超声波熔体处理过程中的声流现象  

Acoustic streaming phenomenon during ultrasonic sonication on melt

作　　者：谢恩华[1] 李晓谦[1] 

机构地区：[1]中南大学机电工程学院现代复杂装备设计与极端制造教育部重点实验室,长沙410083

出　　处：《北京科技大学学报》2009年第11期1425-1429,共5页Journal of University of Science and Technology Beijing

基　　金：国家重点基础研究发展计划资助项目(No.2005CB23707)

摘　　要：应用CFD软件Fluent对坩埚中进行超声处理的铝合金熔体流场进行模拟计算.计算结果表明,在由于黏滞衰减产生声压梯度而形成的超声辐射力的作用下,工具杆端面下液相区域内的熔体形成大规模的Eckart声流现象,熔体的最大轴向速度幅值出现在工具杆端面中心轴线下液相区域的中心点附近,其值并不随着驱动力值的增大呈线性增大.铸造实验结果表明,声流作用使铸锭在工具杆端面至铸锭壁面之间形成一条作用区域分界线,分界线两端凝固组织呈现完全不同的样貌,工具杆端面下一侧组织在空化和声流的双重作用下得到细化,呈等轴晶状,而上端组织则呈枝状晶形态.Simulation was made using CFD software Fluent to calculate the flow field of aluminum alloy melt sonicated in a crucible. The results showed that large-scale Eckart acoustic streaming formed in the liquid phase zone under the radiator＇s face, driven by radiation force which formed as a result of acoustic pressure gradient due to viscous attenuation. The maximum axial velocity appeared around the centre of the liquid phase zone in the axial line of the radiator＇s face, and it did not increase linearly with the driving force increasing. Experiment results showed that a borderline in the area from the radiator＇ s face to the boundary of the ingot formed by acoustic streaming. The solidification structure of one side of the borderline was absolutely different from the other＇ s. The structures of the side under the radiator＇s face were all well refined by the duple action of cavitation and acoustic streaming, while the other side＇s were coarse and dendritic.

关 键 词：流场 模拟计算 超声波 声流 辐射力 凝固组织 

分 类 号：TG249.9[金属学及工艺—铸造]