A kind of open channel flow precision measuring device and method based on silt thickness calculation

Abstract

The present application relates to a kind of based on silt thickness calculation open channel flow accurate measurement device and method, comprising: rectangular hexahedron frame is placed in the water bottom of open channel, the upper and lower surface of rectangular hexahedron frame is closed by top plate and bottom plate, left and right surface is closed by side plate, front and back surface is open, form water flow channel, flow velocity sensor group that can simultaneously measure different water depth layer is set on side plate, water level height sensor and data acquisition processor are set on top plate, bottom plate is flush with the bottom of open channel and is equipped with soil force meter;Data acquisition processor is electrically connected with flow velocity sensor group, water level height sensor, soil force meter.This application can accurately monitor the silt thickness of the bottom of open channel and correct flow measurement in real time, so as to still provide reliable flow data in the case of channel siltation.This has important significance for long-term operation of open channel flow monitoring, and can be widely applied in water conservancy engineering and environmental monitoring field requiring high-precision measurement.

Description

Technical Field

[0001] This invention relates to a device and method for accurately measuring the flow rate of open channels based on silt thickness calculation. It is a hydraulic measurement device and method, and a device and method for monitoring the operating status of open channels. Background Technology

[0002] Open channel flow measurement has wide applications in fields such as water conservancy and irrigation, urban drainage, sewage treatment, and river monitoring. Currently, the most common method for measuring open channel flow is to directly measure the flow using an open channel flow meter or by using standard water measurement structures such as Parshall flume or triangular weir, in conjunction with an ultrasonic level gauge or pressure level gauge, to calculate the flow rate based on a preset level-flow curve by measuring the water level height.

[0003] However, in practical applications, especially in channels or drainage networks with high sediment content, siltation gradually occurs at the bottom of the channel. This siltation causes the actual channel bottom elevation to rise, rendering the measured water level reference surface ineffective. Specifically, the "water level-flow cross-sectional area" relationship calibrated during flow meter installation is based on the initial channel bottom elevation. Once siltation occurs, even if the water level gauge reading is H, the actual flow cross-sectional area is smaller than the initial calibration value because the true effective water depth is H - ΔH (where ΔH is the siltation thickness). The flow meter is unaware of this change and continues to calculate the flow rate according to the initial relationship, resulting in a significantly overestimated calculation and causing a huge measurement error.

[0004] Currently, the main methods for solving this problem are periodic manual dredging or the use of expensive multi-section scanning flow measurement equipment (such as Doppler profilers). The former cannot achieve real-time monitoring, while the latter is costly and complex to maintain. Therefore, there is an urgent need for a low-cost, highly reliable solution that can automatically sense the thickness of sediment in real time and compensate for flow measurement online. Summary of the Invention

[0005] To overcome the problems of existing technologies, this invention proposes a device and method for accurately measuring open channel flow based on silt thickness calculation. The device and method described herein...

[0006] The objective of this invention is achieved as follows: A precise measurement device for open channel flow based on silt thickness calculation includes: a rectangular hexahedral frame placed on the bottom of the open channel; the upper and lower surfaces of the rectangular hexahedral frame are closed by a top plate and a bottom plate, the left and right sides are closed by side plates, and the front and back are open to form a water flow channel; the side plates are equipped with a flow velocity sensor group capable of simultaneously measuring different water depths; the top plate is equipped with a water level sensor and a data acquisition processor; the bottom plate is flush with the bottom of the open channel and is equipped with a soil gauge; the data acquisition processor is electrically connected to the flow velocity sensor group, the water level sensor, and the soil gauge.

[0007] Furthermore, the rectangular hexahedral frame is a metal frame or an engineering plastic frame.

[0008] Furthermore, the top plate, bottom plate, left and right side plates are made of metal or engineering plastic plates and are inlaid on the rods of the rectangular hexahedral frame.

[0009] Furthermore, the flow velocity sensor group includes at least one pair of profile ultrasonic transducers for measuring the flow velocity at different cross sections and different water depths within a rectangular hexahedral frame.

[0010] Furthermore, the water level sensor is a radar water level gauge or an electronic water gauge.

[0011] Furthermore, the base plate has a groove in the center, and a soil pressure sensor element with a sensing diaphragm at the top is installed in the groove. The pressure-sensing diaphragm at the top is precisely flush with the surface of the base plate, and the soil pressure sensor element is sealed with an O-ring between itself and the groove.

