KR960015070B1 - Fluidic flowmeter - Google Patents

Abstract

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Description

Fluid flow meter

1 is a cross-sectional view through a flow meter in the main plane of the component.

2 is a cross sectional view along the centerline of the flow meter.

3 shows fluid motion in two states of a flow meter.

4 is a diagram showing transitions between the two states in FIG.

5 shows an alternative structure of the part of the device of FIG.

6A and 6B show an optional structure of the flow meter nozzle of FIG.

7 is a perspective view of a detector in the flow meter of FIG.

FIG. 8 shows a portion similar to that of FIG. 1 of an optional flow meter.

9 is a cross sectional view on the centerline of the flow meter of FIG.

10 shows various parameters of the device.

* Explanation of symbols for main parts of the drawings

11: cover plate 12: base plate

14, 29: discharge channel 19: elbow

22: inflow nozzle 23: splitter

24: required part 27: C type wall

28: feedback channel 37: remaining part

39: pin 53: vertex

The present invention relates to a flow meter and flow sensor in the form of a fluid oscillator arranged such that a frequency of oscillation can be measured or indicated an indicated flow rate.

The first said flow meter is described in GB-A-1 593 680, in which the fluid flows through the nozzle on the centerline of the compartment divided by the splitter on the centerline and the C-shaped member is each of the divided compartments. Split half of into an outer passage and a central zone. If the jet from the nozzle passes on one side of the splitter in contact with the nozzle, the jet flows into an outer passage that forms a feedback loop on the side of the compartment to reach within a transverse direction across the inlet of the nozzle. Therefore, the fluid is discharged from the nozzle toward the other side of the splitter so that the fluid flow is then switched to the other half of the compartment.

The number of switches is a function of flow rate. Transducers in the feedback conduit sense pressure and flow perturbation and provide an indication of volume flow rate. While all the components described above are located in the same plane, the outlets from each central zone extend out of the plane towards the same outlet from the device.

In GB-A-1 593 680, the compartment is divided by a generally V-shaped splitter with sharp vertices. The vertices of the splitter and the vertices of the wall dividing the feedback and output channels are all located at the same distance from the nozzle. The exhaust conduit is isolated from the splitter by the feedback channel. This is important because the first channel through which the jet passes therein becomes the feedback channel as the jet deviates from the centerline of the device. If the feedback channel is isolated from the splitter by the outlet channel, the main flow variation from the jet will first affect the outlet and the device is less sensitive than if the feedback channel is provided by the splitter sidewalls. Done. Another parameter affecting the sensitivity is the length of the feedback channel and is lengthened in the present invention since the feedback channel must pass around the discharge channel.

It is known that the vertex of the splitter and the relative position of the wall separating the feedback and output channels are important. According to the invention, there is provided a fluid flow meter as described in claim 1. The peak between the discharge channel and the feedback channel measured along the centerline of the meter from the inlet of the splitter and the nozzle is preferably 1 to 4 times the nozzle width. It was found that the final range provided the greatest sensitivity at the lowest Reynolds number combined with a uniform response to different Reynold numbers. The distance from the apex between the discharge channel and the feedback channel measured along the centerline of the instrument from the inlet of the nozzle is preferably 5,6 to 12.0 times the nozzle width.

An optional feature of the present invention lies in the passage of the feedback channel which returns back to the plane from the common plane described above. This allows the discharge conduit to be present in the common plane as it passes from the inside of the feedback loop to the outside and to be combined into a single discharge conduit outside the splitter while still in the plane. In this arrangement, the feedback channel can extend on both sides of the other pressure transducer and the output of the transducer indicates the number of flow changes. Another factor affecting sensitivity is the length of the feedback channel and the shorter the channel, the greater the sensitivity and the channels must extend around the discharge channel in the common plane by directing the channels out of the common plane. Try to be shorter than the channels you are using. This arrangement also helps the outflow of air from the feedback channel.

Potential experiments have found that vortex forms in the volume in front of the splitter. The direction of rotation of the eddy changes as the fluid changes direction as it moves between the sides of the splitter. Another optional feature of the present invention assists in the shaping and stability of the eddy by providing a requirement in the nose of the splitter. Various forms of requirements may be used and the best form found is a smoothly curved requirement that is joined into the remainder of the splitter by a smoothly curved boundary. The depth of the required portion is preferably of the same grade as half the width of the nozzle.

