CN111380598A - Ultrasonic flowmeter calibration device and calibration method thereof - Google Patents

Abstract

An ultrasonic flowmeter calibration device and its calibration method, comprising a stabilized water tank for providing stable water outlet pressure, a water delivery pipe connected to the stabilized water tank at one end, and a plurality of drainage pipes for supporting the ultrasonic flowmeter to be calibrated, The cross-sectional shapes of the plurality of drainage pipes are different. The water delivery pipes include a water delivery main pipe connected with the stabilized water tank at one end and a plurality of branch pipes respectively connected with each drainage pipe. Each branch pipe is connected with the water delivery main pipe. A standard flow meter 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, and a control valve for controlling the on-off of the branch pipe is respectively installed on each branch pipe. The ultrasonic flowmeter calibration device and its calibration method provided by the present application use drainage pipes with different cross-sections, which reduces the difference in the calibration time of the ultrasonic flowmeters to be calibrated on different drainage pipes, and reduces the flow rate after the calibration of the ultrasonic flowmeters. detection error.

Description

An ultrasonic flowmeter calibration device and calibration method thereof

technical field

The present application belongs to the technical field of flowmeters, and more particularly, relates to an ultrasonic flowmeter calibration device and a calibration method thereof.

Background technique

In urban construction, the construction of drainage pipe network is particularly important. If the design of the drainage pipe network is unreasonable, the urban drainage efficiency will be low, which will easily lead to urban waterlogging. When designing a drainage channel, it is necessary to consider its drainage flow. Usually, a certain drainage margin is reserved, which makes the water in the drainage channel usually not full.

In order to accurately measure the drainage flow in the drainage channel, a corresponding ultrasonic flowmeter needs to be installed. 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, according to the flow value of the actual installation pipeline The benchmark function within the ultrasonic flowmeter is calibrated. However, due to the 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 difference between the reference function and the actual flow value and the signal value of the ultrasonic flowmeter to be calibrated The rules may be inconsistent, which leads to large differences in the calibration of ultrasonic flowmeters to be calibrated on different pipes, and the calibration error is large.

SUMMARY OF THE INVENTION

The purpose of this application is to provide an ultrasonic flowmeter calibration device, including but not limited to solving the problem that when the ultrasonic flowmeter calibration method in the prior art is used to calibrate the ultrasonic flowmeters to be calibrated on different pipes, there is a large difference in the calibration, And the technical problem of large calibration error.

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 stabilized water tank for providing stable water outlet pressure, a water delivery pipe connected to the stabilized water tank at one end, and A plurality of drainage pipes used to support the ultrasonic flowmeter to be calibrated, the cross-sectional shapes of the plurality of drainage pipes are different, and the water delivery pipes include a water delivery main pipe connected with the stabilized water tank at one end and a water delivery pipe connected with each of the a plurality of branch pipes connected to the drain pipe, each branch pipe is connected to the water delivery main pipe, and a standard flow meter for detecting the water flow in the water delivery main pipe and for adjusting the water delivery main pipe are installed on the water delivery main pipe A flow regulating valve for the water flow in the main water delivery pipe, and a control valve for controlling the on-off of the branch pipe is respectively installed on each of the branch pipes.

Further, the bottom of the pressurized water tank is provided with a liquid level sensor.

Further, a water supply pipe is connected to the pressure-stabilized water tank, and a liquid level regulating valve is installed on the water supply pipe.

Further, the ultrasonic flowmeter calibration device further includes a water return component for conveying the drainage of each of the drainage pipes to the stabilized water tank.

Further, the water return assembly includes a collection tank for collecting the drainage of each of the drainage pipes, a return pipe connecting the collection tank and the pressure-stabilized water tank, and a return pump installed on the return pipe.

Further, the return pump is a variable frequency pump.

The present application further provides a method for calibrating an ultrasonic flowmeter. The ultrasonic flowmeter to be calibrated is calibrated using the ultrasonic flowmeter calibration device described in any of the above embodiments, and the ultrasonic flowmeter calibration method includes the following steps:

S1. Install the ultrasonic flowmeter to be calibrated on each of the drainage pipes;

S2. Control the water flow in the water delivery main pipe to flow out through each of the drainage pipes in turn, and when the water flow flows through each of the drainage pipes, control the water flow of the water delivery main pipe, and then each of the drainage pipes can be obtained. Multiple groups of flow values (Q _{raw_value} , Q _{stan._value} ), wherein Q _{raw_value} is the flow value of the ultrasonic flowmeter to be calibrated, and Q _{stan._value} is the standard flow value corresponding to the standard flowmeter on the water main pipe;

S3, perform curve fitting according to the values of multiple groups of Q _{raw_value} and Q _{stan._value} in step S2, obtain the reference function f _base (Q _{raw_value} , Q _{stan._value} ) of the ultrasonic flowmeter to be calibrated;

S4, implant the reference function f _base (Q _{raw_value} , Q _{stan._value} ) into each ultrasonic flowmeter to be calibrated.

