A drift-flux correlation for pool-type liquid metal two-phase flow based on fluid properties and flow characteristics

Accurately predicting the void fraction introduced into the core through the drift-flux correlation is fundamental for safety assessments of lead-cooled fast reactors under steam generator tube rupture scenarios. Due to the limitations of the applicability of existing drift-flux correlations for gas–water two-phase flow systems and the lack of experimental data, it becomes necessary to develop correlations suitable for gas–liquid metal two-phase flow through experimental studies. Flow measurements are conducted in a liquid metal pool using double-sensor conductivity probes to obtain local two-phase parameters. Results indicate radial profiles of parameters tend to evolve toward a core-peak shape with the increase in superficial gas velocity. The predictive performance of seven drift-flux correlations has been validated against the present data. No available correlations developed for gas–water two-phase flow systems can give accurate predictions for the present study. Although the correlations developed for gas–liquid metal two-phase flow systems provide good predictive performance, inaccuracies in predictions of the distribution parameter and drift velocity exist within the correlations. The study analyzes the effects of fluid properties and two-phase flow characteristics. A drift-flux correlation applicable to pool-type liquid metal two-phase flow is developed based on the limitations of existing correlations. The newly developed drift-flux correlation has been validated with the existing data, with the relative deviations in the void fraction predictions for the present data and other datasets being approximately less than ±15% and ±30%, respectively, and the corresponding mean absolute relative deviations are 5.35% and 18.19%, respectively.