CN209372153U - Potential formula laminar flow measuring device - Google Patents
Potential formula laminar flow measuring device Download PDFInfo
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- CN209372153U CN209372153U CN201920141387.0U CN201920141387U CN209372153U CN 209372153 U CN209372153 U CN 209372153U CN 201920141387 U CN201920141387 U CN 201920141387U CN 209372153 U CN209372153 U CN 209372153U
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Abstract
The utility model discloses a kind of potential formula laminar flow measuring devices.Measurement pipe routes the identical parallel branch composition of two calibers, two different laminar flow elements of every branch road series connection length, the laminar flow element of two branch roads identical installation site crossed-symmetrical two-by-two is constituted in addition to length laminar flow element relative position difference, other identical two branches.Open pressure port in pressure chamber middle position on every road Tiao Zhi between two laminar flow elements, measure the differential pressure between two pressure chambers, referred to as potential, this differential pressure value size is proportional to the volume flow for flowing through measurement pipeline, and tested volume flow is calculated by differential pressure using the respectful leaf law of Ha Gen-uncle.Capillary pipe length in each laminar flow element is required to be more than developing flow length and flow in laminar condition when specific implementation.The measuring device avoids the non-linear effects of traditional laminar flow flowmeter laminar flow element inlet and outlet crushing and entrance flowing crushing, accurate measurement easy to accomplish and broader range.
Description
Technical field
The utility model relates to flow measurement technology field, specially a kind of potential formula laminar flow measuring device.
Background technique
Laminar flow flowmeter has many advantages, such as no movable member, is able to carry out instantaneous flow measurement, surveys in minute gas flow
Amount and instant gas field of flow measurement have relatively broad application.
Laminar flow flowmeter is the linear relationship based on the flow and crushing for flowing through laminar flow element, i.e. the respectful Ye Dinglv of Ha Gen-uncle
Work.But the linear relationship of flow and crushing is only just set up in fully developed laminar flow flowing.Due to practical laminar flow
Entrance fluid resistance loss is nonlinear in meter laminar flow element inlet and outlet flowing kinetic energy rejection and capillary, non-in order to reduce
For linear crushing accounting to improve measurement accuracy, capillary draw ratio design value requires bigger, capillary when high-acruracy survey
Draw ratio requires more than 500.Consider from flowmeter length and crushing, common laminar flow flowmeter capillary draw ratio will not take so
Greatly, the correction result that non-linear effects are resolved using the modified method of discharge coefficient, but to have been reached is often relatively more tired
Hardly possible pays other costs.
It can be largely by inlet and outlet kinetic energy rejection and entrance stream using differential type laminar flow measuring device
The non-linear effects of dynamic loss balance out.The thinking of this device is the laminar flow element different using two length of series connection, takes this
The difference of two laminar flow element both ends differential pressures, i.e. differential pressure difference.For incompressible fluid, differential pressure difference value is strictly proportional to volume
Flow.But this device needs two differential pressure pick-ups, thus introduces between differential pressure pick-up caused by performance difference
Measurement error also increases cost.In addition, flowing for compressible gas, differential type laminar flow measuring device can not
Non-linear component is completely counterbalanced by, it is necessary to be further improved.
Utility model content
In order to overcome entrance flow losses in laminar flow flowmeter inlet and outlet Capillary Flow loss and capillary non-linear
It influences, is improved on the basis of differential type laminar flow measuring device, propose the utility model, i.e. potential formula laminar flow
Flow measurement device.It is specific as follows:
Measurement pipe routes 2 two parallel branches of the identical branch one of caliber and branch and forms, containing there are four laminar flows on pipeline
Element, laminar flow element internal capillary pipe diameter sum number amount is all identical, and laminar flow element length is identical two-by-two, that is, one He of laminar flow element
Laminar flow element four is identical, length L1, laminar flow element two and laminar flow element three are identical, length L2, L2>L1.One He of laminar flow element
Laminar flow element three is installed in series on branch one, and laminar flow element two and laminar flow element four are installed in series on branch two.
Flow conditioner one and flow conditioner two, two flow conditioner specifications are respectively provided on branch one and branch two
It is identical with relative mounting location.In addition, remaining connecting line is all symmetrical relative to measurement pipeline inlet and outlet.In this way,
It is entire to measure pipeline other all identical, two branch other than the crossed-symmetrical of length laminar flow element relative position from the inlet to the outlet
Road flow resistance (pressure loss) characteristic is identical.