Further, after step S4, it also includes:

S5. Select the drainage pipe with a similar cross section to the application pipeline of the ultrasonic flowmeter to be calibrated, and install the ultrasonic flowmeter to be calibrated on the drainage pipe;

S6. Control the water flow in the water delivery main pipe to be discharged from the drain pipe, and control the water flow in the water delivery main pipe to obtain multiple flow values Q _{raw_value_i} of the ultrasonic flowmeter to be calibrated and the water delivery main pipe The standard flow value Q _{stan._value_i} corresponding to the upper standard flow meter;

S7, according to the values of each group of Q _{raw_value_i} and Q _{stan._value_i} in step S6, the coefficients in the reference function f _base (Q _{raw_value} , Q _{stan._value} ) are compensated to obtain the calibration function of the ultrasonic flowmeter to be calibrated f _cal .(Q _{raw_value} , Q _{stan._value} );

S8. Correct the reference function f _base (Q _{raw_value} , Q _{stan._value} ) in the ultrasonic flowmeter to be calibrated into a calibration function f _cal . (Q _{raw_value} , Q _{stan._value} ).

Further, in step S2, it also includes: controlling the water flow in the water delivery main pipe, adjusting the water pressure in the stabilized water tank, so that the water pressure in the stabilized water tank is stable; the water flow pressure in the drain pipe and After the flow is stable, the flow value Q _{raw_value_i} of the ultrasonic flowmeter to be calibrated of the drain pipe and the standard flow value Q _{stan._value_i} corresponding to the standard flowmeter on the water main pipe are obtained.

Further, in step S2, it also includes: the obtained flow value Q _{raw_value} of the ultrasonic flowmeter to be calibrated is the average water flow value calculated by the cumulative flow q _raw . of the ultrasonic flowmeter to be calibrated within time Δt; obtain The standard flow value of Q _{stan._value} is the average water flow value calculated from the cumulative flow q _stan of the standard flow meter in time Δt.

The ultrasonic flowmeter calibration device and its calibration method provided by the present application use a stabilized water tank to provide a stable water delivery pressure, so that a stable water flow can be obtained in each drainage pipe; The non-full flow data of the cross-section drainage pipe, and then calculate the reference function suitable for a variety of different cross-section drainage pipes, so as to realize the reference function setting of the ultrasonic flowmeter to be calibrated, so that the reference function in the ultrasonic flowmeter to be calibrated can be applied to different The cross-sectional drainage pipe reduces the difference in the calibration time of the ultrasonic flowmeters to be calibrated on different drainage pipes, and reduces the error of the flow detection after the calibration of the different ultrasonic flowmeters.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present application more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only for the present application. In some embodiments, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without any creative effort.

1 is a schematic structural diagram of an ultrasonic flowmeter calibration device provided in Embodiment 1 of the application;

2 is a schematic structural diagram of an ultrasonic flowmeter calibration device provided in Embodiment 2 of the application;

3 is a schematic structural diagram of an ultrasonic flowmeter calibration device provided in Embodiment 3 of the application;

FIG. 4 is a schematic diagram of water flow in Embodiment 1 of the present application.

Among them, each reference sign in the figure:

11—stabilized water tank, 21—water delivery pipe, 21a—water delivery main pipe, 21b—branch pipe, 23—standard flowmeter, 24—flow regulating valve, 25—control valve, 31—drainage pipe, 32—ultrasonic to be calibrated Flowmeter, 41—water supply pipe, 42—liquid level control valve, 51—collection tank, 52—return water pipe, 53—return pump.

Detailed ways

The following describes in detail the embodiments of the present application, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary, and are intended to be used to explain the present application, but should not be construed as a limitation to the present application.

In the description of this application, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", The orientation or positional relationship indicated by "horizontal", "top", "bottom", "inside", "outside", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than An indication or implication that the referred device or element must have, be constructed, and operate in a particular orientation is not to be construed as a limitation on the present application.

In addition, the terms "first" and "second" are only used for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined as "first" or "second" may expressly or implicitly include one or more of that feature. In the description of the present application, "plurality" means two or more, unless otherwise expressly and specifically defined.

