Subcooled boiling flow exists in many technical applications of process and engineering such as nuclear reactors

steam generators and refrigeration systems. Accurate prediction of local void fraction is of significance for establishment of two-phase flow mathematical model and estimation of pressure loss and heat transfer capability. The radial local void distribution of subcooled boiling flow under rolling conditions was experimentally investigated by double-sensor optical probe

of which the transient local void fraction was obtained by periodical accumulation method. It showed that the local void distribution under rolling conditions exhibited a periodic variation

where the peak void fraction appeared in near-core region and near-wall region of the circular tube

and the largest amplitude of local void fluctuation existed in the near-wall region. Different from that under static conditions

the spatial distribution of local void fraction changed with the time within a rolling period. Furthermore

the period and amplitude rolling influence the distribution of local void fraction.