JP4424936B2 - Uniform flow rate structure and flow rate measuring device in flow path - Google Patents

Description

  The present invention relates to a homogenization structure for uniformly flowing a fluid such as gas or water in a flow path, and an ultrasonic flow measuring device using the homogenization structure.

Conventionally, as an apparatus for measuring the flow rate of a rectangular flow path, there is an apparatus using ultrasonic waves (see, for example, Patent Document 1).
As shown in FIGS. 7 and 8, this ultrasonic flow measuring device has an ultrasonic transmission / reception unit 52 (on the left and right side walls 51 a of a tubular body 51 having a rectangular cross section for measuring the fluid flow velocity. 52A, 52B), and the flow rate of the fluid is measured based on the propagation time of the ultrasonic waves detected by the ultrasonic transmission / reception units 52A, 52B, and the flow rate of the fluid flowing in the tubular body 51 is calculated from the flow velocity. The flow rate calculation unit 53 is provided.

In addition, the measurement flow path portion K of the tube body 51 in which the ultrasonic transmission / reception unit 52 is disposed has a height parallel to the flow R and height in order to enhance the two-dimensionality of the flow velocity distribution of the fluid flowing in the tube body 51. Two partition plates 54 are arranged at equal intervals in the direction. As shown in FIGS. 7 and 8, a tertiary having a parabolic distribution (used in the sense of being close to a parabola, and the same shall apply hereinafter) in the height direction and the depth direction on the upstream side of the measurement flow path portion K. The flow having the original flow velocity distribution P61 is divided into three at the measurement flow path section K, that is, the flow in the depth direction is flattened by dividing the flow from the small aspect ratio into the large aspect ratio. It becomes. As described above, by arranging the partition plate 54, the two-dimensionality of the flow in the measurement flow path section K is enhanced, and the ultrasonic transmission / reception section 52 is easily included in the entire flow velocity distribution. The accuracy is improved.
JP 9-43015 A; pages 2 [0003] to pages 3 [0019]

  However, according to the above-described conventional configuration, the position of the front end edge, which is the upstream end of each partition plate 54, is set to the same position with respect to the flow. Since the flow velocity distribution (the magnitude of the velocity, for example, the average flow velocity) P62 in each divided flow path P62 is different, that is, the flow rate of the fluid flowing through each divided flow path is not uniform, the absolute value of the measured flow velocity is There was a problem that it deviated greatly from the true average flow velocity.

  Accordingly, the present invention solves the above-described problem, and a flow rate equalization structure in a flow channel in which the flow rate of a fluid flowing through each divided flow channel divided by a partition plate becomes more uniform, and the flow rate uniformization An object of the present invention is to provide an ultrasonic flow rate measuring device capable of improving the flow rate measurement accuracy using the structure.

In order to achieve the above object, the flow rate equalization structure in the flow channel according to claim 1 of the present invention divides the flow channel cross-sectional area evenly in parallel with the flow into the rectangular flow channel. Arrange the first partition as
The second partition plate is disposed in the divided flow path divided by the first partition plate in parallel with the flow and so as to divide the divided pipe cross-sectional area equally, and the upstream end of the second partition plate Is positioned downstream of the upstream end of the first partition plate,
A turbulent flow promoting portion is provided on the channel wall surface on the upstream side of the first partition plate and on the split channel wall surface on the upstream side of the second partition plate.

According to this flow equalization structure, a turbulent flow promoting portion is arranged on the wall surface of the flow channel upstream of the partition plate that divides the flow channel to promote turbulent flow. In addition, in the portion other than the vicinity of the wall surface, the center having a gentle velocity gradient as a whole has a slightly flat flow velocity distribution, so that the flow rate in each flow path divided by the partition plate can be made uniform.

