JPH06331412A - Flow straightening device - Google Patents

Abstract

(57) [Abstract] [Purpose] To effectively rectify the turbulent flow due to the change in the velocity distribution of the fluid from the three-dimensional flow to the two-dimensional flow, and improve the measurement accuracy in the flow rate measurement unit. [Structure] Between a fluid supply flow path 1 having a circular flow path cross section and a three-dimensional fluid velocity distribution, and an inflow space 3 having a flat flow path cross section and a two-dimensional fluid velocity distribution, The fluid supply adapter 5 having a shape in which the cross section of the flow path changes asymptotically from the circular shape at the upstream end to the rectangular shape at the downstream end is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rectifying device for rectifying a fluid flowing from a circular flow passage to a flat rectangular flow passage.

[0002]

2. Description of the Related Art A gas meter is provided with a shut-off valve that shuts off a flow path to stop the supply of gas when an abnormality occurs, and a fluidic element is constructed with a gas stagnant space through a gas stagnant space downstream of the shut-off valve. Some of them are provided with a flow rate measuring unit (see Japanese Patent Laid-Open Nos. 4-278421 and 4-134218). The shutoff valve has a valve body that opens and closes the nozzle portion at the tip, and the flow path of the nozzle portion has a circular cross-sectional shape and the gas velocity distribution is three-dimensional. On the other hand, the flow rate measuring unit uses what is called a fluid vibration type flow meter which measures the degree of switching of pressure generated by the phenomenon of jet flow as the frequency and obtains the flow rate. Here, it is an absolute requirement that a flat flow passage that allows the gas velocity distribution to be two-dimensional is required. Therefore, the gas retention space immediately before the flow rate measurement unit is also a flat flow passage.

Therefore, the gas flowing from the nozzle portion of the shutoff valve into the gas retention space has a turbulent flow because the velocity distribution suddenly changes from three-dimensional to two-dimensional, and a vortex is generated at the connecting portion. When the turbulent gas is supplied to the flow rate measurement unit, the flow rate measurement accuracy deteriorates.

As a countermeasure against this, the above-mentioned JP-A-4-2784.
In the publication No. 21, the inlet flow path to the flow rate measuring unit is projected into the gas retention space, and a semi-cylindrical member serving as a rectifier is installed so as to cover this projection, and the gas flowing into the gas retention space is introduced into It is guided along the inner wall to the flow rate measurement unit.

On the other hand, in Japanese Unexamined Patent Publication (Kokai) No. 4-134218, the opening (nozzle) to the gas retention space on the flow rate measuring section side of the shutoff valve is covered with a wire net to rectify the gas. The wire net has a bottomed cylindrical shape having a circular bottom portion and a cylindrical side surface portion, and projects into the gas retention space.

[0006]

However, in such a conventional rectifying device, since the rectifying member is arranged in the gas retention space inside the fluidic element and the rectification is performed inside the fluidic element, the space of the fluidic element is reduced. There is a problem that the capacity is limited due to the relation, it is not possible to cope with a rapid change in the velocity distribution from three-dimensional to two-dimensional, and a sufficient rectifying effect cannot be obtained. Also, for those with a wire mesh,
When the flow of dirty gas becomes longer, the mesh gets blocked,
There is also a problem that the capacity is deteriorated.

Therefore, an object of the present invention is to effectively rectify the turbulent flow due to the change in the velocity distribution from three-dimensional to two-dimensional and improve the measurement accuracy in the flow rate measuring section.

[0008]

In order to achieve the above-mentioned object, the present invention measures a fluid supply channel having a substantially circular channel cross-section and a flow rate of the fluid supplied from this fluid supply channel. A flow path cross section is a circular portion whose one end is connected to the fluid supply flow path, between the fluid supply flow path and an inflow space which is in communication with the fluid supply flow path and has a rectangular flow path cross-sectional shape. An end is a rectangular portion connected to the inflow space, and a fluid supply adapter having a shape gradually changing from the circular portion to the rectangular portion is provided.

