CN107389974A - Gas-Liquid Slug Flow structure flow velocity acoustic-electric bimodal measuring method - Google Patents
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Abstract
The present invention relates to a kind of Gas-Liquid Slug Flow structure flow velocity acoustic-electric bimodal measuring method, is realized using twin crystal ultrasonic transducer and electric sensor, comprising：Gather the moisture content of electric sensor and the doppler shifted signal of sonac；Calculate the moisture content average th in the sampling timeH, by thHRegion division is carried out as the convection body of threshold value containing rate, Ye Dan areas moisture content average is calculated respectively using the gentle moisture content sequence for playing area in Ye Dan areasThe gentle moisture content average for playing areaAnd convection body carries out second zone and is divided into Qi Dan areas, mixed zone and Ye Dan areas；Using empirical mode decomposition, high frequency denoising is carried out to ultrasonic Doppler frequency shift signal；It is some intrinsic mode functions to reuse empirical mode decomposition；It is Doppler's average frequency shift in the time range of mixed zone to calculate liquid bullet portion, Doppler's average frequency shift in Ye Dan areas time range, Doppler's average frequency shift degree in liquid film time range；Calculate the structure flow velocity of slug flow.
Description
Technical Field
The invention belongs to the technical field of fluid measurement, and relates to a combined measurement method of an ultrasonic sensor and an electrical sensor.
Background
The gas-liquid two-phase flow is widely existed in the industrial production processes of petroleum, nuclear power units, chemical industry and the like, compared with the single-phase flow, the flow process of the gas-liquid two-phase flow has complex randomness, especially, an intermittent flow pattern is easily formed when the flow rate is high, the interaction between the gas phase and the liquid phase is more obvious, the severe pressure fluctuation causes strong impact on the pipeline, and even causes safety accidents when the pressure fluctuation is serious. Therefore, the measurement of the gas-liquid elastic flow structure flow velocity has important significance for model establishment, prediction and control of flow pattern conversion, and production safety and optimization.
The intermittency and transients in the bullet flow process present a significant challenge to flow rate measurement. The traditional test means mostly adopts an invasive measurement method, such as a conductance probe, a thermal film probe and the like, and disturbance is generated to the flow process while flow parameters are obtained, so that the measurement precision is influenced. In scientific research and industrial production processes, it is urgently needed to utilize a non-disturbance type measurement technology to accurately obtain process parameters of two-phase flow, so that an electrical method and an ultrasonic method are concerned due to non-invasion, simple sensor structure, convenience in installation and low cost.
The electrical measurement method is divided into various forms such as annular conductance array, capacitance polar plate, electrical impedance tomography and the like according to the difference of the structure, shape and excitation mode of the sensor, wherein the annular conductance array establishes an electrical sensitive field by applying constant excitation voltage on an excitation electrode pair, when the content of the measured fluid changes, the impedance characteristic of the sensitive field changes accordingly, the measurement of the content of the measured fluid is realized by acquiring the potential difference on the measurement electrode pair, and the method has good application prospect. Ultrasonic detection is used as a non-invasive method, and measures the flow velocity of fluid by utilizing the phenomena of reflection, refraction and the like of ultrasonic waves caused by different medium acoustic impedances when the ultrasonic waves are transmitted in the fluid, mainly comprises a correlation method, a time difference method, a Doppler method and the like, and has wide application in medicine and fluid measurement. The ultrasonic doppler technique based on continuous waves is based on the doppler effect, where ultrasonic waves are transmitted into a fluid by an ultrasonic transducer, reflected or scattered by a moving discrete phase (droplet or bubble) in a multiphase fluid, and then received by the ultrasonic transducer. The frequency difference between the incident sound wave and the received sound wave is proportional to the average flow velocity of the discrete-phase scattering particles in the measurement region. However, in the actual flowing process, complex occupancy distribution and flow velocity profile exist in the fluid, especially the gas bomb and liquid bomb appeared intermittently in the bullet flow, which causes the occupancy and flow velocity of the fluid to fluctuate greatly with time. Therefore, the doppler shift signal is a superposition of the ultrasonic doppler effect by scattering particles with different flow velocities at different positions, and is an aliasing signal containing fluctuation of multiple frequency scales. These fluctuations of different frequency scales reflect different flow rates during the fluid flow. Therefore, the electric sensor and the ultrasonic Doppler sensor are combined to obtain the content and flow rate information of the two-phase flow. And finally, acquiring the structural flow velocity of the gas-liquid bullet flow by a signal processing technology and a combined analysis method.
