铝合金超声半连铸结晶器流场分析和试验研究  

Analysis of Flow Field in the Mould and Experiment Verification on Semi-continuous Casting Aluminum Alloy under Ultrasonic Treatment

作　　者：李晓谦[1] 赵世琏[1] 谢恩华[1] 陈铭[1] 李开晔[1] 

机构地区：[1]中南大学机电工程学院

出　　处：《特种铸造及有色合金》2010年第2期157-160,共4页Special Casting & Nonferrous Alloys

基　　金：国家高技术研究发展计划(863计划)资助项目(2005CB236707)

摘　　要：利用CFD商用软件FLUENT建立了7050铝合金超声半连铸圆坯结晶器的有限体积模型,运用动网格模型对超声作用下的结晶器流场进行分析,重点研究了超声声流现象对结晶器流场的影响。结果表明,在由于粘滞衰减产生声压梯度而形成的超声辐射力的作用下,熔体形成大规模的Eckart声流现象。由于声流速度幅值相比结晶器流场速度幅值和规模很小,因此其对结晶器流场无明显影响。在超声半连铸试验中,浇口流场所形成的涡流把超声工具杆端面下空化作用形成的等轴晶和有效形核质点转移到液穴的其他区域,并且把液穴内远离空化区的熔体带入工具杆空化区域形成新的形核质点,如此往复,在整个铸锭截面内都形成了等轴晶组织。声流场对于超声细晶区域的扩大作用很小,因此可以忽略不计。The FEM model of the mould for 7050 aluminum semi-continuous casting round billets was built up by CFD software Fluent, and flow filed of the aluminum alloy melts sonicated in the mould was analyzed, focusing on effects of acoustic streaming on the flow field. The results reveal that large-scale Echart acoustic streaming was formed in the liquid phase zone, driven by the radiation force which was formed as a result of the acoustic pressure gradient resulting from the viscous attenuation. As the amplitude and the scale of the Eckart acoustic streaming were much smaller than those of the flow field in the mould, effects of acoustic streaming on the flow filed can be neglected. The vortices from the flow field in nozzle transfer the effective nuclei and equiaxed grains formed in the cavitation area to the other area of the liquid pool and brings the other melt to the cavitation area in turn, forcing the others to be equiaxed grains and effective nuclei, finally, the structures of the ingot are all equiaxed grains. Effects of acoustic streaming on enlarging the refinement area can be negligible in the semi-continuous casting experiment.

关 键 词：半连铸 结晶器 超声波 流场 辐射力 声流 细晶区域 

分 类 号：TG27[金属学及工艺—铸造] TB559[理学—物理]