Flow calculation method, device and storage medium of multi-path ultrasonic flowmeter

Abstract

The application discloses a flow calculation method of a multi-path ultrasonic flowmeter, and aims at the fixed weight function flow integral method of a traditional multi-path time difference method ultrasonic flowmeter, which cannot meet the flow measurement accuracy under chaotic flow states caused by complex and changeable operation conditions of large pump stations. j and average flow velocities v at different heights ji , the average flow velocities v at different heights under typical operation conditions are established ji -flow Q j database, the flow values of the typical operation conditions are weighted and integrated based on the correlation analysis of the measured average flow velocities and the average flow velocities at the relative heights of the typical operation conditions, the flow value of the measured operation condition is obtained, and therefore the measurement accuracy of the flow integral algorithm of the multi-path time difference method ultrasonic flowmeter under extreme operation conditions of large pump stations is improved.

Description

Technical Field

[0001] This invention relates to the field of ultrasonic flow meter flow measurement technology, and specifically to a flow calculation method, device and storage medium for a multi-path acoustic flow meter. Technical Background

[0002] Real-time flow rates of each unit in a large pumping station are crucial for water usage scheduling decisions. Among the various flow measurement methods currently available for large pumping stations, multi-channel ultrasonic flow meters are increasingly being used for real-time flow measurement due to their advantages such as non-contact operation and wide measurement range. Currently, most major pumping stations employ multi-channel time-of-flight ultrasonic flow meters arranged at the inlet rectangular contraction section for real-time flow measurement.

[0003] Time-of-flight flowmeters essentially vector-superimpose the ultrasonic wave propagation velocity with the fluid velocity, relying on the time difference between the upstream and downstream propagation of the ultrasonic waves to reflect the flow velocity. However, single-channel ultrasonic flowmeters are easily affected by velocity distribution and cannot fully reflect the actual flow field within the pipe. Therefore, for large pumping stations with diverse operating conditions and complex flow regimes, it is currently necessary to arrange multiple pairs of ultrasonic transducers inside the flow channel, uniformly dividing the flow cross-section into several flow layers. The average velocity of each flow layer is determined by the average velocity of the acoustic path within that layer, and then the flow rate is calculated using a flow integral method based on the Gauss-Legendard integral.

[0004] Existing ultrasonic flow meter flow integration methods share a common problem: the preset average velocity distribution along the sound channels is fixed and does not change with the flow state. In actual extreme conditions, the flow pattern distribution in the channels is highly chaotic, and existing integration methods cannot accurately identify adverse flow patterns such as backflow and vortices, leading to a significant reduction in the measurement accuracy of ultrasonic flow meters. In the actual operation of large pumping stations, it has been found that under extreme conditions, the maximum reading error of ultrasonic flow meters using the cross-channel multi-path time-of-flight method can reach 30%, making it impossible to accurately determine the real-time flow rate of the pumping station under extreme conditions. This flow error directly affects the rationality of scheduling decisions at all levels. Furthermore, since the ultrasonic transducer within the ultrasonic flow meter is a pre-embedded device in the pumping station, once the pumping station is built, it is impossible to improve the measurement accuracy of the ultrasonic flow meter under extreme conditions by increasing the number of sound paths.

[0005] Taking a single-channel time-difference flow meter as an example, its measurement principle is as follows: Figure 1 As shown, S is the straight-line distance of the ultrasonic flowmeter transducer, α is the angle between the flow channel axis and the acoustic path of the transducer, the speed of ultrasonic waves in a stationary fluid is c, the fluid velocity in the pipe to be measured is v, the downstream propagation time of ultrasonic waves is T1, and the upstream propagation time is T2. The calculation formula is as follows:

[0006]

[0007] For ultrasonic flow meters, the speed of ultrasonic waves in still water is approximately 1500 m / s. Based on the measurement range of the ultrasonic flow meter, it can generally be assumed that the flow velocity of the liquid being measured is much smaller than the propagation speed of ultrasonic waves. The formula for calculating the axial average velocity of the fluid at the measured flow cross-section is as follows:

[0008]

[0009] The formula Q = AV is used to calculate the flow rate, where A is the cross-sectional area of ​​the flow to be measured.

[0010] Single-channel ultrasonic flow meters are easily affected by velocity distribution and cannot fully reflect the actual flow field in the pipeline. For large pumping stations with multiple operating conditions and complex flow patterns, it is necessary to arrange multiple pairs of cross channels inside the flow channel to evenly divide the flow cross section into several flow layers. The average axial velocity of each flow layer is determined by the average velocity of the cross sound path within the flow layer.

[0011] The traditional method for integrating flow in rectangular pipes is the Gauss-Legendender integral, calculated using the following formula:

[0012]

[0013] In the formula, Q is the partial flow rate of the cross-sectional area to be measured, and w i For the integral weight of the i-th flow layer, t i v(t) represents the relative acoustic path height. i ) represents the axial average velocity relative to the acoustic path height, H represents the height of the cross-section to be measured, B represents the width of the cross-section to be measured, and n represents the number of flow layers.

[0014] According to Gaussian integral theory, when n is fixed, there exists an optimal set of w. i t i This ensures the highest integration accuracy.

[0015] The relative heights and corresponding weighting coefficients of each acoustic path in a multi-path ultrasonic flowmeter, obtained using the Gauss-Legendal integral algorithm, are fixed values. The calibration state is based on fully developed flow within a long, straight rectangular pipe and remains unchanged regardless of the flow conditions. However, for elbow-type inlet channels in large pumping stations, the magnitude and direction of the water flow velocity vary along the flow path, resulting in insufficient fluid development. Furthermore, under low water level and low flow conditions, adverse flow regimes such as backflow and flow deviation exist. Fixed weighting coefficients cannot adapt to all situations, thus reducing the measurement accuracy of the ultrasonic flowmeter under special operating conditions.

[0016] To address the aforementioned issues, the applicant has proposed a flow calculation method for cross-path ultrasonic flow meters (application number: 202411204230.X). This multi-path ultrasonic flow meter data fusion method, based on laminar velocity vector classification, can improve the measurement accuracy of existing ultrasonic flow meters in pumping stations. However, this method can only provide the optimal integration weights at a finite number of different heights, and there is still room for improvement. Summary of the Invention

[0017] The present invention aims to at least partially solve one of the technical problems in the related art.

