CN112097843B - High-sensitivity ultrasonic flowmeter based on ultrasonic transducer and method thereof - Google Patents

High-sensitivity ultrasonic flowmeter based on ultrasonic transducer and method thereof Download PDF

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CN112097843B
CN112097843B CN202010981127.1A CN202010981127A CN112097843B CN 112097843 B CN112097843 B CN 112097843B CN 202010981127 A CN202010981127 A CN 202010981127A CN 112097843 B CN112097843 B CN 112097843B
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ultrasonic
section
middle section
transducer
fluid
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CN112097843A (en
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谢金
朱可
陈旭颖
杨邓飞
屈梦娇
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Zhejiang University ZJU
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
    • G01F1/662—Constructional details
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F15/00—Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus
    • G01F15/18—Supports or connecting means for meters
    • G01F15/185—Connecting means, e.g. bypass conduits

Abstract

The invention discloses a high-sensitivity ultrasonic flowmeter based on an ultrasonic transducer and a method thereof, wherein the flowmeter comprises an inlet section, a middle section and an outlet section which are sequentially communicated, and the inlet section, the middle section and the outlet section are straight pipe sections; the axes of the inlet section and the outlet section form an angle with the axis of the middle section; two end points of the middle section are closed, and are respectively provided with an ultrasonic transducer integrating receiving and transmitting; the array receivers of the two ultrasonic transducers are oppositely arranged and can transmit and receive ultrasonic signals mutually; the communication positions of the inlet section and the outlet section with the middle section are respectively positioned on the inner side of the ultrasonic transducer at the end point of the middle section, and an interval is arranged between the two communication positions along the length direction of the middle section, so that the propagation path of the ultrasonic wave and the flow path of the fluid in the middle section have overlapped sections. The invention adopts a structure that the sound wave propagation path is superposed with the fluid flow path, and can greatly improve the sensitivity of the flowmeter.

