A device and method suitable for automatic measurement of open channel flow velocity in a narrow space

Abstract

The application discloses a device and method suitable for open channel flow velocity automatic measurement in narrow space, the device comprises a support beam arranged and fixed above the open channel to be measured, a tension meter, a motor and an ultrasonic range finder are fixed at the bottom of the support beam, the tension meter is connected with a small ball by a fine rope with fixed length, the motor output end is connected with the small ball by a rope, the density of the small ball is less than water, the tension meter monitors the tension of the fine rope in real time; the ultrasonic range finder measures the vertical height from the initial position of the small ball to the water surface, the initial position, the upper end connecting point of the fine rope and the upper end connecting point of the rope are in the same height; the motor winds and unwinds the small ball in the form of winding the rope; the method comprises the following steps: the motor is started, the small ball is vertically lowered at a constant speed; at the moment when the small ball contacts the water surface, the motor is accelerated to completely release the rope; the tension meter monitors the moment of tension mutation; the average flow velocity of the open channel surface is calculated according to the obtained data. The application is suitable for flow velocity measurement in limited space, especially low flow velocity measurement.

Description

Technical Field

[0001] This invention relates to an automated fluid velocity measurement device and method, specifically to an automated fluid velocity measurement device and method suitable for open channels in confined spaces. Background Technology

[0002] Traditional automated methods for measuring flow velocity in open channels include the velocimeter method, the ultrasonic time-of-flight method, and the ultrasonic Doppler method. However, these methods have many shortcomings when applied to flow velocity measurement in confined spaces (such as seepage channels in power plants, small open channels in irrigation areas, urban drainage networks, and industrial wastewater discharge outlets).

[0003] (1) Current meters mainly include propeller current meters and electromagnetic current meters. Propeller current meters calculate flow velocity by measuring the rotational speed of the propeller driven by the water flow. The disadvantages are: first, the propeller has a significant interference with the flow field, especially in low-speed water flow, where the starting flow velocity is high, limiting the measurement accuracy; second, the propeller is easily entangled by weeds, garbage, etc., leading to measurement failure or damage; third, its measurement result is a point velocity, which requires multi-point measurement and integration calculation to obtain the cross-sectional average velocity, making the operation cumbersome and the degree of automation low. Electromagnetic current meters are based on Faraday's law of electromagnetic induction and calculate flow velocity by measuring the induced electromotive force generated by the water flow cutting magnetic field lines. The disadvantages are: the probe size is large, making it difficult to install in narrow channels, and the requirements for the boundary conditions of the flow field are high, and the conductivity of the channel wall will affect the measurement results.

[0004] (2) The ultrasonic time-difference method involves installing pairs of ultrasonic transducers on both banks of the channel and measuring the time difference of ultrasonic waves propagating in the downstream and upstream directions. This time difference is proportional to the water flow velocity, thereby calculating the flow velocity. The disadvantages are: First, the installation requirements are high, requiring precise alignment of the ultrasonic transducers, and the channel width cannot be too large or too small. For narrow channels with irregular shapes, the sound wave path is complex and easily affected by boundary reflections, leading to measurement failure. Second, it measures the line average velocity along the sound wave path, rather than the point velocity or cross-sectional average velocity, requiring velocity distribution correction. Third, the equipment cost is high, and the timing accuracy requirements of the electronic circuit are extremely high.

[0005] (3) Ultrasonic Doppler (ADCP) method calculates water flow velocity by emitting ultrasonic waves into the water and receiving the signals reflected back by suspended particles in the water, using the Doppler frequency shift effect. The disadvantages are: first, ultrasonic waves are also susceptible to interference from boundary reflections; second, ultrasonic equipment is expensive and complex to operate, and usually needs to be carried on ships or cableways for mobile measurements, making it unsuitable for long-term fixed-point monitoring in narrow channels; third, its measurement accuracy is affected by factors such as water quality, air bubbles, and suspended solids concentration. Summary of the Invention

[0006] Objectives of the invention: The first objective of this invention is to provide a device that is low in cost, high in accuracy, high in reliability, and highly adaptable for the automated measurement of flow velocity in open channels in confined spaces; the second objective of this invention is to provide a method for the automated measurement of flow velocity in open channels in confined spaces.