It is pressure chamber between each laminar flow element of road two, the pressure chamber length of two branch roads is identical.It takes
Pressure chamber middle position is provided with pressure port, between laminar flow element one and laminar flow element three, laminar flow element two and laminar flow element four it
Between the pressure pipe drawn of pressure port be coupled with the positive pressure and negative pressure terminal of differential pressure pick-up, read between two pressure chambers
Differential pressure, referred to as potential.This differential pressure value size is proportional to the volume flow for flowing through measurement pipeline, respectful using Ha Gen-uncle
Measured flux is calculated by differential pressure in leaf law.The total volumetric flow rate for flowing through two branches is
Wherein, the number of capillary in the single laminar flow element of n--；
D-- capillary equivalent diameter；
The dynamic viscosity of μ -- fluid；
Δ P-- potential；
The difference of middle capillary pipe length, Δ L=L in two kinds of length laminar flow elements of Δ L--2-L1。
C-- discharge coefficient.
When using this measuring device, several technical requirements or problem are noted also:
1) in order to which the developing flow pressure loss to be completely counterbalanced by, capillary pipe length is required more than in each laminar flow element
Developing flow length；
2) flow in capillary tube need to be in laminar condition in laminar flow element.
3) for incompressible fluid flow measurement, capillary imports and exports entrance flowing damage in kinetic energy rejection and capillary
Lose two kinds of nonlinear loss items can automotive resistance fall, therefore, flow coefficient C is constant；For compressible fluid, such as into
When row gas flow measurement, density and volume flow variation on the way, the hair of laminar flow element caused by the compressibility of gas are considered
Fluid resistance loss cannot be completely counterbalanced by tubule outlet crushing and pressure chamber, and there are still flow coefficient Cs for non-linear effects
It is not constant.In the case of two kinds, the numerical value of flow coefficient C requires to determine by calibration experiments.
The utility model has the beneficial effect that
1) in the measuring device, by the identical parallel branch of two flow resistance characteristics of construction, two branch middle and upper reaches are measured
Differential pressure between laminar flow element outlet chamber, i.e. potential, to obtain flow.For incompressible fluid, laminar flow element
Middle capillary inlet, outlet crushing, entrance flow losses, the indoor fluid resistance loss of pressure chamber etc. are non-linear in capillary
Ingredient is fallen by automotive resistance, is not embodied in potential, therefore the differential pressure is strictly directly proportional to volume flow.Even for can
Compressed gas flow, laminar flow element capillary inlet kinetic energy rejection and the loss of entrance viscous friction drag can also be canceled out,
Fluid resistance loss can be largely canceled out in capillary outlet crushing and pressure chamber, quiet for pressure loss fluid relative
The lesser situation of pressure ratio, non-linear component has been greatly reduced in differential pressure, so that subsequent correction is more easier.
2) this measuring device is used, flow is proportional to potential value, and flow measurement mathematical model is extremely simple, is easy
Realize high accuracy measurement and bigger range ability.
3) this flowmeter, the laminar flow element of each branch middle and upper reaches, can equivalent to increase a flow conditioner
Overcome the influence of various fluidised forms, there is preferably flowing adaptability.
4) this flowmeter, if there is dust etc. is deposited on laminar flow element front half section, as long as pollution condition in two elements
It is identical, measurement result will not be had an impact, therefore flowmeter resists dirty ability strong, long-time stability are good.
Detailed description of the invention
Fig. 1 is the potential formula laminar flow measurement pipeline schematic diagram of the utility model；
Fig. 2 is the potential formula laminar flow measurement pipeline key dimension schematic diagram of the utility model；
Fig. 3 measures pressure loss schematic diagram in pipeline；
In figure: 100- branch one；200- branch two；1- flow conditioner one；2- flow conditioner two；3- laminar flow element
One；4- laminar flow element two；5- laminar flow element three；6- laminar flow element four；7- differential pressure pick-up.
Specific embodiment
The utility model is described further below by attached drawing.
