21416 超音波流速分布式流量計測法に関する基礎研究 : 金属平板透過における超音波伝播特性(せん断流の計測,OS.4 流れの計測と制御)

抄録

The purpose of this study is to measure flow rates with high accuracy by using ultrasound. Experimental study has been conducted on ultrasonic properties which are necessary for the measurement. An automatic measurement system which can measure spatial-temporal sound pressure distributions has been developed. According to Snell's law, the ultrasonic propagation paths can be obtained on the basis of incidence angle, acoustic impedance, basic frequency of ultrasound, and material and thickness of metallic plate. However this law can't be applied to certain cases where an ultrasonic incident wave passes through a metallic plate and turns into a longitudinal wave, a shear wave and a Lamb wave. Consequently the ultrasonic propagation paths have been investigated experimentally at various angles of incidence and plate thickness. The most suitable incidence angle has been determined from the result of measurements, and flow rates will be measured.