Pressure drop characteristics on gas/liquid two-phase flow in a curved micro-channel affected by the wall wettability

A gas/liquid two-phase flow in a curved micro-channel is encountered in many application such as nuclear engineering, mechanical engineering, environmental engineering. In the present investigation, detailed observations on the flow patterns and measurements for pressure drop characteristics affected by the wall wettability were carried out. The test channel has square cross section that has 2.0 mm on a side, and the radii of the curvature were 1.0 mm and 3.0 mm. The superficial velocity of the gas and liquid are ranged from 0.083 m/s to 15.9 m/s for gas-phase, and 0.042 m/s to 1.67 m/s for liquid-phase, respectively. We could see the specific phenomena, the staying of bubbles and the changing of flow pattern near the exit of the curved part in the curvature radius 1.0 mm. Such as a polymer electrolyte fuel cell, there are curved micro-channels with the water repellent channel in practical use. So, in order to investigate the influence of the wall wettability, we applied the water repellent micro-channel. In the case of the water repellent micro-channel, we could see a new flow pattern of the rivulet flow. The pressure drop measurements were also carried out, we correlated the relation of the Lochhalt-Martinelli's parameter and the pressure fluctuation intensity. The pressure fluctuation became maximum value in the case of the slug-annular flow. (author)