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TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
INTERNAL INTERNAL
COMBUSTION COMBUSTION
ENGINES ENGINES
SIMULATION IN SIMULATION IN
OPENFOAMOPENFOAMTommasoTommaso LucchiniLucchini
DipartimentoDipartimento didi EnergeticaEnergetica,,
POLITECNICO DI MILANOPOLITECNICO DI MILANO
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
TOPICSTOPICS
•• ENGINE SIMULATION IN ENGINE SIMULATION IN OpenFOAMOpenFOAM
oo State of ArtState of Art
oo engineFOAMengineFOAM
oo dieselEngineFOAMdieselEngineFOAM
•• RESULTSRESULTS
oo Engine Case: FiatEngine Case: Fiat--LanciaLancia 16V VIS16V VIS
oo Spray Case: Spray from a pressureSpray Case: Spray from a pressure--swirl Injectorswirl Injector
•• FUTURE DEVELOPMENTS FUTURE DEVELOPMENTS ((collaboration with Dr. collaboration with Dr. JasakJasak))
oo Topology modifiers applied to engine meshesTopology modifiers applied to engine meshes
oo FourFour--Stroke Engines (valve action)Stroke Engines (valve action)
oo Two Stroke EnginesTwo Stroke Engines
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
ENGINE SIMULATIONENGINE SIMULATION
•• COMPLEX PHYSICAL MODELSCOMPLEX PHYSICAL MODELS
oo Compressible (transonic) flowCompressible (transonic) flow
oo Turbulence, Combustion, ChemistryTurbulence, Combustion, Chemistry
oo LagrangianLagrangian Particles for SprayParticles for Spray
•• COMPLEX GEOMETRY HANDLINGCOMPLEX GEOMETRY HANDLING
oo Moving MeshMoving Mesh
oo Topological Changes (valve action)Topological Changes (valve action)
•• MODEL TO MODEL INTERACTIONMODEL TO MODEL INTERACTION
•• NEW PHYSICAL AND NUMERICAL MODELSNEW PHYSICAL AND NUMERICAL MODELS
oo ImplementationImplementation
oo TestingTesting
oo ObjectObject--Oriented StructureOriented Structure
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
ENGINE MODELLING IN OPENFOAMENGINE MODELLING IN OPENFOAM
•• SOLVERSSOLVERS
oo engineFOAMengineFOAM
oo dieselEngineFOAMdieselEngineFOAM
•• engineFOAMengineFOAM
oo SparkSpark--ignition enginesignition engines
oo RANS combustion RANS combustion modelingmodeling of premixed combustionof premixed combustion
oo Weller combustion model (also known as bWeller combustion model (also known as b--ΞΞ))
•• dieselEngineFOAMdieselEngineFOAM
oo Diesel enginesDiesel engines
oo EulerianEulerian--LagrangianLagrangian approach for spray trackingapproach for spray tracking
oo RANS combustion RANS combustion modelingmodeling of nonof non--premixed combustionpremixed combustion
oo Chalmers Partially Stirred Reactor Combustion ModelChalmers Partially Stirred Reactor Combustion Model
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
ENGINE SOLVERSENGINE SOLVERS
Thermodynamic ApproachThermodynamic Approach
Spray particles trackingSpray particles tracking
Chemistry Model for chemical source termsChemistry Model for chemical source terms
Mesh handling and “engine components”Mesh handling and “engine components”
src/thermophysicalModels/combustionsrc/thermophysicalModels/combustion
src/lagrangian/dieselSpraysrc/lagrangian/dieselSpray
src/thermophysicalModels/chemistryModelsrc/thermophysicalModels/chemistryModel
src/OpenFOAM/meshes/fvMeshsrc/OpenFOAM/meshes/fvMesh
src/topoFvMeshsrc/topoFvMesh
srcsrc/engine/engine
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
PREMIXED COMBUSTION (PREMIXED COMBUSTION (engineFOAMengineFOAM))
FLAMELET APPROACH: burnt and unburned gases are FLAMELET APPROACH: burnt and unburned gases are
divided by a thin and wrinkled turbulent flame front.divided by a thin and wrinkled turbulent flame front.