[0018] Therefore, the purpose of this invention is to provide a flow calculation method, device, and storage medium for a multi-path ultrasonic flow meter, so as to obtain the average flow velocity of the acoustic path at all heights in the entire flow measurement section under different operating conditions without changing the installation position of the existing ultrasonic flow meter, thereby improving the measurement accuracy of the ultrasonic flow meter under the actual operating conditions of the pump station.

[0019] To achieve the above objectives, the present invention adopts the following technical solution:

[0020] The first aspect of this invention provides a method for calculating the flow rate of a multi-channel ultrasonic flow meter, comprising:

[0021] Step S1: Construct a model test platform for the pump station based on the inlet flow channel of the pump station to be tested. Each pump is equipped with a calibrated flow meter with a measurement accuracy higher than that of an ultrasonic flow meter on its corresponding outlet pipe. The flow channel section covered by the ultrasonic flow meter installed in a certain unit of the pump station is taken as the flow measurement section. A PIV test device is built around it to construct a three-dimensional rectangular coordinate system of the flow measurement section. Within the flow measurement section, a XY sections to be measured under different Z coordinates and b XZ sections to be measured under different Y coordinates are determined.

[0022] Step S2: Determine N typical operating conditions for the pump station under test, conduct bidirectional flow field PIV experiments on the inlet flow regime under each typical operating condition, and record the reading Q of the calibrated flowmeter under each typical operating condition. j Particle images of a XY section and b XZ section under various typical working conditions were collected using a PIV testing device. Based on the collected particle images, PIV calculations were performed to obtain the two-dimensional velocity vectors of each measurement section under different typical working conditions.

[0023] Step S3: Perform two-dimensional interpolation on the two-dimensional velocity vectors of each section to be measured under different typical working conditions to obtain the two-dimensional velocity field of the measuring section; introduce the continuity equation as a physical constraint to perform three-dimensional interpolation on the two-dimensional velocity field to realize the reconstruction of the three-dimensional flow field inside the measuring section under each typical working condition.

[0024] Step S4: Based on the reconstructed three-dimensional flow field inside the flow measurement section under each typical working condition, integrate the velocity information of each grid point at different heights under each typical working condition to obtain the average flow velocity v at the corresponding height i. ji Establish the average flow velocity v at different heights under typical working conditions. ji -Traffic Q j database;

[0025] Step S5: Under the actual operating conditions, perform a correlation analysis between the average sound velocity measured by all ultrasonic flow meters in the pumping station under test and the average flow velocity at different heights under each typical operating condition in the database. Select the average flow velocity and flow rate corresponding to the typical operating condition that is most relevant to the actual operating conditions as the basic data, and use the weighted integral method to calculate the flow rate value of the actual operating conditions.

[0026] In some embodiments, the pump station model test bench includes an elbow-shaped flow channel, a vertical axial flow pump, an outlet pipe, a connecting pipe, and a circulation pool connected in sequence to form a circulation loop. The elbow-shaped flow channel is made of transparent material, and tracer particles are added to the fluid in the circulation loop.

[0027] The PIV testing equipment includes a transparent water tank, a laser, and a single camera. The elbow-shaped flow channel is set inside the transparent water tank. Each determined test section is marked on the side wall of the transparent water tank to ensure that the plane of the laser generated by the laser coincides with the test section.

[0028] In some embodiments, step S2, when performing a two-dimensional PIV flow field measurement on any XY section to be measured under a typical working condition, includes:

[0029] Step S211: Adjust the position of the laser installed above the elbow-shaped flow channel so that the sheet light formed by the laser coincides with an XY section to be measured.

[0030] Step S212: Set up the camera on the side of the elbow-shaped flow channel, make the camera clearly image and ensure that the camera imaging plane is parallel to the XY section to be measured. With the laser off, place the checkerboard calibration plate at the XY section to be measured and take a checkerboard calibration image.

[0031] Step S213: Take a set of continuous XY cross-sectional particle images for the current XY cross-section to be tested;

[0032] Step S214: Average the continuous XY cross-sectional particle images to obtain an average particle image containing background information. Subtract the calculated average particle image containing background information from each particle image in the continuous XY cross-sectional particle images to obtain a continuous XY cross-sectional particle image with background light interference removed.

[0033] Step S215: Perform PIV calculation on the continuous XY cross-section particle image after removing background light interference to obtain the two-dimensional flow velocity vector of each node in the current XY cross-section under test in pixel units. Combined with the checkerboard calibration image taken in step S212, obtain the two-dimensional flow velocity vector (v, u) of each node in the current XY cross-section under test.

[0034] In some embodiments, in step S2, when performing PIV two-dimensional flow field measurement on any XZ section to be measured under a typical working condition, the imaging plane of the camera is made horizontal and has an angle with the XZ section to be measured. The particle image of the XZ section to be measured captured by the camera is corrected by perspective using the checkerboard calibration method. Based on the corrected particle image of the XZ section to be measured, the two-dimensional flow velocity vector (v, w) of each node in the XZ section to be measured is obtained.

[0035] In some embodiments, in step S3, when introducing a continuity equation as a physical constraint to perform three-dimensional interpolation on the two-dimensional velocity field, a target value for the change of the average velocity along the flow path on each YZ section of the elbow-shaped channel within the flow measurement section is defined. By minimizing the deviation between the adjusted velocity field and the initial three-dimensional interpolation result, the final reconstruction result is ensured to meet the physical constraint.

[0036] In some embodiments, in step S4, the average flow velocity v at the corresponding height i is obtained by integrating the velocity information of each grid point at different heights under each typical working condition according to the following formula. ji :

[0037]

[0038] In the formula, L i The length of the sound path at height i represents the length of the sound path at height i. The three-dimensional flow field inside the reconstructed flow measurement section contains n heights, where i takes the values ​​1, 2, ..., n. ds represents the three-dimensional velocity vector inside the flow measurement section under the j-th typical working condition of the reconstruction; ds represents the linear infinitesimal vector along the integration path.

[0039] v ji By correspondingly mapping the flow rate measured by the calibrated flow meter under the corresponding operating conditions, the average flow velocity v at different heights under the typical operating conditions is obtained. ji -Traffic Q j database.

