Flow Pattern Classification in Water-Air Vertical Flows Using a Single Ultrasonic Transducer

Researchers around the world have proposed different methodologies for flow-pattern identification in multi-phase flows. The most common explored techniques are based on optical imaging, pressure fluctuation, electrical impedance, radiation absorption, and ultrasound. Because the ultrasonic technique is relatively low in cost, easy to conduct, accurate, nonintrusive, and suitable for opaque systems, this paper presents a flow-pattern classifier based on ultrasound for two-phase vertical water-air flows. It is based on the coefficient of variation of the energy of the pulses reflected by the dispersed phase. Also, it uses just one ultrasonic transducer. An experimental plant was built to develop two-phase water-air flows to evaluate the proposed technique performance by comparing it to the visual analysis of the recorded image of the flow. A total of 102 different experimental points were collected and evaluated. The results have shown that the method was capable to distinguish dispersed bubbles, slug and churn flow patterns.