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Modeling of aerodynamic particle interaction

Jadoon, Asim LU (2010)
Abstract
The purpose of the current study is to investigate the effect of particle-pair interaction for various

separation distances and angular positions. The results obtained are used in a

particle-laden turbulent jet flows in order to improve the existing Lagrangian

Particle Tracking (LPT) models.



In the first part, a detailed numerical study of particle interaction is carried out by

varying the separation distances and angular positions between two-spherical-particles for wide range of Reynolds

numbers. Different factors like drag, lift, wake structures, flow patterns and shedding frequencies are

investigated. Volume of Solid (VOS) method based on Volume of Fluid (VOF) is... (More)
The purpose of the current study is to investigate the effect of particle-pair interaction for various

separation distances and angular positions. The results obtained are used in a

particle-laden turbulent jet flows in order to improve the existing Lagrangian

Particle Tracking (LPT) models.



In the first part, a detailed numerical study of particle interaction is carried out by

varying the separation distances and angular positions between two-spherical-particles for wide range of Reynolds

numbers. Different factors like drag, lift, wake structures, flow patterns and shedding frequencies are

investigated. Volume of Solid (VOS) method based on Volume of Fluid (VOF) is used to represent the particles.



Separation distances Do between the particles is varied from 1.5 to 12D (D being diameter of particle) and the angle is varied from 0 to 180. A wide range of Reynolds numbers from 10 to 600 are used.

Independent of Reynolds number, greatest reduction in drag of trailing sphere is observed in tandem position i.e. when placed in the

wake of leading or reference sphere and the effect can be seen even up to large separation distances of 12D.

However in all positions other than tandem, the interaction effects can only be observed up to Do = 6D. The change

in separation distance and angular position also affects both the magnitude and the direction of lift force. As

the angular position is changed from 0 to 90, the direction of the lift force between two spheres changes from attraction to repulsion.

The wake structures and flow are substantially altered at small separation distances of Do < 3D.

Keeping the separation distance constant, increasing the Reynolds number upto 200 results in a delay in recovery

of the sphere drag when placed in tandem arrangement. For a Reynolds number of 250, the downstream sphere undergoes greater reduction in drag upto Do less than equal to 3D and early recovery for

Do > 3D compared to Re less than equal to 200. In the unsteady region i.e Re > 275-280, increasing the Reynolds number from 300 to 600 results in a greater reduction of drag of the downstream sphere at small separation distances i.e. Do < 2D and also a faster recovery of the drag for Do > 2D. Lift, wake structures and shedding frequencies are also observed to be

strongly dependent on the separation distance and angular positions of particles.



The results indicate the importance of particle interaction in the

modeling of multi-phase flows even in the case of rather dilute flows, i.e. large

inter-particle distances. This emphasis the need of including the drag and the lift

forces in modeling multi-phase flows with Lagrangian Particle Transport (LPT).

Based on separation distance and angle, drag and lift corrections are tabulated for different Reynolds number

from 10 to 600. The corrections are incorporated

in two-phase turbulent jet flows as a modifying factors for drag and lift forces in particle equation of motion.

The effect of aerodynamic interaction is then analyzed by varying the Stokes numbers

and mass loadings. The aerodynaimc effect

is largely dependent on Stokes number and particle number density and is effective in dilute flows with void fraction on the

order of 10^{-4}. The effect on particle dynamics is only observed in

the radial direction at Stokes number of 314 and 50 resulting in enhanced dispersion of

the particles. However, at a relatively low Stokes number flow (10), the effect is found in

the axial direction also. In addition particles gain high radial velcoities which results in more dispersion compared to cases

excluding aerodynamic interaction. The rms of axial velcoity fluctuations for the

continuous phase along the axis of the jet is found to be large, resulting in faster decay of the axial velocity and