In particular, the channel cross-section is divided into two stages from the large divided flow channel to the small divided flow channel by the partition plate, and the turbulence promoting portions are respectively formed on the wall surfaces of the upstream flow channels to these divided flow channels. than placing the, in the portion other than the near-wall in the small split flow channel, the center becomes more flat flow velocity distribution with moderate velocity gradient as a whole, thus further obtaining achieving uniform flow rate in the subdivision passage .

Furthermore, ultrasonic type flow measuring device according to claim 2, in the middle of the channel having a flow equalizing structure according to claim 1, together with a direction crossing the flow path to place the transmission and reception of ultrasonic waves ,
A flow rate calculation unit that calculates the flow rate of the fluid flowing through the flow path based on the propagation time of the ultrasonic wave in the ultrasonic transmission / reception unit is provided.

According to this flow rate measuring device, since the ultrasonic transmission / reception unit is arranged in the portion related to the flow rate equalizing structure according to claim 1 to measure the flow rate flowing through the divided flow path, the flow rate of the fluid is further increased. It can be measured accurately.

As described above, according to the flow equalization structure according to the first aspect of the present invention, the turbulent flow promoting portion is arranged on the wall surface of the flow channel on the upstream side of the partition plate dividing the flow channel so as to promote the turbulent flow. Therefore, in the portion other than the vicinity of the wall surface, the center having a gentle velocity gradient as a whole has a slightly flat flow velocity distribution, so that the flow rate in each flow path divided by the partition plate can be made uniform.

In particular, the flow path cross section is divided into two stages from the large divided flow path to the small divided flow path by the first partition plate and the second partition plate disposed downstream thereof , and the wall surface of the upstream side of the flow channel, in each of arranging the turbulence promoting portion, the portion other than the near-wall in the small split flow channel, the center becomes more flat flow velocity distribution with moderate velocity gradient as a whole, thus The flow rate in the small divided flow path can be made more uniform.

Furthermore, according to the flow rate measuring device according to claim 2 , since the ultrasonic transmission / reception unit is arranged in the portion related to the flow rate equalizing structure according to claim 1 , the flow rate flowing through the divided flow path is measured. The flow rate of the fluid can be measured more accurately.

Hereinafter, a flow rate uniformizing structure in a flow channel according to an embodiment of the present invention will be described with reference to the drawings . First, a basic configuration according to the flow uniformizing structure of the present invention will be described.
[Basic configuration]
FIG. 1 and FIG. 2 are cross-sectional views showing a flow path homogenizing structure and a flow velocity distribution in the basic configuration of the present invention .

As a tubular body (which is also a flow path and a pipeline) 1 for flowing a fluid (for example, gas, water, etc.) according to this basic configuration, one having a rectangular cross section is used.
That is, the tubular body 1 is composed of left and right side plates 2, and an upper plate 3 and a lower plate (bottom plate) 4 disposed above and below the both side plates 2 and 2, for example, wider than the height. Has been.

  And in this pipe body 1, the partition plate 5 of predetermined length is arrange | positioned in the direction along the flow R at equal intervals in the height direction (it may be 1 sheet or 3 sheets or more). . In other words, the channel cross-sectional area in the tube body 1 is divided into three equal parts in the height direction, and three divided channels S (also referred to as multilayer channel portions) are formed.

Furthermore, turbulent flow promoting members (turbulent flow promoting portions) 6 are provided above and below the inner wall surface 1a of the tubular body 1 at a position slightly upstream from these partition plates 5.
As the turbulent flow promoting member 6, for example, a sandpaper having a rough surface is used, and is pasted along the upper and lower sides of the inner wall surface 1a (the inner surfaces of the upper plate 3 and the lower plate 4) with a predetermined width. ing.

  In this configuration, the flow having a parabolic flow velocity distribution P11 having a large velocity gradient on the upstream side is promoted by the turbulent flow promoting member 6, and therefore, as a whole, a gentle velocity gradient is provided in portions other than the vicinity of the wall surface. The flow rate distribution P12 near the trapezoidal shape is changed to a substantially flat trapezoidal shape at the center, and the flow of the flow velocity distribution close to the trapezoidal shape is divided by the partition plate 5. Is planned. In addition, P13 shows the flow-velocity distribution in each division | segmentation flow path S in the figure.

