CN102213606A - Mirror image flow detection method and virtual flowmeter - Google Patents

Abstract

The invention belongs to the technical field of fluid flow, and particularly relates to a mirror image flow detection method, which comprises the following steps of: measuring pressure at front and rear ends of a pipeline and the flow of fluid in the pipeline; performing self-learning of flowability characteristic coefficients of the pipeline; calculating a mirror image flow value of the fluid in the pipeline according to the obtained flowability characteristic coefficient domain and the pressure at the front and rear ends of the pipeline; and when determining that the flowability characteristic of a specified pipe section is not changed suddenly and that a flow value of the actual fluid in the monitored pipeline deviates and even is lost, selecting the mirror image flow value as a result to be outputted. The invention also discloses a virtual flowmeter, which comprises at least two pressure sensors, a self-learning module and a virtual flowmeter module. The virtual flowmeter realizes the embedding of a mirror image algorithm function, and achieves the redundant effect that the mirror image flow value becomes a shadow behind the fluid flow value gradually by the self-learning.

Description

Mirror image flow rate testing methods and virtual flowmeter

Technical field

Fluid metering technical field of the present invention is specifically related to a kind of mirror image flow rate testing methods and virtual flowmeter.

Background technology

Along with development of technology, the test format kind of flow is numerous.Commonly used have (throttling) differential pressure flowmeter, as orifice plate, nozzle etc.; Volumeter is as elliptic gear, rotary-piston type etc.; Velocity flowmeter is as vane type, plug-in type etc.; Vibratory flowmeter is as vortex, precession etc.; Also have electromagnetic flowmeter, ultrasonic flow meter, mass flowmeter.Even also have pressure-type flowmeter, sound type flowmeter or the like.

For convenient difference, above-mentioned flowmeter is referred to as " the equipment flowmeter " that is made of hardware device, measurement result is output as the fluid flow value.

Why of a great variety the equipment flowmeter is, and its main cause is that the physics of fluid, chemical characteristic are very numerous and diverse, the operating mode that every kind of equipment flowmeter only can corresponding one or more adaptations.As gas, liquid, gas-solid mixture are arranged from the fluid media (medium) branch; From the flow velocity branch high speed, low speed, wriggling are arranged; What also have contains particle and will wear and tear, contain that grease will bond, extraordinary chemical substance can solidify; The fluid conduction that has or insulation or the like.

Before the designing apparatus flowmeter, all must analyze physics, chemical characteristic and the working environment of anticipation cutout body, could correctly select the flowmeter test format that meets operating mode for use.Yet, when the physics of fluid, the variation of chemical characteristic generation matter, use that back equipment flowmeter detecting element is worn perhaps for a long time, to change appear in bonding etc. self serviceability, must cause the flow detection value skew to occur, even can't operate as normal.

As electromagnetic flowmeter be direct measuring channel inner fluid speed V as flow Q beasurement base, in magnetic field, produce the principle of induced potential during cutting magnetic line movement at its two ends by means of conductor.Owing to can only measure conducting liquid, therefore for the very low liquid of the liquid that contains a large amount of bubbles or conductivity energy measurement not.By way of example, blast furnace cooling stave uses soft water or pure water as heat eliminating medium usually, because that the largest benefit of electromagnetic flowmeter is without hindrance damage, precision is high, recommends usually to adopt as far as possible.Before the design process conductivity period parameters study and judge with most of practical application in, can both satisfy the technical requirement of electromagnetic flowmeter.But need dosing in order to improve the water quality that runs down sometimes, the excessive conductivity that causes of dose delivery is low; Or the cooling wall local overheating causes a large amount of vapor bubbles to sneak in the chilled water, all makes electromagnetic flowmeter temporarily lose the flow detection function.

Summary of the invention

In view of this, in order to address the above problem, the invention discloses a kind of mirror image flow rate testing methods, in the engineering practical application, when the equipment flowmeter is influenced by the external world or internal factor, after judgement flow detection value deviation occurs even loses suddenly, can utilize the dynamic flow characteristic information of collecting in advance, extrapolate a flow substitution value according to the situation of change of pressure differential, continue to keep the problem of flow detection function.

The object of the present invention is achieved like this: the mirror image flow rate testing methods comprises the steps:

1) measures the pressure and the pipeline inner fluid flow of pipeline rear and front end; According to following formula, self study obtains the mobile characteristic coefficient territory θ of pipeline:

$Q=\mathrm{\θ}\left[\begin{array}{c}A\\ B\\ C\\ D\\ \·\·\·\end{array}\right]\underset{i=0}{\overset{m}{\mathrm{\Σ}}}{(\mathrm{\ΔP}-\mathrm{\ΔH})}^{\frac{i}{2}};$

In the following formula, Q is a pipeline inner fluid flow value; I is the value number; M is the number of explanatory variable;

Be mobile characteristic coefficient territory, wherein comprise specify pipe characteristic (1, d, ε) with characteristic of fluid (ρ, η); Δ P-Δ H is for specifying the pressure differential of pipeline rear and front end;

2), obtain pipeline inner fluid mirror image flow value q ' by following formula according to the pressure of mobile characteristic coefficient territory with the pipeline rear and front end that records:

$q\′=\mathrm{\θ}\left[\begin{array}{c}A\\ B\\ C\\ D\\ \·\·\·\end{array}\right]\underset{i=0}{\overset{m}{\mathrm{\Σ}}}{(\mathrm{\ΔP}-\mathrm{\ΔH})}^{\frac{i}{2}};$

Further, also comprise the steps:

3) when the pipeline inner fluid flow value generation deviation that records, the big value during the pipeline inner fluid flow value that records and mirror image flow value compared is exported as flow value;

Repeated execution of steps 1,2,3), dynamically obtains pipeline inner fluid flow value and mirror image flow value, and constitute redundancy relationship;

Further, in the step 3), judge by following steps whether the pipeline inner fluid flow value that records deviation takes place:

When the mirror image flow value q ' of step 3) gained more than or equal to 1.06 times of pipeline inner fluid flow value Q, and Δ P-Δ H variation range is in 10%, and pipeline section upstream section gross head pressure P _BeforeAnd pipeline section downstream section gross head pressure P _AfterVariation range also in 10%, is then judged pipeline inner fluid flow value generation deviation.

The present invention also discloses a kind of virtual flowmeter, comprising:

At least two pressure transducers are used for the pressure of measuring channel rear and front end;

Self-learning module, the pressure of receiving pipeline rear and front end and pipeline inner fluid flow value data, according to following formula, self study obtains the mobile characteristic coefficient of pipeline territory:

$Q=\mathrm{\θ}\left[\begin{array}{c}A\\ B\\ C\\ D\\ \·\·\·\end{array}\right]\underset{i=0}{\overset{m}{\mathrm{\Σ}}}{(\mathrm{\ΔP}-\mathrm{\ΔH})}^{\frac{i}{2}};$

In the following formula, Q is a pipeline inner fluid flow value; I is the value number; M is the number of explanatory variable; Be mobile characteristic coefficient territory, wherein comprise specify pipe characteristic (1, d, ε) with characteristic of fluid (ρ, η); Δ P-Δ H is for specifying the pressure differential of pipeline rear and front end;

Virtual flow computing module is used for being obtained the mirror image flow value q ' of pipeline inner fluid by following formula according to the pressure of mobile characteristic coefficient territory with the pipeline rear and front end that records:

$q\′=\mathrm{\θ}\left[\begin{array}{c}A\\ B\\ C\\ D\\ \·\·\·\end{array}\right]\underset{i=0}{\overset{m}{\mathrm{\Σ}}}{(\mathrm{\ΔP}-\mathrm{\ΔH})}^{\frac{i}{2}};$

In the following formula, i is the value number; M is the number of explanatory variable;

Be mobile characteristic coefficient territory, wherein comprise specify pipe characteristic (1, d, ε) with characteristic of fluid (ρ, η); Δ P-Δ H is for specifying the pressure differential of pipeline rear and front end.

Further, also comprise:

The measured value read module is used for obtaining synchronously the fluid flow value in the pipeline, the force value of rear and front end;

Memory module, the mobile characteristic coefficient territory that is used to store this appointment pipeline;

Further, also comprise:

Output stream value handover module, in order to judge when specifying the mobile feature of pipeline section not occur suddenling change, whether monitored pipeline inner fluid flow value has deviation, if any, then stop self study, the big value during the pipeline inner fluid flow value Q that records and pipeline inner fluid mirror image flow value q ' are compared is exported as the flow results value.

The invention has the beneficial effects as follows: after the number reason tectonic analysis of the present invention to classical channel theory, successfully extend, formed a kind of brand-new, general flow rate calculation method; Embody Δ P-Δ H, Q, θ triadic relation's optimization expression formula, calculates more simply and accurate, verify that calculating is very satisfactory.Its single step algorithm is particularly suitable for Computing.An any type of equipment flowmeter can be forged into the flowmeter that has fluid flow value and mirror image flow value and deposit, can adopt independently embedded controller or directly implant in the equipment flowmeter, even a segment standard product software is provided, be easy to realize.

Be applicable on the various forms of equipment flowmeters.Realize that the mirror image algorithm function embeds, playing the mirror image flow value progressively becomes the fluid flow value redundant effect of shadow behind after by self study.Even foreground equipment flowmeter damages or lost efficacy, the mirror image flow value of looking for the fluid rule still calculates and in time substitutes output on the backstage.

Description of drawings

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is described in further detail below in conjunction with accompanying drawing:

Virtual flowmeter check point is provided with process flow diagram in Fig. 1 fluid circulating system;

Fig. 2 length is provided with process flow diagram apart from virtual flowmeter check point in the induction system;

Corresponding each the flow section in the mobile characteristic coefficient of Fig. 3 territory concern synoptic diagram;

Fig. 4 tests the match relationship degree curve of fluid flow value and mirror image flow value in 1;

Fig. 5 tests the match relationship degree curve of fluid flow value and mirror image flow value in 2;

Fig. 6 tests the match relationship degree curve of fluid flow value and mirror image flow value in 3;

Fig. 7 tests the match relationship degree curve of fluid flow value and mirror image flow value in 4.

