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A coupled DEM/CFD analysis of die filling process

Guo, Yu (2010)
Ph.D. thesis, University of Birmingham.

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Abstract

This thesis reports numerical analyses of powder flow, mixing and segregation behavior during die filling in a vacuum and in air 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. The effects of air and particle properties (size, density, size distribution, cohesion etc.) on powder flow are explored. The results are in a good agreement with experimental observations. Powder flow is characterized in terms of a dimensionless mass flow rate and a critical filling velocity. When air is present, the powder flow characteristics depend on the particle size and density and can be classified into an air-sensitive regime and an air-inert regime. It is found that the difference in particle size and/or density can cause segregation during die filling. Therefore, parametric studies are undertaken to examine the effects of some factors, such as particle size or density ratio, shoe speed, initial mass fraction of fine particles, initial height of powder bed and cohesion. Suction filling with a movable punch is also simulated. It has been shown that the utilization of suction can significantly improve the powder flow rate and reduce the density-induced segregation.

Type of Work:Ph.D. thesis.
Supervisor(s):Wu, Charley
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:School of Chemical Engineering
Keywords:Discrete Element Method, Computational Fluid Dynamics, air effect, powder flow, segregation, suction, die filling
Subjects:TP Chemical technology
TJ Mechanical engineering and machinery
Institution:University of Birmingham
ID Code:674
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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