  That is, when a plurality of partition plates 5 are arranged in the tubular body 1 and the flow rate flowing through the tubular body 1 is equally divided, the flow is disturbed by the turbulence promoting member 6 disposed on the upstream side thereof. Since the flow velocity is promoted to flow and the flow velocity distribution in the central portion excluding the vicinity of the wall surface is made flat, it is possible to equalize the flow rate passing through each divided flow path S partitioned by the partition plate 6. it can. In addition, when the wall surface roughness scale is larger than the viscous bottom layer thickness, it is known that the flow velocity distribution P12 has universality. Therefore, when the flow is divided by the partition plate 5, the flow distribution can be easily controlled. It becomes.

  Further, since the flow whose flow velocity distribution is made flat by the turbulent flow promoting member 6 is divided by the partition plate 5, the partition plate 5 is slightly shifted up and down in the tube 1 due to an assembly error or the like. Even in the case of the arrangement, the difference in the flow rate flowing through each divided flow path S does not increase, and therefore the design tolerance of the position of the partition plate 5 can be loosened (sweetened).

In the basic configuration described above , the turbulent flow promoting members 6 are installed on the upper surface and the lower surface of the inner wall surface, but may be provided on both side surfaces and in the height direction (for example, at reference numeral 7 in FIG. 1). Show).

[Embodiment 1]
3 and 4 show the flow channel homogenization structure and flow velocity distribution according to Embodiment 1 of the present invention based on the basic configuration described above .

The tubular body (which is also a flow path and a pipeline) through which a fluid (for example, gas, water, etc.) according to the first embodiment is used has a rectangular cross section as in the basic configuration described above. The flow path is divided into two stages from large to small.

  That is, the tubular body 11 is composed of left and right side plates 12, and an upper plate 13 and a lower plate (bottom plate) 14 disposed above and below the both side plates 12 and 12, for example, wider than the height. Has been.

  In the tubular body 11, the first partition plate 15 having a predetermined length is disposed at the center position in the height direction to form two large divided flow paths S1 up and down, and each of the large divided flow paths S1. However, the second partition plate 16 disposed at a position downstream of the first partition plate 15 by a predetermined distance and at the center in the height direction of each of the large divided flow channel portions S1 has two small divided flow channels vertically. Divided into part S2. In addition, although the 2nd partition plate 16 is arrange | positioned in the downstream of the flow R rather than the 1st partition plate 15, the rear-end edge which is the downstream end is made into the same position.

  Furthermore, a first turbulent flow promoting member (turbulent flow promoting portion) 17 is provided above and below the inner wall surface 11a at a position upstream from the front edge that is the upstream end of the first partition plate 15, and a second partition is provided. A second turbulent flow promoting member (turbulent flow promoting portion) 18 is provided on the inner wall surface 11a and the wall surface 15a on the upstream side of the front edge that is the upstream end of the plate 16.

  As these turbulent flow promoting members 17 and 18, for example, sandpaper having a rough surface is used, and the inner wall surface 11 a and the upper and lower wall surfaces 15 a of the first partition plate 15 (hereinafter referred to as the inner wall surface and the wall surface) have a predetermined width. Is referred to as a wall surface or the like).

  In this configuration, the flow having the parabolic flow velocity distribution P21 having a large velocity gradient on the upstream side is promoted by the first turbulence promoting member 17 and is gentle as a whole in portions other than the vicinity of the wall surface. The flow velocity distribution P22 has a velocity gradient and the center changes to a slightly flat trapezoidal shape, and the flow of the flow velocity distribution close to the trapezoidal shape is equally divided vertically by the first partition plate 15, and the second disturbance The flow promoting member 18 further promotes the turbulent flow in each of the small divided flow paths S2. Again, the portion other than the vicinity of the wall surface has a gentler velocity gradient as a whole and a trapezoidal flow velocity distribution with a flatter center. After changing to P23, it is further divided equally up and down by the second partition plate 16, respectively. In the figure, P24 indicates the flow velocity distribution in each small divided flow path S2.

