Chromatographic flowmeter method based on ultrasonic scanning

Abstract

The invention discloses a chromatographic flowmeter method based on ultrasonic scanning, which comprises the following steps of: uniformly arranging inclined closed conduits in a river channel, and driving an ultrasonic probe to step along the conduits by a motor; setting a scanning starting position, a stepping interval, a scanning speed and a sampling frequency; acquiring echo intensity, echo delay and Doppler frequency shift at each depth to form original data; acoustically analyzing and identifying a water surface and sludge interface, and calculating a layered flow velocity to generate a layered data set; constructing a section chromatography model through interpolation fitting, and determining a layered effective overflowing sectional area and an average flow velocity; layering integration is carried out to obtain section total flow and generate real-time flow data; and monitoring signal quality to trigger self-cleaning. The interface and the speed are obtained in the same way, the total flow is output through layered integral, the structure is simplified, data are consistent, and the method is suitable for online flow measurement.

Description

Technical Field

[0001] This invention relates to the field of hydrological flow measurement technology, and in particular to a chromatographic flowmeter method based on ultrasonic scanning. Background Technology

[0002] Current methods for flow measurement in open channels and rivers mainly employ the water level-discharge relationship of water measurement structures, stratified velocity measurement using fixed ultrasonic arrays across cross sections, scanning with mobile acoustic Doppler profilers, and surface radar velocity calculations combined with empirical roughness coefficients. In engineering applications, independent water level gauges or pressure gauges are often used to provide the water surface position, which is then combined with velocity measurement results to estimate the flow rate. Fixed arrays typically deploy multiple sensors on the bank or bridge, sampling in parallel at several depth points, and approximating the velocity distribution through interpolation. These methods work in scenarios with stable cross sections, but they reveal limitations in scenarios with rapidly changing cross-sectional morphology and siltation.

[0003] Fixed ultrasonic arrays are numerous, requiring extensive installation and alignment work. Fluctuations in water level and riverbed undulations cause shifts in acoustic path geometry, necessitating repeated calibration. Water surface position and silt interface measurements often rely on independent sensors or offline measurements. Velocity measurements and interface identification originate from different sources, resulting in temporal and spatial asynchrony and making consistent error control difficult. Mobile measurements depend on manual platforms, lacking continuity and unable to operate online for extended periods. Sediment and biological adhesion in the field cause echo attenuation and channel blockage. Many systems lack self-cleaning linkages triggered by signal quality thresholds, making long-term data stability difficult to guarantee.

[0004] Existing technologies lack an integrated data link for online monitoring, a unified acoustic dataset for simultaneously acquiring water surface position, silt interface position, and stratification velocity within the same measurement range, a step-by-step arrangement for directly constructing a cross-sectional tomography model from the same dataset and determining the effective flow cross-sectional area, a clear calculation chain based on stratified integration to give the total flow rate, and a self-cleaning control strategy to support signal quality monitoring. To address these shortcomings, it is necessary to complete stratified scanning along the duct's tilt direction under conditions with few sensors on the shore, form a unified stratified dataset, establish a cross-sectional tomography model and an effective flow cross-sectional area calculation process, and combine flow stratified integration and a self-cleaning trigger mechanism to support long-term online flow measurement scenarios.

[0005] Therefore, how to provide a chromatographic flowmeter method based on ultrasonic scanning is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] One objective of this invention is to propose a chromatographic flowmeter method based on ultrasonic scanning. This invention utilizes an ultrasonic probe that can move stepwise within a closed conduit, ultrasonic echo ranging and Doppler velocimetry, cross-sectional tomographic modeling and layered integral calculation. It details the implementation process of simultaneous data acquisition along the inclined direction of the conduit, interface identification, layered velocity calculation and self-cleaning linkage. It has the advantages of fewer sensors, simplified installation, strong cross-sectional adaptability, good data consistency, online continuity and low maintenance burden.

[0007] A chromatographic flowmeter method based on ultrasonic scanning according to an embodiment of the present invention includes the following steps:

[0008] Closed conduits are installed evenly at different locations in the river channel. An ultrasonic probe that can move along the direction of the conduit is installed inside the closed conduit. The ultrasonic probe achieves controlled scanning along the tilt direction of the conduit through a motor-driven mechanism.

[0009] The scanning start position, step interval, scanning speed and sampling frequency are set in the control device, and the ultrasound probe is driven to move layer by layer in the closed duct.

[0010] During the scanning process, ultrasound signals are transmitted and received at various depth positions, and data on echo intensity, echo delay, and Doppler frequency shift are collected to form raw scan data;

[0011] Acoustic analysis is performed on the raw scan data. The upper boundary of the water body and the bottom silt interface are identified based on the echo delay. The flow velocity component at the corresponding depth is calculated based on the Doppler frequency shift, generating a layered dataset containing information on depth, water surface position, silt interface position and flow velocity.

[0012] Interpolation and fitting operations were performed on the stratified dataset to construct a river cross-section tomography model. The effective cross-sectional area and average velocity of each stratum were determined based on the spatial location of the water surface and the silt interface.

[0013] Based on the effective cross-sectional area and average velocity of each layer, perform layered integral calculations to obtain the total flow of the river section and generate real-time flow data.

[0014] If ultrasound signal attenuation or blockage of the closure catheter is detected during scanning or operation, the self-cleaning component is activated to clean the closure catheter and ultrasound probe.

[0015] Optionally, the arrangement of the closed conduit and the tilting stepping scanning mechanism specifically includes:

[0016] Closed conduits are evenly distributed and installed at different locations in the river channel. Each closed conduit is fixed to the bank or river sidewall by a mounting bracket. The axial direction of the closed conduit forms an inclination angle θ with the water flow cross section, and the value of θ ranges from 15° to 30°.

[0017] The upper end of the closed conduit extends out of the water surface to connect the control device and the motor drive mechanism. The lower end of the closed conduit is buried in the riverbed at a depth of h0, where h0 is the vertical distance from the bottom of the conduit to the riverbed reference surface.

