CN111610229B - Gas-liquid two-phase flow monitoring device, system and method - Google Patents
Gas-liquid two-phase flow monitoring device, system and method Download PDFInfo
- Publication number
- CN111610229B CN111610229B CN202010451803.4A CN202010451803A CN111610229B CN 111610229 B CN111610229 B CN 111610229B CN 202010451803 A CN202010451803 A CN 202010451803A CN 111610229 B CN111610229 B CN 111610229B
- Authority
- CN
- China
- Prior art keywords
- circuit
- capacitor
- resistor
- voltage
- electrically connected
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 239000007788 liquid Substances 0.000 title claims abstract description 79
- 238000000034 method Methods 0.000 title claims abstract description 70
- 230000005514 two-phase flow Effects 0.000 title claims abstract description 52
- 238000012806 monitoring device Methods 0.000 title claims abstract description 16
- 238000005259 measurement Methods 0.000 claims abstract description 76
- 230000005284 excitation Effects 0.000 claims abstract description 62
- 238000006243 chemical reaction Methods 0.000 claims abstract description 31
- 239000003990 capacitor Substances 0.000 claims description 88
- 238000003384 imaging method Methods 0.000 claims description 42
- 238000004891 communication Methods 0.000 claims description 29
- 238000012545 processing Methods 0.000 claims description 29
- 238000012544 monitoring process Methods 0.000 claims description 18
- 239000011159 matrix material Substances 0.000 claims description 16
- 238000004422 calculation algorithm Methods 0.000 claims description 15
- 230000003321 amplification Effects 0.000 claims description 14
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 14
- 238000001914 filtration Methods 0.000 claims description 10
- 230000004044 response Effects 0.000 claims description 8
- 230000033228 biological regulation Effects 0.000 claims description 6
- 125000004122 cyclic group Chemical group 0.000 claims description 6
- 238000007405 data analysis Methods 0.000 claims description 6
- 238000013500 data storage Methods 0.000 claims description 6
- 230000001105 regulatory effect Effects 0.000 claims description 6
- 230000006870 function Effects 0.000 description 35
- 239000012071 phase Substances 0.000 description 35
- 239000007789 gas Substances 0.000 description 30
- 238000010586 diagram Methods 0.000 description 14
- 230000008569 process Effects 0.000 description 13
- 238000012360 testing method Methods 0.000 description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- 230000000694 effects Effects 0.000 description 10
- 238000002474 experimental method Methods 0.000 description 8
- 238000000691 measurement method Methods 0.000 description 7
- 230000003068 static effect Effects 0.000 description 7
- 230000008859 change Effects 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 6
- 230000008901 benefit Effects 0.000 description 5
- 230000003993 interaction Effects 0.000 description 5
- 239000007791 liquid phase Substances 0.000 description 5
- 230000002093 peripheral effect Effects 0.000 description 5
- 238000004364 calculation method Methods 0.000 description 4
- 239000008367 deionised water Substances 0.000 description 4
- 229910021641 deionized water Inorganic materials 0.000 description 4
- 230000003287 optical effect Effects 0.000 description 4
- 238000013461 design Methods 0.000 description 3
- 238000010291 electrical method Methods 0.000 description 3
- 238000009499 grossing Methods 0.000 description 3
- 230000005855 radiation Effects 0.000 description 3
- 238000005070 sampling Methods 0.000 description 3
- 230000000007 visual effect Effects 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 238000000917 particle-image velocimetry Methods 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 239000000523 sample Substances 0.000 description 2
- 238000010183 spectrum analysis Methods 0.000 description 2
- 238000003325 tomography Methods 0.000 description 2
- 239000011800 void material Substances 0.000 description 2
- 230000003044 adaptive effect Effects 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 238000013528 artificial neural network Methods 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000003750 conditioning effect Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000010191 image analysis Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000010365 information processing Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000001483 mobilizing effect Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000003909 pattern recognition Methods 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 238000013112 stability test Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000008399 tap water Chemical group 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/06—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a liquid
- G01N27/08—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a liquid which is flowing continuously
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Abstract
The invention discloses a gas-liquid two-phase flow monitoring device, a system and a method, comprising a main control module, an excitation module, a silk screen sensor and a receiving module; the silk screen sensor is respectively and electrically connected with the excitation module and the receiving module; the excitation module comprises a polarity conversion circuit, a gating circuit and an amplifying circuit, and the polarity conversion circuit and the gating circuit are respectively and electrically connected with the main control module; the gating circuit is also electrically connected with the polarity conversion circuit and the amplifying circuit respectively; the receiving module comprises a transimpedance amplifying circuit, a first digital potentiometer circuit, a voltage amplifying circuit, a second digital potentiometer circuit and a signal acquisition circuit; the first digital potentiometer circuit is electrically connected with the transimpedance amplifying circuit and the main control module respectively; the voltage amplifying circuit is electrically connected with the transimpedance amplifying circuit; the second digital potentiometer circuit is electrically connected with the voltage amplifying circuit and the main control module respectively; the signal acquisition circuit is respectively and electrically connected with the voltage amplifying circuit and the main control module. The invention can realize the rapid and accurate measurement of the gas-liquid two-phase flow.
Description
Technical Field
The invention belongs to the technical field of gas-liquid two-phase flow monitoring, and particularly relates to a gas-liquid two-phase flow monitoring device, a gas-liquid two-phase flow monitoring system and a gas-liquid two-phase flow monitoring method.
Background
The measurement of parameters such as flow rate, flow pattern, pressure and phase content of the gas-liquid two-phase flow can be generally summarized in the following three categories:
(1) direct measurement technique
The direct measurement technique is mainly used for measuring specific two-phase flow parameters including flow pattern, flow velocity, gas content and the like. In the measurement of the gas content, the traditional method is to use a quick-closing valve method, the quick-closing valve method can seriously disturb a flow field, and the control requirement on a threshold valve is high. With the continuous development of technological progress, more and more new measuring methods are applied to the measurement of flow parameters of gas-liquid two-phase flow, such as an electrical method, a ray method, an optical method and the like.
The optical method mainly uses the principles of scattering, attenuation and the like when light passes through two-phase fluid to measure. And acquiring the change condition of light by utilizing the light sensor, and measuring the related parameters of the gas-liquid two-phase flow according to the output signal of the sensor. The method can measure parameters such as the size, the speed and the like of bubbles in the gas-liquid two-phase flow. The optical method is typical non-contact measurement, but has the problems of high cost of a data acquisition system and high requirement on measurement environment, and is difficult to apply and popularize industrially.
The radiation method mainly uses the principle that radiation is attenuated or compton scattered after passing through a medium to carry out measurement. Because different mediums have different attenuation or scattering conditions on the rays, the distribution information of the measured medium can be obtained by detecting the change of the radiation intensity of the rays after the rays pass through the measured medium, and then the flow pattern is determined. The ray method is non-contact measurement, but the protection cost is high when the ray method is used.
The electrical method is a method with wide application and mature technology. According to the principle of obvious difference of gas-liquid two-phase flow conductivity or dielectric constant, a sensor is adopted to convert the non-electrical measured information change into an electric signal change, and the measured information is obtained by collecting the electric signal. According to the principle, it can be classified into two types, namely, a conductivity measurement method and a capacitance measurement method. For example, based on a capacitance type cavitation device, the bubble velocity can be measured, and the method is mainly used for measuring micro channels, and based on a probe of a conductivity method, the related parameters such as local air content, bubble size, interface concentration, bubble apparent velocity and the like can be measured. Because of simple structure, low cost and good response characteristics, the electrical method plays an important role in the field of two-phase flow detection.
