CN-120831150-B - Flow calculation method, device and storage medium of multi-acoustic path ultrasonic flowmeter

CN120831150BCN 120831150 BCN120831150 BCN 120831150BCN-120831150-B

Abstract

The invention discloses a flow calculation method of a multi-acoustic path ultrasonic flowmeter, which aims at solving the problems that the flow measurement precision of a traditional multi-acoustic path time difference ultrasonic flowmeter under chaotic flow caused by complex and variable operation conditions of a large pump station cannot be met by a fixed weight function flow integration method of the traditional multi-acoustic path time difference ultrasonic flowmeter, the invention obtains a full three-dimensional flow field in a flow measurement section and average flow velocity v ji corresponding to flow Q j and a plurality of different heights by completing a water inlet flow state bidirectional flow field PIV experiment under each typical working condition of the large pump station, and establishing an average flow velocity v ji -flow Q j database at different heights under the typical working condition, and weighting and integrating the flow under the typical working condition based on the correlation analysis of the measured average flow velocity and the average flow velocity at the relative height of the typical working condition to obtain the flow value of the measured working condition, thereby improving the measurement accuracy of the flow integration algorithm of the ultrasonic flowmeter under the extreme working conditions of the large pump station by the multi-channel time difference method.

Inventors

ZHONG QIANG
CHEN MENGTING
WANG FUJUN
YAO ZHIFENG
LENG JIQIANG
LU PING

Assignees

中国农业大学
青岛清万水技术有限公司

Dates

Publication Date: 20260508
Application Date: 20250717

Claims (8)