Further, a fluid supply channel having a substantially circular cross section and a flow rate measuring section for measuring the flow rate of the fluid supplied from the fluid supply channel are provided so as to communicate with the fluid supply channel. A semi-cylindrical member having an arc surface on the upstream side is arranged at an outlet on the side of the inflow space in the flow channel having a rectangular flow path cross section between the inflow space having a rectangular road cross section. A fluid supply adapter having a flat rectangular opening may be provided between both side edges and the opening edge of the outlet.

[0010]

According to the flow straightening device having such a structure, a three-dimensional velocity distribution is generated in the fluid flow in the fluid supply passage having a circular flow passage cross-sectional shape. By gradually changing from three-dimensional to two-dimensional in the adapter, the fluid can be supplied to the inflow space of the flow rate measuring unit having a rectangular flow path cross section with the velocity distribution rectified in two dimensions.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a rectifying device showing a first embodiment of the present invention, and FIG. 2 is a side view of the same. Fluid supply channel 1 with circular channel cross-section and three-dimensional fluid velocity distribution
And the inflow space 3 in which the velocity distribution of the rectangular fluid having a flat flow path cross section is two-dimensional, the fluid supply adapter 5 is provided. The fluid supply channel 1 corresponds to, for example, the nozzle portion on the gas outlet side of the shutoff valve in the gas meter, and the inlet space 3
Corresponds to the gas retention space immediately in front of the flow rate measuring unit which is provided on the downstream side of the shutoff valve and which is a fluid vibration type flow meter for measuring the flow rate of the fluid.

In the fluid supply adapter 5, the upstream end 5a on the side of the fluid supply channel 1 has a circular channel cross-sectional shape like the fluid supply channel 1, and the downstream end 5b on the side of the inflow space 3 is formed. It has a flat rectangular shape similar to that of the inflow space 3, and has a shape that asymptotically changes from the circular upstream end 5a to the rectangular downstream end 5b, so that there is no discontinuous portion in the structure of the flow path. ing. The fluid supply adapter 5 is manufactured as a metal or resin molded product.

According to the rectifying device having such a configuration, the fluid having a three-dimensional velocity distribution flowing through the fluid supply channel 1 is tertiary in the fluid supply adapter 5 due to the channel shape which gradually changes from circular to rectangular. The original flow asymptotically smoothly changes to a two-dimensional flow, and irregular turbulence or generation of vortices does not occur in the inflow space 3 and flows out in a rectified state. As a result, the measurement accuracy of the flow rate measurement unit is significantly improved.

3 and 4 show a second embodiment of the present invention. FIG. 3 is a perspective view showing another example of the fluid supply adapter. This fluid supply adapter 7 is formed by cutting both side portions (upper and lower portions in FIG. 4) of a cylinder obliquely from one end to the other end in a cylinder 9 having both ends open, as shown in FIG. A pair of flow path forming members 11a and 11b are installed. Thereby, the cylinder 9 and the flow path forming member 11
In the flow path surrounded by a and 11b, the upstream end 7a on the fluid supply flow path 1 side is circular, and the downstream end 7b on the inflow space 3 side.
Becomes a flat rectangular shape, and the upstream end 7a to the downstream end 7
The shape is such that the velocity distribution of the fluid changes asymptotically from three-dimensional to two-dimensional over b, and there is no discontinuous portion in the structure of the flow path.

Therefore, also in this embodiment, by providing the fluid supply adapter 7 between the fluid supply passage 1 and the inflow space 3, the same effect as that of the embodiment of FIG. 1 can be obtained.

FIG. 5 shows a third embodiment of the present invention. In this embodiment, the fluid supply adapter 7 shown in FIG. 3 is provided between the fluid supply channel 1 and the inflow space 3 to form a contracted channel, and the fluid supply adapter 7 and the channel space 3 are also provided.
Fluid supply auxiliary adapter 1 that forms an enlarged flow path between
3 is provided. Further, in the fluid supply flow channel 1, for example, a rectifier 21 in which the flow channel is divided into a plurality is stored.