As shown in Figure 1, the measurement pipe routing caliber of the utility model potential formula laminar flow measuring device is identical
2 200 two parallel branch compositions of branch 1 and branch, two length difference laminar flow elements of every branch road series connection, laminar flow
Element 1 and laminar flow element 35 are installed in series on branch 1, and laminar flow element 24 and laminar flow element 46 are installed in series
On branch 2 200.Laminar flow element internal capillary pipe diameter sum number amount is all identical, and the laminar flow element length two of two branch roads
Two is identical, that is, the shorter laminar flow element 1 of length and laminar flow element 46 are identical, the longer laminar flow element 24 of length and laminar flow
Element 35 is identical.It is pressure chamber between two laminar flow elements in each branch road, the pressure chamber length of two branches is identical.Branch
Be respectively provided with flow conditioner 1 and flow conditioner 22 on road 1 and branch 2 200, two flow conditioner specifications and
Relative mounting location is identical.In addition, remaining connecting line is all symmetrical relative to measurement pipeline inlet and outlet.In this way, two
Bypass flow resistance (pressure loss) characteristic is identical.
Pressure chamber middle position on every road Tiao Zhi between two laminar flow elements is provided with pressure port, laminar flow element 1
The pressure pipe that pressure port between laminar flow element 35, between laminar flow element 24 and laminar flow element 46 is drawn is coupled with difference
The positive pressure and negative pressure terminal of pressure sensor 7, read the differential pressure between two pressure chambers, i.e. potential Δ P.
As shown in Fig. 2, 46 equal length of laminar flow element 1 and laminar flow element, is L1；Laminar flow element 24 and laminar flow element
35 equal lengths are L2；L2>L1.The difference of the length of laminar flow element 1 and laminar flow element 24, Δ L=L2-L1.Two branch roads
Pressure chamber length is identical, is e, and e is generally 1-2 times of the internal diameter of pressure chamber.Flow conditioner is to laminar flow in two branches
The distance of element inlet is e', and e' is 1 times or so of internal diameter of the pipeline.
Fig. 3 is the pressure loss schematic diagram for measuring pipeline middle layer fluid element 1 and laminar flow element 24.As shown in the figure, it is assumed that
The pressure in flow conditioner to chamber middle position between laminar flow element is P0, the pressure of pressure chamber pressure measurement points on branch one
Power is P1, the pressure of pressure chamber pressure measurement points is P on branch two2, two branch laminar flow elements 1 and 24 liang of laminar flow element
The pressure loss at end is respectively as follows: Δ P1=P0-P1, Δ P2=P0-P2。
ΔP15 can be divided into, i.e.,
ΔP1=Δ P11+ΔP12+ΔP13+ΔP14+ΔP15 (1)
Wherein, Δ P11-- chamber intermediate point is to one 3 capillary of laminar flow element between flow conditioner 1 and laminar flow element 1
Tube inlet along journey friction loss；
ΔP12-- capillary inlet flows kinetic energy rejection；
ΔP13-- along journey friction loss in capillary；
ΔP14-- capillary outlet flows kinetic energy rejection；
ΔP15-- pressure chamber inner capillary tube export to pressure port along journey friction loss.
It is two parts, L by 24 points of laminar flow element2=L21+ Δ L, wherein L21With L1It is identical.Then Δ P26 can be divided into, i.e.,
ΔP2=Δ P21+ΔP22+ΔP23+ΔP24+ΔP25+ΔP26 (2)
Wherein, Δ P21-- chamber intermediate point is to one capillary of laminar flow element between flow conditioner 22 and laminar flow element 24
Entrance along journey friction loss；
ΔP22-- capillary inlet flows kinetic energy rejection；
ΔP23-- capillary front half section L21Along journey friction loss in length；
ΔP24-- capillary outlet flows kinetic energy rejection；
ΔP25-- pressure chamber inner capillary tube export to pressure port along journey friction loss；
ΔP26-- along journey friction loss in capillary second half section Δ L length.
For incompressible fluid, Δ P11=Δ P21, Δ P12=Δ P22, Δ P13=Δ P23, Δ P14=Δ P24, Δ P15
=Δ P25, i.e., pressure loss dotted line and fine line part respectively correspond equal in figure, can be completely counterbalanced by, then potential value
Δ P=P1-P2=(P1-P0)-(P2-P0)=Δ P2-ΔP1=Δ P26 (3)
It has been fully developed section flowing, therefore edge caused by fluid viscosity in the capillary second half section in laminar flow element 24
Journey fricting resistance loss Δ P26Comply fully with the respectful Ye Dinglv of Ha Gen-uncle, i.e. Δ P=Δ P26It is linear with volume flow Q,
It is by the formula that differential pressure calculates volume flow
Wherein, the number of capillary in the single laminar flow element of n--；
D-- capillary equivalent diameter；
The dynamic viscosity of μ -- fluid；
Δ P-- potential；
The difference of middle capillary pipe length, Δ L=L in two kinds of length laminar flow elements of Δ L--2-L1。
C-- discharge coefficient.
