JZUS - Journal of Zhejiang University SCIENCE

Journal of Zhejiang University SCIENCE A

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Enhancing the spatter-removal rate in laser powder-bed fusion using a gas-intake system with dual inlets

Author(s): Xin TIAN, Junwei ZHONG, Youwen YANG, Chaolei ZHANG, Long ZHAO
Affiliation(s): School of Mechanical and Electrical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China; more
Corresponding email(s): jwzhong0@jxust.edu.cn, yangyouwen@jxust.edu.cn
Key Words: Laser powder-bed fusion (L-PBF); Computational fluid dynamics (CFD); Flow field simulation; Structural optimization; Coanda effect

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Abstract: Mounds of spatter are generated in laser powder-bed fusion (L-PBF) additive manufacturing, which reduces build quality and laser lifetime. Due to the lack of supplemental airflow above the chamber, the conventional build chamber with a single gas inlet exhibits a pronounced tendency for gas to flow upward near the outlet. This phenomenon results in the formation of a large vortex within the build chamber. The vortex leads to the chaotic motion trajectory of the spatter in the build chamber. The design defects of the existing build chamber based on dual gas inlets are shown in this paper. We established a coupled computational fluid dynamics-discrete phase model (CFD-DPM) model to optimize the build chamber by adjusting the position and structure of the second gas inlet. The homogeneity of the flow is increased with a distance of 379 mm between the two inlets and a wider-reaching second inlet. The Coanda effect is also crucial in the spatter-removal process. The Coanda effect is reduced by modifying the right sidewall of the build chamber and increasing the pressure difference between the inlet and outlet. Finally, we found that the spatter-removal rate rose from 8.9% to 76.1% between the conventional build chamber with a single gas inlet and the optimized build chamber with two gas inlets.

采用一种双进气口进气系统提高激光粉末床熔融中的飞溅物去除率

作者：田鑫¹，钟骏薇¹，杨友文^1,2，张朝磊¹，赵龙¹
机构：¹江西理工大学，机电工程学院，中国赣州，341000；²南京大学，现代工程与应用科学学院，中国南京，210089
目的：在激光粉末床熔融增材制造中，会产生大量飞溅物，从而降低构建质量和激光寿命。本文旨在探讨激光粉末床融合技术（L-PBF）构建室内惰性保护气流对飞溅物运动的影响。本文提出一种新型构建室的设计方案，以提高激光粉末床熔融中的飞溅物去除率。
创新点：1.建立一个完全耦合的计算流体动力学-离散相模型（CFD-DPM），模拟飞溅物和气流之间的相互作用；2.提出一种新型构建室的设计方案，提高激光粉末床熔融中的飞溅物去除率。
方法：1.通过搭建飞溅物与气流之间相互作用的CFD-DPM模型，模拟气流与飞溅物的轨迹（图4）；2.通过对比分析，对比单个入口与引入第二进气口后构建室内部的气体流动变化，提出优化设计方案（图5）；3.通过结合气体流动速度的均匀度和飞溅物清除效率，模拟对比第二进气口不同位置、第二进气口覆盖范围和柯安达效应的影响，提出改进方案（图6~13）。
结论：1.引入第二进气口可以有效抑制粉末床附近层流向上的运动，使粉末床周围形成更加均匀的层流，为飞溅物产生均匀的拖拽力；2.两进气口之间的距离对层流通过粉末床的均匀性有重要影响，对比分析后推荐两进气口之间的最佳距离为379 mm；3.第二进气口的宽度是影响层流粉末床宽度均匀性的另一个重要因素。通过增加第二进气口的宽度明显改善了流动的均匀性和飞溅物的运动轨迹；4.受柯安达效应的影响，气流右侧的下行气体限制了飞溅高度。将右壁下半部分向外移动并适当提高进出口压差后将飞溅物去除率提高到76.1%。

关键词组：激光粉末床熔融；计算流体力学；流场模拟；结构优化；柯安达效应

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采用一种双进气口进气系统提高激光粉末床熔融中的飞溅物去除率

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