(2) Indirect measurement technique (Soft measurement)
The indirect measurement technology is to apply various modern information processing technologies to the field of gas-liquid two-phase flow, establish the relation between the easily-measured process variable and the process variable to be measured, and indirectly realize the measurement of the process variable to be measured through various theoretical calculation and estimation methods. The method is based on simple measurement parameters to realize the estimation of difficult measurement, and can be used for solving the problem of nonlinear complex two-phase flow system parameter measurement. In the multiphase flow measurement field, the common processing methods mainly comprise methods such as neural network, pattern recognition, spectrum analysis, wavelet analysis, spectrum analysis, soft measurement of fuzzy control and the like. The method is often used in a crossing and merging mode, and is mainly used for parameter measurement and two-phase flow mechanism research.
(3) Visual measurement technique
The visual measurement technology is to perform two-dimensional or three-dimensional imaging measurement on the gas-liquid two-phase flow, and can extract characteristic parameters from measurement results. Mainly comprises a particle image velocimetry, a high-speed camera shooting method, a process tomography method (Process Tomography, PT) and the like.
Particle image velocimetry is a measurement method based on flow field display and image analysis technology and is mainly used for measuring a fluid velocity field. The method has low picture definition due to uneven distribution of trace particles, noise of a camera, noise of an optical noise and other image noise, growth, aggregation, breakage and other phenomena of bubbles in the flowing process.
The high-speed photography method utilizes a high-speed camera to quickly photograph to obtain an image, and utilizes an image processing algorithm to extract gas-liquid two-phase flow information in the image. The method can only be used for measuring in a transparent pipeline, and in addition, the information quantity of the image acquired by high-speed shooting is too much, so that the analysis and the processing of the image are difficult.
Therefore, there is a need to develop a new gas-liquid two-phase flow monitoring device, system and method.
Disclosure of Invention
The invention aims to provide a gas-liquid two-phase flow monitoring device, a system and a method, which can realize rapid and accurate measurement of gas-liquid two-phase flow.
In a first aspect, the gas-liquid two-phase flow monitoring device comprises a main control module, an excitation module, a silk screen sensor, a receiving module, a communication module and a power module; the main control module is respectively and electrically connected with the excitation module, the receiving module, the communication module and the power supply module; the silk screen sensor is respectively and electrically connected with the excitation module and the receiving module;
the excitation module includes:
the polarity conversion circuit is used for converting the unipolar square wave signals generated by the main control module into bipolar square wave excitation signals and is electrically connected with the main control module;
the gating circuit is used for realizing continuous sequential multiplexing of bipolar square wave excitation signals and is respectively and electrically connected with the main control module and the polarity conversion circuit;
the amplifying circuit is used for amplifying signals output by the gating circuit and is electrically connected with the gating circuit and the excitation end of the silk screen sensor respectively;
the receiving module includes:
the transimpedance amplifying circuit is used for converting a received current signal into a voltage signal and is electrically connected with the output end of the silk screen sensor;
the first digital potentiometer circuit is used for adjusting the gain of the transimpedance amplifying circuit and is electrically connected with the transimpedance amplifying circuit and the main control module respectively;
The voltage amplifying circuit is used for amplifying the voltage signal output by the transimpedance amplifying circuit and is electrically connected with the transimpedance amplifying circuit;
the second digital potentiometer circuit is used for adjusting the gain of the voltage amplifying circuit and is electrically connected with the voltage amplifying circuit and the main control module respectively;
and the signal acquisition circuit is used for acquiring the voltage signal amplified by the voltage amplification circuit and is respectively and electrically connected with the voltage amplification circuit and the main control module.
Furthermore, the master control module adopts an STM32 minimum system, the STM32 minimum system is connected with an input port of the excitation module through an IO pin with a timer function, a timer register is configured to realize square wave signal output, and the excitation module is driven;
the STM32 minimum system is respectively and electrically connected with the first digital potentiometer circuit and the second digital potentiometer circuit through an SPI interface, the gain multiple of the transimpedance amplifying circuit is regulated and controlled through the resistance value regulation of the first digital potentiometer circuit, and the gain multiple of the voltage amplifying circuit is regulated and controlled through the resistance value regulation of the second digital potentiometer circuit;
The STM32 minimum system is electrically connected with the signal acquisition circuit through the FSMC interface, so that the efficient acquisition of multi-channel data is realized;
the STM32 minimum system is electrically connected with the communication module through the RMII interface, and achieves the network communication function of the embedded end and the computer end.
Further, the polarity conversion circuit comprises a capacitor C32, a capacitor C35 and a resistor R12, one end of the capacitor C32 is electrically connected with the main control module, the other end of the capacitor C32 is grounded after passing through the resistor R12, and a connection point of the capacitor C32 and the resistor R12 is grounded through the capacitor C35.
Further, the gating circuit comprises an analog switch U7, a resistor R4 to a resistor R11, a capacitor C7, a capacitor C9 and a capacitor C22 to a capacitor C29;
the analog switch U7 adopts a MAX4581CEE+ chip, and the 7 pin of the analog switch U7 is grounded after passing through a capacitor C9; the 16 pins of the analog switch U7 are grounded after passing through the capacitor C7; the 13 pin of the analog switch U7 is grounded after passing through the resistor R4, and the capacitor C22 is connected with the resistor R4 in parallel; the 14 pin of the analog switch U7 is grounded after passing through the resistor R5, and the capacitor C23 is connected with the resistor R5 in parallel; the 15 pin of the analog switch U7 is grounded after passing through the resistor R6, and the capacitor C24 is connected with the resistor R6 in parallel; the 12 pin of the analog switch U7 is grounded after passing through the resistor R7, and the capacitor C25 is connected with the resistor R7 in parallel; the 1 pin of the analog switch U7 is grounded after passing through a resistor R8, and a capacitor C26 is connected with the resistor R8 in parallel; the 5 pin of the analog switch U7 is grounded after passing through a resistor R9, and a capacitor C27 is connected with the resistor R9 in parallel; the 2 pin of the analog switch U7 is grounded after passing through the resistor R10, and the capacitor C28 is connected with the resistor R10 in parallel; the 4 pin of the analog switch U7 is grounded after passing through the resistor R11, and the capacitor C29 is connected with the resistor R11 in parallel;
The 3 pin of the analog switch U7 is electrically connected with the polarity conversion circuit;
and pins 12 to 15 of the analog switch U7 are also respectively and electrically connected with the amplifying circuit.
In a second aspect, the gas-liquid two-phase flow monitoring system of the invention comprises a computer end and a gas-liquid two-phase flow monitoring device;
the excitation module of the gas-liquid two-phase flow monitoring device adopts a cyclic scanning strategy, and each time sequentially transmits bipolar voltage excitation signals to one electrode wire at the excitation end of the wire mesh sensor, all response signals at the receiving end are subjected to current-to-voltage conversion, voltage amplification and AD conversion treatment, so that data acquisition of one electrode wire in the wire mesh sensor is completed; then exciting, receiving, processing again, and so on until the excitation of all electrode wires in the wire mesh sensor is completed, thereby obtaining a voltage matrix capable of reflecting the two-dimensional distribution of the conductivity at the section of the tested flow channel, obtaining phase state information of a complete section point, and transmitting the phase state information to a computer end in real time through a communication module;
the computer terminal is configured to: and carrying out data analysis, data storage and section data imaging processing on the received phase state information of each complete section point, displaying the two-phase distribution characteristics of the section of the flow field, and calculating and displaying the section air content.
Further, in the section data imaging processing, the intersection point of the screen sensor is taken as a pixel point, the measured value is taken as a corresponding pixel value, the pixel point of the image is increased by adopting an interpolation algorithm, and the image is filtered by adopting median filtering.
Further, a cubic spline interpolation method is adopted to increase the pixel points of the image.