In this application, unless otherwise expressly specified and limited, the terms "installed", "connected", "connected", "fixed" and other terms should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection , or integrated; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of the two elements or the interaction relationship between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific situations.

Please refer to FIG. 1 to FIG. 4 together, and now the ultrasonic flowmeter calibration device provided by the present application will be described. The ultrasonic flowmeter calibration device includes a stabilized water tank 11 , a water delivery pipe 21 and a plurality of drainage pipes 31 . One end of the water delivery pipe 21 is connected with the stabilized water tank 11, and the other end of the water delivery pipe 21 is connected with each drain pipe 31; Either drain 31. The water delivery pipe 21 includes a water delivery main pipe 21a and a plurality of branch pipes 21b. One end of the water delivery main pipe 21a is connected to the stabilized water tank 11, each branch pipe 21b is respectively connected to each drain pipe 31, and each branch pipe 21b is connected to the water delivery main pipe 21a. connect. The water main pipe 21a is provided with a standard flow meter 23 and a flow regulating valve 24. The standard flow meter 23 is used to detect the flow in the water main pipe 21a, and the flow regulating valve 24 is used to adjust the water flow in the water main pipe 21a. A control valve 25 is installed on each branch pipe 21b respectively, and the control valve 25 is used to control the on-off of the branch pipe 21b, and each drain pipe 31 can support the ultrasonic flowmeter 32 to be calibrated for installation. Wherein, the ultrasonic flow meters 32 to be calibrated are of the same model. The use of the stabilized 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; For the non-full flow data under stable water flow, after curve fitting the obtained multiple sets of data of the drainage pipes 31 with different cross-sections, the reference function between the standard flow rate and the displayed value of the ultrasonic flowmeter 32 to be calibrated can be obtained. Since the benchmark function uses data obtained from drain pipes 31 with different cross-sections, its benchmark function has wider adaptability. There are certain differences in the real flow of the drain pipe, but the displayed value can keep consistent with the real flow law of various cross-section drain pipes. Using different cross-section drain pipes 31 for calibration to obtain the reference function can reduce the difference between the reference function and different cross-section drain pipes 31, and when calibrating the coefficients of the reference function, it can reduce the difference caused by the reference function. The error is reduced, the calibration error is reduced, and the detection accuracy after calibration of the ultrasonic flowmeter 32 to be calibrated is improved.

For example, when performing curve fitting on three sets of data obtained from a drain pipe 31, using exponential relationship, linear relationship, logarithmic relationship or polynomial relationship, etc., different functional relationships can be obtained, among which three sets of data must be satisfied. The trinomial function of ; when there are exactly three sets of data in a linear relationship, there are at least two functions that can completely fit the three sets of data. When fitting the six sets of data obtained from two different drain pipes 31 , it is assumed that the standard flow values in the three sets of data of the two drain pipes 31 are respectively equal, but the corresponding display values in the two sets of data may exist At this time, the functions obtained by fitting the three sets of data curves of any drain pipe 31 are quite different from the functions obtained by curve fitting of the other drain pipe 31, so that when the ultrasonic flowmeter 32 to be calibrated is Using the reference function obtained by fitting the data curve of the first type of drain pipe 31, when it is installed on the second type of drain pipe 31, the error will be very large, and it may even lead to the inability to calibrate the ultrasonic wave through the data obtained from the second type of drain pipe. flowmeter to reduce this error. The main reason for this difference is the difference in the cross-sectional shape of the drain pipe. 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 of the three sets of data obtained in any drain pipe 31, the correlation coefficient of the function relative to the six sets of data is higher than that of any one. The correlation coefficient of the three sets of data fitting functions on one drain pipe 31 is larger than that of the six groups of data, that is, it can make the data of various drain pipes 31 closer to the obtained functions. This 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 drainage pipe 31, the data obtained from the drainage pipe 31 can be used to further perform the ultrasonic flowmeter 32. For calibration, since the obtained data is relatively close 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 . In this way, the problem of the difference of the reference equation obtained by using a single-shaped cross-section drain pipe in the existing calibration method is avoided.

Further, the drainage pipe 31 includes a trapezoidal drainage pipe 31 having a trapezoidal cross section. Trapezoid is a common cross-sectional shape of pipes. The trapezoidal cross-section drainage pipe 31 can correspond to common trapezoidal cross-section pipes and reduce the calibration error of ultrasonic flowmeters installed on trapezoidal cross-section pipes.

