Ultrasonic flowmeter calibration device and calibration method thereof

Abstract

An ultrasonic flowmeter calibration device and calibration method thereof, comprising a pressure-stabilizing water tank for providing a stable water outlet pressure, a water pipe connected to the pressure-stabilizing water tank at one end, and a plurality of drainage pipes for supporting the ultrasonic flowmeter to be calibrated, wherein the cross-sectional shapes of the plurality of drainage pipes are different, the water pipe comprises a main water pipe connected to the pressure-stabilizing water tank at one end, and a plurality of branch pipes respectively connected to each drainage pipe, each branch pipe being connected to the main water pipe, a standard flowmeter for detecting the water flow in the main water pipe and a flow regulating valve for regulating the water flow in the main water pipe being installed on the main water pipe, and a control valve for controlling the on-off of the branch pipe being installed on each branch pipe. The ultrasonic flowmeter calibration device and calibration method provided by the present application adopt drainage pipes with different cross-sections, thereby reducing the difference in the calibration of ultrasonic flowmeters to be calibrated on different drainage pipes, and reducing the error in flow detection after calibration of different ultrasonic flowmeters to be calibrated.

Description

Technical Field

[0001] The present application belongs to the technical field of flowmeters, and more specifically, to an ultrasonic flowmeter calibration device and a calibration method thereof. Background Art

[0002] In urban construction, the construction of drainage pipe networks is particularly important. If the drainage pipe network is not designed properly, it will cause low urban drainage efficiency and easily lead to urban waterlogging. When designing drainage pipes, it is necessary to consider the drainage flow rate. Usually, a certain amount of drainage margin is reserved, which makes the water in the drainage pipes usually not full.

[0003] In order to accurately measure the drainage flow in the drainage pipe, it is necessary to install the corresponding ultrasonic flowmeter. When the ultrasonic flowmeter is produced, it is necessary to implant the corresponding reference function in the ultrasonic flowmeter to convert the signal value of the ultrasonic flowmeter into the corresponding flow value; when the ultrasonic flowmeter is installed, the reference function in the ultrasonic flowmeter is calibrated according to the flow value of the actual installation pipe. However, due to certain differences in the cross-sectional shape of the actual application pipes, when the reference function in the existing calibration method is applied to different pipes, the reference function and the actual flow value may be inconsistent with the law of the signal value of the ultrasonic flowmeter to be calibrated, which leads to large differences in the calibration of the ultrasonic flowmeters to be calibrated on different pipes, and the calibration error is large. Summary of the invention

[0004] The purpose of the present application is to provide an ultrasonic flow meter calibration device, including but not limited to solving the technical problems that the ultrasonic flow meter calibration method in the prior art has large calibration differences and large calibration errors when calibrating ultrasonic flow meters to be calibrated on different pipelines.

[0005] In order to solve the above technical problems, an embodiment of the present application provides an ultrasonic flowmeter calibration device, which is characterized in that it includes a pressure-stabilizing water tank for providing a stable water outlet pressure, a water pipe connected to the pressure-stabilizing water tank at one end, and a plurality of drainage pipes for supporting the ultrasonic flowmeter to be calibrated, wherein the cross-sectional shapes of the plurality of drainage pipes are different, the water pipe includes a water main pipe connected to the pressure-stabilizing water tank at one end, and a plurality of branch pipes respectively connected to the drainage pipes, each of the branch pipes is connected to the water main pipe, a standard flowmeter for detecting the water flow in the water main pipe and a flow regulating valve for adjusting the water flow in the water main pipe are installed on the water main pipe, and a control valve for controlling the on and off of the branch pipe is installed on each of the branch pipes.

[0006] Furthermore, a liquid level sensor is provided at the bottom of the pressure-stabilizing water tank.

[0007] Furthermore, the pressure-stabilizing water tank is connected to a water supply pipe, and a liquid level regulating valve is installed on the water supply pipe.

[0008] Furthermore, the ultrasonic flowmeter calibration device also includes a water return component for conveying the drainage from each of the drainage pipes to the pressure-stabilizing water tank.

[0009] Furthermore, the water return assembly includes a collecting tank for collecting drainage from each drainage pipe, a water return pipe connecting the collecting tank and the pressure-stabilizing water tank, and a reflux pump installed on the water return pipe.

[0010] Furthermore, the reflux pump is a variable frequency pump.

