부산대학교 도서관

Experimental research on flow characteristics of open natural circulation system was performed, tofigure out the mechanism of the open natural circulation behaviors. The influence factors, such as theheating power, the inlet subcooled and the level of cooling tank on the flow characteristics of the systemwere examined. It was shown that within the scope of the experimental conditions, there are five flowtypes: single-phase stable flow, flash and geyser coexisting unstable flow, flash stable flow, flash unstableflow, and flash and boiling coexisting unstable flow. The geyser flow in flash and geyser coexisting unstable flow is different from classic geysers flow. The flow oscillation period and amplitude of the formerare more regular, is a newly discovered flow pattern. By drawing the flow instability boundary diagramand sorting out the flow types, it is found that the two-phase unstable flow is mainly characterized byboiling and flash, which determine the behavior of open natural circulation respectively or jointly. Moreover, compared with full liquid level system, non-full liquid level system is more prone to boilingphenomenon, and the range of heat flux density and undercooling degree corresponding to unstableflow is larger