方腔内石蜡固液相变及其非线性特性分析

Analysis of Solid-Liquid Phase Transition and Nonlinear Characteristics of Paraffin in Square Cavity

采用基于焓法的Solidification/Melting模型研究了固相区石蜡受热融化的相变特性以及液相区石蜡的流动特性。结果表明:在相同边界条件下方腔内石蜡融化出现多解现象,融化速率也不同;在液相区,底部石蜡液相区自然对流的流动状态受Ra影响;当Ra=3.5×10^(4)时相空间轨迹表现为一定点;当Ra=2.19×10^(5)时相空间轨迹表现为极限环;当Ra=2.3×10^(6)时相空间轨迹表现为混沌状;控制上下壁面温度恒定,通过改变模型的高度来改变Ra,可以控制液相区流场的最终状态。

Phase transformation characteristics of paraffin in solid phase and flow characteristics of paraffin in liquid phase were studied by using the Solidification/Melting model based on enthalpy method. Results show that under the same boundary conditions, the melting of paraffin in square cavity can be characterized by multiple solutions, and the melting rate is also different. In liquid phase region, the flow state of natural convection of paraffin heated at the bottom of square cavity is affected by Ra. When Ra=3.5×10^(4), the phase space trajectory is shown as a fixed point, which is shown as limit cycle and chaos at Ra of 2.19×10^(5) and 2.3×10^(6), respectively. Final state of the flow field in the liquid phase region can be controlled by setting the temperature of the upper and lower walls constant and changing Ra by controlling the height of the physical model.