| 摘要 |
PURPOSE:To measure the sonic velocity of the fluid in piping with high accuracy without making contact with the fluid, by a method wherein an ultrasonic wave is allowed to be obliquely incident from the outer wall of the piping and the phase speed and group speed caused by the ultrasonic wave of the pipe wall part at the time of measurement are measured and operated according to a specific formula. CONSTITUTION:After ultrasonic transmitter-receivers 1, 2 are respectively fixed and mounted to piping 3 on the upstream and downstream sides thereof along an ultrasonic wave propagation line, an ultrasonic wave is allowed to be obliquely incident from the outer wall of the piping 3 to measure the phase velocity Vp and group velocity Vg due to the ultrasonic wave of the pipe wall part at the time of measurement. Next, almost simultaneously with measurement, the differences DELTAtu, DELTAtd between the times before the ultrasonic waves respectively oscillated from the upstream side to the downstream side and from the downstream side to the upstream side respectively propagate through the pipe wall or the fluid in the piping to be received and the times before the ultrasonic waves propagate through the fluid in piping over N-processes (N=2, 4, 6...) to be received are respectively measured. Subsequently, on the basis of these measured values, a preliminarily specified predetermined function, that is, formula is operated to make it possible to specify the sonic velocity C of the fluid 4 in the piping. By this method, the sonic velocity of the fluid can be measured with high accuracy without making contact with the fluid.
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