CN102269684A - Small-diameter pipeline liquid-liquid two-phase flow flow pattern identification system and method - Google Patents

Small-diameter pipeline liquid-liquid two-phase flow flow pattern identification system and method Download PDF

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CN102269684A
CN102269684A CN2011101680812A CN201110168081A CN102269684A CN 102269684 A CN102269684 A CN 102269684A CN 2011101680812 A CN2011101680812 A CN 2011101680812A CN 201110168081 A CN201110168081 A CN 201110168081A CN 102269684 A CN102269684 A CN 102269684A
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liquid
flow
capacitance
flow pattern
phase flow
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李霞
黄志尧
王磊
王保良
冀海峰
李海青
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Zhejiang University ZJU
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Zhejiang University ZJU
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Abstract

The invention discloses a small-diameter pipeline liquid-liquid two-phase flow flow pattern identification system and a method. The system comprises a transparent insulated pipeline, a capacitance sensor, a capacitance/voltage converter, a capacitance data acquisition unit, an optical sensor, a photocurrent/voltage converter, an optical data acquisition unit and a computer. Firstly the capacitance sensor and the optical sensor are used to simultaneously obtain a measuring signal which reflects the flow state change of liquid-liquid two-phase flow; the time domain characteristic quantity (mean value and standard deviation), the amplitude domain characteristic quantity (kurtosis and skewness of a probability density function curve) and the frequency domain characteristic quantity (energy percentages of the signals at different frequency bands) of the measuring signal are extracted; the characteristic quantity is inputted into a least squares support vector machine flow pattern classifier so as to finally realize the flow pattern identification of the small-diameter pipeline liquid-liquid two-phase flow. The invention has the advantages of no contact, high precision and the like, not only can effectively identify various flow patterns of small-diameter pipeline liquid-liquid two-phase flow, but also can provide beneficial reference for the measurement of other parameters of liquid-liquid two-phase flow.

Description

Small pipeline liquid-liquid two-phase flow pattern identification system and method
Technical Field
The invention relates to the field of multiphase flow measurement, in particular to a flow pattern identification system and method for small-pipeline liquid-liquid two-phase flow.
Background
The liquid-liquid two-phase flow system is widely used in the industrial fields of petroleum, daily chemicals, food, pharmacy and the like. In recent years, with the development of the miniaturization trend of industrial equipment, liquid-liquid two-phase flow systems of millimeter-scale small pipelines are researched and applied more and more, and the online detection of parameters of the millimeter-scale small pipelines is paid more and more attention. However, compared with the liquid-liquid two-phase flow at other scales, the mechanism research and the engineering application of the millimeter-scale small-pipeline liquid-liquid two-phase flow are relatively weak, and the corresponding detection technology is extremely lacking and needs to be strengthened urgently.
The flow pattern as an important parameter of the liquid-liquid two-phase flow not only affects the fluid dynamic characteristics and the heat and mass transfer performance of the two-phase flow, but also affects the accurate measurement of other parameters of the two-phase flow to a great extent. Therefore, the accurate identification of the flow pattern has important significance for the research and engineering application of the liquid-liquid two-phase flow. However, the flow characteristics of the liquid-liquid two-phase flow are very complex, and due to different dimensions, the liquid-liquid two-phase flow of the small pipe often shows different characteristics from the liquid-liquid two-phase flow of the conventional pipe diameter, which all pose higher requirements and challenges for flow pattern identification of the liquid-liquid two-phase flow of the small pipe. At present, the literature reports on the identification of the flow pattern of the liquid-liquid two-phase flow of the small pipeline are very limited, and the research and development are urgently needed.
Disclosure of Invention
The invention aims to overcome the defects of the existing research and technology and provide a flow pattern identification system and method for small-pipeline liquid-liquid two-phase flow.