Disclosure of Invention
The invention aims to provide a novel method for measuring the flow velocity of a gas-liquid elastic flow structure based on signal empirical decomposition by utilizing an ultrasonic Doppler sensor and a conductivity sensor to obtain the flow velocity and the water content information of two-phase flow on the basis of the prior art. The technical scheme of the invention is as follows:
a gas-liquid elastic flow structure flow velocity acoustoelectric bimodal measurement method is realized by adopting a bimorph ultrasonic transducer and an electrical sensor, wherein the bimorph ultrasonic transducer is used for acquiring two-phase flow ultrasonic Doppler frequency shift signals, the electrical sensor is used for acquiring water content signals, the bimorph ultrasonic transducer adopts a receiving and transmitting integrated homonymy structure, is arranged at the bottom of a horizontal test pipeline and ensures that the included angle between the ultrasonic beam direction and the flow direction is theta; the electric sensor is composed of four annular metal electrodes embedded in the inner wall of a test pipeline, and is simultaneously installed in the test pipeline together with the ultrasonic transducer, and the measuring method comprises the following steps:
1) collecting water content signals H (T), T ∈ (0, T) of the electrical sensor and Doppler frequency shift signals f of the ultrasonic sensord(T), T ∈ (0, T), where T is the sampling time;
2) calculating the mean value of the water content in the sampling timeWill thHAnd (3) performing regional division on the fluid as a percentage threshold: if the water content is greater than th at a certain timeHIf the water content at the moment is the water content when the liquid elastic area flows through the electrical sensor, otherwise, the water content at the moment is the water content when the gas elastic area flows through the electrical sensor, namelyWherein Hnl，HngRespectively is a water content sequence of the liquid elastic area and the gas elastic area;
3) by means of Hnl、HngRespectively calculating the mean value of the water content of the liquid elastic areaMean value of water content of gas bomb mixing area Andwherein T isl，TgRespectively the time of the liquid bomb region and the time of the gas bomb region in the sampling time; will be provided withAndperforming secondary region division on the fluid as a percentage threshold: if the water content at a certain time is less thanThe time is that the air elastic area passes through the electrical sensor, and if the water content at a certain time is greater than that at a certain timeAnd is less thanThen the time is when the mixture passes through the electrical sensor, otherwise the liquid-elastic region passes through the electrical sensor, i.e.
The starting times T of the liquid elastic areas can be obtained respectively1Stop time T of the mixing zone2Start time T of the aeroelastic zone3And the stopping time of the gas-bomb zone, i.e. the starting time T of the next liquid-bomb zone4；
4) Carrying out high-frequency denoising treatment on the ultrasonic Doppler frequency shift signal by using empirical mode decomposition: based on empirical mode decomposition method, ultrasonic Doppler frequency shift signal f is obtainedd(T), T ∈ (0, T) are decomposed into a plurality of intrinsic mode functions IMF in a step-by-step mannerj(t), j ═ 1, 2.. times, n and trend function rnSum of (t):wherein n is the number of intrinsic mode functions obtained by decomposition, and each intrinsic mode function IMF is calculated by utilizing a cross-correlation methodj(t), j is 1, 2.. times, n is the correlation coefficient of the original Doppler frequency shift signal, and the correlation coefficient of the original Doppler frequency shift signal in the previous m stages is removed and is smaller than a threshold thccA high frequency eigenmode function component of (a); m is generally 3-4 thccGenerally, the value is 0.2-0.3; the correlation coefficient with the original Doppler frequency shift signal in the previous m stages is greater than or equal to thccThe remaining n-m order intrinsic mode functions and the trend function rn(t) adding and recombining to a new signal f to be processedd'(t),t∈(0,T)；
5) The signal f is decomposed by empirical moded'(t),t∈(0T) decomposition into several intrinsic mode functions IMFi(t), i ═ 1, 2.., N, and a trend term function rN(t) isWherein N is the number of intrinsic mode functions obtained by decomposition; selecting the first 4-level intrinsic mode function IMFi(t), i ═ 1,2,3,4 as the principal components;
