Numerical investigation on flow process of liquid metals in melt delivery nozzle during gas atomization process for fine metal powder production
(1. Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen 518055, China;
2. Shenzhen Key Laboratory for Additive Manufacturing of High-performance Materials, Shenzhen 518055, China;
3. Hunan Industrial Technical Center Co., Ltd., Changsha 410201, China;
4. Academy for Advanced Interdisciplinary Studies, Southern University of Science and Technology, Shenzhen 518055, China)
2. Shenzhen Key Laboratory for Additive Manufacturing of High-performance Materials, Shenzhen 518055, China;
3. Hunan Industrial Technical Center Co., Ltd., Changsha 410201, China;
4. Academy for Advanced Interdisciplinary Studies, Southern University of Science and Technology, Shenzhen 518055, China)
Abstract: Based on volume of fluid (VoF) interface capturing method and shear-stress transport (SST) k-ω turbulence model, numerical simulation was performed to reveal the flow mechanism of metal melts in melt delivery nozzle (MDN) during gas atomization (GA) process. The experimental validation indicated that the numerical models could give a reasonable prediction on the melt flow process in the MDN. With the decrease of the MDN inner-diameter, the melt flow resistance increased for both molten aluminum and iron, especially achieving an order of 102 kPa in the case of the MDN inner-diameter ≤1 mm. Based on the conventional GA process, the positive pressure was imposed on the viscous aluminum alloy melt to overcome its flow resistance in the MDN, thus producing powders under different MDN inner-diameters. When the MDN inner-diameter was reduced from 4 to 2 mm, the yield of fine powder (<150 μm) soared from 54.7% to 94.2%. The surface quality of powders has also been improved when using a smaller inner-diameter MDN.
Key words: gas atomization; melt delivery nozzle; liquid metal; flow resistance; metal powder