阅读说明：本技术 一种多声道同步发射流速测量装置及方法 (Multi-channel synchronous emission flow velocity measuring device and method ) 是由 方立德 苑欣悦 周琮 韦子辉 于 2021-08-30 设计创作，主要内容包括：本发明提供了一种多声道同步发射流速测量装置及方法。本发明使N个超声波换能器均布在管道侧壁的同一横截面上,另外N个超声波换能器均布在管道侧壁的另一横截面上,前N个超声波换能器对应在后N个超声波换能器中,总能找到与之连线与轴心线相交的超声波换能器,将这样的两个超声波换能器称为一对超声波换能器；由两对超声波换能器可求解出一个流速。对所有流速求平均可得流速均值。本发明运用计时芯片和微控制器的特性设计集成芯片,实现超声波流量计数据的远传的远程抄表功能,利用相关运算得到流体的速度,为超声流速的测量提供了一种新的思路。本发明还集成了窄带物联网技术,相应数据可以上传至上位机,提高了超声波流量计的智能化水平。(The invention provides a multi-channel synchronous emission flow velocity measuring device and a method. The invention makes N ultrasonic transducers evenly distributed on the same cross section of the side wall of the pipeline, in addition, N ultrasonic transducers evenly distributed on the other cross section of the side wall of the pipeline, the front N ultrasonic transducers correspond to the rear N ultrasonic transducers, the ultrasonic transducers with the connecting line intersected with the axial lead can be always found, and the two ultrasonic transducers are called as a pair of ultrasonic transducers; one flow rate can be solved by two pairs of ultrasonic transducers. The average flow rate is averaged over all flow rates. The invention designs the integrated chip by using the characteristics of the timing chip and the microcontroller, realizes the remote meter reading function of the remote transmission of the data of the ultrasonic flowmeter, obtains the speed of the fluid by using related operations, and provides a new idea for the measurement of the ultrasonic flow rate. The invention also integrates the technology of narrow-band Internet of things, corresponding data can be uploaded to an upper computer, and the intelligent level of the ultrasonic flowmeter is improved.)

1. A multi-channel synchronous emission flow velocity measuring device is characterized by comprising 2N ultrasonic transducers, wherein N is more than or equal to 3; the N ultrasonic transducers are uniformly distributed on the same cross section of the side wall of the pipeline and are called as a first group of ultrasonic transducers; the other N ultrasonic transducers and the first group of ultrasonic transducers are uniformly distributed on the other cross section of the side wall of the pipeline in the same arrangement mode, and the N ultrasonic transducers are called as a second group of ultrasonic transducers; the N ultrasonic transducers in the first group and the N ultrasonic transducers in the second group are in one-to-one correspondence on the same bus; each ultrasonic transducer in the first group corresponds to the ultrasonic transducer in the second group, and the ultrasonic transducer which is connected with the ultrasonic transducer and intersected with the axial lead can be always found, and the two ultrasonic transducers are called as a pair of ultrasonic transducers; two pairs of ultrasonic transducers can solve a flow velocity, N pairs of ultrasonic transducers can at least solve N/2 and get an integer of flow velocity downwards, and at most can solve N flow velocities; the average flow rate is averaged over all flow rates.

2. The multi-channel synchronous emission flow velocity measurement device according to claim 1, wherein in solving for a flow velocity by two pairs of ultrasonic transducers, one pair of ultrasonic transducers is used to measure the downstream propagation time of the ultrasonic wave in the fluid, and the other pair of ultrasonic transducers is used to measure the upstream propagation time of the ultrasonic wave in the fluid.

3. The multi-channel synchronous emission flow velocity measuring device as claimed in claim 1, wherein an ultrasonic probe is provided at a front end of each ultrasonic transducer, and each ultrasonic transducer is a transceiver-integrated ultrasonic transducer.

4. The multi-channel simultaneous emission flow velocity measuring apparatus according to claim 3, wherein the N ultrasonic transducers on the same cross-section are fixed by an attachment means, the attachment means is similar to a strap structure, and the attachment means is provided with screw threads at equal intervals, and the corresponding ultrasonic probe is fixed by the screw threads.