6) and carrying out short-time Fourier transform on the main components to obtain time spectrum diagrams thereof, and determining the structural flow rates of the fluids respectively reflected by the main components through joint analysis with the electrical water content signals: first order Intrinsic Mode Function (IMF)1(t) is the highest frequency component, reflecting the propagation velocity of the liquid bullet in the bullet flow; second order Intrinsic Mode Function (IMF)2(t) covering the substantially covered liquid-elastic region, and the first order intrinsic mode function IMF1(t) together reflect the average flow velocity of the liquid elastic zone; third and fourth order intrinsic mode functions IMF3(t)&IMF4(t) occurs in the liquid film zone, is related to the droplet entrainment condition, and reflects the fluid flow velocity in the liquid film zone;
7) performing fast Fourier transform on the first-stage eigenmode function component and calculating Doppler average frequency shift in a liquid bullet part, namely a mixing region time range:performing fast Fourier transform on the sum of the first and second stage eigenmode function components and calculating the Doppler mean frequency shift in the time range of the liquid elastic regionPerforming fast Fourier transform on the sum of the third and fourth order eigenmode function components and calculating the Doppler mean frequency shift in the liquid film time rangeWherein f isd1，fd2，fd3Are respectively IMF1(t)，IMF1(t)+IMF2(t)，IMF3(t)+IMF4(t) corresponding frequencies, i.e. ultrasonic Doppler shifts at different scales, Sd1(fd1)，Sd2(fd2)，Sd3(fd3) Respectively, the corresponding energy spectrum intensities;
8) according to the basic principle of the Doppler effect, the structural flow velocity of the bullet flow is calculated: wherein the propagation speed of the liquid bomb is as follows:the average velocity of the liquid slugs is:the average flow velocity of the liquid membrane zone was:wherein f is0The excitation frequency of the ultrasonic reflection probe is theta, the included angle between the ultrasonic beam direction and the horizontal direction is theta, and c is the sound velocity in the fluid.
The invention has the substantive characteristics that: the electric sensor is used for acquiring a water content fluctuation signal of the gas-liquid elastic flow, and due to the strong reflection effect of gas relative to ultrasound, the ultrasonic Doppler sensor integrating receiving and transmitting at the same side is used for acquiring a Doppler frequency shift signal of the gas-liquid elastic flow. Because the gas bomb and the liquid bomb with obvious flow rate difference in the bullet-shaped flow occur intermittently, the water content and the flow rate fluctuate violently along with time. In addition, the flow velocity profile and the frequency-containing distribution exist, so that the Doppler frequency shift signal is the superposition of ultrasonic action from scatterers with different flow velocities at different positions and is a superposition signal of multi-frequency fluctuation. Therefore, a signal processing method based on empirical mode decomposition is adopted, Doppler signals are decomposed into a plurality of intrinsic mode functions, principal components reflecting the most significant characteristics of the signals are determined by adopting a cross-correlation algorithm, short-time Fourier transform analysis is carried out on the principal components, and the measurement of the flow velocity of the bullet-shaped flow structure is finally realized by combining the reflection of the water content on the intermittent characteristics of the bullet-shaped flow. The invention has the following beneficial effects and advantages:
1. the method is a non-disturbance type measuring means, and does not generate any disturbance to the fluid;
2. the combination of the electrical sensor and the ultrasonic Doppler sensor can obtain more comprehensive description of the fluid flow process;
3. the measurement of the structural flow velocity of the fluid is realized by a signal processing technology and a joint analysis method, and the method is simple and easy to implement;
4. the measurement is convenient, the speed is high, and the cost is low.
Drawings
Selected embodiments of the present invention are described in the following figures, which are exemplary, not exhaustive or limiting, and wherein:
FIG. 1 is a schematic diagram of an ultrasonic Doppler sensor in the measurement method of the present invention;
FIG. 2 is a schematic diagram of a conductive loop sensor structure in the measuring method of the present invention;
FIG. 3 is a schematic diagram of a structure of a bullet flow unit in the measurement method of the present invention;
FIG. 4 is a flow chart of empirical mode decomposition in the measurement method of the present invention;
FIG. 5 shows the calculation steps of the flow velocity of the bullet flow structure in the measurement method of the present invention.