[0012] Furthermore, the soil pressure gauge is one of a resistance strain gauge, piezoelectric, or capacitive pressure sensor.

[0013] Furthermore, the soil mechanics measurement range is 0~50kPa, and the accuracy is 0.1%FS.

[0014] Furthermore, the data acquisition processor is also equipped with an alarm module for indicating excessive siltation and a communication module for data transmission.

[0015] A method for accurately measuring open channel flow based on silt thickness calculation using the above-mentioned device, the method comprising the following steps:

[0016] Step 1, Parameter Initialization and Calibration: Install the rectangular hexahedral frame into the open channel, ensuring that the bottom surface of the rectangular hexahedral frame is precisely flush with the bottom of the channel. Connect all parts of the device and load the width B and height H of the water flow channel of the rectangular hexahedral frame into the data processor.

[0017] Step 2, Data Acquisition: Calibrate the water level sensor and the pressure P of the soil gauge;

[0018] Step 3, Calculate the hydrostatic pressure: Based on the real-time water level provided by the open channel flow meter, calculate the pressure generated at the soil gauge installation location. ;

[0019] in: ρ is the density of water; g is the acceleration due to gravity; h is the water depth from the initial elevation of the canal bottom. The thickness of the sediment; among which The average bulk density of the sediment;

[0020] Step 4, calculate the additional pressure caused by siltation: Subtract the hydrostatic pressure mentioned above from the total pressure measured by the soil pressure gauge to obtain the additional pressure caused by the weight of the silt, i.e. ;

[0021] Step 5, Calculate the sediment thickness: Based on the additional sediment pressure and the average bulk density of the sediment, calculate the current sediment thickness. The formula is expressed as: ;

[0022] Step 6, Correcting the Effective Water Depth: The water level measured by the open channel flow meter is corrected using the siltation thickness to obtain the true effective water depth; the effective water depth equals the original water level height minus the siltation thickness, i.e.:

[0023] ;

[0024] Step 7, Correct the flow area: Based on the effective water depth and the cross-sectional shape of the open channel, recalculate the current flow area. ;

[0025] Step 8, Correct Flow Calculation: Calculate the actual flow rate using the corrected flow area, or correct the initial flow rate output by the open channel flow meter.

[0026] The corrected instantaneous flow rate is: .

[0027] Step 9, Data Output and Storage: Output real-time flow and siltation thickness, and store the data.

[0028] The advantages and beneficial effects of this invention are: it can accurately monitor the siltation thickness at the bottom of open channels and correct flow measurements in real time, thus providing reliable flow data even when siltation occurs in the channel. This is of great significance for long-term open channel flow monitoring and can be widely applied in water conservancy projects and environmental monitoring fields that require high-precision measurement.

[0029] The advantages of this invention include: high accuracy, fundamentally solving the system error in flow measurement caused by siltation, achieving real-time, dynamic calibration of traditional flowmeters, and improving long-term measurement accuracy by orders of magnitude. Real-time and automation: It can automatically monitor siltation and correct flow rates around the clock without manual intervention, ensuring data continuity and validity. Low cost: Compared to high-end equipment such as Doppler profilers, soil gauges are less expensive, simpler to modify, and offer significant economic benefits. Convenient maintenance: By monitoring siltation thickness, it can scientifically guide dredging work, changing from periodic, indiscriminate dredging to precise, on-demand dredging, reducing maintenance costs. Wide applicability: It can be widely applied to various open channel flow monitoring scenarios with siltation risks, such as Yellow River irrigation canals, urban combined sewer systems, and sewage treatment plant inlets and outlets. Attached Figure Description

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] Figure 1 This is a schematic diagram of the structure of the device described in Embodiment 1 of the present invention;

[0032] Figure 2 This is a schematic diagram of the installation of the soil gauge in the device described in Embodiment 1 of the present invention. Figure 1 Cross-sectional view of BB in the middle;

[0033] Figure 3 This is a flowchart of the method described in Embodiment 10 of the present invention. Detailed Implementation

[0034] Example 1:

[0035] This embodiment describes a precise measurement device for open channel flow rate based on silt thickness calculation. Figure 1 , 2 As shown. It includes: a rectangular hexahedral frame 1 placed at the bottom of an open channel. The top and bottom of the rectangular hexahedral frame are closed by a top plate 101 and a bottom plate 102, and the left and right sides are closed by side plates 103 and 104. The front and back are open, forming a water flow channel. The water flow direction is as follows... Figure 1 , 2 As indicated by the hollow arrow A, water flows through the front and back of the rectangular hexahedral frame. The directions of up, down, left, and right are determined according to the direction of water flow. A flow velocity sensor group 2, capable of simultaneously measuring different water depths, is installed on the side plates. A water level sensor 3 and a data acquisition processor 4 are installed on the top plate. The bottom plate is flush with the bottom of the open channel 6 and is equipped with a soil gauge 5. The data acquisition processor is electrically connected to the flow velocity sensor group, the water level sensor, and the soil gauge.

[0036] This embodiment mainly includes three parts: open channel flow measurement, siltation thickness measurement, and data acquisition and calculation.

[0037] The open channel flow measurement section is used to measure water level, flow velocity, and flow rate; its functions are integrated or enhanced by a data processor. Water level is measured using a water level sensor. The water level sensor can be a water level gauge or an electronic water level gauge.

[0038] In this embodiment, the flow rate is measured as follows: a rectangular hexahedral frame is fixedly installed inside an open channel, with the bottom surface of the frame flush with the bottom of the channel. The frame is closed at the top, bottom, left, and right, creating a water flow channel at the front and back. Figure 1As shown, a frame delineates a specific cross-section of the water flow to determine the cross-sectional area, which serves as a key parameter for flow rate calculation. The water flow velocity is measured using the time-of-flight method or the frequency difference method, and then the flow rate within the channel is calculated.

[0039] The frame can be a metal frame, such as aluminum alloy, steel structure, or engineering plastics. The top, bottom, left, and right sides of the frame are enclosed with metal or engineering plastic plates, leaving the front and back open to form a flow channel for the water. Because it is a rectangular frame, the flow channel is completely consistent front to back; that is, the overall cross-sectional shape of the flow channel is the same front to back. The element for measuring the flow velocity can be an ultrasonic transducer or a radar sensor for measuring flow velocity.

[0040] The open channel flow measurement section described in this embodiment is actually a flow measurement facility. Besides using a frame to capture the water flow cross-section and measure the flow velocity to measure the flow rate, various flow measurement devices can be used, including but not limited to: ultrasonic time-of-flight or Doppler flow meters, radar flow meters, electromagnetic flow meters, and weir / flute flow meters. Regardless of the principle used, the open channel flow meter must be able to provide real-time water level height and cross-sectional average flow velocity (or flow rate) data. For example, for a box-type open channel multi-channel ultrasonic flow meter, its built-in electronic water gauge or ultrasonic water level measurement module measures the water level, while the ultrasonic probe measures the flow velocity, thereby calculating the initial flow rate; for a radar flow meter, it measures the surface velocity and water level using radar waves, and then calculates the flow rate by combining the cross-sectional shape; for a weir / flute flow meter, it calculates the flow rate by measuring the water level upstream of the weir / flute using empirical formulas, and can also supplement this with flow velocity measurement to improve accuracy.

[0041] The siltation thickness monitoring section consists of one or more soil gauges, fixedly mounted at the bottom center of a rectangular hexahedral frame. Each soil gauge outputs an electrical signal proportional to the vertical pressure exerted by the silt above it. The soil gauge is a highly sensitive pressure sensor, installed with its sensing surface flush with the bottom of the open channel to directly withstand the pressure from the water and silt. The soil gauge's measurement accuracy should be sufficiently high to detect pressure changes caused by minute variations in siltation thickness.

[0042] Data acquisition and processing section: This refers to the data processor, which has a built-in or connected storage unit for the initial geometric parameters of the storage channel and the standard water level-flow relationship.

[0043] Data acquisition and computation section: This refers to the data processor (such as a PLC, embedded system, or remote terminal unit, RTU), which has built-in or connected storage units to store the initial geometric parameters of the channel (such as the initial elevation of the channel bottom). The relationship between channel width (B, etc.) and standard water level-flow rate.