Further, the drainage pipe 31 includes a circular drainage pipe 31 with a circular cross-section. The circular pipe is a common cross-sectional shape of pipes, and the drainage pipes 31 with a circular cross-section can correspond to common circular cross-sectional pipes. Reduces calibration errors for ultrasonic flowmeters installed on circular cross-section conduits.

Further, the drainage pipe 31 includes a trapezoidal drainage pipe 31 with a trapezoidal cross-section and a circular drainage pipe 31 with a circular cross-section. This can not only satisfy the calibration of pipes with common cross-sectional shapes, but also apply to the calibration cross-sections of ultrasonic flowmeters on pipes with similar cross-sectional shapes of the two pipes. For example, the bottom is horizontal, and the two sides are in the shape of a paraboloid or a circular arc.

Further, the bottom of the stabilized water tank 11 is provided with a liquid level sensor, and the setting of the liquid level sensor is convenient to control the liquid level in the stabilized water tank 11, so as to avoid the water flow in the water delivery main pipe 21a due to the fluctuation of the liquid level in the stabilized water tank 11. Shocks are generated, causing fluctuations in water pressure and flow.

Further, a water supply pipe 41 is connected to the stabilized water tank 11 , and the water supply pipe 41 can supply water to the stabilized water tank 11 to control the stability of the pressure at the connection position between the stabilized water tank 11 and the water pipe 21 . A liquid level regulating valve 42 is installed on the water supply pipe 41 to adjust the amount of water injected by the water supply pipe 41 into the stabilized water tank 11 . In this way, the water pressure in the calibration process can be controlled, so that the ultrasonic flowmeter to be measured and the standard flowmeter 23 can be under the same pressure, and the pressure fluctuation can be avoided between the original flow value of the ultrasonic flowmeter to be calibrated 32 and the standard detected by the standard flowmeter 23 The flow value interferes and affects the accuracy of the calibration result. On the other hand, the water supply pipe 41 can supply water to the interior of the stabilized water tank 11 when there is no water or lack of water.

Further, the ultrasonic flowmeter calibration device further includes a water return component, and the return water component is used for conveying the drainage of each drainage pipe 31 to the stabilized water tank 11 . In this way, the recycling of water in the ultrasonic flowmeter calibration device can be realized. Moreover, when the return water assembly and the replenishment pipe 41 cooperate with each other, the size of the replenishment pipe can be reduced, so as to precisely control the replenishment amount of the stabilized water tank 11 and realize the fine adjustment of the liquid level in the stabilized water tank 11; The assembly makes the water flow more stable throughout the ultrasonic flowmeter calibration device.

Further, please refer to FIG. 2 , FIG. 3 and FIG. 4 together, as a specific implementation of the ultrasonic flowmeter calibration device provided by the embodiment of the present application, the return water assembly includes a collection tank 51 , a return water pipe 52 and a return pump 53 . The collection tank 51 is used to collect the drainage of each drain pipe 31, the return pipe 52 is connected to the collection tank 51 and the stabilized water tank 11, and the return pump 53 is installed on the return pipe 52 to transport the water in the collection tank 51 to the stabilized water tank 52. Jug 11. When collecting the drainage in the drainage pipe 31 , the collecting tank 51 can also eliminate the pulse in the water flow, so as to prevent the pulse in the water flow from impacting the water flow in the return pipe 52 and affecting the stability of the stabilized water tank 11 .

Specifically, the stabilized water tank 11 can be a sealed tank, and a compressed air pipe and an exhaust pipe are connected to the top of the sealed tank, and the compressed air is fed to the top of the stabilized water tank 11; a pressure is set on the top of the stabilized water tank 11 The sensor, according to the pressure value of the stabilized water tank 11, feeds compressed air to the top of the stabilized water tank 11, or releases the compressed air, so that the outlet water pressure of the stabilized water tank 11 remains stable; The liquid level regulating valve 42 maintains the stability of the liquid level in the stabilized water tank 11 . On the one hand, the use of compressed air can eliminate the impact on the internal water pressure caused by the water flow entering the stabilized water tank 11, and reduce the fluctuation of its internal water pressure and water flow; on the other hand, by using compressed air, the stabilized water tank can be adjusted according to needs. 11, which is beneficial to reduce the volume of the stabilized water tank 11.

Of course, the pressure-stabilized water tank 11 can also be an overflow tank with an opening at the top, and the liquid level and pressure inside the pressure-stabilized water tank 11 can be kept stable through overflow.

Specifically, the return pump 53 is a variable frequency pump, and the use of the variable frequency pump can adjust the flow of the return water, so that the water flow can maintain a stable circulation between the return tank and the stabilized water tank 11 .

