Void fraction profile measurements in two-phase mercury-nitrogen liquid metal MHD power converter simulation system

To measure the void fraction profile in the upcomer of Liquid Metal Magnetohydrodynamic (LMMHD) system, a new method based on gamma ray attenuation is developed. Corrections due to various errors arising because of dynamic fluctuations in the flow, statistical fluctuation and curvature effect have been applied. The validity of this method has been verified by measuring the void fraction profile in a simulation system. Measurements were also carried out in nitrogen-mercury LMMHD system at the various location of the upcomer for different flow rates. The average void fraction calculated from the measured profile data has been verified with the empirical relation developed for two-phase upward flows. It is found that reliable void fraction profiles can be obtained in LMMHD two-phase flows, based on this method.