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Numerical study of dynamics of mass-emitting particles in multi-phase flow
KTH, School of Engineering Sciences (SCI), Mechanics, Physicochemical Fluid Mechanics.
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Suspended particles can be found in wide range of industrial applications such as food industry, mining industry and energy conversion processes. Depending on flow cases which particles are involved, different dynamics and motions are expected from suspended particles. In addition, it is well-known that existence of particles alters the configuration of surrounding flow.

Fuel particles are expected to be found to gasify or evaporate in energy conversion processes . Burning (or combustion) of a fuel particle results in the production of a thin film of gas on the surface of the particle. The flow around the particle and existence of the thin film due to the combustion, might be the source of changes in particle-particle interaction, particle interaction with the surrounding fluid and walls. In order to investigate these phenomena, we apply a radial outflow boundary condition on the surface of particles to resemble gasification/evaporation of solid particles or droplet fuels.

To study the effect of outflow from the surface of particles, we consider two generic cases; particles in shear flow and sedimentation of particles. These cases have been studied thoroughly in literature in which both behavior of the particle and pattern of the surrounding flow has been investigated. This provides us an opportunity to analyze our results against these well studied cases. In agreement with previous studies, it is observed that the radial outflow results to a decrease in drag and lift forces and an increase in pressure on the surface of the particle. Thence, a growth in maximum velocity of settling spherical particle and a decay in angular velocity of rotating particle by increasing outflow rate can be observed. Furthermore, a general hindering effect in particles interaction is detected. Considering the configuration of the background flow, different flow streamlines lead to different particle trajectories in a simple shear flow, in existence of outflow from the surface of particles.

In the last part of the thesis we consider 3D simulations of three-phase flow (gas-liquid-particle) in which particle and bubble are moving under external forces and interacting with each other. In this case, we apply a non-wetting boundary condition on the surface of solid particle. A compound consist of a particle entrapped inside a bubble, preforms different behaviors depending on the competition between gravitational and surface tension induced forces.

Regarding the numerical method, we apply a lattice Boltzmann method (LBM) together with momentum exchange approach in order to couple particle and fluid. However, to capture phase interfaces in simulation of three-phase flows, a pseudo-potential method is considered . 

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2018. , p. 50
Series
TRITA-MEK, ISSN 0348-467X ; 2018:07
Keyword [en]
particles with outflow, lattice Boltzmann method, particle interaction, liquid-gas-solid systems, sedimentation, shear flow
National Category
Fluid Mechanics and Acoustics
Research subject
Engineering Mechanics
Identifiers
URN: urn:nbn:se:kth:diva-222612ISBN: 978-91-7729-694-2 (print)OAI: oai:DiVA.org:kth-222612DiVA: diva2:1182069
Public defence
2018-03-09, Kollegiesalen, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Research Council
Note

QC 20180212

Available from: 2018-02-12 Created: 2018-02-12 Last updated: 2018-02-12Bibliographically approved
List of papers
1. Kinematics and dynamics of suspended gasifying particle
Open this publication in new window or tab >>Kinematics and dynamics of suspended gasifying particle
2017 (English)In: Acta Mechanica, ISSN 0001-5970, E-ISSN 1619-6937, Vol. 228, no 3, p. 1135-1151Article in journal (Refereed) Published
Abstract [en]

The effect of gasification on the dynamics and kinematics of immersed spherical and non-spherical solid particles have been investigated using the three-dimensional lattice Boltzmann method. The gasification was performed by applying mass injection on particle surface for three cases: flow passing by a fixed sphere, rotating ellipsoid in simple shear flow, and a settling single sphere in a rectangular domain. In addition, we have compared the accuracy of employing two different fluid-solid interaction methods for the particle boundary. The validity of the gasification model was studied by comparing computed the mass flux from the simulation and the calculated value on the surface of the particle. The result was used to select a suitable boundary method in the simulations combined with gasification. Moreover, the reduction effect of the ejected mass flux on the drag coefficient of the fixed sphere have been validated against previous studies. In the case of rotating ellipsoid in simple shear flow with mass injection, a decrease on the rate of rotation was observed. The terminal (maximum) velocity of the settling sphere was increased by increasing the ratio of radial flux from the particle boundary.

Place, publisher, year, edition, pages
SPRINGER WIEN, 2017
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-205480 (URN)10.1007/s00707-016-1748-5 (DOI)000395107300021 ()2-s2.0-84995783715 (Scopus ID)
Note

QC 20170523

Available from: 2017-05-23 Created: 2017-05-23 Last updated: 2018-02-12Bibliographically approved
2. Interaction of sedimenting mass-ejecting particles
Open this publication in new window or tab >>Interaction of sedimenting mass-ejecting particles
2017 (English)Manuscript (preprint) (Other academic)
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-222609 (URN)
Funder
Swedish Research Council
Note

QC 20180212

Available from: 2018-02-12 Created: 2018-02-12 Last updated: 2018-02-12Bibliographically approved
3. Simulation of spherical particles with outflow from the surface in simple shear flow
Open this publication in new window or tab >>Simulation of spherical particles with outflow from the surface in simple shear flow
(English)Manuscript (preprint) (Other academic)
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-222610 (URN)
Note

QC 20180212

Available from: 2018-02-12 Created: 2018-02-12 Last updated: 2018-02-12Bibliographically approved
4. Study of particle dynamics in three phase flow
Open this publication in new window or tab >>Study of particle dynamics in three phase flow
(English)Manuscript (preprint) (Other academic)
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-222611 (URN)
Note

QC 20180212

Available from: 2018-02-12 Created: 2018-02-12 Last updated: 2018-02-12Bibliographically approved

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