Experimental device and method for exciting noise characteristics by impacting different materials with high-speed water flow

Abstract

The invention discloses a high-speed water flow impact different material excitation noise characteristic experiment device, which comprises a closed experiment box, which is composed of a sound insulation rubber plate and sound absorption cotton and is used for isolating external noise interference; the water flow circulating system comprises a water tank, a variable-frequency and variable-speed water pump, an intelligent flow regulating valve, a high-pressure spray head and a Doppler current meter and is used for controlling and regulating the flow speed and flow of high-speed water flow; the material fixing device is of a groove structure and is used for fixing different material test pieces and ensuring that the centers of the test pieces are aligned with the impact center of the high-pressure spray head; and the acoustic measurement system comprises a high-sensitivity hydrophone, a noise signal acquisition card and computer software, and is used for acquiring and analyzing noise signals excited by the water flow impacting the test piece. By analyzing and monitoring the characteristics of noise excited by high-speed water flow impacting different material wall surfaces, the relation between physical characteristics of materials and noise is established, and a scientific basis is provided for water turbine foreign matter entering fault diagnosis.

Description

Technical Field

[0001] The present invention relates to the field of noise generated by high-speed water flow impacting materials and material physical properties, and particularly to an experimental device and method for studying the noise characteristics excited by high-speed water flow impacting different materials. Background Art

[0002] Tree branches, stones from trash racks and fixed components that fall off due to deteriorated hydraulic conditions will flow into the water turbine runner. This may cause damage to the main components of the water turbine. However, due to the deep burial and closed characteristics of the water turbine runner, it is difficult to capture the abnormal water flow noise characteristics excited by foreign objects of different materials, and it is impossible to determine the type of foreign object material entering the water turbine, ultimately affecting the normal operation of the hydropower station. At the same time, when there are sundries on the water passage components of the water turbine, it will cause the water turbine to make noise and abnormal sounds during operation. Therefore, carrying out research on the noise characteristics excited by high-speed water flow impacting different materials provides reference data for the faults caused by foreign objects of different materials entering the water turbine, so as to maintain the economic benefits of the hydropower station and ensure the safe operation of the hydropower station.

[0003] When water flows through the water turbine and discharges, during the process of collision and energy transfer with the flow components of its own structure and foreign objects invading from outside, it will generate high-decibel discharge noise. However, the noise signals excited by different materials impacted by water flow are different. Through the analysis and research on the noise characteristics excited by water flow impacting different materials, the purpose of identifying foreign object materials in the water turbine runner can be achieved. At the same time, using noise monitoring as a new monitoring means to improve the traditional vibration monitoring means has certain value for the water turbine fault monitoring means.

[0004] However, at present, there is little research on the noise characteristics excited by water flow in the water turbine impacting different materials. Chang Jinqiu et al. measured the sound pressure levels of the water passing noise of ordinary UPVC drain pipes and traditional cast iron pipes respectively, and verified that the noises excited when water flows through different materials are different. However, this experiment used different material drain pipes for the experiment, and the obtained noise is the noise of water flowing through the drain pipe, which has a large difference from the way water flow impacts materials inside the water turbine. Huang Wenjing et al. studied the sound characteristics when pouring water through software. They used porcelain cups, plastic cups, thermos cups and glass cups for experiments respectively and listed the spectrum display diagrams for comparison and found that the loudness and main frequency of the spectrum diagrams of different materials are different. However, no further analysis was carried out, and it is difficult to distinguish different materials only by comparing the spectrum display diagrams of noise in the water turbine runner. Therefore, the research on the noise excited by water flow impacting different materials in the water turbine runner is not deep enough.

[0005] At the same time, the existing research methods also have certain limitations: it is difficult to accurately control the water flow conditions in the water turbine runner, the measurement and analysis of noise are not comprehensive enough, the information contained in the noise cannot be fully extracted, and the characteristics of different materials are not considered enough, and there is no established connection between the physical characteristics of the material itself and the excited noise characteristics.

[0006] Therefore, an experimental device and method for exciting noise characteristics by high-speed water flow impacting different materials are proposed to solve the above problems. Summary of the Invention

[0007] The purpose of the present invention is to overcome the above deficiencies, provide an experimental device and method for exciting noise characteristics by high-speed water flow impacting different materials, and solve the problems in the background technology.

