Verification of using a single void fraction sensor to identify two-phase flow patterns

This paper investigates methods using the signals detected by a single void fraction sensor to identify four kinds of typical vertical, cocurrent, upward, two-phase tube flow patterns. By analyzing 100 sets of time-varying void fraction signals acquired from an impedance device in an air-water two-phase loop, the results of the various methods are evaluated and demonstrated. With the high-frequency contribution fraction (HFCF) criteria, the success rate is 81%. An auxiliary criterion (the void fraction criterion) is proposed to increase the success rate to 92%. The results and the criteria from this study are compared with earlier studies. From the comparison, the applicability of the HFCF criterion to a system in which void fraction can be measured directly is verified