Effect of rolling motion on two-phase frictional pressure drop of boiling flows in a rectangular narrow channel

In order to investigate the two-phase frictional pressure drop characteristics of boiling flow in a rectangular narrow channel under rolling motion, a series of experiments and theoretical analysis are performed. The results demonstrate that the total additional pressure drop fluctuation has the same period with the rolling motion, and the fluctuation amplitude increases with the increase of rolling amplitude and rolling frequency. The time average additional pressure drop is 2-3 orders of magnitude smaller than that of frictional pressure drop in the boiling region. The fluctuation amplitude of the two-phase frictional pressure drop increases with increasing rolling amplitude, rolling period and heat flux, while it decreases with the increase of system pressure. Compared with the additional pressure drop in two-phase regions the outlet quality of channel and the space variation of the experimental loop are the main reasons that induce the fluctuation of two-phase frictional pressure drop. The mass flux fluctuation varies with the fluctuation of two-phase frictional pressure drop, and the fluctuation amplitude of mass flux increases with the increase of rolling amplitude and rolling period. The phase lag between the fluctuation of mass flux and frictional pressure drop is approximately equal to 1/4 rolling period.