[0008] In view of the above problems, the technical solution adopted by the present invention is: an experimental device for exciting noise characteristics by high-speed water flow impacting different materials, including: A sealed experimental chamber, composed of sound-insulating rubber sheets and sound-absorbing cotton, is used to isolate external noise interference; A water flow circulation system, including a water tank, a variable-frequency speed-regulating water pump, an intelligent flow regulating valve, a high-pressure nozzle, and a Doppler flow velocity meter, is used to control and regulate the flow velocity and flow rate of the high-speed water flow; A material fixing device, formed by welding Q460 steel plates into a groove structure, is used to fix different material specimens and ensure that the center of the specimen is aligned with the impact center of the high-pressure nozzle; An acoustic measurement system, including a high-sensitivity hydrophone, a noise signal acquisition card, and computer software, is used to collect and analyze the noise signals excited by the water flow impacting the specimen.

[0009] Preferably, the sealed experimental chamber is a cuboid structure with a length of 160 cm × a width of 90 cm × a height of 60 cm, and is wrapped with sound-absorbing cotton with a length of 164 cm × a width of 94 cm × a height of 62 cm, and the thickness of the sound-absorbing cotton is 2 cm.

[0010] Preferably, both the water storage tank and the return water tank of the water flow circulation system are made of Q460 steel. The size of the water storage tank is 100 cm in length × 80 cm in width × 40 cm in height, and the return water tank is a cube with a side length of 30 cm; the inlet diameter of the high-pressure nozzle is 10 cm, and the outlet diameter is 3 cm.

[0011] Preferably, the material fixing device includes four load-bearing columns with a length of 10 cm × a width of 10 cm × a height of 43.1 cm, welded above the return water tank, and the groove size is 10 cm in length × 10 cm in width × 3 cm in height, and is used to fix a cube specimen with a side length of 10 cm.

[0012] Preferably, the hydrophones of the acoustic measurement system are arranged at three measuring points CH1, CH2, and CH3 around the specimen. The distance between the hydrophone and the specimen surface is 6 cm, and is connected to the noise signal acquisition card through an optical fiber jumper.

[0013] Preferably, the joints of the sealed experimental chamber are filled with sealant, wrapped with sound-absorbing cotton on the outer layer, and fixed with waterproof adhesive tape.

[0014] Preferably, a Doppler flow velocity meter is installed between the intelligent flow regulating valve and the high-pressure nozzle for real-time monitoring of the water flow velocity.

[0015] Preferably, an adjustable cylinder is provided below the material fixing device for adjusting the specimen impact angle to 0° or 90°.

[0016] In addition, the present invention also discloses an experimental method for an experimental device for studying the noise characteristics excited by high-speed water flow impacting different materials, including the following steps: Step 1: Fix the standardized specimen in the groove of the material fixing device and seal the experimental chamber; Step 2: Adjust the water pump speed and the opening degree of the intelligent flow regulating valve to stabilize the water flow velocity to the set value; Step 3: Turn on the acoustic measurement system, collect the noise signal around the specimen, and extract the sound pressure level, main frequency, and frequency band width parameters through spectral analysis and time-frequency analysis; Step 4: Replace the specimen and repeat the experiment, and establish a correlation model between the noise characteristics and the material parameters in combination with the physical characteristics of the material.

[0017] Furthermore, the water flow velocity is set to 0 - 27 m / s, and the impact angle is adjusted to 0° or 90°.

