CN107389974A - Gas-Liquid Slug Flow structure flow velocity acoustic-electric bimodal measuring method - Google Patents
Gas-Liquid Slug Flow structure flow velocity acoustic-electric bimodal measuring method Download PDFInfo
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- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
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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 fluid measurement technical field, is related to a kind of sonac and electric sensor combined type measurement side
Method, by decomposing Doppler's test signal, realize that the non-disturbance formula of the structure flow velocity of Gas-Liquid Slug Flow obtains.
Background technology
Biphase gas and liquid flow is widely present in the industrial processes such as oil, nuclear power generating sets, chemical industry, compared with single-phase flow,
Complicated randomness is presented in its flow process, and interval flow pattern is especially easily formed when flow velocity is higher, now gas-liquid two-phase it
Between interaction it is more obvious, violent pressure oscillation causes strong impact to pipeline, when serious even trigger safe thing
Therefore.Therefore, the measurement to Gas-Liquid Slug Flow structure flow velocity is for model foundation, the prediction of Regime transition and control, production safety
It is significant with optimizing.
Intermittence and transient state in slug flow flow process are that flow velocity measurement brings huge challenge.Traditional test
Means use intrusive mood measuring method, such as conducting probe, hotting mask probe more, can be to flowing over while flow parameter is obtained
Journey produces disturbance, influences measurement accuracy.In scientific research and industrial processes, it is badly in need of accurate using non-disturbance formula e measurement technology
Really obtain the procedure parameter of two phase flow, thus electric method, ultrasonic method are due to its non-intruding, sensor construction is simple, it is easy for installation,
Cost is cheap and receives much concern.
Electric measurement method is divided into annular photoconductive array, electric capacity according to the structure of sensor, shape, the difference of energisation mode
The diversified forms such as pole plate, electrical impedance tomography, wherein annular photoconductive array in exciting electrode to upper apply by constant swashing
Voltage Establishment electricity sensitivity field is encouraged, when detected fluid changes containing rate, the impedance operator of sensitivity field changes therewith,
Measurement of the detected fluid containing rate is realized to upper electrical potential difference by obtaining measuring electrode, there is good application prospect.Ultrasound inspection
Survey and be used as a kind of non-invasive methods, occur when being propagated in a fluid using ultrasound caused by different medium acoustic impedance difference anti-
Phenomena such as penetrating, reflecting and the flow velocity of convection body measures, mainly including correlation method, time difference method, Doppler method etc., medical science,
Have in fluid measurement and be widely applied very much.Ultrasonic Doppler technique based on continuous wave is based on Doppler effect, ultrasonic wave by
Ultrasonic transducer is emitted into fluid, after the reflection or scattering of the discrete phase (drop or bubble) moved in heterogeneous fluid by
Ultrasonic transducer receives.Frequency difference and the average flowing of discrete phase scattering particles in measured zone between incident acoustic wave and reception sound wave
Speed is directly proportional.But in actual flow process, especially shape is being played containing rate distribution and fluid velocity profile in the presence of complicated in fluid
The gas bullet and liquid bullet intermittently occurred in stream, there are big ups and downs in that causes fluid containing rate and flow velocity with the time.Therefore, Doppler's frequency
Shifting signal is that have the superposition of scattering particles different in flow rate to ultrasonic Doppler effect on diverse location, is that one kind includes multifrequency
The aliasing signal of rate yardstick fluctuation.Different flow velocitys in the fluctuation reflection process fluid flow of these different frequency yardsticks.Cause
This, electric sensor and ultrasonic Doppler sensor combinations is used, obtain two phase flow contains rate and flow rate information.Pass through signal
Treatment technology and conjoint analysis method, finally realize the acquisition of the structure flow velocity of Gas-Liquid Slug Flow.
