JP2524595Y2 - Fluid vibration type flow meter - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The invention is applicable to various fluids (gas, liquid) including gas meters.
With respect to a fluid vibration type flowmeter for measuring the flow rate of a fluid, more specifically, a nozzle having a nozzle ejection surface orthogonal to the flow path is disposed in the flow path, and the ejection side of the nozzle is arranged with respect to the axis of the nozzle. A channel enlargement portion having a symmetrical enlarged channel inner wall surface is provided, and a target that inhibits a straight flow of a jet ejected from a nozzle is provided at a central portion of the channel in the channel enlargement portion, and further, a downstream side of the channel enlargement portion. And a narrowed flow passage portion having a narrower flow width than the rear end of the enlarged flow passage portion. The inner wall surface of the enlarged flow passage is smoothly formed in a main arc portion in contact with the nozzle ejection surface and a main arc portion. And a sub-arc portion connected smoothly to the enlarged wall portion and connected to the throttle channel portion on the downstream side, and the enlarged wall portion is located at the target position in the channel direction. A structure that enlarges the flow path toward the corresponding position on the downstream side The present invention relates to a fluid vibration type flowmeter.

[Conventional technology]

This type of fluid vibration type flow meter has been proposed as one that can achieve structural simplicity, accompanying simplicity in manufacturing, cost reduction, and the like. FIG. 1 shows a plan view of such a fluid vibration flow meter. The operating principle of this fluid vibration type flow meter will be briefly described. The jet jet from the nozzle jet surface (11) bypasses the side of the target (20) and flows out of the throttle channel (13). (F1), which diverges from the main stream (F1) of the jet and collides with the sub-arc portion (18) in the enlarged channel portion (12) or the reduced cross-sectional portion forming the throttle channel portion (13), and the flow And a return flow (F2) flowing backward in the road. Here, the return flow (F
2) smoothly returns to the nozzle ejection surface (11) along the enlarged wall (17) and the main arc (16), and the jet main flow (F1)
Will be affected. In the flow meter of this type, when the fluid is ejected from the nozzle, the jet flow is drawn to the side wall portion, which is the inner wall surface (15) of one of the enlarged flow channels along the flow direction, and flows by the Coanda effect. Become. That is, the jet does not travel straight and is distorted toward any of the side wall portions. At this time, the return flow (F
2), and this flow imparts fluid energy in a direction perpendicular to the direction of jet flow in the vicinity of the nozzle ejection surface, and in a subsequent step, the jet flows along the opposite side wall. That is, this return flow (F2)
Will play a role as a control flow for the main jet flow near the nozzle outlet, and a phenomenon occurs in which the jet ejected from the nozzle flows alternately on both sides of the target. Vibration is effectively induced.) Further, in a flow meter having a configuration in which only the target is arranged in the enlarged channel portion, the state of the vortex formed in the wake formed downstream of the target also affects this vibration phenomenon. This oscillation period is generally proportional to the fluid flow through the flow meter. Therefore, utilizing this phenomenon, the flow rate of the fluid flowing through this flow path is measured.

That is, a mechanism for detecting pressure or flow rate is provided at a pair of measurement positions (55, 55) sandwiching the jet flow near the downstream side of the nozzle ejection surface (11) in the fluid vibration flow meter shown in FIG. Detects the change in pressure or flow rate caused by the phenomenon that the jet flows alternately on both sides of the target,
The flow rate is detected by measuring the frequency.

[Problems to be solved by the invention]

The state of the inflow fluid (the state at the nozzle orifice) in such a fluid vibration type flowmeter is a major factor that greatly affects its performance. However, since such a fluid vibration type flow meter itself is new, it has not been known what the configuration of the flow path width of the nozzle is good.

Therefore, an object of the present invention is to dispose only a target in a flow path and to form a return flow satisfactorily by a shape of an inner wall forming the flow path. An object of the present invention is to provide a fluid vibration type flowmeter having a nozzle flow path width structure within an allowable value and having a small error over the entire measurement target region.

[Means for solving the problem]

In order to achieve this object, the characteristic configuration of the fluid vibration type flow meter according to the present invention is as follows. The flow path in the nozzle of the nozzle is formed between a pair of linear inner walls connecting between the nozzle inlet end face and the nozzle ejection face. The width of the flow path in the nozzle is changed toward the nozzle ejection surface, and the width of the ejection portion of the nozzle is wo, and the width of the suction portion of the nozzle is wi / wo is within 0.9 to 1.2 (except when Wi / wo = 1.0), and the operation and effect are as follows.

