ICONE19-43184 TRANSIENT TWO-PHASE INTERFACIAL PARAMETER MEASUREMENTS USING ULTRASONIC PULSE-ECHO METHODS IN A NATURAL CIRCULATION LOOP

In this work, the flow measurement of a Two-Phase Natural Circulation Loop (2PNCL) was performed using a two-transducer pulse-echo technique. The ultrasonic system consists of a two-phase flow loop, a multiplexer, 3 panametric 10 MHz (6.4 mm) ultrasonic transducers, and a computer equipped with a Data Compuscope Digitizer, a motion controller, and Winspect Data Acquisition Software. Two transducers are attached on the two-phase flow test section separated by a distance of 3.9 cm and one transducer is mounted beneath the separation tank to measure the liquid level. The circular pipe test section is made of stainless steel with a length of 10.3 cm and an outer diameter of 13 mm with a thickness of 0.5 mm. Each transducer receives a pulse from the multiplexer and returns an echo which is received by the multiplexer. The Winspect software outputs an A-Scan which is an instantaneous display of the pulses and echoes. A C-Scan is obtained from continuous A-Scans at a scanning interval of 25 μs. Analysis of the pulse echo reflection is used to determine the water level in the separation tank. Flow measurements for two-phase flow regimes which include bubble properties, void fraction, and gas-liquid interface profile are obtained by analysis of the C-Scans. The results show flow regime transitions from bubble flow through to slug flow to an annular flow, with an increase in the inlet air flow rate.