Further, the method for calculating the section air content is as follows:
converting the voltage value matrix into a gas phase gas content matrix:
where ε (i, j, k) represents the local air content of the kth frame data at coordinates (i, j), u gas (i, j) represents a calibration voltage value when all the measurement points with coordinates (i, j) are gas flowing through, u liquid (i, j) represents a calibration voltage value when all the measurement points with coordinates (i, j) are liquid flowing through, and u (i, j, k) represents a voltage value of the measurement point with coordinates (i, j) in the kth frame data;
calculating the section air content:
wherein ,
is the section air content; a, a i,j A weight value corresponding to a measured value of a measuring point with coordinates (i, j);
wherein ,Asensor Representing the total area of a circular cross section, A i,j Representing epsilon i,j Corresponding effective area.
Further, the computer side is configured to: for viewing historical data, including tabular displays and view displays; the front view and the side view in the view reconstruct view information of the measuring pipeline by adopting a data projection method; front and side views are used to show the position of the bubble relative to the tube wall.
In a third aspect, the gas-liquid two-phase flow monitoring method according to the present invention adopts the gas-liquid two-phase flow monitoring system according to the present invention, and the method comprises the following steps:
and 3, the computer end performs data analysis, data storage and section data imaging processing on the received phase state information of each complete section point, displays the two-phase distribution characteristics of the section of the flow field, and calculates and displays the section air content.
The invention has the following advantages: the silk screen sensor imaging technology has the advantages of simple principle, low research and development cost, high imaging speed, multiple measurable parameters, uniform spatial resolution and the like. The gas-liquid two-phase flow monitoring system based on the silk screen sensor can realize rapid and accurate measurement of the gas-liquid two-phase flow and has the characteristics of wide dynamic measurement range, low cost and small volume. The gas-liquid two-phase flow monitoring based on the silk screen sensor belongs to contact type measurement, so that compared with indirect measurement, the device has the advantages of simple equipment, low cost and strong anti-interference capability, but compared with traditional contact type measurement, the novel measurement mode has the advantages of small contact area, small interference on a flow field, suitability for various occasions such as laboratories and industries, and wider application. The invention can accurately measure the conductivity less than or equal to 0.1 mu S/cm due to the self-adaptive realization.
Drawings
FIG. 1 is a schematic block diagram of the present embodiment;
fig. 2 is a circuit diagram of a master control module in the present embodiment;
FIG. 3 is a circuit diagram of the polarity inversion circuit in the present embodiment;
fig. 4 is a circuit diagram of a select-through circuit in the present embodiment;
fig. 5 is a circuit diagram of an amplifying circuit in the present embodiment;
FIG. 6 is a circuit diagram of the transimpedance amplifier circuit and the first digital potentiometer circuit in the present embodiment;
FIG. 7 is a circuit diagram of the voltage amplifying circuit and the second digital potentiometer circuit in the present embodiment;
FIG. 8 is a circuit diagram of the signal acquisition circuit in the present embodiment;
fig. 9 is a circuit diagram of the communication module in the present embodiment;
FIG. 10 is a diagram showing the configuration of the device-side software and the computer-side software according to the present embodiment;
FIG. 11 is a flow chart showing the reconstruction image display in the present embodiment;
FIG. 12 is a schematic view of the measured value region in the present embodiment;
FIG. 13 is a flow chart showing the cross-sectional air content in the present embodiment;
FIG. 14 is a schematic view of data projection of a frame in the present embodiment;
FIG. 15 is a diagram showing the imaging effect of static measurement in the present embodiment;
FIG. 16 shows the cross-sectional imaging effect at different bubble sizes in this embodiment;
in the figure: 1. the device comprises a main control module, 2, an excitation module, 2a, a polarity conversion circuit, 2b, a gating circuit, 2c, an amplifying circuit, 3, a silk screen sensor, 4, a receiving module, 4a, a transimpedance amplifying circuit, 4b, a first digital potentiometer circuit, 4c, a voltage amplifying circuit, 4d, a second digital potentiometer circuit, 4e, a signal acquisition circuit, 5, a power module, 6, a communication module, 7 and a computer end.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
As shown in fig. 1, a gas-liquid two-phase flow monitoring device comprises a main control module 1, an excitation module 2, a silk screen sensor 3, a receiving module 4, a communication module 6 and a power supply module 5; the main control module 1 is respectively and electrically connected with the excitation module 2, the receiving module 4, the communication module 6 and the power supply module 5; the screen sensor 3 is electrically connected to the excitation module 2 and the receiving module 4, respectively.
As shown in fig. 1, in this embodiment, the excitation module 2 mainly realizes sequential control of bipolar voltage excitation signals with stable multi-channel amplitude, so as to complete sequential excitation of the screen sensor 3. The excitation module 2 includes a polarity inversion circuit 2a, a gate circuit 2b, and an amplification circuit 2c. The polarity conversion circuit 2a is composed of a high-pass filter circuit, and is configured to convert a unipolar square wave signal generated by the main control module 1 into a bipolar square wave excitation signal, where the polarity conversion circuit 2a is electrically connected with the main control module 1. The gating circuit 2b is composed of multiplexing analog switches and is used for realizing continuous sequential multiplexing of bipolar square wave excitation signals, and the gating circuit 2b is respectively and electrically connected with the main control module 1 and the polarity conversion circuit 2 a. The amplifying circuit 2c is mainly composed of amplifying chips with constant gain, and is used for amplifying signals output by the gating circuit 2b, enhancing the driving capability of the excitation signals and reducing the influence of loads, and the amplifying circuit 2c is electrically connected with the gating circuit 2b and the excitation end of the screen sensor 3 respectively.
In this embodiment, a bipolar square wave voltage signal is selected to excite the emitter electrode. The common voltage excitation is a direct current signal, a bipolar sine wave signal or a bipolar square wave signal. If the emitter electrode is activated by a direct voltage, polarization of the dielectric electrode will occur, thereby introducing errors in the conductivity measurement. In addition, if the transmitting electrodes are activated by alternating sine wave voltage signals, the circuit will require a complex and time consuming demodulation process, thereby reducing the speed of system data acquisition. The bipolar square wave voltage signal can protect the electrodes from polarization due to the same amplitude and opposite polarity of the two adjacent half-cycles. In the half period of measurement, the transmitting electrode can be regarded as being excited by a constant direct-current voltage signal, and the receiving electrode does not need to undergo more complex signal conditioning processes such as amplification, filtering, rectification and the like, so that a bipolar voltage excitation signal is selected to drive the excitation module.
In this embodiment, as shown in fig. 1, the receiving module 4 is mainly configured to implement quantized collection of multiple weak current response signals; the receiving module 4 comprises a transimpedance amplifying circuit 4a, a first digital potentiometer circuit 4b, a voltage amplifying circuit 4c, a second digital potentiometer circuit 4d and a signal acquisition circuit 4e. The transimpedance amplifier circuit 4a is used for converting a received current signal into a voltage signal, and the transimpedance amplifier circuit 4a is electrically connected with the output end of the screen sensor 3. The first digital potentiometer circuit 4b is used for adjusting the gain of the transimpedance amplifying circuit 4a, and the first digital potentiometer circuit 4b is electrically connected with the transimpedance amplifying circuit 4a and the main control module 1 respectively. The voltage amplifying circuit 4c is configured to amplify the voltage signal output from the transimpedance amplifying circuit 4a, and the voltage amplifying circuit 4c is electrically connected to the transimpedance amplifying circuit 4 a. The second digital potentiometer circuit 4d is used for adjusting the gain of the voltage amplifying circuit 4c, and the second digital potentiometer circuit 4d is electrically connected with the voltage amplifying circuit 4c and the main control module 1 respectively. The signal acquisition circuit 4e is used for acquiring the voltage signal amplified by the voltage amplification circuit 4c, and the signal acquisition circuit 4e is electrically connected with the voltage amplification circuit 4c and the main control module 1 respectively.
In this embodiment, the gain control of the amplifying circuit is realized by changing the magnitude of the feedback resistor by using a digital potentiometer. The transimpedance amplifying circuit can avoid integral errors caused by input offset voltage, input bias current and offset current of the operational amplifier, errors caused by capacitance leakage current, measurement errors of nanoscale conductivity and measurement accuracy are effectively improved.