[0018] The present invention has the following beneficial effects: 1. By constructing a highly simulated water flow circulation system, the present invention ensures the accurate control and stable adjustment of water flow parameters such as flow velocity and impact angle, provides reliable experimental conditions for studying the noise characteristics excited by water flow impacting different materials, greatly improves the accuracy and repeatability of experimental results, provides a large amount of collision noise data for the actual operation state monitoring and fault diagnosis of hydraulic turbines, and forms a noise database of water flow impacting different materials; 2. Through multiple highly sensitive hydrophones at different positions, the present invention can horizontally compare the differences in noise signal data measured at different measurement positions, comprehensively and accurately collect the noise signals generated by water flow impacting the specimen, and reveal the energy distribution in the noise signals through the characteristic parameters in spectral analysis and time-frequency analysis, providing a basis for in-depth discovery of the mechanism of water flow and material collision; 3. The present invention standardizes various representative materials in the flow channels of various hydraulic turbines and conducts various physical property tests, establishes the relationship between the material itself characteristics and the excited noise characteristics, provides a scientific basis for the selection, transformation of future hydraulic turbines and the identification of foreign material in the flow channel, and improves the safety and reliability of hydraulic turbines from the aspect of material characteristics; 4. The present invention analyzes in detail the influence of water flow parameters and different measuring points on the noise characteristics, summarizes the laws between water flow parameters and noise characteristics, and provides theoretical guidance for the actual operation process of the water turbine during the optimization process through these laws. It helps the staff to detect and prevent abnormal situations in the operation of the water turbine in a timely manner by monitoring the noise signal, effectively reducing the operation and maintenance costs of the water turbine, improving the economic benefits of the hydropower station and ensuring its safe operation; 5. The present invention introduces noise monitoring as a new monitoring means into the field of water turbine fault detection, makes up for the deficiencies of traditional vibration monitoring means, provides new ideas and methods for the development of water turbine fault monitoring technology, and the successful implementation of this experimental method is conducive to promoting the innovation and development of water turbine monitoring technology. Brief Description of the Drawings

[0019] Figure 1 is a perspective view of the device of the present invention; Figure 2 is a perspective sectional view of the device of the present invention; Figure 3 is a schematic diagram of the measuring point layout of the acoustic measurement system in the present invention; Figure 4 is a schematic diagram of the connection between the water pump and the water pipe in the present invention; Figure 5 is a schematic diagram of the water flow circulation system in the present invention; Figure 6 is a schematic diagram of the material fixing device in the present invention. Detailed Embodiment

[0020] The present invention will be further described below with reference to the drawings and embodiments: [[ID=BO]]Refer to Figures 1 to 6 As shown, in this specific embodiment, an experimental device and method for exciting noise characteristics by high-speed water flow impacting different materials are provided, including a closed experimental environment, a water flow circulation system, a material fixing device, and an acoustic measurement system.

[0021] To simulate a closed experimental environment, the entire experimental device uses soundproof rubber plates to form a closed experimental box, as shown in the appendix Figure 1As shown in Figure 1; to ensure the complete fitting of the joints between materials, sealant is used to fill the gaps at the joints 8 to prevent external water and sound from entering the interior of the device. The outer surface of the closed experimental chamber is tightly wrapped with sound-absorbing cotton, cut into the required size according to the shape and size of the device to ensure that the sound-absorbing material perfectly wraps the entire experimental device, and then the sound-absorbing material is fixed with waterproof tape. The external noise is further absorbed by the sound-absorbing material to reduce the interference with the experimental measurement. And the same measures are taken for the side of the acoustic measurement, that is, the side of the device that receives the acoustic signal. This part is isolated by the sound-insulating rubber plate 15 to further isolate the sound-insulating effect and ensure the accuracy of the acoustic measurement system in collecting the noise signals excited by the water flow impacting different specimens.