The small pipeline liquid-liquid two-phase flow pattern identification system comprises a transparent insulating pipeline, a capacitance sensor, a capacitance/voltage converter, a capacitance data acquisition unit, an optical sensor, a photocurrent/voltage converter, an optical data acquisition unit and a computer; the capacitance sensor and the optical sensor are respectively arranged on the transparent insulating pipeline, the capacitance sensor is connected with the capacitance/voltage converter, the capacitance/voltage converter is connected with a computer through a capacitance data acquisition unit, the optical sensor is connected with the photocurrent/voltage converter, and the photocurrent/voltage converter is connected with the computer through the optical data acquisition unit.
The capacitance sensor is as follows: two metal electrodes with the same size, namely an excitation electrode and a detection electrode, are symmetrically adhered to the outer wall of the insulating pipeline relative to the central axis of the insulating pipeline, the excitation electrode is connected with a lead, the detection electrode is also connected with the lead, a protection electrode is arranged between the excitation electrode and the detection electrode and clings to the outer wall of the pipeline, the outer side of the whole measuring pipeline is wrapped by a metal shielding cover, and the protection electrode is connected with the metal shielding cover.
The optical sensor comprises a transparent pipeline, a laser, a cylindrical lens and a photocell, wherein the laser and the cylindrical lens are sequentially arranged on one side of the transparent pipeline, the optical axes of the laser and the cylindrical lens are vertical to the central axis of the transparent pipeline, and the photocell is arranged on the other side of the transparent pipeline on a plane vertical to the optical axes of the laser and the cylindrical lens.
The method for identifying the flow pattern of the liquid-liquid two-phase flow of the small pipeline comprises the following steps:
1) respectively and simultaneously obtaining measurement signals reflecting the flow state change of the liquid-liquid two-phase flow of the small pipeline by a capacitance sensor and an optical sensor, converting the capacitance measurement signals into voltage signals by a capacitance/voltage converter, sending the voltage signals to a computer by a capacitance data acquisition unit, and sending the voltage signals to the computer by an optical data acquisition unit after converting the optical measurement signals into the voltage signals by a photocurrent/voltage converter;
2) extracting time domain, amplitude domain and frequency domain characteristic quantities of a small pipeline liquid-liquid two-phase flow capacitance measurement signal and an optical measurement signal;
3) and inputting the extracted characteristic quantities of the capacitance measurement signal and the optical measurement signal into a flow pattern classifier established by a least square support vector machine, and identifying the flow pattern of the small-pipeline liquid-liquid two-phase flow on line.
The step 2) of extracting the time domain, amplitude domain and frequency domain characteristic quantities of the small pipeline liquid-liquid two-phase flow capacitance measurement signal and the optical measurement signal comprises the following steps:
(1) time domain feature quantity extraction
The extracted time domain characteristic quantity is the mean value and standard deviation of the small pipeline liquid-liquid two-phase flow measurement signal,
mean value:
Figure 156994DEST_PATH_IMAGE001
standard deviation:
Figure 2011101680812100002DEST_PATH_IMAGE002
wherein
Figure 2011101680812100002DEST_PATH_IMAGE003
In order to measure the time series of the signal,is a serial number of a time series,measuring the signal time sequence length;
(2) amplitude domain feature quantity extraction
The extracted amplitude domain characteristic quantity is the kurtosis of the probability density function curve of the small-pipeline liquid-liquid two-phase flow measurement signal
Figure 2011101680812100002DEST_PATH_IMAGE006
Degree of convergence
Figure 2011101680812100002DEST_PATH_IMAGE007
Kurtosis:
Figure 2011101680812100002DEST_PATH_IMAGE008
skewness:
wherein
Figure 2011101680812100002DEST_PATH_IMAGE010
Figure 2011101680812100002DEST_PATH_IMAGE011
Are respectively probability density function
Figure 2011101680812100002DEST_PATH_IMAGE012
The mean value and the standard deviation of (a),is the sequence number of the sequence of probability density functions,as a function of probability density
Figure 453895DEST_PATH_IMAGE012
Length of (d);
(3) empirical mode decomposition is carried out on the capacitance measurement signal and the optical measurement signal of the small pipeline liquid-liquid two-phase flow to obtain multilayer inherent modal function components, the percentage of the energy of the first 12 layers of inherent modal function components in the total energy of all the inherent modal function components is calculated,
Figure 2011101680812100002DEST_PATH_IMAGE015
wherein,
Figure 2011101680812100002DEST_PATH_IMAGE016
the percentage of the energy of the ith layer natural mode function component to the total energy of all the natural mode function components,
Figure 2011101680812100002DEST_PATH_IMAGE017
is the energy of the i-th layer natural mode function component,
Figure 2011101680812100002DEST_PATH_IMAGE018
when the number of layers of the inherent mode function components obtained by the empirical mode decomposition of the signal is less than 12, the vacant energy percentage is replaced by zero;
(4) obtaining 32 characteristic quantities representing flow pattern characteristics of small pipeline liquid-liquid two-phase flow
Figure 2011101680812100002DEST_PATH_IMAGE019
Wherein,
Figure 2011101680812100002DEST_PATH_IMAGE020
the signal characteristic quantities are measured for 16 capacitances,
Figure 2011101680812100002DEST_PATH_IMAGE021
the signal characteristic quantities are measured for 16 optical measurements.