[0040] In some embodiments, in step S5, the average sound velocity measured by the n' ultrasonic flowmeters in the pumping station under test under actual operating conditions is calculated using the following formula. The average flow velocity v at different heights under the j-th typical working condition in the database ji Correlation analysis was performed to obtain the correlation coefficient s. j :

[0041]

[0042] In the formula, i is the acoustic path number of the ultrasonic flowmeter in the pumping station to be tested; v is the average sound velocity for the j-th typical working condition in the database; i' The average flow velocity is measured by the i'th ultrasonic flow meter.

[0043] In some embodiments, step S5, selecting the average flow velocity and flow rate corresponding to the typical operating condition most relevant to the measured operating condition as basic data, and calculating the flow rate value of the measured operating condition using a weighted integral method, includes:

[0044] After obtaining N correlation coefficients, the average flow velocity and flow rate corresponding to the n' typical operating conditions with the highest correlation to the measured operating conditions are selected as the basic data. Finally, the flow rate value Q of the measured operating condition is determined by the Q values ​​corresponding to the selected n' typical operating conditions. k and v ki' The weighted interpolation yields:

[0045]

[0046] In the formula, Q k w represents the flow rate corresponding to the k-th typical operating condition in the selected basic data. ki' λ represents the contribution of the flow rate of the i'th acoustic path to the total flow rate under the k-th typical operating condition in the selected basic data. ki' The average flow velocity measured by the i'th ultrasonic flow meter represents the ratio of the average flow velocity of the i'th ultrasonic path under the kth typical operating condition in the selected basic data; A represents the cross-sectional area of ​​the flow path.

[0047] A second aspect of the present invention provides a flow calculation device for a multi-channel ultrasonic flow meter, comprising:

[0048] The database storage module is used to store the average flow velocity v at different heights under the typical operating conditions established in the flow calculation method according to any embodiment of the first aspect of the present invention. ji -Traffic Q j database;

[0049] The calculation module is used to perform correlation analysis between the average sound velocity measured by all ultrasonic flowmeters in the pumping station under test and the average flow velocity at different heights under various typical conditions in the database under actual test conditions. The average flow velocity and flow rate corresponding to the typical test condition that is most similar to the actual test condition are selected as the basic data, and the flow rate value under the actual test condition is calculated by weighted integral method.

[0050] A third aspect of the present invention provides a computer-readable storage medium storing computer instructions for causing the computer to perform a flow calculation method according to any embodiment of the first aspect of the present invention.

[0051] Compared with the prior art, the present invention has the following characteristics and beneficial effects:

[0052] This invention addresses the problems encountered by multi-path ultrasonic flowmeters in flow measurement at pumping stations. Taking the most common variable rectangular contracting elbow-shaped flow channel in large pumping stations as an example, it proposes a flow calculation method for multi-path ultrasonic flowmeters based on flow space. By constructing a pumping station model experimental platform, a two-dimensional PIV experiment was conducted to observe the inlet flow pattern of the variable rectangular contracting elbow-shaped flow channel. Combined with a three-dimensional reconstruction method, the full three-dimensional flow field information of the ultrasonic measurement section within the elbow-shaped flow channel under different operating conditions, and the corresponding flow rate Q, were obtained. j and the average flow velocity v of the sound channel lines at several different heights j-i Based on this, the average velocity distribution v of the sound channel under typical operating conditions was established. j-i -Traffic Q j Database. The average velocity v of a finite number of acoustic channels measured by the ultrasonic transducer under the test condition is used. i Similarity analysis was performed on the velocity distributions of typical operating conditions in the database. The average velocity distributions and flow rates of k (k = 1, 2, ..., n) typical operating conditions most similar to the one under test were selected as the basis. A weighted integral method was used to calculate the flow rate value of the operating condition under test. Comparison with traditional flow integration methods showed that the multi-path ultrasonic flowmeter data integration method based on flow space can improve the accuracy of flow measurement without changing the existing ultrasonic transducer arrangement conditions of the pump station. Its core is to perform correlation analysis between the average velocity of a finite number of measured acoustic paths and the velocity of pre-stored typical operating conditions, and then use the obtained correlation coefficients as weights to perform a weighted integral on the flow rate of the typical operating conditions, ultimately obtaining the flow rate value of the measured operating condition. This invention features fast calculation speed, suitable for online monitoring; no complex fluid model is required; and by combining similarity weights with the integral method, extrapolation capability is improved, enabling the acquisition of acoustic path integral weights at different heights under different flow regime distributions in the same type of flow channel. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the existing flow meter measurement principle based on the monophonic time difference method;

[0054] Figure 2 This is an overall flowchart of a flow calculation method for a multi-channel ultrasonic flow meter provided in the first aspect embodiment of the present invention;

[0055] Figure 3 yes Figure 2A schematic diagram of the structure of the pump station model experimental platform built in the provided flow calculation method;

[0056] Figure 4 In the middle (a) and (b) respectively Figure 2 A schematic diagram of the xz and xy coordinates constructed in the provided flow calculation method;

[0057] Figure 5 yes Figure 2 A schematic diagram of the PIV test equipment set in the provided flow calculation method;

[0058] Figure 6 This is a schematic diagram of the structure of the electronic device provided in the third embodiment of the present invention;

[0059] In the picture:

[0060] 100. Pump station model test bench; 110. Elbow-shaped flow channel; 111. Inlet end; 112. Outlet end; 120. Vertical axial flow pump; 130. Water outlet pipe; 140. Connecting pipe; 150. Circulation pool; 160. Calibration flow meter; I. ​​Inlet section; II. Bend section; III. Outlet section;

[0061] 200. PIV testing equipment; 210. Transparent water tank; 220. Laser; 230. Camera. Detailed Implementation

[0062] To make the objectives, technical solutions, and advantages of this application clearer, the application will be described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application.

[0063] Conversely, this application covers any alternatives, modifications, equivalent methods, and schemes made within the spirit and scope of this application as defined by the claims. Furthermore, to provide the public with a better understanding of this application, certain specific details are described in detail below. However, this application can be fully understood by those skilled in the art even without these detailed descriptions.