Embodiment

Under the normality, pressure differential deltap P-Δ H is the cause that causes fluid to flow along pipeline before and after existing, and the size of corresponding flow Q and fluid-transporting tubing characteristic θ (caliber, length and coefficient of frictional resistance, density, viscosity etc.) have interaction.Δ P-Δ H, Q, θ three connect each other also and condition each other, and constitute the funtcional relationship of expressing each other.As peaceful (Fanning) formula Δ P of model _f=(λ L/d+ ∑ ζ) ρ/2 (4/ π d ²) ²Q ²

Present embodiment provides a kind of mirror image flow rate testing methods and virtual flowmeter, can be according to knowing fluid flow Q and front and back pressure differential deltap P-Δ H, and both fluctuate after the varied sections relation, try to achieve the dynamic flow characteristic coefficient of pipeline by the mode of self study

The territory; Known front and back pressure differential deltap P-Δ H of foundation and the mobile characteristic coefficient that has obtained have been proposed when deviation even unexpected loss detection function appear in the equipment flowmeter Virtual flow q ' and changeable output under the prevailing circumstances are oppositely calculated in the territory, are called full-time territory, continual a kind of virtual flowmeter output stream value based on the mirror image flow rate testing methods.

The mirror image flow rate testing methods comprises the steps:

1) measures the pressure and the pipeline inner fluid flow of pipeline rear and front end; According to following formula, self study obtains the mobile characteristic coefficient territory θ of pipeline:

$Q=\mathrm{\θ}\left[\begin{array}{c}A\\ B\\ C\\ D\\ \·\·\·\end{array}\right]\underset{i=0}{\overset{m}{\mathrm{\Σ}}}{(\mathrm{\ΔP}-\mathrm{\ΔH})}^{\frac{i}{2}};$

In the following formula, Q is a pipeline inner fluid flow value; I is the value number; M is the number of explanatory variable;

Be mobile characteristic coefficient territory, wherein comprise specify pipe characteristic (1, d, ε) with characteristic of fluid (ρ, η); Δ P-Δ H is for specifying the pressure differential of pipeline rear and front end;

2), obtain pipeline inner fluid mirror image flow value q ' by following formula according to the pressure of mobile characteristic coefficient territory with the pipeline rear and front end that records:

$q\′=\mathrm{\θ}\left[\begin{array}{c}A\\ B\\ C\\ D\\ \·\·\·\end{array}\right]\underset{i=0}{\overset{m}{\mathrm{\Σ}}}{(\mathrm{\ΔP}-\mathrm{\ΔH})}^{\frac{i}{2}}.$

Further, also comprise the steps:

3) when the pipeline inner fluid flow value generation deviation that records, the big value during the pipeline inner fluid flow value that records and mirror image flow value compared is exported as flow value;

Repeated execution of steps 1,2,3), dynamically obtains pipeline inner fluid flow value and mirror image flow value, and constitute redundancy relationship.

Further, in the step 3), judge by following steps whether the pipeline inner fluid flow value that records deviation takes place:

When the mirror image flow value q ' of step 3) gained more than or equal to 1.06 times of pipeline inner fluid flow value Q, and Δ P-Δ H variation range is in 10%, and pipeline section upstream section gross head pressure P _BeforeAnd pipeline section downstream section gross head pressure P _AfterVariation range also in 10%, is then judged pipeline inner fluid flow value generation deviation.

The present invention also discloses a kind of virtual flowmeter, comprising:

At least two pressure transducers are used for the pressure of measuring channel rear and front end;

Self-learning module, the pressure of receiving pipeline rear and front end and pipeline inner fluid flow value data, according to following formula, self study obtains the mobile characteristic coefficient of pipeline territory:

$Q=\mathrm{\&theta;}\left[\begin{array}{c}A\\ B\\ C\\ D\\ \&CenterDot;\&CenterDot;\&CenterDot;\end{array}\right]\underset{i=0}{\overset{m}{\mathrm{\&Sigma;}}}{(\mathrm{\&Delta;P}-\mathrm{\&Delta;H})}^{\frac{\mathrm{<figure-callout\; id="2"\; label="i"\; filenames="HDA0000054467250000021.png,HDA0000054467250000032.png"\; state="\{\{state\}\}">i</figure-callout>}}{2}};$

In the following formula, Q is a pipeline inner fluid flow value; I is the value number; M is the number of explanatory variable;

Be mobile characteristic coefficient territory, wherein comprise specify pipe characteristic (1, d, ε) with characteristic of fluid (ρ, η); Δ P-Δ H is for specifying the pressure differential of pipeline rear and front end;

Virtual flow computing module is used for being obtained the mirror image flow value q ' of pipeline inner fluid by following formula according to the pressure of mobile characteristic coefficient territory with the pipeline rear and front end that records:

$q\&prime;=\mathrm{\&theta;}\left[\begin{array}{c}A\\ B\\ C\\ D\\ \&CenterDot;\&CenterDot;\&CenterDot;\end{array}\right]\underset{i=0}{\overset{m}{\mathrm{\&Sigma;}}}{(\mathrm{\&Delta;P}-\mathrm{\&Delta;H})}^{\frac{\mathrm{<figure-callout\; id="2"\; label="i"\; filenames="HDA0000054467250000021.png,HDA0000054467250000032.png"\; state="\{\{state\}\}">i</figure-callout>}}{2}};$

In the following formula, i is the value number; M is the number of explanatory variable;

Be mobile characteristic coefficient territory, wherein comprise specify pipe characteristic (1, d, ε) with characteristic of fluid (ρ, η); Δ P-Δ H is for specifying the pressure differential of pipeline rear and front end.

