JPH059725B2 - - Google Patents

Description

TECHNICAL FIELD The present invention relates to a vortex flowmeter that utilizes a Karman vortex generated by a vortex generator disposed in a fluid.

Prior Art FIG. 1 is a schematic configuration diagram for explaining an example of a conventional vortex flowmeter. In the figure, 1 is a fluid flow path to be measured through which a fluid to be measured flows, 2 is a vortex generator, and 3 is a vortex generator. An ultrasonic transmitter disposed on a side wall of the measurement fluid flow path 1 and intersecting with the vortex generator 2; 4 is an ultrasonic receiver disposed opposite the ultrasonic transmitter 3; As is well known, when a columnar vortex generator 2 is inserted into a fluid flow path 1, the flow separates on both sides of the vortex generator 2, and regular vortices or vortices are created alternately on the downstream side of the vortex generator. A Karman vortex is generated and fluid displacement occurs in the direction of the arrow. Since the number of Karman vortices generated is proportional to the flow velocity or flow rate of the fluid, the flow rate can be measured by counting the number of Karman vortices. Conventionally, in order to count this Karman vortex, an ultrasonic transmitter/receiver is disposed across the Karman vortex, and the frequency modulation or phase modulation of the ultrasonic wave from the ultrasonic receiver 3 is converted into an ultrasonic wave. Although the receiver 4 was used for detection, disturbances in the flow of the fluid to be measured occur due to external noise, such as scattering of ultrasonic waves by Karman vortices, reflection of ultrasonic waves on pipe walls, etc., and this causes measurement errors. It was also a contributing factor.

Purpose The present invention has been made in view of the above-mentioned circumstances, and relates to a vortex flowmeter that can accurately measure Karman vortices without being affected by external noise or the like.

Configuration FIG. 2 is a cross-sectional configuration diagram for explaining one embodiment of the present invention, and in the figure, parts that have the same effect as in FIG. 1 are designated by the same reference numbers as in FIG. 1. It has been done. As is clear from FIG. 2, the invention does not provide an ultrasonic transmitter/receiver directly on the side wall of the fluid flow path 1 to be measured. In addition to providing ports 5 and 6, these inlets 5 and 6 are communicated through a straight tubular communication path 7, and the flow path area of the intuitive communication path 7 is smaller than the flow path area of the inlet ports 5 and 6. For example, an ultrasonic transmitter/receiver 3,
4 detectors are arranged. Note that if an ultrasonic detector with a cone is used as the ultrasonic transmitter/receiver, the Karman vortex can be measured with higher accuracy.

Effects As is clear from the above explanation, according to the present invention, the pressure extracted from the pressure outlet is effectively converted into flow velocity, and the fluid in the straight tubular communication passage is disturbed by noise from the outside. It moves in the direction of the arrow in a substantially laminar flow without being distorted, and its moving speed is high, so the number of Karman vortices can be measured with higher accuracy.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram for explaining an example of a conventional vortex flowmeter, and FIG. 2 is a cross-sectional configuration diagram of a vortex flowmeter according to the present invention. 1... Fluid flow path to be measured, 2... Vortex generator, 3...
...Ultrasonic transmitter, 4...Ultrasonic receiver, 5, 6...
...Introduction port, 7...Straight tubular communication path.

Claims (1)

[Scope of Claims] 1. A vortex generator disposed in a fluid path to be measured, an introduction pipe opening on both side wall surfaces of the flow path near the vortex generator, and a predetermined portion communicating with the other end of the introduction pipe. It consists of a long straight communicating tube, and an ultrasonic transmitter/receiver installed at both ends of the communicating tube to detect alternating flow caused by a vortex flowing inside the communicating tube, and the communicating tube has a large diameter near both ends. The pipe is continuously reduced from the large-diameter portions at both ends to form a small-diameter straight pipe section with a constant cross-sectional shape, and the flow rate is detected from the number of fluctuations per unit time of the alternating flow in the communicating pipe. Vortex flow meter. 2. The vortex flowmeter according to claim 1, wherein the detector is an ultrasonic detection element with a cone.