[0011] The present application also provides an ultrasonic flowmeter calibration method, which uses the ultrasonic flowmeter calibration device described in any of the above embodiments to calibrate the ultrasonic flowmeter to be calibrated, and the ultrasonic flowmeter calibration method includes the following steps:

[0012] S1. Installing the ultrasonic flowmeter to be calibrated on each of the drainage pipes;

[0013] S2, control the water flow in the water main pipe to flow out through each of the drainage pipes in sequence, and when the water flows through each of the drainage pipes, control the water flow rate of the water main pipe, so that multiple groups of flow values ​​(Q) of each of the drainage pipes can be obtained. raw_value , Q stan._value ), where Q raw_value is the flow value of the ultrasonic flowmeter to be calibrated, Q stan._value is the standard flow value corresponding to the standard flow meter on the water main;

[0014] S3, according to the multiple groups Q in step S2 raw_value and Q stan._value The value of is used for curve fitting to obtain the reference function f of the ultrasonic flowmeter to be calibrated base (Q raw_value , Q stan._value );

[0015] S4, the benchmark function f base (Q raw_value , Q stan._value ) implant each ultrasonic flow meter to be calibrated.

[0016] Furthermore, after step S4, the method further includes:

[0017] S5, selecting the drainage pipe with a cross section similar to that of the application pipe of the ultrasonic flowmeter to be calibrated, and installing the ultrasonic flowmeter to be calibrated on the drainage pipe;

[0018] S6, controlling the water flow in the water main pipe to be discharged from the drain pipe, and controlling the water flow in the water main pipe to obtain multiple flow values ​​Q of the ultrasonic flowmeter to be calibrated raw_value_i , and the standard flow value Q corresponding to the standard flow meter on the water main pipe stan._value_i ;

[0019] S7, according to each group Q in step S6 raw_value_i and Q stan._value_i The value of the benchmark function f base (Q raw_value , Q stan._value ) to obtain the calibration function f of the ultrasonic flowmeter to be calibrated cal .(Q raw_value , Q stan._value );

[0020] S8, the reference function f in the ultrasonic flowmeter to be calibrated base (Q raw_value , Q stan._value ) is corrected to the calibration function f cal .(Q raw_value , Q stan._value ).

[0021] Furthermore, step S2 also includes: controlling the water flow in the water main pipe, adjusting the water pressure in the pressure-stabilizing water tank, and stabilizing the water pressure in the pressure-stabilizing water tank; after the water flow pressure and flow in the drainage pipe are stable, obtaining the flow value Q of the ultrasonic flowmeter to be calibrated in the drainage pipe. raw_value_i , and the standard flow value Q corresponding to the standard flow meter on the water main pipe stan._value_i .

[0022] Furthermore, step S2 also includes: obtaining the flow value Q of the ultrasonic flowmeter to be calibrated raw_value is the cumulative flow rate q of the ultrasonic flowmeter to be calibrated within the time Δt raw .Calculate the average water flow value; obtain the standard flow value Q stan._value is the cumulative flow rate q measured by the standard flow meter within time Δt stan Calculate the average water flow value.

[0023] The ultrasonic flowmeter calibration device and calibration method provided in the present application adopt a pressure-stabilizing water tank to provide a stable water delivery pressure, so that a stable water flow can be obtained in each drainage pipe; by adopting drainage pipes with different cross-sections, non-full flow data of drainage pipes with different cross-sections can be obtained, and then a reference function suitable for drainage pipes with a variety of different cross-sections can be calculated, thereby realizing the setting of a reference function for the ultrasonic flowmeter to be calibrated, so that the reference function in the ultrasonic flowmeter to be calibrated can be applicable to drainage pipes with different cross-sections, reducing the difference in the calibration of the ultrasonic flowmeters to be calibrated on different drainage pipes, and reducing the error of flow detection after calibration of different ultrasonic flowmeters to be calibrated. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0025] Figure 1 A schematic diagram of the structure of an ultrasonic flowmeter calibration device provided in Example 1 of the present application;

[0026] Figure 2 A schematic diagram of the structure of an ultrasonic flowmeter calibration device provided in Example 2 of the present application;

[0027] Figure 3 A schematic diagram of the structure of an ultrasonic flowmeter calibration device provided in Example 3 of the present application;

[0028] Figure 4 This is a schematic diagram of water flow in Example 1 of the present application.