The fluid supply auxiliary adapter 13 accommodates triangular flow path forming members 17 and 19 inside a housing 15, and the upstream end 13a of the flow path formed by the flow path forming members 17 and 19. Has the same rectangular shape so as to be aligned with the downstream end 7b of the fluid supply adapter 7, and this rectangular flow path gradually expands and communicates with the inflow space 3 through the rectangular flow path of the downstream end 13b. . Fluid supply auxiliary adapter 13
The mounting flange 15 integrated with the housing 15 is provided on the downstream side of the
a is provided, and the fluid supply auxiliary adapter 13 is attached to the fluidic element having the inflow space 3 via the attachment flange 15a. Further, the cylinder 9 of the fluid supply adapter 7 and the housing 15 of the fluid supply auxiliary adapter 13 are
Although it is shown as a separate member in FIG. 5, it is actually integrally molded.

With such a configuration, after the fluid velocity distribution is smoothly converted from the three-dimensional flow to the two-dimensional flow in the fluid supply adapter 7, the fluid supply auxiliary adapter 13 gradually changes the two-dimensional flow as it is. The flow is expanded and smoothly flows into the inflow space 3. As a result, the rectification effect is further enhanced, and the measurement accuracy of the flow rate measurement unit that constitutes the fluidic element is significantly improved. Also,
The rectifier 21 is effective in eliminating turbulence and vortices in the flow due to the shape of the upstream pipe and the like.

FIG. 6 shows the relationship between the flow rate Q and the vibration frequency f caused by the switching degree of the pressure in the flow rate measuring unit, that is, the fluid vibration type flow meter in the above embodiment. FIG. 7 is a conventional one in which a rectifier, a contraction channel and an expansion channel are not provided. According to this, the flow rate Q is 0.3-
In the range of 1.5 m ³ / h, in FIG. 7, a relatively large deviation from the straight line occurs, whereas in FIG. 6, it is recognized that remarkable linearity is obtained. That is, the flow rate Q and frequency f required for the fluidic gas meter
It means that the range of the proportional relationship with and is expanded, and the flow rate measurement range is expanded. Furthermore, the straight line portion tends to move slightly in the direction of the low flow rate region, which enables measurement of a lower flow rate.

FIG. 8 shows a fourth embodiment of the present invention. In this embodiment, a cylindrical member 23 is arranged on the side of the fluid supply channel 1 and a fluid supply adapter 25 is arranged on the side of the inflow space 3 between the fluid supply channel 1 and the inflow space 3, respectively. A semi-cylindrical member 27 having an arc surface on the upstream side is provided at the downstream end 25b.

The cylindrical member 23 has a taper 23a for contracting flow formed at the upstream end at an angle of 45 degrees, and the downstream cross-sectional shape of the flow path is circular on the downstream side of the taper 23a for contracting flow. 23 b is connected to the fluid supply adapter 25. A plurality of protrusions 23c are formed on the outer periphery of the cylindrical member 23 on the side where the contracting taper 23a is formed, so that connection to a hose or the like becomes easy.

The fluid supply adapter 25, like the fluid supply auxiliary adapter 13 shown in FIG. A rectangular channel is formed that expands toward the side. The height h of this rectangular channel is
By matching the inner diameter d _p of the flow path in the cylindrical member 23, a step is formed inside the connecting portion at the upper and lower portions of the downstream end 23 b of the cylindrical member 23 and the upstream end 25 a of the fluid supply adapter 25. The structure does not occur. Fluid supply adapter 25
A mounting flange 29 integrated with the housing 29 on the downstream side of the
a is provided, and the fluid supply adapter 25 has a mounting flange 2
The attachment hole formed in 9a is attached to the fluidic element having the inflow space 3 by 29b.

