Gas-liquid Interfacial Friction Factor under Flooding Conditions in Vertical Pipes

Abstract

In our previous studies, we carried out air-water counter-current flow experiments under flooding conditions in vertical pipes of 40 mm diameter with combinations of sharp-edged or rounded top and bottom ends to measure counter-current flow limitation (CCFL), pressure gradient dP/dz, and void fraction α_G. We obtained the wall and interfacial friction factors, f_w and f_i, and proposed a correlation of f_w. In the present study, we carried out similar experiments with sharp-edged top and bottom ends, and obtained f_w and f_i. We proposed a correlation of f_i for all flow patterns including smooth film (SF) and rough film (RF) due to flooding at the top and bottom ends, respectively. By using the one-dimensional annular flow model and the proposed f_w and f_i correlations, we computed the liquid volume fraction α_L,cal and compared it with the experimental data α_L,exp. The computation gave two solutions of α_L,cal for SF and RF, which agreed relatively well with the α_L,exp values for SF and RF in the regions of low gas superficial velocity J_G and high J_G, respectively.