单液滴撞击冷板面的实验和模拟

用实验和模拟的方法研究了直径为3.2 mm的单个蒸馏水液滴与冷板面（温度低于273 K）撞击铺展和固化过程，分析了撞击高度（100、250、500 mm）、板面温度（253、268 K）、板面倾角（0°、30°和60°）对撞击过程的影响以及液滴在冷板面上冻结过程。并模拟了单个普鲁兰多糖溶液液滴在撞击高度为100 mm、板面温度为253 K的过程。结果表明，撞击高度与板面温度对液滴在水平冷板面的铺展过程起到重要作用，板面倾角会影响液滴撞击倾斜板面时的冷冻沉积。物料的黏度会影响液滴冷冻沉积时的铺展速率及铺展直径，而对于较高黏度物料，温度并不起决定作用。模拟和实验结果吻合较好，反映了液滴铺展冻结过程中的温度变化，有利于直观解释液滴发生冻结的状况。

Experiments and simulation of a single droplet impacting on cold surfaces

The impact spread and solidification of single distilled water droplet of 3.2 mm in diameter at 293 K on a cold plate with temperature below 273 K was studied by both experiment and simulation. The impact heights (100, 250, 500 mm), cold plate temperatures (253, 268 K), and cold plate inclined angles (0°, 30° and 60°) were assessed for effects on the spreading and solidifying process. The impact process of a pullulan solution droplet at a height of 100 mm on a cold plate at 253 K was simulated and compared to that of a distilled water droplet. The results showed that both impact height and horizontal cold plate temperature played an important role in the droplet spreading process whereas inclined angle of cold plate affected freezing deposition of the droplet. Droplet viscosity affected spreading rate and diameter of freezing deposition. Temperature was not a determinant factor for highly viscose materials. A good alignment between simulation and experimental results indicated that temperature change of the droplet in spreading and freezing process would help to directly explain droplet solidification.