and the time it takes to reach the two sensors. d ; Assume the fluid velocity is , 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 for calculation: Where, Indicates the calculated leak point location, The actual leak point location.

3. The method for using the long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device according to claim 2 is characterized in that: Obtain the time delay value T through fast Fourier transform d The specific method includes the following steps: (1) signal acquisition: upstream pressure sensor A and downstream pressure sensor B acquire signal data; (2) preprocessing: low-pass filtering is performed on the signal data acquired by upstream pressure sensor A and downstream pressure sensor B to remove high-frequency noise; (3) fast Fourier transform: fast Fourier transform FFT is performed on the signals x(n) and y(n) acquired by upstream pressure sensor A and downstream pressure sensor B, and x(n) and y(n) are converted from time domain to 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 cross-correlation function R is obtained by multiplying the frequency domain signal X(k) with the complex conjugate Y'(k) of the frequency domain signal Y(k) and then performing inverse FFT. 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 .

4. The method for using the long-distance high-pressure water pipeline water hammer, leakage monitoring and positioning test device according to claim 2 is characterized in that: The specific operation process of the water hammer test is as follows: close the third butterfly valve (38) to allow the return side water to return to the water tank through the return side main line test unit, close any leakage point, and 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 realizing the cut-off water hammer; The force 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), the first displacement sensor (9), the second displacement sensor (13), the third displacement sensor (24), and the fourth displacement sensor (26) monitor the change in 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, a continuous sinusoidal wave signal appears, and the pressure wave undergoes an attenuation process, thereby realizing a water hammer experiment.

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