CN113933534A - Device and method for measuring liquid flowing speed of non-full pipe flow - Google Patents
Device and method for measuring liquid flowing speed of non-full pipe flow Download PDFInfo
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- CN113933534A CN113933534A CN202111115602.8A CN202111115602A CN113933534A CN 113933534 A CN113933534 A CN 113933534A CN 202111115602 A CN202111115602 A CN 202111115602A CN 113933534 A CN113933534 A CN 113933534A
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- 238000000691 measurement method Methods 0.000 abstract description 6
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
- G01P5/08—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring variation of an electric variable directly affected by the flow, e.g. by using dynamo-electric effect
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Abstract
The invention discloses a device for measuring the flowing speed of liquid in non-full pipe flow, which comprises an excitation electrode and a detection electrode which are arranged on the outer wall of an insulating pipeline, wherein the excitation electrode is electrically connected with a signal generator through a lead, and the detection electrode is sequentially connected with a color ring inductor, a signal processing circuit, a data acquisition card and a computer through leads. According to the device for measuring the flowing speed of the liquid in the non-full pipe, the capacitive coupling non-contact conductivity measurement technology and the spatial filtering speed measurement method are combined, and the problem that the flowing speed of the liquid in the non-full pipe is difficult to measure in the prior art is solved. The invention also discloses a method for measuring the liquid flow speed of the non-full pipe flow.
Description
Technical Field
The invention belongs to the technical field of liquid flow velocity measurement, relates to a device for measuring the liquid flow velocity of non-full pipe flow, and further relates to a method for measuring the liquid flow velocity of the non-full pipe flow.
Background
The measurement of liquid flow rate is widely existed in daily life and industrial control, such as the control of flow rate and flow rate of water works, the accurate measurement of water injection rate and flow rate of water injection system under oil well, etc. In recent years, the measurement of liquid flow parameters in miniaturized industrial equipment has received much attention. Due to the fact that the inner diameter of the pipeline in the miniaturized device is reduced, the surface tension effect of water becomes more prominent, and therefore, some theories obtained under the conventional pipe diameter are not suitable for detecting the fluid in the small channel any more.
At present, the commonly used detection means in the field of small-channel liquid flow velocity measurement mainly comprise an ultrasonic method, a high-speed photography method, a conductivity measurement method and the like. Compared with a conductance measurement method, the former two methods not only have special requirements on detection environment, but also have higher cost and are difficult to apply in actual industry. The conductivity measuring method is simple in device and low in cost, and is commonly applied to the field of liquid flow velocity measurement. However, most of the traditional conductivity measurement methods are contact conductivity detection, and the electrode is in direct contact with the solution to be detected, which easily causes problems of electrode polarization, electrochemical corrosion and the like.
Capacitive Coupled Contactless Conductivity Detection (C)4D) The method is a novel non-contact measurement technology, and the detection electrode of the method is not in direct contact with the liquid to be detected, so that the problems in the traditional contact type conductivity detection can be effectively solved. At present, the research of applying the technology to flow velocity measurement is only limited to be realized by adopting a cross-correlation method, which not only has special requirements on the structure of a sensor, but also requires that upstream and downstream signals have consistency in terms of the cross-correlation method, so that the method has higher requirements on the stability of the liquid flowing state. For non-full pipe flow, the liquid is changed in form continuously in the flowing process, the output electric signal is changed along with the change, the consistency of the upstream and downstream output signals is difficult to ensure, and the measurement of the liquid flow rate is difficult to realize.
Disclosure of Invention
The invention aims to provide a device for measuring the flowing speed of liquid in a non-full pipe, which combines a capacitive coupling non-contact conductivity measurement technology with a spatial filtering speed measurement method and solves the problem that the flowing speed of the liquid in the non-full pipe is difficult to measure in the prior art.
It is another object of the present invention to provide a method for measuring the flow rate of a non-full pipe flow liquid.
The invention adopts the technical scheme that the device for measuring the flowing speed of the liquid in the non-full pipe flow comprises an excitation electrode and a detection electrode which are arranged on the outer wall of an insulated pipeline, wherein the excitation electrode is connected with a signal generator through a lead, and the detection electrode is sequentially connected with a color ring inductor, a signal processing circuit, a data acquisition card and a computer through leads.
Preferably, the signal processing circuit comprises a current voltage conversion circuit, a full-wave rectification circuit and a low-pass filter circuit which are sequentially connected through a lead, and the color ring inductor and the data acquisition card are respectively connected with the current voltage conversion circuit and the low-pass filter circuit.