That is, the flow in the tube body 11 is roughly divided into two parts by the first partition plate 15 and then divided into two parts, and the upstream side of the large and small divided flow paths S1 and S2 is turbulent. Since the flow promoting members 17 and 18 are provided, the flow rate in the tube 1 can be made more uniform than that described in the basic configuration .

In the first embodiment as well, as described in the basic configuration described above, the turbulence promoting members 17 and 18 are installed on the upper and lower surfaces of the wall surface or the like, but on both sides and in the height direction. It may be provided.

In the first embodiment , the turbulent flow promoting member is made of sandpaper pasted on the wall surface. However, the wall surface 1a, 11a, 15a is sandblasted or the like with a roughness corresponding to the same roughness scale. It may be roughened by the means. In this case, this rough wall surface portion becomes a turbulent flow promoting portion.

  In addition, a wire mesh capable of exhibiting a roughness function corresponding to the same roughness scale is attached to the inner wall surface, or a wire having a diameter corresponding to the same roughness scale has an axial direction orthogonal to the flow direction R1. As shown, it may be arranged on the wall surfaces 1a, 11a, 15a.

Further, a fine cylinder having a height corresponding to the same roughness scale may be erected vertically on the wall surfaces 1a, 11a, and 15a such that the axial direction is perpendicular to the flow direction R1. .
Further, fine uneven portions having a height corresponding to the same roughness scale may be formed on the wall surfaces 1a, 11a, and 15a with striped members extending in the flow direction R.

Further, in FIGS. 3 and 4 (the same applies to FIGS. 1 and 2) , the turbulence promoting members 6, 17 and 18 are illustrated as having a finite length along the flow direction R. It can also be provided on the entire surface of 11a, 15a.

Next, a flow rate measuring device in a flow channel according to an embodiment of the present invention will be described with reference to the drawings.
The flow rate measuring apparatus described below uses the above-described flow rate uniforming structure in the flow channel, and measures the flow rate in the flow channel in the flow rate uniforming structure using ultrasonic waves. Accordingly, the flow rate uniform structure is the same as that described in the basic configuration and the first embodiment, and therefore, the same reference numerals are used and detailed description thereof is omitted.

[Flow measurement device according to basic configuration]
The flow rate measuring device according to the basic configuration of the present invention uses the flow rate uniformizing structure of the pipe line according to the basic configuration described above, and examples of the fluid to be measured include gas and water.

That is, as shown in FIG. 5, the flow rate measuring device 21 includes the flow rate uniformizing structure described in the basic configuration described above, that is, the divided flow path S in which the turbulent flow promoting member 6 is provided on the upstream side. A pair of ultrasonic transmission / reception units (ultrasonic vibration) each having a tubular section 22 having a rectangular cross section and left and right side plates 2 forming the outer wall of the tubular section 22 via cylindrical mounting members 23. 24 (24A, 24B) and the ultrasonic wave transmission time (also referred to as transmission time or arrival time) between the ultrasonic wave transmitting / receiving unit 24 and the flow velocity were obtained based on the propagation time. Thereafter, the flow rate calculation unit 25 calculates the flow rate of the fluid based on the flow velocity. The ultrasonic transmission / reception unit 24 is attached at a position where the ultrasonic wave crosses the middle part of the divided flow path S.

  In the flow rate calculation unit 25, the flow velocity in the divided flow path (also referred to as an ultrasonic measurement region) S and the average in the pipe body (flow path) 1 are previously determined according to various flows of the fluid to be measured. The relationship with the flow velocity is stored as a correction coefficient, and the average flow velocity in the tube 1 is obtained from the measured flow velocity using the correction coefficient.

