Experimental Study on Density Wave Instability of Sodium Boiling Two-Phase Flow in an Annulus

Experiments of density wave instability in a liquid sodium boiling two-phase flow experiments in an annulus were carried out in the following parameters range: heat flux from 80kW/m² to 976kW/m², inlet subcooling from 25.6°C to 226.8°C, mass flow rate from 7.92kg/h to 68.9kg/h, system pressure from 2600Pa to 0.12Mpa. Not only the mechanism of the instability, critical conditions and oscillation period, but also the effects of pressure, mass flow rate and inlet subcooling on the density wave instability were explored experimentally and theoretically. From the experimental data, it was found that the lower the inlet temperature was, the higher the system pressure and the mass flow rate that could result in a more stable boiling two-phase flow were. A correlation for the density wave instability was obtained on from the dimensional analysis for the conservation equations of mass, momentum and energy.