Flow measurement method of external clamping type ultrasonic flowmeter using synchronous acquisition mode

Abstract

The invention provides a flow measurement method of an external clamping type ultrasonic flowmeter using a synchronous acquisition mode, which comprises the following steps of: simultaneously driving an upstream transducer and a downstream transducer to transmit signals by current signals from a function generator, and recording received signals of the transducers on the same time window; after ultrasonic signals synchronously collected by the transducer are subjected to time domain and frequency domain analysis, filtering processing and amplification processing, a function generator is used for converting and outputting square waves, and then the square waves are output to different channels after being digitalized through a multi-channel oscilloscope; by analyzing the digital square waves, ultrasonic forward and reverse flow propagation time and time difference are calculated, and then the flow is calculated by combining a time difference method measurement principle with measurement pipeline section parameters. According to the external clamping type ultrasonic flowmeter, an active synchronous acquisition mode is used, the two transducers are driven at the same time and receive signals, ultrasonic waves pass through fluid with the same temperature and flow profile, and therefore the time difference measurement deviation and the flow calculation error of the external clamping type ultrasonic flowmeter are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of clamp-on ultrasonic flowmeter measurement, and in particular to a flow measurement method of a clamp-on ultrasonic flowmeter using a synchronous acquisition mode. Background Art

[0002] The clamp-on ultrasonic flowmeter is light, compact, easy to carry, and can measure directly without contact with the medium. It is widely used in the field of industrial measurement. The clamp-on ultrasonic flowmeter adopts the time difference measurement principle, that is, two ultrasonic transducers are used to transmit and receive signals upstream and downstream along the flow direction of the fluid, and the flow rate of the measured fluid is calculated by measuring the time difference between ultrasonic pulses sent in opposite directions. The accuracy of ultrasonic propagation time measurement is the main factor affecting the measurement performance of the time difference flowmeter.

[0003] When the flow rate through the pipeline is constant, the ultrasonic propagation time difference measured by the clamp-on ultrasonic flowmeter should also remain constant. However, in practice, there are different factors that cause the ultrasonic propagation time difference to fluctuate, which in turn causes deviations in the flow measurement results. Among them, the fluctuation of the ultrasonic propagation velocity in the fluid, the flow field and flow velocity changes between the upstream and downstream of the ultrasound are important sources of deviation. The ultrasonic propagation velocity usually depends on the temperature and pressure of the fluid, but usually the change in ultrasonic propagation velocity caused by pressure fluctuations is small, and temperature is the main factor causing the fluctuation of ultrasonic propagation velocity. For example, the temperature fluctuation of the gas may be caused by the introduction of the air / water system or the heat transfer through the pipe wall, and the clamp-on ultrasonic flowmeter usually uses the constant temperature measured by the thermocouple as the input value, which will ignore the temperature changes that may exist between the upstream and downstream transducers, thereby introducing measurement errors. Studies have shown that for natural gas flowing in the pipe, a temperature change of only 1°C between the upstream and downstream ultrasonic pulses can lead to a time difference measurement error of microseconds, which corresponds to about 0.1m 3 / min level flow measurement error, and because the ultrasonic propagation time difference is proportional to the ultrasonic propagation path length, the error caused by temperature changes in the fluid will be more significant for pipes with larger diameters. For another example, during ultrasonic measurement, when the fluid flow field is unstable, the flow profile changes when the upstream and downstream transducers transmit and receive ultrasonic signals, which will inevitably lead to errors in the measurement of the time difference.

[0004] The above factors that cause measurement errors can all be attributed to the sequential data acquisition mode adopted by the external clamp-on ultrasonic flowmeter, that is, the upstream transducer is driven to generate and transmit a signal, and then after the downstream transducer receives the signal, the downstream transducer is driven and sends ultrasound in the opposite direction. In this mode, when there is a slight temperature or flow field change between the two collected signals, it will cause a deviation in the ultrasonic propagation time difference, resulting in an error in the calculated flow rate. Summary of the invention

