高Prandtl数双层流体的热毛细对流数值模拟  

Numerical Simulation of Thermocapillary Convection of High Prandtl Number Fluid in Two-layer System

作　　者：莫东鸣[1] MO Dongming(Department of Mechanical Engineering and Automation,Chongqing Industry Polytechnic College,Chongqing 401120,China)

机构地区：[1]重庆工业职业技术学院机械工程与自动化学院,重庆401120

出　　处：《材料导报》2021年第S01期302-305,共4页Materials Reports

基　　金：重庆市基础研究与前沿探索专项项目(cstc2018jcyjAX0597);重庆市教委科学技术研究项目(KJQN201803201);重庆市高校创新研究群体项目:晶体生长及其制备。

摘　　要：不相溶混的双层流体系统的传热传质现象广泛地存在于自然界和工程技术领域中,尤其是芯片工业与微电子工业中半导体材料的液封提拉法生长制备工艺中,双层流体的流动稳定性直接影响着晶体材料的生长质量。微重力条件下,由于没有了重力的影响,可以增强双层流体流动的稳定性以获得更为优异的晶体生长环境,然而,两相界面处的热毛细力引起的热毛细对流却对双层流体系统中的传热传质现象影响甚大。目前,可采用实验研究的方法对水平温度梯度作用下的双层流体的热毛细对流进行可视化研究,以观测流动特性及失稳的耗散结构。在空间实验中,由于低Prandtl数流体不可透视的特性,故在实验中鲜少采用其作为观察工质,多采用高Prandtl数流体。关于双层流体的热毛细对流,前人的研究主要集中在矩形腔体内环形池内的低Prandtl数双层流体的流动特性,对环形液池中高Prandtl数双层流体的流动特性及失稳耗散结构的研究还鲜见报道。本工作针对微重力条件下,水平温度梯度作用下的环形液池内B_(2)O_(3)/蓝宝石熔体、5cSt硅油/HT-70、水/FC-75三组工质对的热毛细对流特性进行了研究,采用数值模拟的方法获得了R-Z截面的流函数、温度分布,以及监测点的速度和温度周期波动,揭示了流动失稳后的振荡流型。研究结果表明,运动粘度会影响流动流型,对于运动粘度较低的5cSt硅油/HT-70、水/FC-75的工质对,流动失稳为热毛细对流失稳,而高运动粘度的B_(2)O_(3)/蓝宝石熔体则出现了热毛细对流失稳与Marangoni失稳。对比三种工质对的流动失稳临界Marangoni数,发现上下液层Prandtl数比值越大,则临界Marangoni数越大,选择较大的上下液层Prandtl数比值,可增强环形双液层流体流动稳定性。The phenomenon of heat and mass transfer in immiscible two-layer fluid system widely exists in nature and engineering technology.Especially in the liquid sealed Czochralski growth process of semiconductor materials in chip industry and microelectronics industry,the flow stability of double-layer fluid directly affects the growth quality of crystal materials.In microgravity,the stability of the two-layer fluid flow can be enhanced to obtain a better crystal growth environment without the influence of gravity.However,the thermocapillary convection caused by the thermocapillary force at the two-phase interface has a great influence on the heat and mass transfer in the two-layer fluid system.At present,experimental me-thods can be used to visualize the thermocapillary convection of two-layer fluid under horizontal temperature gradient to observe the flow characteristics and unstable dissipation structure.In space experiments,due to the non perspective property of low Prandtl number fluid,it is seldom used as the observation working fluid,but high Prandtl number fluid is used.As for the thermocapillary convection of two-layer fluid,previous stu-dies mainly focused on the flow characteristics of low Prandtl number two-layer fluid in an annular pool in a rectangular cavity,while the study on the flow characteristics and unstable dissipation structure of high Prandtl number two-layer fluid in an annular pool is rarely reported.In this paper,the thermocapillary convection characteristics of B_(2)O_(3)/sapphire melt,5cSt silicone oil/HT-70 and water/FC-75 working pairs in an annular liquid pool under microgravity and horizontal temperature gradient were studied.The flow function and temperature distribution of R-Z section,as well as the periodic fluctuation of velocity and temperature at monitoring points were obtained by numerical simulation.The oscillating flow pattern after flow instability was revealed.The results show that the kinematic viscosity can affect the flow pattern.For the working pair of 5cSt silicone oil/HT

关 键 词：高Prandtl数流体 双液层 热毛细对流 数值模拟 流动稳定性 

分 类 号：O647[理学—物理化学]