[Action]

That is, in the fluid vibration type flowmeter of the present application, the pair of inner walls forming the nozzle are configured as linear wall surfaces, and the separation width between the two inner wall surfaces changes in the flow direction. In other words, this nozzle is configured to expand or contract toward the nozzle ejection surface. And the width of the nozzle spout is wo,
When the width of the suction part of the nozzle is wi, wi / wo is 0.9 to 1.
It is within two.

Now, as a nozzle configuration to be adopted in such a fluid vibration type flow meter, a main element is an error called ΔE due to a change in the nozzle width (Emax in the flow rate-instrument difference characteristic curve (positive side). ) -Emin (maximum value on the minus side)) and the pressure loss in this fluid vibration type flowmeter. Here, when the aforementioned wi / wo is swung to the plus side with respect to 1, ΔE increases and the pressure loss decreases. One
When ΔE is shifted to the minus side, ΔE decreases to a certain value and then gradually approaches the lower limit, and the pressure loss monotonically increases (see FIG. 4). . When wi / wo is kept within the above-mentioned range, ΔE can be maintained at a practical level while the pressure loss is kept at a level allowed by the flow meter.

[Effect of the invention]

Therefore, when the configuration of the present application is adopted, only the target is disposed in the flow path, and the shape of the inner wall forming the flow path favorably forms the return flow. It was possible to obtain a fluid vibration type flow meter having a small error over the whole range and a pressure loss within an allowable range.

Another characteristic of this type of flow meter is that its structure is simpler than that of a fluid vibration type flow meter with a member that actively forms a return flow, which has conventionally been put to practical use. Thus, a high-precision fluid vibration type flowmeter can be obtained.

〔Example〕

A flow measuring device (1) incorporating the fluid vibration type flow meter of the present application will be described with reference to FIGS. First
FIG. 1 shows a plan view of the flow rate measuring device (1), and FIG. 2 shows details of a main part of a fluid vibration type flow meter (2) incorporated in the flow rate measuring device (1). . First, a schematic configuration of the flow measurement device (1) will be described. This device (1) is configured such that the inflow direction (A) of the fluid (f) to be measured is 180 degrees opposite to the outflow direction (B). That is, the fluid flowing from the device inlet (3) flows into the storage part (6) via the shutoff valve part (5). Then, after being subjected to rectification by the rectifier (7) disposed in the storage section (6), the rectifier flows into the nozzle (8). Jet surface of this nozzle (11)
The jet flow that flows out becomes an oscillating flow in the enlarged channel portion (12) of the fluid vibration type flow meter (2) and flows out from the throttle channel portion (13) provided downstream thereof.

Hereinafter, the configuration and operation of each operation unit will be described in more detail. First, the flow up to the nozzle (8) will be described. Fluid (f) such as gas or water flowing from the apparatus inlet (3) passes through the substantially L-shaped first curved path (4) and the shutoff valve section. Sent to (5). After passing through the shut-off valve section (5), it flows into the storage section (6). A rectifier (7) is provided in the storage section (6). The rectifier (7) has a semicircular shape, and is arranged to face the inlet (8i) of the nozzle of the above-mentioned fluid vibration type flowmeter (2). Here, the nozzle (8) is formed by a pair of protrusions (9), which protrude into the above-mentioned storage (6).

Then, from the positional relationship between the rectifier (7) and the pair of projecting portions (9), the pair of edge portions (10) of the rectifier (7) is located at a position opposite to the pair of inlet end portions (9t) of the projecting portion (9). Thus, it is located on the downstream side in the flow channel direction. Therefore, a pair of detours (L1) is formed between the pair of edge portions (10) and the pair of protrusion outer surfaces.

Further, in the pair of detours (L1), the fluids flow in opposition to each other and merge at the upper portion of the central flow path (L3) connected to the flow path (L2) in the nozzle formed in the nozzle. Is formed. Here, a pair of bypass flow paths (L1)
And a pair of vortex regions (v) formed between the pair of inlet-side ends (9t) described above. Further, this fluid flows from the nozzle (8) into the fluid vibration type flow meter (2). Here, the surface formed by the inlet end (9t) is referred to as the nozzle inlet end.

