Development of pulse ultrasonic doppler method for flow rate measurement in power plant. Multilines flow rate measurement on metal pipe

Ultrasonic Doppler method for a flow metering system has been developed. The method has the capability to obtain instantaneous velocity profiles along the ultrasonic beam. Our purpose is to apply the ultrasonic Doppler method to a flow rate measurement of feed- or recirculation- water in power plants. The principle of the flow measurement method is based on the integration of an instantaneous velocity profile over a pipe diameter. Hence, it is expected to eliminate installation problems such as entry length, also to follow transient flow rate precisely by increasing ultrasonic trans-ducers. In this paper, we report that the errors are less than 1% just below a bend and sudden expansion pipe employing three measuring lines. And then, for constructing a basic system of a flow rate measurement in power plants, a transmission of ultrasound through a metallic wall is investigated, at first. Afterward, since there is no ultrasonic reflectors in the feedwater in power plants, cavitation bubbles are induced as ultrasonic reflectors and the results are appeared that cavitation bubbles are effective when the pipe material is metallic. (author)