The content of the invention
The purpose of the present invention is on the basis of existing technology, to be obtained using ultrasonic Doppler sensor and conductivity sensor
The flow velocity and moisture content information of two phase flow, there is provided a kind of survey of the new Gas-Liquid Slug Flow structure flow velocity decomposed based on signal experience
Amount method.Technical scheme is as follows：
A kind of Gas-Liquid Slug Flow structure flow velocity acoustic-electric bimodal measuring method, sensed using twin crystal ultrasonic transducer and electricity
Device realizes that twin crystal ultrasonic transducer is used to obtain two phase flow ultrasonic Doppler frequency shift signal, and electric sensor is aqueous for obtaining
Rate signal, the twin crystal ultrasonic transducer use the same side structure of transceiver, are installed in horizontal test duct bottom and protect
The angle for demonstrate,proving ultrasonic wave acoustic beam direction and flow direction is θ；The electric sensor is embedded in survey by four circular metal electrodes
Inner-walls of duct composition is tried, is installed on simultaneously in test pipeline with ultrasonic transducer, measuring method comprises the following steps：
1) the moisture content signal H (t) of electric sensor, t ∈ (0, T) and sonac doppler shifted signal are gathered
fd(t), t ∈ (0, T), wherein T are the sampling time；
2) the moisture content average in the sampling time is calculatedBy thHArea is carried out as the convection body of threshold value containing rate
Domain divides：If some time, which inscribes moisture content, is more than thH, then this when the area containing Shuai Weiyedan inscribed moisture content when flowing through electric sensor,
Otherwise this when the area containing Shuai Weiqidan inscribed moisture content when flowing through electric sensor, i.e.,Its
Middle Hnl, HngThe respectively gentle moisture content sequence for playing area in Ye Dan areas；
3) H is utilizednl、HngYe Dan areas moisture content average is calculated respectivelyThe gentle moisture content average for playing area WithWherein Tl, TgRespectively in gentle bullet area of sampling time Nei Yedan area
The time of experience；WillWithSecond zone division is carried out as the convection body of threshold value containing rate：If certain moment moisture content is less thanThen the moment be Qi Dan areas by electric sensor, if certain moment moisture content is more thanAnd it is less thanThen the moment is
Mixing passes through electric sensor, is otherwise Ye Dan areas by electric sensor, i.e.,
Thus T is carved at the beginning of Ye Dan areas being obtained respectively1, the stop timing T of mixed zone2, Qi Dan carve T at the beginning of area3
And the stop timing in Qi Dan areas, i.e., T is carved at the beginning of next Ye Dan areas4；
4) empirical mode decomposition is utilized, high frequency denoising is carried out to ultrasonic Doppler frequency shift signal：Based on empirical modal
The method of decomposition, by ultrasonic Doppler frequency shift signal fd(t), t ∈ (0, T) are decomposed into some intrinsic mode function IMF step by stepj
(t), j=1,2 ..., n and trend function rn(t) sum：Wherein n obtains intrinsic for decomposition
Mode function number, each intrinsic mode function IMF is calculated using cross-correlation methodj(t), j=1,2 ..., n and former Doppler frequency
The coefficient correlation of shifting signal, the coefficient correlation before removal in m levels with former doppler shifted signal are less than threshold value thccHigh frequency it is intrinsic
Mode function component；The general values of m are 3-4, thccGeneral value is 0.2-0.3；By in preceding m levels with former doppler shifted signal
Coefficient correlation be more than or equal to thccIntrinsic mode function, remaining n-m levels intrinsic mode function and trend function rn
(t) sum up, be reassembled into new pending signal fd'(t),t∈(0,T)；
5) method of empirical mode decomposition is reused by signal fd' (t), t ∈ (0, T) are decomposed into some intrinsic mode letters
Number IMFi(t), i=1,2 ..., N and trend term function rN(t) sum, i.e.,Wherein N is decomposition
Obtained intrinsic mode function number；4 grades of intrinsic mode function IMF before selectioni(t), i=1,2,3,4 is as principal component；
6) Short Time Fourier Transform is carried out to principal component and obtains its time-frequency spectrum, by dividing with electricity moisture content combined signal