[0044] The data acquisition and calculation section may also include an alarm and communication module. When the calculated siltation thickness exceeds a preset threshold (e.g., the siltation thickness reaches a certain proportion of the channel's design water depth), the alarm module issues a warning signal, reminding maintenance personnel to clean the channel promptly or take other measures. The communication module transmits real-time water level, flow rate, siltation thickness, corrected flow rate, and other data to a remote monitoring center, enabling remote monitoring and storage of the data.

[0045] The data acquisition processor continuously performs calculations and corrections to achieve real-time compensation for flow rate. In practical implementation, the data processing device can employ embedded computers, programmable logic controllers (PLCs), or digital signal processors (DSPs) to ensure the real-time performance and reliability of the calculations. The calculation module can incorporate built-in filtering algorithms (such as Kalman filtering) to smooth signals like pressure and water level, eliminating the effects of noise and instantaneous fluctuations, and improving the stability of sediment thickness and flow rate calculations.

[0046] Example 2:

[0047] This embodiment is an improvement on Embodiment 1, and is a refinement of Embodiment 1 regarding the rectangular hexahedral frame. The rectangular hexahedral frame described in this embodiment is a metal frame or an engineering plastic frame.

[0048] The main body of the rectangular hexahedral frame consists of 12 sturdy and robust columns and beams. The columns and beams are either welded or riveted together to form a strong bond, which can maintain the stability of the structure without deformation in the face of impacts such as water flow.

[0049] Example 3:

[0050] This embodiment is an improvement on the above embodiment, and is a refinement of the top plate, bottom plate, left and right side plates in the above embodiment. The top plate, bottom plate, left and right side plates in this embodiment are made of metal or engineering plastic plates and are inlaid on the rods of a rectangular hexahedral frame.

[0051] Each panel should be smoothly fitted into the inner edge of the frame, such as Figure 1 , 2 As shown, this is to create a cross-section that intercepts the water flow. The connection between each panel and the columns and beams also needs to be a robust one, such as welding or riveting, to resist the impact of the water flow.

[0052] Example 4:

[0053] This embodiment is an improvement on the above embodiment and a refinement of the flow velocity sensor group in the above embodiment. The flow velocity sensor group in this embodiment includes at least one pair of cross-sectional ultrasonic transducers for measuring the flow velocity at different cross sections and different water depths within a rectangular hexahedral frame.

[0054] The flow velocity of water in an open channel varies in many ways, mainly between the upper, middle and lower layers of the water flow. Therefore, in this embodiment, at least one row of sensors for measuring water velocity is set from top to bottom on the left and right side plates of the rectangular hexahedron frame to measure the flow velocity at each layer of the water flow, thereby accurately obtaining the flow rate value.

[0055] Example 5:

[0056] This embodiment is an improvement on the above embodiment, and is a refinement of the above embodiment regarding the water level sensor. The water level sensor described in this embodiment is a radar water level gauge or an electronic water gauge.

[0057] Radar level gauges employ a non-contact measurement principle, accurately determining water levels by emitting electromagnetic waves towards the water surface and receiving the echoes. The radar level gauge should be installed on top of a rectangular hexahedral frame and only functions when the open channel water flow does not submerge the entire frame. Once the frame is submerged, the height of the frame can be directly used as the cross-sectional height.

[0058] The electronic water gauge is vertically fixed to the left or right side wall of the rectangular hexahedron frame, perpendicular to the bottom of the channel.

[0059] Example 6:

[0060] This embodiment is an improvement on the above embodiment, and is a refinement of the base plate for installing the soil gauge in the above embodiment. The base plate in this embodiment has a groove 501 in the center, and a soil gauge sensing element 502 with a sensing diaphragm on the top is set in the groove. The pressure-sensing diaphragm on the top is precisely flush with the surface of the base plate and is fixed to the base plate and side wall by welding or sealant, providing an enhanced mounting surface. The soil gauge element and the groove are sealed with an O-ring 503 to ensure waterproofing of the main body and prevent water from seeping in from between the sensor housing and the mounting hole wall.

[0061] The key to installing a soil dynamics gauge is that the top sensing plate is precisely flush with the surface of the base plate, that is, flush with the bottom of the open channel, so as to accurately measure the thickness of the siltation.