5. The multi-channel synchronous emission flow velocity measuring device as recited in claim 1, further comprising a channel control module and a timing module connected to each ultrasonic transducer, wherein the channel control module and the timing module are further connected to the single chip microcomputer respectively; the single chip microcomputer is connected with an upper computer through a USB communication module.

6. The multi-channel synchronous emission flow velocity measurement device as claimed in claim 5, wherein the channel control module employs a 74HC4052D chip, the timing module employs a TDC-GP22 chip, and the single chip microcomputer employs an MSP430FR6047 chip.

7. A multichannel synchronous emission flow velocity measuring method is characterized by comprising the following steps:

a. arranging 2N ultrasonic transducers according to claim 1 on the side wall of the pipeline;

b. under the control of the single chip microcomputer, the channel control module controls the ultrasonic transducers to work simultaneously, wherein one ultrasonic transducer in each pair of ultrasonic transducers is used for transmitting an ultrasonic signal, and the other ultrasonic transducer in each pair of ultrasonic transducers is used for receiving the ultrasonic signal;

c. the channel control module and the timing module collect ultrasonic signals transmitted/received by the ultrasonic probes at the front ends of the ultrasonic transducers and send the collected signals to the single chip microcomputer;

d. the single chip microcomputer stores and processes the received data and sends the corresponding data to an upper computer;

e. the upper computer calculates the flow rate according to the following formula:

in the above formula, T₁Is the downstream propagation time, T, of the ultrasonic signal in the fluid₂The counter-current propagation time of the ultrasonic signals in the fluid is shown, L is the distance between two ultrasonic transducers on the same bus, and theta is the included angle between the connecting line of each pair of ultrasonic transducers and the pipe wall;

one flow velocity v can be solved by two pairs of ultrasonic transducers, and the average value of the flow velocity is solved by solving a plurality of flow velocities.

8. The multi-channel synchronous emission flow velocity measurement method as claimed in claim 7, wherein the channel control module employs a 74HC4052D chip, the timing module employs a TDC-GP22 chip, and the single chip microcomputer employs an MSP430FR6047 chip.

Technical Field

The invention relates to the technical field of two-phase flow detection, in particular to a multi-channel synchronous emission flow velocity measuring device and method.

Background

At present, the ultrasonic velocity measurement method is sometimes a difference method, a Doppler velocity measurement method, a frequency difference method and the like.

The time difference method measures the time difference of ultrasonic waves emitted in two different directions along the flow of a fluid to reach a receiving end. The time difference method is a measuring principle method which is applied to a gas ultrasonic flowmeter at present. The gas ultrasonic flowmeter mainly comprises an ultrasonic transducer group, a signal processing circuit and an integrating system. The ultrasonic transmitting transducer transmits ultrasonic beams to penetrate through the fluid to be detected, the ultrasonic receiving transducer converts received signals into electric signals after amplification and filtering processing, the electric signals are accumulated by an integrating system, and finally the flow speed detection is realized.

The doppler ultrasonic velocimetry is a method of measuring the doppler shift of a sound wave scattered by moving particles in a fluid by using the doppler effect of the sound wave propagating in the fluid, and thus the velocity of the fluid can be obtained. The method is suitable for flow rate measurement of open channels, riverways and difficult-to-construct standard sections and flow rate measurement of various full-pipe and non-full-pipe open channels.

The frequency difference method can avoid the influence of the sound velocity changing along with the temperature, but the frequency measurement has a positive and negative one error, and a high-speed counter is needed for a place with high precision.

Currently, Yamanaka proposes a novel ultrasonic time-domain cross-correlation (UTDC) method for measuring a fluid velocity field. Compared with the traditional ultrasonic flowmeter, the method has the advantages that the flow velocity of the fluid is measured by two continuous corresponding ultrasonic pulses, the time and space resolution is improved, and the problem of limitation of the maximum measurable flow velocity due to the Nyquist's sampling theorem is solved.

