P049

Ultrasonic Measurement Method for Transversal Component of Water Flow Velocity

A0119 Kageyoshi Katakura Koden Electronics Co.,Ltd.

A0120 Phonebanhdith Alain ISMRA, ENSI de CAEN, Institute des Sciencesde la Matiere et du Rayonnement

There are many ultrasonic methods for flow speed measurement. These

methods are grouped into two categories: reflection mode and

transmission mode configurations.

In the first category, ultrasound Doppler systems are used. In the

system, the velocity component along the beam axis is derived from the

observed frequency shift in back scattered sound wave. When

propagating media is pure, the back-scattered sound wave is very weak.

Therefore, these methods will not detect flow speed of pure water or

wide ocean flow.

In the second category, through transmission methods are used. In the

method, ultrasound wave propagates through the current flow not with

orthogonal direction to the flow direction but with an inclined

orientation.

Two-way transmissions, one is toward downstream and other is toward

upstream, give two propagation delay times. Difference between the

two delay times provides the flow velocity component along the sound

propagation direction.

This method provides water flow velocity component along the sound

propagation path. Therefore, when the flow direction is unknown, this

method will not show true current flow volume through the plane of the

sound propagation.

We propose a method to measure flow velocity perpendicular to the

sound propagation path. Proposed method provides true current flow

volume regardless to the flow direction. This paper will show

detailed procedures of the method and some results taken from

experiment in river. .