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利用高温熔体实时观察装置观察和研究了Bi12SiO20熔体中热毛细对流从稳态向振荡态的转变过程.稳态热毛细对流的模式由一个对流主干和两个分支组成.当振荡态对流引发后,对流主干的长度会随着温度的增加而增长.对流主干和分支是熔体表面变形的表现形式.在铂金环的两端施加了3种温度梯度:120,60和10K,铂金环上温度分布的变化直接导致了熔体热毛细对流方向的变化,从而引发了表面变形形式的改变.通过熔体温度分布的分析发现:表明表面变形总是形成于熔体内的低温区.表面变形的形成是熔体产生表面回流的主要原因.主干的振荡频率随着温度梯度的增加而增大.
The transition from steady state to oscillatory state of the thermocapillary convection in Bi12SiO20 melt was observed and studied by using a real-time high temperature melt device.The steady-state thermocapillary convection mode consisted of a convective trunk and two branches, , The length of the convective trunk increases with increasing temperature.The convective trunk and branches are the manifestations of the melt surface deformation.Three temperature gradients are applied at both ends of the platinum ring: 120, 60 and 10K, The change of the temperature distribution directly leads to the change of the convection direction of the melt capillary, which leads to the change of the surface deformation.The analysis of the melt temperature distribution shows that the surface deformation is always formed in the low temperature region of the melt. Is the main reason for the surface reflow of the melt.The main oscillation frequency increases with the temperature gradient.