Further, also comprise:

The measured value read module is used for obtaining synchronously the fluid flow value in the pipeline, the force value of rear and front end;

Memory module, the mobile characteristic coefficient territory that is used to store this appointment pipeline.

Further, also comprise:

Output stream value handover module, in order to judge when specifying the mobile feature of pipeline section not occur suddenling change, whether monitored pipeline inner fluid flow value has deviation, if any, then stop self study, the big value during the pipeline inner fluid flow value Q that records and pipeline inner fluid mirror image flow value q ' are compared is exported as the flow results value.

Fig. 1 is that virtual flowmeter check point is provided with process flow diagram in the fluid circulating system.Be usually used in chilled water and close circulation process, many FLUID TRANSPORTATION pumps 1,2,3,4 are taken turns and are changed jobs, deliver to fluid near the cooling device by water main after, be provided with a loop pipe to distribute each arm cooling confluent; After by arm subsystem being finished cooling, enter endless tube again and compile chilled water, water cycle is used with return main's form.Water main is provided with total tube apparatus flowmeter FT1, and with house steward's top hole pressure PT1 as preceding pressure P _{Preceding 1}By means of the endless tube pressure P T2 on the feedwater endless tube, both as pressure P behind the house steward _{Back 2}Simultaneously also as pressure P before the arm _{Preceding 21}, P _{Preceding 22}, P _{Preceding 23}, P _{Preceding 24}, source pressure is in the corresponding P of top hole pressure PT3 behind the arm _{Back 31}, P _{Back 32}, P _{Back 33}, P _{Back 34}, each arm is provided with a tube apparatus flowmeter FT11, FT12, FT13, FT14.And set hand valve HV1, HV2, HV3, HV4 is used to distribute each arm cooling confluent behind the feedwater endless tube, in case remain unchanged substantially after adjusting to the right place as required, can decrease element as fixing resistance here and take in.

Fig. 2 is that length is provided with process flow diagram apart from virtual flowmeter check point in the induction system.The regional gas transmission pipeline net work that is usually used in combustion medium is for steady pressure generally is provided with control valve M.The zone pipe network may provide the energy to the different user workshop respectively, and each workshop all may be provided with monitoring, therefore can cause upstream and downstream and deposit a plurality of front and back pressure detection.Reasonably collect these pressure informations, can be selectively, optimize and constitute the multiple redundancy new flowmeter, benefit is can also screen the mirror image flow value again, avoids the fluctuation of specifying the mobile feature of pipeline section, and reliability promotes once more.

Below theoretically the method and the virtual flowmeter of present embodiment are inquired into: classical channel theory can be understood as: start with from understanding pipeline section and fluid behaviour, defined characteristic description parameter (1 for this reason, d, λ, ε) wait that (off-line static state (tabling look-up) is differentiated mutual relationship under the flow state → extrapolate pipe flow speed V (flow) for ρ, μ) parameter etc. → try to achieve reynolds number Re with characteristic of fluid.

1. a kind of theory of the virtual flowmeter based on the mirror image flow rate testing methods can be understood as and oppositely derives earlier: from pipe flow speed V (flow) start with → the pass through variable quantity of front and back pressure differential deltap P-Δ H, dynamic discriminant flow state → self study goes out to specify pipeline section in laminar flow, turbulent flow, complete turbulent lower curtate feature, completely newly is defined as mobile characteristic coefficient The territory; 2. forward converts again: according to the mobile characteristic coefficient of the appointment pipeline section that obtains from study

The varied sections of the front and back pressure differential deltap P-Δ H that territory → corresponding learning process is noted, the mobile characteristic coefficient under the different fluidised forms of dynamic call

With

Concrete group in the territory adapts to current flow state → pass through

Converse current mirror image flow value.

Carry out simple concrete the derivation and analysis below respectively:

1, classical channel theory all derive based on following three equilibrium equations:

Fluid is the continuity mass equation in constant caliber: $V=\frac{4Q}{\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="HDA0000054467250000021.png,HDA0000054467250000032.png"\; state="\{\{state\}\}">d</figure-callout>}}^2}...m/s$

Fluid is energy balance-Bernoulli equation in pipeline: $h_f=\frac{p_1-{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="HDA0000054467250000021.png,HDA0000054467250000032.png"\; state="\{\{state\}\}">p</figure-callout>}}_2}{\mathrm{\&rho;}}-g(z_2-z_1)...J/\mathrm{Kg}$

Straight tube frictional resistance h _fAnd concern between the coefficient of frictional resistance λ: $h_f=\mathrm{\&lambda;}\frac{\mathrm{<figure-callout\; id="2"\; label="l\; d\; V"\; filenames="HDA0000054467250000021.png,HDA0000054467250000032.png"\; state="\{\{state\}\}">l</figure-callout>}}{d}\frac{V^{}}{}\frac{{}^2}{2}...J/\mathrm{Kg}$

The definition Reynolds number $\mathrm{Re}=\frac{\mathrm{Vd\&rho;}}{\mathrm{\&eta;}}$

