Void fraction along a vertical heated rod bundle under flow stagnation conditions

Axial void fraction distributions were measured in a vertical cylindrical channel with a four-rod heated bundle under flow stagnation conditions. The development length for the void fraction profile was measured. It was observed that the void fraction profile does not always increase progressively along the channel, but peaks where most of the coalescence takes place. The ability of currently used drift-flux correlations to predict such behavior is questioned by the present experimental results. ((orig.))