Preferably, each drainage pipe 31 is made of concrete. In this way, it can be ensured that the material of the drain pipe 31 is basically the same as that of the actually installed pipe canal, and errors caused by the material of the pipe canal after the installation of the to-be-calibrated ultrasonic flowmeter 32 can be avoided.

The present application also provides a method for calibrating an ultrasonic flowmeter. The ultrasonic flowmeter to be calibrated is calibrated using the ultrasonic flowmeter calibration device described in any of the above embodiments, and the calibration method includes the following steps:

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

S2. Control the water flow in the water delivery main pipe to flow out through each of the drainage pipes in turn, and when the water flow flows through each of the drainage pipes, control the water flow of the water delivery main pipe, and then each of the drainage pipes can be obtained. The multiple sets of flow values (Q _{raw_value} , Q _{stan._value} ), wherein Q _{raw_value} is the flow value (detection signal value) of the ultrasonic flowmeter to be calibrated, and Q _{stan._value} is the corresponding standard flowmeter on the water main pipe The standard flow value of ;

S3, perform curve fitting according to the values of multiple groups of Q _{raw_value} and Q _{stan._value} in step S2, obtain the reference function f _base (Q _{raw_value} , Q _{stan._value} ) of the ultrasonic flowmeter to be calibrated;

S4, implant the reference function f _base (Q _{raw_value} , Q _{stan._value} ) into each ultrasonic flowmeter to be calibrated.

Using a plurality of drainage pipes 31 with different cross-sections, multiple sets of flow values Q _{raw_value} and corresponding standard flow values Q _{stan._value} of the ultrasonic flowmeters 32 to be calibrated for the drainage pipes 31 with different cross-sections can be obtained. When performing curve fitting, the obtained benchmark function can be adapted to measure the flow rate of drain pipes 31 with different cross-sections. The benchmark function here is that the ultrasonic flowmeter can be implanted in the ultrasonic flowmeter when it is produced, so that when the ultrasonic flowmeter is installed in the pipeline of a specific application, it can be further based on the flow data on the pipeline and the detection of the ultrasonic flowmeter. The numerical value is used to further calibrate the coefficient of the reference function f _base (Q _{raw_value} , Q _{stan._value} ) in the ultrasonic flowmeter, thereby reducing the error of the ultrasonic flowmeter. Since the reference equation used in the ultrasonic flowmeter calibration method is derived from curve fitting of different drainage pipes, the ultrasonic flowmeter is prevented from being affected by the difference in the depth and flow velocity of a single drainage pipe, so that the reference equation can be applied to other shapes of cross-sections. The error is so large that even a calibration by applying the actual flow on the pipe cannot correct for the error introduced by the reference function.

得到待标定超声波流量计的基准函数f_base(Q_{raw_value}，Q_{stan._value})的系数k₀、k₁和k₂。当然地，在本申请的其它实施例中，也可以是采用其它方式进行拟合，如利用公式Q_{stan._value_i}＝k₀+k₁ln(Q_{raw_value_i})+k₂ln²(Q_{raw_value_i})来求解各系数。Optionally, in step S3, the

The coefficients k ₀ , k ₁ and k ₂ of the reference function f _base (Q _{raw_value} , Q _{stan._value} ) of the ultrasonic flowmeter to be calibrated are obtained. Certainly, in other embodiments of the present application, other methods may also be used for fitting, for example, using the formula Q _{stan._value_i} =k ₀ +k ₁ ln(Q _{raw_value_i} )+k ₂ ln ² (Q _{raw_value_i} ) to Solve for each coefficient.

Further, after step S4, it also includes:

S5. Select the drainage pipe with a similar cross section to the application pipeline of the ultrasonic flowmeter to be calibrated, and install the ultrasonic flowmeter to be calibrated on the drainage pipe;

S6. Control the water flow in the water delivery main pipe to be discharged from the drain pipe, and control the water flow in the water delivery main pipe to obtain multiple flow values Q _{raw_value_i} of the ultrasonic flowmeter to be calibrated and the water delivery main pipe The standard flow value Q _{stan._value_i} corresponding to the upper standard flow meter;

S7, according to the values of each group of Q _{raw_value_i} and Q _{stan._value_i} in step S6, the coefficients in the reference function f _base (Q _{raw_value} , Q _{stan._value} ) are compensated to obtain the calibration function of the ultrasonic flowmeter to be calibrated f _cal .(Q _{raw_value} , Q _{stan._value} );

S8. Correct the reference function f _base (Q _{raw_value} , Q _{stan._value} ) in the ultrasonic flowmeter to be calibrated into a calibration function f _cal . (Q _{raw_value} , Q _{stan._value} ).

