水平管外高黏流体降膜流动形态及液膜分布规律的数值模拟  

Numerical simulation of the falling film flow pattern and liquid film distribution of high viscosity fluid outside horizontal tubes

作　　者：高祥 祝雪瑞 陈世昌[1,2] GAO Xiang;ZHU Xuerui;CHEN Shichang(National Engineering Lab for Textile Fiber Materials and Processing Technology,Zhejiang Sci-Tech University,Hangzhou 310018,China;Zhejiang Provincial Innovation Center of Advanced Textile Technology,Shaoxing 312030,China)

机构地区：[1]浙江理工大学纺织纤维材料与加工技术国家地方联合工程实验室,杭州310018 [2]浙江省现代纺织技术创新中心,浙江绍兴312030

出　　处：《浙江理工大学学报（自然科学版）》2023年第5期618-627,共10页Journal of Zhejiang Sci-Tech University(Natural Sciences)

基　　金：国家自然科学基金项目(52173047);浙江省重点研发计划项目(2021C01020)。

摘　　要：降膜元件上的流体流动行为能够反映该降膜式脱挥器的主要性能。采用数值模拟方法探究在水平管结构的降膜元件上高黏流体降膜流动的微观机理,在实验验证模型可靠性的基础上,考察不同流量下3层水平管外的高黏流体降膜流动形态及液膜厚度、速度变化规律等。结果表明:高黏流体在水平管外的降膜流动形态主要受重力和黏性力的影响,柱状流不易发展成完全的帘状流;高黏流体在水平管上部受到壁面支持力影响,而在水平管下部受到黏性力影响,流体会堆积在周向角0°~30°和150°~180°这两个区间内,导致液膜厚度异常增大;进液的3股流体在发生碰撞后,中间股液膜速度提高较多,但液膜厚度增加较少;流量减小至10.8 kg/h时,水平管外高黏流体会发生液膜收缩且内部出现空腔的现象,不利于高黏流体成膜流动。该研究可为水平管降膜式脱挥器的开发及工况设置提供参考。The flow behavior of fluid on the falling film element can reflect the main performance of the falling film devolatilizer.A numerical simulation method was proposed to explore the micro mechanism of the high viscosity fluid falling film flow on a falling film element of horizontal tube structure,and based on experimental verification of the model's reliability,the flow morphology,liquid film thickness,and liquid film velocity changes of high viscosity fluid falling film flow outside a three-layer horizontal tube under different flow rates were investigated.The results show that the falling film flow pattern of high viscosity fluid outside the horizontal tube is mainly influenced by gravity and viscous forces,and columnar flow is not easy to develop into a complete curtain flow;high viscosity fluid is affected by wall support force in the upper part of the horizontal tube,while it is affected by viscous force in the lower part of the horizontal tube.The fluid will accumulate in the circumferential angles in the range of 0°to 30°and 150°to 180°,resulting in an abnormal increase of liquid film thickness.After the collision of the three incoming fluids,the velocity of the middle liquid film increases more,but the thickness of the liquid film increases less.When the flow rate is reduced to 10.8 kg/h,the high viscous fluid outside horizontal tubes will experience liquid film contraction and internal cavity formation,which is not conducive to the film forming flow of the high viscous fluid.The research results can provide reference for the design and condition setting of new horizontal tube falling film devolatilizers.

关 键 词：水平管 高黏流体 降膜流动 液膜厚度 数值模拟 

分 类 号：TQ31[化学工程—高聚物工业]