Analysis, determine the structure flow velocity for the fluid that principal component reflects respectively：First order intrinsic mode function IMF1(t) for most high frequency into
Point, the spread speed of liquid bullet in reflection slug flow；Second level intrinsic mode function IMF2(t) basic covering liquid bullet area is covered, and
First order intrinsic mode function IMF1(t) mean flow rate in Ye Dan areas is reflected together；The third level and fourth stage intrinsic mode function
IMF3(t)&IMF4(t) liquid film area is appeared in, reflection liquid film area inner fluid speed related to drop entraimnent；
7) Fast Fourier Transform (FFT) is carried out to first order intrinsic mode function component and calculates liquid bullet portion i.e. mixed zone time model
Enclose interior Doppler's average frequency shift：To the first order and second level intrinsic mode function component plus and enter
Row Fast Fourier Transform (FFT) simultaneously calculates Doppler's average frequency shift in Ye Dan areas time range
To the third level and fourth stage intrinsic mode function component plus and carry out Fast Fourier Transform (FFT) and calculate in liquid film time range
Doppler's average frequency shiftWherein fd1, fd2, fd3Respectively IMF1(t), IMF1(t)+
IMF2(t), IMF3(t)+IMF4(t) the ultrasonic Doppler frequency displacement under frequency corresponding to, namely different scale, Sd1(fd1), Sd2
(fd2), Sd3(fd3) it is respectively its corresponding energy spectral intensity；
8) according to Doppler effect general principle, the structure flow velocity of slug flow is calculated：The spread speed of wherein liquid bullet is：The average speed of liquid bullet is：The mean flow rate in liquid film area is：Its
Middle f0For the driving frequency of ultrasonic reflections probe, θ is the angle of ultrasonic wave acoustic beam direction and horizontal direction, and c is sound in fluid
Speed.
The present invention substantive distinguishing features be：The moisture content fluctuation signal of Gas-Liquid Slug Flow is obtained using electric sensor, by
Acted in strong reflection of the gas phase to ultrasound, the how general of Gas-Liquid Slug Flow is obtained using homonymy transceiver ultrasonic Doppler sensor
Strangle frequency shift signal.Due to the obvious gas bullet of flow velocity difference in slug flow and the intermittent appearance of liquid bullet, moisture content and flow velocity are at any time
Between fluctuate it is violent.In addition the presence of fluid velocity profile and the distribution containing rate so that doppler shifted signal is that have on diverse location
There is the superposition of scattering object different in flow rate to ultrasonication, be a kind of superposed signal of multi-frequency fluctuation.Therefore, using based on warp
The signal processing method of mode decomposition is tested, Doppler signal is decomposed into some intrinsic mode functions, it is true using cross correlation algorithm
Surely reflect the principal component of signal most significant feature, and Short Time Fourier Transform analysis is carried out to principal component, with reference to moisture content to bullet
The reflection of shape stream intermittent nature, finally realizes the measurement of slug flow structure flow velocity.Beneficial effects of the present invention and advantage are as follows：
, will not any disturbance of convection body generation 1. this method is non-disturbance formula measurement means；
2. electric sensor and the box-like measurement of ultrasonic Doppler sensor group can obtain fluid flow process more fully
Description；
3. the measurement of the structure flow velocity of fluid is realized by signal processing technology and conjoint analysis method, it is simple and easy；
4. measurement is convenient, speed is fast, and cost is low.
Brief description of the drawings
The following drawings describes the embodiment selected by the present invention then, is exemplary diagram and non exhaustive or restricted, wherein：
Ultrasonic Doppler sensor construction schematic diagram in the measuring method of Fig. 1 present invention；
Conductance ring sensor structure schematic diagram in the measuring method of Fig. 2 present invention；
Slug flow cellular construction schematic diagram in Fig. 3 measuring methods of the present invention；
Empirical mode decomposition flow chart in the measuring method of Fig. 4 present invention；
The measuring method of Fig. 5 present invention is hit by a bullet the calculation procedure of shape flow structure flow velocity.
Embodiment
Embodiments of the invention are described in detail with reference to specification figure.