Inputting the extracted characteristic quantities of the capacitance measurement signal and the optical measurement signal into a flow pattern classifier established by a least square support vector machine, and performing online identification on the flow pattern of the small-pipeline liquid-liquid two-phase flow, wherein the step 3) is as follows:
for the identified multiple small pipeline liquid-liquid two-phase flow patterns, two types of classifiers based on a least square support vector machine are designed between every two flow patterns, and the decision function of each flow pattern classifier has the following form:
wherein,
Figure 2011101680812100002DEST_PATH_IMAGE023
in order to train the sample set,
Figure 2011101680812100002DEST_PATH_IMAGE024
in order to be a characteristic quantity of the image,
Figure 2011101680812100002DEST_PATH_IMAGE025
are labeled for the purpose of a category,
Figure 2011101680812100002DEST_PATH_IMAGE026
in order to train the sample numbers of the set,
Figure 2011101680812100002DEST_PATH_IMAGE027
in order to train the number of samples in the set,
Figure 2011101680812100002DEST_PATH_IMAGE028
for the characteristic quantity of the flow pattern sample to be tested,
Figure 2011101680812100002DEST_PATH_IMAGE029
and
Figure 2011101680812100002DEST_PATH_IMAGE030
for the trained determined least squares support vector machine parameters,
Figure 2011101680812100002DEST_PATH_IMAGE031
in order to be a kernel function, the kernel function,
Figure 975576DEST_PATH_IMAGE011
is a parameter of the kernel function;
for the flow pattern sample to be tested, firstly, the characteristic quantities of the signals in a time domain, an amplitude domain and a frequency domain are extracted, then the extracted characteristic quantities are input into each classifier for testing, a ticket is cast to the corresponding flow pattern according to the test result, and finally the flow pattern with the most tickets is used as the current flow pattern identification result.
The invention provides a flow pattern identification system and method for small-pipeline liquid-liquid two-phase flow. The method has the advantages of non-contact, high identification precision and the like, not only provides a feasible and effective way for identifying the flow pattern of the small-pipeline liquid-liquid two-phase flow, but also provides a beneficial reference for measuring other parameters of the small-pipeline liquid-liquid two-phase flow.
Drawings
FIG. 1 is a block diagram of a flow pattern identification system for a small pipe liquid-liquid two-phase flow;
FIG. 2 is a schematic diagram of a capacitive sensor construction of the present invention;
FIG. 3 is a schematic diagram of the optical sensor configuration of the present invention;
FIG. 4 is a flow chart of a flow pattern identification method for a small pipe liquid-liquid two-phase flow.
Detailed Description
Aiming at the current situation that a flow pattern identification method of liquid-liquid two-phase flow of a small pipeline is lacked, the invention provides a system and a method for identifying the flow pattern of the liquid-liquid two-phase flow of the small pipeline by comprehensively utilizing advanced information processing technologies such as a capacitance sensor, an optical sensor, a Probability Density Function (PDF), Empirical Mode Decomposition (EMD) and Least square Support Vector machine (LS-SVM). The method has the advantages of non-contact, high precision and the like, and can effectively identify various flow patterns of the small-pipeline liquid-liquid two-phase flow.