  Note that the ultrasonic transmitting / receiving units 24A and 24B are attached to the flow direction R in a horizontal plane at a predetermined angle θ (however, 0 ° <θ <90 °, but preferably close to 0 °. ) So that it can be tilted.

  In this configuration, the flow velocity of the fluid flowing in the divided flow path S is detected as the propagation time of ultrasonic waves transmitted and received alternately between the ultrasonic transmission / reception units 24A and 24B, and based on the difference in propagation time The flow rate of the fluid flowing in the tube 1 can be obtained, that is, measured, by multiplying the flow velocity by the cross-sectional area of the flow path.

  As described above, when the flow rate of the fluid flowing through the divided flow path S is measured to obtain the flow rate, the turbulence promoting member 6 flattens the flow velocity distribution of the fluid flowing into the divided flow path S. Therefore, compared to a configuration in which the tubular body is simply divided by the partition plate, the flow rate flowing through each divided flow path S is made uniform, and thus the flow rate of the fluid can be measured more accurately.

[Embodiment 2]
The flow rate measuring apparatus according to the second embodiment of the present invention uses the flow rate uniformizing structure of the flow path according to the above-described first embodiment , and examples of the fluid to be measured include gas and water. .

That is, as shown in FIG. 6, the flow rate measuring device 31 includes the flow equalization structure described in the first embodiment , that is, each divided flow path S <b> 1 provided with the turbulent flow promoting members 17 and 18 on the upstream side. , S2 and a pair of ultrasonic transmission / reception units attached to the left and right side plates 2 forming the outer wall portion of the tubular body part 32 through cylindrical attachment members 33, respectively. The ultrasonic wave propagation time (also referred to as transmission time or arrival time) is detected between the transmission unit 34 (34A, 34B) and the ultrasonic transmission / reception units 34A, 34B. The flow rate calculation unit 35 calculates the flow rate of the fluid based on the flow rate after obtaining the flow rate based on the time difference. In addition, this ultrasonic transmission / reception part 34 is attached in the position where an ultrasonic wave crosses the intermediate part of small division flow path S2.

  Further, in the flow rate calculation unit 35, the flow rate in the small divided flow path (also referred to as an ultrasonic measurement region) S2 and the flow rate in the tube body (flow path) 11 according to various flows of the fluid to be measured in advance. The relationship with the average flow velocity is stored as a correction coefficient, and the average flow velocity in the tube body 11 is obtained from the measured flow velocity using the correction coefficient.

  Note that the attachment direction of the ultrasonic transmission / reception units 34A and 34B is a predetermined angle θ in the horizontal plane with respect to the flow direction R (however, 0 ° <θ <90 °, but is preferably close to 0 °. ) So that it can be tilted.

  In this configuration, the flow velocity of the fluid flowing in the small divided flow path S2 is detected as the propagation time of the ultrasonic wave transmitted and received alternately between the ultrasonic transmission / reception units 34A and 34B, and based on this propagation time, the flow rate of the fluid is detected. An average flow velocity is obtained, and by multiplying the flow velocity by the cross-sectional area of the flow path, the flow rate of the fluid flowing in the tube body 11 can be obtained, that is, measured.

  As described above, when the flow rate is obtained by measuring the velocity of the fluid flowing from the large divided flow path S1 into the small divided flow path S2, the large divided flow path S1 and the small divided flow path S1 and the small divided flow paths 17 and 18 are obtained. Since the flow velocity distribution of the fluid flowing into the divided flow path S2 is further flattened, the flow rate of the fluid can be more accurately and accurately compared with a configuration in which the flow is divided only by one stage by the partition plate. It can be measured. That is, the flow rate flowing through each of the small divided flow paths S2 is constant, and the correction coefficient can be set constant regardless of the flow rate, thus facilitating calculation of the flow rate.