[0064] See Figure 2 The first aspect of this invention provides a method for calculating the flow rate of a multi-channel ultrasonic flow meter, comprising the following steps:

[0065] Step S1: Construct a pump station model test bench based on the inlet flow channel of the pump station to be tested. Each pump is equipped with a calibrated flow meter with a measurement accuracy higher than that of an ultrasonic flow meter on its corresponding outlet pipe. The flow channel section covered by the ultrasonic flow meter installed on the side unit of the pump station is taken as the flow measurement section. A PIV test device is built around it to construct a three-dimensional rectangular coordinate system of the flow measurement section. Within the flow measurement section, a XY sections to be measured under different Z coordinates and b XZ sections to be measured under different Y coordinates are determined.

[0066] Step S2: Determine N typical operating conditions for the pump station under test, and conduct a bidirectional flow field PIV experiment on the inlet flow pattern under each typical operating condition. After the reading of the calibrated flowmeter stabilizes under each typical operating condition, record the reading Q of the calibrated flowmeter. j , j represents the j-th typical working condition. PIV test equipment is used to collect particle images of a XY sections and b XZ sections to be measured under each typical working condition. PIV is calculated based on the collected particle images to obtain the two-dimensional velocity vector of each measurement section under different typical working conditions.

[0067] Step S3: Perform two-dimensional interpolation on the two-dimensional velocity vectors of each section to be measured under different typical working conditions to obtain the two-dimensional velocity field of the measuring section; introduce the continuity equation as a physical constraint to perform three-dimensional interpolation on the two-dimensional velocity field to realize the reconstruction of the three-dimensional flow field inside the measuring section under different typical working conditions.

[0068] Step S4: Based on the reconstructed three-dimensional flow field inside the flow measurement section under each typical working condition, integrate the velocity information of each grid point at different heights under each typical working condition to obtain the average flow velocity v at the corresponding height i. ji Establish the average flow velocity v at different heights under typical working conditions. ji -Traffic Q j database;

[0069] Step S5: Under the actual operating conditions, perform correlation analysis between the average sound velocity measured by all ultrasonic flow meters in the pumping station under test and the average flow velocity at different heights under each typical operating condition in the database. Select the average flow velocity and flow rate corresponding to the typical operating condition most similar to the actual operating conditions as the basic data, and use the weighted integral method to calculate the flow rate value of the actual operating conditions.

[0070] In some embodiments, see Figure 3 and Figure 4(a) and (b) are schematic diagrams of the pump station model test bench constructed in step S1 of this embodiment of the invention. A large actual pump station using elbow-shaped channels as inlet channels is used as the test pump station. Based on the principle of hydraulic similarity, a pump station model test bench 100 is constructed to strictly reproduce the basic characteristics of elbow-shaped channels in actual engineering. In this embodiment, the test pump station has four parallel and symmetrically distributed elbow-shaped channels, sequentially labeled as elbow-shaped channels 1# to 4#. Elbow-shaped channels 1# and 4# are located on the sides. Compared to the middle elbow-shaped channels 2# and 3#, elbow-shaped channels 1# and 4# have more complex operating conditions. Due to their symmetrical distribution, only the inlet flow state PIV experiment can be conducted on elbow-shaped channel 1#, which can represent the distribution of the inlet flow state inside the elbow-shaped channel corresponding to the 4# side unit under symmetrical operating conditions. It should be noted that the relatively simple geometry of the elbow-shaped flow channel inlet section provides a relatively stable flow field and reliable acoustic wave propagation environment for the ultrasonic flow meter, while the complex flow characteristics of the curved section introduce significant errors. Therefore, the ultrasonic transducers are all installed in the inlet section of the elbow-shaped flow channel, and this invention only conducts PIV experiments on the inlet section of the elbow-shaped flow channel. The constructed pump station model test platform 100 includes an elbow-shaped flow channel 110, a vertical axial flow pump 120, an outlet pipe 130, a connecting pipe 140, and a circulation tank 150, which are connected in sequence to form a circulation loop. The elbow-shaped flow channel 110 is made of transparent material and is divided into an inlet section I, a curved section II, and an outlet section III along the direction of water flow. The outlet end 112 of the elbow-shaped flow channel 110 is connected to one end of the outlet pipe 130 via the vertical axial flow pump 120. The other end of the outlet pipe 130 is connected to the circulation tank 150 via the connecting pipe 140. A calibration flow meter (an electromagnetic flow meter is used in this embodiment) 160 is installed on the outlet pipe 130. The circulation tank 150 is connected to the inlet end 111 of the elbow-shaped flow channel 110. Tracer particles are added to the fluid in the connection and circulation loop. Let the width and height of the inlet end 111 of the elbow-shaped flow channel 110 be B and H, respectively. The inlet section I is taken as the flow measurement section and its three-dimensional rectangular coordinate system xyz is constructed. The direction parallel to the center line of the inlet section I of the elbow-shaped flow channel 110 is taken as the x-axis, and the direction in the direction of water flow is defined as the positive direction of the x-axis. The direction parallel to the width of the inlet end 111 of the elbow-shaped flow channel 110 is taken as the z-axis, and the direction perpendicular to the xz plane and upward along the water depth is taken as the positive direction of the y-axis. The origin of the coordinate system is located at the bottom of the inlet section I near the inlet end 111. The flow velocity in the main flow direction in the elbow-shaped flow channel 110 is defined as v, the flow velocity in the positive direction of the y-axis is defined as u, and the flow velocity in the positive direction of the z-axis is defined as w.

[0071] It is understood that the embodiments of the present invention are aimed at the elbow-shaped water inlet channel commonly found in large pumping stations. This channel is different from the traditional circular or square straight pipe. It is an irregular channel with variable rectangular contraction. It is necessary to construct a corresponding three-dimensional rectangular coordinate system based on its channel centerline and its main dimensions to determine the XY section and XZ section direction, which is convenient for subsequent PIV two-dimensional flow field calculation.

[0072] In some embodiments, see Figure 5 This is a schematic diagram of the PIV testing equipment 200. The PIV testing equipment 200 includes a transparent water tank 210, a laser 220, and a single camera 230. An elbow-shaped flow channel 110 is set inside the transparent water tank 210. The fluids inside the elbow-shaped flow channel 110 and the transparent water tank 210 are independent of each other. The laser 220 and the camera 230 are both mounted near the elbow-shaped flow channel 110. The acquisition frequency of the camera 230 is controlled by a synchronizer (not shown in the figure). Within the measurement section, a XY sections to be measured under different Z coordinates and b XZ sections to be measured under different Y coordinates are determined. The determined sections to be measured are marked on the side wall of the transparent water tank 210 to ensure that the plane of the laser generated by the laser 220 coincides with the section to be measured.