[0029] Among them, the reference numerals in the figure are:

[0030] 11—pressure-stabilizing water tank, 21—water delivery pipe, 21a—water delivery main pipe, 21b—branch pipe, 23—standard flow meter, 24—flow regulating valve, 25—control valve, 31—drain pipe, 32—ultrasonic flow meter to be calibrated, 41—water supply pipe, 42—liquid level regulating valve, 51—collecting tank, 52—return pipe, 53—reflux pump. DETAILED DESCRIPTION

[0031] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0032] In the description of the present application, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0033] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0034] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0035] Please also read Figures 1 to 4, the ultrasonic flowmeter calibration device provided by the present application is now described. The ultrasonic flowmeter calibration device includes a pressure-stabilizing water tank 11, a water pipe 21 and a plurality of drainage pipes 31. One end of the water pipe 21 is connected to the pressure-stabilizing water tank 11, and the other end of the water pipe 21 is connected to each drainage pipe 31; the pressure-stabilizing water tank 11 provides a water flow with a stable pressure to the water pipe 21, and the water flows to any drainage pipe 31 through the water pipe 21. The water pipe 21 includes a main water pipe 21a and a plurality of branch pipes 21b, one end of the main water pipe 21a is connected to the pressure-stabilizing water tank 11, and each branch pipe 21b is respectively connected to each drainage pipe 31, and each branch pipe 21b is connected to the main water pipe 21a. A standard flowmeter 23 and a flow regulating valve 24 are installed on the main water pipe 21a. The standard flowmeter 23 is used to detect the flow in the main water pipe 21a, and the flow regulating valve 24 is used to adjust the water flow in the main water pipe 21a. A control valve 25 is installed on each branch pipe 21b, and the control valve 25 is used to control the on and off of the branch pipe 21b. Each drain pipe 31 can support the installation of an ultrasonic flowmeter 32 to be calibrated. Among them, each ultrasonic flowmeter 32 to be calibrated has the same model. The use of a pressure-stabilizing water tank 11 can provide a stable water delivery pressure for the water delivery main pipe 21a, so that a stable water flow can be obtained in each drain pipe 31; using drain pipes 31 with different cross sections, non-full flow data of drain pipes 31 with different cross sections under a stable water flow can be obtained. After curve fitting of multiple sets of data of drain pipes 31 with different cross sections, a reference function between the standard flow and the display value of the ultrasonic flowmeter 32 to be calibrated can be obtained. Since the reference function uses data obtained from drain pipes 31 with different cross sections, its reference function has a wider adaptability, that is, after the ultrasonic flowmeter to be calibrated of the reference function is used for drain pipes with different cross-sectional shapes, although there is a certain difference with the actual flow of the drain pipe, its display value can be kept consistent with the actual flow law of drain pipes with various cross sections. Using drainage pipes 31 with different cross-sections to calibrate and obtain a reference function can reduce the difference between the reference function and drainage pipes 31 with different cross-sections. When calibrating the coefficients of the reference function, the error caused by the difference in the reference function can be reduced, thereby reducing the calibration error and improving the accuracy of the ultrasonic flow meter 32 to be calibrated after detection.

[0036] For example, when curve fitting is performed on three sets of data obtained from a drainage pipe 31, different functional relationships can be obtained by using exponential relationships, linear relationships, logarithmic relationships or polynomial relationships, among which a trinomial function that satisfies the three sets of data is obtained; when the three sets of data are just in a linear relationship, there are at least two functions that can completely fit the three sets of data. When fitting is performed on six sets of data obtained from two different drainage pipes 31, it is assumed that the standard flow values ​​in the three sets of data of the two drainage pipes 31 are respectively equal, but the corresponding display values ​​in the two sets of data may be greatly different. At this time, the function obtained by curve fitting of the three sets of data of any drainage pipe 31 is greatly different from the function obtained by curve fitting of the other drainage pipe 31, so that when the ultrasonic flowmeter 32 to be calibrated adopts the reference function obtained by curve fitting of the data of the first drainage pipe 31 and is installed on the second drainage pipe 31, its error is extremely large, and it may even lead to the inability to calibrate the ultrasonic flowmeter through the data obtained from the second drainage pipe to reduce this error. The main factor causing this difference is the different cross-sectional shapes of the drainage pipes. Although the correlation coefficient of the function obtained by curve fitting using six sets of data is smaller than the correlation coefficient of the function obtained by curve fitting using three sets of data on any drain pipe 31, the correlation coefficient of the function relative to the six sets of data is greater than the correlation coefficient of the function fitted by three sets of data on any drain pipe 31 relative to the six sets of data, that is, it can make the data of various drain pipes 31 closer to the obtained function. The function can be used as the reference function of the ultrasonic flowmeter 32 to be calibrated. When the ultrasonic flowmeter 32 to be calibrated is installed on a specific drain pipe 31, the ultrasonic flowmeter 32 can be further calibrated by the data obtained from the drain pipe 31. Since the obtained data is closer to the curve of the reference function, it is convenient to calibrate the reference function to a calibration function suitable for the drain pipe 31. This avoids the problem of differences in the reference equations obtained by using a single-shaped cross-section drain pipe in the existing calibration method.