The semi-cylindrical member 27 is formed at the same height h as the flow path in the fluid supply adapter 25, as shown in FIG.
By installing the semi-cylindrical member 27 at the downstream end 25b in the fluid supply adapter 25, both side edge parts of the semi-cylindrical member 27 and the opening edge part of the flow path in the fluid supply adapter 25 on the inflow space 3 side are formed. A rectangular flow path will be formed between them.

According to this structure, the fluid of the three-dimensional flow flowing in the cylindrical member 23 is guided to the surface (arc surface) of the semi-cylindrical member 27 in the fluid supply adapter 25 and divided into two. In the process of reaching the flat and rectangular outlets on both sides of the semi-cylindrical member 27, the semi-cylindrical member 27 smoothly transitions to a two-dimensional flow and flows out into the inflow space 3 as a two-dimensional flow. Further, by making the height h of the flow passage in the fluid supply adapter 25 equal to the inner diameter d _p of the flow passage in the cylindrical member 23, there is no step at the connecting portion at the upper and lower portions of these both, so that This prevents the generation of vortices. Furthermore, by forming the contracting taper 23a on the upstream side of the cylindrical member 23, there is no step at the inlet of the cylindrical member 23, and this also prevents the generation of vortices.

FIG. 10 shows the relationship between the flow rate Q and the vibration frequency f in the fluid vibration type flow meter in the fourth embodiment shown in FIG. According to this, the linearity of the proportional relationship between the flow rate Q and the frequency f required for the fluidic gas meter is 0.25 to 0.25 as compared with FIG. 6 in the third embodiment of FIG.
It can be seen that it is further improved in the range of 0.8 m ³ / h.

[0027]

As described above, according to the present invention, since the velocity distribution of the fluid flowing in the fluid supply adapter is smoothly converted from three-dimensional to two-dimensional, the turbulent flow is effectively rectified. As a result, the measurement accuracy of the flow rate measurement unit can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view of a rectifying device showing a first embodiment of the present invention.

FIG. 2 is a side view of the rectifying device of FIG.

FIG. 3 is a perspective view of a fluid supply adapter showing a second embodiment of the present invention.

4 is a cross-sectional view of a flow path forming member used in the fluid supply adapter of FIG.

FIG. 5 is an exploded perspective view of a rectifying device showing a third embodiment of the present invention.

6 is an explanatory diagram showing a relationship between a flow rate and a vibration frequency in the fluid vibration type flow meter by the rectifier of FIG.

FIG. 7 is an explanatory diagram showing a relationship between a flow rate and a vibration frequency in a fluid vibration type flow meter using a conventional rectifying device.

FIG. 8 is a perspective view of a rectifying device showing a fourth embodiment of the present invention.

9 is a perspective view of a semi-cylindrical member used in the straightening device of FIG.

10 is an explanatory diagram showing a relationship between a flow rate and a vibration frequency in the fluid vibration type flow meter by the rectifier of FIG.

[Explanation of symbols]

 1 Fluid Supply Channel 3 Inflow Space 5, 7, 25 Fluid Supply Adapter 27 Semi-Cylindrical Member

Claims (2)

[Claims] 1. A fluid supply channel having a substantially circular channel cross-sectional shape, and a flow rate measuring section for measuring a flow rate of a fluid supplied from the fluid supply channel, the fluid supply channel communicating with the fluid supply channel. The flow path cross section is between the inflow space with a rectangular road cross section and
One end is a circular part connected to the fluid supply channel, the other end is a rectangular part connected to the inflow space, and a fluid supply adapter having a shape gradually changing from the circular part to the rectangular part is provided. Characterizing rectifier. 2. A fluid supply channel having a substantially circular channel cross-sectional shape, and a flow rate measuring section for measuring a flow rate of a fluid supplied from the fluid supply channel, the flow channel communicating with the fluid supply channel. A semi-cylindrical member having an arc surface on the upstream side is arranged at an outlet on the side of the inflow space in the flow channel having a rectangular flow path cross section between the inflow space having a rectangular road cross section. A rectifying device comprising: a fluid supply adapter having a flat rectangular opening formed between both side edges and an opening edge of the outflow port.