Calculation of two-phase flow redistribution due to void drift between subchannels by a two-fluid model. Examination of constitutive equations for wall and interfacial frictions

A subchannel analysis code based on a two-fluid model has been proposed and used to calculate two-phase gas-liquid flow redistribution due to void drift between subchannels. In the code, Lahey et al.'s void settling model was incorporated with usual conservation equations of mass and momentum. And then, in order to refine the code, constitutive equations of wall friction, FW, and interfacial friction, FI, needed in the two-fluid model were examined against the redistribution data in our previous experiments. From the examination, it was proved that the FW should be calculated from a separated flow model, and FI from a correlation depending upon the void fraction, α: Tomiyama et al.'s correlation for 0.4 < α < 0.7, interpolation equation with Tomiyama et al.'s and Fukano and Furukawa's correlations for 0.7 < α < 0.8, Fukano α Furukawa's correlation for 0.8 < α < 0.9, and Wallis' correlation incorporated with liquid entrainment effects in the gas core in annular flow for α > 0.9. (author)