[0005] In view of the technical problem that the existing clamp-on ultrasonic flowmeter adopts a sequential data acquisition mode, in which, when there is a slight temperature or flow field change between the two collected signals of the fluid, it will cause an ultrasonic propagation time difference deviation, thereby causing an error in the calculated flow rate, the present invention provides a flow measurement method of an external clamp-on ultrasonic flowmeter using a synchronous acquisition mode. The method uses an active synchronous acquisition mode to allow two transducers to be driven and receive signals at the same time, so that ultrasound passes through a fluid with the same temperature and flow profile, thereby reducing the time difference measurement deviation and flow calculation error of the external clamp-on ultrasonic flowmeter.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A flow measurement method using a clamp-on ultrasonic flow meter in a synchronous acquisition mode, comprising:

[0008] The transducers of the two external clamp-on ultrasonic flow meters arranged in sequence along the flow direction of the fluid in the pipeline are driven and transmitted simultaneously by the sinusoidal current signal from the function generator, and the received signals of the two transducers are recorded in the same time window;

[0009] Perform time domain analysis and frequency domain analysis on the ultrasonic signals synchronously collected and received by the upstream and downstream transducers;

[0010] Using filters to filter the signals after time domain analysis and frequency domain analysis;

[0011] Amplify the filtered signal on two channels of the signal amplifier respectively;

[0012] Use a function generator to convert the amplified signal into a square wave output, and then use a multi-channel oscilloscope to digitize the square wave, and then output the captured signal, i.e., the digitized square wave, on different channels;

[0013] By analyzing the digitized square wave, the ultrasonic propagation reference signal and echo signal characteristics are analyzed based on the cross-correlation method, curve fitting method or threshold method, so as to calculate the ultrasonic forward and reverse flow propagation time and time difference in the synchronous acquisition mode, and then calculate the fluid velocity and flow in the pipeline through the time difference measurement principle of the external clamp-on ultrasonic flowmeter combined with the measurement of the pipeline cross-sectional parameters.

[0014] Furthermore, the sinusoidal current signal of the function generator is specifically a 12V sinusoidal current signal driven at a full-thickness resonance frequency of the piezoelectric element of 6MHz.

[0015] Furthermore, the digitized square wave is analyzed, and the ultrasonic propagation reference signal and echo signal characteristics are analyzed based on the cross-correlation method, the curve fitting method or the threshold method, so as to calculate the ultrasonic forward and reverse flow propagation time and time difference in the synchronous acquisition mode, specifically including:

[0016] Taking the threshold method as an example, the calculation formula of ultrasound propagation time is as follows:

[0017] T f =T m -nT n

[0018] Among them, T f T is the ultrasonic propagation time, including the ultrasonic propagation time in the fluid downstream and the ultrasonic propagation time in the fluid upstream; m is the duration from the start of measurement to the time when the echo signal received by the transducer exceeds the preset threshold for the first time, n is the position difference between the target characteristic wave and the first wave, T n is the transducer cycle time;

[0019] Then, according to the obtained ultrasonic wave propagation time in the fluid downstream and the ultrasonic wave propagation time in the fluid upstream, the actual ultrasonic wave downstream and upstream propagation time difference is calculated as follows:

[0020] Δt=T fn -T fs

[0021] Among them, Δt is the difference in ultrasonic propagation time along and against the flow, T fn T is the propagation time of ultrasonic wave in the fluid. fs It is the propagation time of ultrasonic wave in the fluid downstream.

[0022] Furthermore, the flow velocity and flow rate of the fluid in the pipeline are calculated by using the time difference measurement principle of the clamp-on ultrasonic flowmeter and combining the measured pipeline cross-sectional parameters, including:

[0023] According to the ultrasonic wave propagation time in the fluid downstream, the ultrasonic wave propagation time in the fluid upstream and the ultrasonic wave propagation time difference in the fluid downstream and upstream, the fluid velocity and flow rate in the pipeline are calculated as follows:

[0024]

[0025]

[0026] Where v is the fluid velocity, Q is the fluid flow rate, k is the flow correction coefficient, A is the cross-sectional area of ​​the pipeline, is the ultrasonic incident angle, L is the ultrasonic propagation path length inside the fluid and is determined by the following formula:

[0027]

[0028] Among them, D i is the inner diameter of the pipe.

