Application of an Ultrasonic array sensor to air-water bubbly flow measurement

Abstract

The ultrasonic array sensor, which has been successfully applied in the field of medical diagnostics and non-destructive testing, was applied to single-phase and two-phase flow measurement. The applied array sensor has 128 elements on the surface and each of them has a basic frequency of 8 MHz. Flow measurement using the array sensor is very effective, because it can obtain the cross-sectional flow visualization images from outside the pipe without disturbing flows. In this study, the ultrasonic sound pressure distributions were measured by the sound field measuring system, and the ultrasonic beam characteristics and the grouping effects of elements were investigated from the sound pressure field. The velocity profiles of single-phase flows in a rectangular channel were measured with Ultrasonic Velocity Profiler (UVP) by scanning the parallel ultrasonic beam emitted from the array sensor. Furthermore, an ultrasonic array measuring system, which consists of a pulser/receiver, a multiplexer, an A/D converter and a signal processing device, was developed for the improvement of temporal resolution in bubbly flow measurement using the ultrasonic array sensor. Then the bubble distributions in the channel cross-section were confirmed by using the echo signals reflected from bubbles.