[0062] Example 7:

[0063] This embodiment is an improvement on the above embodiment and a refinement of the soil gauge in the above embodiment. The soil gauge described in this embodiment is one of a resistance strain gauge, piezoelectric, or capacitive pressure sensor.

[0064] The soil gauge is installed at the bottom center of a rectangular hexahedral frame, and the structure is designed to withstand long-term underwater corrosion, biofouling, and the impact and abrasion of sediment particles.

[0065] Example 8:

[0066] This embodiment is an improvement upon the above embodiments, and a refinement of the soil gauge described in the above embodiments. The soil gauge range described in this embodiment... precision .

[0067] Example 9:

[0068] This embodiment is an improvement on the above embodiment, and is a refinement of the data acquisition processor in the above embodiment. The data acquisition processor in this embodiment is further provided with an alarm module for indicating excessive siltation and a communication module for data transmission.

[0069] In addition to the computing and storage units, the data acquisition processor is equipped with an alarm and communication module, which is connected to the open channel flow measurement section and the siltation thickness monitoring section. It has a built-in or connected storage unit for storing the initial geometric parameters of the channel and the standard water level-flow relationship.

[0070] Example 10:

[0071] This embodiment describes a method for accurately measuring open channel flow based on silt thickness calculation using the device described in the above embodiments. The steps of the method are as follows: Figure 3 As shown:

[0072] Step 1, Parameter Initialization and Calibration: Install the rectangular hexahedral frame into the open channel, ensuring that the bottom surface of the rectangular hexahedral frame is precisely flush with the bottom of the channel. Connect all parts of the device and load the width B and height H of the water flow channel of the rectangular hexahedral frame into the data processor.

[0073] Since the water flow channel of the frame is the cross-section of the water flow, its width parameter is very important. Changes in water level affect the height of the water flow cross-sectional area, so it must be very accurate.

[0074] Step 2, Data Acquisition: Calibrate the water level sensor and the pressure P of the soil gauge;

[0075] After installation, the water level sensor must be calibrated to accurately obtain water level parameters. Since the soil gauge is located at the bottom of the channel, it will be subject to water pressure. Because the water level is dynamic, the initial position can be set when the channel is dry and free of silt, and the pressure can be zeroed for compensation during measurement and calculation.

[0076] Step 3, Calculate the hydrostatic pressure: Based on the real-time water level provided by the open channel flow meter, calculate the pressure generated at the soil gauge installation location. ;

[0077] in: ρ is the density of water; g is the acceleration due to gravity; h is the water depth from the initial elevation of the canal bottom. The thickness of the sediment; among which This refers to the average bulk density (weight per unit volume) of the silt, which can be preset based on engineering experience or sampling measurements. If the silt in the open channel is mainly composed of mud and sand, its saturated bulk density is typically around [value missing]. The additional pressure can be converted into the thickness of the sediment layer using the above formula.

[0078] Step 4, calculate the additional pressure caused by siltation: Subtract the hydrostatic pressure mentioned above from the total pressure measured by the soil pressure gauge to obtain the additional pressure caused by the weight of the silt, i.e. ;

[0079] Step 5, Calculate the sediment thickness: Based on the additional sediment pressure and the average bulk density of the sediment, calculate the current sediment thickness. The formula is expressed as: ;

[0080] Step 6, Correcting the Effective Water Depth: The water level measured by the open channel flow meter is corrected using the siltation thickness to obtain the true effective water depth; the effective water depth equals the original water level height minus the siltation thickness, i.e.:

[0081] This step is equivalent to restoring the water level benchmark from the new, silted-up canal bottom to the original canal bottom, thereby obtaining the actual water depth.

[0082] Step 7, Correct the flow area: Based on the effective water depth and the cross-sectional shape of the open channel, recalculate the current flow area. For example, for a standard rectangular channel, the flow area is the channel width multiplied by the effective water depth; for trapezoidal or circular channels, it can be calculated using the corresponding geometric formulas. By introducing the effective water depth, the effect of cross-sectional reduction caused by siltation is eliminated.

[0083] Step 8, Correct Flow Calculation: Calculate the actual flow rate using the corrected flow area, or correct the initial flow rate output by the open channel flow meter.

[0084] The corrected instantaneous flow rate is: .

