Numerical modelling of metal droplet cooling and solidification
Numerical modelling of metal droplet cooling and solidification
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DOI：
10.1016/j.ijheatmasstransfer.2007.11.044
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发表时间：
2008-07
影响因子：
5.2
通讯作者：
N. Zeoli;S. Gu;S. Kamnis
中科院分区：
文献类型：
--
作者：
N. Zeoli;S. Gu;S. Kamnis
在电力生产的雾化过程中，金属液滴在完全凝固之前经历过冷、再辉、包晶和分离凝固。由于雾化过程中液滴的破碎，冷却过程进一步复杂化。本文描述了一种在一次计算中同时考虑冷却和破裂的数值模型。在欧拉气体流动中，液滴的动态历史被求解为离散相。液滴和气体流动之间的耦合是双向的，其中影响气体流动的热量和动量交换在流体方程中被视为源/汇项。将液滴模型应用于金属粉末生产的气体雾化过程，得到了与公开文献相一致的结果。模型结果进一步证实了颗粒的热历史强烈依赖于初始液滴尺寸。大液滴不会经历过冷，而小液滴有可识别的过冷、不透明和复燃阶段。结果表明，雾化过程中雾化液滴的形状非常相似，影响雾化和凝固过程的主要因素是飞行距离。
In an atomisation process for power production, metal droplets go through undercooling, recalescence, peritectic and segregated solidification before fully solidified. The cooling process is further complicated by droplet break-up during the atomisation. This paper describes a numerical model which combines both cooling and break-up in a single computation. The dynamic history of droplets is solved as discrete phase in an Eulerian gas flow. The coupling between droplet and gas flows are two-way, in which the heat and momentum exchanges affecting the gas flow are treated as source/sink terms in the fluid equations. The droplet model is employed to a gas atomisation process for metal powder production and good agreement is achieved with the results in open literature. The model results further confirm that thermal history of particles is strongly dependent on initial droplet size. Large droplets will not go through undercooling while small droplets have identifiable stages of undercooling, unclearation and recalescence. The predictions demonstrate that droplets have very similar profiles during gas atomization and the major factor influencing the atomization and solidification process of droplets are in-flight distance.