higher radial velcoity in three-way case. The results will help in understanding and improving the current multi-phase models. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Soldati, Alfredo, Professor of Chemical Engineering Center for Fluid Mechanics & Hydraulics, Dept. of Energy Technology, University of Udine, Italy
organization
publishing date
type
Thesis
publication status
published
subject
pages
197 pages
defense location
Room M:B, M-building, Ole Römers väg 1, Lund University Faculty of Engineering
defense date
2010-05-21 10:15
ISSN
0282-1990
language
English
LU publication?
yes
id
cb7c6fbc-2ed8-41ba-87c4-917eed800db6 (old id 1593127)
date added to LUP
2010-04-27 15:12:41
date last changed
2016-09-19 08:45:01
@misc{cb7c6fbc-2ed8-41ba-87c4-917eed800db6,
  abstract     = {The purpose of the current study is to investigate the effect of particle-pair interaction for various<br/><br>
separation distances and angular positions. The results obtained are used in a<br/><br>
particle-laden turbulent jet flows in order to improve the existing Lagrangian<br/><br>
Particle Tracking (LPT) models.<br/><br>
<br/><br>
In the first part, a detailed numerical study of particle interaction is carried out by<br/><br>
varying the separation distances and angular positions between two-spherical-particles for wide range of Reynolds<br/><br>
numbers. Different factors like drag, lift, wake structures, flow patterns and shedding frequencies are <br/><br>
investigated. Volume of Solid (VOS) method based on Volume of Fluid (VOF) is used to represent the particles.<br/><br>
<br/><br>
Separation distances Do between the particles is varied from 1.5 to 12D (D being diameter of particle) and the angle is varied from 0 to 180. A wide range of Reynolds numbers from 10 to 600 are used.<br/><br>
Independent of Reynolds number, greatest reduction in drag of trailing sphere is observed in tandem position i.e. when placed in the<br/><br>
wake of leading or reference sphere and the effect can be seen even up to large separation distances of 12D.<br/><br>
However in all positions other than tandem, the interaction effects can only be observed up to Do = 6D. The change<br/><br>
in separation distance and angular position also affects both the magnitude and the direction of lift force. As<br/><br>
the angular position is changed from 0 to 90, the direction of the lift force between two spheres changes from attraction to repulsion.<br/><br>
The wake structures and flow are substantially altered at small separation distances of Do &lt; 3D.<br/><br>
Keeping the separation distance constant, increasing the Reynolds number upto 200 results in a delay in recovery<br/><br>
of the sphere drag when placed in tandem arrangement. For a Reynolds number of 250, the downstream sphere undergoes greater reduction in drag upto Do less than equal to 3D and early recovery for<br/><br>
Do &gt; 3D compared to Re less than equal to 200. In the unsteady region i.e Re &gt; 275-280, increasing the Reynolds number from 300 to 600 results in a greater reduction of drag of the downstream sphere at small separation distances i.e. Do &lt; 2D and also a faster recovery of the drag for Do &gt; 2D. Lift, wake structures and shedding frequencies are also observed to be<br/><br>
strongly dependent on the separation distance and angular positions of particles.<br/><br>
<br/><br>
The results indicate the importance of particle interaction in the <br/><br>
modeling of multi-phase flows even in the case of rather dilute flows, i.e. large<br/><br>
inter-particle distances. This emphasis the need of including the drag and the lift<br/><br>
forces in modeling multi-phase flows with Lagrangian Particle Transport (LPT).<br/><br>
Based on separation distance and angle, drag and lift corrections are tabulated for different Reynolds number<br/><br>
from 10 to 600. The corrections are incorporated<br/><br>
in two-phase turbulent jet flows as a modifying factors for drag and lift forces in particle equation of motion.<br/><br>
The effect of aerodynamic interaction is then analyzed by varying the Stokes numbers<br/><br>
and mass loadings. The aerodynaimc effect<br/><br>
is largely dependent on Stokes number and particle number density and is effective in dilute flows with void fraction on the<br/><br>
order of 10^{-4}. The effect on particle dynamics is only observed in <br/><br>
the radial direction at Stokes number of 314 and 50 resulting in enhanced dispersion of<br/><br>
the particles. However, at a relatively low Stokes number flow (10), the effect is found in<br/><br>
the axial direction also. In addition particles gain high radial velcoities which results in more dispersion compared to cases<br/><br>
excluding aerodynamic interaction. The rms of axial velcoity fluctuations for the<br/><br>
continuous phase along the axis of the jet is found to be large, resulting in faster decay of the axial velocity and<br/><br>
higher radial velcoity in three-way case. The results will help in understanding and improving the current multi-phase models.},
  author       = {Jadoon, Asim},
  issn         = {0282-1990},
  language     = {eng},
  pages        = {197},
  title        = {Modeling of aerodynamic particle interaction},
  year         = {2010},
}