[0085] For flow meters using the velocity-area method, the corrected flow rate can be obtained by directly multiplying the new flow area by the average cross-sectional velocity. For instruments such as weirs and flumes that directly calculate the flow rate based on the water level, the corrected flow rate needs to be calculated based on the effective water depth, or the original flow rate value needs to be adjusted proportionally. Through the above corrections, the true flow rate value considering the effects of siltation can be obtained.

[0086] Step 9, Data Output and Storage: Output real-time flow and siltation thickness, and store the data.

[0087] Data output can be displayed on the human-machine interface by creating data tables or data analysis coordinate graphs, or printed out as paper documents. The acquired data feedback values ​​are stored in the data acquisition module as raw data.

[0088] Design Example 1:

[0089] In a rectangular concrete drainage channel, a precise flow measurement device based on silt thickness calculation, as described in this embodiment, is installed.

[0090] Selection: A rectangular hexahedral frame is installed at the bottom of the open channel, which includes a soil gauge installed at the bottom of the open channel. The soil gauge range is... precision Flow meter selection: Multi-channel ultrasonic channel flow meter, measuring range 0-3 meters.

[0091] Installation: Install the soil meter at the center of the bottom of the rectangular hexahedral frame, ensuring its sensing surface is flush with the bottom surface of the box. The box-type open channel flow meter should be installed with the bottom surface of the channel parallel to the channel bottom.

[0092] Initialization: When the channel is dry and free of silt, start the system and record the initial frequency modulus of the soil dynamics meter. Set the width of the rectangular hexahedron frame in the data processor. Then input the Manning formula calculation program for the rectangular channel. Set the saturated bulk density of the silt. .

[0093] Design Example 2:

[0094] In a rectangular concrete drainage channel, a precise flow measurement device for the channel based on silt thickness calculation, as described in this embodiment, is installed.

[0095] Selection: A vibrating wire earth pressure gauge is selected as the earth pressure gauge, with a measurement range of [missing information]. precision The water level gauge is a non-contact ultrasonic water level gauge with a range of 0-3 meters.

[0096] Installation: Securely embed the soil leveler in the center of the channel bottom, ensuring its sensing surface is flush with the channel bottom. Install the ultrasonic water level gauge directly above the channel, aligned with the water surface near the soil leveler's installation location.

[0097] Initialization: When the channel is dry and free of silt, start the system and record the initial frequency modulus F0 of the soil dynamics meter. In the data processor, set the channel bottom width (or frame width) B = 1.0m and input the Manning formula calculation program for this rectangular channel. Set the saturated unit weight of the silt. .

[0098] The effectiveness of this embodiment is further illustrated by a specific application example below:

[0099] Application Example: An irrigation canal has a rectangular cross-section, a width of 2 meters, and a designed bottom elevation of 0 meters. The system described in this invention is installed in the canal. Initially, without siltation, the soil dynamics gauge measures a pressure of 0. A box-type open channel flow meter is installed in the canal to measure water level and flow velocity. Initially, the water level h = 1.0 meter, and the soil dynamics gauge measures a total pressure of... The pressure is consistent with the theoretical hydrostatic pressure, indicating no sedimentation. The flow rate calculated by the flow meter at this point... Assuming flow rate ,but This is the actual traffic.

[0100] After operating for a period of time, silt accumulates at the bottom of the canal. Assume the silt thickness... Meters, average bulk density of silt (Sampling and measurement can be performed in actual engineering projects). At this point, the water level h measured by the open channel flow meter is still 1.0 meter (because the instrument is based on the current channel bottom), but the actual effective water depth is only 0.8 meters. Without correction, the flow meter calculates the flow area based on h=1.0 meter. ,flow This is inconsistent with reality.

[0101] In this application example, assuming the water level h measured by the open channel flow meter is already the elevation relative to the original channel bottom, then when the siltation thickness is... At that time, the actual effective water depth was The soil gauge is located at the bottom of the original canal and bears pressure including the weight of the water (based on the effective water depth). ) and the weight of the sediment (based on ).therefore, By rearranging, we obtain: .

[0102] In this application example, h = 1.0 m , Substituting into This is consistent with the actual siltation thickness. Therefore, the data processing device calculated... Meters. Then, effective water depth. Corrected flow area

[0103] Assuming the flow velocity v remains at 0.5 m / s (the actual flow velocity may increase slightly due to the reduced cross-section, but in this case, we assume the flow velocity measurement is accurate), the corrected flow rate is... = 0.5 × 1.6 = Compared to the uncorrected result The correction results of this invention are more accurate, eliminating the 20% flow measurement error caused by siltation.

