FR2644527A1 - METHOD AND DEVICE FOR STRAIGHTENING A PERTURBED FLOW - Google Patents

Abstract

The device comprises a flow rectifier 2 provided with a central body 6 provided over its entire periphery with a number of radial walls 7. The latter form elongated sections, evolving in a straight line and ensuring the formation of parallel partial currents. The speed of the fluid in partial streams is markedly higher than that in disturbed flow. This results in a regularization of the speed profile and, due to the distribution of the fluid over several parallel streams, a regularization of the turbulence with a reduced pressure drop. In addition, a short length of tubing is sufficient to straighten the disturbed flow.

Description

i Method and device for rectifying a disturbed flow

  The invention relates to a method for

  set up the disturbed flow of a fluid by distributing this disturbed flow over several straight partial, elongated and substantially parallel streams, the speed of the fluid in the partial streams being higher than

  in the disturbed flow zone.

  This type of process is used to straighten the disturbed flow of a fluid, for example a liquid or a gas, before the entry of this fluid into an organ.

  strangulation. This body is generally an apparatus

  reil to measure the flow, such as a diaphragm volume gauge, or a turbine or vortex meter. The accuracy of the flow measurement depends on the quality of the rectification, the object being to place the meter as close as possible downstream of the last disturbing element of

  the flow, for example downstream of the last bend. The lon-

  straight feeder required for flow straightening

  should be as short as possible.

  It has been observed that the procedures employed to date meeting the length constraints have left

  to be desired as to the quality of the recovery obtained.

  The main object of the present invention is

  purpose of providing a process of the aforementioned type, does not require

  just a short straight length to get a re-

improved training.

  According to the invention, this object is achieved by a

  process which foresees that the speed of the fluid in the

  partial rants is at least 1.2 times and preferably

  more than 1.8 times higher than in the flow area-

mentally disturbed.

  The method according to the invention exploits the con-

  birth that a considerable increase in the speed of a fluid makes it possible to largely regularize the profile of

  speed, irregular by nature due to the disturbance

  tion of the flow. In the processes known hitherto, however, attempts have been made to reduce the sum of the sections crossed by the different partial currents as little as possible with respect to the disturbed flow section. In the case of the process according to

  the invention it was possible to observe that the increase

  tion of the speed allows the desired effect to be achieved without producing high pressure drops. At the same time, the elongated partial currents provide turbulence regulation. The method according to the invention is therefore able to ensure optimal recovery of a flow

  disturbed over a short straight length.

  The process according to the invention offers the possibility of

  lity to divide the disturbed current into a relati-

  important part currents of which each individual section is comparatively narrow. It is however more advantageous to limit the number of partial currents

  to what is necessary to obtain the turbu-

  lence desired and thus retain individual sections

  comparatively large dual, since this arrangement significantly reduces pressure losses.

  Whatever solution is adopted, a re-

  particularly advantageous training is obtained because

  that the partial currents pass through a section of re-

  smaller upstream than the disturbed flow upstream section. The different partial currents pass to very

  short distance from each other, which allows

minimize pressure losses.

  The rectifier section can have any

  what form. Preferably, a form ex-

  similar to that of the disturbed flow pipe

  which, as a rule, is circular. The section of re-

  blocker can completely fill the surface of the pipe or have an annular shape whose periphery can be

  smaller or larger than that of the per-

turbid.

  The process according to the invention offers the possibility of

  lity to bring the partial currents directly in the flowmeter. It may however be more advantageous to pass the fluid leaving the rectifier into currents

  partial by a wider section than that of the rectifier

  defined by the pipe through which the

fluid.

  It has been found that the slowing down of the e-

  flow thus produced hardly affects the straightening obtained, even if from an annular section the fluid passes into a circular section, which offers optimal conditions for the use of the invention in connection

with a diaphragm flow meter.

  In addition, provision should be made for an increase

  the speed of the fluid before its distribution in terms of

  partial rants, which is another way of minimizing the pressure drop, especially when the speed of the fluid is not

  accelerated only at most up to the speed of the

  partial rants, i.e. when after distribution

  on the different partial currents the speed of the fluid

is not slowed down.