[0007] Technical Solution: This invention provides a device for automated flow velocity measurement in open channels within confined spaces. The device includes a support beam, a small ball, a data processing unit, a rope, and a low-elasticity thin rope. The support beam spans and is fixed above the open channel to be measured. A tension gauge, a motor, and an ultrasonic rangefinder are fixed to the bottom of the support beam. The motor is positioned along the length of the support beam, with its output end facing the tension gauge. The length of the thin rope is... A tension gauge is connected to the upper end of a thin rope, and a small ball is connected to the lower end; the density of the small ball is less than that of water; the tension gauge is used to monitor the tension on the thin rope in real time and feed it back to the data processing unit; the upper end of a rope is connected to the output end of a motor, and the lower end is connected to the small ball; the rope is longer than the thin rope; the connection point at the upper end of the thin rope is at the same height as the connection point at the upper end of the rope; an ultrasonic rangefinder is used to measure the vertical height of the initial position of the small ball from the water surface. The data is fed back to the data processing unit. The initial position is at the same height as the connection point at the upper end of the thin rope. The data processing unit is used to control the motor to wind and release the ball in a winding manner, and to process the data to obtain the flow rate data.

[0008] Furthermore, the two ends of the supporting beam are fixed to the two side walls of the open channel to be tested.

[0009] Furthermore, the motor can be a stepper motor or a servo motor.

[0010] The present invention provides a method for automated measurement of flow velocity in open channels in confined spaces, employing the aforementioned device for automated measurement of flow velocity in open channels in confined spaces, comprising the following steps:

[0011] S1: Obtain the current vertical height from the initial position of the ball to the water surface using an ultrasonic rangefinder. ;

[0012] S2: In At that moment, the motor starts, propelling the ball at a constant speed. Drop vertically;

[0013] S3: Based on vertical height and speed Determine the moment when the ball touches the water surface At any moment The motor accelerates to fully release the rope; the moment of the sudden change in tension monitored by the dynamometer is obtained. Then based on the length Vertical height ,time and time The average flow velocity at the surface of the open channel was calculated. This completes one cycle of flow rate measurement;

[0014] S4: The motor reverses, resetting the ball to its initial position, preparing for the next flow rate measurement.

[0015] Furthermore, at any time = ,in Let be the radius of the small ball;

[0016] The distance the ball moves horizontally under the influence of the water flow for: ;

[0017] Average flow velocity at the surface of open channel The calculation formula is:

[0018] .

[0019] Furthermore, the data processing unit includes a memory and a processor. The memory stores a computer program, which, when executed by the processor, implements the steps of the method for automated measurement of flow velocity in open channels in confined spaces, thereby obtaining the average flow velocity on the surface of the open channel. .

[0020] Furthermore, the data processing unit also includes a communication module, which is used to send monitoring data and flow rate data to a remote monitoring center.

[0021] Furthermore, the processor is a microprocessor or a single-chip microcomputer.

[0022] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0023] (1) Extremely low flow field interference: The projected area and volume of the ball and string in the water are very small. Compared with traditional flow meters, the disturbance of the water flow caused by this device can be ignored. This makes the measurement results more realistically reflect the natural state of the water flow and avoids flow field distortion caused by the measuring equipment itself, thus ensuring high accuracy and high reliability of the measurement data.

[0024] (2) Wide adaptability and high reliability: The measurement principle of this invention is based on simple mechanical and geometric relationships and does not depend on the physicochemical properties of water (such as conductivity, sediment content, temperature, etc.), thus making it applicable to a wide range of situations. This device can effectively measure various types of water, including clear rivers, irrigation water with high sediment content, and industrial wastewater containing small amounts of oil or impurities. In particular, this invention excels at measuring low flow velocities that are difficult to measure using traditional methods.