As shown in fig. 1, the small pipe liquid-liquid two-phase flow pattern identification system includes a transparent insulated pipe, a capacitance sensor, a capacitance/voltage converter, a capacitance data acquisition unit, an optical sensor, a photocurrent/voltage converter, an optical data acquisition unit, and a computer; the capacitance sensor and the optical sensor are respectively arranged on the transparent insulating pipeline, the capacitance sensor is connected with the capacitance/voltage converter, the capacitance/voltage converter is connected with a computer through a capacitance data acquisition unit, the optical sensor is connected with the photocurrent/voltage converter, and the photocurrent/voltage converter is connected with the computer through the optical data acquisition unit.
As shown in fig. 2, the capacitive sensor is: two metal electrodes with the same size, namely an excitation electrode 1 and a detection electrode 2, are symmetrically adhered to the outer wall of an insulating pipeline 3 relative to the central axis of the insulating pipeline, the excitation electrode is connected with a lead 4, the detection electrode is connected with a lead 5, a protection electrode 6 is arranged between the excitation electrode and the detection electrode and clings to the outer wall of the pipeline, the outer side of the whole measuring pipeline is wrapped by a metal shielding cover 7, and the protection electrode is connected with the metal shielding cover.
As shown in fig. 3, the optical sensor includes a transparent pipe, a laser, a cylindrical lens and a photocell, the laser and the cylindrical lens are sequentially installed at one side of the transparent pipe, optical axes of the laser and the cylindrical lens are perpendicular to a central axis of the transparent pipe, and the photocell is installed at a plane perpendicular to the optical axes of the laser and the cylindrical lens at the other side of the transparent pipe. When the sensor works, the point light source generated by the laser is converted into sheet light after passing through the cylindrical lens, the sheet light is orthogonally projected onto the transparent pipeline as incident light, passes through the liquid-liquid two-phase flow in the pipeline, is emitted from the other side of the transparent pipeline and is projected onto the photocell, and the photocell converts the detected light intensity into a current signal to be output.
In the actual online flow pattern identification process, liquid-liquid two-phase flow enters a measuring pipeline and flows through a capacitance sensor and an optical sensor. The capacitance measurement signal obtained by the capacitance sensor is converted into a voltage signal by a capacitance/voltage converter, and then is sent to a computer by a capacitance data acquisition unit. The optical measurement signal obtained by the optical sensor is converted into a voltage signal by a photocurrent/voltage converter, and then is sent to a computer by an optical data acquisition unit. The computer stores, analyzes and calculates the obtained capacitance measurement signal and optical measurement signal.
As shown in fig. 4, the method for identifying the flow pattern of the liquid-liquid two-phase flow in the small pipeline comprises the following steps:
1) respectively and simultaneously obtaining measurement signals reflecting the flow state change of the liquid-liquid two-phase flow of the small pipeline by a capacitance sensor and an optical sensor, converting the capacitance measurement signals into voltage signals by a capacitance/voltage converter, sending the voltage signals to a computer by a capacitance data acquisition unit, and sending the voltage signals to the computer by an optical data acquisition unit after converting the optical measurement signals into the voltage signals by a photocurrent/voltage converter;
2) extracting time domain, amplitude domain and frequency domain characteristic quantities of a small pipeline liquid-liquid two-phase flow capacitance measurement signal and an optical measurement signal;
3) and inputting the extracted characteristic quantities of the capacitance measurement signal and the optical measurement signal into a flow pattern classifier established by a least square support vector machine, and identifying the flow pattern of the small-pipeline liquid-liquid two-phase flow on line.