Description

High-sensitivity ultrasonic flowmeter based on ultrasonic transducer and method thereof
Technical Field
The invention belongs to the technical field of flow measurement, and particularly relates to a high-sensitivity ultrasonic flowmeter based on an ultrasonic transducer and a method thereof.
Background
Fluid flow metering has a wide range of practical applications. Among various types of flow meters, the ultrasonic flow meter has the advantages of high precision, high response speed, large range ratio, small pressure loss and the like, which also increases the market demand of the ultrasonic flow meter.
The traditional ultrasonic flowmeter mostly adopts a piezoelectric ultrasonic transducer, and the volume is large, so that the flow measurement of small pipe diameter is difficult to carry out. And the traditional ultrasonic flowmeter usually arranges the ultrasonic transducers to the two sides of the pipeline directly, and the propagation path of ultrasonic waves in a fluid medium is short, so that the sensitivity of the flowmeter is low.
The micro-mechanical piezoelectric ultrasonic transducer processed by the MEMS technology has the advantages of small volume and low power consumption, and has wide application prospect in the aspect of ultrasonic flow measurement of small pipe flow fluid. Therefore, it is necessary to design a high-sensitivity ultrasonic flowmeter based on a micromechanical piezoelectric ultrasonic transducer.
Disclosure of Invention
The invention aims to overcome the problems of large volume, difficult integration, low sensitivity and the like of a flow meter in the prior art, and provides a high-sensitivity ultrasonic flow meter based on an ultrasonic transducer and a method thereof.
The invention adopts the following specific technical scheme:
a high-sensitivity ultrasonic flowmeter based on an ultrasonic transducer comprises an inlet section, a middle section and an outlet section which are communicated in sequence, wherein the inlet section, the middle section and the outlet section are straight pipe sections; the axes of the inlet section and the outlet section form an angle with the axis of the middle section; two end points of the middle section are closed, and are respectively provided with an ultrasonic transducer integrating receiving and transmitting; the array receivers of the two ultrasonic transducers are oppositely arranged and can transmit and receive ultrasonic signals mutually; the communication positions of the inlet section and the outlet section with the middle section are respectively positioned on the inner side of the ultrasonic transducer at the end point of the middle section, and an interval is arranged between the two communication positions along the length direction of the middle section, so that the propagation path of the ultrasonic wave and the flow path of the fluid in the middle section have overlapped sections.
Preferably, the ultrasonic transducer is a micromechanical piezoelectric ultrasonic transducer.
Furthermore, the micromechanical piezoelectric ultrasonic transducer comprises a transducer unit formed by laminating a bottom electrode, a piezoelectric layer and an upper electrode layer by layer; the micromechanical piezoelectric ultrasonic transducer has multiple transducer units, and the transducer units are arranged in parallel.
Further, the number of the transducer units is 25, and the 25 transducer units are arranged in a 5 × 5 uniform rectangular array.
Preferably, the transducer unit is communicated with an external signal excitation source through a lead.
Preferably, the axes of the inlet and outlet sections are parallel to each other.
Preferably, the inlet section and the outlet section are centrosymmetric about a center point of the middle section.
Another object of the present invention is to provide a method for measuring a fluid flow rate based on any one of the above high-sensitivity ultrasonic flow meters, which includes the following steps:
s1: ultrasonic pulses are respectively transmitted along the downstream direction and the upstream direction of the fluid by controlling two ultrasonic transducers at the middle section to obtain the downstream transit time t1And a countercurrent transit time t2；
S2: by downstream transit time t1And a countercurrent transit time t2Calculating the difference delta t between the two to obtain the average flow velocity of the fluid in the pipeline
Figure BDA0002687549660000021
Figure BDA0002687549660000022
And further through
Figure BDA0002687549660000023
The instantaneous flow rate Q of the fluid is obtained,
Figure BDA0002687549660000024
wherein c is the propagation speed of the ultrasonic wave in the fluid, L is the effective length of the sound wave, and D is the diameter of the middle section pipeline.
Compared with the prior art, the invention has the following beneficial effects:
1) in the conventional ultrasonic flowmeter, ultrasonic transducers are usually arranged on two sides of a pipeline (as shown in fig. 3), the propagation path of ultrasonic waves in a fluid medium is short, and the effective length L of sound waves is short, so that the sensitivity of the flowmeter is low; according to the invention, the flowmeter pipeline is divided into three sections by bending, the ultrasonic transducers are arranged at two ends of the middle section pipeline, and a structure that the sound wave propagation path and the fluid flow path are partially overlapped is adopted, so that the size of L can be effectively increased, a larger delta t can be obtained under the same flow, and the sensitivity of the flowmeter is improved;
2) the invention can be used for measuring the flow of gas and liquid;
3) the size of the L is not limited by the diameter of the pipeline, so that the L can be freely adjusted according to the requirement on the sensitivity of the flowmeter to adapt to different application occasions.
Drawings
FIG. 1 is a schematic structural view of a high sensitivity ultrasonic flow meter of the present invention;
FIG. 2 is a schematic structural diagram of an ultrasonic transducer of the present invention;
FIG. 3 is a schematic structural diagram of a conventional ultrasonic flow meter;
in the figure: upper electrode 1, piezoelectric layer 2, bottom electrode 3, basal layer 4.
Detailed Description
The invention will be further elucidated and described with reference to the drawings and the detailed description. The technical features of the embodiments of the present invention can be combined correspondingly without mutual conflict.
As shown in fig. 1, the present invention provides a high-sensitivity ultrasonic flowmeter based on an ultrasonic transducer, which includes an inlet section, a middle section and an outlet section that are sequentially communicated, wherein the inlet section, the middle section and the outlet section are all straight pipe sections, and fluid can enter the high-sensitivity ultrasonic flowmeter through the inlet section and flow out from the outlet section through the middle section.
The axis of the inlet section and the axis of the middle section have an angle therebetween, the axis of the outlet section and the axis of the middle section have a certain angle therebetween, and the angles between the two and the axis of the middle section can be the same or different. However, in order to ensure that the fluid flows stably in the high-sensitivity ultrasonic flow meter of the present invention, it is preferable to set the angles of both to be the same. In addition, the inlet section and the outlet section may be directly arranged in a centrosymmetric structure with respect to a center point of the middle section.
