Experimental Research of flow instability onset conditions in a natural circulation system with subcooled boiling

With water as the working medium, this paper has investigated into the factors which affect the onset points of flow instability in the natural circulation system with subcooled boiling. Study finds that the increase of entrance subcoolling and pressure in the system can improve system stability. Increasing threshold heat flux can make the subcooling boundary area of density wave oscillation bigger. Both entrance subcooling and system pressure have significant influence on the position where ONB appears at stability boundary. According to dimensionless analysis of two-phase flow differential equations, this paper has put forward an semi-empirical formulae that can forecast the onset conditions of density wave oscillation.