[0029] Compared with the prior art, the flow measurement method of the external clamp-on ultrasonic flowmeter using the synchronous acquisition mode provided by the present invention is different from the sequential data acquisition mode currently used in the external clamp-on ultrasonic flowmeter. By using the active synchronous acquisition mode, the two transducers are driven at the same time, and the receiving signals of the two transducers are recorded in the same time window. After processing the signals, the ultrasonic forward and reverse propagation time difference and the fluid flow rate in the pipe are calculated. Due to the linearity of the ultrasonic dynamic equation, the ultrasonic propagation behavior of the active synchronous acquisition mode is the same as that of the sequential data acquisition mode. However, the active synchronous acquisition mode enables the forward and reverse propagating ultrasound to pass through the fluid with the same temperature and flow profile, reducing the ultrasonic propagation speed and path fluctuations caused by temperature and flow field changes, thereby reducing the time difference measurement deviation and flow calculation error of the external clamp-on ultrasonic flowmeter, effectively reducing the flow calculation error, and improving the dynamic measurement performance of the flowmeter. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a flow chart of a flow measurement method of an external clamp-on ultrasonic flowmeter using a synchronous acquisition mode provided by the present invention.

[0031] Figure 2 The figure is a schematic diagram of the arrangement of the external clamp-on ultrasonic flowmeter transducer provided by the present invention on the pipe wall.

[0032] Figure 3 It is a schematic diagram of ultrasonic signal waveform and threshold method for calculating propagation time provided by the present invention.

[0033] Figure 4 It is a schematic diagram of the corresponding relationship between the speed of sound and temperature in the air involved in the present invention.

[0034] Figure 5 It is a schematic diagram of flow deviation of the external clamp-on ultrasonic flowmeter provided by the present invention in sequential acquisition mode and synchronous acquisition mode. DETAILED DESCRIPTION

[0035] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below with reference to specific diagrams.

[0036] In the description of the present invention, it should be understood that the terms "longitudinal", "radial", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0037] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] Please refer to Figure 1 As shown, the present invention provides a flow measurement method using an external clamp-on ultrasonic flowmeter in a synchronous acquisition mode, comprising:

[0039] The transducers of the two external clamp-on ultrasonic flowmeters arranged in sequence along the flow direction of the fluid in the pipeline are driven and transmitted simultaneously by the sinusoidal current signal from the function generator, and the received signals of the two transducers are recorded in the same time window, that is, the two transducers of the upstream and downstream are driven at the same time, so that the ultrasonic wave detected at each transducer passes through the same section of fluid at a constant temperature and flow profile during the measurement process;

[0040] Performing time domain analysis and frequency domain analysis on the ultrasonic signals synchronously collected by the upstream and downstream transducers. The specific methods of the time domain analysis and frequency domain analysis are prior arts well known to those skilled in the art and will not be described in detail here.

[0041] Using filters to filter the signals after time domain analysis and frequency domain analysis;

[0042] Amplify the filtered signal on two channels of the signal amplifier respectively;

[0043] Use a function generator to convert the amplified signal into a square wave output, and then use a multi-channel oscilloscope to digitize the square wave, and then output the captured signal, i.e., the digitized square wave, on different channels;

[0044] The acquisition process can be specifically controlled by Matlab or Python programming scripts. The script records one upstream waveform and one downstream waveform at the same time every second. The upstream and downstream transducers of the clamp-on ultrasonic flowmeter need to be equipped with a function generator, oscilloscope, filter and signal amplifier separately.

[0045] After obtaining the ultrasonic output signal, the digitized square wave is analyzed, and the ultrasonic propagation reference signal and echo signal characteristics are analyzed based on the cross-correlation method, curve fitting method or threshold method, so as to calculate the ultrasonic forward and reverse flow propagation time and time difference in the synchronous acquisition mode, and then the time difference measurement principle of the external clamp-on ultrasonic flowmeter is used, combined with the measurement of the pipeline cross-sectional parameters, to calculate the fluid velocity and flow rate in the pipeline.

