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Modelling and Characterisation of Granular Material Flow
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Mechanics of Solid Materials.
2017 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Granular materials are very common both in nature and in industry, and their extensive use means that there are financial incentives for increased efficiency. There are huge costs related to their use and handling, which is a major motivation for increased knowledge of the behaviour of granular materials at different loading conditions. The development of tools for numerical simulation of granular materials at diverse flow conditions gives the opportunity to study and optimise various industrial processes. In order for such tools to be trustworthy, calibration and validation against experimental results is essential. Thus, experimental methods for accurate measurement and characterisation of granular material flow are required. The objective of this thesis is to contribute to the knowledge of experimental characterisation and numerical modelling of non-cohesive, dry granular materials, at dissimilar flow conditions. In order to fulfil this objective, an experimental method, able to capture the flow behaviour of granular materials is developed. The method is based on the digital image correlation technique, and it is used for field measurements of displacement and velocity. The devised method is used to obtain field measurements for the flow of sand, tungsten carbide powder and potassium chloride. For modelling and simulation, the smoothed particle hydrodynamics (SPH) method, and a pressure-dependent, elastic-plastic constitutive model are used.

In this thesis, experimental characterisation and numerical modelling of granular material flow is performed in a number of applications. An experimental powder filling rig is used to study the flow during filling of sand into a die. A high-speed digital camera is used to record the flow, and the digital image correlation technique is used to obtain field measurements during the filling. This method is also applied in another experimental setup, where flow during filling of spherical tungsten carbide powder into a die is studied. The filling of tungsten carbide powder is simulated using the SPH method, and the results are compared to the field measurements with good agreement. Furthermore, the flow of potassium chloride is studied experimentally in the collapse of a granular column and in the discharge from a flat bottomed silo. The material flow process in both the column collapse and silo discharge are simulated using the SPH method. The results from simulations are found to be in agreement with observations reported in literature, and with experimental measurements obtained in this work. In conclusion, an experimental method for characterising granular material flow through field measurements is presented. The method is used to support the exploration of numerical tools for modelling and simulation of granular material flow. Furthermore, the high accuracy field measurements are used for improved calibration and validation of numerical methods. Reliable numerical simulations allows for study of the mechanisms that are present during granular material flow, mechanisms that might be hard or even impossible to investigate experimentally. The work within the present thesis contributes to the knowledge of both experimental characterisation and numerical modelling of granular material flow.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2017.
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
URN: urn:nbn:se:ltu:diva-62670ISBN: 978-91-7583-853-3 (print)ISBN: 978-91-7583-854-0 (electronic)OAI: oai:DiVA.org:ltu-62670DiVA: diva2:1084360
Presentation
2017-06-16, E231, Luleå, 10:00
Available from: 2017-03-28 Created: 2017-03-24 Last updated: 2017-05-31Bibliographically approved
List of papers
1. Experimental methodology for study of granular material flow using digital speckle photography
Open this publication in new window or tab >>Experimental methodology for study of granular material flow using digital speckle photography
Show others...
2016 (English)In: Chemical Engineering Science, ISSN 0009-2509, E-ISSN 1873-4405, Vol. 155, 524-536 p.Article in journal (Refereed) Published
Abstract [en]

Granular material flow occurs in many industrial applications, and the characteristics of such flow is challenging to measure. Therefore, an experimental method that captures the flow behavior at different loading situations is desired.

In this work, experimental measurements of granular material flow with digital speckle photography (DSP) are carried out. The granular flow process is recorded with a high-speed camera; the image series are then analyzed using the DSP method. This approach enables field data such as displacement, velocity, and strain fields to be visualized during the granular material flow process. Three different scenarios were studied: free surface flow in a fill shoe, flow without a free surface in a fill shoe, and the rearrangement of material in a cavity. The results showed that it is possible to obtain field data of the motion of particles for all three scenarios with the DSP technique. The presented experimental methodology can be used to capture complex flow behavior of granular material.

National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-59694 (URN)10.1016/j.ces.2016.09.010 (DOI)000385600400045 ()2-s2.0-84987642035 (Scopus ID)
Note

Validerad; 2016; Nivå 2; 2016-10-12 (andbra)

Available from: 2016-10-12 Created: 2016-10-12 Last updated: 2017-03-24Bibliographically approved
2. Study of Powder Filling Using Experimental and Numerical Methods
Open this publication in new window or tab >>Study of Powder Filling Using Experimental and Numerical Methods
2016 (English)Conference paper, (Refereed)
Abstract [en]

This work covers both experimental measurements and numerical modelling of powder filling. Experimental measurements with digital speckle photography (DSP) are used to study powder flow during die filling. DSP measurements are realized by recording the powder filling process with a high speed video camera. The image series are then evaluated using an image correlation technique. By this, velocity and strain field data during the filling process can be visualised. DSP measurements are also supporting the development of a numerical model of the process. In this work the smoothed particle hydrodynamics (SPH) method is used to model the powder filling process. The numerical results are similar compared to the DSP measurements when comparing velocity fields during powder filling. The SPH model is further used to evaluate the density distribution after filling. Experimental measurements combined with simulation are powerful tools to increase the knowledge of the powder filling process.

National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-60482 (URN)
Conference
World PM2016 Congress & Exhibition, Hamburg, October 9-13 2016
Available from: 2016-11-16 Created: 2016-11-16 Last updated: 2017-03-24Bibliographically approved
3. Experimental and numerical study of granular material flow using particle methods: application in handling of potassium chloride (KCl)
Open this publication in new window or tab >>Experimental and numerical study of granular material flow using particle methods: application in handling of potassium chloride (KCl)
(English)Manuscript (preprint) (Other academic)
National Category
Applied Mechanics
Research subject
Solid Mechanics
Identifiers
urn:nbn:se:ltu:diva-62669 (URN)
Available from: 2017-03-24 Created: 2017-03-24 Last updated: 2017-04-03

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