At present, in the process of detecting the flow velocity of gas-liquid two-phase flow liquid, domestic and foreign ultrasonic flow meters cannot simultaneously measure the flow velocity of fluid flowing through at the same time point, so that the actual measurement precision often cannot reach the set precision. Moreover, the problems of flow cutoff and production stoppage and the like can be involved in the installation and the disassembly of the conventional ultrasonic flowmeter, the influence of the flow velocity of liquid in a pipeline on the propagation velocity of ultrasonic guided waves is researched, the flow detection is realized in the non-flowing state of the pipeline, particularly the problems of flow cutoff and production stoppage and the like can be avoided for the measurement of the liquid flow in the pipeline with small diameter, the economic loss caused by the conventional detection method is reduced, a new method is provided for flow measurement, and the wide attention at home and abroad is attracted.

Disclosure of Invention

The invention aims to provide a multi-channel synchronous emission flow velocity measuring device and a method thereof, which aim to solve the problem of low flow velocity measuring precision of the existing method.

The invention is realized by the following steps: a multi-channel synchronous emission flow velocity measuring device comprises 2N ultrasonic transducers, wherein N is more than or equal to 3; the N ultrasonic transducers are uniformly distributed on the same cross section of the side wall of the pipeline and are called as a first group of ultrasonic transducers; the other N ultrasonic transducers and the first group of ultrasonic transducers are uniformly distributed on the other cross section of the side wall of the pipeline in the same arrangement mode, and the N ultrasonic transducers are called as a second group of ultrasonic transducers; the N ultrasonic transducers in the first group and the N ultrasonic transducers in the second group are in one-to-one correspondence on the same bus; each ultrasonic transducer in the first group corresponds to the ultrasonic transducer in the second group, and the ultrasonic transducer which is connected with the ultrasonic transducer and intersected with the axial lead can be always found, and the two ultrasonic transducers are called as a pair of ultrasonic transducers; two pairs of ultrasonic transducers can solve a flow velocity, N pairs of ultrasonic transducers can at least solve N/2 and get an integer of flow velocity downwards, and at most can solve N flow velocities; the average flow rate is averaged over all flow rates.

In the process of solving a flow velocity through two pairs of ultrasonic transducers, one pair of ultrasonic transducers is used for measuring the downstream propagation time of the ultrasonic waves in the fluid, and the other pair of ultrasonic transducers is used for measuring the upstream propagation time of the ultrasonic waves in the fluid.

The front end of each ultrasonic transducer is provided with an ultrasonic probe, and each ultrasonic transducer is a transmitting-receiving integrated ultrasonic transducer.

The N ultrasonic transducers on the same cross section are installed and fixed through an additional device which is similar to a bandage structure, threads are arranged on the additional device at equal intervals, and the corresponding ultrasonic probe is fixed through the threads.

The multi-channel synchronous emission flow velocity measuring device further comprises a channel control module and a timing module which are connected with each ultrasonic transducer, wherein the channel control module and the timing module are respectively connected with a single chip microcomputer; the single chip microcomputer is connected with an upper computer through a USB communication module.

Preferably, the channel control module adopts a 74HC4052D chip, the timing module adopts a TDC-GP22 chip, and the single chip microcomputer adopts an MSP430FR6047 chip.

The invention provides a multichannel synchronous emission flow velocity measuring method, which comprises the following steps:

a. arranging 2N ultrasonic transducers on the side wall of the pipeline;

b. under the control of the single chip microcomputer, the channel control module controls the ultrasonic transducers to work simultaneously, wherein one ultrasonic transducer in each pair of ultrasonic transducers is used for transmitting an ultrasonic signal, and the other ultrasonic transducer in each pair of ultrasonic transducers is used for receiving the ultrasonic signal;

c. the channel control module and the timing module collect ultrasonic signals transmitted/received by the ultrasonic probes at the front ends of the ultrasonic transducers and send the collected signals to the single chip microcomputer;

d. the single chip microcomputer stores and processes the received data and sends the corresponding data to an upper computer;

e. the upper computer calculates the flow rate according to the following formula:

in the above formula, T₁Is the downstream propagation time, T, of the ultrasonic signal in the fluid₂The counter-current propagation time of the ultrasonic signals in the fluid is shown, L is the distance between two ultrasonic transducers on the same bus, and theta is the included angle between the connecting line of each pair of ultrasonic transducers and the pipe wall;

one flow velocity v can be solved by two pairs of ultrasonic transducers, and the average value of the flow velocity is solved by solving a plurality of flow velocities.