It should be noted that L1It should be greater than flow in capillary tube length at entry, otherwise non-linear component cannot be complete in Δ P
Full removal.
In addition, capillary imports and exports entrance stream in kinetic energy rejection and capillary for incompressible fluid flow measurement
Dynamic two kinds of nonlinear loss items of loss can automotive resistance fall, therefore, flow coefficient C is constant；For compressible fluid, example
When such as carrying out gas flow measurement, density and volume flow variation on the way, laminar flow element caused by the compressibility of gas are considered
Capillary outlet crushing and pressure chamber in fluid resistance loss cannot be completely counterbalanced by, there are still flows for non-linear effects
Coefficient C is not constant.In the case of two kinds, the numerical value of flow coefficient C requires to determine by calibration experiments.Certainly, for pressure
The lesser situation of fluid relative static pressure ratio is lost, non-linear component has been greatly reduced in differential pressure Δ P, so that subsequent correction is very
It is easy.
The foregoing is merely the basic ideas of the utility model and methods, are not intended to limit the utility model, all at this
Any modifications, equivalent replacements, and improvements etc. done within the thinking and principle of utility model, should be included in the utility model
Protection scope within.
Claims (3)
1. a kind of potential formula laminar flow measuring device, including measurement pipeline, it is characterised in that: the measurement pipe routing pipe
Diameter is identical, two parallel branches of the symmetrical branch one (100) of inlet and outlet connecting tube and branch two (200) form, branch one (100)
On set gradually flow conditioner one (1), laminar flow element one (3) and laminar flow element three (5)；It is set gradually on branch two (200)
Flow conditioner two (2), laminar flow element two (4) and laminar flow element four (6), the pressure between two laminar flow elements in every branch road
Chamber middle position is provided with pressure port, between laminar flow element one (3) and laminar flow element three (5), laminar flow element two (4) and laminar flow member
The pressure pipe that pressure port between part four (6) is drawn is coupled with the positive pressure and negative pressure terminal of differential pressure pick-up (7).
2. a kind of potential formula laminar flow measuring device according to claim 1, it is characterised in that: the laminar flow member
Part one (3), laminar flow element two (4), laminar flow element three (5), laminar flow element four (6) internal capillary pipe diameter are identical with radical, compared with
Short laminar flow element one (3) is identical with laminar flow element four (6) length, length L1, longer laminar flow element two (4) and laminar flow are first
Part three (5) length is identical, length L2, L2>L1。
3. a kind of potential formula laminar flow measuring device according to claim 1, it is characterised in that: two branch roads
Flow conditioner one (1) it is identical with relative mounting location with flow conditioner two (2) specification.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201920141387.0U CN209372153U (en) | 2019-01-25 | 2019-01-25 | Potential formula laminar flow measuring device |
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| CN201920141387.0U CN209372153U (en) | 2019-01-25 | 2019-01-25 | Potential formula laminar flow measuring device |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109738030A (en) * | 2019-01-25 | 2019-05-10 | 中国计量大学 | Potential formula laminar flow measurement method and device |
| CN111272236A (en) * | 2020-02-26 | 2020-06-12 | 西北工业大学 | Gas flow calculation method of gas laminar flow meter and gas laminar flow meter |
-
2019
- 2019-01-25 CN CN201920141387.0U patent/CN209372153U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109738030A (en) * | 2019-01-25 | 2019-05-10 | 中国计量大学 | Potential formula laminar flow measurement method and device |
| CN109738030B (en) * | 2019-01-25 | 2023-10-03 | 中国计量大学 | Pressure potential difference type laminar flow measuring method and device |
| CN111272236A (en) * | 2020-02-26 | 2020-06-12 | 西北工业大学 | Gas flow calculation method of gas laminar flow meter and gas laminar flow meter |
| CN111272236B (en) * | 2020-02-26 | 2021-07-30 | 西北工业大学 | Gas flow calculation method of gas laminar flow meter and gas laminar flow meter |
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