[0018] A sliding guide rail is installed along the length of the closed catheter, with the center line of the sliding guide rail parallel to the axis of the closed catheter, to limit the movement path of the ultrasound probe;

[0019] A motor drive mechanism is installed at the upper end of the closed catheter. The motor output shaft is connected to a lead screw or rack and pinion transmission assembly. The lead screw pitch is denoted as p. It is used to drive the ultrasound probe to move stepwise along the inclined direction of the closed catheter.

[0020] An ultrasonic probe slider assembly is installed inside a closed conduit. The slider assembly is connected to a lead screw nut, and the ultrasonic probe is fixed at the front end of the slider. The emitting surface of the ultrasonic probe is perpendicular to the axis of the closed conduit.

[0021] Set the range of motion H of the ultrasonic probe. H is determined by the water surface position h1 and the bottom position of the conduit h0. H = h1 − h0, where h1 is the vertical height of the water surface corresponding to the upper end of the closed conduit.

[0022] Signal and power lines are laid out on the outer wall of the sealed catheter to connect the signal output end of the ultrasound probe to the input end of the control device, thereby achieving synchronous execution of scanning control and data acquisition.

[0023] Optionally, the scanning parameter setting and step control execution specifically include:

[0024] Set the scan start position h in the control device. s Step interval Δh, scan speed v s and sampling frequency f s ;

[0025] The control device consists of a signal processing unit, a calculation unit, and an output interface unit. The signal processing unit receives parameter input signals, the calculation unit generates a sequence of control commands, and the output interface unit sends control signals to the motor drive mechanism.

[0026] Based on the scan start position h s Determine the initial position z0 of the ultrasonic probe inside the closed catheter, where z0 is the vertical coordinate of the ultrasonic probe's emitting surface relative to the bottom of the closed catheter;

[0027] The arithmetic unit operates according to the step interval Δh and the scan speed v s Arrange the sequence of control instructions, which includes each step and its corresponding execution timing;

[0028] The output interface unit outputs step-by-step control signals to the motor drive mechanism, driving the ultrasound probe to move sequentially to the depth position sequence along the inclined direction of the closed duct.

[0029] After the ultrasound probe reaches the i-th position in the depth position sequence, record the current position coordinates zᵢ, zᵢ = z0 +i·Δh, where zᵢ is the ultrasound probe position corresponding to the i-th step and i is the step number;

[0030] After completing the step-by-step control, h s , Δh, v s f s The position sequence zᵢ is stored as scan control data.

[0031] Optionally, the ultrasonic emission, echo acquisition, and Doppler frequency shift calculation specifically include:

[0032] The control device calls the sampling frequency parameters, sets the pulse repetition frequency, time gating start time and time gating width, and generates transmit control commands and receive control commands.

[0033] Ultrasonic transmission is triggered at each predetermined depth position, and the receiving end collects the echo signal according to the sampling frequency to generate the echo data segment corresponding to the depth position;

[0034] Extract the echo envelope amplitude within the time-gated interval and record it as the echo intensity; extract the envelope arrival time and record it as the echo delay.

[0035] The Doppler frequency shift is calculated based on the echo signals generated by two adjacent transmissions. The phase difference of the main frequency components of the two adjacent echoes is multiplied by the pulse repetition frequency and then divided by twice pi to obtain the Doppler frequency shift value at the corresponding depth position.

[0036] A data frame is generated at each predetermined depth position. The data frame contains the depth position, echo intensity, echo delay, and Doppler frequency shift value.

[0037] Data frames are combined in depth order to form the original scan data.

[0038] Optionally, the identification of the water surface and silt interface and the calculation of the stratification rate specifically include:

[0039] Read the data frames from the original scan data in depth order. The data frames contain depth position, echo intensity, echo delay and Doppler frequency shift value.

[0040] Within the time-gated interval at each predetermined depth position, locate the peak time of the water surface echo and determine the water surface echo delay; locate the peak time of the silt interface echo and determine the silt interface echo delay.

[0041] The one-way distance from the probe to the water surface and the one-way distance from the probe to the silt interface are calculated based on the correspondence between the sound velocity of the medium and the echo delay. The one-way distance is expressed as half of the product of the sound velocity and the echo delay.

[0042] The water surface coordinates are obtained by adding the depth position to the one-way distance from the probe to the water surface, and the mud interface coordinates are obtained by adding the depth position to the one-way distance from the probe to the mud interface.

[0043] The stratified flow velocity components are calculated based on the Doppler frequency shift value and the velocity conversion factor, which is determined by the speed of sound, the transmission carrier frequency, and the incident angle.

[0044] A record entry is generated at each predetermined depth location. The record entry includes the depth location, water surface location coordinates, silt interface location coordinates, stratified flow velocity components, and echo intensity.

[0045] Record entries are grouped in depth order to form a hierarchical dataset.

[0046] Optionally, the construction of the cross-sectional tomography model and the calculation of the effective flow cross-sectional area and the stratified average flow velocity specifically include:

[0047] Read the layered dataset and organize the depth position sequence, water surface position coordinate sequence, silt interface position coordinate sequence, and layered velocity component sequence according to the location of the closed conduit.

[0048] Interpolation and fitting are performed on the water surface position coordinate sequence and the silt interface position coordinate sequence in the depth direction of each closed conduit to generate a continuous interface trajectory in the depth direction.

[0049] Interpolation and fitting of the continuous interface trajectory according to the location of the closed conduit are performed to generate the water surface profile curve and the silt interface profile curve in the river cross-section tomography model.

[0050] Divide the layers into intervals according to the depth direction, determine the upper and lower boundary positions and the lateral sampling position sequence of each interval, and give the upper and lower boundary positions by the coordinates of the water surface profile curve and the silt interface profile curve at the corresponding depth.

[0051] Calculate the effective flow cross-sectional area within each layered interval. According to the lateral order of the closed conduit positions, multiply the distance between the water surface position coordinates and the silt interface position coordinates at the corresponding positions by the distance between adjacent closed conduit positions and then sum them up to obtain the effective flow cross-sectional area of ​​the current layered interval.

[0052] Calculate the average flow velocity within each layer interval, and perform a weighted average of the layer velocity components according to the location of the closed conduit. The weighting weight is the distance between the coordinates of the water surface and the coordinates of the silt interface at the corresponding location.

[0053] The water surface profile curve, the silt interface profile curve, the effective cross-sectional area of ​​each layer, and the average flow velocity of each layer are compiled into a river cross-sectional tomography model dataset.