This fluid (f) flows through the flow channel expansion section (12) provided downstream of the nozzle ejection surface (11) of the fluid vibration type flowmeter (2) and the throttle flow path section (13) to flow into the device. It is configured to flow out of the exit (14).

Here, the positional relationship between the rectifier (7) and the protruding portion (9) will be described in terms of actual numerical values.
And b, and the maximum distance c between the inlet end (9t) and the rectifier (7) is as follows.

a / (a + b) = 0.36 to 0.54 (0.47 in Figs. 3 and 4) c / wo = 3.0 to 4.5 (3.7 in Figs. 3 and 4) where wo is the width of the nozzle ejection part .

Next, the configuration of the nozzle (8) will be described. The nozzle (8) has a width wi of the suction part and a width wo of the ejection part, and is formed by a pair of linear inner walls (8w) having a linear shape between their edges, and has a constant flow straightening length. (Nl). Then, in order to obtain this rectification length (Nl), a pair of protrusions (9) is formed to protrude from the storage part (6) as described above. The pair of protrusions (9) are formed of a rectangular member having a protrusion width (NW) and a protrusion length (which is substantially equal to the aforementioned rectification length) (Nl), and both side portions thereof Left and right side storage area (6L)
(6R) is formed, and the width of the left and right side storage areas (6L) and (6R) is formed to be substantially equal to or greater than the rectification length (Nl) described above. The suction-side end (9R) of the nozzle (8) in the protruding portion (9) has an arc shape, and the radius of the arc is the nozzle inlet arc diameter rn. The actual numerical values are as follows: wo = 3.2 mm rn / wo = 0.31 Nl / wo = 4.65 to 6.25 (6.25 in the case shown in Figs. 3 and 4) NW / wo = 2.66.

Subsequently, the configuration of the fluid vibration type flow meter (2) will be described below with reference to FIG. This fluid vibration type flow meter (2) is composed of the nozzle (8), the flow path enlarging section (12)
And a throttle channel portion (13) that smoothly connects to the channel expansion portion (12). Here, in the nozzle (8), the nozzle ejection surface (11) is in a state orthogonal to the flow path direction. Next, the enlarged flow path portion (12) will be described. The enlarged flow path section (12) has an enlarged flow path inner wall surface (15) symmetrical with respect to the axis of the nozzle coinciding with the flow direction. The inner wall surface (15) has a main arc portion (16) in contact with the nozzle ejection surface (11), a straight wall portion (17) connected thereto, and a sub arc portion (17) connected to the straight wall portion (17). 18). The rear end of the sub-arc portion (18) is connected to the above-described throttle channel portion (13) by an arc-shaped discharge arc portion (19). Further, a target (20) is provided at the center of the flow channel in the flow channel enlarged portion (12) to prevent the jet flowing from the jet surface from going straight. This target (20)
This has the effect of stably switching the flow direction of the jet in a minute flow rate region. Where the main arc (16)
Is the radius of R, the distance of the center of the sub-arc portion (18) in the flow direction from the ejection surface is L, the distance of the center of the sub-arc portion (18) in the cross-flow direction from the nozzle axis is x, The radius of the arc (18) is r, the width of the target (20) is Tw, and the target (20)
Assuming that Tl is the distance in the flow direction from the ejection surface at the tip end of the flow path and T is the width of the throttle flow path (13), wo, R, L, x,
r / Tw, Tl, and P are R / wo = 3.1 to 5.3 (4.38 in the case shown in FIGS. 3 and 4) L / R = 1.5 x / R = 0.7 to 0.8 (FIG. 3, FIG. In the case shown in the figure, 0.78) r / R = 0.45 to 0.56 (0.5 in the case of FIGS. 3 and 4) Tw / wo = 1.56 to 2.00 (The case in the case of FIGS. 3 and 4 1.75) Tl / R = 0.94 to 1.1 (1.07 in the case of FIGS. 3 and 4) P / R = 1.24 to 1.62 (1.36 in the case of FIGS. 3 and 4) .

