Ultrasonic flow measurement method based on sound velocity tracking and flowmeter using the method

Abstract

The present invention discloses an ultrasonic flow measurement method based on sound velocity tracking and a flowmeter using the method. The method measures the downstream and upstream propagation time of an ultrasonic wave, calculates the sound velocity of the ultrasonic wave in the fluid to be measured, compares the sound velocity with the sound velocity in a calibration medium, and then calculates the flow velocity of the fluid in the pipe section in combination with the sum and difference of the downstream and upstream propagation time of the ultrasonic wave in the pipe section, thereby calculating the flow rate of the fluid. The method eliminates the influence of temperature on flow measurement without detecting the temperature of the fluid, thereby improving the measurement accuracy and stability of the flowmeter. The method only requires operation at a calibration temperature to complete the calibration step, and the material of the calibration medium and the actual medium to be measured can be different.

Description

Technical Field

[0001] The present invention relates to an ultrasonic flowmeter, and in particular to an ultrasonic flow measurement method based on sound velocity tracking used in the ultrasonic flowmeter and a flowmeter using the method. Background Art

[0002] Ultrasonic flowmeter is an instrument that measures flow by detecting the effect of fluid flow on ultrasonic beam (or ultrasonic pulse). Ultrasonic flowmeter has a variety of flow measurement principles such as time difference method, beam deviation method, Doppler method, etc. The time difference method is widely used in the field of ultrasonic flow measurement. Its principle is to calculate the flow velocity of the fluid by measuring the difference between the propagation time of ultrasonic signal in the fluid in the downstream and the propagation time in the upstream, and then calculate the flow rate of the fluid. Specifically, Figure 1 As shown, the flow meter 1 has a pipe section 2, and ultrasonic transducers 3a and 3b are respectively set upstream and downstream of the pipe section 2. The ultrasonic transducers 3a and 3b transmit and receive ultrasonic waves to each other, and the controller 4 measures the ultrasonic waves along the direction of fluid flow (see Figure 1 The propagation time of the ultrasonic wave propagating between the two ultrasonic transducers (in the direction of fluid inflow as shown by arrow A and in the direction of fluid outflow as shown by arrow B) and the propagation time of the ultrasonic wave propagating between the two ultrasonic transducers in the direction opposite to the fluid flow are calculated. When the ultrasonic wave propagates in the downstream direction, the propagation speed is accelerated by the fluid flow velocity, and when the ultrasonic wave propagates in the reverse direction, the propagation speed is slowed down by the fluid flow velocity. The flow velocity of the fluid can be calculated based on the difference between the measured upstream and downstream propagation times. The pipe section 2 of the ultrasonic flowmeter can be as follows: Figure 1 As shown in the broken line shape, the ultrasonic transducers 3a and 3b are respectively arranged at the upstream and downstream ends of the broken line segment of the pipe section. In this way, the ultrasonic transducer can be completely shielded by the pipe section to avoid contact between the fluid in the pipe section and the ultrasonic transducer, and to avoid mutual corrosion and contamination between the two; and the ultrasonic wave can be propagated in the medium basically in a straight path, which can reduce the energy loss caused by passing through the medium interface.

[0003] Temperature is a significant factor affecting the measurement accuracy of transit-time ultrasonic flowmeters. On the one hand, the speed of ultrasonic waves propagating in the medium (the velocity of sound) varies with temperature; on the other hand, the ultrasonic pipe section expands and contracts with temperature fluctuations, thus changing the propagation path of the ultrasonic waves. In conventional transit-time ultrasonic flowmeters, these two factors reduce the accuracy of flow measurement. A common solution is to install a temperature sensor (such as that disclosed in Chinese Invention Patent Publication No. CN103808381A) to measure the fluid temperature and then correct the measurement results based on the actual operating temperature. However, installing a temperature sensor inevitably increases the size, power consumption, and cost of the flowmeter, making it particularly difficult to install a temperature sensor for flowmeters requiring high measurement accuracy or a small installation space. Furthermore, relying on temperature detection to correct measurement errors requires calibration based on temperature during the calibration process. This requires calibrating the flowmeter at multiple temperatures, which is a labor-intensive process, especially for flowmeters with a wide operating temperature range or high measurement accuracy requirements. Summary of the Invention

