REAL-TIME CROSS-SECTIONAL AVERAGED VOID FRACTION MEASUREMENTS IN VERTICAL ANNULUS GAS-LIQUID 2-PHASE FLOW BY NEUTRON RADIOGRAPHY AND X-RAY TOMOGRAPHY TECHNIQUES

A Real-Time Neutron Radiography (RTNR) system and a high speed X-ray C omputed Tomography (X-CT) system are used to determine the how regime, the instantaneous cross-sectional averaged void fraction, and the tim e averaged void fraction in a vertical annulus flow channel. A standar d optical video system is also used to observe the flow regime. The an nulus how channel is operated as a bubble column and measurements are obtained for gas flow rates form 0.0 to 30.0 l/min. The flow regimes o bserved by all three measurement systems via image analysis shows that the results agree well with each other. Both the RTNR and the X-CT sy stems show that the time averaged and cross-sectional averaged void fr action increases with increasing superficial gas velocity. Time and cr oss-sectional averaged void fractions determined by the RTNR system ag ree within 4% with those determined by the high speed X-ray CT techniq ue.