Further, the radius r1 of the discharge arc portion (19) is substantially equal to r, and the maximum transverse dimension of the flow channel enlarged portion (12) is 2 (x + r).
/R=2.56, and the distance from the nozzle ejection surface (11) to the throttle channel (13) is (L + r + r1) /R=2.5. The distance Z from the nozzle ejection surface (11) to the rear end of the fluid vibration type flowmeter (2) is about Z = 2.86R. Here, the actual dimension of R is 14 mm.

The height H (width in the direction perpendicular to the plane of FIG. 2) of the fluid vibration type flowmeter is 23 mm.

Furthermore, the reason why the dimensions R, L, x, r, Tl, and P related to the dimensionless dimension of the flow meter are selected based on R for L, x, r, T1, and P is that the main flow of the jet is bent. This is because the angle (θ) of the section and the angle (θ ′) of the main return section of the return flow are substantially parallel.

Hereinafter, the measurement results of the fluid vibration type flow meter (2) will be described. FIG. 3 (b) shows the flow rate-instrument difference characteristics. As can be seen from this figure, high accuracy of ± 1.0% or less for large flow rates of 0.6m ³ / h or more, and ± 0.9% or less for low flow rates of 0.1 to 0.6m ³ / h. Therefore, a fluid vibration type flowmeter with high accuracy and sufficient durability for practical use has been obtained. Here, the transmission lower limit flow rate is about 65 l / h, and can be measured up to about 50 in Reynolds number, which is an extremely good result.

(Experimental example)

Hereinafter, the results of experiments performed by the inventors on the present application will be described.

Experimental Example 1 Configuration of Nozzle With the parameters other than the width wi of the nozzle suction part being the same as in the embodiment, the change of the flow rate-instrument difference characteristic when the width wi of the nozzle suction part was changed is shown in FIG. (I),
(B) and (c) are shown in FIG. In FIG. 4, the horizontal axis shows the width wi of the nozzle suction portion (dimensioned by the width wo of the nozzle ejection portion), and the vertical axis shows the ΔE value.
Here, the numerical value indicated by ΔE is a value indicating Emax (maximum value on the positive side) −Emin (maximum value on the negative side) in the characteristic curve, and is a numerical value that can determine the stability of measurement. (In testing the flow rate-instrument characteristic of a flow meter,
The test was performed for air up to a flow rate range of 5 m ³ / h. The reason for this is that a change in the Reynolds number when measuring another type of gas such as methane with respect to 3 m ³ / h, which is the upper limit flow rate value of the allowable standard, was considered. The flow rate-instrument difference characteristics at specific points (three points) in FIG. 4 are shown in FIGS. 3 (a), (b) and (c).

FIG. 3 (a) shows the flow rate-instrument difference characteristics of wi of 2.8 mm, that is, the nozzle width is expanded toward the downstream side, while FIG.
Wi is 3.2 mm, that is, the nozzle width is formed to be constant in the flow channel direction, and the flow rate-instrument difference characteristic of the parallel flow channel is shown in FIG. Although it became narrower toward the downstream side, the flow rate-instrument difference characteristic was shown.

Hereinafter, the results will be described. Nozzle suction part width wi
Is smaller than or equal to 2.8 mm, as shown in FIG. 3A, the error is very small from the small flow rate range to the large flow rate range, and good results are obtained. By the way, ΔE is
The value is below 1.2. As the width wi of the nozzle suction section is increased from this region, the error gradually increases, while the change tendency of the flow rate-instrument difference characteristic curve does not substantially change, as shown in FIG. Further, as shown in FIG. 3 (c), when the width wi of the nozzle suction part is increased, the error increasing tendency does not change and increases almost linearly. Here, when wi = 3.7, ΔE
The value is 2.9.

Δ when the width wi of such a nozzle suction part is increased
The change in E is shown in FIG. 4, and the area where ΔE is 3 or less is the area where wi / wo is 1.2 or less.

FIG. 4 shows the change in ΔE when the width wi of the nozzle suction portion is changed as described above, and the amount of pressure loss (the axis on the right side in FIG. 4; unit water column in mm) by this fluid vibration type flow meter. Indicated by broken lines. In the fluid vibration type flow meter having such a structure, the amount of pressure loss is largely controlled by the configuration of the nozzle (8), which is the portion where the flow path is narrowest.

As shown by the broken line in FIG. 4, the pressure loss decreases linearly with an increase in wi.