[0004] The present invention aims to solve the problems in existing time-of-day ultrasonic flowmeters, such as the ultrasonic pipe section being easily affected by temperature changes, resulting in reduced flow measurement accuracy, and the addition of a temperature sensor easily increasing the volume, power consumption and cost of the flowmeter, and requiring a large calibration workload. The present invention provides an ultrasonic flow measurement method based on sound velocity tracking, which can solve the above technical problems and eliminate the influence of temperature on measurement accuracy, and a flowmeter using the method.

[0005] The specific technical solution adopted by the present invention to solve the above technical problems is: an ultrasonic flow measurement method based on sound velocity tracking, characterized in that it includes the following steps:

[0006] A1. Measure the downstream propagation time of ultrasonic waves between paired ultrasonic transducers and countercurrent propagation time ;

[0007] A2. Calculate the sum of the forward and reverse flow propagation time, recorded as the forward and reverse flow time and ; Calculate the difference in propagation time between upstream and downstream, recorded as upstream and downstream time difference ;

[0008] A3. According to the forward and reverse flow time Calculate the speed of ultrasound in the medium to be measured ;

[0009] A4. Calculate the sound velocity ratio, the sound velocity ratio is defined as the speed of sound of ultrasonic wave in the medium to be measured. and the speed of sound in the calibration medium The ratio of

[0010] A5. Flow rate calculation formula determined based on calibration conditions Calculate the flow velocity, which includes the sound velocity ratio Time difference between upstream and downstream Calculation formula:

[0011] A6.Calculate the flow rate of the medium to be measured based on the flow velocity.

[0012] There is no need to add a temperature sensor. The propagation time of the ultrasonic wave in the fluid to be measured is used to calculate the sound velocity of the ultrasonic wave. This is compared with the sound velocity in the calibration medium. The flow velocity of the fluid in the pipe section is calculated based on the difference in the propagation time of the ultrasonic wave in the pipe section. The flow rate of the fluid is then calculated. This can eliminate the influence of temperature on the measurement accuracy and improve the flow measurement accuracy.

[0013] Preferably, the calibration step of determining the flow rate calculation formula includes the following steps:

[0014] B1. Supply a fluid flow of preset flow rate and preset temperature to the ultrasonic flowmeter to be calibrated. The preset flow rate is recorded as the calibration flow rate. , the preset temperature is recorded as the calibration temperature ;

[0015] B2. Read the ultrasonic flowmeter's output of the measured forward and reverse flow time difference ;

[0016] B3. Change the flow rate Repeat steps B1-B2 to obtain different flow rates Multiple markers under the time difference of upstream and downstream data;

[0017] B4. Flow rate measurement and measuring the time difference between forward and reverse flow Perform data fitting to obtain the calibration flow rate calculation formula , and then determine the flow rate calculation formula for measuring the medium to be measured .

[0018] Preferably, the flow rate calculation formula has form, in which is the distance that the ultrasonic wave propagates in the fluid in the pipe section. 、 and is a constant.

[0019] Preferably, the A3-A4 steps in the above scheme are replaced by the following AA4 steps:

[0020] AA4. Calculate the sound velocity ratio, sound velocity ratio The calculation formula is ; Other steps remain unchanged.

[0021] Preferably, the steps A3-A4 in the above scheme are replaced by the following steps AB4:

[0022] AB4. Calculate the sound speed ratio, where the sound speed ratio The calculation formula is ; Other steps remain unchanged.

