JPS62214321A - Vortex flowmeter - Google Patents

Abstract

PURPOSE:To obtain a flowmeter which has superior linearity over a wide flow rate range by arranging a tubular body having pressure intakes where pressure variation due to a vortex is admitted on the downstream side of a vortex generating body so that the tubular body crosses a flow. CONSTITUTION:The vortex generating device 2 arranged opposite the flow in a flow passage 1 is constituted by arranging successively an upstream-side vortex generating element 2a in an isosceles triangle shape, a T-shaped downstream-side vortex generating element 2b which has a little bit lower vortex frequency than it, and a flat plate 2c which is arranged between them at specific intervals. The tubular body 3 is supported penetrating the wall of the flow passage 1 on the downstream side of the vortex generating body 2 while crossing it. The tubular body 3 has both end surfaces closed and a tube body 32 having plural pressure intakes 33 is fixed communicating it at right angles. Then, variation pressure is admitted into the pressure intakes 33 to cause fluid displacement, which is detected as an ultrasonic modulated wave. A vortex with superior linearity is obtained by interference due to a difference in vortex frequency between the elements 2a and 2b.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a structure for detecting a vortex signal with excellent S/N in a vortex flowmeter.

The applicant of the present application, in Japanese Patent Application No. 58-60333,
As shown in the figure, a tubular body 3 is disposed behind the vortex generating body 2 in a direction crossing the vortex generating body 2, and at least one pair of tubular bodies 3 is arranged at a predetermined interval in the axial direction of the tubular body 3. We have proposed a vortex flow meter in which a pressure adjustment hole 31 is bored. This flowmeter focuses on the fact that the fluid is rectified by applying a fluctuating pressure inside the tubular body 3 to cause fluid fluctuations, and introducing this fluid fluctuation into the tubular body 3, which has a relatively small flow area. This is what I did. In this way, compared to the case without a tubular body, even turbulent vortices included in the flow in the direction of the flow path will not be detected, and noise components mixed in the detection signal will be reduced, resulting in a lower S/N ratio. We were able to obtain an excellent detection signal. Detection of already generated vortex signals can be improved by the method described above, but the vortex generator also has an isosceles triangular shape with an acute angle to the flow direction A, as shown in Japanese Patent Publication No. 55-40804. Set up your body,
By sequentially arranging independent flat plates behind this generator at desired intervals, it was possible to amplify the vortex and generate a strong and stable vortex.

However, according to the conventional technology described above, by means of generating a strong and stable vortex and means of detecting the generated vortex with an excellent S/N ratio, it is possible to achieve an unprecedented stable vortex flow rate. However, in order to measure the flow rate over a wider range, it is necessary to obtain a stronger vortex signal and a stroke meter.
Corresponding to the above, it was also necessary to maintain a constant value over a wide range of hull numbers. Furthermore, in the above-mentioned Japanese Patent Publication No. 55-40804, it has a positive instrumental error characteristic in a small flow area, so although it is a stable vortex generator, it is unsatisfactory for flowmeters that are required to measure a wider range. there were.

The present invention has been made to solve the above-mentioned problems, and has an advantage in that the pressure introduction holes 31 of the prior art in the vortex detection means are arranged in the axial direction of the tubular body 3. On the other hand, focusing on the fact that the vortex generated from the vortex generator is separated from the vortex generator as a vortex column three-dimensionally, pressure introduction holes are arranged in the direction of the vortex column to introduce effective pressure fluctuations. At the same time, in order to improve the unique characteristics of the vortex generator and obtain a flowmeter with excellent linearity over a wide range of flow rates, we focused on the vortex frequency ratio of the individual vortex generating elements that make up the vortex generator. This solves the problems of the prior art.

Figure 1 is a diagram for explaining the present invention in detail, and in Figure 1,
Components having the same structure as the prior art shown in FIG. 3 are given the same reference numerals. The vortex generating element 2 includes an isosceles triangular vortex generating element 2a which is an upstream vortex generating element, a T-shaped vortex generating element 2b disposed on the downstream side, and a flat plate 2c disposed in the middle thereof. are sequentially arranged so that the representative lengths d face each other. A tubular body 3 that introduces pressure fluctuations due to the vortex into the wake of the vortex generator 2 arranged in this manner is supported so as to penetrate through the channel wall 1 so as to intersect with the vortex generator 2 . FIG. 1(C) shows details of the tubular body 3, in which a pair of tubular bodies 32 are fixed to the tubular body 3 in communication with each other orthogonally. Note that the end face of the pipe body is closed, and a plurality of pressure introduction holes 33 are opened to the wall soil of the straight pipe. The fluctuating pressure is introduced into a pair of pressure introduction holes 33, and a corresponding fluid displacement occurs as indicated by the arrow. When detecting this fluid displacement as an ultrasonic modulation signal, a sound absorbing material 34 such as a nonwoven fabric is attached to the inner wall of the tube body 32 in order to prevent disturbance of ultrasonic waves contained in the fluid from entering. FIG. 1(D) shows a perspective view thereof, and the notch 35 is provided so as not to close the pressure guiding hole 33. On the other hand, the vortex generator 2 is a vortex generator 2a.
The vortex frequency ratio of the vortex generating element 2b to the vortex frequency of 0.
7 to 0.9 is given. The plates 2c are juxtaposed between them, each with tx+tel t.