Fig. 1 is the structural representation of continuous wave ultrasound doppler sensor in measuring method of the invention.Patent of the present invention
Ultrasonic Doppler probe used uses the twin crystal ultrasonic transducer of transceiver, and its inside includes a transmitting piezoelectric ceramic crystalline substance
A piece 3a and reception piezoelectric ceramic wafer 3b, is respectively attached on acoustic-electric coupling material 3c and 3d.Acoustic-electric coupling material is direct
Contacted with fluid, and with angle theta between horizontal pipe 10Installation, protects the direction of flow 0 of ultrasonic beam path and two phase flow 2
Hold angle theta.Sound insulating material 4, which is added, between acoustic-electric the coupling material 3c and 3d is produced with preventing from launching and receiving between sound wave
Interference.The twin crystal ultrasonic transducer is installed on horizontal pipe bottom.Transmitting piezoelectric ceramic chip 3a launches ultrasonic wave, sound wave
Propagate in fluid 2, received after receiving discrete phase reflection and scattering in measurement space 5 by reception piezoelectric ceramic wafer 3b.Connect
The flow rate information of fluid in the frequency difference reflected measurement space 5 to quiet down between ripple and transmitting sound wave.
Fig. 2 is the structural representation of conductance ring sensor in measuring method of the invention.Electricity used in patent of the present invention passes
Sensor is embedded in inner-walls of duct 0 by four circular metal electrodes (1,2,3,4) and formed, and wherein electrode 1 and electrode 4 are excitation electricity
Extremely right, electrode 2 and electrode 3 are measuring electrode pair.By injecting constant square-wave excitation current into electrode 1 and connecing electrode 4
Ground, stable electricity sensitivity field can be formed among electrode 1 and 4.When fluid stream crosses sensitivity field, medium contains rate and changes in distribution
When, the electrical potential difference between electrode 2 and electrode 3 is changed, and measurement of the fluid containing rate can be realized by measuring the electrical potential difference.
Fig. 3 is slug flow cellular construction schematic diagram in measuring method of the invention.The Gas-Liquid Slug Flow cellular construction bag
Kuo Yedan areas 2 are gentle to play area 3, the turbulence intensity of fluid and the height in velocity ratio Qi Dan areas 3 in Qie Yedan areas 2.Due to Ye Dan areas
The liquid to be come off from previous liquid bullet is constantly picked up on head, in the front end of liquid bullet when the liquid of high speed merges with the liquid of low speed
The vortex of high speed is formed, for a large amount of discrete bubble distributions among liquid phase, this part is mixed zone 1.In the afterbody liquid of liquid bullet
Because Action of Gravity Field constantly returns liquid film area 4, liquid undergoes faster moderating process in this stage.In the front end of gas bullet, gas
The fluctuation of liquid interface is stronger, causes drop to carry secretly, and over time, flow of fluid is gradually steady, and approximate wave flow delays
Slow flow.It is T to be carved at the beginning of the slug flow cellular construction Zhong Yedan areas 21, the stop timing of mixed zone 1 is T2, Qi Dan areas 3
At the beginning of carve be T3And the stop timing (being carved at the beginning of next Ye Dan areas) in Qi Dan areas 3 is T4.The slug flow unit knot
The spread speed of liquid bullet is V in structureT, the average speed in Ye Dan areas 2 is VS, the mean flow rate in liquid film area 4 is Vf。
Fig. 4 is empirical mode decomposition flow chart in measuring method of the invention.Empirical mode decomposition is a kind of adaptive
Time-Frequency Analysis Method, the fluctuation of different scale present in signal x (t) is separated step by step by the process of screening, produces a system
Intrinsic mode functions (IMF) of the row with different scale, until remaining value sequence rn(t) stop decomposing for monotonic function.It is wherein every
Individual IMF needs to meet two primary conditions：1) quantity (including maximum point and minimum point) and zero crossing of signal extreme point
Quantity it is equal, or at most differ 1；2) signal is put at any time, the coenvelope line and local pole that local maximum determines
The lower envelope line average that small value point determines is zero, and signal is on time shaft Local Symmetric.Condition described above is to screen every time
The stop condition of journey.