The two end points of the middle section are closed, and the two closed end points are respectively provided with a transmitting-receiving integrated ultrasonic transducer T1 and a T2. The array receivers of the two ultrasonic transducers are oppositely arranged and can transmit and receive ultrasonic signals to each other. The communication positions of the inlet section, the outlet section and the middle section are respectively positioned at the inner sides of the ultrasonic transducers at the end points of the middle section, and the inner sides of the ultrasonic transducers are the inner sides close to the middle point of the middle section. The two connections are spaced apart from each other along the length of the intermediate section so that the propagation path of the ultrasonic wave and the flow path of the fluid in the intermediate section have a coincident section therebetween.
As shown in fig. 2, in the present embodiment, the ultrasonic transducers T1 and T2 may be micromechanical piezoelectric ultrasonic transducers. The bottom of the micro-mechanical piezoelectric ultrasonic transducer is a substrate layer 4, 25 transducer units are arranged on the substrate layer 4, and the 25 transducer units are arranged in a uniform rectangular array of 5 multiplied by 5 on the upper surface of the substrate layer 4. Each transducer unit is formed by stacking a bottom electrode 3, a piezoelectric layer 2 and an upper electrode 1 layer by layer. In this embodiment, each transducer unit is connected to a wire in parallel, the upper electrodes 1 of all transducer units on the same micromechanical piezoelectric ultrasonic transducer are connected to one end of the wire, and the bottom electrodes 3 of all transducer units are connected to the other end of the wire. When the sound waves are transmitted, the sound waves are connected with an external signal excitation source through a lead, and excitation signals are applied to all transducer units; when receiving the sound wave, each transducer unit outputs the received signal outwards through the lead.
The method for measuring the fluid flow based on the high-sensitivity ultrasonic flowmeter comprises the following specific steps:
s1: ultrasonic pulses are emitted in the downstream direction of the fluid by means of an ultrasonic transducer T1, then received by means of an ultrasonic transducer T2, and the downstream transit time T is recorded at this time1。
Ultrasonic pulses are emitted in the countercurrent flow direction by means of the ultrasonic transducer T2, then received by means of the ultrasonic transducer T1, and the countercurrent transit time T is recorded2。
S2: by downstream transit time t1And a countercurrent transit time t2Calculating the difference delta t between the two to obtain the average flow velocity of the fluid in the pipeline
Figure BDA0002687549660000041
Figure BDA0002687549660000042
And further through
Figure BDA0002687549660000043
The instantaneous flow rate Q of the fluid is obtained,
Figure BDA0002687549660000044
wherein c is the propagation speed of the ultrasonic wave in the fluid, L is the effective length of the sound wave, and D is the diameter of the middle section pipeline.
The measurement principle of the invention is briefly described below:
when the ultrasonic wave propagates in the same direction as the fluid (i.e., downstream), the propagation speed increases and the corresponding propagation time becomes shorter. When the propagation direction of the ultrasonic wave is opposite to the fluid flowing direction (i.e. counter-current), the propagation speed will be slow, and the corresponding propagation time will also be long. By measuring the propagation transit time of the ultrasonic wave in the forward flow state and the reverse flow state, the average flow velocity of the fluid in the pipeline can be calculated. And then according to the diameter D of the flowmeter pipeline, the instantaneous flow of the fluid passing through the flowmeter can be calculated.
Forward flow transit time t1And a countercurrent transit time t2And their difference Δ t are calculated as follows:
Figure BDA0002687549660000045
Figure BDA0002687549660000046
Figure BDA0002687549660000047
in the above formula, the effective length L of the acoustic wave is used instead of the total propagation path length of the acoustic wave, because it can be considered that the propagation speed of the acoustic wave is influenced by the fluid flow only in this section of the path, and the propagation time of the remaining path is cancelled out by the difference in formula (3).
The propagation speed c of the ultrasonic wave in the fluid body is generally far greater than the average speed of the fluid in the pipeline
Figure BDA0002687549660000054
Therefore, equation (3) can be simplified as:
Figure BDA0002687549660000051
thus, according to the downstream transit time t1And a countercurrent transit time t2The difference Δ t, the average flow velocity of the fluid in the pipe can be calculated:
Figure 1
if the diameter D of the middle section pipe is known, the instantaneous flow Q of the fluid in the pipe can be calculated:
Figure BDA0002687549660000053
conventional ultrasonic flow meters tend to place ultrasonic transducers directly on both sides of the pipe (as shown in fig. 3), the propagation path of ultrasonic waves in the fluid medium is short, and the effective length L of the acoustic wave is small, resulting in low meter sensitivity. According to the invention, the flowmeter pipeline is divided into three sections by bending, the ultrasonic transducers are arranged at two ends of the middle section pipeline, and a structure that the sound wave propagation path and the fluid flow path are partially overlapped is adopted, so that the size of L can be effectively increased, a larger delta t can be obtained under the same flow, and the sensitivity of the flowmeter is improved.
Examples
The flow rate of liquid paraffin oil was measured at room temperature using a conventional ultrasonic flowmeter (θ 45 °, D8 mm, and L D/sin θ, as shown in fig. 3) and a high-sensitivity ultrasonic flowmeter of the present invention (D8 mm, L150 mm, as shown in fig. 1), respectively. Where θ denotes an angle between a propagation path of the ultrasonic wave and a flow path of the fluid in the intermediate section, and in the present invention, this angle θ is 0 °.
As a result, it was found that: the test sensitivity of the traditional ultrasonic flowmeter is 3.5 ns.min/L, and the test sensitivity of the high-sensitivity ultrasonic flowmeter is 85.6 ns.min/L.
The above-described embodiments are merely preferred embodiments of the present invention, which should not be construed as limiting the invention. Various changes and modifications may be made by one of ordinary skill in the pertinent art without departing from the spirit and scope of the present invention. Therefore, the technical scheme obtained by adopting the mode of equivalent replacement or equivalent transformation is within the protection scope of the invention.