A gap of t to t is given and selected to be 0.1 d to 0.4 d. The vortex flowmeter of FIG. 1 configured in this way can obtain vortices with excellent linearity due to interference due to differences in vortex frequencies between the vortex generating elements.

That is, since the vortex generation frequency of the vortex generation element 2b on the downstream side is low, the vortex circulation is strong and dominates the high Reynolds number region, and the difference in vortex frequency generated at a low Reynolds number is the difference between the vortex generation elements 2a and 2.
The vortex frequency in the low Reynolds number region is regulated by interference with the vortex of the vortex generating element 2a generated in the gap between b.

The vortex that separates from the vortex generator described above flows down as a vortex column parallel to the axis of the vortex generator, so pressure fluctuations tend to follow this, so the introduced pressure difference is also large and averaged out. .

The flat plate 2C is used to introduce the vortex generated by the vortex generating element 2a between the gaps tt and tt3, thereby producing an amplifying effect of growing the vortex. In addition to the configuration shown in Figure 1 (A), the vortex generator can be constructed by combining a triangular prism, a trapezoid, and a flat plate as shown in Figure 2 (A).
), (B), and (C), and it is effective by adding the above conditions to these configurations.

As described above, according to the present invention, the vortex generation frequency has a wide range and has excellent linearity that is proportional to the flow rate. Furthermore, a stable eddy signal is obtained, while.

Even in vortex detection, a stronger fluctuating differential pressure can be obtained, so that a vortex flow meter with an extremely wide flow rate measurement range can be obtained, including both methods.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the vortex flowmeter according to the present invention, in which (A) is a side sectional view, (B) is a sectional view taken along the line B-B in (A), and (C) is a sectional view taken along the line B-B of (A). Detailed view of the tubular body. (D) is a detailed view of the nonwoven fabric, FIG. 2 is a sectional view showing another embodiment of the vortex generator, and FIG. 3 is a view showing an example of a conventional vortex flowmeter. 1... Channel, 2... Vortex generator, 3... Tubular body, 4
... Ultrasonic oscillator, 5... Ultrasonic receiver, 32...
- Pipe body, 33...Pressure introduction hole, 34...Nonwoven fabric. Patent applicant Oval Equipment Industry Co., Ltd. wJ j
Figure (B) 2 (C) (D) 2nd (A) (B) 3rd (C) Figure (B)

Claims (8)

[Claims] (1) At the rear of the vortex generator disposed in the flow path facing the flow, it communicates orthogonally with a tubular body supported by passing through the flow path wall so as to intersect with the vortex generator. A pair of tubular bodies are fixedly installed, a pressure introduction hole is perforated in the tubular bodies, and the displacement of the fluid flowing inside the tubular body is detected by the vortex fluctuating pressure introduced from the pressure introduction hole. vortex flow meter. (2) A patent characterized in that the above-mentioned vortex generating body is characterized in that vortex generating elements each having an isosceles triangular or T-shaped cross-sectional shape with an apex on the flow path axis are arranged at predetermined intervals. A vortex flowmeter according to claim (1). (3) The above-mentioned vortex generating body is characterized in that vortex generating elements each having an isosceles triangular cross-sectional shape, a flat plate shape, and a T-shaped cross-sectional shape with the apex on the flow path axis are sequentially arranged at predetermined intervals. A vortex flowmeter according to claim (1). (4) The above-mentioned vortex generating body is characterized in that vortex generating elements each having an isosceles triangular or ladder-shaped cross-sectional shape with an apex on the flow path axis are arranged at predetermined intervals. A vortex flowmeter according to scope (1). (5) The above-mentioned vortex generating body is characterized in that vortex generating elements each having a cross-sectional shape having an isosceles triangular shape, a flat plate shape, and a ladder shape with an apex on the flow path axis are sequentially arranged at a predetermined interval. A vortex flowmeter according to claim (1). (6) The vortex generating body has a vortex frequency ratio of an isosceles triangular vortex generating element disposed on the upstream side and a T-shaped or ladder-shaped vortex generating element disposed on the downstream side. 0 as a standard
．． 7 to 0.9. The vortex flowmeter according to any one of claims (2) to (5). (7) The fluid displacement is detected as an ultrasonic modulation signal of a fluctuating flow between an ultrasonic oscillator and a receiver disposed at both ends of the tubular body. 6) The vortex flow meter according to any one of paragraphs. (8) Any one of claims (1) to (7), characterized in that a sound-absorbing material such as a nonwoven fabric is provided inside the inner walls of a pair of tubes that communicate orthogonally with the tubular body. Vortex flowmeter as described in section.