Real-Time Cross-Sectional Averaged Void Fraction Measurements in Vertical Annulus Gas-Liquid Two-Phase Flow by Neutron Radiography and X-ray Tomography Techniques

A Real-Time Neutron Radiography (RTNR) system and a High Speed X-ray Computed Tomography (X-CT) system are compared for measurement of two-phase flow. Each system is used to determine the flow regime, the instantaneous cross-sectional averaged void fraction, and the time averaged void fraction in a vertical annulus flow channel. A standard optical video system is also used to observe the flow regime. The annulus flow channel is operated as a bubble column and measurements obtained for gas flow rates form 0.0 to 30.0 1/min. The flow regimes observed by all three measurement systems through image analysis shows that the results agree well with each other. Both techniques show that the time averaged and cross-sectional averaged void fraction increases with increasing superficial gas velocity. Time and crosssectional averaged void fractions determined by the RTNR system agree within 4% with those determined by the High Speed X-ray CT technique.