The invention designs an ultrasonic multichannel synchronous emission flowmeter, realizes multi-probe synchronous water flow velocity measurement, and particularly researches and develops an ultrasonic multichannel synchronous emission flow velocity measurement device and method. The invention integrates the narrow-band Internet of things technology, corresponding data can be uploaded to an upper computer, and the intelligent level of the ultrasonic flowmeter is improved.

The invention designs the integrated chip by using the characteristics of the timing chip and the microcontroller, realizes the remote meter reading function of the remote transmission of the data of the ultrasonic flowmeter, obtains the speed of the fluid by using related operations, and provides a new idea for the measurement of the ultrasonic flow rate. The flow can be calculated by accurately measuring the time difference of the ultrasonic wave on each sound channel along the forward and reverse propagation of the water flow by using a weighted integration method, and the measurement precision is higher. By adopting a multi-sensor multi-channel measurement method, the adaptability to flow field changes can be improved, the influence on measurement caused by uneven flow field distribution can be effectively overcome, and the measurement precision of the flow velocity is improved. On the basis, the flow detection is realized under the condition that the pipeline is not in a continuous flow state, particularly the flow of liquid in the pipeline with small diameter is measured, the problems of flow cutoff, production halt and the like can be avoided, and the economic loss caused by the conventional detection method is reduced.

Drawings

Fig. 1 is a schematic structural diagram of an embodiment of the present invention in which four ultrasonic transducers are provided.

Fig. 2 is a schematic structural diagram of an embodiment of the invention in which sixteen ultrasonic transducers are arranged.

Fig. 3 is a schematic structural diagram of an ultrasonic probe attachment in an embodiment of the present invention.

FIG. 4 is a schematic structural connection diagram of a multi-channel synchronous transmission flow velocity measurement apparatus according to an embodiment of the present invention.

Fig. 5 is a block diagram of a hardware module structure in the embodiment of the present invention.

Detailed Description

The invention is dedicated to an ultrasonic multi-probe synchronous emission flow velocity measuring device, and provides a possibility for realizing two-phase flow parameter detection. In particular, the invention designs an ultrasonic multichannel synchronous emission flowmeter. The design scheme of the hardware is selected, and the design scheme of the hardware for digital signal processing is determined from the aspects of cost, precision and robustness. And MSP430FR6047 with high integration level is used as a core circuit, and corresponding software programming is carried out. In the aspect of algorithm research, a forward-reverse flow transit time method and a cross-correlation time difference algorithm based on waveform positioning are provided.

The flow velocity measurement of the ultrasonic time difference flow meter is based on the speed difference principle. As shown in fig. 1, four ultrasonic transducers, A, B, C, D, are arranged on the side wall of the pipeline, and are all integrated ultrasonic transducers for transmitting and receiving ultrasonic waves, so that the ultrasonic waves can be transmitted and received. The ultrasonic transducers A and C are positioned on the same cross section and are arranged oppositely, namely a connecting line of the ultrasonic transducers A and C passes through the center of the cross section; the ultrasonic transducers B and D are positioned on the same cross section and are oppositely arranged, namely, a connecting line of the ultrasonic transducers B and D passes through the center of the cross section; the ultrasonic transducers A and B are positioned on the same bus of the side wall of the pipeline; ultrasonic transducers C and D are located on the same bus of the pipe sidewall. The front end of the ultrasonic transducer is provided with an ultrasonic probe, when four ultrasonic transducers are installed, the ultrasonic probe and the side wall of the pipeline form a certain included angle, A and D are a pair, B and C are a pair, the A and D probes are opposite, the B and C probes are opposite, a signal emitted by the ultrasonic transducer A can be received by the ultrasonic transducer D, and a signal emitted by the ultrasonic transducer B can be received by the ultrasonic transducer C. The ultrasonic probes do not interfere with each other. Such a set of ultrasonic transducers (comprising two pairs of ultrasonic transducers) is capable of solving for a fluid flow rate.

