Materials Reports  2021, Vol. 35 Issue (Z1): 302-305 |
| INORGANIC MATERIALS AND CERAMIC MATRIX COMPOSITES |
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| Numerical Simulation of Thermocapillary Convection of High Prandtl Number Fluid in Two-layer System |
| MO Dongming
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| Department of Mechanical Engineering and Automation, Chongqing Industry Polytechnic College, Chongqing 401120, China |
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Abstract 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 B2O3/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-70 and water/FC-75 with low kinematic viscosity, the flow instability is thermocapillary convection instability, while for the B2O3/sapphire melt with high kinematic viscosity, thermocapillary convection instability and Marangoni instability appear. By comparing the critical Marangoni number of the three working pairs, it is found that the larger the Prandtl number ratio of the upper and lower liquid layers is, the larger the critical Marangoni number is.
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Published: 16 July 2021
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| Fund:Chongqing Research Program of Basic Research and Frontier Technology (cstc2018jcyjAX0597), Science and Techno-logy Research Program of Chongqing Municipal Education Commission of China (KJQN201803201) and Innovative Research Group Project of Colleges and Universities in Chongqing: Crystal Growth and Preparation. |
| About author:: Dongming Mo received her Ph.D. from the College of Power Engineering, Chongqing University, in 2012. In 2014, she won the title of Chongqing Young Backbone Teacher. She worked as a postdoctoral fellow during July 2016—Setemper 2019 in postdoctoral station of mecha-nical engineering, Chongqing University, and is currently an associate professor in department of mechanical engineering, Chongqing Industry Polytechnic College. Her major area is stability analysis of thermocapillary flow. As the first author, she has published more than 20 papers in domestic and foreign academic journals, published one monograph, and obtained 7 utility model patents. She presided over 5 provincial and ministerial level projects such as Chongqing Natural Science Foundation and science and technology research projects of Chongqing Municipal Education Commission, participated in 2 general projects of National Natural Science Foundation of China and innovative research projects of Chongqing universities. |
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