  The present invention also relates to a device for rectifying the disturbed flow of a fluid, provided with an upstream channel delimiting a section with disturbed flow, followed by a rectifier traversed by the fluid at the outlet of the upstream channel, delimited rectifier

  by a section subdivided into several essential sections

  tial parallel by several substantially parallel and elongated walls to promote the formation of straight partial currents especially for application

of the process described above.

  To optimize the straightening effect over a short straight length while minimizing pressure losses, the straightening section is smaller than

  that of the disturbed flow zone and this advantageous-

  lie at least 1.2 times but preferably more than 1.8 times. The use of walls as thin as possible makes it possible to accelerate the speed of the fluid and to regularize the speed profile without pressure losses

too high.

  The device according to the invention is also

  with a channel traversed by the fluid downstream of the rectifier

  seur, channel with a section larger than that of the rectifier

  which slows the fluid downstream of the rectifier but without significantly reducing the rectification effect obtained. The rectified flow section can therefore be easily adapted to all measuring devices, if the partial currents do not directly access the meter.

  The section of the rectifier can be selected

  as needed. It is particularly advantageous to choose an annular shape which generally has a circular contour, which allows the distribution of the fluid.

  with disturbed flow from the center to the outer zones

  res. To this end, the rectifier according to the invention is provided with a central body, projecting into the upstream channel through which the fluid with disturbed flow passes. This body

  central advantageously causes acceleration of life

  already before the distribution into partial currents and

  this by optimizing the flow, especially if the body

  - tral has a rounded tip on the upstream side.

  It is also advantageous to narrow the pa-

  external king of the rectifier compared to that of the channel

  upstream, regardless of whether the section of the

  either circular or annular blocker.

  Finally, the present invention relates to a re-

  trainer particularly suitable for operating with the

  positive described above. This rectifier comprises a central body of which at least the upstream end is closed and which is provided, distributed over its entire periphery, with a number

  radial, elongated and essentially parallel walls

  them in the direction of flow and whose downstream end is provided with a flange. Such a rectifier can be introduced

  the flowing fluid flows through the pipe

  turbated and connected with this pipe providing the aforementioned advantages. It is advantageous that on the upstream side the central body exceeds the walls and that its upstream end is provided with a rounded tip. The downstream end can

  remain open but preferably be closed.

  Other features and benefits of

  the invention will emerge more clearly from the description

  tion below of drawings annexed by way of example:

  Figure 1 shows a longitudinal section

  nale of a device according to a first embodiment

  tion of the invention, practiced along line II of Figure 2, Figure 2 shows a section along line II-II of Figure 1, Figure 3 shows a longitudinal section of a device along a second embodiment of the invention, practiced along the line III-III of Figure 4, Figure 4 shows a section along

line IV-IV of figure 3.

  The device shown in Figures 1 and 2

  comprises a channel 1 for passage of a disturbed flow.

  Channel 1 is followed by a rectifier 2, the downstream end of which is connected to a channel 3. Channel 3 leads to a

  Throttling device in the form of a flowmeter not

shown on the sketch.

  As can be seen from Figure 1, the

  sor 2 has a smaller diameter than that of channels 1 and

  3 and therefore a smaller section.

  FIG. 2 shows that the section of the rectifier is divided into a number of sections 4 ensuring the formation of straight partial currents and al-

  lanes evolving in parallel, thanks to a grid

  both thin walls 5 arranged at an angle

  right to each other.

  The speed of the partial currents passing through sections 4 is higher than that of the fluid in

  channels 1 and 3, which makes it possible to obtain, in addition to the uniform

  setting of turbulence di to fluid distribution

  on several partial currents, also, on a dis-

  very short tance, a regularization of the life profile

  tesse while limiting pressure losses to a minimum. The

  fluid is accelerated before entering sections 4.

  In the execution example illustrated by

  Figures 3 and 4, the rectifier 2 has the same contours ex-

  than channel 1 with disturbed flow. The redres-

  sor 2 has a central body 6 provided with a number of radial and elongated walls 7. These walls form with the channel wall and the central body 6 the sections 4

  crossed by partial currents. In the example re-

  presented, the section of the rectifier is therefore annular.