The step 2) of extracting the time domain, amplitude domain and frequency domain characteristic quantities of the small pipeline liquid-liquid two-phase flow capacitance measurement signal and the optical measurement signal comprises the following steps:
(1) time domain feature quantity extraction
The extracted time domain characteristic quantity is the mean value and standard deviation of the small pipeline liquid-liquid two-phase flow measurement signal,
mean value:
Figure 433102DEST_PATH_IMAGE001
standard deviation:
Figure 559059DEST_PATH_IMAGE002
wherein
Figure 381521DEST_PATH_IMAGE003
In order to measure the time series of the signal,
Figure 710871DEST_PATH_IMAGE004
is a serial number of a time series,
Figure 722821DEST_PATH_IMAGE005
measuring the signal time sequence length;
(2) amplitude domain feature quantity extraction
Extracted amplitude feature quantityPeak degree of signal probability density function curve for small pipeline liquid-liquid two-phase flow measurement
Figure 391699DEST_PATH_IMAGE006
Degree of convergence
Figure 447380DEST_PATH_IMAGE007
Kurtosis:
skewness:
Figure 250306DEST_PATH_IMAGE009
wherein
Figure 836008DEST_PATH_IMAGE010
Figure 78902DEST_PATH_IMAGE011
Are respectively probability density function
Figure 320527DEST_PATH_IMAGE012
The mean value and the standard deviation of (a),
Figure 657968DEST_PATH_IMAGE013
is the sequence number of the sequence of probability density functions,
Figure 613023DEST_PATH_IMAGE014
as a function of probability density
Figure 948189DEST_PATH_IMAGE012
Length of (d);
(3) and performing empirical mode decomposition on the capacitance measurement signal and the optical measurement signal of the small-pipeline liquid-liquid two-phase flow to obtain a multilayer inherent modal function component.
According to the characteristics of the signal, the EMD decomposes the original signal into the sum of finite layer natural mode function components according to the sequence of the frequency from high to low, and each layer of natural mode function component contains the local characteristic information of the original signal. The empirical mode function component of each layer needs to satisfy the following two conditions: 1) in the whole empirical mode function component data sequence section, the number of zero points is equal to the number of poles or the difference is 1, 2) for any data point, the envelope of the local maximum value and the envelope mean value of the local minimum value are zero. According to this rule, the eigenmode function components are "filtered" one by one until the time series becomes a monotonic function. Finally, the raw measurement signal is decomposed into the sum of the multilayer eigenmode function components and the trend term, i.e.:
wherein,
Figure 2011101680812100002DEST_PATH_IMAGE033
in order to obtain a mean-removed measurement signal,is composed of
Figure DEST_PATH_IMAGE035
The characteristic frequency of the signal represented by the layer natural mode function component is gradually reduced,
Figure 2011101680812100002DEST_PATH_IMAGE036
the trend term represents the monotonous trend of the signal after all the natural modal function components are extracted.
The percentage of the energy of the first 12 layers of natural modal function components in the total energy of all the natural modal function components is calculated,
Figure DEST_PATH_IMAGE037
wherein,
Figure 994555DEST_PATH_IMAGE016
the percentage of the energy of the ith layer natural mode function component to the total energy of all the natural mode function components,
Figure 886419DEST_PATH_IMAGE017
is the energy of the i-th layer natural mode function component,
Figure 446713DEST_PATH_IMAGE018
when the number of layers of the inherent mode function components obtained by the empirical mode decomposition of the signal is less than 12, the vacant energy percentage is replaced by zero;
(4) obtaining 32 characteristic quantities representing flow pattern characteristics of small pipeline liquid-liquid two-phase flow
Figure 2011101680812100002DEST_PATH_IMAGE038
Wherein,
Figure 529944DEST_PATH_IMAGE020
the signal characteristic quantities are measured for 16 capacitances,
Figure 542900DEST_PATH_IMAGE021
the signal characteristic quantities are measured for 16 optical measurements.