[0025] This invention has a simple and compact structure, low installation space requirements, is suitable for space-constrained scenarios, has no complex and easily damaged mechanical parts, and can operate stably for a long time in harsh outdoor environments.

[0026] (3) The present invention has relatively low cost, is easy to maintain, and is easy to promote and apply. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a device structure for automated flow velocity measurement in open channels in confined spaces, provided by an embodiment of the present invention.

[0028] Figure 2 The length of the thin rope in the embodiment of the present invention Vertical height Distance of the ball A diagram showing the trigonometric function relationships between them;

[0029] Figure 3 This is a graph showing the change of the force gauge reading over time in an embodiment of the present invention. Detailed Implementation

[0030] The invention will now be further described with reference to the accompanying drawings.

[0031] Appendix Figures 1 to 3 The accompanying figure labels are as follows:

[0032] 1. Support beam; 2. Force gauge; 3. Thin rope; 4. Small ball; 5. Motor; 6. Ultrasonic rangefinder; 7. Data processing unit; 8. Rope.

[0033] Example 1: As Figure 1 As shown, Embodiment 1 provides a device for automated measurement of flow velocity in open channels in confined spaces, including a support beam 1, a tension gauge 2, a thin rope 3, a small ball 4, a motor 5, an ultrasonic rangefinder 6, a data processing unit 7, and a rope 8.

[0034] The supporting beam 1 is spanned and fixed above the open channel to be tested. The fixing method is not limited and can be determined as needed; for example, both ends of the supporting beam 1 can be fixed to the side walls of the open channel. The supporting beam 1 is made of a material with sufficient strength and corrosion resistance, such as stainless steel or aluminum alloy.

[0035] The tension gauge 2 is fixed at the bottom center of the supporting beam 1. The upper end of the thin rope 3 is connected to the tension gauge 2, and the lower end is connected to the small ball 4. The length of the thin rope 3 is... It uses high-strength, low-elasticity, water-resistant, and corrosion-resistant materials, such as steel wire rope and Kevlar rope, to ensure that the length of the thin rope 3 remains constant during measurement and remains stable during long-term use. The small ball 4 has a density less than water and can float on the water surface. The tension gauge 2 is used to monitor the magnitude of the tension on the thin rope 3 in real time and feed it back to the data processing unit 7. The length of the thin rope 3 It is one of the key parameters for calculating flow rate and needs to be accurately measured and calibrated before installation.

[0036] Motor 5 is installed at the bottom center of the support beam 1 along its length. The output end of motor 5 faces the tension gauge 2. A rope 8 is wound around the output end of motor 5. The upper end of rope 8 is connected to the motor output end, and the lower end is connected to a small ball 4. Furthermore, the upper connection point of the thin rope 3 is at the same height as the upper connection point of rope 8. Rope 8 is slightly longer than thin rope 3, for example, 1.25m. This is to ensure that when the thin rope 3 is taut, the rope 8 can be in a slack state. The motor 5 is a stepper motor or a servo motor.

[0037] An ultrasonic rangefinder 6 is installed at the bottom of the supporting beam 1, with its probe facing the water surface, to measure the vertical height of the initial position of the ball 4 from the water surface. The data is then fed back to the data processing unit 7. This initial position is at the same height as the connection point at the upper end of the thin rope 3. Vertical height It is also one of the key parameters for calculating flow velocity. (For accurate measurement of vertical height...) The ultrasonic rangefinder 6 needs to be calibrated during installation.

[0038] The data processing unit 7 is used to control the motor 5 to wind and release the ball 4 by winding the rope 8, and to process data to obtain flow rate data.