[0037] Furthermore, the drain pipe 31 includes a trapezoidal drain pipe 31 with a trapezoidal cross section. Trapezoidal is a commonly used cross-sectional shape for pipes and canals. The drain pipe 31 with a trapezoidal cross section can correspond to common pipes and canals with a trapezoidal cross section, thereby reducing the calibration error of the ultrasonic flowmeter installed on the pipes and canals with a trapezoidal cross section.

[0038] Furthermore, the drain pipe 31 includes a circular drain pipe 31 with a circular cross-section. A circular pipe is a commonly used cross-sectional shape for pipes and canals. The drain pipe 31 with a circular cross-section can correspond to common circular cross-section pipes and canals, thereby reducing the calibration error of the ultrasonic flowmeter installed on the circular cross-section pipes and canals.

[0039] Furthermore, the drain pipe 31 includes a trapezoidal drain pipe 31 with a trapezoidal cross section and a circular drain pipe 31 with a circular cross section. This can not only meet the calibration of pipes with common cross-sectional shapes, but also be applicable to the calibration cross section of ultrasonic flowmeters on pipes with similar cross-sectional shapes to the two pipes, such as pipes with a horizontal bottom and parabolic or arc-shaped surfaces on both sides.

[0040] Furthermore, a liquid level sensor is provided at the bottom of the pressure-stabilizing water tank 11, which facilitates the control of the liquid level in the pressure-stabilizing water tank 11 to avoid the impact of liquid level fluctuations in the pressure-stabilizing water tank 11 on the water flow in the water main 21a, causing fluctuations in water flow pressure and flow.

[0041] Furthermore, the pressure-stabilizing water tank 11 is connected with a water supply pipe 41, which can add water to the pressure-stabilizing water tank 11 to control the stability of the pressure at the connection position between the pressure-stabilizing water tank 11 and the water supply pipe 21. A liquid level regulating valve 42 is installed on the water supply pipe 41 to adjust the amount of water injected into the pressure-stabilizing water tank 11 by the water supply pipe 41. In this way, the water pressure during the calibration process can be controlled so that the ultrasonic flowmeter to be tested and the standard flowmeter 23 can be at the same pressure, avoiding pressure fluctuations that interfere with the original flow value of the ultrasonic flowmeter 32 to be calibrated and the standard flow value detected by the standard flowmeter 23, thereby affecting the accuracy of the calibration result. On the other hand, the water supply pipe 41 can add water to the pressure-stabilizing water tank 11 when there is no water or water shortage in the pressure-stabilizing water tank 11.

[0042] Furthermore, the ultrasonic flowmeter calibration device also includes a water return component, which is used to transport the drainage of each drainage pipe 31 to the pressure-stabilizing water tank 11. In this way, the water in the ultrasonic flowmeter calibration device can be recycled. Moreover, when the water return component cooperates with the water supply pipe 41, the size of the water supply pipe can be reduced to accurately control the water supply amount of the pressure-stabilizing water tank 11 and achieve fine adjustment of the liquid level in the pressure-stabilizing water tank 11; the water flow in the entire ultrasonic flowmeter calibration device is relatively stable through the water return component.

[0043] Please also refer to Figure 2 , Figure 3 and Figure 4 As a specific implementation of the ultrasonic flowmeter calibration device provided in the embodiment of the present application, the return water assembly includes a collection tank 51, a return water pipe 52 and a reflux pump 53. The collection tank 51 is used to collect the drainage of each drainage pipe 31, the return water pipe 52 connects the collection tank 51 with the pressure-stabilizing water tank 11, and the reflux pump 53 is installed on the return water pipe 52 to transport the water in the collection tank 51 to the pressure-stabilizing water tank 11. When collecting the drainage in the drainage pipe 31, the collection tank 51 can also eliminate the pulses in the water flow, so as to avoid the pulses in the water flow from impacting the water flow in the return water pipe 52 and affecting the stability in the pressure-stabilizing water tank 11.