Inputting the extracted characteristic quantities of the capacitance signal and the optical signal into a flow pattern classifier established by a least square support vector machine, and performing online identification on the flow pattern of the small-pipeline liquid-liquid two-phase flow, wherein the step 3) is as follows:
for a variety of identified small pipe liquid-liquid two-phase flow patterns, such as: the method comprises the following steps of (1) plug flow, laminar flow, oil-based bubble flow, water-based bubble flow, oil core annular flow and water core annular flow, wherein two types of classifiers based on a least square support vector machine are designed between every two flow types, the six typical flow types are totally 15 types of classifiers, and a decision function of each flow type classifier has the following form:
Figure 425405DEST_PATH_IMAGE022
wherein,
Figure 590938DEST_PATH_IMAGE023
in order to train the sample set,
Figure 595803DEST_PATH_IMAGE024
in order to be a characteristic quantity of the image,
Figure 33738DEST_PATH_IMAGE025
is a flow pattern class designation,
Figure 765939DEST_PATH_IMAGE026
in order to train the sample numbers of the set,in order to train the number of samples in the set,
Figure 414276DEST_PATH_IMAGE028
for the characteristic quantity of the flow pattern sample to be tested,
Figure 152556DEST_PATH_IMAGE029
and
Figure 439180DEST_PATH_IMAGE030
for the trained determined least squares support vector machine parameters,
Figure 812262DEST_PATH_IMAGE031
in order to be a kernel function, the kernel function,
Figure 96613DEST_PATH_IMAGE011
is a parameter of the kernel function;
for the flow pattern sample to be tested, firstly, the characteristic quantities of the signals in a time domain, an amplitude domain and a frequency domain are extracted, then the extracted characteristic quantities are input into each classifier for testing, a ticket is cast to the corresponding flow pattern according to the test result, and finally the flow pattern with the most tickets is used as the current flow pattern identification result.
Two-phase oil-water flow experiments have been performed on small horizontal pipes with an internal diameter of 1.8mm, 3.1mm and 4.0mm, respectively. Six typical flow patterns of oil-water two-phase flow are realized by using the system and the method provided by the invention: the online identification of plug flow, laminar flow, oil-based bubble flow, water-based bubble flow, oil core annular flow and water core annular flow, and the identification result of the oil-water two-phase flow pattern under each pipe diameter is shown in table 1. Experimental results show that the flow pattern identification system and method for the liquid-liquid two-phase flow of the small pipe, provided by the invention, are effective, satisfactory flow pattern identification accuracy is obtained, and the identification accuracy of each typical flow pattern under each pipe diameter is over 96%.
TABLE 1 identification result of oil-water two-phase flow pattern under each pipe diameter
Number of samples in training set Number of samples in test set Number of misclassified samples Flow pattern identification accuracy (%)
ID=1.8mm 198 99 2 97.98%
ID=3.1mm 206 103 0 100%
ID=4.0mm 190 95 3 96.84%

Claims (6)

1. A flow pattern identification system for liquid-liquid two-phase flow of a small pipeline is characterized by comprising a transparent insulating pipeline, a capacitance sensor, a capacitance/voltage converter, a capacitance data acquisition unit, an optical sensor, a photocurrent/voltage converter, an optical data acquisition unit and a computer; the capacitance sensor and the optical sensor are respectively arranged on the transparent insulating pipeline, the capacitance sensor is connected with the capacitance/voltage converter, the capacitance/voltage converter is connected with a computer through a capacitance data acquisition unit, the optical sensor is connected with the photocurrent/voltage converter, and the photocurrent/voltage converter is connected with the computer through the optical data acquisition unit.
2. The system according to claim 1, wherein the capacitive sensor is: two metal electrodes with the same size, namely an excitation electrode (1) and a detection electrode (2), are symmetrically adhered to the outer wall of the insulating pipeline (3) relative to the central axis of the insulating pipeline (3), the excitation electrode is connected with a lead (4), the detection electrode is connected with a lead (5), a protection electrode (6) is arranged between the excitation electrode and the detection electrode and clings to the outer wall of the pipeline, the outer side of the whole measuring pipeline is wrapped by a metal shielding cover (7), and the protection electrode is connected with the metal shielding cover.
3. The two-phase flow pattern recognition system according to claim 1, wherein the optical sensor comprises a transparent pipe, a laser, a cylindrical lens and a photocell, the laser and the cylindrical lens are sequentially mounted on one side of the transparent pipe, optical axes of the laser and the cylindrical lens are perpendicular to a central axis of the transparent pipe, and the photocell is mounted on the other side of the transparent pipe on a plane perpendicular to the optical axes of the laser and the cylindrical lens.