By the way, in the said Embodiment 2 , although it divided | segmented so that each of the large division | segmentation flow path S1 and the small division | segmentation flow path S2 might become two each, of course, it is not limited to two each, For example, one side is divided. You may divide | segment into 3 or 4 or more, and may divide both into 3 or 4 or more.

As for the flow rate uniform structures Oite described flow rate measuring apparatus according to the flow measurement apparatus and the second embodiment according to the basic configuration, the flow rate in accordance with the first flow rate equalizing structure and implementation according to the basic configuration The contents additionally described can be applied at the location of the uniform structure .

  To explain again, a turbulent flow promoting member with a sandpaper affixed to the wall surface is used. However, the wall surface 1a, 11a, 15a has a roughness equivalent to the same roughness scale and is a means such as sandblasting. It may be roughened with. In this case, this rough wall surface portion becomes a turbulent flow promoting portion.

  In addition, a wire mesh capable of exhibiting a roughness function corresponding to the same roughness scale is attached to the inner wall surface, or a wire having a diameter corresponding to the same roughness scale has an axial direction orthogonal to the flow direction R1. As shown, it may be arranged on the wall surfaces 1a, 11a, 15a.

Further, a fine cylinder having a height corresponding to the same roughness scale may be erected vertically on the wall surfaces 1a, 11a, and 15a such that the axial direction is perpendicular to the flow direction R1. .
Further, fine uneven portions having a height corresponding to the same roughness scale may be formed on the wall surfaces 1a, 11a, and 15a with striped members extending in the flow direction R.

  5 and 6, the turbulent flow promoting members 7, 17, and 18 are illustrated as having a finite length along the flow direction R, but may be provided on the entire surface of the wall surfaces 1a, 11a, and 15a.

It is sectional drawing of the tubular body which shows the fundamental structure of the flow volume equalization structure which concerns on this invention. It is a principal part notch perspective view of the tubular body in the same basic composition . It is sectional drawing of the tubular body which shows the flow volume equalization structure which concerns on Embodiment 1 of this invention. It is a principal part notch perspective view of the tubular body concerning Embodiment 1. FIG. It is a principal part notch perspective view which shows the basic composition of the ultrasonic type flow measuring device concerning the present invention. It is a principal part notch perspective view which shows the structure of the ultrasonic flow measuring device which concerns on Embodiment 2 of this invention. It is a principal part notch perspective view which shows the structure of the ultrasonic type flow measuring device which concerns on a prior art example. It is sectional drawing of the tubular body which concerns on a prior art example.

DESCRIPTION OF SYMBOLS 1 Tube 5 Partition plate 6 Turbulence promotion member 11 Tube 15 1st partition plate 16 2nd partition plate 17 1st turbulence promotion member 18 2nd turbulence promotion member 21 Ultrasonic flow measuring device 22 Tube part 24 Ultrasonic transmission / reception unit 25 Flow rate calculation unit 31 Ultrasonic flow measurement device 32 Tubular unit 34 Ultrasonic transmission / reception unit 35 Flow rate calculation unit

Claims (2)

The first partition plate is disposed so that the cross section of the flow path is parallel to the flow in the rectangular flow path and the flow path cross-sectional area is equally divided .
The second partition plate is disposed in the divided flow path divided by the first partition plate in parallel with the flow and so as to divide the divided pipe cross-sectional area equally, and the upstream end of the second partition plate Is positioned downstream of the upstream end of the first partition plate,
A flow equalization structure in a flow path, wherein a turbulent flow promoting portion is provided on a flow path wall surface upstream of the first partition plate and a divided flow path wall surface upstream of the second partition plate. In the middle of the flow path having the flow uniform structure according to claim 1, an ultrasonic transmission / reception unit is arranged in a direction crossing the flow path,
An ultrasonic flow measuring device comprising a flow rate calculation unit for calculating a flow rate of a fluid flowing through a flow path based on an ultrasonic propagation time in the ultrasonic transmission / reception unit.

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