Detailed Description
The following describes embodiments of the present invention in detail with reference to the drawings.
Fig. 1 is a schematic structural diagram of a continuous wave ultrasonic doppler sensor in the measurement method of the present invention. The ultrasonic Doppler probe used in the invention adopts a transmitting-receiving integrated double-crystal ultrasonic transducer, the interior of the ultrasonic Doppler probe comprises a transmitting piezoelectric ceramic wafer 3a and a receiving piezoelectric ceramic wafer 3b, and the transmitting piezoelectric ceramic wafer and the receiving piezoelectric ceramic wafer are respectively attached to an acoustoelectric coupling material 3c and a receiving piezoelectric ceramic wafer 3 d. Acoustic-electric coupling materialDirectly contacting the fluid and forming an angle theta with the horizontal pipe 10The ultrasonic beam passage is installed so as to maintain an angle theta with the incoming flow direction 0 of the two-phase flow 2. A sound insulating material 4 is added between the acoustic-electric coupling materials 3c and 3d to prevent interference between the transmitted and received sound waves. The double-crystal ultrasonic transducer is arranged at the bottom of the horizontal pipeline. The transmitting piezoelectric ceramic wafer 3a transmits ultrasonic waves, and the acoustic waves propagate in the fluid 2, are reflected and scattered by the discrete phases in the measurement space 5, and are received by the receiving piezoelectric ceramic wafer 3 b. The frequency difference between the received sound wave and the transmitted sound wave reflects the flow rate information of the fluid in the measurement space 5.
Fig. 2 is a schematic structural diagram of a conductive loop sensor in the measurement method of the present invention. The electric sensor used in the invention is formed by embedding four annular metal electrodes (1, 2,3, 4) in the inner wall 0 of the pipeline, wherein the electrode 1 and the electrode 4 are excitation electrode pairs, and the electrode 2 and the electrode 3 are measurement electrode pairs. By injecting a constant square wave excitation current into the electrode 1 and grounding the electrode 4, a stable electrically sensitive field can be formed between the electrodes 1 and 4. When the medium content and distribution of the fluid flowing through the sensitive field change, the potential difference between the electrode 2 and the electrode 3 changes, and the measurement of the fluid content can be realized by measuring the potential difference.
FIG. 3 is a schematic diagram of a structure of a bullet flow unit in the measurement method of the present invention. The gas-liquid bullet-shaped flow unit structure comprises a liquid bullet area 2 and a gas bullet area 3, and the turbulence intensity and the flow speed of fluid in the liquid bullet area 2 are higher than those of the gas bullet area 3. Because the head of the liquid bullet area continuously picks up the liquid dropped from the previous liquid bullet, when the high-speed liquid is fused with the low-speed liquid, a high-speed vortex is formed at the front end of the liquid bullet, a large number of discrete bubbles are distributed in the liquid phase, and the part is the mixing area 1. In the tail part of the liquid bullet, the liquid continuously returns to the liquid film area 4 due to the gravity, and the liquid undergoes a rapid deceleration process in the stage. At the front end of the gas bomb, the fluctuation of a gas-liquid interface is strong, liquid drops are entrained, and along with the time, the fluid flow is gradually stable and approximately wave-shaped flow flows slowly. The starting time of the liquid bullet area 2 in the bullet-shaped flow unit structure is T1At the moment of stopping of the mixing zone 1Is T2The start time of the gas bomb zone 3 is T3And the stop time of the gas bomb zone 3 (the start time of the next liquid bomb zone) is T4. The propagation speed of the liquid bomb in the bomb flow unit structure is VTThe average velocity of the liquid elastic region 2 is VSThe average flow velocity of the liquid film zone 4 is Vf。
Fig. 4 is a flowchart of empirical mode decomposition in the measurement method of the present invention. Empirical Mode Decomposition (EMD) is a self-adaptive time-frequency analysis method, wherein fluctuation of different scales existing in a signal x (t) is separated step by step through a screening process to generate a series of eigenmode functions (IMF) with different scales until a residual value sequence rn(t) stopping the decomposition for a monotonic function. Where each IMF needs to satisfy two basic conditions: 1) the number of signal extreme points (including maximum and minimum points) is equal to the number of zero-crossing points, or at most differs by 1; 2) at any time point of the signal, the mean value of an upper envelope line determined by local maximum values and a lower envelope line determined by local minimum value points is zero, and the signal is locally symmetrical about a time axis. The above-mentioned conditions are stop conditions for each screening process.
