An Experimental Investigation on Characteristics of Liquid Film Thickness of Gas-Liquid Taylor Flow in Rectangular Microchannel

Liquid film thickness is one of the most important parameters for understanding two-phase flow in micro-scales. In the present work, experiments were conducted to investigate the variation of liquid film thickness in square tubes with hydraulic diameter Dh = 0.3, 0.5, 0.7, 1.0 mm, and rectangular tubes with a depth of 0.5mm and widths of 0.3, 0.5, 0.7, 1.0 mm. The liquid film thicknesses were measured using a laser focus displacement meter, and visualization images were captured by a high-speed camera. The experiments revealed that at low capillary numbers, surface tension determines the lower limit of the liquid film thickness in either square or rectangular microchannels. At medium capillary numbers, viscous force becomes prominent, and increase the thickness of the liquid film. At high capillary numbers, inertia forces determine the upper limit of the liquid film thickness. The non-uniform distribution of the liquid film thickness in rectangular channels intensifies with the increase in the aspect ratio of channel width to depth.