UnburntUnburnt gas properties:gas properties:
TTuu, , hhuu, , ρρuu
Burnt gas properties:Burnt gas properties:
TTbb, , hhbb, , ρρbb
Cell properties:Cell properties:
T, h, T, h, ρρ, p, b, ft, p, b, ft
Laminar flame speed SLaminar flame speed Suu
bb--ΞΞΞΞΞΞΞΞ Combustion Model by WellerCombustion Model by Weller
( ) ( ) bSbDbUt
buub
~~~~~
2 ∇Ξ−=∇∇−∇+∂
∂ρρρ
ρ
solvesolve
((
fvmfvm::::ddtddt((rhorho, b), b)
+ + mvConvectionmvConvection-->>fvmDivfvmDiv((phiphi, b), b)
+ + fvmfvm::::divdiv((phiStphiSt, b, ", b, "divdiv((phiStphiSt,b)"),b)")
-- fvmfvm::::SpSp((fvcfvc::::divdiv((phiStphiSt), b)), b)
-- fvmfvm::::laplacianlaplacian((turbulenceturbulence-->>muEffmuEff(), b)(), b)
););
GulderGulder correlation for laminar flame speed Scorrelation for laminar flame speed Suu
hhuCombustionThermohhuCombustionThermo
inhomogeneousMixtureinhomogeneousMixture
sutherlandTransportsutherlandTransport
specieThermospecieThermo
janafThermojanafThermo
perfectGasperfectGas
laminarFlameSpeedlaminarFlameSpeed
b: normalized fuel fractionb: normalized fuel fraction
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
LAGRANGIAN SPRAY MODELLINGLAGRANGIAN SPRAY MODELLING
INJECTION (INJECTION (injectorModelinjectorModel))
ATOMIZATION (ATOMIZATION (atomizationModelatomizationModel))
BREAKUP (BREAKUP (breakupModelbreakupModel))
EVAPORATION (EVAPORATION (evaporationModelevaporationModel))
COLLISION (COLLISION (collisionModelcollisionModel))
WALL IMPINGEMENT (WALL IMPINGEMENT (wallModelwallModel))
DRAG (DRAG (dragModeldragModel))
HEAT TRANSFER (HEAT TRANSFER (heatTransferModelheatTransferModel))
TURBULENT DISPERSION (TURBULENT DISPERSION (dispersionModeldispersionModel))
The spray is a The spray is a CloudCloud of of parcelsparcels, and evolves according to:, and evolves according to:
MASS, MOMENTUM AND ENERGY EXCHANGE WITH THE GAS PHASEMASS, MOMENTUM AND ENERGY EXCHANGE WITH THE GAS PHASE
ADDITIONAL SUBADDITIONAL SUB--MODELS (MODELS (spraySubModelsspraySubModels))
dieselSpray.evaporationSourcedieselSpray.evaporationSource()()
dieselSpray.momentumSourcedieselSpray.momentumSource()()
dieselSpray.heatTransferSourcedieselSpray.heatTransferSource()()
RUNRUN--TIME SELECTION TABLES ALLOW TO EASILY DEFINETIME SELECTION TABLES ALLOW TO EASILY DEFINE
NEW SPRAY SUBNEW SPRAY SUB--MODELSMODELS
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
DIESEL COMBUSTION (DIESEL COMBUSTION (dieselEngineFOAMdieselEngineFOAM))
TURBULENCETURBULENCE--CHEMISTRY INTERACTIONCHEMISTRY INTERACTION
Partially Stirred Reactor ConceptPartially Stirred Reactor Concept
i
chemmix
chemiRR ω
ττ
τ&
+=
RRRRii : Chemical Source Term: Chemical Source Term
ωωii : Reaction Rate: Reaction Rate
ττchemchem : Chemical Time: Chemical Time
ττmixmix : Mixing Time: Mixing Time
A chemical system has to be solved to provide A chemical system has to be solved to provide ωωωωωωωωii
ODE, Sequential, ODE, Sequential, EulerImplicitEulerImplicit Chemistry solversChemistry solvers
Reaction mechanism in Reaction mechanism in chemkinchemkin or or foamChemistryfoamChemistry formats formats
Cell propertiesCell properties
T, h, T, h, ρρ, p, Y, p, Yii
hCombustionThermohCombustionThermo
reactingMixturereactingMixture
chemistryModelchemistryModel
chemistrySolverchemistrySolver
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
ENGINE MOVING MESHENGINE MOVING MESH
STATE OF ARTSTATE OF ART
Moving and deforming mesh, without topological changesMoving and deforming mesh, without topological changes
Algorithm specified in Algorithm specified in src/engine/include/movePiston.Hsrc/engine/include/movePiston.H
Piston Bowl Points: Piston Bowl Points: Move with piston displacementMove with piston displacement
Liner Points: Liner Points: DeformationDeformation
Head Points: Head Points: Do not moveDo not move
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
RESULTSRESULTS
Gasoline spray emerging from a pressureGasoline spray emerging from a pressure--swirl injector for GDI engines swirl injector for GDI engines
(SAE 2005(SAE 2005--2424--86)86)
t = 1.0 mst = 1.0 ms t = 2.0 mst = 2.0 ms t = 3.0 mst = 3.0 ms
FiatFiat--LanciaLancia 16V ENGINE, prediction of the pressure history 16V ENGINE, prediction of the pressure history
(to be published at the SAE 2006 World Congress)(to be published at the SAE 2006 World Congress)
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
DEVELOPMENT: ENGINE MESHDEVELOPMENT: ENGINE MESH
Mesh aspect ratio should be kept as more constant as Mesh aspect ratio should be kept as more constant as
possible, also reducing the number of cells the possible, also reducing the number of cells the
computational time decreases….computational time decreases….
