Research on flow instability phenomena in FBR triple loop system

In the case of the plants which use high temperature working fluid and have free liquid surface, the variation of level and swirling of the liquid cause repeated thermal stress in vessels, and lead to the fatigue and breakdown of the vessels. In the case of the plants which have many free liquid surfaces in vessels, and those vessels are connected with pipings as a closed loop, in which working fluid circulates, liquid level causes the variation by the interference among free liquid surfaces. In the plants in which multiple loops are formed, which jointly own a part, the interference among respective loops occurs. In this research, regarding the triple loop system having many liquid surfaces, it was aimed at to examine the stability of free liquid surfaces. The testing setup comprises the main tank and three loops having one free liquid surface each, which are connected to the main tank. Water was circulated with a pump, and the variation of flow velocity in pipings and the variation of liquid level in the main tank were measured. Also the relation among the loops and the state of free liquid surfaces were examined by frequency analysis. The experimental setup, the water flow test and the experimental results are reported. The behavior of swirling became clear. (K.I.)