Lehrstuhl für EnergiesystemeTechnische Universität München

N u m e r ic a l S t u d ie s o n P a r t ic le D e p o s it io n

Particle Tracking Code dedicated to CFD data Particle Post-Processing

Dipl.-Ing. Marco Losurdo

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Lehrstuhl für EnergiesystemeTechnische Universität München

O u t lin e

• Who… (about me)• What…(skills, main topics and hopefully capabilities)• Why… (why such areas of interest)• How… (on the numerical approaches)• Examples…

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Lehrstuhl für EnergiesystemeTechnische Universität München

…W h o

• Aerospace Engineering (Rome 2002): Steady-Unsteady CFD Analysis on GT Combustion Chambers…

• Cardiff University (Wales U.K., 2002-2003): (Unsteady CFD Analysis…)

• Ph.D. student TU Delft (2004-2008): Numerical studies on particle deposition – Prof. H. Spliethoff

– Numerical studies on ash deposition, slagging and fouling in PF co-combustor (TU Delft-ECN project)

• Dec. 2008 Ph.D. Defence (hopefully…)

• 2008-2011 TUM

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Lehrstuhl für EnergiesystemeTechnische Universität München

…W h a t

• CFD, Unsteady CFD Combustion – gas phase (background)• Particle Deposition (Ph.D.)

– Particle Deposition theoretical studies: why particles sometime deposit…– Particle Tracking theoretical studies: how to move particles within a CFD mesh– Programming (FORTRAN)

Topics Tackled:

• Particle Tracking: Novel, robust and efficient Algorithm• Collision model: Hard Particle Approach, momenta exchange, instant

impact.• Time dependent deposit properties: Particle Rheology • Particle Mechanic Impaction+Adhesion: Energy Restitution Coefficients

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Lehrstuhl für EnergiesystemeTechnische Universität München

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Lehrstuhl für EnergiesystemeTechnische Universität München

…W h a tAims:• To study solid particles (ash) deposit behavior in CFD fluid dynamics

particle post-processing• To link the mechanical impaction approach for visco-elastic solids

with biomass/solid combustion product fly ash/slagging-fouling to define a detailed and simple deposition criteria particle/wall properties based

• Deposit properties as function of Particle Rheology

ParticleTracking

ViscoElasticModel (VEM)

Mechanical ImpactionRestitution coeff+ +

•Discrete Element Model (DEM): Constant elastic properties

•Visco-Elastic Model (VEM): elastic properties as function of time, temp, composition…

Discrete Elem.Model (DEM)

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Lehrstuhl für EnergiesystemeTechnische Universität München

k

η

ηk

Voigt Model

Maxwell Model

ηk1

Standard Linear Solid (SLS)

k2

Wall, Particle or Thermal stressparticle thermal history

SLS model: E = K1 + K2 ∙ e(-time/(η/E))

…W h a t

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Lehrstuhl für EnergiesystemeTechnische Universität München

V E M A lg o r it h m

1. Calculate particle viscosity η=η(c,T)2. Calculate E as E=E(η,τ)

SLS model: E = K1 + K2 e∙ (-time/( /E))η

• Calculate restitution coeff, in case of impaction• Bounce off or stopstick

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Lehrstuhl für EnergiesystemeTechnische Universität München

Low TemperatureTp < Tg-300

High TemperatureTp > Tg-300

( )V is c o E la s t ic M o d e ls V E M

Young Modulus

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Lehrstuhl für EnergiesystemeTechnische Universität München

…W h yParticle motion mainly concerns:• Air flow conditioning dust• Crystallization Crystals in cooling solutions• Solid and liquid fuel combustion deposition• Granular Separation Sand Column (example)• Granular Problems particle-particle interaction• Medical Application aerosol (example), drugs particle packing

• Commercial CFD codes provide a wide range of solutions but implementing new and advanced or ad hoc deposition models is not always possible

• Developing an in-house Lagrangian particle tracking code has provided a deeper knowledge of commercial CFD code capabilities and limits as well as a better understanding of deposition phenomena in several different applications.

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Lehrstuhl für EnergiesystemeTechnische Universität München

…H o w

Commercial CFD(FLUENT, CFX…)

ParticlePost-Processor(Fortran code)

Enhance CFD capability

Graphic Post-Processor (Tecplot)

Export File

Particle Tracking

Particle Deposition

Deposit Growth

P3 Pre-ProcessorGrid

Reconstruction

Steady PT Unsteady PT

P3 ProcessorP3 Post-ProcessorSteady/Unsteady PT

Move MeshGrid Node Position Update

Real TimeDeposit Evaluation

RTDE AlgorithmUnsteady PT only

Complete/Reduced Domain

P3 CodeCFD computation

CFD

Particle Tracking

Deposition

New Grid

P3

Step - RANS

SandDeposition

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Lehrstuhl für EnergiesystemeTechnische Universität München

CFD

Particle Tracking

Deposition

New Grid

P3

Step - RANS

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Lehrstuhl für EnergiesystemeTechnische Universität München

S lu r r y

Salt Glass

S c r a p e r

Prof. Camilo RindtTU Eindoven

4 m

1.5

m

Upward stream

Downward stream

RANS CFD S a n d S e p a r a t io n C o lu m n( . . , )D r F D i M a io T U D C iv il E n g in e e r in g

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Lehrstuhl für EnergiesystemeTechnische Universität München

RANS 30 l/min, k-omega20-10 μm aerosol particles22% deposition, fairly agreement with exp

Simulations done on 2, 5, 10, 15, 20 μm

-Id e a liz e d M o u t h T h r o a t