[0022] The water circulation system includes: placing the water tank 6 on a horizontal and solid ground to ensure that it is stable and has sufficient load-bearing capacity. At the same time, use bolts, increase the load-bearing capacity of the water tank, and use iron fences to fix the water tank on the ground to prevent the water tank from shifting or shaking during the experiment. Check whether the inside of the water tank is clean. If there is any debris or residue, it needs to be cleaned up. Then start injecting enough experimental water into the water tank to ensure that the water flow rate ejected by the high-pressure nozzle 14 can meet the experimental requirements. Place the variable frequency speed regulation water pump 7 in the water tank 6 to ensure that the injected experimental water submerges the water pump 7. At the same time, connect the water outlet of the water pump 7 to the water outlet of the high-pressure nozzle 14 through the sealing water pipe 9. Use sealing gaskets at the connection to ensure the sealing of the connection and prevent water leakage. Connect the power cord of the water pump 7 and connect it to the control system to ensure that the water flow rate can be accurately adjusted according to the experimental requirements during the experiment. An intelligent flow control valve 2 is installed between the water pump 7 and the high-pressure nozzle 14, near the nozzle. A power cord connects the intelligent flow control valve 2 to a control panel, ensuring that the control panel is located outside the entire sealed experimental apparatus. This facilitates operation and adjustment, providing real-time feedback on water flow parameters and automatically adjusting the flow rate according to pre-set parameters required for the experiment. The intelligent flow control valve 2 is tightly connected to the water pipe 9, and a sealing gasket is also used at the joint to ensure a tight seal. The intelligent flow control valve 2 and the high-pressure nozzle 14 are connected via a water pipe. A Doppler velocity meter (ADV) is installed at the designated measurement location between the high-pressure water gun and the intelligent flow control valve, ensuring that the measured flow velocity is consistent with the high-pressure nozzle jet velocity. The high-pressure nozzle 14 is mounted at the end of the water pipe, ensuring that its installation orientation accurately directs the water flow to the center of the test specimen 4 on the material fixture, simulating the water jet in the turbine flow channel. This ensures that the water flow strikes the different materials at a consistent angle and provides sufficient water impact force. After the water flow impacts the test piece, to prevent the water flow from splashing onto the surrounding walls or stagnating on the material fixture, a non-absorbent material 5 is used to surround the material fixture, reflecting the water flow while fixing the acquisition device of a certain measurement point of the acoustic measuring instrument 3, so that the water flow flows into the water tank 12 below the material fixture and then flows back to the water tank 6 through the water pipe 9. After completing the above operations, the water circulation system is checked for leaks or whether repairs are needed. The water pump 7 is turned on and the speed of the water pump 7 and the valve opening of the intelligent flow control valve 2 are slowly adjusted to ensure that the water flow in the water pipe 9 is stable and leak-free. At the same time, the values on the control panels of the water pump 7, the flow meter, and the intelligent flow control valve 2 are observed to see if they can reach the predetermined experimental values. If any leaks occur during the entire test process, the water pump 7 should be turned off and repaired in a timely manner to ensure the smooth progress of the subsequent experimental process.

[0023] The material fixing device includes: Fixing the fixing device above the water tank 12 by means of welding. Connect it to the flat cylindrical steel plate 16 supporting the specimen through four firm and thick enough steel plates. Ensure that all the welded joints of the steel plate 16 are full welds to avoid fracture caused by the excessive weight of the specimen during the experiment and ensure the firm stability of the fixing device. Ensure that the center point of the material specimen 4 is directly opposite the position where the water flow impacts, ensuring the accuracy of the water jet hitting the center of the specimen 4. Surround the specimen with a stainless steel plate 13 around the specimen. Use full welds to weld the flat cylindrical steel plate 16 and the stainless steel plate 13 to form a groove that can just place the specimen, ensuring that there will be no displacement, shaking or even falling off due to the water flow impact during the experiment. When replacing the specimen 4, directly take out the specimen 4 at the corresponding position and place it back into the groove. The entire material fixing device is supported by four load-bearing columns 11 placed on the horizontal ground below. Place a cylinder 10 with a height half of the height of the specimen between the load-bearing column 11 and the material fixing device as an adjustable component for controlling the position of the impact specimen and adjusting the impact specimen angle to 0° or 90°. To ensure that it can bear the weight of the entire acoustic measurement device and the material fixing device, the material selected for the cylinder component 10 is steel with relatively strong compressive capacity.

[0024] The acoustic measurement system includes: Place three high-sensitivity hydrophones 3 at three different angular observation point positions around the specimen 4, namely CH1, CH2, and CH3, and use a special mounting bracket or a firm and clampable fixture supporting the hydrophone to fix the hydrophone at the corresponding position of the observation point. Place the hydrophone 3 at a certain distance from the specimen 4 to ensure that during the experiment, the water flow will not directly impact the hydrophone 3 and cause it to be damaged, while being able to clearly collect the noise signals of the water flow impacting different material specimens as much as possible. Enable the position of the hydrophone relative to the specimen to be adjusted to ensure that the hydrophone 3 can accurately collect the noise signals from different directions of the specimen 4. Connect the hydrophone 3 to the supporting noise signal acquisition card through an optical fiber jumper. Install the data acquisition software supporting the data acquisition card on the computer, and after connection, conduct a test to ensure that during the experiment, the software on the computer can timely and accurately collect the signals collected by the hydrophone 3 and convert them into storable signals for convenient subsequent processing. After completing the above steps, use the CAL standard sound source of the American PCB company to calibrate the capacitive acoustic sensor. By adjusting the Hz of the calibration device, after turning on the switch, connect the hydrophone 3 to the standard sound source, and compare the Hz value of the standard sound source with the parameters displayed in real time on the computer to adjust and calibrate the sensitivity and accuracy of the hydrophone 3 to ensure the accuracy of the acoustic measurement system and improve the reliability of the measured value.