[0044] Specifically, the pressure-stabilizing water tank 11 can be a sealed tank, with a compressed air air pipe and an exhaust pipe connected to the top of the sealed tank, and compressed air is introduced into the top of the pressure-stabilizing water tank 11; a pressure sensor is arranged at the top of the pressure-stabilizing water tank 11, and compressed air is introduced into the top of the pressure-stabilizing water tank 11 according to the pressure value of the pressure-stabilizing water tank 11, or compressed air is released to keep the outlet water pressure of the pressure-stabilizing water tank 11 stable; the liquid level in the pressure-stabilizing water tank 11 is maintained stable by the reflux pump 53 and the liquid level regulating valve 42 of the water supply pipe 41. On the one hand, the use of compressed air can eliminate the impact on the internal water pressure of the pressure-stabilizing water tank 11 caused by the water flow entering the pressure-stabilizing water tank 11, and reduce the fluctuation of the internal water pressure and water flow; on the other hand, the use of compressed air can adjust the pressure of the pressure-stabilizing water tank 11 as needed, which is conducive to reducing the volume of the pressure-stabilizing water tank 11.

[0045] Of course, the pressure-stabilizing water tank 11 may also be an overflow tank with an opening at the top, so that the liquid level and pressure inside the pressure-stabilizing water tank 11 can be kept stable through overflow.

[0046] Specifically, the reflux pump 53 is a variable frequency pump. The use of the variable frequency pump can adjust the flow rate of the reflux water so that the water flow maintains a stable circulation between the reflux tank and the pressure-stabilizing water tank 11.

[0047] Preferably, each drainage pipe 31 is made of concrete, which can ensure that the material of the drainage pipe 31 is basically consistent with that of the actual installed pipe, thereby avoiding errors caused by the pipe material after the ultrasonic flowmeter 32 to be calibrated is installed.

[0048] The present application also provides an ultrasonic flowmeter calibration method, which uses the ultrasonic flowmeter calibration device described in any of the above embodiments to calibrate the ultrasonic flowmeter to be calibrated. The calibration method includes the following steps:

[0049] S1. Install the ultrasonic flowmeter to be calibrated on each drainage pipe;

[0050] S2, control the water flow in the water main pipe to flow out through each of the drainage pipes in sequence, and when the water flows through each of the drainage pipes, control the water flow rate of the water main pipe, so that multiple groups of flow values ​​(Q) of each of the drainage pipes can be obtained. raw_value , Q stan._value ), where Q raw_value is the flow value (detection signal value) of the ultrasonic flowmeter to be calibrated, Q stan._value is the standard flow value corresponding to the standard flow meter on the water main;

[0051] S3, according to the multiple groups Q in step S2 raw_value and Q stan._value The value of is used for curve fitting to obtain the reference function f of the ultrasonic flowmeter to be calibrated base (Q raw_value , Q stan._value );

[0052] S4, the benchmark function f base (Q raw_value , Q stan._value ) implant each ultrasonic flow meter to be calibrated.

[0053] By using a plurality of drainage pipes 31 with different cross sections, it is possible to obtain a plurality of groups of flow values ​​Q of the ultrasonic flow meter 32 to be calibrated for the drainage pipes 31 with different cross sections. raw_value And the corresponding standard flow value Q stan._value When performing curve fitting, the obtained reference function can adapt to the flow measurement of drainage pipes 31 with more different cross-section shapes. The reference function here can be embedded in the ultrasonic flowmeter when the ultrasonic flowmeter is produced, so that when the ultrasonic flowmeter is installed in a specific application pipeline, the reference function f in the ultrasonic flowmeter can be further calibrated according to the flow data on the pipeline and the detection value of the ultrasonic flowmeter. base (Q raw_value , Q stan._value ) coefficient, thereby reducing the error of the ultrasonic flowmeter. Since the reference equation used in the ultrasonic flowmeter calibration method is derived from the curve fitting of different drain pipes, this avoids the ultrasonic flowmeter being affected by the difference in depth and flow rate of a single drain pipe, which makes the reference equation too error-prone when applied to drain pipes of other cross-section shapes, and even if the actual flow rate on the pipe is used for calibration, the error caused by the reference function cannot be corrected.

