| 摘要 |
PROBLEM TO BE SOLVED: To provide a vortex flowmeter which is improved so as to suppress the changes in ultrasonic level to a small degree at the time of the transmitting and receiving of ultrasonic signals. SOLUTION: Transmission ultrasonic waves transmitted from an ultrasonic transmitter 24 arranged at a measurement pipeline 13 is changed in propagation time by Karman vortexes and received as reception ultrasonic waves by an ultrasonic receiver 25 arranged at the measurement pipeline in a position facing the ultrasonic transmitter. In this vortex flowmeter which measures the flow rate of a fluid to be measured flowing through the measurement pipeline through the use of the above-mentioned arrangements, the radius r of a piezoelectric element contained in the ultrasonic receiver is at least selected so as to be determined by an equation; K=2SIN[π(τ<2> +r<2> )<1/2> -τ}/λ. Here, K is the coefficient of sound pressure indicating the ratio of reception sound pressure to transmission sound pressure,τis the distance between the ultrasonic transmitter and receiver, andλis the wave length of the transmission ultrasonic waves.
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