| 摘要 |
A Doppler type ultrasonic flowmeter has an ultrasonic transmitting means for emitting ultrasonic pulses from an ultrasonic transducer into a fluid pipe, a flow velocity profile measuring means for receiving an ultrasonic echo reflected from a measurement region in the fluid pipe thereby to measure a flow velocity profile of a fluid to be measured, a fluid flow rate computing means for calculating the flow rate thereof on the basis of the flow velocity profile of the fluid to be measured, and a frequency selecting and setting means for automatically selecting a fundamental frequency of an ultrasonic wave that causes a resonant transmission phenomenon to take place from the ultrasonic transducer. The frequency selecting and setting means controls the operation of the ultrasonic transmitting means such that an ultrasonic wave of a selected optimum frequency is emitted from the ultrasonic transducer. This arrangement makes it possible to provide a highly versatile Doppler type ultrasonic flowmeter that permits simple, easy, contactless, precise and highly accurate measurement of the flow rates of fluids to be measured that are flowing in various fluid pipes.
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