[0054] Optionally, the generation of total flow and real-time flow data for the hierarchical integration calculation section specifically includes:

[0055] The effective cross-sectional area and average velocity of each layer in the river cross-section tomography model dataset are used as calculation parameters.

[0056] The instantaneous flow rate of each layer is calculated by multiplying the effective cross-sectional area by the average velocity of the layer.

[0057] The total cross-sectional flow is obtained by summing the instantaneous flow rates of all layers at the same calculation time.

[0058] Record the correspondence between the calculation time and the total flow rate of the cross section, and generate real-time flow data records;

[0059] Real-time traffic data is compiled and recorded in chronological order to form real-time traffic data.

[0060] Optionally, the signal quality monitoring and self-cleaning linkage control specifically includes:

[0061] Signal monitoring parameters are set in the control device, including the lower limit of echo intensity, the upper limit of echo attenuation ratio, the upper limit of drive motor current, the upper limit of position error, the monitoring window duration, the spraying duration, and the number of wiping cycles.

[0062] During the scanning process, the echo intensity, echo attenuation ratio, drive motor current and position error are recorded according to the depth position, and the duration of each record within the monitoring window is calculated.

[0063] When the echo intensity is lower than the lower limit of echo intensity and the echo attenuation ratio is higher than the upper limit of echo attenuation ratio, and the duration is not less than the monitoring window duration, it is determined to be an ultrasonic signal attenuation event.

[0064] When the drive motor current is higher than the upper limit of the drive motor current and the position error is higher than the upper limit of the position error, and the duration is not less than the monitoring window duration, it is determined to be a closed conduit blockage event;

[0065] To handle ultrasonic signal attenuation events, a self-cleaning process is executed. The control device issues a self-cleaning command and starts the self-cleaning component to complete the spraying and wiping stages. The spraying stage runs according to the spraying duration, and the wiping stage runs according to the number of wiping cycles.

[0066] For closed conduit blockage events, a self-cleaning process is executed. The control device issues a self-cleaning command and starts the self-cleaning component to complete the spray washing stage and the wiping stage. The spray washing stage runs according to the spray washing duration, and the wiping stage runs according to the number of wiping repetitions.

[0067] After the self-cleaning process is completed, the cleaning timestamp and cumulative cleaning count are recorded, scanning control is restored, and parameter monitoring continues.

[0068] The beneficial effects of this invention are:

[0069] This invention drives an ultrasonic probe to scan in a step-by-step manner along the inclined direction of the closed conduit evenly distributed at different locations in the river channel. It simultaneously collects echo intensity, echo delay, and Doppler frequency shift, thereby obtaining the location of the silt interface and the stratification velocity field at the water surface. This reduces the number of ultrasonic probes and the workload of installation and calibration, shortens the deployment cycle, and establishes original scanning data and stratified datasets that are consistent in time and space, thus improving the coverage stability in scenarios of fluctuating water levels and siltation changes.

[0070] Based on the hierarchical dataset, interpolation and fitting are performed to construct a river cross-section tomography model. The effective cross-sectional area of ​​each layer is determined according to the interface coordinates and matched with the average flow velocity of each layer. The total flow rate and real-time flow rate data of the cross section are given by hierarchical integration. The data link from scanning control to acoustic analysis and then to model calculation maintains the same source and the same coordinate system, adapting to cross-sectional deformation and non-uniform flow velocity distribution, reducing dependence on external sensors and parameter transmission errors.

[0071] The control device sets a lower limit for echo intensity, an upper limit for echo attenuation ratio, an upper limit for drive motor current, and an upper limit for position error. It then uses the monitoring window to determine events and activates the self-cleaning component based on the determination results to complete spraying and wiping, recording the timestamp and cumulative number of times. This achieves a closed loop for online monitoring and maintenance, reducing maintenance frequency and downtime, and enhancing long-term continuous operation and data stability. Attached Figure Description

[0072] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0073] Figure 1 This is a flowchart of a chromatographic flowmeter method based on ultrasonic scanning proposed in this invention;

[0074] Figure 2 This is a schematic diagram of the ultrasonic probe stepping mechanism inside a closed duct in a chromatographic flowmeter method based on ultrasonic scanning proposed in this invention.

[0075] Figure 3 This is a schematic diagram of a river cross-section tomography model for a tomography flowmeter method based on ultrasonic scanning proposed in this invention. Detailed Implementation

[0076] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0077] refer to Figure 1-3 A method for a chromatographic flowmeter based on ultrasonic scanning includes the following steps:

[0078] Closed conduits are installed evenly at different locations in the river channel. An ultrasonic probe that can move along the direction of the conduit is installed inside the closed conduit. The ultrasonic probe achieves controlled scanning along the tilt direction of the conduit through a motor-driven mechanism.

[0079] The scanning start position, step interval, scanning speed and sampling frequency are set in the control device, and the ultrasound probe is driven to move layer by layer in the closed duct.

[0080] During the scanning process, ultrasound signals are transmitted and received at various depth positions, and data on echo intensity, echo delay, and Doppler frequency shift are collected to form raw scan data;

[0081] Acoustic analysis is performed on the raw scan data. The upper boundary of the water body and the bottom silt interface are identified based on the echo delay. The flow velocity component at the corresponding depth is calculated based on the Doppler frequency shift, generating a layered dataset containing information on depth, water surface position, silt interface position and flow velocity.

[0082] Interpolation and fitting operations were performed on the stratified dataset to construct a river cross-section tomography model. The effective cross-sectional area and average velocity of each stratum were determined based on the spatial location of the water surface and the silt interface.

[0083] Based on the effective cross-sectional area and average velocity of each layer, perform layered integral calculations to obtain the total flow of the river section and generate real-time flow data.

[0084] If ultrasound signal attenuation or blockage of the closure catheter is detected during scanning or operation, the self-cleaning component is activated to clean the closure catheter and ultrasound probe.