[0046] As a specific embodiment, the sinusoidal current signal of the function generator is specifically a 12V sinusoidal current signal driven at a full-thickness resonant frequency of the piezoelectric element of 6MHz.

[0047] As a specific embodiment, the present invention uses a clamp-on ultrasonic flowmeter with a conventional sequential acquisition mode to test on a pipe with an outer diameter of 110 mm and a wall thickness of 5 mm. Air at 20°C and one atmospheric pressure flows through the pipe. The transducers of the upstream and downstream clamp-on ultrasonic flowmeters are arranged diagonally with a sound path, and the ultrasonic incident angle is 45° to the pipe axis. Specifically, Figure 2 As shown in the figure, the acoustic path refers to the distance that the sound wave travels in one direction between the upstream and downstream transducers.

[0048] As a specific embodiment, the digitized square wave is analyzed, and the ultrasonic propagation reference signal and echo signal characteristics are analyzed based on the cross-correlation method, the curve fitting method or the threshold method, so as to calculate the ultrasonic forward and reverse flow propagation time and time difference in the synchronous acquisition mode, specifically including:

[0049] Taking the threshold method as an example, Figure 3 As shown in Figure 2, the calculation formula for ultrasonic propagation time is as follows:

[0050] T f =T m -nT n Formula (1)

[0051] Among them, T f is the ultrasonic propagation time, including the ultrasonic propagation time in the fluid downstream and the ultrasonic propagation time in the fluid upstream. That is, both the ultrasonic downstream and upstream propagation time are calculated by formula (1); T m is the duration from the start of measurement to the time when the echo signal received by the transducer exceeds the preset threshold for the first time, n is the position difference between the target characteristic wave and the first wave, T n is the transducer cycle time;

[0052] Then, according to the obtained ultrasonic wave propagation time in the fluid downstream and the ultrasonic wave propagation time in the fluid upstream, the actual ultrasonic wave downstream and upstream propagation time difference is calculated as follows:

[0053] Δt=T fn -T fs Formula (2)

[0054] Among them, Δt is the difference in ultrasonic propagation time along and against the flow, T fn T is the propagation time of ultrasonic wave in the fluid. fs is the propagation time of ultrasonic wave in the fluid downstream;

[0055] In contrast, in the sequential acquisition mode of the traditional clamp-on ultrasonic flowmeter, the propagation time of the ultrasonic wave in the fluid in the downstream and upstream directions is calculated using the following formulas:

[0056]

[0057] Among them, t AB is the propagation time of ultrasonic wave in the fluid, t BA is the propagation time of ultrasonic wave in the fluid, c AB is the ultrasonic speed in downstream, c BA is the ultrasonic speed in counterflow, v is the fluid velocity, is the ultrasonic incident angle, L is the ultrasonic propagation path length inside the fluid and is determined by the following formula:

[0058]

[0059] Among them, D i is the inner diameter of the pipe.

[0060] In the sequential acquisition mode of the traditional clamp-on ultrasonic flowmeter, c AB and c BA They are considered equal, but in reality they may be different due to changes in temperature or flow field. The actual ultrasonic propagation time difference in the forward and reverse flow is calculated by equations (3) and (4) as follows:

[0061]

[0062] Among them, Δt sx is the ultrasonic propagation time difference between the upstream and downstream in the actual sequential acquisition mode of the clamp-on ultrasonic flowmeter. However, the instrument does not consider the error caused by the different ultrasonic sound velocities in the upstream and downstream when calculating. The ultrasonic sound velocity c of the upstream and downstream obtained by the synchronous acquisition mode proposed in this application is AB and c BAThis can directly compensate for the error caused by the difference between the two due to changes in temperature or flow field. Comparing the sequential acquisition mode (different ultrasonic sound velocities in the upstream and downstream) with the synchronous acquisition mode (equal ultrasonic sound velocities in the upstream and downstream), the difference in the time difference between the two is approximately:

[0063]

[0064] Among them, Δt s is the difference between the ultrasonic propagation time difference between the upstream and downstream with the change of sound velocity considered and the ultrasonic propagation time difference between the upstream and downstream without considering the change of sound velocity; c BA and c AB are the ultrasonic sound velocities in the forward and reverse flows without considering the change of sound velocity, and Δc is the difference in ultrasonic propagation velocity in the forward and reverse flows caused by the temperature change of sequential acquisition. Figure 4 This is a schematic diagram of the corresponding relationship between the speed of sound in the air and the temperature. It can be seen that for a 1°C change in air temperature, the change in the speed of sound is Δc = c BA -c AB , about 1m / s. Combining formula (7), we can calculate Δt s is 3.4 μs (per 1°C temperature change), which corresponds to about 0.33 m 3 / min flow measurement error.

