Measurement of three-dimensional void fraction distribution in two-phase flow through sphere-packed bed by X-ray CT

Odaira, Naoya*; Ito, Daisuke*; Ito, Kei*; Saito, Yasushi*; Imaizumi, Yuya ; Matsuba, Kenichi  

Two-phase flow in a sphere-packed bed has been extensively studied to simulate the cooling process of residual core fuel and fuel debris produced by a severe accident in a nuclear reactor. Recently, pore-network models were developed to consider local porosity structures in a packed bed. However, experimental data for further development of these models such as the three-dimensional void fraction distribution is insufficient. X-ray tomography is a powerful visualization tool that can be used to evaluate porosity and void fraction distributions. In this study, two-phase flow in a sphere-packed bed was investigated using X-ray tomography. The porosity and void fraction distributions were evaluated, and some characteristics of the two-phase flow in the near wall region and the center of the packed bed were discussed.