[0085] This invention involves uniformly distributing and installing closed conduits at different locations in the river channel, and using a motor-driven mechanism to advance an ultrasonic probe along the inclined direction of the conduit within the closed conduit. By setting the scanning start position, step interval, scanning speed, and sampling frequency in the control device, echo intensity, echo delay, and Doppler frequency shift are obtained synchronously within the same measurement range to form raw scanning data. Then, the water surface and silt interface identification, layer velocity calculation, cross-sectional tomography model construction, and layer integration are completed sequentially to generate the total cross-sectional flow. At the same time, a self-cleaning component is triggered based on signal quality to keep the conduit unobstructed and the data continuous.

[0086] In this embodiment, the arrangement of the closed conduit and the tilting stepping scanning mechanism specifically includes:

[0087] Closed conduits are evenly distributed and installed at different locations in the river channel. Each closed conduit is fixed to the bank or river sidewall by a mounting bracket. The axial direction of the closed conduit forms an inclination angle θ with the water flow cross section, and the value of θ ranges from 15° to 30°.

[0088] The upper end of the closed conduit extends out of the water surface to connect the control device and the motor drive mechanism. The lower end of the closed conduit is buried in the riverbed at a depth of h0, where h0 is the vertical distance from the bottom of the conduit to the riverbed reference surface.

[0089] A sliding guide rail is installed along the length of the closed catheter, with the center line of the sliding guide rail parallel to the axis of the closed catheter, to limit the movement path of the ultrasound probe;

[0090] A motor drive mechanism is installed at the upper end of the closed catheter. The motor output shaft is connected to a lead screw or rack and pinion transmission assembly. The lead screw pitch is denoted as p. It is used to drive the ultrasound probe to move stepwise along the inclined direction of the closed catheter.

[0091] An ultrasonic probe slider assembly is installed inside a closed conduit. The slider assembly is connected to a lead screw nut, and the ultrasonic probe is fixed at the front end of the slider. The emitting surface of the ultrasonic probe is perpendicular to the axis of the closed conduit.

[0092] Set the range of motion H of the ultrasonic probe. H is determined by the water surface position h1 and the bottom position of the conduit h0. H = h1 − h0, where h1 is the vertical height of the water surface corresponding to the upper end of the closed conduit.

[0093] Signal and power lines are laid out on the outer wall of the sealed catheter to connect the signal output end of the ultrasound probe to the input end of the control device, thereby achieving synchronous execution of scanning control and data acquisition.

[0094] This invention employs a structure in which the closed conduit is evenly distributed and installed at different locations in the river channel, and the conduit axis is set in an inclination range of 15 to 30 degrees. The conduit is equipped with a sliding guide rail and a lead screw drive, and the stepping scale is unified by the pitch parameter. The ultrasonic probe is fixed at the front end of the slider and the emitting surface is perpendicular to the conduit axis. Repeatable tilt scanning is achieved by setting the movement range. The outer wall of the conduit is laid with signal lines and power lines and is stably connected to the control device. Thus, a scanning channel with consistent coverage, defined geometric relationship and controlled movement path is formed at a small number of installation points.

[0095] In this embodiment, the scanning parameter setting and step control execution specifically include:

[0096] Set the scan start position h in the control device. s Step interval Δh, scan speed v s and sampling frequency f s ;

[0097] The control device consists of a signal processing unit, a calculation unit, and an output interface unit. The signal processing unit receives parameter input signals, the calculation unit generates a sequence of control commands, and the output interface unit sends control signals to the motor drive mechanism.

[0098] Based on the scan start position h s Determine the initial position z0 of the ultrasonic probe inside the closed catheter, where z0 is the vertical coordinate of the ultrasonic probe's emitting surface relative to the bottom of the closed catheter;

[0099] The arithmetic unit operates according to the step interval Δh and the scan speed v s Arrange the sequence of control instructions, which includes each step and its corresponding execution timing;

[0100] The output interface unit outputs step-by-step control signals to the motor drive mechanism, driving the ultrasound probe to move sequentially to the depth position sequence along the inclined direction of the closed duct.

[0101] After the ultrasound probe reaches the i-th position in the depth position sequence, record the current position coordinates zᵢ, zᵢ = z0 +i·Δh, where zᵢ is the ultrasound probe position corresponding to the i-th step and i is the step number;

[0102] After completing the step-by-step control, h s , Δh, v s f s The position sequence zᵢ is stored as scan control data.

[0103] This invention introduces a control device consisting of a signal processing unit, a computing unit, and an output interface unit in terms of scanning parameter setting and step control execution. First, the scanning start position, step interval, scanning speed, and sampling frequency are set, and the initial coordinates of the ultrasound probe are determined. Then, the computing unit generates a control command sequence containing step distance and timing, and drives the motor step by step through the output interface unit, so that the ultrasound probe reaches the depth position sequence in sequence along the inclined direction of the closed duct and records the position coordinate sequence. In this way, scanning control data that is consistent with the time reference, consistent with the spatial step distance, and traceable is obtained.

[0104] In this embodiment, the ultrasonic emission, echo acquisition, and Doppler frequency shift calculation specifically include:

[0105] The control device calls the sampling frequency parameters, sets the pulse repetition frequency, time gating start time and time gating width, and generates transmit control commands and receive control commands.

[0106] Ultrasonic transmission is triggered at each predetermined depth position, and the receiving end collects the echo signal according to the sampling frequency to generate the echo data segment corresponding to the depth position;

[0107] Extract the echo envelope amplitude within the time-gated interval and record it as the echo intensity; extract the envelope arrival time and record it as the echo delay.

[0108] The Doppler frequency shift is calculated based on the echo signals generated by two adjacent transmissions. The phase difference of the main frequency components of the two adjacent echoes is multiplied by the pulse repetition frequency and then divided by twice pi to obtain the Doppler frequency shift value at the corresponding depth position.

[0109] A data frame is generated at each predetermined depth position. The data frame contains the depth position, echo intensity, echo delay, and Doppler frequency shift value.

[0110] Data frames are combined in depth order to form the original scan data.

[0111] This invention addresses ultrasonic transmission, echo acquisition, and Doppler shift calculation by setting pulse repetition frequency and time gating parameters and generating transmission and reception control commands. This enables controlled echo data segments to be generated at each predetermined depth position. The envelope amplitude and arrival time are then extracted within the gating interval and recorded as echo intensity and echo delay. Simultaneously, the Doppler shift value is calculated by converting the phase difference between the dominant frequency components of two adjacent echoes with the pulse repetition frequency. Finally, the data is combined in depth order to form raw scan data containing depth position, echo intensity, echo delay, and Doppler shift value.

