The study on frictional resistance characteristics of narrow rectangular channel under rolling motion and highly subcooled boiling conditions

As a typical passive system, the natural circulation system is used in advanced nuclear power reactor systems because of its capability to enhance the inherent safety of nuclear power units. However, due to influenced by rolling motion, the thermal and hydraulic characteristics of such a system will change, affecting the operating characteristics of the system. In this paper, the experimental and numerical study was conducted on the frictional resistance characteristics of narrow rectangular channel in a natural circulation system under rolling motion and highly subcooled boiling conditions. The experiment result shows that the phase difference between flow rate and frictional pressure drop of narrow rectangular channel is approximately equal to zero. The revised calculated method of the frictional pressure drop, based on single-phase method, can applied to predict the frictional pressure drop of vertical narrow rectangular channel under highly subcooled boiling condition. Based on the comparison between experiment data and calculated value for frictional resistance of narrow rectangular channel, it can be concluded that the resistance correlations developed for steady state flow are feasible to predict the instantaneous frictional resistance for narrow rectangular channel under rolling motion and highly subcooled boiling conditions.