[0104] Finally, it should be noted that the above is only used to illustrate the technical solution of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred arrangements, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of the present invention (such as the form of open channel, the method of flow velocity detection, the application of various formulas, the order of steps, etc.) without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A precise measurement device for open channel flow rate based on silt thickness calculation, comprising: A rectangular hexahedral frame placed on the bottom of an open channel, the frame having a closed top and bottom plate, closed side plates on the left and right sides, and open front and back to form a water flow channel. The frame is characterized by having a flow velocity sensor group capable of simultaneously measuring different water depths installed on the side plates, a water level sensor and a data acquisition processor installed on the top plate, and a soil gauge installed on the bottom plate flush with the channel bottom. The data acquisition processor is electrically connected to the flow velocity sensor group, the water level sensor, and the soil gauge.

2. The apparatus according to claim 1, characterized in that, The rectangular hexahedral frame is a metal frame or an engineering plastic frame.

3. The apparatus according to claim 2, characterized in that, The top plate, bottom plate, left and right side plates are made of metal or engineering plastic plates and are inlaid on the rods of a rectangular hexahedral frame.

4. The apparatus according to claim 3, characterized in that, The flow velocity sensor group includes at least one pair of profile ultrasonic transducers for measuring the flow velocity at different cross sections and different water depths within a rectangular hexahedral frame.

5. The apparatus according to claim 4, characterized in that, The water level sensor is either a radar water level gauge or an electronic water level gauge.

6. The apparatus according to claim 5, characterized in that, The base plate has a groove in the center, and a soil pressure sensor element with a sensing diaphragm at the top is installed in the groove. The top pressure diaphragm is precisely flush with the surface of the base plate, and the soil pressure sensor element and the groove are sealed with an O-ring.

7. The apparatus according to claim 6, characterized in that, The soil pressure gauge is one of the following: resistance strain gauge, piezoelectric, or capacitive pressure sensor.

8. The apparatus according to claim 7, characterized in that, The soil force measurement process , accuracy 0.1%FS.

9. The apparatus according to claim 8, characterized in that, The data acquisition processor also includes an alarm module for indicating excessive siltation and a communication module for data transmission.

10. A method for accurately measuring open channel flow based on silt thickness calculation using the device of claim 9, characterized in that, The steps of the method are as follows: Step 1, Parameter Initialization and Calibration: Install the rectangular hexahedral frame into the open channel, ensuring that the bottom surface of the rectangular hexahedral frame is precisely flush with the bottom of the channel. Connect all parts of the device and load the width B and height H of the water flow channel of the rectangular hexahedral frame into the data processor. Step 2, Data Acquisition: Calibrate the water level sensor and the pressure P of the soil gauge; Step 3, Calculate the hydrostatic pressure: Based on the real-time water level provided by the open channel flow meter, calculate the pressure generated at the soil gauge installation location. ; in: ρ is the density of water; g is the acceleration due to gravity; h is the water depth from the initial elevation of the canal bottom. The thickness of the sediment; among which The average bulk density of the sediment; Step 4, calculate the additional pressure caused by siltation: Subtract the hydrostatic pressure mentioned above from the total pressure measured by the soil pressure gauge to obtain the additional pressure caused by the weight of the silt, i.e. ; Step 5, Calculate the sediment thickness: Based on the additional sediment pressure and the average bulk density of the sediment, calculate the current sediment thickness. The formula is expressed as: ; Step 6, Correcting the Effective Water Depth: The water level measured by the open channel flow meter is corrected using the siltation thickness to obtain the true effective water depth; the effective water depth equals the original water level height minus the siltation thickness, i.e.: ； Step 7, Correct the flow area: Based on the effective water depth and the cross-sectional shape of the open channel, recalculate the current flow area. ; Step 8, Correct Flow Calculation: Calculate the actual flow rate using the corrected flow area, or correct the initial flow rate output by the open channel flow meter. The corrected instantaneous flow rate is: ; Step 9, Data Output and Storage: Output real-time flow and siltation thickness, and store the data.

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