[0112] In this embodiment, the identification of the water surface and silt interface and the calculation of the stratification rate specifically include:

[0113] Read the data frames from the original scan data in depth order. The data frames contain depth position, echo intensity, echo delay and Doppler frequency shift value.

[0114] Within the time-gated interval at each predetermined depth position, locate the peak time of the water surface echo and determine the water surface echo delay; locate the peak time of the silt interface echo and determine the silt interface echo delay.

[0115] The one-way distance from the probe to the water surface and the one-way distance from the probe to the silt interface are calculated based on the correspondence between the sound velocity of the medium and the echo delay. The one-way distance is expressed as half of the product of the sound velocity and the echo delay.

[0116] The water surface coordinates are obtained by adding the depth position to the one-way distance from the probe to the water surface, and the mud interface coordinates are obtained by adding the depth position to the one-way distance from the probe to the mud interface.

[0117] The stratified flow velocity components are calculated based on the Doppler frequency shift value and the velocity conversion factor, which is determined by the speed of sound, the transmission carrier frequency, and the incident angle.

[0118] A record entry is generated at each predetermined depth location. The record entry includes the depth location, water surface location coordinates, silt interface location coordinates, stratified flow velocity components, and echo intensity.

[0119] Record entries are grouped in depth order to form a hierarchical dataset.

[0120] This invention uses raw scanning data as input for water surface and silt interface identification and stratification velocity calculation. It locates the peak echo times of the water surface and silt interface according to depth order and calculates the one-way distance from the probe to the water surface and the probe to the silt interface based on this. The depth position is added to the corresponding one-way distance to obtain the coordinates of the water surface position and the silt interface position. The stratified flow velocity components are obtained based on the Doppler frequency shift value and the velocity conversion coefficient determined by the sound speed, the transmission carrier frequency and the incident angle. Thus, a stratified dataset containing the depth position, water surface position, silt interface position and stratified flow velocity components is formed.

[0121] In this embodiment, the construction of the cross-sectional tomography model and the calculation of the effective flow cross-sectional area and the average flow velocity of each layer specifically include:

[0122] Read the layered dataset and organize the depth position sequence, water surface position coordinate sequence, silt interface position coordinate sequence, and layered velocity component sequence according to the location of the closed conduit.

[0123] Interpolation and fitting are performed on the water surface position coordinate sequence and the silt interface position coordinate sequence in the depth direction of each closed conduit to generate a continuous interface trajectory in the depth direction.

[0124] Interpolation and fitting of the continuous interface trajectory according to the location of the closed conduit are performed to generate the water surface profile curve and the silt interface profile curve in the river cross-section tomography model.

[0125] Divide the layers into intervals according to the depth direction, determine the upper and lower boundary positions and the lateral sampling position sequence of each interval, and give the upper and lower boundary positions by the coordinates of the water surface profile curve and the silt interface profile curve at the corresponding depth.

[0126] Calculate the effective flow cross-sectional area within each layered interval. According to the lateral order of the closed conduit positions, multiply the distance between the water surface position coordinates and the silt interface position coordinates at the corresponding positions by the distance between adjacent closed conduit positions and then sum them up to obtain the effective flow cross-sectional area of ​​the current layered interval.

[0127] Calculate the average flow velocity within each layer interval, and perform a weighted average of the layer velocity components according to the location of the closed conduit. The weighting weight is the distance between the coordinates of the water surface and the coordinates of the silt interface at the corresponding location.

[0128] The water surface profile curve, the silt interface profile curve, the effective cross-sectional area of ​​each layer, and the average flow velocity of each layer are compiled into a river cross-sectional tomography model dataset.

[0129] In terms of constructing cross-sectional tomography models and calculating effective flow cross-sectional area and stratified average flow velocity, this invention interpolates and fits the stratified dataset according to the location of closed conduits to obtain continuous water surface profile curves and silt interface profile curves. Then, it divides the stratified intervals according to the depth direction and determines the upper and lower boundaries and the lateral sampling position sequence. Subsequently, within each stratified interval, the effective flow cross-sectional area is obtained by accumulating the water depth between the upper and lower boundaries and the distance between adjacent closed conduit positions point by point. Finally, the stratified flow velocity components are weighted according to the lateral position with water depth as the weight to obtain the stratified average flow velocity. Finally, the data is organized into a river channel cross-sectional tomography model dataset.

[0130] In this embodiment, the generation of total flow and real-time flow data for the stratified integral calculation section specifically includes:

[0131] The effective cross-sectional area and average velocity of each layer in the river cross-section tomography model dataset are used as calculation parameters.

[0132] The instantaneous flow rate of each layer is calculated by multiplying the effective cross-sectional area by the average velocity of the layer.

[0133] The total cross-sectional flow is obtained by summing the instantaneous flow rates of all layers at the same calculation time.

[0134] Record the correspondence between the calculation time and the total flow rate of the cross section, and generate real-time flow data records;

[0135] Real-time traffic data is compiled and recorded in chronological order to form real-time traffic data.

[0136] In terms of generating total cross-sectional flow and real-time flow data through layered integral calculation, this invention uses the effective cross-sectional area and average velocity of each layer in the river cross-sectional tomography model dataset as calculation parameters. The effective cross-sectional area of ​​each layer is multiplied by the corresponding average velocity to obtain the instantaneous flow of each layer, and these are added together at the same calculation time to obtain the total cross-sectional flow. At the same time, the correspondence between the calculation time and the total cross-sectional flow is recorded to form a real-time flow data record, which is then collected in chronological order to form continuous real-time flow data for scheduling and monitoring.

[0137] In this embodiment, the signal quality monitoring and self-cleaning linkage control specifically includes:

[0138] Signal monitoring parameters are set in the control device, including the lower limit of echo intensity, the upper limit of echo attenuation ratio, the upper limit of drive motor current, the upper limit of position error, the monitoring window duration, the spraying duration, and the number of wiping cycles.

[0139] During the scanning process, the echo intensity, echo attenuation ratio, drive motor current and position error are recorded according to the depth position, and the duration of each record within the monitoring window is calculated.