When the fluid flows downstream, the ultrasonic transducer A emits ultrasonic waves, the ultrasonic waves penetrate through the fluid and are received by the ultrasonic transducer D, and the transit time of the ultrasonic waves is the propagation time of the downstream and is marked as T₁. During the countercurrent, the ultrasonic transducer B emits ultrasonic waves, the ultrasonic waves passing through the pipeline are received by the ultrasonic transducer C, the transit time of the ultrasonic waves at the moment is the propagation time of the countercurrent and is marked as T₂。

The flow rate model of the ultrasonic base meter pipeline is as follows:

model: the transit time and time difference model ignores the radial propagation time of the ultrasonic wave, and the downstream propagation time T of the ultrasonic wave₁：

In the formula:

l is the distance between the ultrasonic transducer A and the ultrasonic transducer B, mm;

c-ultrasonic sound velocity, m/s;

v-flow velocity of fluid, m/s;

theta-the angle between the upper tube wall and the probes A, D, which is set to 60 deg. in this embodiment.

The formula is modified as follows:

countercurrent propagation time T of ultrasonic wave₂：

The formula is modified as follows:

by subtracting the formula (4) from the formula (2), when θ becomes 60 °, it is possible to obtain:

the time difference Δ T of forward and backward flow propagation is:

ΔT＝T₂-T₁ (6)

the flow velocity v is then:

similarly, the multi-channel measurement flow rate can be up to 8 speeds. Less than 4 velocity data can be measured with a diameter of 300mm (DN300), and more than 4 velocity data can be measured with a diameter of 300mm (DN 300).

It is explained here that for the measurement of one flow velocity v two pairs (i.e. 4) of ultrasonic transducers are required. The two flow velocity measurements can adopt 8 ultrasonic transducers or 6 ultrasonic transducers; for two flow rates to be measured using 6 ultrasonic transducers, a pair of ultrasonic transducers is required to be shared in solving for the two flow rates. Therefore, up to three flow rates can be measured with 6 ultrasonic transducers in the present invention. 2-4 flow rates can be measured by adopting 8 ultrasonic transducers; up to 5 flow rates can be measured using 10 ultrasonic transducers. By analogy, 4-8 flow rates can be measured using 16 ultrasonic transducers.

Taking 4 pieces of speed data as an example, when the included angle θ is 60 °, the following formula is given:

the average speed was found to be:

for the above 4 speed data, at least 8 ultrasonic transducers need to be provided, and 16 ultrasonic transducers need to be provided if the sharing is not repeated.

As shown in fig. 2, fig. 2 shows a specific arrangement of 16 ultrasonic transducers. In fig. 2, (a) is a front view, (b) is a plan view, and (c) is a left side view. In the figure, ultrasonic transducers A1, B1, C1, D1, E1, F1, G1 and H1 are on the same cross section of the pipeline, and eight are uniformly distributed on the side wall of the pipeline. A2-H2 are on the other cross section of the pipeline, and eight are arranged uniformly. A1 is on the same generatrix of the duct side wall as a2, B1 is on the same generatrix of the duct side wall as B2, and the others are similar. The a1 transmission signal is received by E2, the B1 transmission signal is received by F2, the C1 transmission signal is received by G2, the D1 transmission signal is received by H2, the a2 transmission signal is received by E1, the B2 transmission signal is received by F1, the C2 transmission signal is received by G1, and the D2 transmission signal is received by H1. A1, a2, E1 and E2, the 4 ultrasonic transducers in a group can measure a flow rate. B1, B2, F1 and F2, the 4 ultrasonic transducers in a group can measure a flow rate. C1, C2, G1 and G2, the 4 ultrasonic transducers in a group can measure a flow rate. D1, D2, H1 and H2, the 4 ultrasonic transducers in a group, can measure a flow rate. These 4 flow rates were measured without sharing any pair of ultrasonic transducers. At different flow rate measurements, up to 8 sets of flow rates can be measured if the ultrasonic transducers are shared. When the number of the ultrasonic transducers arranged on the pipe diameter is not enough, the common ultrasonic transducer can be selected when different flow velocities are measured. When the pipe diameter is large and enough ultrasonic transducers can be arranged, different ultrasonic transducers can be selected when different flow velocities are measured.