Claims (8)

1. A high-sensitivity ultrasonic flowmeter based on an ultrasonic transducer is characterized by comprising an inlet section, a middle section and an outlet section which are sequentially communicated, wherein the inlet section, the middle section and the outlet section are straight pipe sections; the axes of the inlet section and the outlet section form an angle with the axis of the middle section; two end points of the middle section are closed, and are respectively provided with an ultrasonic transducer integrating receiving and transmitting; the array receivers of the two ultrasonic transducers are oppositely arranged and can transmit and receive ultrasonic signals mutually; the communication positions of the inlet section and the outlet section with the middle section are respectively positioned on the inner side of the ultrasonic transducer at the end point of the middle section, and an interval is arranged between the two communication positions along the length direction of the middle section, so that the propagation path of the ultrasonic wave and the flow path of the fluid in the middle section have overlapped sections.
2. The high sensitivity ultrasonic flow meter of claim 1, wherein the ultrasonic transducer is a micromachined piezoelectric ultrasonic transducer.
3. The high sensitivity ultrasonic flow meter according to claim 2, wherein the micromachined piezoelectric ultrasonic transducer comprises a transducer unit formed by stacking a bottom electrode (3), a piezoelectric layer (2) and an upper electrode (1) layer by layer; the micromechanical piezoelectric ultrasonic transducer has multiple transducer units, and the transducer units are arranged in parallel.
4. The high sensitivity ultrasonic flow meter of claim 3, wherein the number of transducer elements is 25, and the 25 transducer elements are arranged in a 5 x 5 uniform rectangular array.
5. The high sensitivity ultrasonic flow meter according to claim 3 or 4, wherein the transducer unit is in communication with an external signal excitation source through a wire.
6. The high sensitivity ultrasonic flow meter of claim 1, wherein the axes of the inlet and outlet sections are parallel to each other.
7. The high sensitivity ultrasonic flow meter of claim 1, wherein the inlet section and the outlet section are centrosymmetric about a center point of the intermediate section.
8. A method for measuring fluid flow based on the high-sensitivity ultrasonic flowmeter of any claim 1-7 is characterized by comprising the following steps:
s1: ultrasonic pulses are respectively transmitted along the downstream direction and the upstream direction of the fluid by controlling two ultrasonic transducers at the middle section to obtain the downstream transit time t1And a countercurrent transit time t2；
S2: by downstream transit time t1And a countercurrent transit time t2Calculating the difference delta t between the two to obtain the average flow velocity of the fluid in the pipeline
Figure FDA0002687549650000011
Figure FDA0002687549650000021
And further through
Figure FDA0002687549650000022
The instantaneous flow rate Q of the fluid is obtained,
Figure FDA0002687549650000023
wherein c is the propagation speed of the ultrasonic wave in the fluid, L is the effective length of the sound wave, and D is the diameter of the middle section pipeline.
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101004353A (en) * 2007-01-16 2007-07-25 中国计量学院 Detection method of time difference cross in use for ultrasonic flowmeter
CN109798944A (en) * 2018-12-25 2019-05-24 浙江大学 Flowmeter and transition time measuring device based on micromechanics piezoelectric supersonic wave transducer
CN209166556U (en) * 2018-12-25 2019-07-26 浙江大学 Flowmeter transition time measuring device based on micromechanics piezoelectric supersonic wave transducer

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DE102005041288A1 (en) * 2005-08-31 2007-03-01 GEMÜ Gebr. Müller Apparatebau GmbH & Co. KG Flow meter for measuring flow rate of a fluid flowing through a conduit using ultrasound

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101004353A (en) * 2007-01-16 2007-07-25 中国计量学院 Detection method of time difference cross in use for ultrasonic flowmeter
CN109798944A (en) * 2018-12-25 2019-05-24 浙江大学 Flowmeter and transition time measuring device based on micromechanics piezoelectric supersonic wave transducer
CN209166556U (en) * 2018-12-25 2019-07-26 浙江大学 Flowmeter transition time measuring device based on micromechanics piezoelectric supersonic wave transducer

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