[0023] Another object of the present invention is to provide an ultrasonic flow measurement method based on sound velocity tracking, which is characterized by comprising the following steps:

[0024] C1. Measure the downstream propagation time of ultrasonic waves between paired ultrasonic transducers and countercurrent propagation time ;

[0025] C2. Calculate the sum of the upstream and downstream propagation times, recorded as the upstream and downstream time ; Calculate the difference in propagation time between upstream and downstream, recorded as upstream and downstream time difference ;

[0026] C3. According to the forward and reverse flow time Calculate the speed of ultrasound in the medium to be measured ;

[0027] C4. Calculate the sound velocity ratio, the sound velocity ratio is defined as the speed of sound of ultrasonic wave in the medium to be measured. and the speed of sound in the calibration medium The ratio of

[0028] C5. Flow rate calculation formula determined based on calibration conditions Calculate the flow velocity, which includes the sound velocity ratio , downstream and upstream time and the time difference between upstream and downstream Calculation formula:

[0029] C6. Calculate the flow rate of the medium to be measured based on the flow velocity.

[0030] As an advantage, the flow rate calculation formula has form, in which 、 and is a constant.

[0031] Another invention object of the present application is to provide an ultrasonic flowmeter, characterized in that it includes a pipe section, an ultrasonic transducer, and a controller; the pipe section is arranged in a three-section broken line shape, the middle section of the pipe section is straight, and a pair of ultrasonic transducers are respectively attached to the wall surfaces at both ends of the middle section of the pipe section in the axial direction, for transmitting and receiving ultrasonic waves to each other; the controller includes a driving module, a computing module, and a storage module; the driving module is connected to the ultrasonic transducer and is used to excite and control the ultrasonic transducer and transmit and receive ultrasonic signals; the computing module is connected to the driving module and is used to measure the downstream propagation time and upstream propagation time of the ultrasonic wave propagating between the paired ultrasonic transducers; the computing module is connected to the storage module, and the storage module is used to store the software program of the flowmeter;

[0032] The software program stored in the storage module includes a flow rate calculation formula determined during the flow meter calibration process, and the software program includes processing steps determined according to the ultrasonic flow measurement method described in one of the above technical solutions; the operation module reads the software program from the storage module, and calculates the flow rate of the fluid passing through the ultrasonic flow meter based on the flow rate calculation formula using the downstream propagation time and upstream propagation time obtained by actual measurement.

[0033] The beneficial effects of the present invention are as follows: the present invention relates to a flow measurement method and a flowmeter using the method, which measures the downstream and upstream propagation time of an ultrasonic wave, calculates the sound velocity of the ultrasonic wave in the fluid to be measured, compares the sound velocity with the sound velocity in the calibration medium, and then calculates the flow velocity of the fluid in the pipe section based on the difference in the downstream and upstream propagation time of the ultrasonic wave in the pipe section, thereby calculating the flow rate of the fluid; and has the following advantages:

[0034] (1) The influence of temperature on flow measurement can be eliminated without detecting the temperature of the fluid, which improves the measurement accuracy and stability of the flow meter. It does not require the installation of a temperature sensor, and is particularly suitable for small-volume ultrasonic flow meters.

[0035] (2) The calibration steps can be completed by operating at a calibration temperature, and the calibration medium can be different from the material of the actual medium to be measured; the steps of the flow meter calibration process are significantly reduced, and it is beneficial to improve the flow measurement accuracy of the flow meter at different temperatures or when measuring different media; it is particularly suitable for use in the field of chemical transportation pipelines.

[0036] (3) According to one aspect of the present invention, flow measurement can be achieved without measuring the length of the pipe section of the ultrasonic flowmeter, thereby avoiding errors in length measurement and errors in flow measurement caused by the thermal expansion and contraction effects of the pipe section;

[0037] (4) According to one aspect of the present invention, the influence of the flow meter wall thickness and / or the influence of the difference between the timing point of the ultrasonic wave and the actual arrival time are corrected in the process of obtaining the sound velocity of the medium to be measured, thereby improving the measurement accuracy of the flow meter. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] Figure 1 This is a schematic diagram of the principle structure of a time-difference ultrasonic flowmeter.

[0040] Figure 2 It is a waveform diagram of ultrasonic signal.