[0065] At the same time, formula (7) expresses Δt s It is proportional to the length L of the ultrasonic propagation path in the fluid, which indicates that the time difference fluctuation caused by temperature fluctuation will increase linearly with the increase of the inner diameter of the pipe and the number of ultrasonic propagation paths. For example, in a larger pipe diameter or when a 2-path reflection arrangement is used, the time difference fluctuation will be greater than that in a small pipe diameter or when a 1-path diagonal arrangement is used.

[0066] As a specific embodiment, the flow velocity and flow rate of the fluid in the pipeline are calculated by using the time difference measurement principle of the external clamp-on ultrasonic flowmeter and combining the measured pipeline cross-sectional parameters, specifically including:

[0067] According to the ultrasonic wave propagation time in the fluid downstream, the ultrasonic wave propagation time in the fluid upstream and the ultrasonic wave downstream and upstream propagation time difference, the fluid velocity and flow rate in the pipeline are calculated by equation (1) and equation (2) respectively:

[0068]

[0069] Where v is the fluid velocity, Q is the fluid flow rate, k is the flow correction coefficient, A is the cross-sectional area of ​​the pipeline, is the ultrasonic incident angle, L is the length of the ultrasonic wave propagation path inside the fluid and is determined by the above formula (5).

[0070] On this basis, the deviation between the flow rate measured by the clamp-on ultrasonic flowmeter and the reference flow rate can be obtained as:

[0071]

[0072] Among them, Q dev is the flow measurement deviation, Q sur It is the standard flow rate obtained using a standard flow meter.

[0073] When using a traditional clamp-on ultrasonic flowmeter for measurement, the pipe outer diameter, wall thickness, material, measurement temperature, pressure, transducer spacing and other parameters are input into the host, and the measured flow velocity and flow rate can be directly read. The flow deviation can be obtained by comparing with the standard flow data. At the same time, the measurement data of the traditional clamp-on ultrasonic flowmeter will be synchronously stored in the internal storage card. Through the data processing software, detailed parameters such as the ultrasonic propagation waveform and the forward and reverse flow propagation time can be obtained.

[0074] Figure 5 The flow deviation of the conventional clamp-on ultrasonic flowmeter in the sequential acquisition mode and the synchronous acquisition mode of the present invention is shown. It can be found that under the pipeline conditions of this example, the sequential acquisition mode of two transducers is adopted, and the flow measurement deviation is in the range of 0.86% to 1.9% in the full flow range, while the synchronous acquisition mode of two transducers is adopted, and the flow measurement deviation is in the range of 0.65% to 1.37%. This shows that the acquisition mode of allowing two transducers to synchronously generate and receive ultrasonic waves can make the forward and reverse propagating ultrasound pass through the fluid with the same temperature and flow profile, and obtain a lower deviation than the sequential acquisition mode, thereby improving the measurement performance of the clamp-on ultrasonic flowmeter.