In the above steps S5-S8, by selecting a drainage pipe with a similar cross section to the application pipeline of the ultrasonic flowmeter to be calibrated, the ultrasonic flowmeter to be calibrated is installed on the drainage pipe to simulate the actual installation pipeline of the ultrasonic flowmeter to be calibrated . The coefficients of the reference function f _base (Q _{raw_value} , Q _{stan._value} ) implanted in the ultrasonic flowmeter in step S4 are further calibrated by using multiple sets (Q _{raw_value_i} , Q _{stan._value_i} ) obtained on the drain pipe, Further, the error between the displayed value of the ultrasonic flowmeter to be calibrated and the actual value is reduced. Among them, Q _{raw_value_i} represents the flow value of the ultrasonic flowmeter to be calibrated on the selected drain pipe, and Q _{stan._value_i} represents the standard flow value corresponding to the standard flowmeter, which corresponds to the standard flowmeter at the same time (or within the same period of time). The standard flow value and the flow value of the ultrasonic flowmeter to be calibrated on the selected drain. After the coefficient of the reference function is calibrated, the reference function in the ultrasonic flowmeter to be calibrated is corrected to the calibration function, and the ultrasonic flowmeter to be calibrated can be installed on the application pipeline to detect the flow in the application pipeline. In this way, it can be avoided that the accurate flow value in the non-full pipe and canal cannot be obtained after the ultrasonic flowmeter to be calibrated is installed, and the installed ultrasonic flowmeter cannot be calibrated.

Optionally, in step S8, when the flowmeter is actually used, the reference function set during the manufacture of the flowmeter may be calibrated as a calibration function in the actual meter head or the upper computer. The actual flow rate f _cal .(Q _{raw_value} ) displayed by the actual header or the host computer can be linearly related to the flow value f _base (Q _{raw_value} ) calculated by the benchmark function, such as f _cal .(Q _{raw_value} )=γ*f _base (Q _{raw_value )} )Wait. Certainly, in other embodiments of the present application, other linear equations may also be used to calibrate the reference function, for example, f _cal .(Q _{raw_value} )=γ*f _base (μQ _{raw_value} +τ). Among them, the signal value Q _{raw_value} is detected by the flowmeter, and f _base (Q _{raw_value} ) is the Q _{stan._value} value calculated by the f _base (Q _{raw_value} , Q _{stan._value} ) function (which can be used as a calculation inside the meter header). value, it can also be the display value as the header or the host computer), f _cal .(Q _{raw_value} ) is the Q _{stan._value} value calculated by the f _cal .(Q _{raw_value} , Q _{stan._value} ) function (that is, the header or the displayed value of the host computer), γ, μ and τ are correction coefficients.

On the other hand, in the production process of ultrasonic flowmeters, the difference 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 a plurality of ultrasonic flowmeters to be calibrated on a plurality of pipes with different cross-sections, the influence of a single ultrasonic flowmeter on the calibration data can be reduced, and through curve fitting between multiple sets of data , which in turn makes the meter coefficients tend to be averaged, namely:

Among them: ξ _i represents the meter coefficient of the ultrasonic flowmeter to be installed on each drain pipe, N represents the number of detections (that is, the sum of the measurement times of the ultrasonic flowmeter on all the drain pipes), and ξ is the averaged meter coefficient. In steps S5-S8, a calibration function similar to the actual flow rate is obtained by calibrating the reference function of an ultrasonic flowmeter to be calibrated, and the calibration function of the ultrasonic flowmeter to be calibrated is realized by compensating the coefficients in the reference function. The meter coefficient is compensated by the mean value ξ to ξ _i . Although for a single ultrasonic flowmeter, two calibrations are used (once to obtain the reference equation, and once to calibrate the coefficients of the reference equation), but through the calibration of the reference equation coefficients, it reduces the need to directly set the reference function, using The use of conduit data to calibrate the benchmark function coefficients has the disadvantage that the deviation of the benchmark function is too large and cannot be fitted.

For drainage pipes with known cross-sections and materials, the water cross-sectional area A is only related to the water depth h, and the water flow Q is only related to the flow velocity v (average velocity) and the water depth h (ie, Q=v*A), that is, the

Instantaneous water flow: Q _i =f(v, h), where, when the water depth h is stable, the flow velocity v is a fixed value;

其中，Δt_i表示一个时间段，Q_i表示该段时间Δt_i内的平均水流量(当Δt_i极短时，可以认为对应的Q_i即为瞬时流量)。Accumulate flow:

Among them, Δt _i represents a time period, and Q _i represents the average water flow in this period of time Δt _i (when Δt _i is extremely short, it can be considered that the corresponding Qi _i is the instantaneous flow rate).

