Two-phase frictional pressure drop and water film thickness in a thin hydrophilic microchannel

This study focuses on the experimental investigation of the two-phase pressure drop and water film thickness in a thin microchannel. Air-water flow in the thin channel of dimensions 3.23 mm wide by 0.304 mm high produces a stratified flow over a range of test conditions. The experimental data allowed for the assessment of several models including homogeneous, separated, and relative permeability models. A comparison of the two-phase pressure to the recently developed two-fluid model (Wang, 2009) resulted in a new exponent (nk) of 1.159 for the relative permeability, which produced a mean absolute percent error of 3.25%. Imaging of the air-water flow allowed for measuring the water film thickness, which showed good agreement with the analytical solution of Steinbrenner (2011) and the two-fluid model with a mean error of −0.035. The study demonstrates the applicability for the two-fluid model to predict both the two-phase pressure and the water film thickness in thin microchannels.