冷却倾斜板熔体处理过程边界层分布及流动传热的理论研究  

Theoretical study on boundary distributions and flow-metal heat transfer during melt treatment by cooling sloping plate

作　　者：管仁国[1] 赵占勇[1] 黄红乾[1] 连超[1] 钞润泽[1] 刘春明[1] 

机构地区：[1]东北大学材料与冶金学院,沈阳110004

出　　处：《物理学报》2012年第20期367-375,共9页Acta Physica Sinica

基　　金：国家优秀青年科学基金(批准号:51222405);国家自然科学基金重点项目(批准号:51034002);国家自然科学基金(批准号:50974038);霍英东基金会青年教师基金(批准号:132002);国家重点基础研究发展计划(批准号:201 1CB610405)资助的课题~~

摘　　要：针对倾斜板熔体处理晶粒细化与半固态成形原理,研究了倾斜板熔体处理过程边界层分布,建立了熔体传热和冷却速率的计算模型.计算结果表明,随着斜板倾角和熔体初始流动速度的增大,熔体在倾斜板上从层流向紊流的转变时间减少;温度边界层厚度随着熔体初始流动速度的增加而减小,斜板倾角对温度边界层厚度的影响较小;温度边界层厚度和速度边界层厚度都随熔体流动距离的增加而增大,在层流区,温度边界层厚度远大于速度边界层厚度,而在紊流区,温度边界层厚度与速度边界层厚度重合;倾斜板上熔体冷却速率与熔体厚度成反比,初始流速小于1m/s时,熔体的冷却速率沿着倾斜板长度方向逐渐增大,初始流速为1m/s时,熔体的冷却速率沿倾斜板长度方向基本不变,当初始流速大于1m/s时,熔体冷却速率沿倾斜板长度方向逐渐减小;倾斜板上熔体冷却速率在100—1000 K/s之间,属于亚快速凝固范畴.In this paper, according to the principle of grain refining and semisolid forming by cooling sloping plate process, the distributions of boundary layers during melt treatment by the sloping plate are studied, and mathematic models of heat transfer and cooling rate are established. Calculation results show that the change time from laminar flow to turbulent flow decreases with the increases of the sloping angle and initial flow velocity. The thickness of temperature boundary layer decreases with the increases of initial flow velocity. The effect of the sloping angle on the thickness of temperature boundary is small. The boundary layer thicknesses of the both temperature and velocity increase with the increase of the flow distance gradually. In the laminar flow region, the thickness of the temperature boundary layer is much bigger than that of the velocity boundary layer, while the two layers coincide with each other in the turbulent flow zone. The melt cooling rate on the sloping plate and the melt thickness have an inverse proportion relationship between each other. When the initial flow velocity is lower than 1 rn/s the cooling rate increases along the sloping plate gradually. While the initial flow velocity is 1 m/s, the cooling rate dose not change approximately. However, when the initial flow velocity is larger than lm/s the cooling rate decreases along the sloping plate gradually. The melt cooling rate on the cooling sloping plate is between 100 K/s and 1000 K/s, which belongs to meta-rapid solidification scope.

关 键 词：半固态 晶粒细化 倾斜板 冷却速率 

分 类 号：TG21[金属学及工艺—铸造]