[0025] After completing the installation of the above system, start the water flow circulation system. Pump the water in the water tank 6 through the variable frequency speed control water pump 7 to make the water flow stably in the water pipe 9, ensuring the stability and cyclic flow of the water in the entire water flow circulation system. Then adjust the flow control valve 2 and the water pump 7 to make the flow rate of the water reach the precise set value, and turn on the high-pressure nozzle 14 to impact the material. Keep it running stably for 3 minutes. After ensuring that the water flow state is fully stable, install the first concrete material specimen 4 on the material fixing device and fix it with the corresponding tools equipped for the corresponding material, ensuring that the specimen is firmly fixed and the installation position of the specimen is accurate, and the included angle with the water flow direction meets the requirements of the experiment. Turn on the acoustic measurement system, open the signal acquisition software in the computer, and start to collect the noise signals generated by the water flow impacting the concrete specimen in real time. During the collection process, ensure that the collection time of each specimen experiment process is the same, and continuously monitor the flow rate of the water flow to ensure that its value is always floating within the allowable error range of the set value. At the same time, pay attention to the real-time change of the noise signal on the computer, and check whether there is an abnormal amplitude mutation or interference in the noise signal through the real-time monitoring interface. If an abnormality occurs, stop the experiment immediately. After completing the collection of the noise signals of the concrete specimens, turn off the acoustic measurement system, take out the specimens and replace them with metal specimens, and repeat the above installation and collection steps. Conduct experiments on all selected specimens, such as concrete, metal, rubber, etc. in turn. After completing the experiments on all material specimens under a set of specific water flow parameters, such as a flow rate of 27 m / s and an impact angle of 0°, change the flow rate / impact angle of the water flow. Adjust the water flow rate to 4.3 m / s or 3.43 m / s, and adjust the impact angle to 0° or 90°. Repeat the above entire experimental process again to measure the noise signals generated by different material specimens under different water flow parameters and different measuring points when impacted by the water flow; after completing the entire process, turn off the water flow circulation system and the acoustic measurement system, disconnect the power supply of the relevant equipment, and clean the experimental equipment to prevent impurities from being carried by the water flow during the next experiment, including draining the water in the water tanks 6 and 12, avoiding the water flow containing rust due to the long-term immersion of the water pump 7, cleaning the water stains on the material fixing device and the residues caused by the specimen damage due to the jet impact, and checking whether the experimental equipment is damaged. If damage occurs, repair it in time. If there is no damage, it needs to be maintained. Preprocess the collected signals, use the filtering algorithm to remove the interference components in the noise signals, that is, high frequency and low frequency, and adopt the noise reduction technology to reduce the influence of the background noise and improve the quality and analyzability of the collected noise signals. Use the signal analysis methods of spectrum analysis and time-frequency analysis to perform fast Fourier transform and wavelet transform on the preprocessed noise signals, extract the characteristic parameters of the noise, such as sound pressure level, main frequency, frequency band width, etc., and analyze the energy distribution of the noise signals excited by the water flow impacting different materials through the characteristic parameters. After analyzing the energy distribution, combine the basic parameters of the materials to discover the relationship between the physical properties of different materials and the energy distribution of the noise by establishing a mathematical model, such as the relationship between the elastic modulus and density of the material and the main frequency and sound pressure level.Analyze in detail the conditions of changing water flow parameters, such as water flow, impact angle, etc., or compare the influence of different measuring points CH1, CH2, CH3 on the characteristics of the noise signal, summarize the relationship between the water flow parameters and the noise characteristics, and provide feasible theoretical guidance for the actual operation and optimization process of the water turbine.