[0075] Compared with the prior art, the flow measurement method of the external clamp-on ultrasonic flowmeter using the synchronous acquisition mode provided by the present invention is different from the sequential data acquisition mode currently used in the external clamp-on ultrasonic flowmeter. By using the active synchronous acquisition mode, the two transducers are driven at the same time, and the receiving signals of the two transducers are recorded in the same time window. After processing the signals, the ultrasonic forward and reverse propagation time difference and the fluid flow rate in the pipe are calculated. Due to the linearity of the ultrasonic dynamic equation, the ultrasonic propagation behavior of the active synchronous acquisition mode is the same as that of the sequential data acquisition mode. However, the active synchronous acquisition mode enables the forward and reverse propagating ultrasound to pass through the fluid with the same temperature and flow profile, reducing the ultrasonic propagation speed and path fluctuations caused by temperature and flow field changes, thereby reducing the time difference measurement deviation and flow calculation error of the external clamp-on ultrasonic flowmeter, effectively reducing the flow calculation error, and improving the dynamic measurement performance of the flowmeter.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A flow measurement method using a clamp-on ultrasonic flowmeter in synchronous acquisition mode, characterized in that: include: The transducers of the two external clamp-on ultrasonic flow meters arranged in sequence along the flow direction of the fluid in the pipeline are driven and transmitted simultaneously by the sinusoidal current signal from the function generator, and the received signals of the two transducers are recorded in the same time window; Perform time domain analysis and frequency domain analysis on ultrasonic signals synchronously collected and received by the upstream and downstream transducers; Using filters to filter the signals after time domain analysis and frequency domain analysis; Amplify the filtered signal on two channels of the signal amplifier respectively; Use a function generator to convert the amplified signal into a square wave output, and then use a multi-channel oscilloscope to digitize the square wave, and then output the captured signal, i.e., the digitized square wave, on different channels; By analyzing the digitized square wave, the ultrasonic propagation reference signal and echo signal characteristics are analyzed based on the cross-correlation method, curve fitting method or threshold method, so as to calculate the ultrasonic forward and reverse flow propagation time and time difference in the synchronous acquisition mode, and then calculate the fluid velocity and flow in the pipeline through the time difference measurement principle of the external clamp-on ultrasonic flowmeter combined with the measurement of the pipeline cross-sectional parameters.

2. The flow measurement method using a clamp-on ultrasonic flowmeter in synchronous acquisition mode according to claim 1, characterized in that: The sinusoidal current signal of the function generator is specifically a 12V sinusoidal current signal driven at a full-thickness resonance frequency of the piezoelectric element of 6 MHz.

3. The flow measurement method using a clamp-on ultrasonic flowmeter in synchronous acquisition mode according to claim 1, characterized in that: The method analyzes the digitized square wave and analyzes the ultrasonic propagation reference signal and the echo signal characteristics based on the cross-correlation method, the curve fitting method or the threshold method, so as to calculate the ultrasonic forward and reverse flow propagation time and time difference in the synchronous acquisition mode, specifically including: Taking the threshold method as an example, the calculation formula of ultrasound propagation time is as follows: T f =T m nT n Among them, T f T is the ultrasonic propagation time, including the ultrasonic propagation time in the fluid downstream and the ultrasonic propagation time in the fluid upstream; m is the duration from the start of measurement to the time when the echo signal received by the transducer exceeds the preset threshold for the first time, n is the position difference between the target characteristic wave and the first wave, T n is the transducer cycle time; Then, based on the obtained ultrasonic wave propagation time in the fluid downstream and the ultrasonic wave propagation time in the fluid upstream, the actual ultrasonic wave downstream and upstream propagation time difference is calculated as follows: Δt=T fn -T fs Among them, Δt is the difference in ultrasonic propagation time along and against the flow, T fn T is the propagation time of ultrasonic wave in the fluid. fs It is the propagation time of ultrasonic wave in the fluid downstream.

4. The flow measurement method using a clamp-on ultrasonic flowmeter in synchronous acquisition mode according to claim 3, characterized in that: Then, the flow velocity and flow rate of the fluid in the pipeline are calculated by the time difference measurement principle of the clamp-on ultrasonic flowmeter and the measured pipeline cross-sectional parameters, including: According to the ultrasonic wave propagation time in the fluid downstream, the ultrasonic wave propagation time in the fluid upstream and the ultrasonic wave propagation time difference in the fluid downstream and upstream, the fluid velocity and flow rate in the pipeline are calculated as follows: Where v is the fluid velocity, Q is the fluid flow rate, k is the flow correction coefficient, A is the cross-sectional area of ​​the pipeline, is the ultrasonic incident angle, L is the ultrasonic propagation path length in the fluid and is determined by the following formula: Among them, D i is the inner diameter of the pipe.

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