Fig. 5 is the calculation procedure flow chart that present invention ultrasound obtains slug flow structure flow velocity with electricity combination sensor.Under
By taking air-water two phase flow as an example, electricity of the invention, ultrasound data conjoint analysis method obtain the calculating of slug flow structure flow velocity in face
Step is as follows：
Step 1：Gather the moisture content signal H (t) of electric sensor, t ∈ (0, T) and sonac Doppler frequency shift
Signal fd(t), t ∈ (0, T), wherein T are the sampling time；
Step 2：Region division is carried out to the fluid of Gas-Liquid Slug Flow according to moisture content signal.
1) the moisture content average in the sampling time is calculatedBy thHEnter as the convection body of threshold value containing rate
Region division of row：If some time, which inscribes moisture content, is more than thH, then this when the area containing Shuai Weiyedan inscribed flow through electric sensor
When moisture content, otherwise this when the area containing Shuai Weiqidan inscribed moisture content when flowing through electric sensor, i.e.,
Wherein Hnl, HngThe respectively gentle moisture content sequence for playing area in Ye Dan areas；
2) H is utilizednl、HngYe Dan areas moisture content average is calculated respectivelyThe gentle moisture content average for playing area WithWherein Tl, TgRespectively in gentle bullet area of sampling time Nei Yedan area
The time of experience.WillWithSecond zone division is carried out as the convection body of threshold value containing rate：If certain moment moisture content is less thanThen the moment be Qi Dan areas by electric sensor, if certain moment moisture content is more thanAnd it is less thanThen the moment is
Mixing passes through electric sensor, is otherwise Ye Dan areas by electric sensor, i.e.,
Thus T is carved at the beginning of Ye Dan areas being obtained respectively1, the stop timing T of mixed zone2, Qi Dan carve T at the beginning of area3
And the stop timing in Qi Dan areas (carves) T at the beginning of next Ye Dan areas4；
Step 3：Method based on empirical mode decomposition is decomposed to doppler shifted signal, and extracts the knot of slug flow
Structure flow velocity.
1) to doppler shifted signal fd(t), t ∈ (0, T) denoising.Generally, included in doppler shifted signal
The composition of high-frequency noise, has a strong impact on analysis precision, it is therefore desirable to carries out denoising.First with the method for empirical mode decomposition,
By ultrasonic Doppler frequency shift signal fd(t), t ∈ (0, T) are decomposed into some intrinsic mode function IMF step by stepj(t), j=1,
2 ..., n and trend function rn(t) sum：
Wherein n is intrinsic mode function number.It is worth noting that, the essence of empirical mode decomposition is screening process, sieve
The end condition of choosing, i.e., each IMF need to meet that two primary conditions are difficult to meet, generally require and restrain quasi- group according to Cauchy,
Screening is terminated by limiting the standard deviation SD between adjacent decomposition result, i.e.,：
Wherein, h1,k-1, h1,kIt is that continuous two decomposition result sequences, SD typically take in the range of 0.2-0.3 in screening process
Value, and its selection can influence the number of decomposited intrinsic mode function.Each intrinsic mode is calculated using cross-correlation method
The coefficient correlation of function and former doppler shifted signal, coefficient correlation is bigger, then shows that the intrinsic mode function more can embody letter
Number most significant feature.Therefore correlation coefficient threshold th is selected according to actual high-frequency noise situationcc, m levels high frequency is intrinsic before selection
Mode function component is judged：If the coefficient correlation of preceding m levels high frequency intrinsic mode function component and former doppler shifted signal
Less than thcc, then it is chosen to remove, otherwise retains.Generally, high-frequency noise is next because frequency highest is decomposited at first, and with
The coefficient correlation of former doppler shifted signal is smaller, therefore the general values of m are 3-4, thccGeneral value is 0.2-0.3.Then will
Coefficient correlation in preceding m levels with former doppler shifted signal is more than or equal to thccIntrinsic mode function, remaining n-m levels sheet
Levy mode function and trend function rn(t) sum up, be reassembled into new pending signal fd'(t),t∈(0,T)；
2) by new pending signal fd' (t), t ∈ (0, T) carry out secondary empirical mode decomposition, then signal can represent
