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使用Bridgman单向冷冻实验对毫米量级刚性颗粒与界面的相互作用进行可视化研究,观察到低速冷冻、中速冷冻、高速冷冻下三种不同现象.经典润滑理论指出,颗粒与界面之间总是存在极小的间隙.颗粒被推挤时,周围流体会流入到此间隙中,以供应相变过程中的界面成长.低速冷冻时界面首先要克服底面摩擦力才能推动颗粒;中速冷冻时颗粒周围的水有足够的时间补充到颗粒与界面的间隙中,颗粒可被界面持续推挤;高速冷冻时此间隙来不及补充液体,颗粒被界面包陷.低、中速冷冻时,界面呈直线;高速冷冻时,界面出现大量针状冰晶,界面表现出在液体底表和上表面不同步的斜面,差异宽度会随冷冻速度降低而减小.
The Bridgman one-way freezing experiment was used to visualize the interaction between the millimeter-sized rigid particles and the interface, and three different phenomena were observed under low-speed, medium-speed and high-speed freezing.Classical lubrication theory states that the interaction between particles and interface is always There is a very small gap.When the particles are pushed, the surrounding fluid will flow into the gap, in order to supply the interface during the phase change growth.Firstly, the interface of the low speed freezing must overcome the friction of the bottom to push the particles; The surrounding water has sufficient time to replenish the gap between the particles and the interface, and the particles can be continuously pushed by the interface; when the high-speed freezing is insufficient, the gap is not enough to replenish the liquid and the particles are trapped by the interface; When frozen at high speed, a large number of acicular ice crystals appeared on the interface. The interface showed a slant on the bottom surface and the upper surface of the liquid, and the difference width decreased as the freezing speed decreased.