[0140] When the echo intensity is lower than the lower limit of echo intensity and the echo attenuation ratio is higher than the upper limit of echo attenuation ratio, and the duration is not less than the monitoring window duration, it is determined to be an ultrasonic signal attenuation event.

[0141] When the drive motor current is higher than the upper limit of the drive motor current and the position error is higher than the upper limit of the position error, and the duration is not less than the monitoring window duration, it is determined to be a closed conduit blockage event;

[0142] To handle ultrasonic signal attenuation events, a self-cleaning process is executed. The control device issues a self-cleaning command and starts the self-cleaning component to complete the spraying and wiping stages. The spraying stage runs according to the spraying duration, and the wiping stage runs according to the number of wiping cycles.

[0143] For closed conduit blockage events, a self-cleaning process is executed. The control device issues a self-cleaning command and starts the self-cleaning component to complete the spray washing stage and the wiping stage. The spray washing stage runs according to the spray washing duration, and the wiping stage runs according to the number of wiping repetitions.

[0144] After the self-cleaning process is completed, the cleaning timestamp and cumulative cleaning count are recorded, scanning control is restored, and parameter monitoring continues.

[0145] This invention sets a lower limit for echo intensity, an upper limit for echo attenuation ratio, an upper limit for drive motor current, and an upper limit for position error in signal quality monitoring and self-cleaning linkage control, and makes judgments in conjunction with the monitoring window duration. During the scanning process, various indicators are continuously recorded and the duration is counted. When the echo intensity and echo attenuation ratio meet the attenuation event condition or the drive motor current and position error meet the blocking event condition, the control device issues a self-cleaning command to start the self-cleaning component to complete the spraying and wiping, and records the timestamp and the cumulative number of cleanings to maintain channel cleanliness and echo stability in online operation.

[0146] Example 1:

[0147] To verify the feasibility of this invention in practice, it was applied to a test section of a river. The riverbed was mainly composed of fine sand, the channel width was about 20 meters, and the normal water depth was in the range of two to three meters. The flow velocity distribution was significantly non-uniform due to the influence of bank slope morphology and local backflow. During the test, the upstream discharge was artificially adjusted to form a slow rise and fall process, and a controllable concentration of sediment was added to the water to simulate siltation evolution. The goal was to obtain the total cross-sectional flow rate online for a long period of time under the dynamic changes of water level and silt interface, and to verify the effectiveness of the layered integral approach and the self-cleaning linkage strategy.

[0148] Six evenly distributed closed guide tubes were deployed on-site, with their axes inclined at 20 degrees relative to the water flow cross-section. The upper ends of the tubes extended above the water surface, connecting to the control device and motor drive mechanism, while the lower ends were buried in the riverbed to form a stable guide channel. An ultrasonic probe slider assembly was installed inside the tube and connected to a lead screw drive. The control device set the scanning start position, step interval, scanning speed, and sampling frequency, driving the ultrasonic probe to move layer by layer along the inclined direction of the tube. Transmission and reception were triggered at each depth position, and echo intensity, echo delay, and Doppler frequency shift were collected to form raw scan data. Subsequently, the upper boundary of the water body and the silt interface were identified based on the echo delay. The system calculates the velocity components at the corresponding depth based on Doppler frequency shift, generating a layered dataset containing depth coordinates, water surface position, silt interface position, and layer velocity. Then, it performs interpolation and fitting on the layered dataset to construct a river cross-section tomography model. Based on the coordinates of the water surface and silt interface, it determines the effective cross-sectional area and average velocity of each layer, and calculates the total flow rate of the cross-section by layer integration. During the scanning process, the control device monitors the echo intensity, echo attenuation ratio, drive motor current, and position error. When the indicators exceed the threshold, the self-cleaning component is activated to perform spraying and wiping until the channel is clear and the echo is stable.

[0149] During continuous operation, the step interval was set to 10 cm, the scanning speed to 25 cm / s, and the sampling frequency to 40 kHz. A single complete upward scan of a single duct took approximately 35 seconds. The cross-sectional synthesis cycle of six ducts was approximately 4 minutes. During the flooding phase, the average water depth increased from 2.1 m to 2.8 m. The silt interface experienced a short-term rise of 0.3 to 0.5 m at the center of the main channel. The root mean square error of the water surface position and the silt interface position, determined by echo delay, was within 3 cm when compared with the rod and the sampling profile. The relative error of the stratification velocity was within 3 to 5 percentage points when compared with the synchronous profile of the mobile acoustic Doppler profiler. The average relative error of the total cross-sectional flow obtained by stratification integration under different operating conditions was 100 to 200 points. The data availability rate reached 96 percentage points during 720 hours of continuous operation. The missing window was mainly caused by enhanced surface scattering due to short-term strong winds and waves and slight adhesion at the duct openings twice. Scanning resumed within 10 minutes after self-cleaning was triggered.

[0150] During the high sand content stage, the lower limit of echo intensity was set to 40% of the baseline, the upper limit of echo attenuation ratio was 2.5, the upper limit of drive motor current was 1.4 times the rated value, the upper limit of position error was 2 mm, the monitoring window duration was 30 seconds, and self-cleaning was triggered 32 times during three consecutive weeks, of which 70% were triggered by adhesion. The spraying stage lasted 30 seconds, and the wiping stage was repeated three times. After cleaning, the echo intensity recovered to more than 80% of the baseline and the position error returned to within 1 mm. The proportion of duct blockage completely relieved reached 100%. No cumulative displacement drift caused by cleaning action was found. The cumulative cleaning time recorded by the control device accounted for 0.6% of the total running time and did not affect the cross-sectional synthesis cycle.

[0151] To visually demonstrate the improvements of this invention in measurement accuracy, continuity, and maintenance burden, a fixed ultrasonic array method and a mobile acoustic Doppler profiler under the same cross-section and operating conditions were selected as comparative baselines. The fixed ultrasonic array method uses multiple fixed probes for layered sampling on the shore, while the mobile acoustic Doppler profiler completes a single profile measurement by slow manual lateral movement. All three methods use a unified reference flow rate for dual control calibration using gate operating conditions and volumetric methods. Key indicators are given in Table 1.

