EP0842400A1 - Debitmetre a ultrasons - Google Patents

Debitmetre a ultrasons

Info

Publication number
EP0842400A1
EP0842400A1 EP97927071A EP97927071A EP0842400A1 EP 0842400 A1 EP0842400 A1 EP 0842400A1 EP 97927071 A EP97927071 A EP 97927071A EP 97927071 A EP97927071 A EP 97927071A EP 0842400 A1 EP0842400 A1 EP 0842400A1
Authority
EP
European Patent Office
Prior art keywords
flow meter
ultrasonic
wavelength
ultrasonic flow
mesh
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP97927071A
Other languages
German (de)
English (en)
Inventor
Jan Van Bekkum
Vladimir Smychliaev
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Krohne AG
Original Assignee
Krohne AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from DE19648784A external-priority patent/DE19648784C2/de
Application filed by Krohne AG filed Critical Krohne AG
Publication of EP0842400A1 publication Critical patent/EP0842400A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F15/00—Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
    • G01F1/662—Constructional details
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60G—VEHICLE SUSPENSION ARRANGEMENTS
    • B60G2401/00—Indexing codes relating to the type of sensors based on the principle of their operation
    • B60G2401/17—Magnetic/Electromagnetic
    • B60G2401/176—Radio or audio sensitive means, e.g. Ultrasonic

Definitions

  • the invention relates to an ultrasonic flow meter for flowing media, with a measuring tube and with at least two ultrasonic transducers arranged offset in the flow direction, the ultrasonic transducer being installed in contact pockets with the flowing medium in transducer pockets of the measuring tube.
  • ultrasonic flowmeters has become increasingly important in the operational flow measurement of liquids and gases, in summary flowing media.
  • the flow measurement is carried out — as in the case of magnetic-inductive flow meters — “without contact”, ie. H. without disturbing installations in the flow, which always result in turbulence and an increased pressure loss.
  • Ultrasonic flowmeters of the type in question include, on the one hand, a measuring tube which, as a rule, represents the measuring section together with an inlet section and an outlet section, and on the other hand at least two ultrasound transducers which are offset with respect to one another in the flow direction and are also referred to as measuring heads.
  • Ultrasound transducers are to be understood very generally.
  • the ultrasonic transducers include ultrasonic transmitters, ie measuring heads for generating and emitting ultrasonic signals, and secondly ultrasonic receivers, ie measuring heads for receiving ultrasonic signals and for converting the received ultrasonic signals into electrical signals.
  • the ultrasonic transducers also include measuring heads which combine ultrasonic transmitters and ultrasonic receivers, that is to say that they generate and emit ultrasonic signals as well as receive ultrasonic signals
  • ERS ⁇ ZBL ⁇ T (RULE 26) and convert the received ultrasound signals into electrical signals.
  • ultrasonic flow meters on the one hand, in which the ultrasonic transducers do not come into contact with the flowing medium, that is to say are arranged on the measuring tube from the outside, so-called “clamp-on arrangement", and, on the other hand, ultrasonic flow meters which the ultrasonic transducers are in contact with the flowing medium.
  • the invention relates only to those ultrasonic flow meters in which the ultrasonic transducers are in contact with the flowing medium.
  • the ultrasonic transducers are installed in transducer pockets of the measuring tube.
  • Wandlertaschc means a recess or depression, as always realized, outside the flow cross-section of the measuring tube, in which an ultrasonic transducer is installed in such a way that it does not protrude into the flow cross-section of the measuring tube, ie it does not actually influence the flow.
  • the longitudinal axis of the transducer pockets generally runs at an acute angle or at an obtuse angle to the direction of flow of the flowing medium or to Longitudinal axis of the measuring tube (cf. Figure 6.1.1 on page 532 of the literature reference "Sensors, sensors", loc. Cit., Figure 8 on page 18 of VDI / VDE DIRECTIVE 2642 "Ultrasonic flow measurement of liquids in fully flowed pipelines", and 2-2 on page 21 of the reference “Ultrasonic Measurements for Process Control" by Lawrence C. Lynnworth, ACADEMIC PRESS, INC., Edited by Harcourt Brace Jovanovich).
  • the transducer pockets do not leave the flow of the medium flowing in the measuring tube unaffected, rather vortices are generated, with the frequency
  • V velocity of the flowing medium
  • the Strouhal number is about 0.2 and changes little if the Reynolds number is between 2 x 102 and 6 x 105 (see Fig. 2.9 on page 32 of the literature "Boundary-Layer Theory ", loc. cit.).
  • Piezoelectric ultrasound transducers are normally used which have a diameter of 10 to 20 mm, i. H. the size of the recess is between 15 and 40 mm.
  • the frequency of the vortices generated by the transducer pockets is between 2.5 and 133 Hz. If measurements are now to be carried out with an accuracy of 0.1%, then this is the time constant between about 3.8 s and about 200 s. The dynamics of the ultrasonic flow meters in question are therefore poor.
  • the invention is based on the object of thus designing and developing the known ultrasonic flow meters from which the invention is based, that vortices generated by the converter pockets do not have a disadvantageous effect in the manner described.
  • the ultrasonic flow meter according to the invention in which the previously derived and shown object is achieved, is initially and essentially characterized by the fact that the transducer pockets are provided with a mesh on the inlet side. On the input side, this means that the grid is provided where the converter pockets, as seen from the measuring tube, begin.
  • the grids provided according to the invention are only necessary in the respective input area of the converter pockets.
  • the measuring tube as a whole can be provided with a continuous grid on its inside. Then the measuring tube has a uniform roughness overall, whereby the flow profile and thus the measurement result is stabilized.
  • the grids provided according to the invention must of course be ultrasound-permeable. This is ensured if the mesh of the grating has braiding devices F which are smaller than the product of the average depth T of the converter pockets and the wavelength ⁇ of the ultrasound in the flowing medium.
  • the mesh of the grating has braiding devices F which are smaller than the product of the average depth T of the converter pockets and the wavelength ⁇ of the ultrasound in the flowing medium.
  • FIG. 1 shows a longitudinal section through a known ultrasonic flow meter from which the invention is based
  • FIG 3 shows a first exemplary embodiment of an ultrasonic
  • Fig. 5 is a graphical representation for explaining what is by the
  • the ultrasonic flow meters shown in FIGS. 1 to 4 are intended for flowing media, in particular for liquids, but also for gas.
  • the speed of the flowing medium can be measured with the aid of the ultrasound flow meter in question.
  • the flow can be determined from the measured speed and the known flow cross section.
  • the basic design of the ultrasonic flow meters shown in FIGS. 1 to 4 consist of a measuring tube 1 and two ultrasonic transducers 2 arranged offset in the flow direction. Only two ultrasonic transducers 2 are provided in the exemplary embodiments shown; the following explanation of the invention is of course also applicable to
  • REPLACEMENT BUTT (RULE 26) Ultrasonic flow meter in which more than two ultrasonic transducers 2 are provided.
  • the ultrasonic transducers 2 are installed in contact with the flowing medium in transducer pockets 3 of the measuring tube 1.
  • the longitudinal axis of the converter pockets 3 extends at an acute angle or at an obtuse angle to the direction of flow or to the longitudinal axis of the measuring tube 1.
  • FIGS. 3 and 4 Ultrasonic flow meters designed according to the invention are shown in FIGS. 3 and 4.
  • the converter pockets 3, namely only the converter pockets 3, are provided on the input side with a mesh 7 having meshes 6.
  • FIG. 4 shows an embodiment of the ultrasonic flow meter according to the invention, in which the measuring tube 1 is provided on its inside 8 with a continuous grating 7; the measuring tube 1 is consequently provided with a grid 7 as a whole.
  • the grating 7 provided according to the invention must be permeable to ultrasound. This is ensured if the meshes 6 of the grating 7 have braiding devices F which are smaller than the product of the average depth T of the converter pockets and the wavelength ⁇ of the ultrasound in the flowing medium.
  • the meshes 6 of the grid 7 can thus have a circular or an elliptical cross section. Then the diameter of the mesh 6 of the grid 7 is chosen so that it lies between the wavelength ⁇ of the ultrasound in the flowing medium and the doubling of this wavelength.
  • the meshes 6 of the grating 7 can also have a rectangular, in particular a square, or a diamond-shaped cross section. For the dimensioning of the meshes 6 of the grating 7 it then applies that the side lengths of the meshes 6 are equal to or greater than the wavelength ⁇ of the ultrasound in the flowing medium, but are preferably less than twice the wavelength ⁇ .
  • the meshes 6 of the grid 7 can also have a triangular, polygonal or star-shaped cross section. It then applies to the dimensioning of the meshes 6 that the diameter of the circle enclosed by the meshes 6 of the grating 7 is equal to the wavelength ⁇ of the flowing medium or greater than this wavelength, but is preferably less than twice the wavelength ⁇ .
  • FIGS. 4 and 5 A comparison of FIGS. 4 and 5 with FIG. 1 shows that in the ultrasonic flow meter according to the invention the vortices 4 are significantly smaller than the vortices 4 in the ultrasonic flow meter according to FIG. 1 belonging to the prior art the rest, as stated, the frequency of the vortices 4 in the ultrasonic flow meter according to the invention is substantially greater than the frequency of the vortices 1 in the known ultrasound flow meter shown in FIG. 1.
  • the time constant is significantly reduced, for example by a factor of 10
  • the measurement accuracy namely both the linearity and the reproducibility
  • the ratio of the measurement signal to the interference signal is also improved.
  • FIG. 5 shows the dependence of the measurement error on the speed of the flowing medium, on the one hand for the known ultrasonic flow meter shown in FIG. 1 and on the other hand for the flow meter according to the invention shown in FIGS. 3 and 4. It can easily be seen that, in the known flow meter, the measurement error depends strongly on the speed of the flowing medium, and is otherwise relatively large, while in the ultrasonic flow meter according to the invention, an overall extremely small one, on the speed of the flowing one There is hardly any measurement error dependent on the medium.
  • the relatively small vortices 4 which occur in the ultrasonic flow meter according to the invention not only hardly interfere with measurement technology, but also make a positive contribution to the permanent functionality of the ultrasonic flow meter according to the invention, namely to the extent that the vortices 4 lead to the mesh 7 always being cleaned, the meshes 6 of the mesh 7 thus remaining permeable to ultrasound.

Landscapes

  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Measuring Volume Flow (AREA)

Abstract

L'invention concerne un débitmètre à ultrasons pour fluides en écoulement, comportant un tube de mesure (1) et deux transducteurs à ultrasons (2) décalés l'un par rapport à l'autre dans le sens d'écoulement. Les transducteurs à ultrasons (2) sont montés dans des poches (3) du tube de mesure (1) de façon à être en contact avec le fluide en écoulement. Le dispositif de l'invention permet d'éliminer les inconvénients et les problèmes des débitmètres de la technique antérieure, dus au tourbillon (4) généré par les poches à transducteurs (3). A cet effet, les poches (3) du débitmètre à ultrasons sont pourvues côté entrée d'un treillis (7) présentant des mailles (6).
EP97927071A 1996-05-28 1997-05-28 Debitmetre a ultrasons Withdrawn EP0842400A1 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
DE19621343 1996-05-28
DE19621343 1996-05-28
DE19648784A DE19648784C2 (de) 1996-05-28 1996-11-25 Ultraschall-Durchflußmesser
DE19648784 1996-11-25
PCT/EP1997/002784 WO1997045707A1 (fr) 1996-05-28 1997-05-28 Debitmetre a ultrasons

Publications (1)

Publication Number Publication Date
EP0842400A1 true EP0842400A1 (fr) 1998-05-20

Family

ID=26026086

Family Applications (1)

Application Number Title Priority Date Filing Date
EP97927071A Withdrawn EP0842400A1 (fr) 1996-05-28 1997-05-28 Debitmetre a ultrasons

Country Status (3)

Country Link
EP (1) EP0842400A1 (fr)
JP (1) JPH11510610A (fr)
WO (1) WO1997045707A1 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1816443A3 (fr) * 1999-03-17 2013-10-30 Panasonic Corporation Débitmètre à ultrasons
JP2007071894A (ja) * 2006-12-18 2007-03-22 Matsushita Electric Ind Co Ltd 超音波式流量計測装置
JP2011112378A (ja) * 2009-11-24 2011-06-09 Panasonic Corp 流路部材および超音波式流体計測装置
JP5712358B2 (ja) 2009-11-24 2015-05-07 パナソニックＩｐマネジメント株式会社 超音波式流体計測構造および超音波式流体計測装置
DE102014103378A1 (de) 2014-03-13 2015-09-17 Krohne Messtechnik Gmbh Messanordnung zur Bestimmung und/oder Überwachung mindestens einer Messgröße eines Mediums

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2385084A1 (fr) * 1977-03-25 1978-10-20 Crouzet Sa Perfectionnement aux debitmetres a ultrasons
AT377086B (de) * 1979-07-19 1985-02-11 Friedmann Kg Alex Vorrichtung zum messen der stroemungsgeschwindigkeit eines fluids
GB2139755B (en) * 1983-05-11 1987-03-04 British Gas Corp Ultrasonic flowmeter
DE4222286C1 (de) * 1992-06-03 1994-05-11 Reutter Georg Dr Ultraschall-Spirometer
KR960013251B1 (ko) * 1993-08-25 1996-10-02 주식회사 창민물산 초음파 유량측정 방법과 장치

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9745707A1 *

Also Published As

Publication number Publication date
WO1997045707A1 (fr) 1997-12-04
JPH11510610A (ja) 1999-09-14

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