[0041] Figure 3 It is a schematic diagram of the principle of the ultrasonic flowmeter applied in the present invention. DETAILED DESCRIPTION

[0042] like Figure 1 As shown, the pipe section 2 of the ultrasonic flowmeter 1 is set in a three-section broken line shape, and the middle section of the pipe section 2 is straight. The ultrasonic transducers 3a and 3b are respectively attached to the wall surfaces at both ends of the middle section in the axial direction of the pipe section; the ultrasonic transducers 3a and 3b do not contact the fluid in the pipe section, and the ultrasonic transducers will not be corroded by the fluid, nor will they contaminate the fluid. It is particularly suitable for pipeline systems with high cleanliness requirements such as electronic chemicals. The transmission of ultrasonic waves through the pipe section wall will cause energy loss. Figure 1 In the device, the ultrasonic transducers are set at both ends of the straight pipe section in the axial direction, so that the ultrasonic wave propagates basically in a straight line between the two transducers, reducing the energy loss caused by reflection and refraction when passing through the wall of the pipe section, which is beneficial to improving the signal quality of the ultrasonic wave and is particularly suitable for the measurement of small flow rates.

[0043] The inner length of the straight pipe section with ultrasonic transducers installed at both ends is L, which is also the distance (sound path) that the ultrasonic wave propagates in the fluid medium. The downstream propagation time of the ultrasonic wave from the ultrasonic transducer 3a to 3b is for:

[0044]

[0045] in, For the sound range, is the speed of sound, is the fluid flow rate.

[0046] The backflow propagation time of the ultrasonic wave from the ultrasonic transducer 3b to 3a for:

[0047]

[0048] Example 1:

[0049] Combining (1) and (2) we can get the calculation formula:

[0050]

[0051]

[0052] in, is the time difference between upstream and downstream, that is, the downstream propagation time and countercurrent propagation time difference; is the upstream and downstream time, that is, the downstream propagation time and countercurrent propagation time The harmony.

[0053] The speed of sound in a fluid is generally significantly greater than the flow velocity of the fluid. For example, the propagation speed of ultrasound in water is approximately 1400 m / s, while the typical flow velocity of the fluid in an ultrasonic flowmeter is around 5 m / s. When the speed of sound is much greater than the flow velocity of the fluid, the above equations (3) and (4) can be rewritten as:

[0054]

[0055]

[0056] If the sound velocity in the calibration medium of the flow meter is known ; The time difference between forward and reverse flow measured by the flowmeter during the calibration process is , measure the forward and reverse flow time and ; The speed of sound in the medium to be measured is The time difference between forward and reverse flow is , downstream and upstream time and ; In addition, define another coefficient, the speed of sound ratio Then, according to (5) and (6), we can get:

[0057]

[0058]

[0059] According to equations (7) and (8), the forward and reverse flow time measured by the flowmeter in the medium to be measured can be and the time difference between upstream and downstream Converted into the measured forward and reverse flow time and time measured by the flow meter in the calibration medium and measuring the time difference between forward and reverse flow .

[0060] During the calibration process, the speed of sound in the calibration medium can be determined , and the flow rate of the calibration medium and measuring the time of upstream and downstream and measuring the time difference between forward and reverse flow The relationship between them; the sound velocity in the medium to be measured can be calculated using the following formula:

[0061]

[0062] Therefore, with the help of the sound speed ratio The flow rate of the medium to be measured can be calculated by conversion.

[0063] The specific steps of the flow measurement method of this embodiment are:

[0064] A1. Measure the downstream propagation time of ultrasonic waves between paired ultrasonic transducers and countercurrent propagation time ;

[0065] A2. Calculate the sum of the forward and reverse flow propagation time, recorded as the forward and reverse flow time and ; Calculate the difference in propagation time between upstream and downstream, recorded as upstream and downstream time difference ;

[0066] A3. According to the forward and reverse flow time Calculate the speed of ultrasound in the medium to be measured ;

[0067] A4. Calculate the sound velocity ratio, the sound velocity ratio is defined as the speed of sound of ultrasonic wave in the medium to be measured. and the speed of sound in the calibration medium The ratio of

[0068] A5. Flow rate calculation formula determined based on calibration conditions Calculate the flow velocity, which includes the sound velocity ratio Time difference between upstream and downstream Calculation formula:

[0069] A6.Calculate the flow rate of the medium to be measured based on the flow velocity.