1. A flow calculation method of a multi-acoustic path ultrasonic flowmeter, comprising: Step S1, building a pump station model experiment table according to a water inlet flow channel of a pump station to be tested, wherein a calibration flowmeter with measurement accuracy higher than that of an ultrasonic flowmeter is arranged on a water outlet pipe corresponding to each pump XY sections to be measured and under different Y coordinates XZ sections to be measured; Step S2, determining the pump station to be tested Developing a two-way flow field PIV experiment of water inflow state under each typical working condition, recording the calibration flowmeter indication under each typical working condition Acquiring particle images of a to-be-measured XY section and b to-be-measured XZ section under each typical working condition by using PIV test equipment; S3, carrying out two-dimensional interpolation on two-dimensional flow velocity vectors of each section to be measured under different typical working conditions to obtain a two-dimensional flow velocity field of a flow measurement section; S4, integrating the speed information of each grid point at different heights under each typical working condition according to the reconstructed three-dimensional flow field in the flow measuring section under each typical working condition to obtain the average flow velocity at the corresponding height i Establishing average flow rates at different heights under typical conditions -Flow rate A database, wherein, the database comprises a plurality of data sets, The average flow velocity 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 method : In the formula, Representative height The acoustic path length at the position, the three-dimensional flow field inside the reconstructed flow measurement section contains n heights, i is 1,2, & gt, n; Representing the three-dimensional flow velocity vector in the flow measuring section under the reconstructed j-th typical working condition; Representing a line infinitesimal vector along the integration path; Will be One-to-one correspondence with the flow measured by the calibration flow meter under the corresponding working condition to obtain the average flow velocity at different heights under the typical working condition -Flow rate A database; S5, under the actual measurement working condition, carrying out correlation analysis on the average value of sound velocity measured by all ultrasonic flow meters in the pump station to be measured and the average flow rates at different heights under each typical working condition in a database, selecting the average flow rate and the flow rate corresponding to the typical working condition most relevant to the actual measurement working condition as basic data, and calculating the flow value of the actual measurement working condition by adopting a weighted integration method, wherein the average flow rate and the flow rate in the typical working condition are calculated according to the following steps Average value of sound velocity measured by ultrasonic road flowmeter With database 1 Average flow rate at different heights under typical conditions Performing correlation analysis to obtain a correlation coefficient : In the formula, Numbering the acoustic path of the ultrasonic flowmeter in the pump station to be tested; The average value of sound velocity of the j-th typical working condition in the database; Is the first The average flow rate measured by the ultrasonic flow meter.
2. The flow calculation method according to claim 1, wherein the pump station model experiment table comprises an elbow-shaped flow passage, a vertical axial flow pump, a water outlet pipe, a connecting pipe and a circulating pool which are sequentially connected to form a circulating loop, the elbow-shaped flow passage is made of transparent materials, and trace particles are added into fluid of the circulating loop; The PIV testing equipment comprises a transparent water tank, a laser and a single camera, wherein the elbow-shaped flow channel is arranged in the transparent water tank, and the side wall of the transparent water tank is marked with each determined section to be tested to ensure that the plane of laser generated by the laser coincides with the section to be tested.
3. The flow computing method according to claim 2, wherein in step S2, when performing PIV two-dimensional flow field measurement on any XY section to be measured under a certain typical working condition, the method includes: Step S211, adjusting the position of a laser arranged above the elbow-shaped flow channel to enable the sheet light formed by the laser to coincide with one XY section to be tested currently; Step S212, arranging the camera frame on the side surface of the elbow-shaped runner, enabling the camera to image clearly and ensuring that an imaging plane of the camera is parallel to the current XY section to be measured, and under the condition that a laser is closed, placing a checkerboard calibration plate at the current XY section to be measured and shooting a checkerboard calibration image; Step S213, shooting a group of continuous XY section particle images on the current XY section to be detected; Step S214, averaging the continuous XY section particle images to obtain average particle images containing background information, and subtracting the calculated average particle images containing the background information from each particle image in the continuous XY section particle images to obtain continuous XY section particle images with background light interference removed; And S215, performing PIV calculation on the continuous XY section particle images with the background light interference removed to obtain two-dimensional flow velocity vectors of all nodes in the current XY section to be detected in pixel units, and combining the checkerboard calibration images shot in the S212 to obtain first two-dimensional flow velocity vectors (v, u) of all nodes in the current XY section to be detected.
4. The flow computing method according to claim 2, wherein in step S2, when performing PIV two-dimensional flow field measurement on any XZ cross section to be measured under a certain typical working condition, an imaging plane of the camera is made to be horizontal, an included angle exists between the imaging plane and the XZ cross section to be measured, perspective correction is performed on an XZ cross section particle image to be measured shot by the camera by using a checkerboard calibration method, and a second two-dimensional flow velocity vector (v, w) of each node in the XZ cross section to be measured is obtained based on the corrected XZ cross section particle image to be measured.
5. The flow computing method according to claim 1, wherein in step S3, when introducing a continuity equation as a physical constraint to perform three-dimensional interpolation on the two-dimensional flow velocity field, a target value of a change of an average flow velocity along a flow path on each YZ section of the elbow-shaped flow channel in the flow measuring section is defined, and a final reconstruction result is ensured to satisfy the physical constraint by minimizing a deviation between the adjusted velocity field and an initial three-dimensional interpolation result.
6. The flow rate calculating method according to claim 1, wherein in step S5, the selecting, as the basic data, the average flow rate and the flow rate corresponding to the typical condition most relevant to the measured condition, and calculating the flow rate value of the measured condition by using a weighted integration method includes: after N correlation coefficients are obtained, selecting average flow velocity and flow thereof corresponding to N 'typical working conditions with highest correlation with the actual working conditions as basic data, and finally obtaining the flow value Q of the actual working conditions corresponding to the selected N' typical working conditions And And obtaining by weighted interpolation: in the formula, Representing the flow corresponding to the kth typical condition in the selected base data, Representing the kth typical condition, the kth in the selected basic data The contribution of the flow of the individual acoustic paths to the total flow, Represents the first The average flow velocity measured by the ultrasonic road flow meter and the kth typical working condition in the selected basic data Proportional relation of average flow velocity of each acoustic path, and area of flow cross section A.
7. A flow rate calculation device of a multi-acoustic path ultrasonic flowmeter, comprising: A database storage module for storing average flow velocity at different heights under the typical working conditions established in the flow calculation method according to any one of claims 1 to 6 -Flow rate A database; And the calculation module is used for carrying out correlation analysis on the average value of sound speeds measured by all ultrasonic flow meters in the pump station to be measured and the average flow rates at different heights under each typical working condition in the database under the actual measurement working condition, selecting the average flow rate and the flow rate corresponding to the typical working condition which is most similar to the actual measurement working condition as basic data, and calculating the flow value of the actual measurement working condition by adopting a weighted integration method.
8. A computer-readable storage medium storing computer instructions for causing the computer to execute the flow rate calculation method according to any one of claims 1 to 6.