When each flow velocity is measured, 4 ultrasonic transducers are needed, the 4 ultrasonic transducers are divided into two pairs, and a connecting line of each pair of ultrasonic transducers is intersected with an axial lead, namely, each pair of ultrasonic transducers is symmetrically arranged around the axial lead. Two pairs of ultrasonic transducers, one pair for measuring downstream transit time T₁The other pair is used for measuring the countercurrent transit time T₂. In the two pairs of ultrasonic transducers, the distance between the ultrasonic transducers on the same bus is L, because the flow velocity can be obtained according to the formula (7).

The connecting line between the two ultrasonic transducers in each pair forms a specific angle theta with the pipe wall (namely, the axial direction), the value range of the theta is 10-80 degrees, the formula (7) is obtained under the condition that the value of the theta is 60 degrees, and when the theta is uncertain, the flow velocity solving formula is as follows:

for ultrasonic transducers on the same cross section, an additional device is adopted to fix each probe. As shown in fig. 3, the additional device is similar to a bandage structure, the length of the additional device is adjustable, the longest length is the pipe diameter x pi, threads are arranged at equal intervals, and the ultrasonic probe is fixed through the threads.

As shown in fig. 4, fig. 4 is a structural connection diagram showing the whole flow rate measuring device of the present invention. In the figure, a plurality of ultrasonic probes 3 are uniformly distributed on the side wall of a pipeline 2, and the ultrasonic probes 3 are fixed by an additional device 1 (the specific structure is shown in figure 3). Each ultrasonic probe 3 is connected with the hardware module through an ultrasonic connecting wire harness, the power supply supplies power to the hardware module through a power supply connecting wire, and the hardware module is connected with a computer host through a USB connecting wire.

The hardware module of the present invention includes a single chip microcomputer, a channel control module and a timing module, wherein the single chip microcomputer employs an MSP430FR6047 chip, the channel control module employs a 74HC4052D chip, and the timing module employs a TDC-GP22 timing chip, as shown in fig. 5. The whole system is provided with a chip MSP430F5528 with USB connection and debugging functions.

The single chip microcomputer is connected with the channel control module, and under the control of the single chip microcomputer, the channel control module controls all groups of ultrasonic probes to carry out ultrasonic emission and receives corresponding echo signals to the single chip microcomputer. That is, the channel control module may control connection, disconnection, and switching of the ultrasonic transducers, and may enable the ultrasonic transducers to operate simultaneously, or enable the ultrasonic transducers to operate individually, or select several groups of the ultrasonic transducers to operate. The timing module collects ultrasonic signals and performs timing, the timing signals are sent to the single chip microcomputer, the single chip microcomputer uploads data to the computer host through the USB communication module, and the computer host calculates the flow rate according to a corresponding formula.

The working process is described by taking one path of ultrasonic waves (A and D in FIG. 1) as an example: after the ultrasonic transducer starts to work, the ultrasonic probe A on the pipe wall on one side transmits an acoustic signal, the ultrasonic probe D on the other side receives the acoustic signal, and after the channel control module and the timing module receive the ultrasonic signal, the channel control module controls the ultrasonic probe A not to transmit the acoustic signal, namely, the ultrasonic signal is interrupted, and the ultrasonic signal is not transmitted or received any more during the interruption. The ultrasonic signal is transmitted to the singlechip through the channel control module and the timing module. And after the interruption is finished, the channel control module continues to control the ultrasonic probe to transmit ultrasonic signals, and the signal intensity transmitted in the next step can be adjusted according to the size of the transmitted and received signals. The channel control module and the timing module collect and transmit multi-channel acoustic signals to the single chip microcomputer, the single chip microcomputer transmits the processed data to an upper computer, and the processed data are processed by a corresponding software system in the upper computer, so that the processed average speed is obtained finally.