[0070] In this embodiment, the flow rate calculation formula is as follows:

[0071]

[0072] in, The speed of the ultrasonic wave in the calibration medium has a certain temperature. It can be directly measured through the calibration process or obtained by consulting known technical literature; It is the distance that the ultrasonic wave propagates in the fluid in the pipe section, which is obtained by measuring the flow meter structure; 、 and are fitting coefficients, which are determined through the calibration step.

[0073] The fitting coefficients are specifically determined through the following calibration steps 、 and :

[0074] B1. Supply a fluid flow of preset flow rate and preset temperature to the ultrasonic flowmeter to be calibrated. The preset flow rate is recorded as the calibration flow rate. , the preset temperature is recorded as the calibration temperature ;

[0075] B2. Read the ultrasonic flowmeter's output of the measured forward and reverse flow time difference ;

[0076] B3. Change the flow rate Repeat steps B1-B2 to obtain different flow rates Multiple markers under the time difference of upstream and downstream data;

[0077] B4. Flow rate measurement and measuring the time difference between forward and reverse flow Perform data fitting to obtain the calibration flow rate calculation formula , and then the fitting coefficient can be determined 、 and , and the ultrasonic flowmeter is used to measure the flow rate of the medium to be measured .

[0078] For the case where the calibration sound velocity is determined by the calibration step, the calibration forward and reverse flow times can be measured in the calibration step. Data, combined with the measured sound path Data, using formula (9) to calculate the measured sound velocity .

[0079] In this embodiment, only one calibration temperature is required. The calibration process is completed with the following steps, and the calibration medium can be made of a different material than the actual medium being measured. Based on the difference in sound velocity between the actual medium being measured and the calibration medium, the calibration flow velocity formula can be modified and used to measure the flow velocity of the measured medium. This method significantly reduces the number of steps in the flowmeter calibration process and helps improve the flow measurement accuracy of the flowmeter at different temperatures or when measuring different media. Because this measurement method relies on comparing the sound velocity difference between the measured medium and the calibration medium, it can be called the sound velocity tracking method.

[0080] This measurement method is particularly well-suited for use in chemical pipelines. Some chemical pipelines carry multiple fluids, while others carry only a single type of fluid, yet the entire system includes multiple pipelines transporting different chemicals. Using the flow measurement method of this embodiment, calibration only requires one fluid type to accommodate measurement of multiple fluids, expanding the flowmeter's applicability and reducing the number of flow measurement steps and the number of flowmeter models required.

[0081] Example 2:

[0082] Combining the above two equations (3) and (4), we can get:

[0083]

[0084] For the calibration process, the calibration flow rate calculation formula can be obtained:

[0085]

[0086] Combining equations (7) and (8) we can obtain the flow rate calculation formula for the fluid to be measured:

[0087]

[0088] Preferably, the following formula is used as the flow rate calculation formula:

[0089] in, is the fitting coefficient, which can be determined through the flow meter calibration procedure.

[0090] The specific steps of the flow measurement method of this embodiment are:

[0091] C1. Measure the downstream propagation time of ultrasonic waves between paired ultrasonic transducers and countercurrent propagation time ;

[0092] C2. Calculate the sum of the upstream and downstream propagation times, recorded as the upstream and downstream time ; Calculate the difference in propagation time between upstream and downstream, recorded as upstream and downstream time difference ;

[0093] C3. According to the forward and reverse flow time Calculate the speed of ultrasound in the medium to be measured ;

[0094] C4. Calculate the sound velocity ratio, the sound velocity ratio is defined as the speed of sound of ultrasonic wave in the medium to be measured. and the speed of sound in the calibration medium The ratio of

[0095] C5. Flow rate calculation formula determined based on calibration conditions Calculate the flow velocity, which includes the sound velocity ratio , downstream and upstream time and the time difference between upstream and downstream Calculation formula:

[0096] C6. Calculate the flow rate of the medium to be measured based on the flow velocity.

