摘要
磁场下的固-液相变过程在电磁冶金和增材制造等工程应用中广泛存在,其中的熔化过程和流动机理尚未完全探究清楚.方腔熔化是研究固-液相变过程的基础模型,具有良好的普适性,研究磁场对其流动的影响可以为其他复杂相变过程提供参考.本文基于焓方法开展了固-液相变的数值模拟研究,得到了垂直主环流方向的横向磁场对侧壁加热方腔中流动、传热和熔化过程的影响.首先,对于无磁场时的方腔熔化问题,通过与已有的实验结果和数值结果进行对比,证实了文献中方腔宽度对固-液界面的形状及位置影响不能忽视的结论.随后,对小磁场情况下的三维工况进行了直接数值模拟,发现此时磁场效应主要表现为对混乱三维流动产生整流作用,使流动趋于二维化.但由于固-液界面的存在,主流区的速度在趋于一致的同时也会反作用于界面,其形状随磁场增强而逐渐转变为二维结构.最后,本文采用准二维模型分析了更强磁场时的情形,讨论了不同参数对传热效率及界面形状的影响,并发现了横向磁场作用下的垂直最大速度仍满足磁对流中的无量纲参数标度律关系.
The solid-liquid phase change process in the presence of the magnetic field has extensive and important applications in industrial engineering,i.e.the electromagnetic metallurgy and additive manufacturing,where the melting process and flow mechanisms have not been fully explored.The cavity melting model,as a basic problem,has good universality to study the solid-liquid phase change process,and it can also provide some basic information for the magnetohydrodynamics influence on the phase change problems.In this paper,the solid-liquid phase change process is simulated based on the enthalpy method,and the physical model of the cavity heated from the left wall is considered,with a transverse magnetic field perpendicular to the main circulation direction.The flow field,heat transfer and melting processes are investigated,focusing to the influences of different factors.At first,for the melting problem of a square cavity without a magnetic field,we compared our numerical solution with the experimental results reported by some other literatures,and it is confirmed that the influence of the cavity width on the profile and position of the solid-liquid interface cannot be ignored.Subsequently,we use the 3 D model to simulate the cases in the presence of small magnetic fields,and it is found that the Lorentz force mainly acts as a rectification effect on the chaotic 3 D flow,making the flow tend to be quasi-2 D(Q2 D).Meanwhile owing to the existence of the solid-liquid interface,the velocity field in the mainstream region tends to be more uniform under the external magnetic field,and thus the shape of the solid-liquid interface also transforms into the 2 D structure correspondingly.Finally,the Q2 D model is used to study the cases under greater magnetic fields,and the influences of different parameters on the heat transfer efficiency and interface shapes are discussed.Moreover,the scaling law to describe the relation between the max vertical velocity and other dimensionless parameters is also proposed,in order to quantitatively characterize the melting process under the transverse magnetic field.
作者
孙思睿
张杰
倪明玖
Sun Sirui;Zhang Jie;Ni Mingjiu(School of Engineering Science,University of Chinese Academy and Sciences,Beijing 100049,China;State Key Laboratory for Strength and Vibration of Mechanical Structures,School of Aerospace,Xi'an Jiaotong University,Xi'an 710049,China)
出处
《力学学报》
EI
CAS
CSCD
北大核心
2022年第9期2377-2386,共10页
Chinese Journal of Theoretical and Applied Mechanics
基金
国家自然科学基金(11872296,51927812)资助项目。
关键词
固-液相变
磁流体
焓方法
数值模拟
solid-liquid phase change
magnetohydrodynamics
enthalpy method
numerical simulations