Friction factor λ: λ=64/Re during laminar flow

$h_f=\frac{64}{\mathrm{Re}}\frac{1}{\mathrm{<figure-callout\; id="2"\; label="d\; V"\; filenames="HDA0000054467250000021.png,HDA0000054467250000032.png"\; state="\{\{state\}\}">d</figure-callout>}}\frac{V^{}}{}\frac{{}^2}{2}$

Friction factor λ during turbulent flow:

$\frac{1}{\sqrt{\mathrm{\&lambda;}}}=1.74-2\log (\frac{2\mathrm{\&epsiv;}}{d}+\frac{18.7}{\mathrm{Re}\sqrt{\mathrm{\&lambda;}}})\frac{1}{\sqrt{\mathrm{\&lambda;}}}=1.74-2\log (\frac{2\mathrm{\&epsiv;}}{d}+\frac{18.7}{\mathrm{Re}\sqrt{\mathrm{\&lambda;}}})$

Or $\mathrm{\&lambda;}=0.1{(\frac{\mathrm{\&epsiv;}}{d}+\frac{68}{\mathrm{Re}})}^{0.23}$

Or $\mathrm{\&lambda;}=\frac{0.3164}{{\mathrm{Re}}^{0.25}}$

Or $\mathrm{\&lambda;}=0.0056+\frac{0.500}{{\mathrm{Re}}^{0.32}}$ Deng.

Because λ is one during except laminar flow

Bai Laxiusi formula with smooth pipe

Outside fairly simple, all the other each formula are more complicated all, uses the comparison inconvenience.Poor for fear of examination in engineering calculation, generally be the λ that will measure by experiment and Re with

Relation, with

Being parameter, is ordinate with λ, is horizontal ordinate with Re, marks and draws on log-log paper.This figure is called not Di's friction factor figure.

2, understand again after, press the demand rewriting relational expression of new theory:

Self study for convenience is to frictional resistance h _fAnd concern between the coefficient of frictional resistance λ:

Formula

With Expand and be rewritten into:

h _f---pipe characteristic frictional resistance;

---mobile characteristic coefficient territory, comprise specify pipe characteristic (1, d, ε) with characteristic of fluid (ρ, η).Describe characteristic variations slowly, conveniently be provided with before and after pressure differential deltap P-Δ H detect, fully the corresponding device flowmeter, specify have sufficient length, chosen in advance do not have the mobile feature of leaking pipeline section.Even some creeps occur, by the self study correction that upgraded in time;

Q---pipeline inner fluid flow value;

I---value number

The number of m---explanatory variable.

3, the analysis in mobile characteristic coefficient territory, obtain and use:

1) relational expression

In, Q can obtain by equipment flowmeter on the pipeline of installing.

2) also have drag losses to show as the reduction of fluid potential energy,

$\frac{{\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="HDA0000054467250000032.png,HDA0000054467250000042.png"\; state="\{\{state\}\}">p</figure-callout>}}_1}{\mathrm{\&rho;}}+\frac{{\mathrm{<figure-callout\; id="1"\; label="u"\; filenames="HDA0000054467250000032.png,HDA0000054467250000042.png"\; state="\{\{state\}\}">u</figure-callout>}}_1^2}{2}+h_e=\frac{{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="HDA0000054467250000021.png,HDA0000054467250000032.png"\; state="\{\{state\}\}">p</figure-callout>}}_2}{\mathrm{\&rho;}}+\frac{{\mathrm{<figure-callout\; id="2"\; label="u"\; filenames="HDA0000054467250000021.png,HDA0000054467250000032.png"\; state="\{\{state\}\}">u</figure-callout>}}_2^2}{2}+h_f$

h _e(nothing adds mechanical energy), u ₁=u ₂(isometrical)

$h_f=\frac{p_1-{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="HDA0000054467250000021.png,HDA0000054467250000032.png"\; state="\{\{state\}\}">p</figure-callout>}}_2}{\mathrm{\&rho;}}=(\frac{{\mathrm{\&rho;}}_1}{\mathrm{\&rho;}}+g{z}_1)-(\frac{{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="HDA0000054467250000021.png,HDA0000054467250000032.png"\; state="\{\{state\}\}">p</figure-callout>}}_2}{\mathrm{\&rho;}}+g{z}_2)$

No matter formula for common pipeline, is straight tube resistance or shock resistance as can be known thus, no matter also be laminar flow or turbulent flow, drag losses all mainly shows as the reduction of fluid potential energy, both

This formula shows to have only horizontal pipe (z simultaneously ₁=z ₂), could with Replace

Express h _fIn engineering, can directly be write as:

Δ P-Δ H=h _f=(P _Before-P _After)-Δ H

Obtain by frictional resistance h _fPressure differential deltap P-Δ H before and after the drag losses of characteristic decision equals.

Δ P-Δ H---be converted into the front and back pressure difference detection value after suitable level is specified pipeline section;

Δ P---be pipeline section upstream and downstream two section gross head pressure differential J/m ³Or Pa; Can obtain by pressure detection before and after being provided with.

Δ H---be that static lift is actual water level difference of elevation J/m ³Or Pa; Can obtain by measurement.

P _Before---be pipeline section upstream section gross head pressure J/m ³Or Pa.