[0097] In this embodiment, the flow rate calculation formula is:

[0098]

[0099] The fitting coefficients are specifically determined through the following calibration steps 、 and :

[0100] D1. Supply a fluid flow of preset flow rate and preset temperature to the ultrasonic flowmeter to be calibrated. The preset flow rate is recorded as the calibration flow rate. , the preset temperature is recorded as the calibration temperature ;

[0101] D2. Read the ultrasonic flowmeter's output of measured forward and reverse flow time and and measuring the time difference between forward and reverse flow ;

[0102] D3. Change the flow rate Repeat steps D1-D2 to obtain different flow rates Multiple sets of mapping of forward and reverse flow time and and measuring the time difference between forward and reverse flow data;

[0103] D5. Measure flow rate against standard , measure the forward and reverse flow time and and measuring the time difference between forward and reverse flow Perform data fitting to obtain the calibration flow rate calculation formula , and then the fitting coefficient can be determined 、 and , and the ultrasonic flowmeter is used to measure the flow rate of the medium to be measured .

[0104] Compared with Example 1, the calculation formula of this embodiment no longer includes the sound path Therefore, compared with Example 1, this embodiment no longer relies on the sound path Moreover, the flow rate calculation formula of Example 1 takes the sound path as Treated as a constant and cannot adapt to the sound path This embodiment solves the problem of temperature change.

[0105] Therefore, Example 2 is more suitable for ultrasonic flowmeters with obvious thermal expansion and contraction effects of pipe materials. For example, plastic materials such as polytetrafluoroethylene are often used as pipe materials for ultrasonic flowmeters in chemical pipeline systems to avoid corrosion and pollution problems. The technical solution of this embodiment can greatly improve the measurement accuracy of such ultrasonic flowmeters.

[0106] Example 3:

[0107] In Example 1, the acoustic path can be used according to formula (9) and upstream and downstream time To calculate the sound velocity of the medium to be measured However, the acoustic path refers only to the distance the ultrasonic wave travels in the fluid medium and does not include the distance the ultrasonic wave travels within the pipe wall between the ultrasonic transducer and the fluid medium. Because the speed of sound in solid media is often higher than that in fluid media, and pipe wall thickness is not very large, the pipe wall thickness has little effect on flow measurement accuracy in the general application of the present invention.

[0108] If you want to obtain higher measurement accuracy, you can consider correcting the effect of the flowmeter wall thickness. Since the speed of ultrasound in the pipe wall is high and the pipe wall thickness is relatively small, it can be approximately assumed that the transmission time consumed by ultrasound in the calibration condition and the actual measurement condition is equal, which can be recorded as Therefore, under the calibration conditions, the transmission time can be calculated using the following formula: :

[0109]

[0110] Therefore, the sound velocity in the medium to be measured is The calculation formula is modified to:

[0111]

[0112] The calculation formula of the sound speed ratio is corrected to:

[0113]

[0114] In this embodiment, steps A3-A4 in Example 1 are replaced by the following step AA4:

[0115] AA4. Calculate the sound velocity ratio, sound velocity ratio The calculation formula is ;

[0116] The rest of the implementation is the same as Example 1.