Step S2 also includes: controlling the water flow in the water main pipe, adjusting the water pressure in the stabilized water tank to stabilize the water pressure in the stabilized water tank; after the water flow pressure and flow in the drain pipe are stabilized , to obtain the flow value Q _{raw_value} of the ultrasonic flowmeter to be calibrated of the drain pipe, and the standard flow value Q _{stan._value} corresponding to the standard flowmeter on the water main pipe. The data is obtained after controlling the water flow pressure and flow 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.

内的积累流量q来计算该段时间内的平均水流量，以减小由于水流波动或者超声波流量计波动带来的误差。即，在获取待标定超声波流量计的流量值Q_{raw_value_i}(或Q_{raw_value})和标准流量值Q_{stan._value_i}(或Q_{stan._value})时，采用待标定超声波流量计一段稳定时间内的平均水流量值、以及标准流量计一段时间内的平均水流量值，可以减小由于瞬时波动误差对基准函数校准产生的影响。When the water flow in the drain pipe is adjusted to be stable (fluctuates in a relatively small amplitude), it can pass a period of time

The accumulated flow q within this period is used to calculate the average water flow during this period, so as to reduce the error caused by the fluctuation of the water flow or the fluctuation of the ultrasonic flowmeter. That is, when obtaining the flow value Q _{raw_value_i} (or Q _{raw_value} ) and the standard flow value Q _{stan._value_i} (or Q _{stan._value} ) of the ultrasonic flowmeter to be calibrated, the average water flow rate of the ultrasonic flowmeter to be calibrated for a stable period of time is used value, and the average water flow value of the standard flowmeter over a period of time, which can reduce the impact of the instantaneous fluctuation error on the calibration of the reference function.

In step S2, it also includes: the obtained flow value Q _{raw_value} of the ultrasonic flowmeter to be calibrated is the average water flow value calculated by the cumulative flow q _raw . of the ultrasonic flowmeter to be calibrated within the time Δt, and the obtained standard flow value Q _{stan._value} is the average water flow value calculated from the cumulative flow q _stan of the standard flow meter during time Δt. That is, Q _{raw_value} = q _raw ./Δt, Q _{stan._value} = q _stan ./Δt, where q _raw . represents the cumulative flow of the ultrasonic flowmeter to be calibrated within the time Δt, and q _stan . represents the standard flow meter at The corresponding cumulative flow during time Δt. Using the average water flow value for curve fitting can reduce the influence of the flowmeter to be calibrated, the standard flowmeter and the instantaneous fluctuation of the water flow on the accuracy of the reference function.

Step S6 also includes: the obtained flow value Q _{raw_value_i} of the ultrasonic flowmeter to be calibrated is the average water flow value calculated by the cumulative flow q _{raw._i} of the ultrasonic flowmeter to be calibrated within time Δt, and the obtained standard flow value Q _stan . _{value_i} is the average water flow value calculated from the cumulative flow q _{stan_i} of the standard flow meter in time Δt. That is, Q _{raw_value_i} =q _{raw._i} /Δt, Q _{stan._value_i} =q _{stan._i} /Δt, where q _{raw._i} represents the cumulative flow of the ultrasonic flowmeter to be calibrated within time Δt, and q _{stan._i} represents The accumulated flow corresponding to the standard flow meter in time Δt. Using the average water flow value for curve fitting can reduce the influence of the flowmeter to be calibrated, the standard flowmeter and the instantaneous fluctuation of the water flow on the accuracy of the reference function.

The above descriptions are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection of the present application. within the range.

Claims (10)

1. An ultrasonic flowmeter calibration device which characterized in that: the water delivery pipe comprises a pressure stabilizing water tank, a water delivery pipe and a plurality of drainage pipes, wherein the pressure stabilizing water tank is used for providing stable water outlet pressure, one end of the water delivery pipe is connected with the pressure stabilizing water tank, the drainage pipes are used for supporting an ultrasonic flowmeter to be calibrated, the cross section shapes of the drainage pipes are different, the water delivery pipe comprises a water delivery main pipe and a plurality of branch pipes, one end of each branch pipe is connected with the pressure stabilizing water tank, the branch pipes are respectively connected with the water delivery main pipe, the water delivery main pipe is provided with a standard flowmeter used for detecting the water flow in the water delivery main pipe and a flow regulating valve used for regulating the water flow in the water delivery main pipe, and each branch pipe is respectively provided with a control valve used for controlling.