P _After---be pipeline section downstream section gross head pressure J/m ³Or Pa.

Therefore Also can be characterized by the general expression formula of mirror image flow value mirror image algorithm:

$q\&prime;=\mathrm{\&theta;}\left[\begin{array}{c}A\\ B\\ C\\ D\\ \&CenterDot;\&CenterDot;\&CenterDot;\end{array}\right]\underset{i=0}{\overset{m}{\mathrm{\&Sigma;}}}{(\mathrm{\&Delta;P}-\mathrm{\&Delta;H})}^{\frac{\mathrm{<figure-callout\; id="2"\; label="i"\; filenames="HDA0000054467250000021.png,HDA0000054467250000032.png"\; state="\{\{state\}\}">i</figure-callout>}}{2}}.$

So far by calculating, can obtain different m value current downflow characteristic coefficients, i.e. A, B, C, D...... (i+1 altogether).

3) by formula:

Draw:

Promptly

According to long-term experiment with draw in conjunction with experience

With

Find out λ and Q

With

Power is relevant, so

Promptly

According to mathematical principle,, relational expression can directly be write as when adopting the theory that higher equation once can the low power characteristic curve of fine match:

Simply be interpreted as according to number reason tectonic analysis processes classical channel theory: certain stage pipeline equivalent length L, internal diameter of the pipeline d, when the real-time roughness ε variable quantity of pipeline is very little, and the density p of fluid, when the viscosities il variable quantity is also very little; When Δ P-Δ H fluctuation in the section of working separately, flow Q with

Present cube relation, and follow by mobile characteristic coefficient territory express Δ P-Δ H, Q, θ three connects also conditioning each other relation each other, constitutes the function of expression each other.

Summary is said, concrete foundation

Relational expression, self study go out to specify pipeline section in laminar flow, turbulent flow, complete turbulent lower curtate feature, completely newly are defined as mobile characteristic coefficient

The composition parameter in territory has been realized a kind of reverse derivation function of the virtual flowmeter based on the mirror image flow rate testing methods.

4, next be that forward is derived:

Because a variety of causes causes flow detection deviation to occur, even lose the flow detection function suddenly when the equipment flowmeter, through multidata comparison, judgement, fluid flow value Q and mirror image flow value q ' can switch output.Practical manner:

Rely on self study to obtain A, B, the mobile characteristic coefficient of C, D, and back and forth upgrade and improve adaptive faculty.Virtual flow is calculated according to detected Δ P-Δ H parameter backstage again in the foreground when obtaining flow measuring apparatus Q continuously

After, compare.When

I: if q ' 〉=1.06Q; (descending appears in the Q value)

II: and this Δ P-Δ H variation range is in 10%; (at this moment

Pressure differential is in basic normal variation zone and fluctuation is lower than the fluctuations in discharge amount)

III: judge P again _BeforeWhether variation range is in 10%; (showing that big adjustment does not take place in the downstream shock resistance)

IV:P _AfterWhether variation range is in 10%.(showing that big adjustment does not take place in the upstream shock resistance)

If four conditions satisfy, explanation is after having got rid of all external interference, if descending significantly also appears in fluid flow value Q, should think that the equipment flowmeter is disturbed by a variety of causes to cause Q deviation to occur even loses suddenly, then the big value compared with Q of q ' is selected as the output stream value.And stop the mobile characteristic coefficient of self study, with P _BeforeAnd P _AfterMake mean value calculation.

As condition I: if q ' 〉=1.06Q is disengaged, promptly during q '＜1.04Q, and

With Return to the output device flowmeter and detect the Q state of value.

5, divide way about the self study under the corresponding laminar flow in the mobile characteristic coefficient of θ territory, turbulent flow, the turbulent fully work section:

Mobile characteristic coefficient territory comprise specify pipe characteristic (1, d, ε) with characteristic of fluid (ρ, η).Wherein obtain coefficient A, B, C, D numerical expression by self study, they have comprised all mobile features of specific pipeline section.When splitting into laminar flow, Aa, Ba, Ca, Da; During turbulent flow, Ab, Bb, Cb, Db; When turbulent fully, Ac, Bc, Cc, Dc; The flow section packets constitutes.

See that in conjunction with classical channel theory pipe characteristic is with Reynolds number Therefore constant interval and changing infers that mobile characteristic coefficient territory also will follow the Reynolds number constant interval and beat.At first clear and definite by experiment

Really follow the reynolds number Re constant interval and beat, secondly not exclusively observe and classically differentiate: laminar flow Re≤2320; Turbulent flow 3000＜Re≤10 ⁵Turbulent fully, region of quadratic resistance law Re＞10 ⁵Common Reynolds number constant interval division principle.

Fig. 3 is the synoptic diagram that concerns of corresponding each the flow section in mobile characteristic coefficient territory.Relation between fluid flow and the pressure differential has been carried out diagram, and H is an ordinate with Δ P-Δ, is horizontal ordinate with Q.

1) laminar region: pressure reduction is big more, the curved line relation that rate of flow of fluid is more little; Fig. 3 left side section.

2) turbulent region: pressure reduction is big more, the curved line relation that rate of flow of fluid is big more; Fig. 3 centre portion.