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 through 4, the flow meter consists of a flat cover plate 11 and a base plate 12 and a fluid flow passage extends through the entire depth of the base plate 12. And together with the discharge passage 14 in the upper surface area of the base plate 12.

The flow meter is symmetric about the center line 15 and on the center line is a split splitter 23 in which the inlet 21, the nozzle 22, and the request portion 24 are formed at the end contacting the nozzle, and the side wall of the splitter is located. Is smoothly curbed into the desired itself. The depth of the required portion is generally equal to half the nozzle width. The zones on both sides of the centerline 15 between the nozzle 22 and the splitter 23 are loaded by the C-shaped wall 27 into the outer passage, which forms the feedback channel 28 and the inner region 24. The inner zone 29 then directs the discharge passage 14 extending through the depth of the base plate to the same outlet 31 on its side of the flow meter. Each C-shaped wall to the vertex 53 or splitter is located in front of the splitter and is spaced outwardly from the splitter and the outer surface of the C-shaped wall thus forms an effective extension of the required wall. The feedback channel 28 passes around the discharge passage 14 from the nozzle 22 to its outlet 19 in the direction of traversing the jet.

The fluid flows through the entire depth of the base plate in the inflow passage 13 and along the circumference of the elbow 19 to the first compartment 21 in the upper surface zone. The elbow 19 is included even if there are no obstructions that help smooth disturbances upstream of the instrument and prevent the inlet passage from being entirely located within the common plane of most other parts.

Fluid flows from the compartment 26 through the nozzle 22 along the centerline of the flow meter and is split by the splitter 23. When the fluid from the nozzle 22 is selectively passed to one side of the splitter 23, the circumference is formed in one direction in the extension zone provided by the proximal end of the request portion 24 and the C-shaped wall 27 and the pressure is Optionally set in outlet 19 or corresponding feedback channel 28 to allow fluid to be discharged from the nozzle towards the other side of the splitter and reverse the state of the flow meter. The state is vibrated and the frequency is measured by the flow rate. Manometer tubes guided from the feedback channel or from the pressure transducers in the feedback channel (see FIG. 7) can be calibrated to respond to pressure changes and to indicate the flow rate from the number of times measured. It has been found in the design of the present invention to provide a linear relationship between the number of pressure changes and the fluid flow even at low flow rates. The use of the transducer in this way avoids the problems caused by gas bubbles or impurities in the pressure gauge that require blbeeding or cleaning. The pressure transducer can be replaced with a flow transducer and the flow transducer can instead be located in the request 24 to indicate the reversal of the eddy. The flow transducer may use an increase in the ultrasonic non-clinical flow or multiples of the Doppler effect and measure heat loss to the flow fluid or heat obtained from the flow fluid. Consider first the case of a conventional convex "nose" portion in the splitter. As the jet is pushed from one side of the flow path to the other, the pressure in the nose increases. Pressure is at a minimum at the center line of the nose section. Most of the fluid is directed in the opposite direction to the relatively high stagnation pressure at this point. The energy required in the feedback pulse to drive the jet across the passage is relatively high.

If the case of concave splitter nose is considered, the following can be observed.

The "stallion point" where the flow impinges on the vortex is not located at the center line.

The circulation of the flow around the vortex must produce a "magnus effect", a force that tends to move the vortex in a direction that obstructs the previous active feedback path. The vortex was observed to move at a low flow rate of 2 liters / hour, equivalent to a Reynolds number of 50 in this method.

4A to 4E show a change in the flow passing through the other side of the splitter in the flow of the fluid preferentially through one side of the splitter 23. In FIG. 4A, the fluid preferentially flows to the left side of the splitter 23, forming a clockwise vortex at the request portion 24. In FIG. The fluid flowing around the left side of the feedback passage 28 increases the pressure at the outlet of the feedback passage as shown in FIG. 4B and therefore promotes the flow of fluid from the nozzle to the right as shown in FIG. 4C and shown in FIG. 4D. Reverse the vortex as shown, and let the flow preferentially flow to the right of the feedback path as shown in Figure 4E.

