摘要
电磁冶金中氩气通常作为动力和载体将脱硫剂、脱氧剂吹入到液态金属中,因此存在磁场环境下气泡在液态金属中自由运动的问题,而绕流作为自由运动的特殊形态,是研究自由运动问题的第一步.本文通过有限元方法研究流向磁场作用下球形气泡绕流的全局线性稳定性,讨论基本流对时间-方位角模态小扰动的响应,发现了8个不稳定的驻定模态,并绘制它们在Re-Ha参数平面的中性曲线.结果显示方位角波数m=1的驻定模态首先导致第一次常规分岔,该模态已被广泛证实为轴对称绕流中最不稳定的模态,使轴对称尾迹转变为由一对反向旋转涡组成的单平面对称尾迹.同时第一次分岔的中性曲线展示磁场对球形气泡绕流先失稳后致稳的作用.后续分岔依次由定模态导致.这些分岔为认识磁场环境下气泡绕流的尾迹结构提供重要的参考价值.
In electromagnetic metallurgy,argon is usually used as a power and carrier to blow desulfurizer and deoxidizer into liquid metal,so there is a problem of free movement of bubbles in liquid metal under a magnetic field environment.Flow past a fixed bubble as a special form of free movement,is the first step to study the problem of free movement.In this paper,the global linear stability analysis of the flow past a spherical bubble under the effect of a streamwise magnetic field is simulated by the finite element method.The response of the steady axisymmetric basic flow to the small perturbation of the independent time-azimuthal mode in the range of Re≤1000,N≤60 is discussed.Eight unstable stationary modes are found,and their neutral curves in the Re−N parameter plane or Re−Ha parameter plane are displayed.The results show that the stationary mode with azimuthal wave number m=1 leads to the first regular bifurcation,this mode has been widely confirmed as the most unstable mode in the flow past axisymmetric objects,which transforms the axisymmetric wake into a plane symmetric wake composed of a pair of opposite vortices.In addition,the results of the neutral curve show the effect of the magnetic field on the instability of the flow past the spherical bubble.The subsequent bifurcations are successively caused by the unstable modes of m=2,3,...,8,these bifurcations provide an important reference value for understanding the wake structure of the flow past a bubble in the magnetic field environment.
作者
郑晓琳
潘君华
倪明玖
Zheng Xiaolin;Pan Junhua;Ni Mingjiu(School of Engineering Science,University of Chinese Academy of Science,Beijing 100049,China)
出处
《力学学报》
EI
CAS
CSCD
北大核心
2023年第7期1407-1416,共10页
Chinese Journal of Theoretical and Applied Mechanics
基金
国家自然科学基金(52006212)
中国科学院基础前沿科学研究计划(ZDBS-LY-JSC033)
中国科协青年人才托举工程(2022QNRC001)资助项目。
关键词
球形气泡绕流
线性稳定性分析
磁场
flow past a spherical bubble
linear stability analysis
magnetic field
