抄録
Experimental study was made on the multidimensional behavior of upward gas-liquid two-phase flow in a vertical pipe with an axisymmetric sudden expansion, which is one of the typical multi- dimensional channel geometries. In this report, the void fraction distributions along the flow direction at the below and above of the sudden expansion were measured for various flow conditions. Based on the void fraction distributions, the cross-sectional averaged void fractions were calculated for various locations in the flow direction. The detailed void fraction data was compared with the flow patterns in the sudden expansion. Furthermore, the prediction of averaged void fraction in the flow direction was carried out using one-dimensional two-fluid model (see Fig. 1). We have discussed whether such void fraction distributions in the sudden expansion can be predicted or not by analytical results. As results, it concretely pointed out that some multi-dimensional modeling or modifications for numerical simulation would be needed for more accurate prediction of two-phase flow. However, they also revealed that the two-phase flow behavior even in the sudden expansion might be predicted to a certain extent using the one-dimensional two-fluid model. if the values of C_O and V_<gi> could be successful and accurately obtained on the basis of experimental data (see Fig. 2).
