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8th World Congress on Particle Technology 2018: Keynotes and Plenaries

作者： Gan, Jieqing Zhou, Zongyan Yu, Aibing Laboratory for Simulation and Modeling of Particulate Systems Department of Chemical Engineering Monash University VIC3800 Australia

ISBN: (纸本)9781510869769

Combined approach of computational fluid dynamics for gas phase and discrete element method for particles (CFD-DEM) is used to exhibit the formation of expanded bed in gas fluidisation of fine ellipsoids. The results illustrate that in the start-up stage, the bulk disconnects into two major bulks with a lowest contact force on the axial direction, especially for flat and elongated particles. The positions of the lowest point of contact force slightly change with time for oblate and prolate particles, but it moves smoothly from bottom to top for spheres. A slower gas introduction process has a mildest change in bed height (porosity). The fractures between major bulks gradually disappear when the cohesive forces become smaller. In the transition stage, when aspect ratio deviates from 1.0, the pressure drop fluctuation significantly increases. In the stable stage, when the aspect ratio decreases or increases from 1.0, the contact forces and van der Waals forces increases, and the particle-fluid forces become less uniformly distribution in the beds. Ellipsoidal particles undergo an orientation rearrangement during the expansion process. © 2018 8th World Congress on Particle Technology 2018: Keynotes and Plenaries. All rights reserved.

关键词： Aspect ratio

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不同粘性颗粒对卧式螺带混合机混合性能的影响研究

不同粘性颗粒对卧式螺带混合机混合性能的影响研究

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中国计算力学大会2018暨国际华人计算力学大会2018

作者：桂泽东买买提明·艾尼古丽巴哈尔·托乎提哈丽旦·木沙马小晶新疆大学机械工程学院新疆乌鲁木齐830047 Laboratory for Simulation and Modeling of Particulate Systems School of Materials Science and Engine 新疆大学电气工程学院新疆乌鲁木齐830047

本文以卧式螺带颗粒混合机为研究背景,采用离散单元法(Discrete Element Method,DEM)研究叶轮转速和填充率对卧式螺带混合机中不同粘性颗粒混合行为的影响。首先采用Pro/E 软件对卧式螺带混合机进行三维模型创建,然后采用EDEM 软件对混... 详细信息

本文以卧式螺带颗粒混合机为研究背景,采用离散单元法(Discrete Element Method,DEM)研究叶轮转速和填充率对卧式螺带混合机中不同粘性颗粒混合行为的影响。首先采用Pro/E 软件对卧式螺带混合机进行三维模型创建,然后采用EDEM 软件对混合机内颗粒物料混合进行数值模拟,并对其混合效果进行分析。结果表明,对于粘性颗粒和非粘性颗粒混合物,混合速率随着叶轮速度的增加而增加,直到一定的速度后,混合速率会随着叶轮速度的增加混合速度表现出降低的现象。在相同的叶轮转速条件下,混合粘性颗粒时,水平轴向存在颗粒对流现象,颗粒物料沿叶轮转轴周向流动,能有效促进物料颗粒的混合性能;混合非粘性颗粒时,物料颗粒在混合机中存在局部循环流动现象,此现象的发生能抑制整体的混合效果。

关键词：卧式螺带混合机离散单元法粘性颗粒非粘性颗粒物料混合

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Investigation on Cylindrical Particle Position Distribution in Fluidized Bed Using XPTV Method

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Kung Cheng Je Wu Li Hsueh Pao/Journal of Engineering Thermophysics 2017年第7期38卷 1384-1391页

作者： Zhong, Wen-Qi Chen, Xi Yu, Ai-Bing Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education School of Energy and Environment Southeast University Nanjing210096 China Center for Simulation and Modeling of Particulate Systems Southeast University-Monash University Joint Research Institute Suzhou215123 China Department of Chemical Engineering Monash University ClaytonVIC3800 Australia

An X-ray particle tracking velocimetry (XPTV) system is designed and built, and the corresponding tracer particle fabrication method is established. With the XPTV system, the cylindrical particle position and orientation determination method and its error evaluation are investigated. Experimental studies on cylindrical particle position and orientation distribution are carried out based on the aforementioned system and methods. The results show that in bubbling fluidization regime, an internal circulation of cylindrical particles forms in the fluidized bed, and the center axes of most cylindrical particles tend to tilt instead of being vertical. In turbulence fluidization regime, cylindrical particles tend to uniformly disperse across the fluidized bed, and the center axes of most cylindrical particles are vertical. © 2017, Science Press. All right reserved.

