Numerical Prediction of Void Distribution in Two-Phase Turbulent Flow in a Subchannel

Numerical simulation code for predicting void distribution in two-phase turbulent flow in a subchannel was developed. The purpose is to obtain a profile of void distribution in the subchannel. The result will be used for predicting a heat flux at departure from nucleate boiling in a rod-bundle for the pressurized water reactor (PWR). The fundamental equations were represented by a generalized transport equation and the transport equation was transformed onto the generalized coordinate system fitted to the rod surface and the symmetric lines in the subchannel. Using the finite-volume method the transport equation was discretized for the SIMPLE algorithm. The flow field and void fraction at the steady-state were calculated for different average void fractions. The computational result for atmospheric pressure condition was successfully compared with experimental data. Sensitivity analysis for the PWR condition was performed, and the result showed that the secondary flow slightly contributed to homogenizing the void distribution.