[0117] Example 4:

[0118] like Figure 2 As shown, the threshold method is often used in ultrasonic flow meters to measure the propagation time of ultrasonic waves. The sound wave waveform excited each time by the ultrasonic transducer is a series of waves with a spindle-shaped envelope. It is very important to accurately obtain the moment when the ultrasonic wave arrives at the receiving ultrasonic transducer, that is, to obtain the starting point of the ultrasonic waveform received by the receiving ultrasonic transducer for measurement accuracy. In order to avoid interference from noise signals and accurately confirm the receipt of ultrasonic signals, the threshold method can be used to determine the starting point of the waveform. The ultrasonic signal has a series of zero-crossing points such as 101-104 that cross the zero axis from negative to positive. When the peak value of the waveform signal is detected to exceed the threshold line 110, the first zero-crossing point 104 after the peak 111 is taken as the timing point. However, the actual moment when the ultrasonic wave arrives at the receiving transducer should be the zero-crossing point 101. The timing point obtained in the flow measurement method is 3 sound wave cycles later than the actual timing point. .

[0119] Refer to formula (18), in order to further improve the sound velocity in the medium to be measured Sonic speed ratio The measurement accuracy is calculated by the following formula: :

[0120]

[0121] in, It is the order of the preset timing points in the zero crossing of the ultrasonic waveform, and is the ultrasonic wave period. ; and All can be determined according to the design parameters of the flow meter.

[0122] In this embodiment, steps A3-A4 in Example 1 are replaced by the following steps AB4:

[0123] AB4. Calculate the sound velocity ratio, sound velocity ratio The calculation formula is

[0124] ;

[0125] The rest of the implementation is the same as Example 1.

[0126] Ultrasonic flow meter example:

[0127] like Figure 3 As shown, the pipe section 2 of the ultrasonic flowmeter 1 is set in a three-section broken line shape, the middle section of the pipe section 2 is a straight line, and the ultrasonic transducers 3a and 3b are respectively attached to the wall surfaces at both ends of the middle section of the pipe section in the axial direction; the ultrasonic waves 3a and 3b can transmit and receive ultrasonic waves to each other; the ultrasonic waves are transmitted along the direction of the fluid flow (see Figure 3 The ultrasonic flowmeter 1 also includes a controller 4, which includes a driving module 5, an operation module 6 and a storage module 7; the driving module 5 is connected to the ultrasonic transducers 3a and 3b, and is used to excite and control the ultrasonic transducers 3a and 3b to transmit and receive ultrasonic signals, and the operation module 6 is connected to the driving module 5, and is used to measure the downstream propagation time and the upstream propagation time of the ultrasonic wave propagating between the ultrasonic transducers 3a; the operation module 6 is also connected to the storage module 7, and the storage module 7 is used to store the software program of the flowmeter, the software program includes a flow rate calculation formula determined during the flowmeter calibration process, and the software program includes processing steps determined according to the ultrasonic flow measurement method provided in this application; the operation module 6 reads the software program from the storage module 7, and calculates the flow rate of the fluid passing through the ultrasonic flowmeter according to the flow rate calculation formula using the downstream propagation time and the upstream propagation time obtained by actual measurement.

[0128] The above content and structure describe the basic principles, main features, and advantages of the product of the present invention, which should be understood by those skilled in the art. The above examples and description are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications are intended to be within the scope of the invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. An ultrasonic flow measurement method based on sound velocity tracking, characterized by: Includes the following steps A1. Measure the downstream propagation time of ultrasonic waves between paired ultrasonic transducers and countercurrent propagation time ; A2. Calculate the sum of the forward and reverse flow propagation time, recorded as the forward and reverse flow time and ; Calculate the difference in propagation time between upstream and downstream, and record it as upstream and downstream time difference ; A3. According to the forward and reverse flow time Calculate the speed of ultrasound in the medium to be measured ; A4. Calculate the sound velocity ratio, the sound velocity ratio is defined as the speed of sound of ultrasonic wave in the medium to be measured. and the speed of sound in the calibration medium The ratio of A5. Flow rate calculation formula determined based on calibration conditions Calculate the flow velocity, which includes the sound velocity ratio Time difference between upstream and downstream Calculation formula: A6. Calculate the flow rate of the medium to be measured based on the flow velocity; The calibration step of determining the flow rate calculation formula includes the following steps: B1. Supply a fluid flow of preset flow rate and preset temperature to the ultrasonic flowmeter to be calibrated. The preset flow rate is recorded as the calibration flow rate. , the preset temperature is recorded as the calibration temperature ; B2. Read the ultrasonic flowmeter's output of the measured forward and reverse flow time difference ; B3. Change the flow rate Repeat steps B1-B2 to obtain different flow rates Multiple markers under the time difference of upstream and downstream data; B4. Flow rate measurement and measuring the time difference between forward and reverse flow Perform data fitting to obtain the calibration flow velocity calculation formula , and then determine the flow rate calculation formula for measuring the medium to be measured ; The flow rate calculation formula has form, in which is the distance that the ultrasonic wave propagates in the fluid in the pipe section. 、 and is a constant.

