铝合金超声波半连铸多场耦合的模拟与实验  

Simulation and Experimental Investigation of Multi-Field Coupling for Semi-Continuous Casting of Aluminum Alloy with Ultrasonic Treatment

作　　者：蒋日鹏[1] 李晓谦[1] 鞠增业[1] 张敏[1] 

机构地区：[1]中南大学机电工程学院∥高性能复杂制造国家重点实验室,湖南长沙410083

出　　处：《华南理工大学学报（自然科学版）》2014年第4期85-90,共6页Journal of South China University of Technology(Natural Science Edition)

基　　金：国家"973"计划项目(2010CB731706;2012CB619504);教育部博士研究生学术新人奖项目(103701007)

摘　　要：针对铝合金超声波半连铸过程,建立了声场、流场和温度场耦合的数学模型.利用Fluent模拟得到了声场、流场和温度场分布.仿真结果显示,超声波的导入对宏观流场与温度场分布具有重要影响,在超声输出振幅一定的条件下,选择频率为20kHz的超声波处理铝熔体能够获得较为理想的流场与温度场,从而有效促进熔体的传热、传质与柱状晶向等轴晶的转变.通过测量实验铸锭的晶粒尺寸,发现经超声处理的铸锭凝固组织显著细化,长度与宽度方向的平均晶粒尺寸分别较未经超声处理的减小了133μm与32μm.文中还结合数值模拟结果分析了超声波对铝合金大铸锭的细晶机理.In this paper,a mathematical model is established to describe the interaction and coupling of acoustic,flow and thermal fields in the semi-continuous casting of aluminum alloy with ultrasonic treatment （UST）,and the distribution of acoustic,flow and thermal fields is numerically simulated with Fluent.The results show that ultrasonic plays an important role in the distribution of flow and thermal fields ; and that,at a fixed ultrasonic output amplitude,a 20kHz UST for aluminum melt may result in ideal flow and thermal fields that speed up the heat and mass transfer as well as promote the transition of columnar grain to equiaxed grain.Moreover,it is found from microstructure test that,after the UST,the microstructure of casting ingot is well refined,and the average sizes of grains in length and width directions reduce by 133 μm and 32μm,respectively.The mechanism of grain refinement of large-scale aluminum alloy ingot caused by UST is finally analyzed based on the simulation results.

关 键 词：铝合金 半连铸 超声波 多场耦合 数值模拟 

分 类 号：TG249.7[金属学及工艺—铸造] TB559[理学—物理]