The invention adopts another technical scheme that a method for measuring the liquid flowing speed of the non-full pipe flow adopts the device for measuring the liquid flowing speed of the non-full pipe flow, and the method specifically comprises the following steps:
the signal generator outputs an alternating current voltage with a certain frequency to be applied to the excitation electrode, at the moment, an alternating current path is formed by the excitation electrode, the detection electrode and a conductive solution between the excitation electrode and the detection electrode, an alternating current signal containing solution conductivity information is output from the detection electrode and is connected with the chromatic circle inductor in series, the inductive reactance of the inductor is utilized to offset the capacitive reactance of the coupling capacitor to eliminate the influence of the coupling capacitor, then the alternating current signal passes through the current-voltage conversion circuit, the full-wave rectifying circuit and the low-pass filtering circuit to output a direct current voltage signal convenient to collect, the direct current voltage signal is collected by the data collecting card and transmitted to the computer for data processing, the computer carries out trend removing item processing on the output voltage signal to eliminate the interference of the measuring environment, carries out Fourier transformation on the processed voltage signal to obtain a frequency spectrogram of the voltage signal, and obtains the frequency f of the signal through the frequency spectrogramiAnd amplitude hiThen according to the frequency f of the signaliAnd amplitude hiAnd calculating the equivalent peak frequency, and calculating the flow rate of the liquid according to the mathematical expression of the liquid flow speed and the equivalent peak frequency.
Preferably, the frequency of the signal generator output voltage is a resonance frequency.
Preferably, the equivalent peak frequency is calculated according to the following formula:
wherein: f. ofeIs the equivalent peak frequency, fiFor obtaining the frequency f of a signal by means of a spectrogrami，hiIs a frequency fiThe corresponding amplitude, i, is the number of points in the spectral analysis.
Preferably, the mathematical expression of the liquid flow velocity and the equivalent peak frequency is calculated according to the following formula:
v＝kfe (2)
wherein k is a dimensionless correction coefficient in velocity measurement, and is calibrated by experiments, and v is the liquid flow velocity.
The invention has the beneficial effects that:
(1) the invention adopts a space filtering speed measurement method, so that the capacitance coupling non-contact type conductivity detection technology can realize the measurement of the liquid flow speed in a non-full pipe state;
(2) the measuring mode of the invention is non-contact, which can effectively avoid the problems of electrode polarization, corrosion and the like, prolong the service life of the electrode and simultaneously improve the measuring precision;
(3) the invention can be realized by using a sensor with a two-ring electrode structure: simple structure, small volume, low cost and more convenient application in complex industrial environment.
Drawings
FIG. 1 is a schematic diagram of a non-full pipe flow liquid flow rate measurement device according to the present invention;
FIG. 2 is a schematic diagram of a capacitive coupling non-contact conductivity sensor in a device for measuring the flow rate of a liquid in a non-full pipe flow according to the present invention;
FIG. 3 is a graph of spatial sensitivity profiles of capacitively coupled non-contact conductivity detection sensors in a non-full pipe flow liquid flow rate measurement apparatus of the present invention;
FIG. 4 is a graph of the spectrum of the output voltage signal of the detection electrode of the present invention;
fig. 5 is a graph of the relationship between the reference velocity and the equivalent peak frequency of the present invention.
In the figure, 1 is an insulating pipeline, 2 is an exciting electrode, 3 is a detecting electrode, 4 is a signal generator, 5 is a color ring inductor, 6 is a signal processing circuit, 6-1 is a current-voltage conversion circuit, 6-2 is a full-wave rectification circuit, 6-3 is a low-pass filter circuit, 7 is a data acquisition card, and 8 is a computer.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
The invention discloses a device for measuring the flowing speed of liquid in non-full pipe flow, which has a structure shown in figure 1 and comprises an excitation electrode 2 and a detection electrode 3 which are arranged on the outer wall of an insulated pipeline 1, wherein the excitation electrode 2 is connected with a signal generator 4 through a lead, and the detection electrode 3 is sequentially connected with a color ring inductor 5, a signal processing circuit 6, a data acquisition card 7 and a computer 8 through leads.
Preferably, the signal processing circuit 6 comprises a current-voltage conversion circuit 6-1, a full-wave rectification circuit 6-2 and a low-pass filter circuit 6-3 which are connected in sequence through conducting wires, and the color ring inductor 5 and the data acquisition card 7 are respectively connected with the current-voltage conversion circuit 6-1 and the low-pass filter circuit 6-3.
