612 圧力振動脱泡における流体の弾性効果に関する実験的研究(2)(OS6-3 非ニュートン流体の流動現象,OS6 非ニュートン流体の流動現象,オーガナイズドセッション)

概要

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An experimental measurement of local flow velocity profile around a small bubble under pressure-oscillatory field obtained by a visualization technique is presented; that is used to estimate an enhancement in defoaming performance of the fluids. This measurement requires velocity data of pigment particles distributed around the bubble as well as the bubble diameter over a cyclic period; those enable us to measure the velocity gradient directly. A high density video camera with a help of strobe scope lighting was used to record the vibrating bubble, because the applied oscillation frequency was more than a frame speed of the commercial video camera. It was found that observed radial velocities were not the same along the bubble surface; the velocities in the upper region were smaller than the lower region, because fluid in upper region was surrounded by the rigid cell wall and fluid pressed from the downside. Shear rates at lower and side bubble surface, estimated by velocity profile of the distributed pigments, agreed well with one estimated by the simple sphere model using time series data of observed bubble diameter. In addition, the fluid was measured by the cone-plate viscometer.
一般社団法人日本機械学会の論文
2007-11-17