ADDITION/REMOVAL of CELL LAYERS DURING THE PISTONADDITION/REMOVAL of CELL LAYERS DURING THE PISTON
MOTIONMOTION
Correct estimation of the combustion and spray processes Correct estimation of the combustion and spray processes
if the fluid motion and turbulence distribution at IVC are if the fluid motion and turbulence distribution at IVC are
correctly predicted.correctly predicted.
VALVE ACTIONVALVE ACTION
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
DEVELOPMENT: ENGINE MESHDEVELOPMENT: ENGINE MESH
Layer AdditionLayer Addition--Removal (Removal (layerAdditionRemovallayerAdditionRemoval))
MESH MODIFIERS (MESH MODIFIERS (src/dynamicMeshsrc/dynamicMesh))
ALLOW TOPOLOGICAL CHANGES TO THE MESHALLOW TOPOLOGICAL CHANGES TO THE MESH
Add/Remove Cells/Faces/PointsAdd/Remove Cells/Faces/Points
Attach/detach boundary (Attach/detach boundary (attachDetachattachDetach))
Sliding Interface (Sliding Interface (slidingInterfaceslidingInterface))
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
DEVELOPMENT: ENGINE MESHDEVELOPMENT: ENGINE MESH
MESH MOTION (MESH MOTION (src/dynamicMesh/motionSolversrc/dynamicMesh/motionSolver))
The point motion is specified by an FEM solver. The point motion is specified by an FEM solver.
Boundary condition for the points is assigned and Boundary condition for the points is assigned and
the motionthe motion--diffusion equation is solved:diffusion equation is solved:
02 =∇ Mmotion
rµ
µµµµµµµµmotionmotion : motion diffusion: motion diffusion
M M : motion points field: motion points field
0=Mr
pUMrr
=SIMPLE DEFORMATION SIMPLE DEFORMATION
OF A 2D SQUARE BOXOF A 2D SQUARE BOX
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
DEVELOPMENT: ENGINE MESHDEVELOPMENT: ENGINE MESH
MESH MOTION ALGORITHMMESH MOTION ALGORITHM
ATTACH THE ATTACH THE
SLIDING INTERFACESLIDING INTERFACE
DETACH THE DETACH THE
SLIDING INTERFACESSLIDING INTERFACES
PERFORM PERFORM
LAYER ACTION, LAYER ACTION,
SOLVE FOR MOTION SOLVE FOR MOTION
AND MOVE POINTSAND MOVE POINTS
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
DEVELOPMENT: ENGINE MESHDEVELOPMENT: ENGINE MESH
LAYER ADDITION/REMOVAL ON THE PISTON SURFACELAYER ADDITION/REMOVAL ON THE PISTON SURFACE
TWO STROKE ENGINESTWO STROKE ENGINES
SLIDING INTERFACE TO SIMULATE PISTON MOTION SLIDING INTERFACE TO SIMULATE PISTON MOTION
TROUGH SCAVENGING PORTSTROUGH SCAVENGING PORTS
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
DEVELOPMENT: ENGINE MESHDEVELOPMENT: ENGINE MESH
FOUR STROKE ENGINES: MESH SETUPFOUR STROKE ENGINES: MESH SETUP
pistonpiston
valveStemvalveStem
valveTopvalveTop
valveBottomvalveBottom
valveCurtainPortvalveCurtainPort
valveCurtainCylvalveCurtainCyl
Layer A/RLayer A/R
Layer A/RLayer A/R
Layer A/RLayer A/R
Master patch of Master patch of
the the slidingInterfaceslidingInterfaceSlave patch of Slave patch of
the the slidingInterfaceslidingInterface
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
FOUR STROKE ENGINES: FOUR STROKE ENGINES:
VALVE CLOSURE, ATTACH/DETACH BOUNDARYVALVE CLOSURE, ATTACH/DETACH BOUNDARY
DEVELOPMENT: ENGINE MESHDEVELOPMENT: ENGINE MESH
The valve is closed when its lift is lower than a certain valueThe valve is closed when its lift is lower than a certain value
The valve closure is simulated using the The valve closure is simulated using the attachDetachattachDetach meshmesh
modifiermodifier
valveDetachInPortvalveDetachInPort
valveDetachInCylvalveDetachInCyl
When the valve opens the boundaries are reWhen the valve opens the boundaries are re--attachedattached
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
