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A new constitutive and numerical model for arching of cohesive powders in hoppers

A new constitutive and numerical model for arching of cohesive powders in hoppers

Su, Carmen Jiawen (2017) A new constitutive and numerical model for arching of cohesive powders in hoppers. PhD thesis, University of Greenwich.

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Abstract

Deaths and casualties caused by silo collapses have happened across the industry over the world, especially in production plants which store and handle fine powder. The collapses not only cost financially to settle for compensation, also cost companies' reputation and credibility for partnership. Industry experts believe that the high frequency of silo failures are mainly due to “shortcomings in one or more of four categories: design, construction, usage, and maintenance". However, there is one category has been overlooked by industry, it is the technology in storage, flow and handling of fine powder.

This thesis studies the technology within the area of flow and handling of find powder. Whether or not a cohesive powder would freely discharge through a given orifice is a question at the centre of numerous bulk solids handling issues encountered in industry. The work in this thesis contributes towards answering the question by using a combination of empirical powder property determination and numerical simulation.

Cohesive arching at the outlet is a formation of an arch of cohesive powder (usually fine powder) at the smallest cross-section of a flow channel in a silo (usually the outlet). If it builds up the material inside of the silo, it can potentially cause the failure of the silo by material overload.

The aim of the research is to establish a precise and cost-effective constitutive model that is able to predict the cohesive arching and stress condition in a silo. The numerical simulation is conducted under Finite Element (FE) approach developed and coded in a numerical solver PHYSICA, new concepts and variables to address the discrepancy between the field of powder mechanics and numerical simulation.

Item Type: Thesis (PhD)
Uncontrolled Keywords: Powder mechanics theory; numerical models; PHYSICA; powder property determination; computational fluid dynamics (CFD); finite element method (FEM);
Subjects: Q Science > QC Physics
T Technology > TA Engineering (General). Civil engineering (General)
Faculty / Department / Research Group: Faculty of Engineering & Science
Faculty of Engineering & Science > Department of Engineering Science
Last Modified: 12 Apr 2019 13:57
Selected for GREAT 2016: None
Selected for GREAT 2017: None
Selected for GREAT 2018: None
Selected for GREAT 2019: None
URI: http://gala.gre.ac.uk/id/eprint/23575

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