FIG. 5 is a flow chart of the steps of calculating the velocity of the bullet flow structure obtained by the ultrasonic and electrical combination sensor of the present invention. The calculation steps for obtaining the flow velocity of the bullet-shaped flow structure by the electricity and ultrasonic data combined analysis method are as follows:
step 1, collecting water content signals H (T), T ∈ (0, T) of an electrical sensor and Doppler frequency shift signals f of an ultrasonic sensord(T), T ∈ (0, T), where T is the sampling time;
step 2: and carrying out region division on the fluid of the gas-liquid bullet-shaped flow according to the water content signal.
1) Calculating the mean value of the water content in the sampling timeWill thHPerforming primary region division on the fluid as a percentage threshold: if the water content is greater than th at a certain timeHIf the water content at the moment is the water content when the liquid elastic area flows through the electrical sensor, otherwise, the water content at the moment is the water content when the gas elastic area flows through the electrical sensor, namely
Wherein Hnl，HngRespectively is a water content sequence of the liquid elastic area and the gas elastic area;
2) by means of Hnl、HngRespectively calculating the mean value of the water content of the liquid elastic areaMean value of water content of gas bomb mixing area Andwherein T isl，TgThe time elapsed in the liquid bomb zone and the gas bomb zone during the sampling time, respectively. Will be provided withAndperforming secondary region division on the fluid as a percentage threshold: if the water content at a certain time is less thanThe time is that the air elastic area passes through the electrical sensor, and if the water content at a certain time is greater than that at a certain timeAnd is less thanThen the time is when the mixture passes through the electrical sensor, otherwise the liquid-elastic region passes through the electrical sensor, i.e.
The starting times T of the liquid elastic areas can be obtained respectively1Stop time T of the mixing zone2Start time T of the aeroelastic zone3And the stop time T of the gas bomb zone (the start time of the next liquid bomb zone)4；
And step 3: and decomposing the Doppler frequency shift signal by an empirical mode decomposition-based method, and extracting the structural flow velocity of the bullet flow.
1) For Doppler frequency shift signal fdThe ultrasonic Doppler frequency shift signal f is firstly decomposed by an empirical mode to be denoisedd(T), T ∈ (0, T) are decomposed into a plurality of intrinsic mode functions IMF in a step-by-step mannerj(t), j ═ 1, 2.. times, n and trend function rnSum of (t):
wherein n is the number of eigenmode functions. It is worth noting that the essence of empirical mode decomposition is the screening process, and the termination condition of the screening, i.e. that each IMF needs to satisfy two basic conditions is difficult to satisfy, and the screening generally needs to be terminated by defining the standard deviation SD between adjacent decomposition results according to the cauchy convergence criterion, i.e.:
wherein,h1,k-1，h1,ktwo continuous decomposition result sequences are obtained in the screening process, SD generally takes values within the range of 0.2-0.3, and the selection of the SD can influence the number of decomposed intrinsic mode functions. And calculating the correlation coefficient of each intrinsic mode function and the original Doppler frequency shift signal by using a cross-correlation method, wherein the larger the correlation coefficient is, the more obvious the characteristic of the signal can be reflected by the intrinsic mode function. The correlation threshold th is therefore selected according to the actual high frequency noise situationccSelecting the first m-level high-frequency eigenmode function components for judgment: if the correlation coefficient of the first m-level high-frequency eigenmode function component and the original Doppler frequency shift signal is less than thccThen removal is selected, otherwise it is retained. Generally, the high-frequency noise is decomposed first due to the highest frequency, and the correlation coefficient with the original doppler shift signal is small, so m is generally 3-4 thccTypically, the value is 0.2-0.3. Then, the correlation coefficient between the previous m stages and the original Doppler frequency shift signal is greater than or equal to thccThe remaining n-m order intrinsic mode functions and the trend function rn(t) adding and recombining to a new signal f to be processedd'(t),t∈(0,T)；
2) New signal f to be processedd' (T), T ∈ (0, T) is subjected to quadratic empirical mode decomposition, the signal can be expressed as a plurality of intrinsic mode functions IMFi(t), i ═ 1, 2.., N, and trend function rNSum of (t):
wherein N is the number of intrinsic mode functions in the second decomposition. At each IMFiThe (t) includes the components of the signal in different frequency bands from high to low, and each IMF represents different time-scale characteristic components in the original signal. Since the empirical mode decomposition method may also be referred to as a principal component analysis method, in general, the most significant and important information in the signal is often concentrated in the preceding stage eigenmode function component obtained by the secondary decomposition. Thus selectively determining the first 4 eigenmodesState function IMFj(t), j is 1,2,3,4 as a principal component;