[0039] This invention can be applied to situations where space is limited, traditional measurement methods are difficult to implement, or the measurement results are unsatisfactory, including:

[0040] (1) Small open channels in irrigation areas: In agricultural irrigation systems, there are a large number of small, irregularly shaped earthen or concrete open channels. These channels are the final link in water resource transportation, and accurate measurement of their flow velocity is crucial for achieving precision irrigation, saving water, and evaluating irrigation efficiency. The device of the present invention is small in size, easy to install, and does not interfere with water flow, making it very suitable for long-term, automated flow velocity monitoring in such channels.

[0041] (2) Seepage Channels in Hydropower Stations: In hydropower stations, seepage monitoring of structures such as dams and powerhouses is a crucial aspect of ensuring the safe operation of the project. Seepage channels are typically narrow, with slow and irregular water flow, making it difficult to install and operate traditional measuring equipment. This invention can accurately measure these minute flow velocities, providing key data support for assessing the safety status of dams and preventing seepage damage.

[0042] (3) Urban drainage network: In urban drainage systems, some branch pipes or connecting pipes have small diameters and complex water flow conditions, making them prone to blockage and overflow. This invention can be used for flow velocity monitoring at key nodes, real-time monitoring of the network's operating status, and providing data for urban flood control, drainage, and network maintenance.

[0043] (4) Industrial wastewater discharge outlets: In the field of environmental monitoring, monitoring the flow rate and velocity of small wastewater discharge outlets of enterprises is an important means of environmental supervision. This invention can adapt to different water qualities and realize continuous online monitoring of discharged wastewater, providing reliable data for total emission control.

[0044] (5) Laboratory and teaching models: In experimental research and teaching demonstrations in disciplines such as hydraulics and fluid mechanics, small water tanks or models are often needed to simulate water flow phenomena. This invention can serve as a high-precision measuring tool for accurately measuring the velocity distribution in models, verifying theoretical formulas, and improving the accuracy of experiments and teaching.

[0045] Example 2: Example 2 provides a method for automated measurement of flow velocity in open channels in confined spaces, using the device for automated measurement of flow velocity in open channels in confined spaces described in Example 1, and includes the following steps:

[0046] S1: Obtain the current vertical height from the initial position of ball 4 to the water surface using ultrasonic rangefinder 6. .

[0047] S2: In At that moment, motor 5 starts, propelling ball 4 at a constant speed. Lowered vertically. During the lowering process, the tension value monitored by tension gauge 2 remained basically constant.

[0048] S3: Based on vertical height and speed Determine the moment when ball 4 touches the water surface. At any moment Motor 5 accelerates to fully release rope 8, so that ball 4 is no longer affected by the force of rope 8. Ball 4 moves forward with the water flow until the thin rope 3 is taut (at the instant ball 4 touches the water surface, due to the propulsion of the water flow, the ball no longer falls vertically, but begins to move forward with the water flow. This tendency of motion causes the thin rope 3 to be released completely instantaneously and to be tightened instantly from a slack state). At this time, the tension monitored by the tension gauge 2 will change abruptly, such as... Figure 3 As shown. The moment of the sudden change in tension monitored by tension gauge 2 is obtained. Then based on the length Vertical height ,time and time The average flow velocity at the surface of the open channel was calculated. This completes one cycle of flow rate measurement.

[0049] The radius of ball 4 When ball 4 floats on the water surface, the height of its underwater portion is negligible. Therefore, at time... = .

[0050] like Figure 2 As shown, the distance that ball 4 moves horizontally under the action of water flow. This can be determined by the Pythagorean theorem: .

[0051] Average flow velocity at the surface of open channel equal to distance Divide by the time it takes to move that distance, which is the moment when ball 4 touches the water surface. The moment when the thin rope 3 is taut and the tension changes abruptly. The time difference between them. Therefore, the average flow velocity on the surface of the open channel. The calculation formula is:

[0052] .

[0053] S4: Motor 5 reverses to reset ball 4 to its initial position, preparing for the next flow rate measurement.