[0073] Furthermore, the laser 220 in the PIV testing equipment 200 is a sheet light source. The number of a and b is set according to the testing accuracy of PIV. In this embodiment, a test section is taken every 4cm within the inlet section I, with a total of 11 test XY sections and 5 test XZ sections.

[0074] In some embodiments, step S2 requires determining N typical operating conditions of the pumping station under test based on the normal and extreme operating conditions that cover the design operating parameter range (such as design flow rate, design head, and other key indicators for normal pumping station operation) and reflect the actual operating needs of the pumping station under test. A bidirectional flow field PIV experiment is then conducted under each typical operating condition. After the reading of the calibration flowmeter 160 on the outlet branch pipe corresponding to the pump connected to the flow measurement section stabilizes under each typical operating condition, the reading Q of the calibration flowmeter is recorded. j To ensure that the tracer particles of appropriate concentration are fully mixed in the experimental fluid, the laser 220 and camera 230 are turned on to acquire particle images of a measured XY cross sections and b measured XZ cross sections under various typical working conditions. Based on the acquired particle images, PIV calculation is performed to obtain the two-dimensional velocity vector of each node in each measurement cross section.

[0075] Furthermore, in step S2, the specific steps for conducting a bidirectional flow field PIV experiment on a typical operating condition include:

[0076] Step S21: Perform PIV flow field measurements on a XY cross sections:

[0077] Step S211: Adjust the position of the laser 220 installed above the elbow-shaped flow channel 110 so that the sheet light formed by the laser precisely coincides with an XY section to be measured.

[0078] Step S212: Adjust the position of the camera 230, which is placed on the side of the elbow-shaped flow channel 110 via a tripod, to ensure clear imaging and that the camera's imaging plane is parallel to the current XY section to be measured. With the laser 220 off, place a checkerboard calibration plate at the current XY section to be measured. Specifically, the checkerboard calibration plate can be inserted into the elbow-shaped flow channel 110 from the inlet end 111 and fixed at the corresponding XY section to be measured using a clamp. The corner points and dimensions of the checkerboard calibration plate are known. Take a picture of the checkerboard calibration and store it for subsequent pixel coordinate conversion.

[0079] Step S213: Connect camera 230 to a synchronizer. The synchronizer sends a signal to control camera 230 to continuously acquire a set of continuous XY cross-sectional particle images. Specifically, camera 230 continuously acquires two images of the current XY cross-section particle data, then pauses for one second. Each frame has a sampling duration of 0.002 seconds, and a single sampling duration is 1800 frames. The synchronizer can adjust camera 230 to acquire flow field data over a longer period during a single acquisition, thereby obtaining more accurate average flow field information.

[0080] Step S214: Use MATLAB software to average the 1800 consecutive XY cross-sectional particle images acquired in step S213 to obtain an average particle image containing background information. Then, subtract the calculated average particle image containing background information from each particle image in the set of consecutive XY cross-sectional particle images to effectively remove the interference of background light and obtain more accurate particle information.

[0081] Step S215: Perform PIV calculation on the continuous XY cross-sectional particle image after removing background light interference (in this embodiment, the existing PIV calculation software JFMeter can be used to perform PIV calculation), obtain the two-dimensional velocity vector of each node in the current XY cross-section under test in pixel units, and combine it with the checkerboard calibration image taken in step S212 to convert the pixel units into real units to obtain the two-dimensional velocity vector (v, u) of each node in the current XY cross-section under test in real units.

[0082] Step S216: For the remaining XY sections to be measured, repeat the operations of steps S211 to S215 to carry out PIV flow field measurements.

[0083] Step S22: Perform PIV flow field measurements on b XZ cross sections:

[0084] Step S221: Install the laser 220 on one side of the elbow-shaped flow channel 110, and adjust the position of the laser 220 so that the sheet light formed by the laser precisely coincides with an XZ section to be measured.

[0085] Step S222: Place the camera 230 above the elbow-shaped flow channel 110, adjust the position of the camera 230 to ensure clear imaging, and ensure that the imaging plane of the camera is horizontal. The optimal angle of the camera should be controlled to be parallel to the XZ section to be measured (the angle with the horizontal plane is the angle between the center line of the inlet section I of the elbow-shaped flow channel 110 and the horizontal plane). Since the outlet end 112 of the elbow-shaped flow channel 110 is connected to the vertical axial flow pump 120, the optimal conditions for camera installation are not met. Therefore, the camera 230 can only be controlled to be horizontal. Subsequently, perspective transformation correction is performed on the continuous images obtained by shooting to eliminate the distortion caused by the angle between the camera imaging plane and the section to be measured. With the laser 220 off, a checkerboard calibration plate is placed at the XZ section to be measured (the checkerboard calibration plate and its placement method are the same as in step S212), so that the camera 230 is at different shooting angles and shooting positions relative to the checkerboard calibration plate, and multiple checkerboard calibration images are stored for subsequent pixel coordinate transformation and perspective transformation correction of the images.

[0086] Step S223: Connect camera 230 to a synchronizer. The synchronizer sends a signal to control camera 230 to continuously acquire a set of continuous XZ cross-sectional particle images. Specifically, camera 230 continuously acquires two images of the current XZ cross-section particle data, then pauses for one second. Each frame has a sampling duration of 0.002 seconds, and a single sampling duration is 1800 frames. The synchronizer can adjust camera 230 to acquire flow field data over a longer period during a single acquisition, thereby obtaining more accurate average flow field information.

[0087] Step S224: Use the checkerboard calibration image to perform perspective transformation correction on the XZ section particle image:

[0088] Using existing corner detection image processing algorithms, the corner points of the checkerboard calibration plate in each checkerboard calibration image are detected. Camera calibration is performed using MATLAB, and the camera's intrinsic and extrinsic parameters are calculated. Four corner points are selected from the corresponding checkerboard calibration image, usually the four corner points of the checkerboard calibration plate, whose coordinates are known. The four corner points selected in the checkerboard calibration image are mapped to the three-dimensional rectangular coordinate system of the elbow-shaped flow channel inlet section. The perspective transformation matrix is ​​calculated using MATLAB. The calculated perspective transformation matrix is ​​applied to the captured continuous XZ cross-sectional particle images. Specifically, the pixel coordinates of the XZ cross-sectional particle images acquired in step S223 are multiplied by the above perspective transformation matrix to correct the distorted particle images to a new rectangular plane, thereby eliminating the distortion caused by the camera angle tilt, and obtaining a set of corrected continuous XZ cross-sectional particle images.