[0026] The above embodiments are only the preferred technical solutions of the present invention and should not be regarded as limitations on the present invention. The protection scope of the present invention should be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, the equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. An experimental device for exciting noise characteristics by high-speed water flow impacting different materials, characterized in that, Including: A sealed experimental chamber (1), composed of sound-insulating rubber sheets and sound-absorbing cotton, for isolating external noise interference; a water flow circulation system (2), including a water tank (6), a variable-frequency speed-regulating water pump (7), an intelligent flow regulating valve (3), a high-pressure nozzle (14), and a Doppler flow velocity meter, for controlling and regulating the flow velocity and flow rate of high-speed water; a material fixing device (4), which is a groove structure for fixing different material specimens and ensuring that the center of the specimen is aligned with the impact center of the high-pressure nozzle; an acoustic measurement system (5), including a high-sensitivity hydrophone (3), a noise signal acquisition card, and computer software, for collecting and analyzing the noise signals excited by the water flow impacting the specimen.

2. The experimental device for exciting noise characteristics by high-speed water flow impacting different materials according to claim 1, wherein: The sealed experimental chamber (1) is a cuboid structure with a length of 160 cm × a width of 90 cm × a height of 60 cm, and is wrapped with sound-absorbing cotton with a length of 164 cm × a width of 94 cm × a height of 62 cm, and the thickness of the sound-absorbing cotton is 2 cm.

3. An experimental device for exciting noise characteristics by high-speed water flow impacting different materials according to claim 1, characterized in that: Both the water storage tank and the water return tank of the water flow circulation system (2) are made of Q460 steel. The size of the water storage tank is 100 cm in length × 80 cm in width × 40 cm in height, and the water return tank is a cube with a side length of 30 cm; the inlet diameter of the high-pressure nozzle (14) is 10 cm, and the outlet diameter is 3 cm.

4. An experimental device for exciting noise characteristics by high-speed water flow impacting different materials according to claim 1, characterized in that: The material fixing device (4) includes four load-bearing columns (11) with a length of 10 cm × a width of 10 cm × a height of 43.1 cm, welded above the water return tank, and the groove size is 10 cm in length × 10 cm in width × 3 cm in height, for fixing a cube specimen with a side length of 10 cm.

5. An experimental device for exciting noise characteristics by high-speed water flow impacting different materials according to claim 1, characterized in that: The hydrophone (3) of the acoustic measurement system (5) is arranged at three measuring points CH1, CH2, and CH3 around the specimen. The distance between the hydrophone and the specimen surface is 6 cm, and it is connected to the noise signal acquisition card through an optical fiber jumper.

6. An experimental device for exciting noise characteristics by high-speed water flow impacting different materials according to claim 1, characterized in that: The joints of the sealed experimental chamber (1) are filled with sealant, and the outer layer is wrapped with sound-absorbing cotton and fixed with waterproof tape.

7. An experimental device for exciting noise characteristics by high-speed water flow impacting different materials according to claim 3, characterized in that: A Doppler flow velocity meter is installed between the intelligent flow regulating valve (3) and the high-pressure nozzle (14) for real-time monitoring of the water flow velocity.

8. An experimental device for exciting noise characteristics of different materials by high-speed water flow impact according to claim 1, characterized in that: An adjustable cylinder (10) is arranged below the material fixing device (4) for adjusting the impact angle of the specimen to 0° or 90°.

9. The experimental method of an experimental device for exciting noise characteristics by high-speed water flow impacting different materials according to any one of claims 1-8, characterized in that, Including the following steps: Step 1: Fix the standardized specimen in the groove of the material fixing device (4) and seal the experimental chamber; Step 2: Adjust the rotation speed of the water pump (7) and the opening degree of the intelligent flow regulating valve (3) to make the water flow velocity stable at the set value; Step 3: Turn on the acoustic measurement system (5), collect the noise signals around the specimen, and extract the sound pressure level, main frequency, and frequency band width parameters through spectrum analysis and time-frequency analysis; Step 4: Replace the specimen and repeat the experiment, and establish a correlation model between the noise characteristics and material parameters in combination with the physical properties of the material.

10. The experimental method of an experimental device for exciting noise characteristics by high-speed water flow impacting different materials according to claim 9, characterized in that: The water flow velocity is set to 0 - 27 m / s, and the impact angle is adjusted to 0° or 90°.

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