Embodiment 1, a multi-channel synchronous emission flow velocity measuring device

The flow velocity measuring device provided by the invention comprises an even number of ultrasonic transducers, and the number of the ultrasonic transducers is between 6 and 32.

The explanation will be given by taking 16 ultrasonic transducers in fig. 2 as an example. The 16 ultrasonic transducers are evenly divided into two groups, wherein the first group of ultrasonic transducers comprises A1-H1, and the 8 ultrasonic transducers are uniformly distributed on the same cross section of the side wall of the pipeline in sequence of A1-H1; the second group of ultrasonic transducers comprises A2-H2, and the 8 ultrasonic transducers are uniformly distributed on the other cross section of the side wall of the pipeline in the sequence of A2-H2. Moreover, the ultrasonic transducers in the two groups correspond to each other on the pipeline bus one by one, namely: a1 is on the same bus as a2, B1 is on the same bus as B2, and so on.

In the first group of ultrasonic transducers, A1-D1 transmits ultrasonic signals, and in the second group of ultrasonic transducers, E2-H2 which are respectively and symmetrically distributed with A1-D1 about a point on the axis line with equal distance from the two cross sections are used for receiving the ultrasonic signals transmitted by A1-D1. In the second group of ultrasonic transducers, A2-D2 emits ultrasonic signals, the ultrasonic signals emitted by A2-D2 are respectively received by E1-H1 in the first group, and E1-H1 are respectively and symmetrically distributed with respect to points A2-D2 on the axis line, which are equidistant from the two cross sections.

The front end of each ultrasonic transducer is provided with an ultrasonic probe, and when the ultrasonic transducers are fixed on the side wall of the pipeline, the ultrasonic probes are fixed by adopting an additional device shown in figure 3.

During measurement, one ultrasonic probe in the first group transmits an ultrasonic signal which is received by one ultrasonic probe in the second group which is symmetrical to the ultrasonic probe about the axis, and the two ultrasonic probes are called as a pair of ultrasonic probes; in another pair of ultrasonic probes on the same bus as the pair of ultrasonic probes, the ultrasonic probes in the second group transmit ultrasonic signals which are received by the ultrasonic probes in the first group; the two pairs of ultrasonic probes can calculate a flow velocity by measuring the time difference between the forward flow and the reverse flow, and combining the distance between the two ultrasonic probes on the same bus and the included angle between the pair of ultrasonic probes and the pipe wall by using a formula (13). Similarly, a flow rate can be determined by using two pairs of ultrasonic probes. In fig. 2, if the ultrasonic transducers are not reused, at least 4 flow rates can be obtained, and at most 8 flow rates can be obtained, and then the average value of the flow rates can be obtained by using the average formula.

The channel control module can control all the ultrasonic transducers to work simultaneously and can also control some ultrasonic transducers to work. The timing module is used for acquiring ultrasonic signals and timing. The singlechip receives and processes signals sent by the channel control module and the timing module, and the singlechip can upload corresponding data to a computer host through the USB communication module. The computer host can calculate the average flow speed according to the corresponding software program.

Embodiment 2, a method for measuring multi-channel synchronous emission flow velocity

The explanation will be given by taking 16 ultrasonic transducers in fig. 2 as an example. The multichannel synchronous emission flow velocity measuring method provided by the invention comprises the following steps:

a, 16 ultrasonic transducers are arranged on the side wall of the pipeline, and an ultrasonic probe is arranged at the front end of each ultrasonic transducer. The arrangement of the ultrasonic transducers is shown in fig. 2 and described above.

b, under the control of the channel control module, each ultrasonic transducer transmits an ultrasonic signal through an ultrasonic probe, the ultrasonic signal is transmitted to the single chip microcomputer through the channel control module and the timing module and then transmitted to the computer host through the single chip microcomputer, and finally the computer host calculates the fluid flow rate according to a corresponding formula.