In this embodiment, as shown in fig. 2, the master control module 1 adopts an STM32 minimum system, where the STM32 minimum system is connected to an input port of the excitation module 2 through an IO pin with a timer function, and configures a timer register to implement square wave signal output, so as to drive the excitation module 2. The STM32 minimum system is respectively and electrically connected with the first digital potentiometer circuit 4b and the second digital potentiometer circuit 4d through SPI interfaces, the gain multiple of the mutual resistance amplifying circuit 4a is regulated and controlled through the resistance value regulation of the first digital potentiometer circuit 4b, and the gain multiple of the voltage amplifying circuit 4c is regulated and controlled through the resistance value regulation of the second digital potentiometer circuit 4 d. The STM32 minimum system is electrically connected with the signal acquisition circuit 4e through the FSMC interface, so that efficient acquisition of multi-channel data is realized. The STM32 minimum system is electrically connected with the communication module 6 through an RMII interface, so that the network communication function between the embedded end (i.e. the device end) and the computer end is realized.
In this embodiment, as shown in fig. 3, the polarity conversion circuit 2a includes a capacitor C32, a capacitor C35 and a resistor R12, one end of the capacitor C32 is electrically connected to the main control module 1, the other end of the capacitor C32 is grounded through the resistor R12, and the connection point between the capacitor C32 and the resistor R12 is also grounded through the capacitor C35.
As shown in fig. 4, in the present embodiment, the gating circuit 2b includes an analog switch U7, a resistor R4 to a resistor R11, a capacitor C7, a capacitor C9, and a capacitor C22 to a capacitor C29. The analog switch U7 adopts a MAX4581CEE+ chip, and the 7 pin of the analog switch U7 is grounded after passing through a capacitor C9. The 16 pins of the analog switch U7 are grounded through a capacitor C7. The 13 pin of the analog switch U7 is grounded after passing through the resistor R4, and the capacitor C22 is connected with the resistor R4 in parallel. The 14 pin of the analog switch U7 is grounded after passing through the resistor R5, and the capacitor C23 is connected with the resistor R5 in parallel. The 15 pin of the analog switch U7 is grounded after passing through the resistor R6, and the capacitor C24 is connected with the resistor R6 in parallel. The 12 pin of the analog switch U7 is grounded after passing through the resistor R7, and the capacitor C25 is connected with the resistor R7 in parallel. The 1 pin of the analog switch U7 is grounded after passing through the resistor R8, and the capacitor C26 is connected with the resistor R8 in parallel. The 5 pin of the analog switch U7 is grounded after passing through the resistor R9, and the capacitor C27 is connected with the resistor R9 in parallel. The 2 pin of the analog switch U7 is grounded after passing through the resistor R10, and the capacitor C28 is connected with the resistor R10 in parallel. The 4 pins of the analog switch U7 are grounded after passing through the resistor R11, and the capacitor C29 is connected with the resistor R11 in parallel. The 3 pin of the analog switch U7 is electrically connected to the polarity conversion circuit 2 a. The pins 12 to 15 of the analog switch U7 are also electrically connected to the amplifying circuit 2c, respectively.
As shown in fig. 5, in the present embodiment, the amplifying circuit 2C includes an amplifier U2, a capacitor C1, and a capacitor C5. The amplifier U2 adopts a max4022eee chip, the 4 pin of the amplifier U2 is grounded after passing through the capacitor C1, and the 13 pin of the amplifier U2 is grounded after passing through the capacitor C5. The 3 pin, the 4 pin, the 12 pin and the 14 pin of the amplifier U2 are electrically connected to the gate circuit 2b, respectively.
As shown in fig. 6, the transimpedance amplifier circuit 4a includes an operational amplifier U21, a capacitor C108, a capacitor C120, a capacitor C124, and a capacitor C128. The operational amplifier U21 adopts an OPA4132UA chip, one end of the capacitor C108 is connected with the 1 pin of the operational amplifier U21, and the other end of the capacitor C108 is connected with the 2 pin of the operational amplifier U21. One end of the capacitor C120 is connected to the 6 pin of the operational amplifier U21, and the other end of the capacitor C120 is connected to the 7 pin of the operational amplifier U21. One end of the capacitor C124 is connected to the 9 pin of the operational amplifier U21, and the other end of the capacitor C124 is connected to the 8 pin of the operational amplifier U21. One end of the capacitor C128 is connected to the 13 pin of the operational amplifier U21, and the other end of the capacitor C128 is connected to the 14 pin of the operational amplifier U21.
As shown in fig. 7, the voltage amplifying circuit 4C includes an operational amplifier U22 and peripheral circuits including a capacitor C109, a capacitor C121, a capacitor C125, a capacitor C129, a resistor R32, a resistor R34, a resistor R36, a resistor R38, a resistor R40, a resistor R45, a resistor R46, and the like. Wherein, the operational amplifier U22 adopts an OPA4820IPWT chip, one end of a capacitor C109 is connected with the 1 pin of the operational amplifier U22, and the other end of the capacitor C109 is connected with the 2 pin of the operational amplifier U22. One end of the capacitor C121 is connected to the 6 pin of the operational amplifier U22, and the other end of the capacitor C121 is connected to the 7 pin of the operational amplifier U22. One end of the capacitor C125 is connected to the 9 pin of the operational amplifier U22, and the other end of the capacitor C125 is connected to the 8 pin of the operational amplifier U22. One end of the capacitor C129 is connected to the 13 pin of the operational amplifier U22, and the other end of the capacitor C129 is connected to the 14 pin of the operational amplifier U22.
As shown in fig. 6, in the present embodiment, the first digital potentiometer circuit 4b includes a digital potentiometer U19 and a peripheral circuit, and the model of the digital potentiometer U19 is AD5263BRZ200.
As shown in fig. 7, in the embodiment, the second digital potentiometer circuit 4d includes a digital potentiometer U20 and a peripheral circuit, and the model of the digital potentiometer U20 is AD5263BRZ200.
As shown in fig. 8, in the present embodiment, the signal acquisition circuit 4e includes an analog-to-digital converter U4 and a peripheral circuit, and the model of the analog-to-digital converter U4 is AD7606BSTZ.
As shown in fig. 9, in the present embodiment, the communication module 6 is mainly composed of a network communication circuit, and the communication module 6 includes a PHY chip and a peripheral circuit, and the model of the PHY chip is DP838481VV.
In this embodiment, the power module 5 is composed of a voltage stabilizing circuit, and mainly provides different power supply voltages for the inside of the system.
In this embodiment, a gas-liquid two-phase flow monitoring system includes a computer terminal and a gas-liquid two-phase flow monitoring device as described in this embodiment.
The excitation module of the gas-liquid two-phase flow monitoring device adopts a cyclic scanning strategy, and each time sequentially transmits bipolar voltage excitation signals to one electrode wire at the excitation end of the wire mesh sensor, all response signals at the receiving end are subjected to current-to-voltage conversion, voltage amplification and AD conversion treatment, so that data acquisition of one electrode wire in the wire mesh sensor is completed; and then exciting, receiving, processing and the like again until the excitation of all electrode wires in the wire mesh sensor is completed, thereby obtaining a voltage matrix capable of reflecting the two-dimensional distribution of the conductivity at the section of the tested flow channel, obtaining phase state information of a complete section point, and transmitting the phase state information to a computer end in real time through a communication module.
The computer terminal is configured to: and carrying out data analysis, data storage and section data imaging processing on the received phase state information of each complete section point, displaying the two-phase distribution characteristics of the section of the flow field, and calculating and displaying the section air content.
In this embodiment, in order to facilitate the user to control the device and view information such as measurement data, a piece of software is developed as system parameter setting and imaging display, and the gating UDP protocol realizes rapid interaction between the gas-liquid two-phase flow monitoring device and the computer.