3) and (3) performing time-frequency analysis on the main components by using a short-time Fourier transform method, and determining the structural flow rates of the fluid respectively reflected by the main components by combining the partition results of the water content signals on the fluid in the step (2). Determining a first-stage intrinsic mode function IMF through the joint analysis of electrical and ultrasonic information1(t) is the highest frequency component, appears at the head of the liquid bullet area, and reflects the propagation speed of liquid bullets in the bullet-shaped flow; second order Intrinsic Mode Function (IMF)2(t) covering the substantially covered liquid-elastic region, and the first order intrinsic mode function IMF1(t) together reflect the average flow velocity of the liquid elastic zone; third and fourth order intrinsic mode functions IMF3(t)&IMF4(t) occurs in the liquid film zone, is related to the droplet entrainment condition, and reflects the fluid flow velocity in the liquid film zone;
4) performing fast Fourier transform on the first-stage eigenmode function component and calculating Doppler average frequency shift in a liquid bullet head (mixing region) time range:performing fast Fourier transform on the sum of the first and second stage eigenmode function components and calculating the Doppler mean frequency shift in the time range of the liquid elastic regionPerforming fast Fourier transform on the sum of the third and fourth order eigenmode function components and calculating the Doppler mean frequency shift in the liquid film time rangeWherein f isd1，fd2，fd3Are respectively asIMF1(t)+IMF2(t)，IMF3(t)+IMF4(t) corresponding to the frequency, i.e. the ultrasonic Doppler shift at different scales, Sd1 (f)d1)，Sd2(fd2)，Sd3(fd3) Respectively, the corresponding energy spectrum intensity, T1，T2，T3，T4Are obtained by step 2.
5) According to the basic principle of the Doppler effect, the structural flow velocity of the bullet flow is calculated: wherein the propagation speed of the liquid bomb is as follows:the average velocity of the liquid slugs (and at the same time the overall apparent flow rate of the slug flow) is:the average flow velocity of the liquid membrane zone was:wherein f is0The excitation frequency of the ultrasonic reflection probe is theta, the included angle between the ultrasonic beam direction and the horizontal direction is theta, and c is the sound velocity in the fluid.
Claims (1)
1. A gas-liquid elastic flow structure flow velocity acoustoelectric bimodal measurement method is realized by adopting a bimorph ultrasonic transducer and an electrical sensor, wherein the bimorph ultrasonic transducer is used for acquiring two-phase flow ultrasonic Doppler frequency shift signals, the electrical sensor is used for acquiring water content signals, the bimorph ultrasonic transducer adopts a receiving and transmitting integrated homonymy structure, is arranged at the bottom of a horizontal test pipeline and ensures that the included angle between the ultrasonic beam direction and the flow direction is theta; the electric sensor is composed of four annular metal electrodes embedded in the inner wall of a test pipeline, and is simultaneously installed in the test pipeline together with the ultrasonic transducer, and the measuring method comprises the following steps:
1) collecting water content signals H (T), T ∈ (0, T) of the electrical sensor and Doppler frequency shift signals f of the ultrasonic sensord(T), T ∈ (0, T), where T is the sampling time;
2) calculating the mean value of the water content in the sampling timeWill thHAnd (3) performing regional division on the fluid as a percentage threshold: if the water content is greater than th at a certain timeHIf the water content at the moment is the water content when the liquid elastic area flows through the electrical sensor, otherwise, the water content at the moment is the water content when the gas elastic area flows through the electrical sensor, namelyWherein Hnl，HngRespectively is a water content sequence of the liquid elastic area and the gas elastic area;
3) by means of Hnl、HngRespectively calculating the mean value of the water content of the liquid elastic areaMean value of water content of gas bomb mixing area Andwherein T isl，TgRespectively the time of the liquid bomb region and the time of the gas bomb region in the sampling time; will be provided withAndas the percentage of contentPerforming secondary region division on the fluid by using a threshold value: if the water content at a certain time is less thanThe time is that the air elastic area passes through the electrical sensor, and if the water content at a certain time is greater than that at a certain timeAnd is less thanThen the time is when the mixture passes through the electrical sensor, otherwise the liquid-elastic region passes through the electrical sensor, i.e.
