Frictional resistance of adiabatic two-phase flow in narrow rectangular duct under rolling conditions

Frictional resistance of air-water two-phase flow in a narrow rectangular duct subjected to rolling motion was investigated experimentally. Time-averaged and transient frictional pressure drop under rolling condition were compared with conventional correlation in laminar flow region (Rel < 800), transition flow region (800 ⩽ Rel ⩽ 1400) and turbulent flow region (Rel > 1400) respectively. The result shows that, despite no influence on time-averaged frictional resistance, rolling motion does induce periodical fluctuation of the pressure drop in laminar and transition flow regions. Transient frictional pressure drop fluctuates synchronously with the rolling motion both in laminar and in transition flow region, while it is nearly invariable in turbulent flow region. The fluctuation amplitude of the Relative frictional pressure gradient decreases with the increasing of the superficial velocities. Lee and Lee (2002) correlation and Chisholm (1967) correlation could satisfactorily predict time-averaged frictional pressure drop under rolling conditions, whereas poorly predict the transient frictional pressure drop when it fluctuates periodically. A new correlation with better accuracy for predicting the transient frictional pressure drop in rolling motion is achieved by modifying the Chisholm (1967) correlation on the basis of analyzing the present experimental results with a great number of data points.

► Two-phase flow frictional resistance in narrow duct in rolling is studied.
► Frictional resistance behaviors in rolling are divided into three regions.
► Transient frictional pressure drop fluctuates synchronously with rolling motion.
► Conventional correlations are evaluated against experimental data in rolling motion.
► New correlation for transient frictional resistance in rolling motion is developed.