2. The ultrasonic flow measurement method based on sound velocity tracking according to claim 1, characterized in that: Replace steps A3-A4 in claim 1 with the following step AA4: AA4. Calculate the sound velocity ratio, sound velocity ratio The calculation formula is ; Other steps remain unchanged, among which is the distance that the ultrasonic wave propagates in the fluid in the pipe section. is the speed of sound in the calibration medium, It is the time of upstream and downstream, It is used to measure the forward and reverse flow time.

3. The ultrasonic flow measurement method based on sound velocity tracking according to claim 1, characterized in that: The steps A3-A4 in claim 1 are replaced with the following steps AB4: AB4. Calculate the sound speed ratio, where the sound speed ratio The calculation formula is ,in, is the distance that the ultrasonic wave propagates in the fluid in the pipe section. is the speed of sound in the calibration medium, It is the time of upstream and downstream, It is used to measure the forward and reverse flow time. is the sound wave period, It is the order of the preset timing points in the zero crossing point of the ultrasonic waveform; other steps remain unchanged.

4. An ultrasonic flow measurement method based on sound velocity tracking, characterized in that: The following steps are involved: C1. Measure the downstream propagation time of ultrasonic waves between paired ultrasonic transducers and countercurrent propagation time ; C2. Calculate the sum of the upstream and downstream propagation times, recorded as the upstream and downstream time ; Calculate the difference in propagation time between upstream and downstream, and record it as upstream and downstream time difference ; C3. According to the forward and reverse flow time Calculate the speed of ultrasound in the medium to be measured ; C4. Calculate the sound velocity ratio, the sound velocity ratio is defined as the speed of sound of ultrasonic wave in the medium to be measured. and the speed of sound in the calibration medium The ratio of C5. Flow rate calculation formula determined based on calibration conditions Calculate the flow velocity, which includes the sound velocity ratio , downstream and upstream time and the time difference between upstream and downstream Calculation formula: C6. Calculate the flow rate of the medium to be measured based on the flow velocity; The flow rate calculation formula has form, in which 、 and is a constant.

5. An ultrasonic flow meter, characterized in that: The flowmeter comprises a pipe section, an ultrasonic transducer, and a controller; the pipe section is arranged in a three-section broken line shape, with the middle section of the pipe section being a straight line; a pair of ultrasonic transducers are respectively attached to the wall surfaces at both ends of the middle section in the axial direction of the pipe section, for mutually transmitting and receiving ultrasonic waves; the controller comprises a drive module, a calculation module, and a storage module; the drive module is connected to the ultrasonic transducer and is used to excite and control the ultrasonic transducer and transmit and receive ultrasonic signals; the calculation module is connected to the drive module and is used to measure the downstream propagation time and upstream propagation time of the ultrasonic wave propagating between the paired ultrasonic transducers; the calculation module is connected to the storage module, and the storage module is used to store the software program of the flowmeter; The software program stored in the storage module includes a flow rate calculation formula determined during the flow meter calibration process, and the software program includes processing steps determined by the ultrasonic flow measurement method according to one of claims 1 to 4; the operation module reads the software program from the storage module, and calculates the flow rate of the fluid passing through the ultrasonic flow meter according to the flow rate calculation formula using the downstream propagation time and upstream propagation time obtained by actual measurement.

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