关键词： Fluidized beds

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Radical tessellation of the packing of spheres with a log-normal size distribution

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Physical Review E 2015年第3期92卷 032201-032201页

作者： L. Y. Yi K. J. Dong R. P. Zou A. B. Yu Laboratory for Simulation and Modeling of Particulate Systems School of Materials Science and Engineering University of New South Wales Sydney New South Wales 2052 Australia Institute for Infrastructure Engineering University of Western Sydney Penrith New South Wales 2751 Australia Laboratory for Simulation and Modeling of Particulate Systems Department of Chemical Engineering Monash University Clayton Victoria 3800 Australia

The packing of particles with a log-normal size distribution is studied by means of the discrete element method. The packing structures are analyzed in terms of the topological properties such as the number of faces per radical polyhedron and the number of edges per face, and the metric properties such as the perimeter and area per face and the perimeter, area, and volume per radical polyhedron, obtained from the radical tessellation. The effect of the geometric standard deviation in the log-normal distribution on these properties is quantified. It is shown that when the size distribution gets wider, the packing becomes denser; thus the radical tessellation of a particle has decreased topological and metric properties. The quantitative relationships obtained should be useful in the modeling and analysis of structural properties such as effective thermal conductivity and permeability.

关键词： THERMAL conductivity POLYHEDRA PERMEABILITY measurement DISCRETE element method (simulation model) COMPUTER simulation

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Structural characterization of the packings of granular regular polygons

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Physical Review E 2015年第6期92卷 062203-062203页

作者： Chuncheng Wang Kejun Dong Aibing Yu Laboratory for Simulation and Modeling of Particulate Systems Department of Chemical Engineering Monash University Clayton Victoria 3800 Australia Institute for Infrastructure Engineering Western Sydney University Penrith NSW 2751 Australia

By using a recently developed method for discrete modeling of nonspherical particles, we simulate the random packings of granular regular polygons with three to 11 edges under gravity. The effects of shape and friction on the packing structures are investigated by various structural parameters, including packing fraction, the radial distribution function, coordination number, Voronoi tessellation, and bond-orientational order. We find that packing fraction is generally higher for geometrically nonfrustrated regular polygons, and can be increased by the increase of edge number and decrease of friction. The changes of packing fraction are linked with those of the microstructures, such as the variations of the translational and orientational orders and local configurations. In particular, the free areas of Voronoi tessellations (which are related to local packing fractions) can be described by log-normal distributions for all polygons. The quantitative analyses establish a clearer picture for the packings of regular polygons.

关键词： RESEARCH Granular flow Fluid dynamics Centroidal Voronoi tessellations Granular materials Polygons

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Why Have Continuum Theories Previously Failed to Describe Sandpile Formation?

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Physical Review Letters 2014年第6期113卷 068001-068001页

作者： Qijun Zheng Aibing Yu Laboratory for Simulation and Modeling of Particulate Systems School of Materials Science and Engineering The University of New South Wales Sydney New South Wales 2052 Australia Department of Chemical Engineering Monash University Clayton Victoria 3800 Australia

Granular piling may or may not induce a counterintuitive phenomenon of pressure dip at the center of a pile base. Understanding the behavior is a long-standing challenge in granular dynamics modeling. Here we show that the experimental observations of dip or nondip piles can be satisfactorily reproduced by the classic elastoplastic models. Our results demonstrate that (i) dynamic history is a critical factor in the successful description of a piling process and (ii) the dip phenomena are complicated, involving numerous variables associated not only with piling operation but also material properties. Our findings can explain why previous attempts failed to describe piling processes and may open up a new direction to describe granular materials in nature and many industrial processes.