[0152] Table 1 Comparison of Online Flow Measurement Performance of Chromatographic Flowmeters

[0153] index This invention relates to a chromatographic flowmeter method based on ultrasonic scanning. Fixed ultrasound array method Mobile Acoustic Doppler Profiler Average relative error of total cross-sectional flow (compared to reference) 1.6% 3.8% 2.4% Stratified velocity average relative error 3.9% 6.2% 3.1% Root mean square error of water surface location 0.03 m 0.07 m 0.04 m Root mean square error of silt interface positioning 0.03 m 0.09 m 0.05 m Data availability (continuous operation phase) 96% 82% 35% Installation and alignment initial time 18 working hours 52 working hours 14 working hours Number of sensors (total number of cross sections) 6 movable probes 24 fixed probes 1 mobile platform Typical time for synthesizing a cross-section 4 min 1 min 12 min Self-cleaning trigger count (720 h) 32 times Not available not applicable Time to recover to stable echo after cleaning ≤10 min Not available not applicable Maintenance intervention frequency (720 h) 2 times 11 times 9 times

[0154] The comparative results show that under the same cross-sectional deformation background, the present invention obtains a unified dataset of water surface position, silt interface position and stratification velocity by single-probe step scanning and acoustic analysis in a closed duct. Then, the effective flow cross-sectional area is determined by cross-sectional tomography model and stratified integration is performed. This can achieve more stable total flow accuracy and higher data availability under conditions of fewer sensors and lower maintenance frequency. At the same time, the self-cleaning strategy, based on threshold judgment of echo intensity, echo attenuation ratio, drive motor current and position error, effectively ensures long-term continuous operation in high sand and adhesion scenarios.

[0155] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A chromatographic flowmeter method based on ultrasonic scanning, characterized in that, Includes the following steps: Closed conduits are installed evenly at different locations in the river channel. An ultrasonic probe that can move along the direction of the conduit is installed inside the closed conduit. The ultrasonic probe achieves controlled scanning along the tilt direction of the conduit through a motor-driven mechanism. The scanning start position, step interval, scanning speed and sampling frequency are set in the control device, and the ultrasound probe is driven to move layer by layer in the closed duct. During the scanning process, ultrasound signals are transmitted and received at various depth positions, and data on echo intensity, echo delay, and Doppler frequency shift are collected to form raw scan data; Acoustic analysis is performed on the raw scan data. The upper boundary of the water body and the bottom silt interface are identified based on the echo delay. The flow velocity component at the corresponding depth is calculated based on the Doppler frequency shift, generating a layered dataset containing information on depth, water surface position, silt interface position and flow velocity. Interpolation and fitting operations were performed on the stratified dataset to construct a river cross-section tomography model. The effective cross-sectional area and average velocity of each stratum were determined based on the spatial location of the water surface and the silt interface. Based on the effective cross-sectional area and average velocity of each layer, perform layered integral calculations to obtain the total flow of the river section and generate real-time flow data. If ultrasound signal attenuation or blockage of the closure catheter is detected during scanning or operation, the self-cleaning component is activated to clean the closure catheter and ultrasound probe.

2. The method for a chromatographic flowmeter based on ultrasonic scanning according to claim 1, characterized in that, The specific details of the closed conduit layout and the inclined stepping scanning mechanism include: Closed conduits are evenly distributed and installed at different locations in the river channel. Each closed conduit is fixed to the bank or river sidewall by a mounting bracket. The axial direction of the closed conduit forms an inclination angle θ with the water flow cross section, and the value of θ ranges from 15° to 30°. The upper end of the closed conduit extends out of the water surface to connect the control device and the motor drive mechanism. The lower end of the closed conduit is buried in the riverbed at a depth of h0, where h0 is the vertical distance from the bottom of the conduit to the riverbed reference surface. A sliding guide rail is installed along the length of the closed catheter, with the center line of the sliding guide rail parallel to the axis of the closed catheter, to limit the movement path of the ultrasound probe; A motor drive mechanism is installed at the upper end of the closed catheter. The motor output shaft is connected to a lead screw or rack and pinion transmission assembly. The lead screw pitch is denoted as p. It is used to drive the ultrasound probe to move stepwise along the inclined direction of the closed catheter. An ultrasonic probe slider assembly is installed inside a closed conduit. The slider assembly is connected to a lead screw nut, and the ultrasonic probe is fixed at the front end of the slider. The emitting surface of the ultrasonic probe is perpendicular to the axis of the closed conduit. Set the range of motion H of the ultrasonic probe. H is determined by the water surface position h1 and the bottom position of the conduit h0. H = h1 − h0, where h1 is the vertical height of the water surface corresponding to the upper end of the closed conduit. Signal and power lines are laid out on the outer wall of the sealed catheter to connect the signal output end of the ultrasound probe to the input end of the control device, thereby achieving synchronous execution of scanning control and data acquisition.

3. The method for a chromatographic flowmeter based on ultrasonic scanning according to claim 1, characterized in that, The scanning parameter setting and step control execution specifically include: Set the scan start position h in the control device. s Step interval Δh, scan speed v s and sampling frequency f s ; The control device consists of a signal processing unit, a calculation unit, and an output interface unit. The signal processing unit receives parameter input signals, the calculation unit generates a sequence of control commands, and the output interface unit sends control signals to the motor drive mechanism. Based on the scan start position h s Determine the initial position z0 of the ultrasonic probe inside the closed catheter, where z0 is the vertical coordinate of the ultrasonic probe's emitting surface relative to the bottom of the closed catheter; The arithmetic unit operates according to the step interval Δh and the scan speed v s Arrange the sequence of control instructions, which includes each step and its corresponding execution timing; The output interface unit outputs step-by-step control signals to the motor drive mechanism, driving the ultrasound probe to move sequentially to the depth position sequence along the inclined direction of the closed duct. After the ultrasound probe reaches the i-th position in the depth position sequence, record the current position coordinates zᵢ, zᵢ = z0 + i·Δh, where zᵢ is the ultrasound probe position corresponding to the i-th step and i is the step number; After completing the step-by-step control, h s , Δh, v s f s The position sequence zᵢ is stored as scan control data.