By the way, the maximum pressure drop defined by the Measurement Law is 3000
Since the water column is less than 20 mm at l / h, according to this standard, the lower limit value of the width wi of the nozzle suction part is defined. This lower limit is wi / wo = 0.9.

Summing up the above results, wi / wo is required to be in the range of 0.9 to 1.2.

(Another embodiment)

In the above-described embodiment, the enlarged wall portion (17) is formed in a straight line, but may have any shape as long as it is expanded downstream. Therefore, this wall is called an enlarged wall.

Note that, in the claims of the utility model registration, reference numerals are written for convenience of comparison with the drawings, but the present invention is not limited to the configuration of the attached drawings by the entry.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show an embodiment of a fluid vibration type flow meter according to the prior art and the present invention, FIG. 1 is a plan view of a flow measuring device incorporating the fluid vibration type flow meter of the present invention, and FIG. FIG. 3 is a diagram showing the relationship between the width of the nozzle suction unit and the flow rate-instrument difference characteristic. FIG. 4 is a diagram showing (A), (B), and (C). FIG. (6) ... storage part, (8) ... nozzle, (8w) ... linear inner wall, (9t) ... nozzle inlet end face, (11) ... nozzle ejection face, (12) ... flow path expansion Part, (13) ... throttle flow path part, (15) ... enlarged flow path inner wall surface, (16) ... main arc part,
(17) ... enlarged wall, (18) ... sub-arc, (20) ...
Target, (L2) ... Flow path in the nozzle.

Claims (3)

(57) [Scope of request for utility model registration] 1. A nozzle (8) having a nozzle ejection surface (11) orthogonal to a flow path is provided in the flow path, and the nozzle (8) has an ejection side with respect to the axis of the nozzle (8). And a symmetrical enlarged flow path inner wall surface (15) provided with a flow path enlarged portion (12) having a symmetrical enlarged flow path inner wall surface (15). A blocking target (20) is provided, and a throttle channel (13) having a channel width narrower than a rear end of the channel expansion (12) is further provided downstream of the channel expansion (12). The enlarged flow path inner wall surface (15) is provided with the nozzle ejection surface (11).
, An enlarged wall portion (17) smoothly connected to the main arc portion (16), and further smoothly connected to the enlarged wall portion (17), and the throttle on the downstream side. And a sub-arc part (18) connected to the flow path part (13), and the enlarged wall part (17) is arranged in the flow path direction in the target (2).
0) A fluid vibration type flowmeter configured to increase the flow path toward the downstream side to the position corresponding to the position of (0), wherein the flow path (L2) in the nozzle of the nozzle (8) is located at the nozzle inlet end face (9t). Connecting between the nozzle ejection surface (11),
The width between the two is formed between a pair of inner walls (8w) in which the width changes linearly, and the width of the nozzle internal flow path (L2) changes toward the nozzle ejection surface (11). And the width of the ejection part of the nozzle
wo, where wi is the width of the suction part of the nozzle, wi / wo is 0.9
Fluid oscillation type flow meter within 1.2 (except when Wi / wo = 1.0). 2. The nozzle straightening length, which is the distance between the nozzle ejection surface (11) and the nozzle inlet end surface (9t), is Nl, the radius of the main arc portion (16) is R, and the sub arc portion is L is the distance in the flow direction from the nozzle ejection surface (11) at the center of 18), x is the distance in the flow direction across the center of the sub-arc portion from the nozzle axis, and the sub-arc portion is The radius of (18) is r, the width of the target (20) is Tw, and the target (2) is
Assuming that Tl is the distance in the flow direction from the nozzle ejection surface (11) at the tip position of 0) and P is the width of the throttle flow path portion (13), the Nl, wo, R, L, x, r , Tw, Tl, and P are Nl / wo = 4.65 to 6.25 R / wo = 3.1 to 5.3 L / R = 1.5 x / R = 0.7 to 0.8 r / R = 0.45 to 0.56 Tw / wo = 1.56 to 2.00 Tl / 2. The fluid vibration type flow meter according to claim 1, wherein R = 0.94 to 1.1 P / R = 1.24 to 1.62. 3. A storage portion (6) for storing an inflow fluid is provided upstream of the nozzle (8), and the inflow fluid is substantially supplied to the nozzle inlet end face (9t) with respect to the storage portion (6). 3. The fluid vibratory flow meter according to claim 2, wherein the fluid flows in parallel.