Cross Flow Resistance in Air-Water Two-Phase Flow in Rod Bundle

摘要

In order to evaluate the cross flow rate during the reflood phase of a PWR-LOCA, a cross flow resistance of fuel rod bundle was experimentally obtained in an air-water two-phase flow in a rod bundle. The experimental ranges are: cross flow velocity at the gap between rods at the inlet and outlet sides of the bundle 0.224 - 2.99 m/s, vertical superficial water velocity 0.025 - 0.248 m/s, and void fraction 0 - 0.34. The air cross flow rate was small in comparison to the air up-flow rate. The cross flow resistance in the two-phase flow was much higher than that in a single-phase water flow. The cross flow resistance increased with the void fraction and decreased with the cross flow velocity up to a certain void fraction (critical void fraction). A correlation of the cross flow resistance was proposed for the void fraction range below the critical void fraction as a function of the void fraction and the cross flow Reynolds number. The critical void fraction increased with the cross flow and vertical water velocity. Above the critical void fraction, on the contrary, the cross flow resistance decreased with the void fraction. The cross flow attack angle against the bundle lattice had little effect on the two-phase cross flow resistance. (Atomindex citation 18:076926)