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|Issue Date: ||2014-10-15 17:20:22 (UTC+8)|
;This research presents the modified capillary number for determining the fingering instability in radial flow. Experiments were conducted using the silicon oil and air pushing each other in the two dimensional Hele-Shaw porous media of different pore sizes. Two kinds of zirconia particles with different average diameters of 1 mm and 0.1 mm respectively were used to form different pore sizes. The processes of flow were recorded by a CCD camera and the pressures of the pushing fluid were monitored by installing a pressure sensor at the fluid inlet for different particle sizes and injection rates.
Results showed that three flow regimes could be identified from the experiments: stable displacement, capillary finger and viscous finger. In the case of silicon oil (large viscosity) pushing air (small viscosity), silicon oil was continuously moving towards the outlet. The silicon oil and the air maintained a stable and smooth interface during the entire flow course at different injection rates and pore sizes. Oppositely when air (small viscosity) was used to push silicon oil (large viscosity), two flow types were observed, which could be referred to as the capillary fingering and the viscous fingering flows. The capillary fingers dominated by the capillary pressure transited into the viscous fingers dominated by the viscous force as the modified capillary numbers were increased. The small pore size corresponded to a higher modified capillary number in the same injection rates, so the fingering transition occurred more easily for the small pore size than the big one.
|Appears in Collections:||[機械工程研究所] 博碩士論文|
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