As shown in fig. 10, software at the device end mainly completes quantitative acquisition of voltage signals of each measuring point in the measured area and rapid transmission of result data. In order to realize the functions, the functions of analog switch control, signal acquisition and processing, digital potentiometer control, parameter storage, network communication and the like are required to be realized on the embedded platform.
(1) Analog switch control: the binary weighting mode is adopted to control the ordered switching of the analog switch, so that the time division multiplexing of the excitation signals is realized.
(2) And (3) signal acquisition and processing: and the rapid quantitative acquisition of the voltage signals of each measuring point in the measured area is realized by adopting an STM32 minimum system driving acquisition chip mode.
(3) Digital potentiometer control: and sending a command to adjust the output resistance of the digital potentiometer (namely the first digital potentiometer circuit and the second digital potentiometer circuit) through the SPI bus, so as to realize the gain setting of the program-controlled amplifier (namely the transimpedance amplifying circuit and the voltage amplifying circuit) at the receiving end.
(4) And (3) parameter preservation: taking into account that the gain setting of the program controlled amplifier is required after each start of the system, the parameter saving function is required to be completed in order to reduce the repeated setting work of the user. The system automatically stores the latest operational amplifier gain information, and when the system is started next time, the operational amplifier gain setting is completed by reading the stored operational amplifier gain information.
(5) Network communication: in order to reduce the occupation of the memory by communication as much as possible, the embedded platform is considered to have limited memory capacity, the network communication function is realized by transplanting a lightweight LWIP protocol stack at the embedded end, and the quick uploading of the measurement data is realized by using a UDP mode.
As shown in FIG. 10, the software design of the computer end mainly completes the operations of converting the received voltage information of each measuring point, storing data, extracting the gas content parameter, reconstructing the section image and the like, and setting the system parameters and checking the historical data. In order to realize the functions, the software at the computer end is required to realize the functions of system parameter setting, section imaging display, gas content display, historical data display, network communication and the like.
(1) Cross-section imaging shows: in order for the user to more intuitively see the cross-sectional phase distribution at the screen sensor 3, 30 frames will be extracted from the measurement data per second for imaging display. And adding pixels of the image by using a corresponding interpolation algorithm, improving the resolution of the image, and smoothing the image by using a median filtering algorithm so as to optimize the display quality of the image.
(2) Section void fraction shows: in order to enable a user to more accurately grasp gas-liquid phase information of the section of the pipeline, section gas-containing rate parameters are extracted from measurement data, and the extracted parameters are displayed.
(3) And (3) data preservation: to facilitate viewing and secondary development of the measurement data, the system should have the functionality to save the measurement data in the form of a TXT document.
(4) And (3) setting system parameters: in order to better meet the measurement of the monitoring system on various gas-liquid two-phase flows, the system needs to have a system parameter setting function. According to different application scenes, two setting modes of self-defining parameters and self-adapting parameters are mainly provided, the self-defining parameter setting mode is mainly applied to gain debugging of a designated passage, and the self-adapting parameter setting mode is mainly applied to measurement of different gas-liquid two-phase flows. In order to improve the efficiency of parameter adjustment when the system measures different media, the embedded end designs an adaptive algorithm.
(5) Historical data display: in order to facilitate the user's viewing of the historical data, the system should have the function of displaying the historical data in a tabular and graphical manner. In the image display section, a data projection method is designed.
(6) Network communication function: in order to realize rapid data interaction between the computer end and the device end, software of the computer end is realized by Socket programming based on UDP protocol. Communication protocols have also been designed in view of the normative of interaction data.
In this embodiment, the intersection of the screen sensor is taken as a pixel point, the measured value is taken as a corresponding pixel value, and the phase distribution characteristic of the detected area can be reflected by directly performing imaging display. However, the total number of measurement points of the screen sensor is limited, and a certain distance exists between the measurement points, so that the resolution of direct imaging is not high. In order to optimize the image display quality, the pixels of the image need to be increased by using a corresponding interpolation algorithm to improve the resolution of the image. For image edge smoothing, median filtering is used to filter the image. Therefore, in this embodiment, the image reconstruction algorithm adopts a method of combining an interpolation algorithm with a median filtering algorithm. Currently, commonly used interpolation algorithms include nearest neighbor, bilinear interpolation, bicubic interpolation, cubic spline interpolation, and the like. In this embodiment, a cubic spline interpolation method is used to increase the pixels of the image.
In this embodiment, a screen sensor of 16×16 will be described as an example. The cubic spline interpolation method also considers the relation between the point to be interpolated and the 16 adjacent points around, and takes the relation into accountAnd adjusting S (w) on the basis of interpolation, wherein S (w) is a cubic spline curve and is a piecewise function. Let a=w 0 ＜w 1 ＜…＜w n-1 ＜w n =b, given node. If the function S (w) is in the definition domain [ a, b ]]Each inter-cell [ w ] i ,w i+1 ]The above is a cubic polynomial and satisfies S (w i )＝f i (remark: f) i Is a polynomial) and S (w), S ' (w) (S ' (w) is the derivative of S (w), S "(w) (S" (w) is the derivative of S ' (w)) are defined as [ a, b ]]Continuing above, then S (w) is called a cubic spline function, the function is expressed as formula (1):
S i (w)＝a i (w-w i ) 3 +b i (w-w i ) 2 +c i (w-w i )+d i
i＝0,1,2……,n-1,n (1)
wherein ,ai 、b i 、c i 、d i Is the corresponding coefficient of the corresponding interval polynomial.
The cubic spline interpolation method not only considers the correlation of pixel points in a larger neighborhood of the interpolation point, but also introduces the concept of spline curve to optimize the imaging effect, and the transition among pixels is smooth, so that the imaging quality is closer to the real situation.
The cubic spline interpolation method not only considers the correlation of adjacent pixel points of the periphery 16, but also introduces the concept of a curve to optimize the imaging effect, so that the imaging picture approximates to the real picture.
In order to make the image smoother and approach the real image, in this embodiment, a median filtering algorithm is used to smooth the image. The median filtering is a nonlinear smoothing filtering method, and the basic idea is to use a sliding window containing odd points, sort the gray values in the window, and then assign the values to the center point. The reconstruction method of the cross-section image of the system is to firstly conduct cubic spline interpolation processing on data and then conduct median filtering processing.
In this embodiment, the imaging display adopts a display scheme that white represents gas and blue represents liquid, and the shade of blue is determined by the size of the measured value, and the larger the measured value is, the deeper the blue is. The display function is mainly developed and realized by using a cv2 module, and cv2 is a C++ naming space name of opencv and is used for calling an interface of opencv developed by C++. The specific imaging display flow is as follows: firstly, a reshape () function is called to convert data into a gray image, then, a resize () function in a cv2 module is called to finish image scaling, then, a color space conversion function cvtColor () function and a channel splitting function split () function in the cv2 module are called to finish blue component extraction, and finally, a setPixmap () function in a QLabel is used to finish image display.
In this embodiment, the cross-sectional imaging display is divided into two displays of an original image and a reconstructed image. For the original image display, the interaction parameter of the restore () function in the above display flow is assigned to cv2.intersect_none. For reconstructed image display, the interaction parameter of the resize () function in the above display flow is assigned to cv2.Inter_cubic representing CUBIC spline interpolation, and the median filter processing is completed by mobilizing the medianbir () function in the cv2 module, and the reconstructed image display flow chart is shown in fig. 11. The imaging display requires thresholding of the measured data, and proper thresholding can better describe the gas-liquid two-phase distribution in the cross section of the pipeline. The thresholding and reconstruction image processing are described with a frame of measurement data, which is measured when liquid is continuously flowing from the middle of the screen by using a circular pipe of a suction pump, and theoretically, the liquid phase region in the imaged picture should be approximately circular.
