CN1240930A - Vortex flow sensor - Google Patents
Vortex flow sensor Download PDFInfo
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- CN1240930A CN1240930A CN 99108600 CN99108600A CN1240930A CN 1240930 A CN1240930 A CN 1240930A CN 99108600 CN99108600 CN 99108600 CN 99108600 A CN99108600 A CN 99108600A CN 1240930 A CN1240930 A CN 1240930A
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Abstract
This sensor for measuring the flow velocity and/or the flow rate of a fluid provides an optical sensor system which is also suitable for use at temperatures higher than 400 DEG C., does not come into contact with the fluid, and requires less space than conventional optical sensor systems. The sensor comprises a tube (1) through which the fluid flows in a first direction and which has a wall (11) in which a first window (2) and a second window (3) of optical, schlieren-free, high-temperature glass are set fluid-tight and pressure-tight at points lying opposite each other along a first tube diameter. A bluff body (4) is disposed along a second tube diameter and fixed in the tube for generating Karman vortices, whose frequency f is proportional to the flow velocity u. The second diameter is up-stream of, and perpendicular to, the first. A laser differential interferometer (6, 6') has a transmitting unit (61, 61') and a receiving unit (62, 62').
Description
The present invention relates to a kind of eddy current sensor, this eddy current sensor is used for measuring the rate of flow of fluid that flows at measuring tube and/or by the flow of volumometer.
Common eddy current sensor has bluff, and this bluff is along the diameter setting of measuring tube and be fixed on the tube wall.
As everyone knows, when this eddy current sensor is worked, form Karman vortex street in the downstream of bluff.Its pressure surge converts electric signal to by sensitive element, and this electric signal frequency is directly proportional with flow velocity, can calculate the flow by volumometer thus.
On the one hand, the eddy current sensitive element that uses at present is to stretch into fluid and directly bear the device of pressure surge; These devices for example, are pressure transducer, especially capacitive transducer, and these sensors are installed in the bluff or pack into or insert the wall that passes measuring tube in the downstream of this bluff.
On the other hand, measure pressure surge with a Vltrasonic device, the transmitter of this Vltrasonic device and receiver are installed in the measuring tube outside relative to one another along diametric(al).Transmitter passes measures tube wall, fluid and relative wall transmission ultrasonic signal, and the device record is modulated and be received to this signal by this pressure surge.
The inherent defect of these two kinds of sensitive elements is that the eddy current sensor of these sensitive elements of assembling can not be used for all fluids.Ultrasonic sensor only can be used for being about 250 ℃ fluid temperature (F.T.), and capacitance pressure transducer, only can be used for being about 400 ℃ fluid temperature (F.T.).
In addition, also described such eddy current sensor, wherein light or laser beam are passed fluid and are used for determining the eddy current frequency through the beam intensity modulation that the effect of eddy current body produces; For example, referring to U.S. patent 4,519,259 or GB-A 2,084,720.This smooth eddy current sensor also can bear the temperature greater than 400 ℃.
The purpose of this invention is to provide a light sensor system, this system can use in greater than 400 ℃ temperature, and it does not contact with fluid, and used space is less than common light sensor system.
For achieving this end, the first string of the present invention provides one and is used to measure rate of flow of fluid and/or by the eddy current sensor of the flow of volumometer, described eddy current sensor comprises:
A measuring tube, fluid flows through measuring tube with first direction, measuring tube has a wall, some place's fluid-tight respect to one another of first diameter of this described measuring tube in wall upper edge and pressure seal first and second windows of no striped high temperature optical glass are set;
One along the second diameter setting of described measuring tube and be fixed on the bluff that is used for producing at this fluid the Karman vortex fluid in this measuring tube, its frequency is directly proportional with flow velocity, and described second diameter is positioned at the upstream of described first diameter and substantially perpendicular to this first diameter;
A laser differential interferometer, it has a transmitter unit that is in the described measuring tube outside of this first window front and is fixed to this first window and/or this measuring tube, and described transmitter unit comprises the following optics that is arranged in order along the direction of trend first window:
A laser instrument,
A lens combination,
One first polarizing filter,
One first Wollaston (Wollaston) prism and
One first lens;
The outside of a described measuring tube that is in this second window front also is fixed to the receiving element of this second window and/or this measuring tube, and described receiving element comprises the following optics that is arranged in order along the direction of leaving from this second window:
One second lens,
One second wollaston prism,
One second polarizing filter and
A PIN diode.
To achieve these goals, second scheme of the present invention provides one and is used to measure rate of flow of fluid and/or by the eddy current sensor of the flow of volumometer, described eddy current sensor comprises:
A measuring tube, fluid flows through measuring tube with first direction, measuring tube has a wall, some place's fluid-tight respect to one another of first diameter of this described measuring tube in wall upper edge and pressure seal first and second windows of no striped high temperature optical glass are set;
One along the second diameter setting of described measuring tube and be fixed on the bluff that is used for producing at this fluid the Karman vortex fluid in this measuring tube, its frequency is directly proportional with flow velocity, and described second diameter is positioned at the upstream of described first diameter and substantially perpendicular to this first diameter;
A laser differential interferometer, it has a transmitter unit that is in the described measuring tube outside of this first window front and is fixed to this first window and/or this measuring tube, and described transmitter unit comprises the following optics that is arranged in order along the direction of trend first window:
The laser instrument of a polarized light-emitting,
A lens combination,
One first wollaston prism and
One first lens;
The outside of a described measuring tube that is in this second window front also is fixed to the receiving element of this second window and/or this measuring tube, and described receiving element comprises the following optics that is arranged in order along the direction of leaving from this second window:
One second lens,
One second wollaston prism,
Polarizing filter and
A PIN diode.
In the preferred embodiment of the present invention first or alternative plan, first and second lens are achromat.
An advantage of the invention is both to make fluid temperature (F.T.) up to for example 600 ℃, this fluid still can be measured according to vortex principle.
Another advantage of the present invention is because optics can use the manufacturing of microsystem technology, and therefore, the occupied space of optical sensor system is less than common sensing system.
When in conjunction with the accompanying drawings following example being illustrated, it is clearer that the present invention will become, wherein:
Fig. 1 represents to have the longitudinal profile of the measuring tube of eddy current sensor;
Fig. 2 represents each parts and the relevant beam path of the laser differential interferometer of the present invention's first scheme; With
Fig. 3 represents each parts and the relevant beam path of the laser differential interferometer of alternative plan of the present invention.
Referring to Fig. 1, Fig. 1 illustrates the longitudinal profile of the signal of a measuring tube 1, and a fluid flows through measuring tube 1 along direction shown in the arrow, and the flow of pressing volumometer and/or the flow velocity of this fluid are measured.This fluid can be liquid, gas or steam.
Bluff 4 is installed on the measuring tube 1 along second diameter.This second diameter is positioned at the upstream of first diameter and substantially vertical with this first diameter.Bluff 4 is used for producing Karman vortex fluid 5 at fluid, and what eddy current body 5 streamwises were seen alternately distributes from bluff 4 from left hand shunting limit 41 and right hand shunting limit 42.As everyone knows, eddy current shunting frequency is directly proportional with the xsect A of flow velocity u and measuring tube 1 cavity; Can calculate flow according to this tittle by volumometer:
Q＝uA；u＝kf；Q＝kAf，
Wherein, k is measured in the calibration steps of an ededy current gauge constant.
Laser differential interferometer 6 (see figure 2)s or 6 ' (see figure 3) have the transmitter unit 61 or 61 that is in measuring tube 1 outside ' and receiving element 62 or 62 ', transmitter unit is positioned at the front of window 2, receiving element is positioned at the front of window 3.
Transmitter unit and receiving element are respectively fixed to window 2 and 3, and/or are fixed to measuring tube 1, and relatively moving between this measuring tube of feasible generation spur signal and transmitter unit and the receiving element avoided.
Fig. 2 illustrates each parts of laser differential interferometer 6 of the present invention's first scheme and the path of associated beam.In the direction of window 2, the following optics of transmitter unit 61 is provided with continuously: laser instrument 21, the first lens combination 22, the first polarizing filters, 23, the first wollaston prisms 24 and first lens 25, the preferably achromat.
After passing this fluid, two light beams 71,72 arrive receiving element 62.Along leaving on the direction of window 3, the optics of following receiving element 62 is provided with continuously: second lens 26, achromat preferably, second wollaston prism, 27, the second polarizing filters 28 and PIN diode 29.
Pass after this fluid, lens 26 and wollaston prism 27 make two light beams 71,72 synthesize a single light beam 7 ", as is known, produce phase differential thereby form heterodyne by polarizing filter 28.These phase differential are converted to electric signal by PIN diode 29, and available suitable frequency measurement electronic equipment is measured the frequency of electric signal easily.Described frequency measurement electronic equipment is existing and commercially available, and this paper does not explain them.
Fig. 3 illustrate the laser differential interferometer 6 of alternative plan of the present invention ' each parts and the path of associated beam.In the direction of window 2, transmitter unit 61 ' following optics be provided with continuously: the laser instrument 31 of polarized light-emitting, lens combination 32, the first wollaston prisms 34 and first lens 35, the preferably achromat.
Compare with Fig. 2, because therefore laser instrument 31 polarized light-emitting, does not need to be provided with and polarizing filter 23 corresponding polarizing filters.The light that lens combination 32 is launched laser instrument 31 with the form of light beam 17 directly focuses on wollaston prism 34, wollaston prism 34 is divided into first and second orthogonal polarized light beams 171,172 that angle is α with light beam 17, is e at the spacing distance that leaves lens 25 rear polarizer light beams 171 and 172.
After passing this fluid, two light beams, 171,172 arrival receiving elements 62 '.Along leaving on the direction of window 3, receiving element 62 ' following optics be provided with continuously: second lens 36, the second wollaston prisms 37, polarizing filter 38 and the PIN diode 39.
Pass after this fluid, lens 36 and wollaston prism 37 make two light beams 171,172 synthesize a single light beam 17 ", and by polarizing filter 38 generation heterodynes.The phase differential that is produced is converted to electric signal by PIN diode 39, and available suitable frequency measurement electronic equipment is measured the frequency of these electric signal easily.
In the present invention, the eddy current body 5 from bluff 4 shuntings is carried out optical assessment along the cyclical variation of caused this fluid density of this laser path.The accessible measuring limit of the present invention is determined by the resolution of laser differential interferometer:
g＝δd/e
Here, δ d is the instantaneous density gradient along two laser 71,72 or 171,172 light paths.
Density d can be calculated according to the Lorentz-Lorenz formula:
d＝(n
2-1)/R(n
2+2)
Here, n is a refractive index, and R is based on the specific refraction coefficient of this fluid of optical wavelength l.
For example, during for air and wavelength value l=632nm, refraction coefficient R=0.0000152m
3/ kg.Because it only is 3% that this refraction coefficient R changes, therefore can suppose that it is constant in wide pressure and temperature scope.
Because have only the variable δ n that produces in above-mentioned density gradient δ d appearance and the refractive index very little, therefore above Lorentz-Lorenz formula can be reduced to:
δd/δn＝6n/R(n
2+2)
2
In addition, δ n=1/D
Here, D is the diameter of measuring tube 1.
For l=632nm, e=2mm during D=53mm, can obtain resolution g=0.00262kg/ (m
3Mm).If measured fluid is a gas, then for the flow velocity greater than 2m/s, this resolution is enough.
Claims (3)
1. one kind is used to measure rate of flow of fluid and/or by the eddy current sensor of the flow of volumometer, described eddy current sensor comprises:
A measuring tube, fluid flows through measuring tube with first direction, measuring tube has a wall, some place's fluid-tight respect to one another of first diameter of this described measuring tube in wall upper edge and pressure seal first and second windows of no striped high temperature optical glass are set;
One along the second diameter setting of described measuring tube and be fixed on the bluff that is used for producing at this fluid the Karman vortex fluid in this measuring tube, its frequency is directly proportional with flow velocity, and described second diameter is positioned at the upstream of described first diameter and substantially perpendicular to this first diameter;
A laser differential interferometer, it has a transmitter unit that is in the described measuring tube outside of this first window front and is fixed to this first window and/or this measuring tube, and described transmitter unit comprises the following optics that is arranged in order along the direction of trend first window:
A laser instrument,
A lens combination,
One first polarizing filter,
One first wollaston prism and
One first lens;
The outside of a described measuring tube that is in this second window front also is fixed to the receiving element of this second window and/or this measuring tube, and described receiving element comprises the following optics that is arranged in order along the direction of leaving from this second window:
One second lens,
One second wollaston prism,
One second polarizing filter and
A PIN diode.
2. one kind is used to measure rate of flow of fluid and/or by the eddy current sensor of the flow of volumometer, described eddy current sensor comprises:
A measuring tube, fluid flows through measuring tube with first direction, measuring tube has a wall, some place's fluid-tight respect to one another of first diameter of this described measuring tube in wall upper edge and pressure seal first and second windows of no striped high temperature optical glass are set;
One along the second diameter setting of described measuring tube and be fixed on the bluff that is used for producing at this fluid the Karman vortex fluid in this measuring tube, its frequency is directly proportional with flow velocity, and described second diameter is positioned at the upstream of described first diameter and substantially perpendicular to this first diameter;
A laser differential interferometer, it has a transmitter unit that is in the described measuring tube outside of this first window front and is fixed to this first window and/or this measuring tube, and described transmitter unit comprises the following optics that is arranged in order along the direction of trend first window:
The laser instrument of a polarized light-emitting,
A lens combination,
One first wollaston prism and
One first lens;
The outside of a described measuring tube that is in this second window front also is fixed to the receiving element of this second window and/or this measuring tube, and described receiving element comprises the following optics that is arranged in order along the direction of leaving from this second window:
One second lens,
One second wollaston prism,
Polarizing filter and
A PIN diode.
3. eddy current sensor as claim 1 or 2, wherein, first and second lens are achromat.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 99108600 CN1240930A (en) | 1998-06-25 | 1999-06-25 | Vortex flow sensor |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP98111663.5 | 1998-06-25 | ||
| US100725 | 1998-09-17 | ||
| CN 99108600 CN1240930A (en) | 1998-06-25 | 1999-06-25 | Vortex flow sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1240930A true CN1240930A (en) | 2000-01-12 |
Family
ID=5273396
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 99108600 Pending CN1240930A (en) | 1998-06-25 | 1999-06-25 | Vortex flow sensor |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1240930A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007016865A1 (en) * | 2005-08-10 | 2007-02-15 | Yu Chen | A flow measuring device of a stream |
| CN100378408C (en) * | 2002-12-03 | 2008-04-02 | Lg电子株式会社 | Flow spreading mechanism |
| CN100465590C (en) * | 2002-12-23 | 2009-03-04 | 博里利斯技术公司 | Catalyst flow meter |
| CN102348958A (en) * | 2009-03-12 | 2012-02-08 | 恩德斯+豪斯流量技术股份有限公司 | Method and vortex flow meter for monitoring and/or measuring a wall flow of a biphasic or multiphase medium flowing in a pipe |
-
1999
- 1999-06-25 CN CN 99108600 patent/CN1240930A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100378408C (en) * | 2002-12-03 | 2008-04-02 | Lg电子株式会社 | Flow spreading mechanism |
| CN100465590C (en) * | 2002-12-23 | 2009-03-04 | 博里利斯技术公司 | Catalyst flow meter |
| WO2007016865A1 (en) * | 2005-08-10 | 2007-02-15 | Yu Chen | A flow measuring device of a stream |
| CN102348958A (en) * | 2009-03-12 | 2012-02-08 | 恩德斯+豪斯流量技术股份有限公司 | Method and vortex flow meter for monitoring and/or measuring a wall flow of a biphasic or multiphase medium flowing in a pipe |
| CN102348958B (en) * | 2009-03-12 | 2014-10-01 | 恩德斯+豪斯流量技术股份有限公司 | Method and vortex flow meter for monitoring and/or measuring a wall flow of a biphasic or multiphase medium flowing in a pipe |
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