2. An ultrasonic flow meter calibration apparatus as claimed in claim 1, wherein: and a liquid level sensor is arranged at the bottom of the pressure stabilizing water tank.

3. An ultrasonic flow meter calibration apparatus as claimed in claim 1, wherein: and the pressure stabilizing water tank is connected with a water replenishing pipe, and the water replenishing pipe is provided with a liquid level regulating valve.

4. An ultrasonic flow meter calibration apparatus as claimed in claim 1, wherein: the calibration device of the ultrasonic flowmeter further comprises a water return assembly used for conveying the drainage water of each drainage pipe to the pressure stabilizing water tank.

5. An ultrasonic flow meter calibration apparatus according to claim 4, wherein: the water return component comprises a collecting tank used for collecting water drained by each drain pipe, a water return pipe connected with the collecting tank and the pressure stabilizing water tank, and a reflux pump installed on the water return pipe.

6. An ultrasonic flow meter calibration apparatus as claimed in claim 5, wherein: the reflux pump is a variable frequency pump.

7. A calibration method of an ultrasonic flowmeter is characterized by comprising the following steps: the ultrasonic flow meter calibration device as claimed in any one of claims 1 to 6 is used for calibrating the ultrasonic flow meter to be calibrated, and the ultrasonic flow meter calibration method comprises the following steps:

s1, mounting the ultrasonic flow meter to be calibrated on each water drainage pipe;

s2, controlling the water flow in the water delivery main pipe to flow out through the water discharge pipes in sequence, and controlling the water flow of the water delivery main pipe when the water flow flows through the water discharge pipes, so that a plurality of groups of flow rate values (Q) of the water discharge pipes can be obtained_{raw_value}，Q_{stan_value}) Wherein Q is_{raw_value}For the flow value, Q, of the ultrasonic flowmeter to be calibrated_{stan._value}The standard flow value is corresponding to a standard flow meter on the water delivery main pipe;

s3, according to the multiple groups of Q in the step S2_{raw_value}And Q_{stan._value}The value of the reference function f is subjected to curve fitting to obtain a reference function f of the ultrasonic flowmeter to be calibrated_base(Q_{raw_value}，Q_{stan._value})；

S4, converting the reference function f_base(Q_{raw_value}，Q_{stan._value}) Implanting each ultrasonic flowmeter to be calibrated.

8. An ultrasonic flow meter calibration method according to claim 7, wherein: further included after step S4 is:

s5, selecting the drain pipe which is close to the cross section of the application pipeline of the ultrasonic flowmeter to be calibrated, and installing the ultrasonic flowmeter to be calibrated on the drain pipe;

s6, controlling the water flow in the water delivery main pipe to be discharged through the water discharge pipe, and controlling the water flow in the water delivery main pipe to obtain a plurality of flow values Q of the ultrasonic flowmeter to be calibrated_{raw_value_i}And a standard flow value Q corresponding to a standard flow meter on the water delivery main pipe_{stan._value_i}；

S7, according to each group Q in the step S6_{raw_value_i}And Q_{stan._value_i}To the reference function f_base(Q_{raw_value}，Q_{stan._value}) To obtain a calibration function f of the ultrasonic flow meter to be calibrated_cal.(Q_{raw_value}，Q_{stan._value})；

S8, calibrating the reference function f in the ultrasonic flowmeter to be calibrated_base(Q_{raw_value}，Q_{stan._value}) Correction to a calibration function f_cal.(Q_{raw_value}，Q_{stan._value})。

9. An ultrasonic flow meter calibration method according to claim 7, wherein: step S2 further includes: controlling the water flow in the water delivery main pipe, and adjusting the water pressure in the pressure stabilizing water tank to stabilize the water pressure in the pressure stabilizing water tank; after the water flow pressure and the flow in the drain pipe are stable, acquiring a flow value Q of the ultrasonic flowmeter to be calibrated of the drain pipe_{raw_value}And a standard flow value Q corresponding to a standard flow meter on the water delivery main pipe_{stan._value}。

10. An ultrasonic flow meter calibration method according to claim 7, wherein: step S2 further includes: obtaining the flow value of the ultrasonic flowmeter to be calibratedQ_{raw_value}For the cumulative flow q of the ultrasonic flowmeter to be calibrated in the time delta t_raw.A calculated average water flow value; acquired standard flow value Q_{stan._value}Is the cumulative flow q of a standard flowmeter in time delta t_stanCalculated average water flow value.

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