In this embodiment, in order to enable a user to more accurately grasp the gas-liquid phase information of the section of the pipeline, the section gas-containing rate display function is realized. The cross section gas content refers to the ratio of the area occupied by the gas phase on a certain cross section of the pipeline to the total area of the cross section. In the actual calculation process, in order to avoid the influence of the processing error and the boundary effect of the screen sensor, the measured voltage value often needs to be checked to obtain the local conductivity distribution condition, thereby obtaining the local air content.
The most common calibration method is to calibrate the voltage values by measuring the two conditions of the pipeline completely filled with gas and liquid. The specific implementation process is that when the pipeline is filled with liquid, the conductivity is maximum, a unit value is designated, when the pipeline is filled with all gases, the conductivity is minimum, the value can be assigned to zero, and the voltage values of two points are recorded. The theoretical expression is shown as formula (2).
Where i, j denotes a coordinate position (grid point number of the screen), k denotes what frame data, ε (i, j, k) denotes a local air content of (i, j) in the kth frame data, c (i, j, k) denotes an electric conductivity of (i, j) in the kth frame data, c gas (i, j) represents the electrical conductivity (usually 0) of the gas filled tube, c liquid (i, j) represents the conductivity of the liquid filled tube. Since the measured voltage is linearly related to the conductivity, equation 2 is converted into equation 3.
wherein ,ugas (i, j) represents a calibration voltage value when all the measurement points with coordinates (i, j) are gas flowing through, u liquid (i, j) represents a calibration voltage value when all the measurement points with coordinates (i, j) are liquid flowing therethrough, and u (i, j, k) represents a voltage value of the measurement point with coordinates (i, j) in the kth frame data. The voltage value matrix can be converted into a gas phase gas content matrix by using the formula (3).
In this embodiment, a 16x16 wire mesh sensor is used, with 256 measurements per frame, since the sensor electrodes are distributed in a circular pipe cross section, 48 crossing points are located outside the cross section, and only 208 crossing points are valid measurements. When calculating the gas content parameters of the pipeline section, whether the measuring points are located in the central area or the boundary area needs to be considered, and different areas are given different weight values. The cross section void fraction can be calculated according to equation (4).
wherein ,ai,j The calculation of the weight value corresponding to the measured value of the measuring point with coordinates (i, j) is based on the calculation of a simple geometric area, and the formula is formula (5).
wherein ,Asensor Representing the total area of a circular cross section, A i,j Representing epsilon i,j Corresponding effective area. The area diagram of the measured value is shown in FIG. 12, the shaded portion in FIG. 12 represents the effective area of the measured value corresponding to the point A when the measured point is in the central area i,j =Δx·Δy, a when the measurement point is located in the boundary region i,j < Δx·Δy, since the spacing between adjacent electrode wires in the same layer in the sensor is 3mm, Δx=Δy=3 mm.
In this embodiment, the corresponding processing function is integrated into the background processing function of the computer software to calculate the air content of the section, so as to realize the air content display function. The implementation process is as follows: the method comprises the steps of firstly obtaining section phase state information data collected by an embedded end through a recvfrom () function, then analyzing the obtained data and extracting section gas content parameters, and finally updating the section gas content parameters to a UI. The cross section gas fraction display flow chart is shown in fig. 13.
In this embodiment, in order to facilitate the user to view and analyze the historical data, the software at the computer end realizes the function of displaying the historical data. Mainly, there are two functions of table and view display. Wherein, the front view and the side view in the view reconstruct the view information of the measuring pipeline by a data projection method. The front and side views only show the position of the bubble relative to the tube wall, and do not restore the size of the actual bubble, which may be stretched or collapsed in the picture.
In this embodiment, the data projection method is a method of projecting based on the row and column maximum of the measured values. For front projection, the column minimum of the measured values is selected for projection. The specific flow of the projection algorithm is as follows: firstly, reading a frame of data from a historical data file, converting the data into a 16×16 matrix, extracting the minimum value of effective measured values in each column to obtain a 16×1 matrix, then reading a frame of data, performing the same processing on the data, splicing the two projection results to obtain a 16×2 matrix, and then continuing the operation processes of reading, projecting, splicing and the like until the last frame of data. Taking the measurement data of the screen sensor of 8×8 measuring points as an example, a data projection diagram of one frame is shown in fig. 14, wherein "0" and "1" replace the measurement voltage values. The side view display principle is similar to the front view display principle, except that the data of the measurement value matrix is subjected to projection processing, and will not be described here.
In this embodiment, a gas-liquid two-phase flow monitoring method adopts the gas-liquid two-phase flow monitoring system as described in this embodiment, and the method includes the following steps:
and 3, the computer end performs data analysis, data storage and section data imaging processing on the received phase state information of each complete section point, displays the two-phase distribution characteristics of the section of the flow field, and calculates and displays the section air content.
Most of the current gas-liquid two-phase flow monitoring is based on 'soft field' measurement, uneven electric field distribution, complex image reconstruction algorithm and low imaging precision. The method for measuring the screen sensor based on the hard field is used for measuring the instantaneous phase distribution condition of the gas-liquid two-phase flow contact sensor, has the advantages of simple structure, simple image reconstruction algorithm, high imaging precision and the like, and has great significance for visual measurement of the gas-liquid two-phase flow. The requirements of the system sampling rate and the imaging precision, which are improved due to the continuous improvement of the requirements of the industrial field, can be met.
The following two performance indexes of the device, namely the acquisition speed and the stability, are tested:
(1) acquisition speed test
The acquisition speed test is a test for counting the data sent by the embedded terminal and obtaining the acquisition speed. The sample rate statistics are shown in table 1.
Table 1 the speed statistics are collected:
from the data in the table, the average sampling speed of the system is 625 frames/s, and the sampling speed reaches the expected requirement.
(2) Run stability test
The system can stably work under the test of 24 hours for many times, and in the continuous operation process, the acquisition, transmission, processing and storage of the phase state information of the cross section of the convection field can be normally finished according to the set system parameters.
System parameters:
in this embodiment, in order to verify the imaging effect experiment of the system, two measurement schemes of static measurement and dynamic measurement are formulated according to whether the phase distribution changes.
The static measurement refers to measurement that the screen sensor is positioned in a constant gas-liquid two-phase distribution environment. The height of the liquid is controlled to be just equal to that of the silk screen, the pipeline is inclined by 45 degrees, so that one half area of the silk screen sensor is immersed in water, and the other half area of the silk screen sensor is exposed in air, and a static gas-liquid two-phase distribution environment is formed.
The dynamic measurement refers to measurement of the screen sensor in a continuously-changing gas-liquid two-phase distribution environment, and is divided into two test experiments: under the experimental environment of injecting liquid into the silk screen by adopting a water suction pump circulation, performing image reconstruction by using measurement data when the liquid just contacts with a silk screen sensor; in another environment where a pump is used to continuously provide a flow of bubbles to the conduit, image reconstruction is performed using measurement data from the bubble just touching the wire mesh sensor. Before the experiment, a group of data measurement is completed in the liquid environment and the gas environment in the experimental section, and the data are used for correcting the measured values so as to avoid the boundary effect and the processing error of the screen sensor.
For static measurement, a static gas-liquid two-phase distribution environment is formed by adopting a method that an experimental section is inclined by 45 degrees along the direction of the electrode wire. And selecting different test liquids to perform experiments, wherein the experiment liquids comprise primary deionized water, secondary deionized water, tertiary deionized water and tap water. When the test liquid is primary deionized, a static measurement imaging effect diagram is shown in fig. 15, in which the blue part represents liquid and the white part represents gas. The experimental data are shown in table 2.
