High-Accuracy Flow Rate Measurement using Lamb Waves in Clamp-On Type Ultrasonic Flowmeter

This paper describes a high accuracy flow rate measure method in clamp-on type ultrasonic flowmeter. A path, so called "mean flow rate path" is a key compornent in high accuracy flow rate measurement. When a plate thickness is very small, ultrasonic is transmitted by Lamb wave in a condition that ultrasonic must be all reflected on surface by Snell's law. So in clamp-on type ultrasonic flowmeter, we can use a mean flow rate path and we can do high accuracy flow rate measurement. A characteristic of Lamb wave depend on a frequency of ultrasonic and a plate thickness. When a plate thickness is large, ultrasonic is transmitted by contorol of a frequency.