The invention adopts another technical scheme that a method for measuring the liquid flowing speed of the non-full pipe flow adopts the device for measuring the liquid flowing speed of the non-full pipe flow, and the method specifically comprises the following steps:
the signal generator 4 outputs an alternating current voltage with a certain frequency to be applied to the excitation electrode 2, at the moment, an alternating current path is formed by the excitation electrode 2, the detection electrode 3 and a conductive solution between the excitation electrode 2 and the detection electrode 3, an alternating current signal containing solution conductivity information is output on the detection electrode 3 and is connected with the color ring inductor 5 in series, the inductive reactance of the inductor is utilized to offset the capacitive reactance of the coupling capacitor, the influence of the coupling capacitor is eliminated, then the alternating current signal passes through the current-voltage conversion circuit 6-1, the full-wave rectification circuit 6-2 and the low-pass filter circuit 6-3, then a direct current voltage signal which is convenient to collect is output, the direct current voltage signal is collected by the data collection card 7 and transmitted to the computer 8 for data processing, the computer 8 carries out trend item removing processing on the output voltage signal, eliminates the interference of a measuring environment, and carries out Fourier transform on the processed voltage signal to obtain a frequency spectrum diagram thereof, as shown in fig. 4, is the frequency of a set of output voltage signalsSpectrogram, obtaining frequency f of signal by spectrogramiAnd amplitude hiThen according to the frequency f of the signaliAnd amplitude hiAnd calculating the equivalent peak frequency, and calculating the flow rate of the liquid according to the mathematical expression of the liquid flow speed and the equivalent peak frequency.
Preferably, the frequency of the output voltage of the signal generator (4) is a resonance frequency.
Preferably, the equivalent peak frequency is calculated according to the following formula:
wherein: f. ofeIs the equivalent peak frequency, fiFor obtaining the frequency f of a signal by means of a spectrogrami，hiIs a frequency fiThe corresponding amplitude, i, is the number of points in the spectral analysis.
Preferably, the mathematical expression of the liquid flow velocity and the equivalent peak frequency is calculated according to the following formula:
v＝kfe (2)
wherein k is a dimensionless correction coefficient in velocity measurement, and is calibrated by experiments, and v is the liquid flow velocity.
As shown in FIG. 2, w1、w2The widths of the excitation electrode 2 and the detection electrode 3, respectively, and the distance d between the two electrodeswR1 and R2 are respectively the inner diameter and the outer diameter of the insulated pipe 1, wherein w1＝w2＝dw20mm, 14mm for R1, 16mm for R2, and the exciting electrode 2 and the detecting electrode 3 are both ring structures and are installed on the outer wall of the insulated pipeline 1.
The non-contact type capacitive coupling conductivity detection sensor is formed by an insulated pipeline, an exciting electrode and a detection electrode.
As shown in FIG. 3, when the liquid fluctuates through the sensor, the axial spatial sensitivity distribution of the sensor approximates to a Gaussian pulse function distribution and reaches a peak at the center of the sensor, wherein r represents the position distance of the liquid fluctuation relative to the center of the sensor.
Fig. 5 is a relationship between the equivalent peak frequency and the velocity obtained in the experiment, and in order to accurately verify the relationship between the velocity and the equivalent peak frequency, the device is used for carrying out the experiment on four groups of liquids at different velocities, and fitting analysis is carried out, so that the reference velocity and the equivalent peak frequency show a good linear relationship, and the experimental result is matched with the velocity calculation formula (2) obtained in the theoretical part. The line in the graph is a straight line fitting the equivalent peak frequency and the speed, and the black dots represent the corresponding equivalent peak frequencies at different speeds.
The invention carries out experimental measurement on the flowing speed of the tap water through the gravity conveying platform, tests the condition that the liquid speed range is 1.39-2.35m/s by using the method provided by the invention, obtains the good effect that the absolute error of continuous repeated measurement is less than 5 percent, and realizes the measurement of the flowing speed of the liquid in a non-coherent state.
Claims (6)
1. The device for measuring the flowing speed of the liquid in the non-full pipe flow is characterized by comprising an excitation electrode (2) and a detection electrode (3) which are arranged on the outer wall of an insulating pipeline (1), wherein the excitation electrode (2) is connected with a signal generator (4) through a lead, and the detection electrode (3) is sequentially connected with a color ring inductor (5), a signal processing circuit (6), a data acquisition card (7) and a computer (8) through leads.
2. The non-full pipe flow liquid flow speed measuring device according to claim 1, wherein the signal processing circuit (6) comprises a flow voltage conversion circuit (6-1), a full-wave rectification circuit (6-2) and a low-pass filter circuit (6-3) which are connected in sequence through conducting wires, and the color ring inductor (5) and the data acquisition card (7) are respectively connected with the flow voltage conversion circuit (6-1) and the low-pass filter circuit (6-3).
3. A method for measuring a liquid flow rate in a non-full pipe flow, comprising the steps of:
the signal generator (4) outputs an AC voltage with a certain frequency to be applied toAn alternating current path is formed by the excitation electrode (2), the detection electrode (3) and a conductive solution between the excitation electrode (2) and the detection electrode (3), an alternating current signal containing solution conductivity information is output on the detection electrode (3) and is connected with the chromatic circle inductor (5) in series, the inductive reactance of the inductor is utilized to offset the capacitive reactance of the coupling capacitor, the influence of the coupling capacitor is eliminated, then the alternating current signal passes through the current-voltage conversion circuit (6-1), the full-wave rectification circuit (6-2) and the low-pass filter circuit (6-3) and then outputs a direct current voltage signal convenient to collect, the direct current voltage signal is collected by the data collection card (7) and transmitted to the computer (8) for data processing, the computer (8) carries out trend removing item processing on the output voltage signal, eliminates the interference of a measuring environment and carries out Fourier transform on the processed voltage signal to obtain a frequency spectrogram thereof, acquisition of the frequency f of a signal by means of a spectrogramiAnd amplitude hiThen according to the frequency f of the signaliAnd amplitude hiAnd calculating the equivalent peak frequency, and calculating the flow rate of the liquid according to the mathematical expression of the liquid flow speed and the equivalent peak frequency.
4. A method of measuring a non-full pipe flow liquid flow rate according to claim 3, wherein the frequency of the output voltage of the signal generator (4) is a resonant frequency.
5. A method of measuring a non-full pipe flow liquid flow rate as claimed in claim 3 wherein said equivalent peak frequency is calculated according to the formula:
wherein: f. ofeIs the equivalent peak frequency, fiFor obtaining the frequency f of a signal by means of a spectrogrami，hiIs a frequency fiThe corresponding amplitude, i, is the number of points in the spectral analysis.
6. A method as claimed in claim 5, wherein said mathematical expression of liquid flow rate and equivalent peak frequency is calculated as follows:
v＝kfe (2)
wherein k is a dimensionless correction coefficient in velocity measurement, and is calibrated by experiments, and v is the liquid flow velocity.
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| CN202111115602.8A CN113933534A (en) | 2021-09-23 | 2021-09-23 | Device and method for measuring liquid flowing speed of non-full pipe flow |
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| CN202111115602.8A CN113933534A (en) | 2021-09-23 | 2021-09-23 | Device and method for measuring liquid flowing speed of non-full pipe flow |
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Citations (8)
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|---|---|---|---|---|
| CN101387613A (en) * | 2008-10-17 | 2009-03-18 | 浙江大学 | Capacity coupling non-contact conductance measuring device based on series resonance and method |
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| CN106567708A (en) * | 2016-11-02 | 2017-04-19 | 浙江大学 | While-drilling lateral resistivity well test system based on C4D technology and signal detection method of while-drilling lateral resistivity well test system |
| CN110579622A (en) * | 2019-08-22 | 2019-12-17 | 西安理工大学 | Metal particle flow velocity measuring device and method based on triangular electrode capacitance sensor |
| CN111398102A (en) * | 2020-03-31 | 2020-07-10 | 西安理工大学 | Method for measuring average speed of solid particles of gas-solid two-phase flow in pipeline |
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2021
- 2021-09-23 CN CN202111115602.8A patent/CN113933534A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101387613A (en) * | 2008-10-17 | 2009-03-18 | 浙江大学 | Capacity coupling non-contact conductance measuring device based on series resonance and method |
| CN201269859Y (en) * | 2008-10-17 | 2009-07-08 | 浙江大学 | Measurement device for capacitor coupling type non-contact conductor based on series resonance |
| CN102269726A (en) * | 2011-05-10 | 2011-12-07 | 浙江大学 | Industrial capacitively coupled contactless conductivity online measurement device and method |
| CN102323442A (en) * | 2011-09-07 | 2012-01-18 | 浙江大学 | Fluid flow rate and flow measurement device and method |
| CN102645553A (en) * | 2012-05-16 | 2012-08-22 | 浙江大学 | Fluid flow speed and flow measuring device and method |
| CN106567708A (en) * | 2016-11-02 | 2017-04-19 | 浙江大学 | While-drilling lateral resistivity well test system based on C4D technology and signal detection method of while-drilling lateral resistivity well test system |
| CN110579622A (en) * | 2019-08-22 | 2019-12-17 | 西安理工大学 | Metal particle flow velocity measuring device and method based on triangular electrode capacitance sensor |
| CN111398102A (en) * | 2020-03-31 | 2020-07-10 | 西安理工大学 | Method for measuring average speed of solid particles of gas-solid two-phase flow in pipeline |
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