3) turbulent fully, region of quadratic resistance law: pressure reduction is big more, the near linear relation that rate of flow of fluid is big more; Fig. 3 right side section.

As seen from the figure, in fact be divided into three different flow sections, can adopt mathematical method to oversimplify quantitative differentiated treatment, no longer need carry out fluidised form and qualitatively judge by reynolds number Re.Only there is the division on the mathematical meaning this moment.

Separating under not unique situation, in one group of matched curve, choose which root curve and be " best "? best standard is a principle of least square method, makes the quadratic sum δ of error reach minimum exactly.And the index R of the goodness of fit ²Value is maximum, by two-parameter common judgement.

During concrete enforcement: it is 1% that sampling step length is recommended Δ P-Δ H, and self learning system is constituted by high, medium and low, standby four multi-line section matched curves at least.Extreme case can continue to open up.

Sampling natural number Δ P-Δ H occurs in curve fitting process with sampling dependent variable Q that " the quadratic sum δ of error becomes greatly, and the index R of the goodness of fit ²Value diminishes ", and continue more than three steps, think for just may be from three different flow sections one to leap to another one flow section, adopt this moment mathematical way to operate matched curve redirect processing.

Initially from the stage casing, gather Δ P-Δ H and Q carries out curve fitting by 1% step-length, self study obtains first group of flow sector data such as Aa, Ba, Ca, Da (index is learned the subregion on the meaning); Cross this flow section, after the redirect three steps values of front are moved into new section (entering high or low section) and learn second group of flow sector data such as Ab, Bb, Cb, Db again according to direction.When another satisfies matched curve redirect treatment conditions, then call dead section such as Ac, Bc, Cc, Dc.Assurance move up and down study all have in advance three sections (from middle and high, to dead section, or in, low, arrive dead section again.)

Because each flow section sampling natural number value number is indefinite, can only calculates the Mean Square Error amount and be

By data analysis δValue should promptly ought not greater than 0.02 be reasonable value δThink that less than 0.02 o'clock the match computing is normal, otherwise be judged as unusual.It is based on the rigid index of fitting precision.

R ²Index as the check regression equation and the sample value goodness of fit: R ²(0≤R ²≤ 1) big more, represent the good more of regression equation and sample match; Otherwise regression equation and sample value match are relatively poor.The index of the goodness of fit is used to illustrate the tightness degree between the multivariate of nonstraight line correlation.

Or Wherein, n is the number of sample observations, and k is the number (k=m=3) of explanatory variable.

The index R of the goodness of fit ²Value reduces above 1%, i.e. 0.99R ² _Before〉=R ² _AfterThen counting beginning continues three times and then operates the matched curve redirect.Mode with form exemplifies four groups of representational sample calculation results:

Experiment 1

Fig. 4 is the match relationship degree curve of fluid flow value and mirror image flow value in the experiment 1.Blue line is the measured curve of fluid flow value Q, and red line is represented the mirror curve of mirror image flow value q '.Fluid is in laminar condition among the figure, experiment Re≤1172, and flow and front and back pressure differential deltap P-Δ H are all less.The contrast back finds that two curves are not very lubricated, and maximum error has-0.99596%.Analyzing its reason is because the flow absolute value is too small, has observational error.Ordinate: flow range, horizontal ordinate: the number of sample observations.

Experiment 2

Fig. 5 is the match relationship degree curve of fluid flow value and mirror image flow value in the experiment 2.The fluid leading portion is in turbulent region 19938＜Re≤73359 among the figure, and back segment is in fully turbulent zone Re＞73359, and flow and front and back pressure differential deltap P-Δ H change greatly.The contrast back finds that both matches are more satisfactory, and maximum error has 0.10445%.

Experiment 3

Fig. 6 is the match relationship degree curve of fluid flow value and mirror image flow value in the experiment 3.The fluid leading portion is in turbulent region 19938＜Re≤73359 among the figure, and back segment is in fully turbulent zone Re＞73359, and flow and front and back pressure differential deltap P-Δ H change greatly.The contrast back finds that both matches are satisfactory, and maximum error has-0.00000834393%, can ignore.

Experiment 4

Fig. 7 is the match relationship degree curve of fluid flow value and mirror image flow value in the experiment 4.Fluid is in turbulent region 6687＜Re≤65352 among the figure, and flow and front and back pressure differential deltap P-Δ H change greatly.The contrast back finds that two curves are not very lubricated, and match is more satisfactory, and maximum error has-0.58668%.

Other situation is described and data analysis:

According to different fluidised forms and pipeline condition, the front and back codeposition has tired out 7 groups of experimental datas, is 4 groups of experimental datas that therefrom extract above.

Foundation

Mirror image flow value algorithm optimization expression formula is handled and is analyzed all experimental datas, through comparison more than a year, from " make the quadratic sum δ of error reach minimum, and the index R of the goodness of fit ²Value is maximum " see credible result in the two-parameter common judgement self study match accuracy.

Wherein with mirror image flow value mirror image algorithm optimization expression formula carried out the comparison algorithm have: first kind of depression of order algorithm

Exponent number descends, and flexibility reduces, and needs the preparation line segment quantity of match to rise the Mean Square Error amount δBecome big significantly, goodness of fit index R ²Reduce about 1～5%.Second kind of shortcut calculation

With

Checking δEffect slightly is better than first kind of depression of order algorithm, just R ²Reduce not obvious.