Description

Flow calculation method, device and storage medium of multi-acoustic path ultrasonic flowmeter Technical Field The invention relates to the technical field of ultrasonic flowmeter flow measurement, in particular to a flow calculation method, a flow calculation device and a storage medium of a multi-channel acoustic flowmeter. Technical Field The real-time flow of each unit of the large pump station is an important basis for water scheduling decision of the large pump station. In the current flow measurement methods of large pump stations, the multi-acoustic ultrasonic flowmeter is increasingly applied to the real-time flow measurement of the large pump stations due to the advantages of non-contact, large-scale measurement and the like, and each large pump station currently adopts the ultrasonic flowmeter of the multi-acoustic time difference method arranged on the rectangular constricted section of the inlet to carry out the real-time flow measurement. The time difference flow meter is actually to vector-superimpose the ultrasonic wave propagation speed and the fluid flow velocity, and reflect the flow velocity by measuring the time difference between the forward flow and the backward flow of the ultrasonic wave. Because the mono ultrasonic flowmeter is easily affected by flow velocity distribution, the actual condition of the flow field in the pipeline cannot be fully reflected. Therefore, for the actual situations of large pump station with more working conditions and complicated flow states, a plurality of pairs of ultrasonic transducers are required to be arranged in a flow channel, the flow section is uniformly divided into a plurality of flow layers, the average flow velocity of each flow layer is determined by the average flow velocity of an acoustic route in the flow layer, and then the flow value is calculated by using a flow integration method based on Gaussian-Legend (Gauss-Legender) integration. The existing ultrasonic flowmeter flow integration method has the problem that the preset average speed distribution of the sound channel is fixed and does not change along with the flowing state. In actual extreme working conditions, the flow state distribution of the flow channels is very chaotic, and the existing integration method cannot accurately identify bad flow states such as backflow, vortex and the like, so that the measurement accuracy of the ultrasonic flowmeter is greatly reduced. In the actual operation of a large pump station, the maximum error of the readings of the ultrasonic flowmeter by the cross double-channel surface multi-channel time difference method under the extreme working condition can reach 30%, the real-time flow of the pump station under the extreme working condition can not be accurately determined, and the flow error directly affects the rationality of the scheduling decisions of all levels. On the other hand, because the ultrasonic transducer in the ultrasonic flowmeter belongs to the pump station embedded device, once the pump station is built, the measurement accuracy of the ultrasonic flowmeter under the extreme working condition cannot be improved by adding the number of sound paths. Taking a single-channel time difference flow meter as an example, the measurement principle is shown in fig. 1, S is the linear distance of an ultrasonic flowmeter transducer, alpha is the included angle between the axis of a flow channel and the acoustic path of the transducer, the propagation speed of ultrasonic waves in static fluid is c, the flow velocity of the fluid in a pipeline to be measured is v, the forward propagation time of the ultrasonic waves is T 1, the counter-current propagation time is T 2, and the calculation formula is as follows: for a liquid ultrasonic flowmeter, the propagation speed of ultrasonic waves in still water is about 1500m/s, and according to the measurement range of the ultrasonic flowmeter, the flow speed of liquid to be measured is generally considered to be far smaller than the propagation speed of the ultrasonic waves, and the calculation formula of the axial average flow velocity of the fluid of the flow section to be measured is as follows: And calculating the formula Q=AV according to the flow, wherein A is the area of the flow cross section to be measured. The mono ultrasonic flowmeter is easily affected by flow velocity distribution, and cannot fully reflect the actual condition of the flow field in the pipeline. For the actual conditions of large pump station with multiple working conditions and complex flow state, a plurality of pairs of cross sound channels are required to be arranged in the flow channel, the flow cross section is uniformly divided into a plurality of flow layers, and the average axial flow velocity of each flow layer is determined by the average flow velocity of the cross sound paths in the flow layers. The traditional flow integration method of the rectangular pipeline is Gaussian-Legend (Gaussian-Legender) integration,