For some intrinsic mode function IMFi(t), i=1,2 ..., N and trend function rN(t) sum：
Intrinsic mode function number when wherein N is twice decomposition.In each IMFi(t) included in be signal from high to low
Different frequency segment components, m- scale feature composition when what each IMF was represented is different in primary signal.Due to Empirical Mode
State decomposition method can be described as principal component analytical method again, it is generally the case that the prime intrinsic mode function point that twice decomposition obtains
Amount has often concentrated most notable, most important information in signal.Therefore 4 grades of intrinsic mode function IMF before selection determinesj(t),j
=1,2,3,4 are used as principal component；
3) time frequency analysis is carried out to principal component using the method for Short Time Fourier Transform, believed with reference in step 2 by moisture content
The division result of number convection body, determine the structure flow velocity for the fluid that principal component reflects respectively.By electricity, the connection of ultrasound information
Analysis is closed, determines first order intrinsic mode function IMF1(t) it is most radio-frequency component, appears in the head in Ye Dan areas, reflection plays shape
The spread speed of liquid bullet in stream；Second level intrinsic mode function IMF2(t) basic covering liquid bullet area, and first order eigen mode are covered
State function IMF1(t) mean flow rate in Ye Dan areas is reflected together；The third level and fourth stage intrinsic mode function IMF3(t)&IMF4
(t) liquid film area is appeared in, reflection liquid film area inner fluid speed related to drop entraimnent；
4) when Fast Fourier Transform (FFT) is carried out to first order intrinsic mode function component and calculating liquid bullet portion (mixed zone)
Between in the range of Doppler's average frequency shift：To the first order and second level intrinsic mode function point
Amount plus and carry out Fast Fourier Transform (FFT) and calculate Doppler's average frequency shift in Ye Dan areas time rangeTo the third level and fourth stage intrinsic mode function component plus and carry out fast Fourier
Convert and calculate Doppler's average frequency shift in liquid film time rangeWherein fd1, fd2,
fd3RespectivelyIMF1(t)+IMF2(t), IMF3(t)+IMF4(t) how general the ultrasound under respective frequencies, i.e. different scale is
Strangle frequency displacement, Sd1 (fd1), Sd2(fd2), Sd3(fd3) it is respectively its corresponding energy spectral intensity, T1, T2, T3, T4Obtained by step 2
.
5) according to the general principle of Doppler effect, the structure flow velocity of slug flow is calculated：The spread speed of wherein liquid bullet is：The average speed (while being total apparent velocity of slug flow) of liquid bullet is：Liquid film area
Mean flow rate be：Wherein f0For the driving frequency of ultrasonic reflections probe, θ is ultrasonic wave acoustic beam side
To the angle with horizontal direction, c is the velocity of sound in fluid.
Claims (1)
- A kind of 1. Gas-Liquid Slug Flow structure flow velocity acoustic-electric bimodal measuring method, using twin crystal ultrasonic transducer and electric sensor Realize, twin crystal ultrasonic transducer is used to obtain two phase flow ultrasonic Doppler frequency shift signal, and electric sensor is used to obtain moisture content Signal, the twin crystal ultrasonic transducer use the same side structure of transceiver, are installed in horizontal test duct bottom and ensure The angle of ultrasonic wave acoustic beam direction and flow direction is θ；The electric sensor is embedded in test by four circular metal electrodes Inner-walls of duct forms, and is installed on simultaneously in test pipeline with ultrasonic transducer, measuring method comprises the following steps：1) the moisture content signal H (t) of electric sensor, t ∈ (0, T) and sonac doppler shifted signal f are gatheredd (t), t ∈ (0, T), wherein T are the sampling time；2) the moisture content average in the sampling time is calculatedBy thHRegion is carried out as the convection body of threshold value containing rate to draw Point：If some time, which inscribes moisture content, is more than thH, then this when the area containing Shuai Weiyedan inscribed moisture content when flowing through electric sensor, otherwise This when the area containing Shuai Weiqidan inscribed moisture content when flowing through electric sensor, i.e.,Its Middle Hnl, HngThe respectively gentle moisture content sequence for playing area in Ye Dan areas；3) H is utilizednl、HngYe