Table 2:
from the above test results, it can be seen that the system is capable of measuring liquids having conductivities in the range of 0.1-125 μS/cm; in a measurement laboratory, the boundary of the gas phase and the liquid phase in the imaging result is obvious, and the angle of the boundary is basically consistent with the inclination angle, so that the system can better distinguish the two phases of the gas phase and the liquid phase in the detection range, and the design requirement can be met.
For dynamic measurement, in experiments, liquid is injected into the silk screen sensor by using a water suction pump for circulation, the contact area of a water column on the silk screen sensor is changed by continuously moving the pipeline position and extruding the pipeline, and the contact area is compared with the shape and the position of the liquid in the computer-end software section imaging. Through testing, the position of the water column contacting the silk screen can be corresponding to the liquid position in the imaging picture in real time, and the shape of the blue image in the imaging picture changes along with the change of the shape of the water column.
From the test results, the cross-section imaging results can better reflect the real situation of the moment when the water column just contacts the wire mesh sensor. Single bubbles of different sizes are generated by the inflation pump, measurement data of the bubbles just contacting the sensor are extracted, and the data are used for reconstruction display. The system records a photo of the bubble before entering the screen sensor by using a camera, can measure the proportion of the bubble relative to the diameter of the pipeline by using a physical photo, is used for comparing the sizes of the bubble in the section imaging pictures, and verifies the imaging effect of the system measurement data. In the experiment, the test liquid was primary deionized water with a bubble velocity of no more than 0.5m/s at maximum. Through testing, the shape of the bubble in the imaging picture is similar to that of the bubble in the picture. The cross-sectional imaging effect at different bubble sizes is shown in fig. 16. In the figure, the blue part represents liquid, and the white part represents gas.
According to experiments, under the motion single-bubble experimental environment, the sectional imaging result can better reflect the instant real situation of the bubble contact sensor, the shape of the white area is similar to that of the real bubble, and the size of the white area changes along with the change of the bubble size, so that the system can meet the design requirement.
Claims (5)
1. A gas-liquid two-phase flow monitoring device is characterized in that: the device comprises a main control module (1), an excitation module (2), a silk screen sensor (3), a receiving module (4), a communication module (6) and a power supply module (5); the main control module (1) is electrically connected with the excitation module (2), the receiving module (4), the communication module (6) and the power supply module (5) respectively; the silk screen sensor (3) is respectively and electrically connected with the excitation module (2) and the receiving module (4);
the excitation module (2) comprises:
the polarity conversion circuit (2 a) is used for converting a unipolar square wave signal generated by the main control module (1) into a bipolar square wave excitation signal, and the polarity conversion circuit (2 a) is electrically connected with the main control module (1);
the gating circuit (2 b) is used for realizing continuous sequential multiplexing of bipolar square wave excitation signals, and the gating circuit (2 b) is respectively and electrically connected with the main control module (1) and the polarity conversion circuit (2 a);
the amplifying circuit (2 c) is used for amplifying the signal output by the gating circuit (2 b), and the amplifying circuit (2 c) is electrically connected with the exciting ends of the gating circuit (2 b) and the silk screen sensor (3) respectively;
the receiving module (4) comprises:
the transimpedance amplifying circuit (4 a) is used for converting a received current signal into a voltage signal, and the transimpedance amplifying circuit (4 a) is electrically connected with the output end of the silk screen sensor (3);
The first digital potentiometer circuit (4 b) is used for adjusting the gain of the transimpedance amplifying circuit (4 a), and the first digital potentiometer circuit (4 b) is electrically connected with the transimpedance amplifying circuit (4 a) and the main control module (1) respectively;
a voltage amplifying circuit (4 c) for amplifying the voltage signal outputted from the transimpedance amplifying circuit (4 a), the voltage amplifying circuit (4 c) being electrically connected to the transimpedance amplifying circuit (4 a);
the second digital potentiometer circuit (4 d) is used for adjusting the gain of the voltage amplifying circuit (4 c), and the second digital potentiometer circuit (4 d) is electrically connected with the voltage amplifying circuit (4 c) and the main control module (1) respectively;
the signal acquisition circuit (4 e) is used for acquiring the voltage signal amplified by the voltage amplification circuit (4 c), and the signal acquisition circuit (4 e) is electrically connected with the voltage amplification circuit (4 c) and the main control module (1) respectively;
the main control module (1) adopts an STM32 minimum system, the STM32 minimum system is connected with an input port of the excitation module (2) through an IO pin with a timer function, a timer register is configured to realize square wave signal output, and the excitation module (2) is driven;
the STM32 minimum system is electrically connected with the first digital potentiometer circuit (4 b) and the second digital potentiometer circuit (4 d) through SPI interfaces respectively, the gain multiple of the transimpedance amplifying circuit is regulated and controlled through the resistance value regulation of the first digital potentiometer circuit (4 b), and the gain multiple of the voltage amplifying circuit is regulated and controlled through the resistance value regulation of the second digital potentiometer circuit (4 d);
The STM32 minimum system is electrically connected with the signal acquisition circuit (4 e) through an FSMC interface, so that the efficient acquisition of multi-channel data is realized;
the STM32 minimum system is electrically connected with the communication module (6) through an RMII interface;
the polarity conversion circuit (2 a) comprises a capacitor C32, a capacitor C35 and a resistor R12, wherein one end of the capacitor C32 is electrically connected with the main control module (1), the other end of the capacitor C32 is grounded after passing through the resistor R12, and the connection point of the capacitor C32 and the resistor R12 is also grounded through the capacitor C35;
the gating circuit (2 b) comprises an analog switch U7, a resistor R4 to a resistor R11, a capacitor C7, a capacitor C9 and a capacitor C22 to a capacitor C29;
the analog switch U7 adopts a MAX4581CEE+ chip, and the 7 pin of the analog switch U7 is grounded after passing through a capacitor C9; the 16 pins of the analog switch U7 are grounded after passing through the capacitor C7; the 13 pin of the analog switch U7 is grounded after passing through the resistor R4, and the capacitor C22 is connected with the resistor R4 in parallel; the 14 pin of the analog switch U7 is grounded after passing through the resistor R5, and the capacitor C23 is connected with the resistor R5 in parallel; the 15 pin of the analog switch U7 is grounded after passing through the resistor R6, and the capacitor C24 is connected with the resistor R6 in parallel; the 12 pin of the analog switch U7 is grounded after passing through the resistor R7, and the capacitor C25 is connected with the resistor R7 in parallel; the 1 pin of the analog switch U7 is grounded after passing through a resistor R8, and a capacitor C26 is connected with the resistor R8 in parallel; the 5 pin of the analog switch U7 is grounded after passing through a resistor R9, and a capacitor C27 is connected with the resistor R9 in parallel; the 2 pin of the analog switch U7 is grounded after passing through the resistor R10, and the capacitor C28 is connected with the resistor R10 in parallel; the 4 pin of the analog switch U7 is grounded after passing through the resistor R11, and the capacitor C29 is connected with the resistor R11 in parallel;
The 3 pin of the analog switch U7 is electrically connected with the polarity conversion circuit (2 a);
the pins 12 to 15 of the analog switch U7 are also respectively and electrically connected with the amplifying circuit (2 c).
2. A gas-liquid two-phase flow monitoring system, characterized in that: comprising a computer end and the gas-liquid two-phase flow monitoring device according to claim 1;
the excitation module of the gas-liquid two-phase flow monitoring device adopts a cyclic scanning strategy, and each time sequentially transmits bipolar voltage excitation signals to one electrode wire at the excitation end of the wire mesh sensor, all response signals at the receiving end are subjected to current-to-voltage conversion, voltage amplification and AD conversion treatment, so that data acquisition of one electrode wire in the wire mesh sensor is completed; then exciting, receiving, processing again, and so on until the excitation of all electrode wires in the wire mesh sensor is completed, thereby obtaining a voltage matrix capable of reflecting the two-dimensional distribution of the conductivity at the section of the tested flow channel, obtaining phase state information of a complete section point, and transmitting the phase state information to a computer end in real time through a communication module;
the computer terminal is configured to: carrying out data analysis, data storage and section data imaging processing on the received phase state information of each complete section point, displaying the two-phase distribution characteristics of the section of the flow field, and calculating and displaying the section air content;
In the section data imaging processing, the intersection point of a silk screen sensor is taken as a pixel point, the measured value is taken as a corresponding pixel value, the pixel point of an image is increased by adopting an interpolation algorithm, and the image is filtered by adopting median filtering;
and adding pixels of the image by adopting a cubic spline interpolation method.
