液层Pr比值对环形双液层热毛细对流的影响

Effect of Ratio between upper and lower liquid layers Prandtl number on thermocapillary convection in annular two-layer-layer

中文关键词: 热毛细对流  特朗普数  线性稳定性分析  双液层

英文关键词: thermocapillary convection  Prandtl number  linear stability analysis  two liquid layers

中文摘要:

      为了解双层流体系统上液层流体与下液层流体特朗普数（Pr）对热毛细对流的影响，通过线性稳定性分析，确定了上液层流体与下液层流体Pr数比值从0.164-5.417范围内环形双层流体热毛细对流失稳的临界条件，预测了它们的4种流动失稳型式，即轮辐状的几乎占据了整个液层的“轮辐波”、轮辐状的热流体波与同波数共同旋向的靠热壁处流胞、径向流动的三维稳态流动、靠热壁处的短小的“边沿波”。结果发现：随着上、下液层Pr比值的增大，环形双液层流体的流动稳定性以上、下液层Pr比值0.750为分界线呈分段上升趋势。上、下液层Pr比值约为0.750时，双液层流体的稳定性最差，此时易出现流动分岔现象。为了获得更好的系统流动稳定性、提高生长晶体的质量，在选择双液层工质对时，应选择上、下液层Pr比值较大的工质对。

英文摘要:

      In order to understand the influence of Prandtl number (Pr) of upper and lower liquid layer fluids on the thermocapillary convection in a two-layer fluid system, the critical conditions of the ratio of Pr number of upper and lower liquid layer fluids from 0.164 to 5.417 were determined, and four types of flow instability were predicted by linear stability analysis. The four types of flow instability are: a wide spoke-like perturbation patterns, occupying the whole liquid layer, called as“spoke patterns”; the spoke-like hydrothermal wave and flow cells near the hot wall with the same wave number rotating together; the radial flowing three dimensional steady flow; the short “edge wave” near the hot wall. The results show that the flow stability of annular double liquid-layer fluid increases with the increase of Pr ratio in the upper and a lower liquid layer, by stages segregated with Pr is 0.750. When the Pr ratio is about 0.750, the stability of the two liquid layer is the worst, and the flow bifurcation phenomenon is easy to occur. In order to obtain better system flow stability and improve the quality of crystal growth, the working pair with higher Pr ratio in upper and lower liquid layers should be selected when selecting two liquid layer working pairs.