[0054] Optionally, in step S3, Get the reference function f of the ultrasonic flowmeter to be calibrated base (Q raw_value , Q stan._value ) coefficients k0, k1 and k2. Of course, in other embodiments of the present application, other methods may be used for fitting, such as using formula Q stan._value_i =k0+k1ln(Q raw_value_i )+k2ln 2 (Q raw_value_i ) to solve for the coefficients.

[0055] Furthermore, after step S4, the method further includes:

[0056] S5, selecting the drainage pipe with a cross section similar to that of the application pipe of the ultrasonic flowmeter to be calibrated, and installing the ultrasonic flowmeter to be calibrated on the drainage pipe;

[0057] S6, controlling the water flow in the water main pipe to be discharged from the drain pipe, and controlling the water flow in the water main pipe to obtain multiple flow values ​​Q of the ultrasonic flowmeter to be calibratedraw_value_i , and the standard flow value Q corresponding to the standard flow meter on the water main pipe stan._value_i ;

[0058] S7, according to each group Q in step S6 raw_value_i and Q stan._value_i The value of the benchmark function f base (Q raw_value , Q stan._value ) to obtain the calibration function f of the ultrasonic flowmeter to be calibrated cal .(Q raw_value , Q stan._value );

[0059] S8, the reference function f in the ultrasonic flowmeter to be calibrated base (Q raw_value , Q stan._value ) is corrected to the calibration function f cal .(Q raw_value , Q stan._value ).

[0060] In the above steps S5-S8, a drainage pipe with a similar cross section to the application pipe of the ultrasonic flowmeter to be calibrated is selected, and the ultrasonic flowmeter to be calibrated is installed on the drainage pipe to simulate the actual installation pipe of the ultrasonic flowmeter to be calibrated. raw_value_i , Q stan._value_i ), to adjust the reference function f implanted in the ultrasonic flow meter in step S4 base (Q raw_value , Q stan._value ) is further calibrated to reduce the error between the displayed value and the true value of the ultrasonic flowmeter to be calibrated. raw_value_i Indicates the flow value of the ultrasonic flowmeter to be calibrated on the selected drainage pipe, Q stan._value_i Indicates the standard flow value corresponding to the standard flow meter. Here, the correspondence is the standard flow value of the standard flow meter at the same time (or in the same period of time) and the flow value of the ultrasonic flow meter to be calibrated on the selected drainage pipe. After the coefficients of the reference function are calibrated, the reference function in the ultrasonic flow meter to be calibrated is corrected to the calibration function, and the ultrasonic flow meter to be calibrated can be installed on the application pipeline to detect the flow in the application pipeline. This can avoid the inability to obtain the accurate flow value in the non-full pipe channel after the ultrasonic flow meter to be calibrated is installed, and the ultrasonic flow meter cannot be calibrated after installation due to the difficulty in measuring the flow in the non-full pipe channel.

[0061] Optionally, in step S8, when the flow meter is actually used, the reference function set when the flow meter is manufactured may be calibrated as the calibration function in the actual meter head or the host computer. cal .(Q raw_value ) can be the flow value calculated with the reference function f base (Q raw_value ) is linearly related, such as f cal .(Q raw_value )=γ*f base (Q raw_value Of course, in other embodiments of the present application, other linear equations may be used to calibrate the reference function, such as f cal .(Q raw_value )=γ*f base (μQ raw_value +τ). In which, the flow meter detects a signal value Q raw_value , f base (Q raw_value ) is due to f base (Q raw_value , Q stan._value ) function calculates Q stan._value value (which can be a calculated value inside the meter or a displayed value on the meter or host computer), f cal .(Q raw_value ) is due to f cal .(Q raw_value , Q stan._value ) function calculates Q stan._value Value (i.e. the display value of the meter or host computer), γ, μ and τ are correction coefficients.

