Sub- to Supercritical Flow Transition in a Horizontally- Stratified Two-Phase Flow in PWR Hot Legs

抄録

A co-current, horizontally-stratified, two-phase flow would appear in the hot legs of a pressurized water reactor during a certain class of small-break loss-of-coolant accident. The liquid velocity in the hot leg may become so high that it exceeds the speed of interfacial waves. The condition for the onset of such a "supercritical" flow is studied in this paper by analyzing experimental data taken in the ROSA-IV Large Scale Test Facility. It is shown that the energy loss at the hot leg inlet needs to be taken into account to predict the above onset condition reasonably well.