液滴碰撞液膜复合level set-VOF法的数值分析  

Numerical Analysis of a Coupled Level Set-VOF Method for the Study of Droplet Impact on Wetted Surface

作　　者：李大树[1,2] 仇性启[3] 郑志伟 张铎[4] 

机构地区：[1]中海油研究总院,北京100028 [2]中国石油大学(北京)博士后流动站,北京102249 [3]中国石油大学(华东)化学工程学院,山东青岛266580 [4]萨里大学工程与物理科学学院

出　　处：《高校化学工程学报》2017年第3期570-578,共9页Journal of Chemical Engineering of Chinese Universities

基　　金：国家高技术研究发展计划项目(2013AA092602);中央高校基本科研业务费专项资金项目(15CX06052A)

摘　　要：液滴碰撞液膜现象广泛存在于化工领域中。采用CLSVOF法建立了液滴碰撞液膜数值模型,并开展实验验证了模型的准确性。通过分析结果,研究了碰撞速度对液滴运动形态的影响,揭示了液滴内部流动传热和飞溅机理,并探索了液滴撞击液膜动力学和传热特性随碰撞速度的变化规律。研究表明:液滴碰撞液膜后随碰撞速度的增加依次呈现出波动、皇冠射流和射流飞溅等形态;碰撞速度越大,射流飞溅特征越明显。碰撞中心区域较大的压力梯度是液滴铺展的主要原因;铺展边缘较大气液压差是产生射流的主要原因;射流区域内速度间断是皇冠射流发展的关键因素;空气剪切及毛细波的作用是射流颈部收缩和产生飞溅的关键。碰撞速度越大,液滴的铺展系数、无量纲射流高度和壁面最大平均热流密度越大,无量纲液面中心相对高度越小;随着液滴雷诺数的增加,壁面最大平均热流密度的碰撞速度效应逐渐减小。Droplet impact on wetted surface is a widely existed phenomenon in spray control applications, while the mechanism of dynamic motion and heat transfer during impact is not well addressed. A numerical model was developed using a CLSVOF method and the model was validated by experiments. Effects of impacting velocity on droplet motion morphology, impacting dynamic and heat transfer were analyzed, and the mechanism of flow and heat transfer during impact was revealed. The results show that droplets present waving, crown jet and splash as impacting velocity increases. Splashing becomes more obvious when the impacting velocity increases. Pressure gradient inside droplets is the main factor that results in droplet spreading, liquid jet formation and splash. Shear action of surrounding air and capillary wave result in shrink, breakup and splash of the liquid sheet. Spreading factor, dimensionless jet height and maximum average wall heat flux increase with the increase of impacting velocity, while dimensionless height of central liquid surface decreases. Effects of impacting velocity on maximum average wall heat flux become less important as Reynolds number increases.

关 键 词：液滴碰撞液膜 铺展系数 动力学 传热 

分 类 号：TK01[动力工程及工程热物理] O359.1[理学—流体力学]