Two-phase wall and interfacial friction forces for annular flows in a 2x1 rods channel simplifying BWR

Most of recent subchannel analysis codes are based on a multi-fluid model, and accurate evaluation of the constitutive equations in the model is essential. In order to get accurate ones of the wall and the interfacial friction forces and validate them, experimental data on these forces have been obtained from the pressure drop and the void fraction data for air-water annular flows in 2x1 rods channel simplifying a BWR fuel rod bundle geometry. In order to know the effects of liquid properties on the data, water temperature was changed from 18 to 50degC. The wall and interfacial friction forces data determined are compared with the existing correlations reported in literatures. As a result, correlations of NASCA code and RELAP5/MOD2 code, and homogeneous flow model with McAdams's viscosity model for the wall friction force, and Fukano and Furukawa's correlation for the interfacial friction force show the best prediction against the present data. (author)