ACRT过程Ekman流场的实验研究  

EXPERIMENTAL STUDY OF THE ACRT EKMAN FLOW

作　　者：刘俊诚[1] 介万奇[1] 周尧和[1] 

机构地区：[1]西北工业大学凝固技术国家重点实验室

出　　处：《金属学报》1996年第3期269-273,共5页Acta Metallurgica Sinica

基　　金：国家自然科学基金

摘　　要：利用水模拟实验，研究了ＡＣＲＴ（坩埚加速旋转技术）过程中Ｅｋｍａｎ流场的稳定性，及其与坩埚内径Φ，转速最大差值△ωｍａｘ，及坩埚中液体高度Ｈ的关系。结果表明，当雷诺数Ｒｅ＝０．６７８Ｒ（｜△ωｍａｘ｜／ｖ）０．５≤ＲｅＣｌ（下临界值）时，Ｅｋｍａｎ流场稳定；Ｒｅ≥ＲｅＣ２（上临界值）时，减速过程的Ｅｋｍａｎ流场完全不稳定。当Ｒｅ≤ＲｅＣｌ时，Ｅｋｍａｎ流区的高度ｈ随Φ及△ωｍａｘ增加而增加，Ｅｋｍａｎ流区相对高度ｈ／Ｒ（Ｒ＝０．５Φ）与Ｒｅ２呈线性关系，直线的斜率ｋ与Ｒ有关；当坩埚中液柱高度Ｈ减小到某一临界值Ｈ时，Ｅｋｍａｎ流区随Ｈ的减小而减小。The stability of the Ekman flow during ACRT (accelerated crucible rotation technique) process, and the effects of the crucible diameter Φ, the maximum variation of the rotation speed, △ωmax , as well as the liquid height H in the crucible on the Ekman flow,were studied with hydraulic analogue experiments. The result shows that, if Reynolds number Re ≤ ReC1(the low critical Re), the Ekman flow is stable, if Re≥ ReC2(the high critical Re), the Ekman flow during the crucible deceleration period is unstable, and the Ekman flow height h increases with increase of the crucible diameter Φ and the maximum variation of the rotation speed △ωmax . When Re≤ ReC1, the relation between the ratio h / R (R = 0.5Φ) and Re2 is linear. When the liquid height H< H(a critical value), the Ekman flow height h decreases with decrease in the liquid height H.

关 键 词：坩埚加速旋转 对流 流场 Ekman流场 

分 类 号：TK124[动力工程及工程热物理—工程热物理]