A Coupled DEM/CFD Analysis of the Effect of Air on Powder Flow During Die Filling
A Coupled DEM/CFD Analysis of the Effect of Air on Powder Flow During Die Filling
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DOI：
10.1002/aic.11734
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发表时间：
2009-01-01
期刊：
影响因子：
3.7
通讯作者：
Seville, J. P. K.
中科院分区：
文献类型：
--
作者：
Guo, Y.;Kafui, K. D.;Seville, J. P. K.
使用欧拉-拉格朗日模型对真空和存在空气的情况下固定鞋的模具填充进行了数值分析，该模型对颗粒采用离散元法 (DEM)，对空气采用计算流体动力学 (CFD)，并采用双向空气-颗粒相互作用耦合项。对单分散和多分散粉末系统进行了模拟，以探索空气存在对模具填充过程的影响。对于单分散粉末的模具填充，探讨了颗粒尺寸和密度对流动行为的影响。数值模拟表明，空气的存在对粉末流动行为有显着影响，特别是对于具有较小和/或较轻颗粒的系统。流动以无量纲质量流量来表征，并且已经表明，对于真空中的模具填充来说，这是恒定的。空气中模具填充的流动特性可分为两种状态。存在空气惰性状态，其中颗粒尺寸和密度足够大，使得气流的影响可以忽略不计，并且无量纲质量流量基本上与在真空中填充模具所获得的质量流量相同。对于较小的颗粒尺寸和较低的颗粒密度，还存在空气敏感状态，其中无量纲质量流量随着颗粒尺寸和密度的增加而增加。还研究了粒度分布和粘附力对流动行为的影响。研究发现，在真空中，多分散系统的无量纲质量流量速率几乎与单分散系统相同。在空气存在的情况下，与单分散系统相比，多分散系统获得了更低的无量纲质量流量，这表明空气效应变得更加显着。此外，正如预期的那样，无量纲质量流量随着表面能的增加而降低（即对于更具粘性的粉末）。 (C) 2008 美国化学工程师学会 AIChE J, 55: 49-62, 2009
Die filling from a stationary shoe in a vacuum and in the presence of air was numerically, analyzed using an Eulerian-Lagrangian model, which employs a discrete element method (DEM) for the particles and computational fluid dynamics (CFD) for the air with a two-way air-particle interaction coupling term. Monodisperse and polydisperse powder systems have been simulated to explore the effect of the presence of air on the die filling process. For die filling with monodisperse powders, the influences of particle size and density on the flow behavior were explored. The numerical simulations revealed that the presence of air has a significant impact on the powder flow behavior, especially for systems with smaller and/or lighter particles. Flow has been characterized in terms of a dimensionless mass flow rate, and it has been shown that for die filling in a vacuum this is constant. The flow characteristics for die filling in air can be classified into two regimes. There is an air-inert regime in which the particle size and density are sufficiently large that the effect of air flow becomes negligible, and the dimensionless mass flow rate is essentially identical to that obtained for die filling in a vacuum. There is also an air-sensitive regime, for smaller particle sizes and lower particle densities, in which the dimensionless mass flow rate increases as the particle size and density increase. The effects of particle-size distribution and adhesion on the flow behavior have also been investigated. It was found that, in a vacuum, the dimensionless mass flow, rate for polydisperse systems is nearly identical to that for monodisperse systems. In the presence of air, a lower dimensionless mass flow rate is obtained for polydisperse systems compared to monodisperse systems, demonstrating that air effects become more significant. Furthermore, it has been shown that, as expected, the dimensionless mass flow rate decreases as the surface energy increases (i.e., for more cohesive powders). (C) 2008 American Institute of Chemical Engineers AIChE J, 55: 49-62, 2009