[0089] Step S225: Use MATLAB software to average a set of corrected continuous (1800 frames) XZ cross-sectional particle images to obtain an average image containing background information. Then, subtract the calculated average image containing background information from each image in this set of continuous XZ cross-sectional particle images to effectively remove the interference of background light and obtain more accurate particle information.

[0090] Step S226: Perform PIV calculation on the continuous XZ cross-section particle image after removing background light interference to obtain the two-dimensional velocity vector of each node in the current XZ cross-section under test in pixel units. Combined with the calibration image taken in step S222, convert the pixel units to real units to obtain the two-dimensional velocity vector (v, w) of each node in the current XZ cross-section under test in real units.

[0091] It is understandable that, considering the camera's imaging plane is horizontal when capturing the XZ cross-section, while the XZ cross-section under test is not horizontal, the two are not parallel, resulting in some distortion. This embodiment of the invention employs a checkerboard calibration method to perform perspective correction on the XZ cross-section particle images. Before acquiring XZ cross-section particle images at different Y coordinates, a pre-fabricated checkerboard is first fixed on the XZ cross-section under test at the corresponding Y coordinate, and the camera position is adjusted to ensure clear imaging. After capturing the checkerboard image at this point, the perspective transformation matrix is ​​calculated using MATLAB. While keeping the camera parameters unchanged, the checkerboard is removed, and a series of XZ cross-section particle images are captured at that Y coordinate. Finally, the calculated perspective transformation matrix is ​​used to perform perspective transformation on the particle images, thereby achieving geometric correction of the images.

[0092] In some embodiments, step S3 reconstructs the three-dimensional flow field inside the flow measurement section for a typical operating condition, specifically including:

[0093] Step S31: Perform two-dimensional interpolation on each point in the *a* XY sections to obtain the velocity information in the X and Y directions at the node to be measured; perform two-dimensional interpolation on each point in the *b* XZ sections to obtain the velocity information in the X and Z directions at the node to be measured. Since the known velocity information points within the sections obtained from the PIV experiment are sufficiently dense, the more common spline interpolation can be selected when performing two-dimensional interpolation on the XY and XZ sections to obtain the velocity information of the target grid points. Each measurement section lacks a third velocity component, for example, XY lacks w, and XZ lacks v, which needs to be supplemented in subsequent interpolation.

[0094] Step S32: Refine the 3D mesh composed of a XY sections and b XZ sections after interpolation to obtain 3D velocity information at unknown nodes, thus reconstructing the 3D flow field inside the elbow-shaped channel. Due to the additional flow complexity and disturbances besides the main flow inside the elbow-shaped channel, the flow field distribution is quite complex. Directly interpolating the velocity information on a XY sections and b XZ sections may produce significant errors. Therefore, a continuity equation needs to be introduced as a physical constraint during interpolation to optimize the missing velocity components at each target mesh point, obtaining the reconstructed 3D flow field inside the elbow-shaped channel. Specifically, a target value for the change of the average velocity along the flow path on each YZ section of the elbow-shaped channel within the measurement section should be defined. After the 3D interpolation is completed, further optimization is performed to minimize the deviation between the adjusted velocity field and the initial 3D interpolation result, thereby ensuring that the final reconstruction result meets the above physical constraints. The formula for calculating the continuity equation is as follows:

[0095]

[0096] Among them, v ' u ' w ' This represents the three-dimensional flow velocity that satisfies physical constraints.

[0097] In some embodiments, in step S4, the velocity information of each grid point at different heights under each typical working condition is integrated to obtain the average flow velocity v at the corresponding height i. ji Specifically:

[0098]

[0099] In the formula, L i L represents the acoustic path length of the fluid layer at height i, which is determined based on the actual acoustic path length under the installation conditions of the ultrasonic transducer in the test environment. i The reconstructed three-dimensional flow field inside the flow measurement section contains n heights, i.e., i takes the values ​​1, 2, ..., n, where n is much greater than n' and n is at least 5 times n'; j represents the j-th typical working condition. ds represents the three-dimensional velocity vector inside the flow measurement section under the j-th typical working condition of the reconstruction; ds represents the linear infinitesimal vector along the integration path.

[0100] The average flow velocity v at n different heights within each flow measurement section under different typical operating conditions was obtained. ji Then, v ji By correlating the flow rates measured by the calibrated flowmeters under corresponding operating conditions, the "average flow velocity v at different heights under typical operating conditions" can be constructed. ji -Traffic Q j "database.

[0101] In some embodiments, in step S5, the sound velocity at which the readings of each ultrasonic flowmeter in the pumping station under test stabilizes is first read under actual operating conditions. Assume there are n' ultrasonic flowmeters in the pumping station under test, evenly distributed at different heights in the flow measurement section. The average sound velocity at the n' heights collected under actual operating conditions is compared with the average flow velocity v at different heights under the j-th typical operating condition in the database using the following formula. ji Correlation analysis was performed to obtain the correlation coefficient s. j :

[0102]

[0103] In the formula, i' is the acoustic path number of the ultrasonic flowmeter in the pumping station to be tested; The average sound velocity of the n' ultrasonic flow meters collected under actual operating conditions is obtained by taking the average value of the n' channel average flow velocities measured by the ultrasonic flow meters in the pump station under test. v is the average sound velocity for the j-th typical working condition in the database; i' The average flow velocity is measured by the i'th ultrasonic flow meter.

[0104] In some embodiments, in step S5, after obtaining N correlation coefficients, the average flow velocity and flow rate corresponding to the n' typical operating conditions with the highest correlation to the measured operating condition are selected as basic data. Finally, the flow rate value Q of the measured operating condition is determined by the Q values ​​corresponding to the selected n' typical operating conditions. k and v ki' The weighted interpolation yields:

[0105]

[0106] In the formula, Q k w represents the flow rate corresponding to the k-th typical operating condition in the selected basic data. ki' λ represents the contribution of the flow rate of the i'th acoustic path to the total flow rate under the k-th typical operating condition in the selected basic data. ki' The average flow velocity measured by the i'th ultrasonic flow meter represents the ratio of the average flow velocity of the i'th ultrasonic path under the kth typical working condition in the selected basic data; A represents the cross-sectional area of ​​the flow path, A = B × H.