In Figures 1 to 4, the ends of the C-shaped wall surfaces adjacent to the required portions are shown as sharp protrusions. 5 shows an alternative arrangement with fins 39 (perpendicular to the plane) forming a small space 38 along the apex by blunt ends forming the rest of the protrusions. The fin 39 helps to form an extension of the requirement wall in the same way as the solid C-shaped wall in FIGS.

Figures 6a and 6b show an alternative nozzle: Figure 6a forms a quadrant at the inlet side of the nozzle. The inlet chamber in the upper surface area of the base plate 12 is parallel to the top of the nozzle, and the width of the nozzle is about one quarter of the inlet passage width, and the inlet surface is a quadrant of the circle 34 shown in FIG. Is formed. 6B shows the nozzle with the first tapered portion 51 leading to the parallel plane portion 52. Orifice flow meters are known to provide improved linearity between pressure changes and fluid flow at low flow rates.

7 shows a pressure transducer which forms a piece of piezoelectric material 32 at the wall of the splitter adjacent to the apex of the splitter, which is connected by a cable 33 to the detection and indication system and the cable is connected to the pressure in the fluid flow. The change in voltage in the piezoelectric material produced by the change is communicated to the detection and indication system. The signal from the piezoelectric material 32 travels to the pulse counter via an analog / digital converter, and all accessories are powered from an external power source and are primarily formed as an integrated circuit. In an alternative arrangement, the signal from the piezoelectric material 32 passes through the amplifier to an electro-magnetic pulse counter and indicator, from which it travels to an energy store that powers the amplifier as required.

In other embodiments of FIGS. 8 and 9, the flow meter is in the axial plane with most of the parts having an inlet 21 and an outlet 31A on the central axis. There is an intermediate plane in the direction perpendicular to the drawing, the axial plane being the plane of the drawing and transverse to the intermediate plane. Only feedback conduit 28A extends out of the axial plane (ie has an extension perpendicular to the axial plane), both sides of the splitter 23 to and from the axial plane in the region of the nozzle Taking the flow of fluid from, the outlets of the feedback conduits 28A extend in the direction transverse to the nozzle 22 as in the above-described embodiment. The arrangement makes it possible for the two feedback conduits 28A to run parallel to one another at a point 35 in the plane displaced from the axial plane, where the planes differentially record the pressure difference between the conduits. Separated by 36. The displacement of the feedback conduit 28A from the axial plane also allows the outlet passage 14A to be maintained in the axial plane and is shorter than the conduits through which the feedback conduit 28A passes right around the outlet passage. This makes it possible to increase the frequency for a given flow rate. The embodiment of Figure 8 is a suitable embodiment of the embodiment of Figures 1-4. 10 shows various parameters of the device; a is the distance of the axis from the nozzle to the lips of the required portion; c is the axial distance from the nozzle to the end of the C-shaped wall (pin 17) adjacent the demanding portion; d is the nozzle width. In all specific descriptions, a is greater than C. It is preferable that coefficient (a-c) / d is at least 1, and 4 is the best. The coefficient c / d is preferably at least 5.8 and 12 or less is suitable.

The present invention is a special device for a calorimeter, in which the flow of heat is indicated by the measurement of the different temperatures of the flow fluid and by the measurement described above.

Claims (4)

A splitter 23 positioned on the centerline with a centerline 15, an inlet nozzle 22 in the direction along the centerline for the fluid whose flow rate is to be measured, and a vertex 24 facing the nozzle. And a centerline, each side of the compartment on the side of each center plane divided into a feedback passage 28 and an outlet passage 29, 14 having a vertex 53 therebetween; The feedback passage 28 is a flow flowmeter extending from the upper portion 53 of the splitter to the position 19 at the mouth side of the nozzle, wherein the distance a from the mouth of the nozzle 22 to the splitter 23 is A flowmeter, characterized in that it is closer than the distance from the mouth of the nozzle to the vertex 56 between the feedback passage and the outlet passage. The flow meter according to claim 1, wherein the difference in distances is greater than the width d of the nozzle. The flow meter of claim 1, wherein the feedback passages extend in a direction perpendicular to the second plane through a centerline transverse to the intermediate plane. The flow meter according to claim 1, comprising a request portion 24 in an end portion of the splitter facing the nozzle.

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