Classifications

• • 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
  • G01F1/05—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 using mechanical effects
  • G01F1/20—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 using mechanical effects by detection of dynamic effects of the flow
  • G01F1/32—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 using mechanical effects by detection of dynamic effects of the flow using swirl flowmeters
  • G01F1/3227—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 using mechanical effects by detection of dynamic effects of the flow using swirl flowmeters using fluidic oscillators
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15C—FLUID-CIRCUIT ELEMENTS PREDOMINANTLY USED FOR COMPUTING OR CONTROL PURPOSES
  • F15C1/00—Circuit elements having no moving parts
  • F15C1/22—Oscillators

Definitions

• Such devices are very sensitive to disturbances generated upstream in the flow of the fluid, for example by a valve or an elbow, such as a rotational structure of the speeds propagated by the flow and which induces highly tainted measurements. errors.
• this type of conditioner nevertheless generates turbulence downstream of said flow conditioner which disturbs the determination of the volume quantity of the fluid and it becomes clogged over time. Clogging of the conditioner inevitably leads to a reduction in its performance and to an increase in pressure losses.
• this type of conditioner must be placed far enough upstream of the measurement block, which is not without posing problems of compactness.
• This patent application describes a measuring device comprising a first large chamber in which the flow of fluid opens perpendicular to the plane of symmetry and offering to said flow a sudden increase in the passage section.
• the flow conditioner forms with the walls which surround the convergent two passages symmetrical with respect to the longitudinal plane of symmetry which consist of a first converging portion and a second diverging portion which is the seat of a flow recirculation fluid.
• Each of these passages receives a fraction of the flow of the fluid and accelerates it then slows it down before the two fractions mix and penetrate into the convergent.
• this asymmetry of the flow can still be present in the fluidic oscillator and thus modify the oscillation frequency which affects the measurement of the volume quantity of the fluid.
• the present invention thus relates to a method for conditioning a flow of a fluid from a first zone to a second zone located downstream of said first zone, characterized in that said method consists in:
• fractionation makes it possible to destroy the vortex structures present in the flow and in general, allows to control the momentum of the flow.
• the flow of the fractionated fluid is then channeled symmetrically with respect to the longitudinal direction of the flow over a determined length from the place of fractionation to the second zone. Over at least part of this determined length, the flow is accelerated symmetrically with respect to the longitudinal direction that the flow has before its fractionation in order to obtain a more homogeneous distribution of velocities in said flow fraction. It is particularly important that the split flow is channeled without being slowed down. Such a slowing down can for example occur with an increase in passage cross-section or with an obstacle on the passage of said flow.
• each fraction of the flow can be accelerated immediately downstream of the fractionation zone over a part of the determined length of the channeling step or over its entire length.
• the conditioning of the fluid according to the invention has the effect of conferring on the flow which opens into the second zone characteristics independent of those of the flow in the first zone.
• the present invention also relates to a fluid flow conditioner comprising an inlet and an outlet for the fluid flow, characterized in that said conditioner is symmetrical with respect to a longitudinal plane of symmetry (P) in which said input and output are contained and in that it comprises:
• said channeling means comprising at least one convergent portion and not slowing the flow, the distance between the inlet of the conditioner and the impact surface as well as the dimension of the section offered for flow in the means of pipe with respect to that of the inlet of said conditioner being chosen so that the flow of the fluid has a longitudinal direction up to 'to said impact surface and does not oscillate in the chamber.
• This conditioner works as described above. This conditioner makes it possible to destroy the vortex structures and to overcome the heterogeneities present in the distribution of flow velocities.
• As the flow conditioner according to the invention is symmetrical with respect to the longitudinal plane of symmetry and, due to the presence of the mixing zone, each flow fraction is subjected to a loss of approximately equal load and is therefore distributed approximately equally in each passage, which contributes to obtaining a uniform speed distribution in each flow fraction.
• the channeling means comprise at least one converging portion and do not slow down the flow to the outlet of the conditioner, that is to say that the fractionated flow is at least accelerated over part of the length of said channeling means, this makes it possible to obtain in the flow a distribution of speeds which is uniformized downstream.
• the converging portion can be connected directly to the chamber into which the flow opens, thereby increasing the speed of the fractionated flow just after its fractionation.
• the channeling means comprise a portion of constant passage section disposed downstream of the converging portion and which serves to channel each fraction of flow towards the outlet of the conditioner.
• the means for channeling the flow conditioner comprise a converging portion which is not directly connected to the chamber. This converging portion can also be added to that which is directly connected to the chamber in order to better distribute the zone of the passage over which the flow fraction is accelerated.
• the means for channeling the fractionated flow comprise at least one bend to allow in particular to orient the corresponding flow fraction towards the outlet of the conditioner.
• elbow is included in a converging portion in order to increase the compactness of the flow conditioner according to the invention.
• the channeling means may for example comprise two bends with inverted concavities or even more than two bends.
• This characteristic increases the efficiency of the flow conditioner according to the invention.
• the minimum passage section of the channeling means is at least twice the passage section of the outlet of said conditioner
• the dimension between the inlet and the outlet of said conditioner is between one and five times the passage diameter of the inlet of the conditioner
• the enclosure and the obstacle each have an interior surface and an exterior surface respectively which form between them two lateral passages surrounding the obstacle
• the obstacle is formed by a central body and by two lateral portions extending mainly in a transverse direction relative to the longitudinal plane of symmetry P from said central body,
• each lateral portion is for example in the shape of a lobe
• the convex outer surface has a circular shape with a radius R1 of between 0.1 and 3.5 times the diameter of the conditioner inlet
• each lateral portion has a concave internal surface
• the concave internal surface has a circular profile with radius R2 of between 0.3 and 4 times the diameter of the conditioner inlet
• the conditioner according to the invention can be applied to a gas as well as to water, or even to a fluid such as for example a fuel for motor vehicles.
• the invention also relates to a device for determining a volume quantity of a flowing fluid, comprising a measuring block and a flow conditioner as described above and which is arranged upstream of said measuring block with respect to in the direction of flow of the fluid.
• the measuring block is arranged in line with the flow conditioner.
• the measuring block is a fluidic oscillator
• the measurement block comprises at least one cross-section measurement channel having a parallelepiped shape and at least two ultrasonic transducers defining between them and on at least part of said measurement channel an ultrasonic measurement path.
• FIG. 1 is a schematic top view of the flow conditioner according to a first embodiment of the invention
• FIG. 2 is a schematic perspective view of the flow conditioner shown in FIG. 1 and which is arranged upstream of a prior art fluidic oscillator
• FIG. 2a is a schematic perspective view of the flow conditioner according to a first variant of the embodiment of the invention shown in FIGS. 1 and 2
• FIG. 2b illustrates the operation of the flow conditioner shown in FIG. 1,
• FIG. 3 is a schematic top view of the flow conditioner according to a second variant of the embodiment of the invention shown in FIGS. 1 and 2,
• FIG. 4 is a schematic top view of the flow conditioner according to a third variant of the embodiment of the invention shown in FIGS. 1 and 2,
• FIG. 5 is a schematic top view of the flow conditioner according to a fourth variant of the embodiment of the invention shown in Figures 1 and 2
• - Figure 6 is a schematic view along arrow A of the conditioner flow shown in Figure 5
• FIG. 7 is a schematic top view of the flow conditioner according to a second embodiment of the invention.
• FIG. 10 is a schematic top view of the flow conditioner shown in Figure 1 and on which is indicated the distribution of the velocity field of the flow when said flow at the inlet of said conditioner has a distribution profile of heterogeneous speeds,
• FIG. 11 shows two calibration curves (0, +) obtained from a gas meter comprising a fluidic oscillator as shown in Figure 2, without the flow conditioner according to the invention, these curves being respectively obtained when the flow has the profile shown in FIG. 9 and that shown in FIG. 10,
• - Figure 12 shows two calibration curves (0, +) obtained from the gas meter comprising a fluidic oscillator as shown in Figure 2 with the flow conditioner according to the invention and for the flow profiles respectively shown in Figure 9 and Figure 10.
• a fluid flow conditioner 10 comprises an inlet 12 and an outlet 14 for said flow.
• the output 14 of the conditioner 10 is connected downstream to a device for determining a volume quantity of the fluid comprising a measurement block 2 which is in the form of a fluidic oscillator as for example described in the French patent application. no.9205301.
• inlet whose passage section gives the flow a two-dimensional character and has a shape, for example rectangular.
• the outlet 14 is a slot whose passage section is rectangular in shape and which gives the flow a two-dimensional character.
• the fluidic oscillator is also symmetrical with respect to the plane of symmetry P, which makes it possible to preserve the characteristics of the flow of the fluid thus conditioned without adding additional disturbances such as those caused by an elbow which would be placed between the outlet of the conditioner and the fluidic oscillator.
• the conditioner 10 also comprises an enclosure 16 which connects the inlet 12 and the outlet 14 as well as an obstacle 18 disposed in the middle of said enclosure between the inlet and the outlet.
• a chamber 20 connected to the inlet 12 is provided in the enclosure 16 to receive the flow of the fluid coming from said inlet.
• the obstacle 18 is formed by a central body 22 having a front surface 22a perpendicular to the longitudinal plane of symmetry P and located opposite the inlet 12 in a transverse plane P1.
• the front surface 22a of the obstacle 18 is perpendicular to the longitudinal direction of the flow defined by the inlet 12 and is called the impact surface
• This impact surface 22a is flat, but it should however be noted that said surface can for example be slightly concave or convex without thereby affecting the efficiency of the flow conditioner 10.
• the chamber 20 is defined between the inlet 12 and the front surface 22a of the obstacle 18.
• the enclosure 16 has an interior surface 16a and the obstacle 18 has an exterior surface 23, these two surfaces forming between them two symmetrical passages 28, 30 which surround said obstacle and bring the chamber 20 into communication with outlet 14 from flow conditioner 10.
• the flow of the fluid enters the chamber 20 in a longitudinal direction being subjected to a sudden increase in the section passage which gives rise to a symmetrical recirculation phenomenon denoted A, B on either side of the inlet 12, in each of the converging portions 28a, 30a of the passages 28.30.
• the flow of the fluid then strikes the impact surface 22a perpendicular to it and splits on said impact surface, transforming the longitudinal direction of the average speed of said flow into transverse components. Due to the principle of conservation of the momentum, the flow thus split will be redistributed in all the transverse directions which are offered to it, thus breaking any existing flow structure at the inlet of the conditioner.
• the two flow fractions each borrows in a substantially symmetrical manner one of the converging portions 28a, 30a of the respective passages 28, 30 and come into contact with the corresponding flow recirculation A, B.
• the convergent portions have the function, on the one hand, of stabilizing the flow recirculation and, on the other hand, of homogenizing the velocity field of the fluid flow.
• Each flow fraction borrows a first bend 17 or 19 and is then channeled towards the mixing zone 32 by the portion 28b or 30b of constant passage section of the corresponding passage 28 or 30.
• the mixing zone 32 has sufficiently small dimensions to accelerate the flow and thus improve its homogeneity at the outlet 14 of the flow conditioning 10. Thus, the characteristics of the flow at the outlet 14 of the conditioner 10 are independent of the characteristics of the flow at the inlet 12.
• the conditioner according to the invention can also take the form of the variant represented in FIGS. 5 and 6 where only the modified elements bear new references compared to FIGS. 1 and 2.
• the inlet 11 and the outlet 14 are offset by 90 ° in the longitudinal plane of symmetry P.
• the inlet 11 of the flow conditioner defines a longitudinal direction for the flow opening into the chamber 20 of the enclosure 16 which is parallel to the direction defined by the front surface 22a of the obstacle 18.
• the inlet 11 is of axisymmetric and for example circular shape while the outlet 14 is a slot which gives the flow a two-dimensional character.
• the first embodiment (fig. 1 and 2) of the flow conditioner according to the invention can also be applied upstream of a device for determining a volume quantity of fluid comprising an ultrasonic measurement block.
• Such a measurement block comprises, for example, a cross-section measurement channel having a parallelepiped shape, for example rectangular, the slot-shaped output of said conditioner corresponding to the input of this channel.
• Two ultrasonic transducers are mounted on one of the walls of the measurement channel or on two opposite walls of this channel so as to define between them and on at least part of said measurement channel an ultrasonic measurement path.
• the international patent application WO9109282 describes this type of device with an ultrasonic measuring block.
• the inlet 1 12 and the outlet 1 14 of the flow conditioner 1 10 are aligned in the longitudinal direction of the flow which is defined by the direction that said inlet gives to said flow.
• the inlet 112 and the outlet 114 have an axisymmetric shape, for example circular.
• the flow conditioner 110 comprises an enclosure 1 16 connecting the inlet 112 and the outlet 114 as well as an obstacle 118 placed in the middle of said enclosure and which is provided with a front surface 122a at least partially forming the impact surface of said conditioner.
• a chamber 120 connected to the inlet 112 of the conditioner is provided in the enclosure 116 to receive the flow of the fluid emerging in the longitudinal direction.
• the obstacle 118 is formed by a central body 122 having the front surface 122a perpendicular to the longitudinal plane of symmetry P and located opposite the inlet 112 in a transverse plane P1.
• the chamber 120 is defined between the inlet 112 and the front surface 122a of the obstacle 1 18.
• the front surface 122a of the obstacle 118 is perpendicular to the longitudinal direction of the flow defined by the inlet 112.
• the flow conditioner has a symmetry of revolution around the longitudinal direction of the flow of the fluid.
• two elements 127,129 are fixed between the inner surface 1 16a of the enclosure 1 16 and the surface exterior 123 of the obstacle 118 so as to separate over a part of its length the single passage into two passages 128,130 of the same dimensions and the length of which is that of said elements.
• These elements 127, 129 are for example in the form of flat plates as thin as possible so as not to disturb the flow and whose largest surface is arranged parallel to said flow. It is possible to give the plates 127, 129 the length as well as the desired location between the two surfaces 116a and 123, but it is not necessary, however, to arrange them immediately downstream of the chamber 120.
• the fractionated flow on the impact surface 122a must be distributed in a substantially identical manner in a portion of upstream common passage 125 in all the transverse directions which are offered to it over a sufficient length before being channeled, this in order to to avoid the propagation of vortex structures downstream of the conditioner.
• the obstacle 118 is also formed of a peripheral portion 131 having for example the shape of a flange surrounding the central body.
• the flange 131 defines with the part of the enclosure 116 opposite a first bend 117 for the fractionated flow as well as a converging portion directly connected to the chamber 120 and including said bend.
• the plate-shaped elements 127 and 129 are for example located in the first bend 117 downstream of the common passage portion 125.
• the central body 122 of the obstacle 118 has a rear portion 122b which defines with the part of the enclosure 116 opposite a second bend 133 for the fractional flow.
• the rear portion 122b of the obstacle 118 has for example a conical shape, the point of which is situated opposite the outlet 114 of the conditioner 110. Except for the fact that the passages for the fractionated flow are not defined immediately downstream of the chamber 120. After the fractionation of the flow of longitudinal direction, but after a certain length over which the fractionated flow borrows a portion of passage ses125, the process for conditioning the fluid according to the invention is not modified compared to what has been described above.
• fractionated flow After the fractionated flow has been channeled in the upstream common passage portion 125 and in the passages 128, 130 defined by the plate-shaped elements 127,129, said fractionated flow joins a downstream common passage portion 132 playing the role of mixing zone and the passage section of which is for example continuously decreasing up to the outlet 114.
• the length of the plate-shaped elements 127,129 can be greater than that indicated in FIG. 7 and thus the common passage portion 132 can be reduced to an area of small dimensions such as that described with reference in Figures 1 and 2 and represented by the reference 32.
• This configuration of revolution is particularly well suited to devices for determining a volume quantity of fluid comprising an ultrasonic measurement block produced in the form of a conduit whose cross section is of axisymmetric shape.
• the measurement conduit is equipped with two ultrasonic transducers arranged opposite one another at the two opposite ends of said conduit, one of said transducers can for example be arranged in the rear part of the obstacle 118 of the conditioner in order to do not disturb the flow once it has been conditioned.
• Figures 9 and 10 show the distribution of the flow velocity field in the flow conditioner shown in Figures 1 and 2, thus reflecting the efficiency of said flow conditioner.
• the flow of the fluid at the inlet 12 of the flow conditioner shown in FIG. 10 has undergone a severe disturbance since the part of the duct situated upstream of said inlet has been obstructed on one half to reproduce the '' one of the tests provided for by the OIML (International Organization of Legal Metrology) standard R32.
• OIML International Organization of Legal Metrology
• said flow is distributed in a substantially symmetrical manner in each passage 28.30 and the two flow fractions become very rapidly more and more symmetrical with each other as they progress in their respective passage.
• the reconstituted flow has a velocity distribution which is homogeneous and which has substantially the same characteristics as the flow at the outlet of the conditioner of FIG. 9.
• the flow conditioner according to the invention reproduces at its output flow characteristics independent of the characteristics of the flow at the input of said conditioner.
• Figures 11 and 12 are two graphs which each represent two calibration curves (these curves reflect the error made in the measurement of the air flow as a function of the flow) of a gas meter which includes a fluidic oscillator as shown in FIG. 2 according to the two different flow profiles indicated at the inlet of the conditioner in FIGS. 9 and 10.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Theoretical Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Physics & Mathematics (AREA)
• Measuring Volume Flow (AREA)
• Air-Flow Control Members (AREA)
• Lift Valve (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=9475934

Family Applications (1)

Country Status (10)

Cited By (2)

Families Citing this family (3)

Citations (7)

Family Cites Families (2)

• 1995
  • 1995-02-06 FR FR9501425A patent/FR2730278B1/fr not_active Expired - Fee Related
• 1996
  • 1996-01-30 WO PCT/FR1996/000160 patent/WO1996024774A1/fr not_active Ceased
  • 1996-01-30 RU RU97114952/06A patent/RU2154202C2/ru active
  • 1996-01-30 DK DK96902313T patent/DK0808425T3/da active
  • 1996-01-30 DE DE69601215T patent/DE69601215T2/de not_active Expired - Lifetime
  • 1996-01-30 UA UA97084116A patent/UA34499C2/uk unknown
  • 1996-01-30 EP EP96902313A patent/EP0808425B1/fr not_active Expired - Lifetime
  • 1996-01-30 ES ES96902313T patent/ES2127621T3/es not_active Expired - Lifetime
  • 1996-01-31 TW TW085101205A patent/TW295638B/zh active
  • 1996-02-07 AR AR33532596A patent/AR001080A1/es not_active Application Discontinuation

Patent Citations (7)

Also Published As

Similar Documents

Legal Events