The third rises order algorithm

The The Fitting Calculation workload significantly strengthens, and exponent number rises, and flexibility improves, and applying sampled value ability is strengthened, the Mean Square Error amount δBecome littler, goodness of fit index R ²Quite.

Conclusion: to classical formulas

After counting the reason tectonic analysis, the mirror image flow value algorithm optimization expression formula that obtains:

Be an appropriate expression formula that embodies Δ P-Δ H, Q, θ triadic relation, and unique variable Δ P-Δ H.After its simplification, can not satisfy the demand of fitting precision.After it was risen rank, sampling study section fitting precision improved not obvious, but the decline of the precision of prediction of the section of stretching out.What take in addition is that mathematical way is described, computing method, is specially adapted to Computing and handles.

As can be seen, manometric detection signal constituted jointly before and after a kind of virtual flowmeter based on the mirror image flow rate testing methods was summed up as Real-time and Dynamic, on-line operation model in fact and inserts the equipment flowmeter installed, pipeline section.It both can be configured to the small-sized independently embedded controller of a cover separately and be installed in scene or pulpit dish (cabinet) dress, also this operational model can be moved on to computing in the relevant automation control system in the mode of software product (as functional block).Even be set directly at complete formation electromechanical integrated product in the equipment flowmeter secondary table.

The above only preferably is not limited to the present invention for of the present invention, and obviously, those skilled in the art can carry out various changes and modification and not break away from the spirit and scope of the present invention the present invention.Like this, if of the present invention these are revised and modification belongs within the scope of claim of the present invention and equivalent technologies thereof, then the present invention also is intended to comprise these changes and modification interior.

Claims (6)

1. the mirror image flow rate testing methods is characterized in that, comprises the steps:

1) measures the pressure and the pipeline inner fluid flow of pipeline rear and front end; According to following formula, self study obtains the mobile characteristic coefficient territory θ of pipeline:

In the following formula, Q is a pipeline inner fluid flow value; I is the value number; M is the number of explanatory variable;

Be mobile characteristic coefficient territory, wherein comprise specify pipe characteristic (1, d, ε) with characteristic of fluid (ρ, η); Δ P-Δ H is for specifying the pressure differential of pipeline rear and front end;

2), obtain pipeline inner fluid mirror image flow value q ' by following formula according to the pressure of mobile characteristic coefficient territory with the pipeline rear and front end that records:

。

2. mirror image flow rate testing methods as claimed in claim 1 is characterized in that: also comprise the steps:

3) when the pipeline inner fluid flow value generation deviation that records, with the pipeline inner fluid flow value Q that records and or pipeline inner fluid mirror image flow value q ' in big value export as flow value;

Repeated execution of steps 1,2,3), dynamically obtains pipeline inner fluid flow value and mirror image flow value, and constitute redundancy relationship.

3. mirror image flow rate testing methods as claimed in claim 2 is characterized in that: in the step 3), judge by following steps whether the pipeline inner fluid flow value that records deviation takes place:

When the mirror image flow value q ' of step 3) gained more than or equal to 1.06 times of pipeline inner fluid flow value Q, and Δ P-Δ H variation range is in 10%, and pipeline section upstream section gross head pressure P _BeforeAnd pipeline section downstream section gross head pressure P _AfterVariation range also in 10%, is then judged pipeline inner fluid flow value generation deviation.

4. virtual flowmeter is characterized in that: comprising:

At least two pressure transducers are used for the pressure of measuring channel rear and front end;

Self-learning module receives the pressure and the pipeline inner fluid flow value data of specifying the pipeline rear and front end, and according to following formula, self study obtains the mobile characteristic coefficient territory θ of pipeline:

In the following formula, Q is a pipeline inner fluid flow value; I is the value number; M is the number of explanatory variable;

Be mobile characteristic coefficient territory, wherein comprise specify pipe characteristic (1, d, ε) with characteristic of fluid (ρ, η); Δ P-Δ H is for specifying the pressure differential of pipeline rear and front end.

Virtual flow computing module is used for being obtained the mirror image flow value q ' of pipeline inner fluid by following formula according to the pressure of mobile characteristic coefficient territory with the pipeline rear and front end that records:

In the following formula, i is the value number; M is the number of explanatory variable;

Be mobile characteristic coefficient territory, wherein comprise specify pipe characteristic (1, d, ε) with characteristic of fluid (ρ, η); Δ P-Δ H is for specifying the pressure differential of pipeline rear and front end.

5. virtual flowmeter as claimed in claim 4 is characterized in that: also comprise:

The measured value read module is used for obtaining synchronously the fluid flow value in the pipeline, the force value of rear and front end;

Memory module, the mobile characteristic coefficient territory that is used to store this appointment pipeline.

6. virtual flowmeter as claimed in claim 5 is characterized in that: also comprise:

Output stream value handover module, in order to judge when specifying the mobile feature of pipeline section not occur suddenling change, whether monitored pipeline inner fluid flow value has deviation, if any, then stop self study, the big value during the pipeline inner fluid flow value Q that records and pipeline inner fluid mirror image flow value q ' are compared is exported as the flow results value.

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