摘要
水泥3D打印时,水泥浆体在喷头内的流动性对挤出成型有重要影响。以水泥、水、聚羧酸减水剂、改性棒土和纤维素醚作为原始打印材料,根据流变特性测试,采用Herschel-Bulkley模型作为水泥浆体的流变模型,并利用多松弛时间的格子Boltzmann方法(MRT-LBM)对浆体在喷头中的流动进行了分析,引入矩函数来描述松弛过程中的碰撞步,并利用泊肃叶流的理论解对MRT模型进行了验证。在进行实际仿真时,以雷诺数作为准则进行物理单位和格子单位之间的转换,获得相关的流线图和速度场分布图。结果表明:水泥浆体在螺槽截面的流动呈现环流形状,环流的中心在(0.5W,0.7h)位置处;根据速度场的分布,在螺槽横截面的左下角和右下角不存在流体流动,适当增大螺杆速度或螺槽宽度有助于水泥浆体在螺槽内的有效输送。
The flow of the cement paste in the extruder has an important effect on the extruding in the cement-3D printing.The flow of the cement paste in the extruder was analyzed with the multiple-relaxation-time lattice Boltzmann method （MRT-LBM）,in which the original printing materials were cement,water,polycarboxylate superplasticizer,modified attapulgite and cellulose ether,and Herschel-Bulkley model was taken as the rheological model of the cement paste in the rheological test.The moment function was introduced to express the relaxation process in the collision step.MRT-LBM was validated by the theoretical solution of the Poiseuille flow.When it was applied into the cement paste in the extruder,the units of the corresponding physical quantities were converted by taking Reynolds number as the similarity criterion,and the streamlines and the velocity distributions along different directions could be obtained.Results showed that the flow of the cement paste in the extruder section was an annular shape.The center was at position of （0.5 W ,0.7 h ）.According to the velocity distributions,there was no flow at the left bottom and right bottom of the section.Increasing the rotation speed or widening the screw properly contributed to the more effective transport of the cement paste.
作者
吴伟伟
黄筱调
方成刚
李媛媛
WU Weiwei;HUANG Xiaodiao;FANG Chenggang;LI Yuanyuan(Jiangsu Key Laboratory of Digital Manufacturing for Industrial Equipment and Control Technology,College of Mechanical and Power Engineering,Nanjing Tech University,Nanjing 211800,China)
出处
《南京工业大学学报（自然科学版）》
CAS
北大核心
2018年第5期79-84,共6页
Journal of Nanjing Tech University(Natural Science Edition)
