Numerical Simulation of Flow Field and Flow State Division in Thin-Film Evaporators  

薄膜蒸发器流场数值模拟及流态划分

作　　者：CHEN Xing PENG Yitian HUANG Yao ZOU Kun 陈星;彭倚天;黄瑶;邹鲲(东华大学机械工程学院,上海201620)

机构地区：[1]College of Mechanical Engineering,Donghua University,Shanghai 201620,China

出　　处：《Journal of Donghua University(English Edition)》2024年第5期525-535,共11页东华大学学报（英文版）

基　　金：National Natural Science Foundation of China(Nos.51905089 and 52075093);Special Fund for Basic Research and Operating Costs of Central Colleges and Universities,China(No.22320D-31);Open Fund for National Key Laboratory of Tribology of Tsinghua University,China(No.SKLTKF20B05)。

摘　　要：The flow field and flow state of thin-film evaporators are complex,and it is significant to effectively divide and quantify the flow field and flow state,as well as to study the internal flow field distribution and material mixing characteristics to improve the efficiency of thin-film evaporators.By using computational fluid dynamics(CFD)numerical simulation,the distribution pattern of the high-viscosity fluid flow field in the thin-film evaporators was obtained.It was found that the staggered interrupted blades could greatly promote material mixing and transportation,and impact the film formation of high-viscosity materials on the evaporator wall.Furthermore,a flow field state recognition method based on radial volume fraction statistics was proposed,and could quantitatively describe the internal flow field of thin-film evaporators.The method divides the high-viscosity materials in the thin-film evaporators into three flow states,the liquid film state,the exchange state and the liquid mass state.The three states of materials could be quantitatively described.The results show that the materials in the exchange state can connect the liquid film and the liquid mass,complete the material mixing and exchange,renew the liquid film,and maintain continuous and efficient liquid film evaporation.薄膜蒸发器的流场形态复杂,对内部的流场形态进行有效划分和定量分析以及探究内部的流场分布和物质混合特性对提升薄膜蒸发器效率意义重大。采用计算流体动力学(computational fluid dynamics,CFD)数值模拟,得到薄膜蒸发器内高黏度流体流场分布规律。研究发现交错打断叶片可以极大促进物质混合传输,并对蒸发器壁面高黏度物质成膜有显著影响。此外,提出了一种基于径向体积分数统计的流场状态识别方法,可以定量描述薄膜蒸发器的内部流场。该方法将薄膜蒸发器内的高黏度物质划分为液膜态、交换态和液团态三种流态的物质并做定量描述。结果表明,交换态物质可以连接液膜与液团,完成物质混合交换与液膜更新,维持液膜持续高效蒸发。

关 键 词：flow state division material mixing thin-film evaporator numerical simulation 

分 类 号：TS152[轻工技术与工程—纺织材料与纺织品设计] TH6[轻工技术与工程—纺织科学与工程]