[0062] On the other hand, in the production process of ultrasonic flowmeters, the differences between the electronic components and ultrasonic transducers of different ultrasonic flowmeters will also make the instrument coefficient ξ of each ultrasonic flowmeter not exactly the same. However, in steps S1-S4, by installing multiple ultrasonic flowmeters to be calibrated on multiple pipes with different cross-sections, the influence of a single ultrasonic flowmeter on the calibration data can be reduced, and the instrument coefficient tends to be averaged by curve fitting between multiple groups of data, that is:

[0063]

[0064] Where: irepresents the instrument coefficient of the ultrasonic flowmeter to be installed on each drainage pipe, N represents the number of detections (i.e., the sum of the number of ultrasonic flowmeters measured on all drainage pipes), and ξ is the averaged instrument coefficient. In steps S5-S8, a calibration function close to the actual flow rate is obtained by calibrating the reference function of an ultrasonic flowmeter to be calibrated, and the instrument coefficient of the ultrasonic flowmeter to be calibrated is compensated from the average value ξ to ξ by compensating the coefficient in the reference function. i Although two calibrations are used for a single ultrasonic flowmeter (once to obtain the reference equation and once to calibrate the coefficients of the reference equation), the calibration of the reference equation coefficients reduces the disadvantage of the reference function being too large to fit due to the direct setting of the reference function and the use of pipeline data to calibrate the reference function coefficients.

[0065] For a drainage pipe with a known cross section and material, the water cross-sectional area A is only related to the water depth h, and the water flow rate Q is only related to the flow velocity v (average velocity) and the water depth h (i.e., Q = v*A).

[0066] Instantaneous water flow: Q i =f(v,h), where when the water depth h is stable, the flow velocity v is a constant;

[0067] Accumulated traffic: Among them, Δt i Represents a time period, Q i Indicates the period of time Δt i The average water flow rate in (when Δt i When it is very short, it can be considered that the corresponding Q i is the instantaneous flow rate).

[0068] Step S2 also includes: controlling the water flow in the water main pipe, adjusting the water pressure in the pressure-stabilizing water tank, and stabilizing the water pressure in the pressure-stabilizing water tank; after the water flow pressure and flow in the drainage pipe are stable, obtaining the flow value Q of the ultrasonic flowmeter to be calibrated in the drainage pipe. raw_value , and the standard flow value Q corresponding to the standard flow meter on the water main pipe stan._value The data is obtained after the water pressure and flow rate are controlled to be stable, which can ensure the stability and reliability of the values. Of course, the same method can also be used in step S6 to ensure the stability and reliability of the acquired data.

[0069] When the water flow in the drain pipe is adjusted to be stable (fluctuating within a relatively small range), it can be The accumulated flow q in the period is used to calculate the average water flow rate during the period to reduce the error caused by water flow fluctuations or ultrasonic flowmeter fluctuations. That is, when obtaining the flow value Q of the ultrasonic flowmeter to be calibrated raw_value_i (or Qraw_value ) and standard flow value Q stan._value_i (or Q stan._value ), the influence of instantaneous fluctuation error on the calibration of the reference function can be reduced by using the average water flow value of the ultrasonic flowmeter to be calibrated during a stable period of time and the average water flow value of the standard flowmeter during a period of time.

[0070] Step S2 also includes: obtaining the flow value Q of the ultrasonic flowmeter to be calibrated raw_value is the cumulative flow rate q of the ultrasonic flowmeter to be calibrated within the time Δt raw .Calculate the average water flow value and obtain the standard flow value Q stan._value is the cumulative flow rate q measured by the standard flow meter within time Δt stan Calculate the average water flow value. That is, Q raw_value =q raw . / Δt,Q stan._value =q stan . / Δt, where q raw . Indicates the cumulative flow rate of the ultrasonic flowmeter to be calibrated within the time Δt, q stan . represents the cumulative flow rate of the standard flowmeter in the time Δt. The average water flow value is used for curve fitting to reduce the influence of the instantaneous fluctuation of the flowmeter to be calibrated, the standard flowmeter and the water flow on the accuracy of the benchmark function.

[0071] Step S6 also includes: obtaining the flow value Q of the ultrasonic flowmeter to be calibrated raw_value_i is the cumulative flow rate q of the ultrasonic flowmeter to be calibrated within the time Δt raw._i Calculate the average water flow value and obtain the standard flow value Q stan . value_i is the cumulative flow rate q measured by the standard flow meter within time Δt stan_i Calculate the average water flow value. That is, Q raw_value_i =q raw._i / Δt,Q stan._value_i =q stan._i / Δt, where q raw._i It represents the cumulative flow rate of the ultrasonic flowmeter to be calibrated within the time Δt, q stan._i It represents the cumulative flow rate of the standard flowmeter in the time Δt. The average water flow value is used for curve fitting to reduce the influence of the instantaneous fluctuation of the flowmeter to be calibrated, the standard flowmeter and the water flow on the accuracy of the benchmark function.