4. A method for identifying the flow pattern of a small pipe liquid-liquid two-phase flow by using the system of claim 1, comprising the steps of:
1) respectively and simultaneously obtaining measurement signals reflecting the flow state change of the liquid-liquid two-phase flow by a capacitance sensor and an optical sensor, converting the capacitance measurement signals into voltage signals by a capacitance/voltage converter, sending the voltage signals to a computer by a capacitance data acquisition unit, and sending the voltage signals to the computer by an optical data acquisition unit after converting the optical measurement signals into the voltage signals by a photocurrent/voltage converter;
2) extracting time domain, amplitude domain and frequency domain characteristic quantities of a small pipeline liquid-liquid two-phase flow capacitance measurement signal and an optical measurement signal;
3) and inputting the extracted characteristic quantities of the capacitance measurement signal and the optical measurement signal into a flow pattern classifier established by a least square support vector machine, and identifying the flow pattern of the small-pipeline liquid-liquid two-phase flow on line.
5. The method for identifying the flow pattern of the small pipe liquid-liquid two-phase flow according to claim 4, wherein the step of extracting the time domain, amplitude domain and frequency domain characteristic quantities of the small pipe liquid-liquid two-phase flow capacitance measurement signal and the optical measurement signal in step 2) comprises the steps of:
(1) time domain feature quantity extraction
The extracted time domain characteristic quantity is the mean value and standard deviation of the small pipeline liquid-liquid two-phase flow measurement signal,
mean value:
Figure 2011101680812100001DEST_PATH_IMAGE001
standard deviation:
Figure 791631DEST_PATH_IMAGE002
wherein
Figure 2011101680812100001DEST_PATH_IMAGE003
In order to measure the time series of the signal,
Figure 311474DEST_PATH_IMAGE004
is a serial number of a time series,
Figure 2011101680812100001DEST_PATH_IMAGE005
to measure the length of the signal time series;
(2) amplitude domain feature quantity extraction
The extracted amplitude domain characteristic quantity is the kurtosis of the probability density function curve of the small-pipeline liquid-liquid two-phase flow measurement signal
Figure 63529DEST_PATH_IMAGE006
Degree of convergence
Figure 2011101680812100001DEST_PATH_IMAGE007
Kurtosis:
Figure 10626DEST_PATH_IMAGE008
skewness:
wherein
Figure 464610DEST_PATH_IMAGE010
Figure 2011101680812100001DEST_PATH_IMAGE011
Are respectively probability density function
Figure 601193DEST_PATH_IMAGE012
The mean value and the standard deviation of (a),
Figure 2011101680812100001DEST_PATH_IMAGE013
is the sequence number of the sequence of probability density functions,
Figure 457022DEST_PATH_IMAGE014
as a function of probability density
Figure 388069DEST_PATH_IMAGE012
Length of (d);
(3) empirical mode decomposition is carried out on the capacitance measurement signal and the optical measurement signal of the small pipeline liquid-liquid two-phase flow to obtain multilayer inherent modal function components, the percentage of the energy of the first 12 layers of inherent modal function components in the total energy of all the inherent modal function components is calculated,
Figure 2011101680812100001DEST_PATH_IMAGE015
wherein,
Figure 323490DEST_PATH_IMAGE016
the percentage of the energy of the ith layer natural mode function component to the total energy of all the natural mode function components,
Figure 2011101680812100001DEST_PATH_IMAGE017
is the energy of the i-th layer natural mode function component,
Figure 998185DEST_PATH_IMAGE018
when the number of layers of the natural mode function components obtained by the empirical mode decomposition of the signal is less than 12, the vacant energy percentage is replaced by zero;
(4) obtaining 32 characteristic quantities representing flow pattern characteristics of small pipeline liquid-liquid two-phase flow
Figure DEST_PATH_IMAGE019
Wherein,
Figure 708521DEST_PATH_IMAGE020
the signal characteristic quantities are measured for 16 capacitances,
Figure DEST_PATH_IMAGE021
the signal characteristic quantities are measured for 16 optical measurements.
