| 摘要 |
PROBLEM TO BE SOLVED: To provide a flow rate measuring method preferably to flow rate measurement for fluid moving in a tubular body especially, with a large outer diameter that can easily design a flowmeter and install it and then stably measure a flow rate even when environment temperature varies. SOLUTION: By transmitting an ultrasonic wave toward the center axis of the tubular body with each of two detectors for ultrasonic generation generating ultrasonic waves with mutually different frequencies arranged along the outer direction of the tubular body, an ultrasonic wave with an frequency of the difference between the two ultrasonic waves transmitted from each of the detectors for the ultrasonic generation is generated with parametric effect very near to the center axis of the tubular body. The flow rate of the fluid moving in the tubular body is measured by using this ultrasonic wave. COPYRIGHT: (C)2003,JPO
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