[0072] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for calibrating an ultrasonic flowmeter, characterized in that: An ultrasonic flowmeter calibration device is used, which includes a pressure-stabilizing water tank for providing a stable water outlet pressure, a water pipe connected to the pressure-stabilizing water tank at one end, and a plurality of drainage pipes for supporting the ultrasonic flowmeter to be calibrated, wherein the cross-sectional shapes of the plurality of drainage pipes are different, the water pipe includes a main water pipe connected to the pressure-stabilizing water tank at one end, and a plurality of branch pipes respectively connected to the drainage pipes, each of the branch pipes is connected to the main water pipe, a standard flowmeter for detecting the water flow in the main water pipe and a flow regulating valve for regulating the water flow in the main water pipe are installed on the main water pipe, and a control valve for controlling the on-off of the branch pipe is respectively installed on each of the branch pipes; The ultrasonic flowmeter calibration method comprises the following steps: S1. Installing the ultrasonic flowmeter to be calibrated on each of the drainage pipes; S2, control the water flow in the water main pipe to flow out through each of the drainage pipes in sequence, and when the water flows through each of the drainage pipes, control the water flow rate of the water main pipe, so that multiple groups of flow values ​​of each of the drainage pipes can be obtained ( , ),in is the flow value of the ultrasonic flowmeter to be calibrated, is the standard flow value corresponding to the standard flow meter on the water main; S3, according to the multiple groups in step S2 and The value of is used for curve fitting to obtain the reference function of the ultrasonic flowmeter to be calibrated ; S4. The benchmark function Implant each ultrasonic flow meter to be calibrated; After step S4, the method further includes: S5, selecting the drainage pipe with a cross section similar to that of the application pipe of the ultrasonic flowmeter to be calibrated, and installing the ultrasonic flowmeter to be calibrated on the drainage pipe; S6, controlling the water flow in the water main pipe to be discharged from the drain pipe, and controlling the water flow in the water main pipe to obtain multiple flow values ​​of the ultrasonic flowmeter to be calibrated , and the standard flow value corresponding to the standard flow meter on the water main pipe ; S7, according to each group in step S6 and The value of the benchmark function The coefficients in are compensated to obtain the calibration function of the ultrasonic flowmeter to be calibrated. ; S8, the reference function in the ultrasonic flowmeter to be calibrated Corrected to calibration function .

2. The ultrasonic flowmeter calibration method according to claim 1, characterized in that: A liquid level sensor is arranged at the bottom of the pressure-stabilizing water tank.

3. The ultrasonic flowmeter calibration method according to claim 1, characterized in that: The pressure-stabilizing water tank is connected with a water supply pipe, and a liquid level regulating valve is installed on the water supply pipe.

4. The ultrasonic flowmeter calibration method according to claim 1, characterized in that: The ultrasonic flowmeter calibration device also includes a water return component for conveying the drainage from each of the drainage pipes to the pressure-stabilizing water tank.

5. The ultrasonic flowmeter calibration method according to claim 4, characterized in that: The water return assembly comprises a collecting tank for collecting drainage from each drainage pipe, a water return pipe connecting the collecting tank and the pressure-stabilizing water tank, and a reflux pump installed on the water return pipe.

6. The ultrasonic flowmeter calibration method according to claim 5, characterized in that: The reflux pump is a variable frequency pump.

7. The ultrasonic flowmeter calibration method according to any one of claims 1 to 6, characterized in that: Step S2 also includes: controlling the water flow in the water main pipe, adjusting the water pressure in the pressure-stabilizing water tank, and stabilizing the water pressure in the pressure-stabilizing water tank; after the water flow pressure and flow in the drainage pipe are stable, obtaining the flow value of the ultrasonic flowmeter to be calibrated in the drainage pipe. , and the standard flow value corresponding to the standard flow meter on the water main pipe .

8. The ultrasonic flowmeter calibration method according to any one of claims 1 to 6, characterized in that: Step S2 also includes: obtaining the flow value of the ultrasonic flowmeter to be calibrated The ultrasonic flowmeter to be calibrated is The accumulated flow in Calculated average water flow value; obtained standard flow value The standard flow meter is used at time The accumulated flow in Calculate the average water flow value.

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