The starting times T of the liquid elastic areas can be obtained respectively1Stop time T of the mixing zone2Start time T of the aeroelastic zone3And the stopping time of the gas-bomb zone, i.e. the starting time T of the next liquid-bomb zone4；
4) Carrying out high-frequency denoising treatment on the ultrasonic Doppler frequency shift signal by using empirical mode decomposition: based on empirical mode decomposition method, ultrasonic Doppler frequency shift signal f is obtainedd(T), T ∈ (0, T) are decomposed into a plurality of intrinsic mode functions IMF in a step-by-step mannerj(t), j ═ 1, 2.. times, n and trend function rnSum of (t):wherein n is the number of intrinsic mode functions obtained by decomposition, and each intrinsic mode function IMF is calculated by utilizing a cross-correlation methodj(t), j is 1, 2.. times, n is the correlation coefficient of the original Doppler frequency shift signal, and the correlation coefficient of the original Doppler frequency shift signal in the previous m stages is removed and is smaller than a threshold thccA high frequency eigenmode function component of (a); m is generally 3-4 thccGenerally, the value is 0.2-0.3; the correlation coefficient with the original Doppler frequency shift signal in the previous m stages is greater than or equal to thccIntrinsic mode function of (1), residualn-m order eigenmode function and trend function rn(t) are summed and recombined to a new signal f 'to be processed'd(t),t∈(0,T)；
5) The signal f 'is decomposed by using empirical mode again'd(T), T ∈ (0, T) is decomposed into several eigenmode functions IMFi(t), i ═ 1, 2.., N, and a trend term function rN(t) isWherein N is the number of intrinsic mode functions obtained by decomposition; selecting the first 4-level intrinsic mode function IMFi(t), i ═ 1,2,3,4 as the principal components;
6) and carrying out short-time Fourier transform on the main components to obtain time spectrum diagrams thereof, and determining the structural flow rates of the fluids respectively reflected by the main components through joint analysis with the electrical water content signals: first order Intrinsic Mode Function (IMF)1(t) is the highest frequency component, reflecting the propagation velocity of the liquid bullet in the bullet flow; second order Intrinsic Mode Function (IMF)2(t) covering the substantially covered liquid-elastic region, and the first order intrinsic mode function IMF1(t) together reflect the average flow velocity of the liquid elastic zone; third and fourth order intrinsic mode functions IMF3(t)&IMF4(t) occurs in the liquid film zone, is related to the droplet entrainment condition, and reflects the fluid flow velocity in the liquid film zone;
7) performing fast Fourier transform on the first-stage eigenmode function component and calculating Doppler average frequency shift in a liquid bullet part, namely a mixing region time range:performing fast Fourier transform on the sum of the first and second stage eigenmode function components and calculating the Doppler mean frequency shift in the time range of the liquid elastic regionPerforming fast Fourier transform on the sum of the third and fourth order eigenmode function components and calculating the Doppler mean frequency shift in the liquid film time rangeWherein f isd1，fd2，fd3Are respectively IMF1(t)，IMF1(t)+IMF2(t)，IMF3(t)+IMF4(t) corresponding frequencies, i.e. ultrasonic Doppler shifts at different scales, Sd1(fd1)，Sd2(fd2)，Sd3(fd3) Respectively, the corresponding energy spectrum intensities;
8) according to the basic principle of the Doppler effect, the structural flow velocity of the bullet flow is calculated: wherein the propagation speed of the liquid bomb is as follows:the average velocity of the liquid slugs is:the average flow velocity of the liquid membrane zone was:wherein f is0The excitation frequency of the ultrasonic reflection probe is theta, the included angle between the ultrasonic beam direction and the horizontal direction is theta, and c is the sound velocity in the fluid.
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