[0107] In summary, the present invention provides a flow calculation method for a multi-channel ultrasonic flow meter. Combining the full three-dimensional flow field of the measurement section obtained from the PIV measurement experiment, it further proposes a data integration method for multi-channel ultrasonic flow meters that is most commonly used in large pumping stations with variable rectangular contraction elbow-shaped flow channels. This method can adapt to various ultrasonic transducer installation conditions and improve the measurement accuracy of ultrasonic flow meters under complex operating conditions in large pumping stations.

[0108] A flow calculation device for a multi-channel ultrasonic flow meter, provided in a second aspect embodiment of the present invention, includes:

[0109] The database storage module is used to store the average flow velocity v at different heights under the established typical working conditions. ji -Traffic Q j database;

[0110] The calculation module is used to perform correlation analysis between the average sound velocity measured by all ultrasonic flowmeters in the pumping station under test and the average flow velocity at different heights under various typical conditions in the database under actual test conditions. The average flow velocity and flow rate corresponding to the typical test condition that is most similar to the actual test condition are selected as the basic data, and the flow rate value under the actual test condition is calculated by weighted integral method.

[0111] It should be noted that the foregoing explanation of the embodiment of the flow calculation method of a multi-channel ultrasonic flow meter also applies to the flow calculation device of the multi-channel ultrasonic flow meter in this embodiment, and will not be repeated here.

[0112] To implement the above embodiments, this disclosure also proposes a computer-readable storage medium storing a computer program that is executed by a processor to perform the flow calculation method of the multi-channel ultrasonic flowmeter described above.

[0113] The following is for reference. Figure 6 The diagram illustrates a structural schematic of an electronic device suitable for implementing embodiments of the present disclosure. It should be noted that the electronic devices in the embodiments of the present disclosure may include, but are not limited to, mobile terminals such as mobile phones, laptops, digital broadcast receivers, PDAs (personal digital assistants), PADs (tablet computers), PMPs (portable multimedia players), and in-vehicle terminals (e.g., in-vehicle navigation terminals), as well as fixed terminals such as digital TVs, desktop computers, and servers. Figure 6 The electronic device shown is merely an example and should not be construed as limiting the functionality and scope of the embodiments disclosed herein.

[0114] like Figure 6 As shown, the electronic device may include a processing unit (e.g., a central processing unit, a graphics processing unit, etc.) 101, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 102 or a program loaded from a storage device 108 into a random access memory (RAM) 103. The RAM 103 also stores various programs and data required for the operation of the electronic device. The processing unit 101, ROM 102, and RAM 103 are interconnected via a bus 104. An input / output (I / O) interface 105 is also connected to the bus 104.

[0115] Typically, the following devices can be connected to I / O interface 105: input devices 106 including, for example, touchscreens, touchpads, keyboards, mice, cameras, microphones, etc.; output devices 107 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices 108 including, for example, magnetic tapes, hard disks, etc.; and communication devices 109. Communication device 109 allows electronic devices to communicate wirelessly or wiredly with other devices to exchange data. Although Figure 6 Electronic devices with various devices are shown, but it should be understood that it is not required to implement or have all of the devices shown. More or fewer devices may be implemented or have alternatively.

[0116] In particular, according to embodiments of this disclosure, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, this embodiment includes a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such an embodiment, the computer program can be downloaded and installed from a network via communication device 109, or installed from storage device 108, or installed from ROM 102. When the computer program is executed by processing device 101, it performs the functions defined above in the methods of embodiments of this disclosure.

[0117] It should be noted that the computer-readable medium described in this disclosure can be a computer-readable signal medium or a computer-readable storage medium, or any combination thereof. A computer-readable storage medium can be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this disclosure, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in connection with an instruction execution system, apparatus, or device. In this disclosure, a computer-readable signal medium can include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium can be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to: wires, optical fibers, RF (radio frequency), etc., or any suitable combination thereof.

[0118] The aforementioned computer-readable medium may be included in the aforementioned electronic device; or it may exist independently and not assembled into the electronic device.

[0119] The aforementioned computer-readable medium carries one or more programs, which, when executed by the electronic device, cause the electronic device to perform the aforementioned flow calculation method for the multi-channel ultrasonic flow meter.

[0120] Computer program code for performing the operations of this disclosure can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and Python, as well as conventional procedural programming languages ​​such as the "C-" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0121] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0122] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0123] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the function involved, as will be understood by those skilled in the art to which embodiments of this application pertain.

