Settling velocity of equiaxed dendrites in a tube  

作　　者：周鹏 王猛 林鑫 黄卫东 

机构地区：[1]State Key Laboratory of Solidification Processing, Northwestern Polytechnical University

出　　处：《Chinese Physics B》2013年第1期518-523,共6页中国物理B（英文版）

基　　金：Project supported by the National Basic Research Program of China (Grant No. 2011CB10402);the National Natural Science Foundation of China (Grant Nos. 50901061 and 50971102);the Foundation of State Key Laboratory of Solidification Processing, China (Grant Nos. 02-TZ-2008 and 36-TP-2009)

摘　　要：The settling velocity of equiaxed dendrites can cause macrosegregation and influence the structure of the equiaxed zone during the casting solidification process. So an understanding of the settling characteristics is needed to predict the structure and segregation in castings. The settling velocity of NH4Cl equiaxed dendrites of non-spherical geometry was studied experimentally in an NH4Cl-70wt.%H2O solution. A calculation formula was proposed to calculate the settling velocity of sediment equiaxed dendrites in a tube filled with saturated solution at a moderate Reynolds number region. The retardation effects of the wall and morphology of the equiaxed dendrite on the settling velocity were taken into account in the development of the calculation formula, and the correction function B of the drag coefficient with consideration of the retardation effects of the wall and morphology of the equiaxed dendrite on the settling velocity of the equiaxed dendrite was calibrated according to the experimental results. A comparison showed that the formula has a good accordance with the experimental results.The settling velocity of equiaxed dendrites can cause macrosegregation and influence the structure of the equiaxed zone during the casting solidification process. So an understanding of the settling characteristics is needed to predict the structure and segregation in castings. The settling velocity of NH4Cl equiaxed dendrites of non-spherical geometry was studied experimentally in an NH4Cl-70wt.%H2O solution. A calculation formula was proposed to calculate the settling velocity of sediment equiaxed dendrites in a tube filled with saturated solution at a moderate Reynolds number region. The retardation effects of the wall and morphology of the equiaxed dendrite on the settling velocity were taken into account in the development of the calculation formula, and the correction function B of the drag coefficient with consideration of the retardation effects of the wall and morphology of the equiaxed dendrite on the settling velocity of the equiaxed dendrite was calibrated according to the experimental results. A comparison showed that the formula has a good accordance with the experimental results.

关 键 词：equiaxed dendrite settling velocity morphology effect wall effect 

分 类 号：TG21[金属学及工艺—铸造]