6. The method for identifying the flow pattern of the two-phase liquid-liquid flow in the small pipe according to claim 4, wherein the step 3) of inputting the extracted characteristic quantities of the capacitance measurement signal and the optical measurement signal into the flow pattern classifier established by the least squares support vector machine comprises the steps of:
for the identified multiple small pipeline liquid-liquid two-phase flow patterns, two types of classifiers based on a least square support vector machine are designed between every two flow patterns, and the decision function of each flow pattern classifier has the following form:
Figure 76048DEST_PATH_IMAGE022
wherein,
Figure DEST_PATH_IMAGE023
in order to train the sample set,
Figure 504624DEST_PATH_IMAGE024
in order to be a characteristic quantity of the image,
Figure DEST_PATH_IMAGE025
is a flow pattern class designation,in order to train the sample numbers of the set,in order to train the number of samples in the set,
Figure 904382DEST_PATH_IMAGE030
for the characteristic quantity of the flow pattern sample to be tested,and
Figure 485536DEST_PATH_IMAGE032
for the trained determined least squares support vector machine parameters,
Figure DEST_PATH_IMAGE033
in order to be a kernel function, the kernel function,
Figure 7653DEST_PATH_IMAGE011
is a parameter of the kernel function;
for the flow pattern sample to be tested, firstly, the characteristic quantities of the signals in a time domain, an amplitude domain and a frequency domain are extracted, then the extracted characteristic quantities are input into each classifier for testing, a ticket is cast to the corresponding flow pattern according to the test result, and finally the flow pattern with the most tickets is used as the current flow pattern identification result.
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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102590030A (en) * 2012-01-18 2012-07-18 浙江大学 Small-passage gas-liquid phase flow pattern identification device and method based on photovoltaic array sensor
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CN105527226A (en) * 2016-01-20 2016-04-27 浙江大学 Photoelectric diode array sensor-based ductule gas-liquid two-phase parameter measurement device and method
CN105842273A (en) * 2016-03-16 2016-08-10 华北电力大学(保定) Acquiring method and system for compression factor
CN109557146A (en) * 2019-01-11 2019-04-02 南京工程学院 A kind of apparatus for detecting disconnection of diamond wire and its prediction technique that breaks
CN110595948A (en) * 2019-08-27 2019-12-20 杭州电子科技大学 Small-channel two-phase flow parameter measuring device and method based on annular optical array
CN111191398A (en) * 2019-12-06 2020-05-22 云南电网有限责任公司玉溪供电局 SVR-based method for predicting degradation trend of storage battery of direct-current system of transformer substation

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CN102590030A (en) * 2012-01-18 2012-07-18 浙江大学 Small-passage gas-liquid phase flow pattern identification device and method based on photovoltaic array sensor
CN103674478A (en) * 2013-12-11 2014-03-26 中国石油大学(华东) Low-gas-content gas-liquid two phase flow pattern identifying method
CN103674478B (en) * 2013-12-11 2016-01-06 中国石油大学(华东) The Method for Discriminating Gas-liquid Two Phase Flow of low air void
CN105527226A (en) * 2016-01-20 2016-04-27 浙江大学 Photoelectric diode array sensor-based ductule gas-liquid two-phase parameter measurement device and method
CN105842273A (en) * 2016-03-16 2016-08-10 华北电力大学(保定) Acquiring method and system for compression factor
CN105842273B (en) * 2016-03-16 2018-08-28 华北电力大学(保定) A kind of acquisition methods and system of compressibility factor
CN109557146A (en) * 2019-01-11 2019-04-02 南京工程学院 A kind of apparatus for detecting disconnection of diamond wire and its prediction technique that breaks
CN109557146B (en) * 2019-01-11 2024-02-13 南京工程学院 Diamond wire breakage detection device and breakage prediction method thereof
CN110595948A (en) * 2019-08-27 2019-12-20 杭州电子科技大学 Small-channel two-phase flow parameter measuring device and method based on annular optical array
CN111191398A (en) * 2019-12-06 2020-05-22 云南电网有限责任公司玉溪供电局 SVR-based method for predicting degradation trend of storage battery of direct-current system of transformer substation

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