3. A gas-liquid two-phase flow monitoring system according to claim 2, characterized in that: the method for calculating the section air content is as follows:
converting the voltage value matrix into a gas phase gas content matrix:
where ε (i, j, k) represents the local air content of the kth frame data at coordinates (i, j), u gas (i, j) represents a calibration voltage value when all the measurement points with coordinates (i, j) are gas flowing through, u liquid (i, j) represents a calibration voltage value when all the measurement points with coordinates (i, j) are liquid flowing through, and u (i, j, k) represents a voltage value of the measurement point with coordinates (i, j) in the kth frame data;
calculating the section air content:
wherein ,
is the section air content; a, a i,j A weight value corresponding to a measured value of a measuring point with coordinates (i, j);
wherein ,Asensor Representing the total area of a circular cross section, A i,j Representing epsilon i,j Corresponding effective area.
4. A gas-liquid two-phase flow monitoring system according to claim 3, wherein: the computer side is further configured to: for viewing historical data, including tabular displays and view displays; the front view and the side view in the view reconstruct view information of the measuring pipeline by adopting a data projection method; front and side views are used to show the position of the bubble relative to the tube wall.
5. A gas-liquid two-phase flow monitoring method is characterized in that: a gas-liquid two-phase flow monitoring system according to any one of claims 2 to 4, the method comprising the steps of:
step 1, mounting a silk screen sensor on a cross section perpendicular to a flowing direction;
step 2, the excitation module adopts a cyclic scanning strategy, and each time sequentially transmits bipolar voltage excitation signals to one electrode wire at the excitation end of the screen sensor, and all response signals at the receiving end are subjected to current-to-voltage conversion, voltage amplification and AD conversion treatment, so that data acquisition of one electrode wire in the screen sensor is completed; then exciting, receiving, processing again, and so on until the excitation of all electrode wires in the wire mesh sensor is completed, thereby obtaining a voltage matrix capable of reflecting the two-dimensional distribution of the conductivity at the section of the tested flow channel, obtaining phase state information of a complete section point, and transmitting the phase state information to a computer end in real time through a communication module;
and 3, the computer end performs data analysis, data storage and section data imaging processing on the received phase state information of each complete section point, displays the two-phase distribution characteristics of the section of the flow field, and calculates and displays the section air content.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010451803.4A CN111610229B (en) | 2020-05-25 | 2020-05-25 | Gas-liquid two-phase flow monitoring device, system and method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010451803.4A CN111610229B (en) | 2020-05-25 | 2020-05-25 | Gas-liquid two-phase flow monitoring device, system and method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111610229A CN111610229A (en) | 2020-09-01 |
| CN111610229B true CN111610229B (en) | 2023-06-09 |
Family
ID=72196385
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010451803.4A Active CN111610229B (en) | 2020-05-25 | 2020-05-25 | Gas-liquid two-phase flow monitoring device, system and method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111610229B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112378980B (en) * | 2020-11-12 | 2021-09-21 | 上海交通大学 | Correction system and method for silk screen probe concentration detection device |
| CN113125524B (en) * | 2021-04-19 | 2023-01-20 | 上海交通大学 | Single-layer net type silk screen sensor |
| CN113984839A (en) * | 2021-11-02 | 2022-01-28 | 上海交通大学 | Novel capacitive silk screen sensor for high-conductivity fluid measurement |
| CN114689667B (en) * | 2022-03-28 | 2023-04-07 | 上海交通大学 | Method for measuring intersection mixing characteristic of two-phase flowing liquid in rod bundle channel based on silk screen |
| CN118590066A (en) * | 2024-08-06 | 2024-09-03 | 比亚迪股份有限公司 | Multichannel acquisition circuit, multichannel acquisition method, chip and vehicle |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102007004822A1 (en) * | 2006-01-31 | 2007-08-09 | NGK Spark Plug Co., Ltd., Nagoya | Liquid state detection sensor |
| CN101609066A (en) * | 2009-07-03 | 2009-12-23 | 天津大学 | A kind of electromagnetic sensing imaging system and method based on silk screen |
-
2020
- 2020-05-25 CN CN202010451803.4A patent/CN111610229B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102007004822A1 (en) * | 2006-01-31 | 2007-08-09 | NGK Spark Plug Co., Ltd., Nagoya | Liquid state detection sensor |
| CN101609066A (en) * | 2009-07-03 | 2009-12-23 | 天津大学 | A kind of electromagnetic sensing imaging system and method based on silk screen |
Non-Patent Citations (3)
| Title |
|---|
| 俞斌.基于丝网传感器的气水两相流可视化测量方法研究.《优秀硕士学位论文全文数据库》.2019,(第04期), * |
| 基于丝网传感器的气水两相流可视化测量方法研究;俞斌;《优秀硕士学位论文全文数据库》;20190415(第04期);摘要，第1-94页 * |
| 基于丝网传感器的气水两相流流型转换测量;孙圆圆;《传感技术学报》;20200315;第33卷(第03期);第364-369 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111610229A (en) | 2020-09-01 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111610229B (en) | Gas-liquid two-phase flow monitoring device, system and method | |
| Zhang et al. | Single-image super-resolution based on rational fractal interpolation | |
| CN109919844A (en) | A kind of high-resolution electricity tomography distribution of conductivity method for reconstructing | |
| CN101701973B (en) | Measuring data acquisition device and method thereof | |
| CN102901444B (en) | Method for detecting component size based on matching pursuit (MP) wavelet filtering and detecting system thereof | |
| CN102722706A (en) | Particle filter-based infrared small dim target detecting and tracking method and device | |
| CN107102031B (en) | Super-resolution imaging method for silk screen sensor | |
| CN109813772A (en) | A kind of stable imaging method of coplanar array capacitor | |
| CN111537032A (en) | Oil-gas two-phase flow parameter measuring device and method | |
| CN112345759A (en) | Method for detecting fluorescence intensity peak | |
| Ren et al. | Tomographic wire-mesh imaging of water-air flow based on sparse minimization | |
| CN112230236A (en) | Spectrum confocal displacement sensor distance measurement calculation method, system, device and storage medium | |
| Zhen et al. | Design and evaluation of an FFT-based space-time image velocimetry (STIV) for time-averaged velocity measurement | |
| CN109558041B (en) | GPU acceleration-based blade tip clearance signal acquisition, processing and transmission method | |
| CN104515473A (en) | Online diameter detection method of varnished wires | |
| CN101957458A (en) | Method for processing ultralow frequency data | |
| CN110243870B (en) | Water content measuring method based on dielectric loss tangent tomography technology | |
| CN2695964Y (en) | Oil-gas two-phase flow investigating device based-on capacitive chromatographic imaging system | |
| Wahab et al. | Image reconstruction for solid profile measurement in ERT using non-invasive approach | |
| Zhang et al. | Survey of EIT image reconstruction algorithms | |
| Lyu et al. | Image reconstruction for ultrasonic tomography using multi-channel convolutional neural network | |
| CN115931819A (en) | Raman spectrum denoising method, system, equipment and storage medium for insulating oil | |
| CN114636113A (en) | Oil depot pipeline leakage detection method | |
| CN109541309B (en) | Spectrum analyzer and signal processing method thereof | |
| CN113777139A (en) | Gas-liquid two-phase content rate detection method applying ECT with few electrodes |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |