JPS5811813A - Flow meter - Google Patents

Abstract

PURPOSE:To prevent the influence of disturbance upon a flow of fluid in a flow passage, and to improve measurement precision, by arranging a splitter vane on the fluid exit side of the 2nd pipe with a slight interval to the flow passage wall of the pipe. CONSTITUTION:A splitter vane 18 has its upstream-side edge more at the downstream side in the flow passage of the 2nd pipe 7 than the opening 14 of a flow passage 16, and also has its one flank 20 at slight distance from the flow passage wall of the pipe 7. Further, its downstream-side edge is provided a little bit more on the upstream side than the opening 15 of the passage 16 in the flow passage wall of the 1st pipe in such a way that one flank 20 faces the opening 15. Then, even if disturbance is generated on the upstream or downstream side of the flow passage, a flow of fluid specially near the fluid exit 9 of the pipe 7 is stabilized without the influence of the disturbance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a flowmeter that measures the flow rate by fully utilizing vibrations of a fluid flowing through an internal flow path of a flowmeter.

The needle uses the property that the fii dynamic phenomenon of the fluid generated in the flow path is almost proportional to the flow velocity of the fluid, measures the frequency of the vibration, determines the flow velocity, and indirectly calculates the flow lt. These are conventionally known as Karman vortex fully stabilized, full buoyancy flowmeters, and vortex precession type flowmeters.

Compared to other types of flowmeters, such as iris flowmeters and hot wire flowmeters, flow meters that use vU have the advantage of having fewer measurement errors. In order to detect the entire pressure at the bottom, the relationship between the output of the pressure sensor and the flow rate is quadratic, and the detection error in the low flow area is large.The hot wire flowmeter uses a hot wire. Since the flow 4 is directly measured, emphasis is placed on temporal response.If the sensor is thin and small, its durability is poor, and the calculation display process is complicated, as it requires all electrical calculations such as a linearizer. become.

When using a flow meter that uses fluid vibrations for this device, it is good to measure the entire cycle of temporal fluctuations, whether the sensor is detecting the entire pressure or the flow velocity. Since output accuracy is not required, and the period of the measured temporal fluctuation is linearly proportional to the flow velocity or flow rate, calculation of flow 1 is extremely simple, and the device can be constructed at low cost. By the way, the Karman vortex flowmeter is a method that measures the generation period of the Karman vortex that is generated behind a blunt wj4 body in the flow path. For this purpose, the shape of the blunt V4 body, the structure of the entire flow path and the fluid must be designed or selected), depending on the case. Even if it is very clear in theory, such as optimizing the relationship with the wall, it is actually difficult to configure the structure to generate a Karman vortex in a completely stable manner. A full-width flowmeter has a feedback loose opening in the side wall of the main fluid flow path in an R-shaped pattern, and uses a controlled flow to jet the main fluid into the main fluid flow path through the feedback loop. The fluid vibration is stable because the flow is dynamically layered in the side chamber and the vibration frequency Mk is detected, but a feedback loop is required to stably oscillate the layered flow to the left and right side walls. The control flow ejected through has sufficient influence on the mainstream t
Since the diameter of the main flow path is relatively small, it is suitable for a flow rate needle for a small flow rate, but is not suitable for a large flow rate.

In addition, since it is necessary for a vortex precess flowmeter to generate all the swirling flow in the Venturi circle, a guide for generating swirling flow is provided at the inlet, and this guide acts as a resistance to the fluid flow n. , it becomes structurally complex.

The present invention is a flow rate needle that utilizes the fluid vibration, which has a simple structure, generates stable fluid vibration, is suitable for both large and small flow rates, has little pressure loss, and stably maintains fluid vibration. The overall purpose is to provide a flow meter that will

A further object of the present invention is to provide a compact flow meter that detects and displays the period of fluid vibration.

1 and 2 are cross-sectional views schematically showing the principle of the flow tItI' of the present invention. In the figure, reference numeral 1 denotes a first pipe forming a fluid outlet 2 and a fluid outlet 6, and a flow path from the fluid outlet 2 to the fluid outlet 3 of the line tube 1 has a first cylindrical surface 4, a truncated A conical surface 5 and a second cylindrical surface 6 having a smaller diameter than the first cylindrical surface 4 are successively connected concentrically. Reference numeral 7 denotes a second pipe that forms a fluid population 8 and a fluid outlet 9, and the wall of the flow path from the fluid population 8 to the fluid outlet 9 of the line tube 7 is in a plane that includes the central axis of the line tube 7. The flow passage surrounded by the arcuate wall 10 has a cross-sectional shape taken in a plane perpendicular to its central axis, which connects the fluid population 8 and the fluid outlet 9. It is located approximately at the center of the connecting central axis. The second tube 7 has an L-shaped support pipe 116 formed in the gastric wall of the narrow cross-section part of the flow path, and one end of the second tube 7 is fitted into the diametrical hole 12 of the tube 7. The other end of the support pipe 11 is fitted into a hole 16 made in the first pipe 1, and the twentieth pipe 7 is positioned concentrically within the flow path of the first pipe 1. The hole 16 made in the tube 1 is formed on the truncated conical surface 5 of the tube 1.
and the inside of the support pipe 11 and the hole 16 between the opening 15 and the opening 14 are communicated with the opening 15 formed in the cylindrical surface B near the connection part between the opening 15 and the second cylindrical surface 6. A fluid passage 16 is entirely formed in the cavity, and the fluid passage 16 connects the smallest front side of the flow passage of the second tube 7 and the # of the first tube 1.
, the vicinity of the fluid outlet of the second pipe 7 of IJ@ and the metal connection 0
The fluid outlet 9 of the second pipe 7 is supported in the first pipe 1 by a pipe 11 so that the fluid outlet 9 is located near the opening 15. , the flow line in which the gold fluid flows smoothly in the flow path of the first tube 1 is as shown in FIG. The flow velocity at the smallest cross section of the channel is maximum, and as it reaches the fluid outlet 9, the flow channel cross-sectional area gradually expands and the flow velocity gradually decreases.

Therefore, the static pressure P of the fluid at the horizontal portion of the minimum cross section and the fluid outlet 9
Static pressure P of the fluid at . as well as the cylindrical wall 6 of the first tube 1
When the static pressure Po' of the fluid near the opening 15 and Kinkosai, Pt<P. , P in Po. ' Therefore, Pt<Po'1・
It can be seen that the relationship (1) is established.

Therefore, the pressure Pr at the smallest area part of the flow path of the tube 7.

and the pressure P near the opening 15. As shown in FIG. A flow occurs. This opening 1
The fluid flow ejected from the pipe 7 is deflected so that the entire fluid flowing through the pipe 7 adheres to the pipe wall on the diametrically opposite side with respect to the opening 14, so that an arcuate wall is formed downstream of the opening 14 as shown in the figure. When the flow line of the fluid flowing in the flow path of the pipe 1 is in the state shown in FIG. P for the adults supplied, P for the same two P. Ki P. ′
Hibiki・Fist (2) and Na), fluid passage 16
The pressure difference that completely drives the fluid in the direction of arrow A disappears, the flow 'nv'i in the flowing relief 16 in the direction of arrow entry disappears, and the flow ftB in the separation process also disappears. All light n
The flow line of the fluid returns to the shape shown in the first diagram.Then, the pressure difference shown in equation (1) above will occur again. The state shown in Figure 2 is repeated alternately, and changes in the body pressure and/or fluid static pressure are periodically repeated in the minimum area part of the flow path of v7, near the fluid outlet 9, and in the fluid passage 16.ゐWhen such periodic fluctuations in the flow state, that is, fluid vibrations, are generated by the first pipe 1, the second pipe 7, and the fluid passage 16, this fluctuation in flow velocity or pressure The fact that there is a linearly proportional relationship between the frequency f and the flow tG of the fluid flowing through the channel #7 means that the total frequency of the fluid vibration U
It is self-evident from the theory that W of the flowmeter used is self-evident, and the present invention detects the frequency f of this fluid vibration and uses a flowmeter to determine the mud tank G<T. In this case, when the fluid is flowing in a stable state, which is the illusion of flow rate measurement, the fluctuation in the flow velocity or pressure is as shown in Figure 6 (showing the temporal change in the output of the hot wire sensor corresponding to the flow velocity). However, when a disturbance occurs upstream or downstream of the flow path of a flowmeter, the turbulence of the fluid caused by the disturbance is shown in Figure 2. The generation position of the flow fiB accompanied by separation is made completely unstable, and therefore, as shown in Fig. 41 (which shows the temporal change in the output of the hot wire sensor in the same way as in Fig. 3), the temporal change in the periodic change in the fluid vibration is Fluctuations may become large, resulting in a miscount of the frequency f and a detection error.

The purpose of this invention is to stabilize the occurrence of the fluid vibration, thereby making the detection of the frequency f of the fluid vibration completely accurate and eliminating the detection error of the flow rate G as much as possible. In a flowmeter that is equipped with a full passageway for cooling the first pipe j'y and the second pipe, a cross section of 2 points in a plane roughly including the central axis on the outlet side of the second pipe - 10 = thin wall of the face plate. Streamlined splitter vanes? 11 - The upstream end of the splitter vane is spaced a certain distance from the inner wall of the second tube so that the upstream edge of the splitter vane is connected to the flow of the fluid flow in the second tube. The entire downstream end of the violet is located upstream of the opening in the flow path wall of the first pipe, and the approximately central portion in the width direction thereof is arranged to face the fluid path. Further, the fluid flow n near the fluid outlet of the second pipe is stabilized.

No. 51 shows an example of one aspect of the present invention. In the figure, the first tube 1 is formed into a double structure of an inner tube 101 and an outer tube 102.
, the inner tube 101 has a cylindrical surface 4, a frusto-conical surface 5, and a cylindrical surface 6 whose inner diameter is smaller than the inner diameter of the cylindrical surface 4, all extending from the fluid outlet 2 to the fluid outlet 3 in the central axis direction. An annular body 21 whose inner diameter is equal to the inner diameter of the cylindrical surface 4, which is manufactured by die-casting an aluminum alloy and is fitted into the inner cavity of the aluminum alloy outer tube 102. A strained flow element 2 made of aluminum alloy wire is fully supported at the checkpoint of the lattice 22.
With all three still in contact, caps 103 and 104 are screwed onto both ends of the outer tube 102, thereby integrating the inner and outer tubes 101 and 102. cap 105
, 104 should, of course, be provided with openings so as not to create any resistance to the fluid flowing into or out of the inner pipe 101.

A notch 106 is formed in a part of the truncated conical surface 5 of the inner tube 101 in a plane perpendicular to the central axis and is parallel to the central axis of which the bottom wall 105 extends. At a position closer to the fluid outlet 3 in the direction of the central axis, a rectangular hole 10 is formed by cutting out the entire tube wall of the wire tube 101 in the diametrical direction of the inner tube 101.
7, and the hole 1 is formed in the bottom wall 105 of the notch 106.
3. A hole 107 is bored parallel to the central axis of the full circular tube 101, and a truncated conical surface 5 and /″f of the inner tube 101 are formed in the hole 107 on the − plane. , or the flow path surface 108 is formed on the same plane as the cylindrical surface 6, and the outer circumferential surface 109 of the inner tube 101 is formed on the opposite side of Ii, and the flow path surface 10
8, an opening 15 is formed in the hole 16, and a passage 110'f is made to fully communicate with the opening 14 and the hole 16. The entire length of the piece 111 made of die-cast electrically insulating synthetic resin is fitted into the passage 110'f.

The second pipe 7 is formed of an aluminum base metal in the same shape as in FIG. , its opening 14 is M, and one end thereof is connected to the hole 12 of the tube 7.
and the other end is inserted and fitted into the hole 13, and the second tube 7 is the first
It is supported on the tube 1 in the same way as the case. Between both openings 14 and 15, the inner cavity of the support pipe 11, the hole 13, and the passage w! A fluid passageway 16 is formed by r110.

The splitter bay 718 is formed in an annular or arcuate shape concentrically with the second pipe 7, and its upstream end is entirely opened into the channel wall of the pipe 7 near the fluid outlet of the second pipe 7. -13- integrally formed with the tube 7, or made of aluminum alloy so as to be located downstream of the opening 14 and approximately parallel to the inner wall of the tube 7 with a slight distance between the leg pieces 19; The leg piece 19 is formed as a separate body and is attached to the pipe 7 f'L.

iM on the -F flow side of the splitter bay 718 is the first pipe 1
One side 20 of the vane 18 is placed in front of the opening 15 at an appropriate distance from the opening 15 of the fluid passage 16, which is opened in the flow path wall of the vane 16. : The leg piece 19 (is connected and fixed to the pipe 7 at a position that does not affect the occurrence of filtration 21 in the case of separation). The cross-section at is a streamlined shape such as a thin protruding shape or a convex lens shape.

The piece 111 is exposed to heat i! inside the passage 110!
Ili! 60 is suspended on an electric wire connected to this, and the electric wire is connected to a connection terminal 31.31 set upright on the outer peripheral surface 109 of the piece 111.

The thermal storage 30, power supply and connection terminal 51 are provided when the piece 111 is die-cast. A hole 112 is bored in the outer shrine 102 at a position facing the connection terminal 31.31, and inside the hole 112-14- a socket 52 for a detection electric circuit, which will be described later, is connected to the connection terminal 31.31. , at the same time outside W
It serves as a rotation stopper for inner tube 101 relative to 102 .

The detection electric circuit includes a distortion wave filter and a comparison pulse generator 3 which are connected to the input terminal of the self-socket 62, and a square pulse counter 34 that counts all the rectangular pulses that are outputted to the generator 33 by 5%. and a display 35 for directly displaying or calculating and displaying the Hals reference counter 34, and a suitable power source.

In the embodiment with the above configuration, the fluid to be measured is
3 through the fluid inlet 2 of the first tube 1 into the flow path of the tube 1, and when flowing out from the fluid outlet 5, the flow n shown in FIGS. 1 and 2 respectively. Occurs periodically. Due to this periodic fluid change, the hot wire 30 exposed and suspended within the fluid passage 16 connects the terminal 31 with a special output at the frequency of the change in generation and cancellation of the fluid flow n within the fluid passage 16. occurs in The comparison pulse generator 36 rectifies this output and converts it into a waveform 'fC,' and then converts it into a full square wave pulse.The pulse counter 34 counts the square waves and displays the frequency on the display 65. The splitter vane 18 exhibiting the calculated flow t is arranged such that its upper N side edge is located downstream of the opening 14 of the fluid passage 16 in the flow path of the second tube 7. and its side surface 20 is arranged substantially parallel to the flow of the pipe 7 at the full distance apart from the wall of the pipe 7, and its downstream end is parallel to the flow of the first pipe W! Since it is located slightly upstream of the opening 15 of the fluid passage 16 that opens in the r wall, and the side surface 20 is located opposite the opening 15, even if a disturbance occurs upstream or downstream of the flow path, , in the flow path, especially the second tube 7
The fluid flow 2t in the vicinity of the fluid outlet 9 is stabilized without any influence of the disturbance, and the generation position a'i of the flow jLB with separation is stabilized, and the fluid flow in the fluid passage 16 is generated and Since the resolution is made to be almost unaffected by the disturbance, the output of the heating wire 30 is assumed to have an approximately regular circumference J4J]t-'f as shown in FIG. Eliminate temporal fluctuations (Fig. 4 Diagnosis), and make it into the original storehouse of Miscount Temple.

According to the above example VC, for the fluid known by It was confirmed that when the frequency f (c) of Its corresponds to t, there is a substantially linear relationship as shown in FIG. Taking the measurement case as an example, when G is 12 gr/aec, f is 235 Hz, and when G is 20 Hr/sea, f is 400.
When Hv and G are 66 gr/sea, f is 710Hz
It is linearly proportional to f and current G, and it is extremely easy to calculate and display current from frequency f. ! I expressed breast milk.

J to the above example? Flow path surface 1 of the piece 111 at IA
08 near the opening 15 of the cylindrical surface, ' or the front ml
On the upstream side of the second 17 arcuate surfaces 10 near the opening 14, there are pressure sensors 41 and 42? , the receiving MA
Bury it so that the surface is almost flush with the channel wall surface.
It was also confirmed that, in the case of ci, it was possible to completely eliminate the current flow at the frequency f. Similar results can also be obtained by providing microphone sound sensors at the positions of the pressure sensors 41 and 42. Even in this case, the splitter vane 18 was able to remove the influence of disturbance to a large number of young trees.

Note that the group +115 shown by the two points @ gland in FIG.
If you install the device in 115, you can use it for hand-held use.

FIG. 7 shows a modification of the above embodiment, in which the first pipe 1t-5
Part 20 of die-cast molded aluminum pot
Divided into parts 1, 202, and 203, with a cutout 20 in part 201.
4, the hole 16 is bored in the surface 205 of the portion 202, and the ultrasonic transmitter 51 and receiver 52 of the ultrasonic oscillator 50 are connected downstream of the fluid outlet 2 of the second pipe 7. ift! arranged at diametrically opposed positions and arranged within the annular groove 209.
3 Plant the terminal 55.5 (S) on the hoe ring 210,
A terminal 55 is connected to the ultrasonic oscillator 50 and its production circuit 54, and a terminal 56 receives the signal #52 and a generator 57 that changes the output waveform of the receiver 52 into a warm sine wave. It consists of a rectangular pulse generator 58 that converts the rectangular pulse into a rectangular wave, a pulse counter 592 that measures the rectangular pulse, and a display 60 that converts the measured frequency f or flow ZW of the counter 59 and displays it. It is connected to the detection electric enclosure.

In this variant, the downstream 9 of the splitter vanes 18
The UI end gland is arranged so as to be on the upstream side of the line connecting the ultrasonic transmitter 51 and the receiver 52, and is W-shaped so as not to obstruct the reception of the ultrasonic signal. is the same as that in FIG. 5, and the same parts as in the fifth part are indicated by the same reference numerals. In addition, 56 in the figure is Goshi sio, 4 Keiwei, 207,2
08 shows the hole, 61162t shows the plug, and 206 shows the entire cap.

In the present invention, a fluid inlet and a fluid mouth opening are provided at both ends of the central axis, and the flow passage cross-sectional area in a plane perpendicular to the central axis is reduced at least on the fluid outlet side.
A first tube of ``x M'' is installed approximately concentrically in the flow path of the first tube, with a fluid inlet and a fluid outlet opening at both ends of the first tube in the same central axis direction, and the vltl A venturi-shaped second tube forming a flow path having a minimum section of #L channel cross-section between the human body and the fluid outlet, and a flow path wall near the minimum section of the flow path cross-sectional area of the second tube. an opening formed in the second Q.
The flow path of the first pipe, such as near the blind fluid outlet, has a fluid passage communicating with an opening formed at a suitable position, and the fluid is introduced from the fluid inlet of the M1 pipe to the fluid outlet. When the introduced pressure is at the minimum cross-sectional area of the flow path of the second pipe and its fluid channel a) due to a change in static pressure, the fluid flows into the fluid passage. A sensor is designed to detect and output periodic changes in the state of the fluid due to repeated occurrence of the phenomenon of stopping. It is installed on the flow wall of the pipe and detects all the frequencies of the changes.It does not directly detect all the physical quantities that indicate the fluid condition such as pressure and velocity of the fluid. Since the sensor detects the frequency of change, even if a sensor that conventionally uses a physical quantity that indicates the state of the fluid is used, the detection and the integration of its output are not important (the frequency of change in the physical quantity can be detected). As long as the responsiveness is at a certain level, a low-cost sensor can be used for a long time, and the structure that generates fluid vibrations is the first pipe, the second pipe, and the second pipe. An opening in the flow path wall at the minimum cross-sectional area of the flow path and an opening provided at an appropriate position on the flow path wall in the first hole, such as near the fluid outlet of the second pipe.
By communicating with the fluid passages, periodic changes in fluid flow can be stably generated and maintained, and periodic changes in fluid flow can be prevented regardless of the size of the flow source. The structure is simple and can be used in any flow area by appropriately selecting the flow path area ratio 'ItiM of the first and second pipes, and the fluid vibration is caused by the fluid flow generated in the fluid passage. Since the vrr of the second pipe and the static pressure at the exit port are completely changed by using the t, it is possible to understand the change in the fluid flow n state as a pressure change, and the 2g degree of flow in the fluid passage can be understood as a change in the fluid flow n state. Since it can be detected as a change, a wide range of sensors such as pressure sensors and speed sensors can be used.

-21- In particular, in the present invention, splitter vanes are arranged at a slight interval on the flow path wall of the chain pipe on the fluid outlet side of the second pipe, and a cross section in a plane including the central axis of the vane is provided. The end edge of the splitter bay 7 on the upstream side is formed to have a cross section exhibiting a completely thin streamlined shape. The vane is located in the flow path of at least the second pipe on the downstream side of the opening of the passage, and one side of the vane is connected to the opening of the fluid passage having one opening in the flow passage wall of the first pipe. The opening is located on the upstream side and faces the opening, thereby completely stabilizing the flow of the fluid near the fluid outlet of the second pipe, so that no disturbance occurs on the upstream or downstream side of the flow path. Even if this occurs, the splitter behen does not maintain the fluid flow n or flow n in the fluid passage due to the stabilizing effect of the fluid flow n produced in cooperation with the flow passage walls of the first pipe and the second pipe. The flow of the second pipe that causes the anti-6f phenomenon that stops INrThe generation of the fluid flow n accompanied by separation that periodically occurs and disappears downstream of the opening in the wall.The vertical position is stabilized, and the position of the separation streamline is t to disturbance 22
- Since it does not cause μ sea bream, there is no disturbance caused by disturbance on the output of the sessa, and therefore, the installation of the splitter tube vanes is accurate over a wide range of flow ranging from a small flow point to a large miscarriage. It is possible to obtain a good and stable output, improve distance measurement accuracy, and have the effect of expanding the area of bait storage area for measurement.

If the splitter vane is placed closer to the center axis with respect to the flow B shown in Fig. 2, regular changes in the flow n'$ and y may be blocked. It is preferable that the outermost separation streamline of the miscarriage of flow B with separation shown in FIG. ym* accompanying craftsman f
One side of the splitter vane facing the channel wall of the second tube is concentric with the second tube. Preferably, the splitter vanes are formed as shown in FIG. 7 ha, said Nakagami@
'l: It may be formed in an annular shape with a center, but it is preferable that the fluid passage is arranged in an arc shape with a mouth τ opening at the flow wall of the first and second tubes. in this case,
Preferably, it is formed at the back of the body.

In addition, the splitter vane is connected to VCC2 as shown in the example.
Instead of being integrally formed with the zero tube or adding it to the second tube, it may be attached to the first tube with a leg piece.

Even in the case of example n, the leg piece fixing the splitter vane to the 11th pipe and the 2nd pipe is, of course, provided in the case where it does not inhibit the formation of the splitter vane that accompanies the above-mentioned separation. According to the present invention, a sensor with a cheaper and simpler structure than the above can be used, and since the frequency of It body vibration has a primary relationship with the flow rate, it is possible to calculate the flow rate from the frequency. The electrical circuits used are simple, and it is also possible to provide a hand-held flow meter that houses these electrical circuits and a suitable power source in its handle.

[Brief explanation of the drawing]

Figures 1 and 2 are Hou Ni diagram and Figure 3 are
Figures 4 and 4 are boat diagrams showing an example of the sensor output, Figure 5 is a cross-sectional view of an example of the uninvented Kazuya, and Figure 6 shows the relationship between the component frequency and current. Diagram, Figure 7 is the 5th
FIG. 7 is a cross-sectional view of a modification of the figure. In the figure, 1 is the first pipe 2, its fluid inlet 3 is its fluid outlet, the second pipe 8 is its fluid inlet 9, its fluid outlet 11 is the support pipe 14, 15 is the opening 16, and the fluid passage 18 is The splitter vanes 30, 41, 42 and the sensor 50 are representative of all the trailing wave oscillation devices, respectively. =25- 111 Figure 5 Figure 113 Figure 4

Claims (1)

[Claims] (1) A fluid inlet and a fluid outlet are opened at both ends in the direction of the central axis, and the flow wrlf in two directions in a plane perpendicular to the central axis! The fr surface ram forms a small flow path at least on the fluid outlet side, and is arranged approximately concentrically with the flow path surface of the first pipe and the first pipe, and both ends in the direction of the central axis thereof. A fluid inlet and a fluid outlet are provided at each side, and the flow path has a minimum cross-sectional area approximately at the center in the direction of the central axis.
a venturi-like second tube formed with a venturi tube, a flow path wall near the minimum part of the flow surface compensation of the second tube, and an opening in the flow path wall of the first tube; a fluid passageway communicating with the opening of the fluid passageway; a sensor that detects and outputs periodic changes in the state of the fluid; C2 is arranged at a slight interval '(i-n) from the inner wall of the tube on the fluid outlet side of the tube, and the cross section in a plane including the central axis has a thin-walled slender shape, and the second a thin plate-like splitter vane having a width of i3T along the inner wall of the pipe, and the downstream edge of the splitter vane in the flow direction of the fluid flowing on the flow path is connected to the second pipe of the fluid passage. The downstream edge thereof is located upstream of the opening opened in the flow path wall of the first tube of the body passageway. , and its substantially central portion in the width direction is arranged to face the fluid passage to stabilize the flow n of the fluid flowing through the flow passage. (2) The splitter. 19. The flowmeter according to claim 1, wherein the vane is arranged coaxially with the second pipe and has a length of 7″L, and is formed integrally with the second pipe. ) The splitter bay 7 is disposed coaxially with the second tube, and is centered at a point a connecting the central axis and the center of the opening of the first tube in a plane perpendicular to the central axis. The flowmeter according to claim 1 or 2, wherein the flowmeter is formed in an arc shape having a central angle of about 30° to 180°.