关键词： ELASTOPLASTICITY MANUFACTURING processes MAGNETIZATION OPTICAL pumping MAGNETOOPTICS

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Discrete element modeling of gas fluidization of fine ellipsoidal particles

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AIP Conference Proceedings 2013年第1期1542卷 1130-1133页

作者： Jieqing Gan Zongyan Zhou Ruiping Zou Aibing Yu Laboratory for Simulation and Modeling of Particulate Systems School of Materials Science and Engineering University of New South Wales Sydney New South Wales 2052 Australia

Particle properties are important factors affecting gas fluidization. In the present work, the effects of particle size and shape on the fluidization characteristics are studied using the combined approach of computational fluid dynamics for gas phase and discrete element method for particles. It shows that a bed becomes loosely packed when particle size becomes small. The minimum fluidization velocity increases exponentially with the increase of particle size. Higher minimum bubbling velocities are predicted for ellipsoidal particles compared with spherical ones. “Chain phenomenon” exists in the expanded and fluidized beds for fine prolate particles.

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Numerical study of vertical pneumatic conveying: Effect of friction coefficient

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AIP Conference Proceedings 2013年第1期1542卷 1154-1157页

作者： K. Li S. B. Kuang R. P. Zou R. H. Pan A. B. Yu Laboratory for Simulation and Modeling of Particulate Systems School of Materials Science and Engineering The University of New South Wales Sydney NSW 2052 Australia Longking Bulk Materials Science and Engineering Xiamen 361000 China

This paper presents a numerical study of vertical pneumatic conveying by a combined approach of computational fluid dynamics for gas phase and discrete element method for solid phase. The effects of friction coefficient on the flows in regard with particle flow patterns and their transition, reverse flow, and gas pressure behavior are qualified. The forces acting on particles are analyzed in detail to understand the underlying mechanisms.

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Numerical study of jet-induced cratering of a granular bed: Effect of gravity

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AIP Conference Proceedings 2013年第1期1542卷 1162-1165页

作者： S. B. Kuang C. Q. LaMarche J. S. Curtis A. B. Yu Laboratory for Simulation and Modeling of Particulate Systems School of Materials Science and Engineering The University of New South Wales Sydney NSW 2052 Australia Department of Chemical Engineering University of Florida Gainesville FL 32611 USA

This paper presents a numerical study of jet-induced catering of a granular bed by the combined approach of computational fluid dynamics for gas phase and discrete element method for solid phase. The applicability of the model was verified by the good agreement between measured and predicted temporal crater depths and asymptotic crater profiles, and ishereusedto study the effect of gravity within a wide range. The results show that a decreased gravity can significantly slow down the crater growth and increase the asymptotic crater size. The previously formulated equations respectively for the asymptotic crater depths and widthsat different jet velocities are also valid for those under different gravities.

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Finite element analysis of the contact forces between viscoelastic particles

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AIP Conference Proceedings 2013年第1期1542卷 847-850页

作者： Q. J. Zheng H. P. Zhu A. B. Yu Laboratory for Simulation and Modeling of Particulate Systems School of Materials Science and Engineering The University of New South Wales Sydney NSW 2052 Australia School of Engineering University of Western Sydney Locked Bag 1797 Penrith South DC NSW 1797 Australia

The normal and tangential force-displacement (NFD and TFD) relations as well as the rolling friction between viscoelastic particles are investigated by means of finite element method (FEM). A new set of semi-theoretical models are proposed for the NFD, TFD and rolling friction based on the contact mechanics and the FEM results. Compared with previous empirical models (e.g. Linear-Spring-Dashpot model), the new models have an advantage that all parameters can be directly determined from the material properties. Therefore they can eliminate the uncertainty in parameter selection and should be more effective in discrete element method (DEM) simulations of viscoelastic granular materials.

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