  The upstream face of the central body 6 projects beyond the walls 7 with a rounded point end 8. Its downstream end is provided with a flange 9 to ensure its

  fixing and allow the walls to be inserted 7.

  The different partial currents are joined

  hinder downstream of the rectifier 2 which decreases the

  speed without reducing the quality of the straightener

  ment obtained. This arrangement provides optimal conditions for mounting a diaphragm in channel 3 for

measure the fluid flow.

  According to an embodiment not shown,

  sections 4 dividing the fluid into partial currents may

  They can also be formed by tubes placed side by side to fill the section of the rectifier. In addition, the annular section may have an outer contour

  enlarging or decreasing the section of the rectifier compared to

  port to that of the upstream flow passage channel

  disturbed. The downstream end of the central body can be or

  green. If necessary the flow meter can be connected not

  on channel 3 but directly on rectifier 2.

  The invention is not limited to the embodiments-represented or described, but also encompasses

all constructive variants.

Claims (15)

  1.- Method to straighten the flow per-   turbid with a fluid in a pipe by distributing the flow   ment on several partial currents, straight, elongated, essentially parallel, the speed of the fluid in the   partial currents being higher than in the area of e-   disturbed flow, characterized in that the vi-   tesse of the fluid in the partial streams is at least 1.2 times and preferably more than 1.8 times higher than   in the disturbed flow zone.   2.- Method according to claim 1, charac-   terrified by the fact that the partial currents enter a rectifier with a smaller section than that of the disturbed flow pipe.   3.- Method according to claim 2, charac-   terrified by the fact that on leaving the rectifier device, the fluid with rectified flow passes through a pipe to   section larger than that of the rectifier device.   4.- Method according to any one of the claims   cations 1 to 3, characterized in that before its repair-   tition in several partial currents, the fluid is acces- léré.   5.- Method according to claim 4, charac-   terrified by the fact that the accelerated speed of the fluid is   at most equal to that of the fluid distributed over the partial rants.   6.- Device for the recovery of the   disturbed flow of a fluid, comprising an upstream channel (1) delimiting a disturbed flow section, followed by a rectifier (2) traversed by the fluid at the outlet of the   upstream channel, rectifier delimited by a subdivision section   sée in several partial sections (4), by several walls (5, 7) essentially parallel and elongated to favor the formation of straight partial currents,   characterized in that the cross section of the rectifier is less   higher than that of the disturbed flow.   7.- Device according to claim 6, charac-   terrified by the fact that the section of the rectifier is at least 1.2 times but preferably more than 1.8 times more   small queiasection of passage of disturbed flow.   8.- Device according to any one of the re-   vendications 6 or 7, characterized in that the re-   blocker (2) is followed by a downstream channel (3), crossed by the fluid, delimiting a section larger than that rectifier.   9.- Device according to any one of the re-   vendications 6 to 8, characterized in that the section   rectifier is annular in shape.   10.- Device according to claim 9, ca-   characterized by the fact that the rectifier (2) is provided with a central body (6) projecting into the upstream channel (1) facing the disturbed flow.   11.- Device according to claim 10, ca-   characterized by the fact that the central body (6) is provided   with a rounded point (8) on the upstream side.   12.- Device according to any one of the re-   Vendications 6 to 11, characterized in that the outer wall of the rectifier (2) is narrowed relative to that of the upstream channel (1) serving as a passage for the disturbed flow. 13.- Rectifier for a disturbed flow of a fluid, characterized by the presence of a central body (6) of which at least the upstream end is closed and which is   provided over its entire periphery with a number of radiant walls   dials (7) elongated essentially parallel to the direction of   the flow, and at its downstream end of a flange (9).   14.- Rectifier according to claim 13, ca-   characterized by the fact that on the upstream side the central body   (6) projects from the walls (7).   15.- Rectifier according to claim 14, ca-   characterized by the fact that the central body (6) is provided   on the upstream side of a rounded point (8).