[0124] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which programs can be printed, because programs can be obtained electronically, for example, by optically scanning the paper or other media, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0125] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0126] Those skilled in the art will understand that implementing all or part of the steps of the methods in the above embodiments can be accomplished by instructing related hardware through a program. The developed program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0127] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0128] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A method for calculating the flow rate of a multi-channel ultrasonic flow meter, characterized in that, include: Step S1: Construct a model test bench for the pump station based on the inlet flow channel of the pump station to be tested. Each pump's outlet pipe is equipped with a calibrated flow meter with a measurement accuracy higher than that of an ultrasonic flow meter. The flow channel section covered by the ultrasonic flow meter installed on a certain unit within the pump station is taken as the measurement section. A PIV testing device is constructed around this section to establish a three-dimensional rectangular coordinate system for the measurement section. Within the measurement section, different Z-coordinates are determined. A test XY section and under different Y coordinates One XZ section to be measured; Step S2: Determine the pump station to be tested. Under typical operating conditions, PIV experiments were conducted on the bidirectional flow field of the inlet water under each typical operating condition, and the readings of the calibrated flowmeter were recorded under each typical operating condition. Particle images of a XY section and b XZ section under various typical working conditions were collected using a PIV testing device. Based on the collected particle images, PIV calculations were performed to obtain the two-dimensional velocity vectors of each measurement section under different typical working conditions. Step S3: Perform two-dimensional interpolation on the two-dimensional velocity vectors of each section to be measured under different typical working conditions to obtain the two-dimensional velocity field of the measuring section; introduce the continuity equation as a physical constraint to perform three-dimensional interpolation on the two-dimensional velocity field to realize the reconstruction of the three-dimensional flow field inside the measuring section under each typical working condition. Step S4: Based on the reconstructed three-dimensional flow field inside the flow measurement section under each typical working condition, integrate the velocity information of each grid point at different heights under each typical working condition to obtain the average flow velocity at the corresponding height i. Establish the average flow velocity at different heights under typical working conditions. -flow Database; among which, The average flow velocity at height i is obtained by integrating the velocity information of each grid point at different heights under various typical working conditions according to the following formula. : In the formula, Represents height The length of the sound path at the location; the three-dimensional flow field inside the reconstructed flow measurement section contains n heights, where i takes the values ​​1, 2, ..., n; The three-dimensional velocity vector inside the flow measurement section represents the j-th typical working condition under reconstruction. Represents the infinitesimal vector of the line element along the integration path; Will By correspondingly mapping the flow rates measured by the calibrated flowmeter under the corresponding operating conditions, the average flow velocity at different heights under the typical operating conditions is obtained. -flow database; Step S5: Under actual operating conditions, perform a correlation analysis between the average sound velocity measured by all ultrasonic flowmeters in the pumping station under test and the average flow velocity at different heights under various typical operating conditions in the database. Select the average flow velocity and flow rate corresponding to the typical operating condition most relevant to the actual operating conditions as the basic data, and calculate the flow rate value under the actual operating conditions using a weighted integral method. The flow rate value under the actual operating conditions is calculated using the following formula: Average sound velocity measured by the ultrasonic flow meter With the database Average flow velocity at different heights under typical working conditions Perform correlation analysis to obtain the correlation coefficient. : In the formula, The acoustic path number of the ultrasonic flowmeter in the pumping station under test; The average sound velocity for the j-th typical working condition in the database; For the first The average flow velocity was measured by an ultrasonic flow meter.

2. The flow calculation method according to claim 1, characterized in that, The pump station model test bench includes an elbow-shaped flow channel, a vertical axial flow pump, an outlet pipe, a connecting pipe, and a circulation pool that are connected in sequence to form a circulation loop. The elbow-shaped flow channel is made of transparent material, and tracer particles are added to the fluid in the circulation loop. The PIV testing equipment includes a transparent water tank, a laser, and a single camera. The elbow-shaped flow channel is set inside the transparent water tank. Each determined test section is marked on the side wall of the transparent water tank to ensure that the plane of the laser generated by the laser coincides with the test section.

3. The flow calculation method according to claim 2, characterized in that, In step S2, when performing a two-dimensional PIV flow field measurement on any XY section under a typical working condition, the following steps are included: Step S211: Adjust the position of the laser installed above the elbow-shaped flow channel so that the sheet light formed by the laser coincides with an XY section to be measured. Step S212: Set up the camera on the side of the elbow-shaped flow channel, make the camera clearly image and ensure that the camera imaging plane is parallel to the XY section to be measured. With the laser off, place the checkerboard calibration plate at the XY section to be measured and take a checkerboard calibration image. Step S213: Take a set of continuous XY cross-sectional particle images for the current XY cross-section to be tested; Step S214: Average the continuous XY cross-sectional particle images to obtain an average particle image containing background information. Subtract the calculated average particle image containing background information from each particle image in the continuous XY cross-sectional particle images to obtain a continuous XY cross-sectional particle image with background light interference removed. Step S215: Perform PIV calculation on the continuous XY cross-section particle image after removing background light interference to obtain the two-dimensional velocity vector of each node in the current XY cross-section under test in pixel units. Combined with the checkerboard calibration image taken in step S212, obtain the first two-dimensional velocity vector (v, u) of each node in the current XY cross-section under test.

4. The flow calculation method according to claim 2, characterized in that, In step S2, when performing PIV two-dimensional flow field measurement on any XZ section to be measured under a typical working condition, the imaging plane of the camera is made horizontal and has an angle with the XZ section to be measured. The particle image of the XZ section to be measured captured by the camera is corrected by perspective using the checkerboard calibration method. Based on the corrected particle image of the XZ section to be measured, the second two-dimensional velocity vector (v, w) of each node in the XZ section to be measured is obtained.

5. The flow calculation method according to claim 1, characterized in that, In step S3, when the continuity equation is introduced as a physical constraint to perform three-dimensional interpolation on the two-dimensional velocity field, the target value of the change of the average velocity along the flow path on each YZ section of the elbow-shaped channel within the flow measurement section is defined. By minimizing the deviation between the adjusted velocity field and the initial three-dimensional interpolation result, the final reconstruction result is ensured to meet the physical constraint.

6. The flow calculation method according to claim 1, characterized in that, In step S5, selecting the average flow velocity and flow rate corresponding to the typical operating condition most relevant to the measured operating condition as basic data, and calculating the flow rate value of the measured operating condition using a weighted integral method, includes: After obtaining N correlation coefficients, the average flow velocity and flow rate corresponding to the n' typical operating conditions with the highest correlation to the measured operating conditions are selected as the basic data. Finally, the flow rate value Q of the measured operating condition is determined by the average flow velocity and flow rate corresponding to the n' typical operating conditions. and The weighted interpolation yields: In the formula, This represents the flow rate corresponding to the k-th typical operating condition in the selected basic data. This represents the k-th typical working condition in the selected basic data, and the... The contribution of each path's flow to the total flow. Representing the The average flow velocity measured by the ultrasonic flow meter is compared with the k-th typical operating condition in the selected basic data. The proportional relationship between the average flow velocity of each sound path; A is the cross-sectional area of ​​the flow path.

7. A flow calculation device for a multi-channel ultrasonic flow meter, characterized in that, include: The database storage module is used to store the average flow velocity at different heights under the typical operating conditions established in the flow calculation method according to any one of claims 1 to 6. -flow database; The calculation module is used to perform correlation analysis between the average sound velocity measured by all ultrasonic flowmeters in the pumping station under test and the average flow velocity at different heights under various typical conditions in the database under actual test conditions. The average flow velocity and flow rate corresponding to the typical test condition that is most similar to the actual test condition are selected as the basic data, and the flow rate value under the actual test condition is calculated by weighted integral method.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to perform the flow calculation method according to any one of claims 1 to 6.

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