本文通过匹配折射率和标定技术,应用PIV测量了圆柱腔体内水在底部冷却过程中热对流的变化规律.实验发现了主流场的涡结构;另外在底部拐角处出现新的涡,并且不断向上推移;冷却后期整个液相区出现流动反转现象,靠近壁面处水向上流动,中心区域水向下流动.因为存在着复杂的热交换和密度变化,水在凝固过程中存在流动结构失稳,使得液相区内发生强烈的热对流.最后流动强度减弱,重新形成稳定结构.结合泰勒不稳定性分析,本文对这一过程给出了合理解释.
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