Distribution parameter and drift velocity for upward gas-liquid metal two-phase flow

In view of the needs in the developments of the fast-neutron nuclear reactor, the accelerator driven nuclear reactor system, the fusion reactor and so on, this study has conducted an extensive literature survey on the past experimental and theoretical studies of the upwardly-moving gas-liquid metal two-phase flows in the vertical flow channels with various channel geometries. The experimental data of the upward gas-liquid metal two-phase flows taken in the N-2-Hg (nitrogen and mercury), N-2-Pb/Bi (nitrogen and lead/bismuth eutectic alloy), N-2-Ga (nitrogen and gallium) and N-2-Na/K(nitrogen and sodium/potassium eutectic alloy) mixtures in the vertical circular, annular and rectangular flow channels and seven available drift-flux type correlations used for the void fraction predictions in the gas-liquid metal two-phase flows have been collected. The performances of these seven drift-flux type correlations have been checked against the collected experimental data, and no available drift-flux type correlation is able to predict well the void fraction of the gas-liquid metal two-phase flows with low gas-to-liquid density ratios. So, this study has analyzed the effects of the two-phase density ratio, the flow channel size and shape, the local two-phase flow conditions and the wettability between the liquid metal and the flow channel wall surface on the two-phase flow behaviors and has proposed general mathematical expressions for the distribution parameter and the drift velocity. By fitting the experimental data, a new constitutive correlation for the distribution parameter and the drift velocity consisting of two flow-regime-independent correlation sets, which are, respectively, for the gas-liquid metal two-phase flows with the low and high wettability between the liquid metal and the flow channel wall surface, has been developed. The newly-developed drift-flux type correlation has been evaluated with the collected experimental data of the gas-liquid metal two-phase flows, and their mean relative error is 0.109. The predicted mean relative errors of the low and high wettability drift-flux type correlation sets are, respectively, 0.132 and 0.0782 for the gas-liquid metal two-phase flows with the low and high wettability between the liquid metal and the flow channel wall surface.