[0054] Data processing unit 7 is integrated into a waterproof and dustproof control box, including a memory, processor, power supply module, and communication module. The memory stores a computer program. When the computer program is executed by the processor, it implements the steps of the method for automated measurement of flow velocity in open channels in confined spaces, and obtains the average flow velocity on the surface of the open channel. The communication module (such as GPRS, NB-IoT, etc.) is used to send monitoring data, flow rate data, etc. to the remote monitoring center. The processor uses a microprocessor (MCU) or a single-chip microcomputer.

Claims

1. A method for automated measurement of flow velocity in open channels in confined spaces, characterized in that, An automated flow velocity measurement device suitable for open channels in confined spaces is adopted. The device includes a support beam (1), a small ball (4), a data processing unit (7), a rope (8), and a low-elasticity thin rope (3). The support beam (1) spans and is fixed above the open channel to be measured. A tension gauge (2), a motor (5), and an ultrasonic rangefinder (6) are fixed to the bottom of the support beam (1). The motor (5) is positioned along the length of the support beam (1), with its output end facing the tension gauge (2). The length of the thin rope (3) is... The upper end of the thin rope (3) is connected to the tension gauge (2), and the lower end is connected to the ball (4); the density of the ball (4) is less than that of water; the tension gauge (2) is used to monitor the tension on the thin rope (3) in real time and feed it back to the data processing unit (7); the upper end of the rope (8) is connected to the output end of the motor (5), and the lower end is connected to the ball (4); the rope (8) is longer than the thin rope (3); the upper connection point of the thin rope (3) is at the same height as the upper connection point of the rope (8); the ultrasonic rangefinder (6) is used to measure the vertical height of the initial position of the ball (4) from the water surface. And feed it back to the data processing unit (7). The initial position is at the same height as the upper connection point of the thin rope (3). The data processing unit (7) is used to control the motor (5) to wind and release the ball (4) in the manner of winding the rope (8), and to perform data processing to obtain flow rate data. The method includes the following steps: S1: Obtain the current vertical height from the initial position of the ball (4) to the water surface using the ultrasonic rangefinder (6). ; S2: In At that moment, the motor (5) starts, moving the ball (4) at a constant speed. Drop vertically; S3: Based on vertical height and speed Determine the moment when ball (4) contacts the water surface. At any moment The motor (5) accelerates to fully release the rope (8); the moment of the tension change monitored by the tension gauge (2) is obtained. Then based on the length Vertical height ,time and time The average flow velocity at the surface of the open channel was calculated. This completes one cycle of flow rate measurement; S4: The motor (5) reverses and resets the ball (4) to its initial position, preparing for the next flow rate measurement.

2. The method for automated measurement of flow velocity in open channels in confined spaces according to claim 1, characterized in that, time = ,in Let be the radius of the small ball (4); The distance the small ball (4) moves horizontally under the action of the water flow for: ; Average flow velocity at the surface of open channel The calculation formula is: 。 3. The method for automated measurement of flow velocity in open channels in confined spaces according to claim 1, characterized in that, The data processing unit (7) includes a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, it implements the steps of the method for automated measurement of flow velocity in open channels in confined spaces, and obtains the average flow velocity on the surface of the open channel. .

4. The method for automated measurement of flow velocity in open channels in confined spaces according to claim 3, characterized in that, The data processing unit (7) also includes a communication module, which is used to send monitoring data and flow rate data to the remote monitoring center.

5. The method for automated measurement of flow velocity in open channels in confined spaces according to claim 3, characterized in that, The processor is a microprocessor or a single-chip microcomputer.

6. The method for automated measurement of flow velocity in open channels in confined spaces according to claim 1, characterized in that, The two ends of the supporting beam (1) are fixed to the two side walls of the open channel to be tested.

7. The method for automated measurement of flow velocity in open channels in confined spaces according to claim 1, characterized in that, The motor (5) is a stepper motor or a servo motor.

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