4. The method for a chromatographic flowmeter based on ultrasonic scanning according to claim 1, characterized in that, The ultrasonic emission, echo acquisition, and Doppler frequency shift calculation specifically include: The control device calls the sampling frequency parameters, sets the pulse repetition frequency, time gating start time and time gating width, and generates transmit control commands and receive control commands. Ultrasonic transmission is triggered at each predetermined depth position, and the receiving end collects the echo signal according to the sampling frequency to generate the echo data segment corresponding to the depth position; Extract the echo envelope amplitude within the time-gated interval and record it as the echo intensity; extract the envelope arrival time and record it as the echo delay. The Doppler frequency shift is calculated based on the echo signals generated by two adjacent transmissions. The phase difference of the main frequency components of the two adjacent echoes is multiplied by the pulse repetition frequency and then divided by twice pi to obtain the Doppler frequency shift value at the corresponding depth position. A data frame is generated at each predetermined depth position. The data frame contains the depth position, echo intensity, echo delay, and Doppler frequency shift value. Data frames are combined in depth order to form the original scan data.

5. The method for a chromatographic flowmeter based on ultrasonic scanning according to claim 1, characterized in that, The identification of the water surface and silt interface and the calculation of the stratification rate specifically include: Read the data frames from the original scan data in depth order. The data frames contain depth position, echo intensity, echo delay and Doppler frequency shift value. Within the time-gated interval at each predetermined depth position, locate the peak time of the water surface echo and determine the water surface echo delay; locate the peak time of the silt interface echo and determine the silt interface echo delay. The one-way distance from the probe to the water surface and the one-way distance from the probe to the silt interface are calculated based on the correspondence between the sound velocity of the medium and the echo delay. The one-way distance is expressed as half of the product of the sound velocity and the echo delay. The water surface coordinates are obtained by adding the depth position to the one-way distance from the probe to the water surface, and the mud interface coordinates are obtained by adding the depth position to the one-way distance from the probe to the mud interface. The stratified flow velocity components are calculated based on the Doppler frequency shift value and the velocity conversion factor, which is determined by the speed of sound, the transmission carrier frequency, and the incident angle. A record entry is generated at each predetermined depth location. The record entry includes the depth location, water surface location coordinates, silt interface location coordinates, stratified flow velocity components, and echo intensity. Record entries are grouped in depth order to form a hierarchical dataset.

6. The method for a chromatographic flowmeter based on ultrasonic scanning according to claim 1, characterized in that, The construction of the cross-sectional tomography model and the calculation of the effective flow cross-sectional area and the stratified average flow velocity specifically include: Read the layered dataset and organize the depth position sequence, water surface position coordinate sequence, silt interface position coordinate sequence, and layered velocity component sequence according to the location of the closed conduit. Interpolation and fitting are performed on the water surface position coordinate sequence and the silt interface position coordinate sequence in the depth direction of each closed conduit to generate a continuous interface trajectory in the depth direction. Interpolation and fitting of the continuous interface trajectory according to the location of the closed conduit are performed to generate the water surface profile curve and the silt interface profile curve in the river cross-section tomography model. Divide the layers into intervals according to the depth direction, determine the upper and lower boundary positions and the lateral sampling position sequence of each interval, and give the upper and lower boundary positions by the coordinates of the water surface profile curve and the silt interface profile curve at the corresponding depth. Calculate the effective flow cross-sectional area within each layered interval. According to the lateral order of the closed conduit positions, multiply the distance between the water surface position coordinates and the silt interface position coordinates at the corresponding positions by the distance between adjacent closed conduit positions and then sum them up to obtain the effective flow cross-sectional area of ​​the current layered interval. Calculate the average flow velocity within each layer interval, and perform a weighted average of the layer velocity components according to the location of the closed conduit. The weighting weight is the distance between the coordinates of the water surface and the coordinates of the silt interface at the corresponding location. The water surface profile curve, the silt interface profile curve, the effective cross-sectional area of ​​each layer, and the average flow velocity of each layer are compiled into a river cross-sectional tomography model dataset.

7. The method for a chromatographic flowmeter based on ultrasonic scanning according to claim 1, characterized in that, The generation of total flow and real-time flow data for the hierarchical integral calculation section specifically includes: The effective cross-sectional area and average velocity of each layer in the river cross-section tomography model dataset are used as calculation parameters. The instantaneous flow rate of each layer is calculated by multiplying the effective cross-sectional area by the average velocity of the layer. The total cross-sectional flow is obtained by summing the instantaneous flow rates of all layers at the same calculation time. Record the correspondence between the calculation time and the total flow rate of the cross section, and generate real-time flow data records; Real-time traffic data is compiled and recorded in chronological order to form real-time traffic data.

8. The method for a chromatographic flowmeter based on ultrasonic scanning according to claim 1, characterized in that, The signal quality monitoring and self-cleaning linkage control specifically includes: Signal monitoring parameters are set in the control device, including the lower limit of echo intensity, the upper limit of echo attenuation ratio, the upper limit of drive motor current, the upper limit of position error, the monitoring window duration, the spraying duration, and the number of wiping cycles. During the scanning process, the echo intensity, echo attenuation ratio, drive motor current and position error are recorded according to the depth position, and the duration of each record within the monitoring window is calculated. When the echo intensity is lower than the lower limit of echo intensity and the echo attenuation ratio is higher than the upper limit of echo attenuation ratio, and the duration is not less than the monitoring window duration, it is determined to be an ultrasonic signal attenuation event. When the drive motor current is higher than the upper limit of the drive motor current and the position error is higher than the upper limit of the position error, and the duration is not less than the monitoring window duration, it is determined to be a closed conduit blockage event; To handle ultrasonic signal attenuation events, a self-cleaning process is executed. The control device issues a self-cleaning command and starts the self-cleaning component to complete the spraying and wiping stages. The spraying stage runs according to the spraying duration, and the wiping stage runs according to the number of wiping cycles. For closed conduit blockage events, a self-cleaning process is executed. The control device issues a self-cleaning command and starts the self-cleaning component to complete the spray washing stage and the wiping stage. The spray washing stage runs according to the spray washing duration, and the wiping stage runs according to the number of wiping repetitions. After the self-cleaning process is completed, the cleaning timestamp and cumulative cleaning count are recorded, scanning control is restored, and parameter monitoring continues.

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