Quantitative void fraction measurement method by neutron radiography and applications to two-phase flow researches

Quantitative void fraction measurement method by neutron radiography was developed using a neutron absorber grid based on an umbra method. The cross-sectionally averaged void fraction for various flow patterns in air-water two-phase flow in a tube was measured quantitatively. Uncertainty analyses were carried out for the measured values and the accuracy of the measurement was discussed for each flow pattern. Experimental results agree well with the prediction by drift flux model. The quantitative measurement method was applied to two-phase flow in a concentric annular tube, a tube with a spiral wire, a rod bundle, a capillary tube and a plate fin heat exchanger. The CT reconstruction method was applied to measure the quantitative void fraction distributions in the cross section.