| 摘要 |
PURPOSE:To make the directivity of an ultrasonic wave which leaks and is propagated in piping sharp, to prevent the mode wave of a harmful component from being generated, and to obtain an ultrasonic wave transmitter-receiver with improved measurement accuracy by specifying the opening length of a wedge member for fitting an ultrasonic vibrator. CONSTITUTION:When ultrasonic wave transmitter-receivers 1 and 2 send out ultrasonic waves from an upstream side to a downstream side, the received wave of an arrival ultrasonic wave is sent to a timer means 13 through a receiving circuit part 12 and the propagation time is stored in a 1st memory 14. Then when a transmission/reception switching part 10 outputs an ultrasonic wave in the opposite direction, the propagation time of the received signal is stored in the memory 14 and respective data are sent to an arithmetic means 17 to compute a flow rate which is displayed on a display means 18. At this time, when the radiation opening length of wedge members 1A and 2A is set to b=18lambda, the angle beta of the direction of a 1st zero radiation angle is nearly 3.2 deg. and the directivity is + or -1.6 deg.. In this case, a propagated wave in a 52 deg. direction is received unless the angle is 38 deg. on the reception side when the angle PHI0 of incidence is 47 deg.. In this case, almost no S0 mode is generated and a harmful wave which differs in angle of refraction is hardly generated, so the ultrasonic wave from the transmission side is received effectively at an angle theta0 of refraction as it is which is expected initially.
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