DEVELOPMENT: ENGINE MESHDEVELOPMENT: ENGINE MESH
FOUR STROKE ENGINES: FOUR STROKE ENGINES:
Mesh motion MOVIE. Section of a 3D engine withMesh motion MOVIE. Section of a 3D engine with
vertical valvesvertical valves
Layer addition/removalLayer addition/removal
on the on the pistonpiston patchpatch
Layer Layer
addition/removaladdition/removal
on the on the valveTopvalveTop andand
valveBottomvalveBottom patchespatches
slidingInterfaceslidingInterface
continuoslycontinuosly
attached andattached and
detacheddetached
Switching Switching
beetweenbeetween
deformation deformation
and layeringand layering
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
TESTING: TESTING: icoTopoFoamEngineicoTopoFoamEngine
•• INCOMPRESSIBLE SOLVERINCOMPRESSIBLE SOLVER
oo PISO algorithm for pressure/velocity couplingPISO algorithm for pressure/velocity coupling
oo Testing mesh motionTesting mesh motion
oo Testing fields mappingTesting fields mapping
oo Testing solution of equations with Testing solution of equations with
disappearing/appearing cellsdisappearing/appearing cells
FOURFOUR--STROKE ENGINE STROKE ENGINE
TEST CASETEST CASETWOTWO--STROKE ENGINE STROKE ENGINE
TEST CASETEST CASE
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
FOUR STROKE ENGINE RESULTSFOUR STROKE ENGINE RESULTS
EXHAUST STROKEEXHAUST STROKE
168 CAD168 CAD 243 CAD243 CAD 293 CAD293 CAD 318 CAD318 CAD
Velocity and pressure fieldsVelocity and pressure fields
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
FOUR STROKE ENGINE RESULTSFOUR STROKE ENGINE RESULTS
INTAKE STROKEINTAKE STROKE
Velocity and pressure fieldsVelocity and pressure fields
358 CAD358 CAD 383 CAD383 CAD 393 CAD393 CAD 423 CAD423 CAD
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
FOUR STROKE ENGINE RESULTSFOUR STROKE ENGINE RESULTS
MASS CONSERVATION CHECKMASS CONSERVATION CHECK
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
TWO STROKE ENGINE RESULTSTWO STROKE ENGINE RESULTS
SCAVENGING PHASE, 320 CADSCAVENGING PHASE, 320 CAD
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
FUTURE DEVELOPMENTSFUTURE DEVELOPMENTS
••ENGINE MESHENGINE MESH
oo Compressible solverCompressible solver
oo Turbulence, spray and combustionTurbulence, spray and combustion
oo Angled valvesAngled valves
oo Combination of valves + scavenging portsCombination of valves + scavenging ports
••COMBUSTIONCOMBUSTION
oo Developing a C++ implementation of the Developing a C++ implementation of the
Pope’s “In Situ Adaptive Chemistry Tabulation” Pope’s “In Situ Adaptive Chemistry Tabulation”
(ISAT) to reduce computational time when (ISAT) to reduce computational time when
detailed chemistry is used.detailed chemistry is used.
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
CONTACTSCONTACTS
TOMMASO LUCCHINITOMMASO LUCCHINI
DipartimentoDipartimento didi EnergeticaEnergetica
PolitecnicoPolitecnico didi MilanoMilano
Via la Via la MasaMasa, 34, 34
20185 20185 MilanoMilano
ITALYITALY
ee--mail: mail: tommaso.lucchini@polimi.ittommaso.lucchini@polimi.it
Web site: Web site: www.engines.polimi.itwww.engines.polimi.it
TommasoTommaso LucchiniLucchini: “Internal Combustion Engine Simulation in : “Internal Combustion Engine Simulation in OpenFOAMOpenFOAM”, 01”, 01--2828--20062006
ACKNOWLEDGEMENTSACKNOWLEDGEMENTS
I am very grateful to the people who introduced me to the I am very grateful to the people who introduced me to the
OpenFOAMOpenFOAM world….world….
GianlucaGianluca D’ErricoD’Errico
HrvojeHrvoje JasakJasak
GianlucaGianluca MontenegroMontenegro
NiklasNiklas NordinNordin
Henry WellerHenry Weller
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