Dan areas moisture content average is calculated respectivelyThe gentle moisture content average for playing area WithWherein Tl, TgRespectively in gentle bullet area of sampling time Nei Yedan area The time of experience；WillWithSecond zone division is carried out as the convection body of threshold value containing rate：If certain moment moisture content is less thanThen the moment be Qi Dan areas by electric sensor, if certain moment moisture content is more thanAnd it is less thanThen the moment is Mixing passes through electric sensor, is otherwise Ye Dan areas by electric sensor, i.e.,Thus T is carved at the beginning of Ye Dan areas being obtained respectively1, the stop timing T of mixed zone2, Qi Dan carve T at the beginning of area3And The stop timing in Qi Dan areas, i.e., T is carved at the beginning of next Ye Dan areas4；4) empirical mode decomposition is utilized, high frequency denoising is carried out to ultrasonic Doppler frequency shift signal：Based on empirical mode decomposition Method, by ultrasonic Doppler frequency shift signal fd(t), t ∈ (0, T) are decomposed into some intrinsic mode function IMF step by stepj(t), j= 1,2 ..., n and trend function rn(t) sum：Wherein n is to decompose obtained intrinsic mode letter Several numbers, each intrinsic mode function IMF is calculated using cross-correlation methodj(t), j=1,2 ..., n and former doppler shifted signal Coefficient correlation, the coefficient correlation before removal in m levels with former doppler shifted signal is less than threshold value thccThe intrinsic mode letter of high frequency Number component；The general values of m are 3-4, thccGeneral value is 0.2-0.3；Will be related to former doppler shifted signal in preceding m levels Coefficient is more than or equal to thccIntrinsic mode function, remaining n-m levels intrinsic mode function and trend function rn(t) carry out Add and be reassembled into new pending signal f 'd(t),t∈(0,T)；5) method of empirical mode decomposition is reused by signal f 'd(t), t ∈ (0, T) are decomposed into some intrinsic mode functions IMFi(t), i=1,2 ..., N and trend term function rN(t) sum, i.e.,Wherein N is to decompose The intrinsic mode function number arrived；4 grades of intrinsic mode function IMF before selectioni(t), i=1,2,3,4 is as principal component；6) Short Time Fourier Transform is carried out to principal component and obtains its time-frequency spectrum, by being analyzed with electricity moisture content combined signal, Determine the structure flow velocity for the fluid that principal component reflects respectively：First order intrinsic mode function IMF1(t) it is most radio-frequency component, instead Reflect the spread speed of liquid bullet in slug flow；Second level intrinsic mode function IMF2(t) basic covering liquid bullet area, and the first order are covered Intrinsic mode function IMF1(t) mean flow rate in Ye Dan areas is reflected together；The third level and fourth stage intrinsic mode function IMF3(t)& IMF4(t) liquid film area is appeared in, reflection liquid film area inner fluid speed related to drop entraimnent；7) Fast Fourier Transform (FFT) is carried out to first order intrinsic mode function component and calculates liquid bullet portion i.e. in the time range of mixed zone Doppler's average frequency shift：To the first order and second level intrinsic mode function component plus and carry out fast Fast Fourier transformation simultaneously calculates Doppler's average frequency shift in Ye Dan areas time rangeTo Three-level and fourth stage intrinsic mode function component plus and carry out Fast Fourier Transform (FFT) and calculate more in liquid film time range General Le average frequency shiftWherein fd1, fd2, fd3Respectively IMF1(t), IMF1(t)+IMF2 (t), IMF3(t)+IMF4(t) the ultrasonic Doppler frequency displacement under frequency corresponding to, namely different scale, Sd1(fd1), Sd2(fd2), Sd3(fd3) it is respectively its corresponding energy spectral intensity；8) according to Doppler effect general principle, the structure flow velocity of slug flow is calculated：The spread speed of wherein liquid bullet is：The average speed of liquid bullet is：The mean flow rate in liquid film area is：Its Middle f0For the driving frequency of ultrasonic reflections probe, θ is the angle of ultrasonic wave acoustic beam direction and horizontal direction, and c is sound in fluid Speed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201710638226.8A CN107389974B (en) | 2017-07-31 | 2017-07-31 | Gas-Liquid Slug Flow structure flow velocity acoustic-electric bimodal measurement method |
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