CFD modeling of IC engines: Research work at Politecnico di ...CFD Modeling of RDE Cycle is...

GROUPPOLITECNICO DI MILANOGROUPPOLITECNICO DI MILANO

Internal Combustion Engine GroupDepartment of Energy, Politecnico di Milano

CFD modeling of IC engines: Research work at Politecnico di Milano


StaffAngelo Onorati, Full ProfessorGianluca D’Errico, Full Professor Gianluca Montenegro, Associate ProfessorTommaso Lucchini, Associate ProfessorAugusto Della Torre, Assistant professorTarcisio Cerri, Assistant professor

Post-doc/MSc researchersLorenzo Sforza, post-doc researcherGiorgio D’Antonio, MSc researcherFilippo Pavirani, MSc researcherAndrea Marinoni, MSc researcher

PhD students Davide ParediGiovanni GianettiMatteo Tamborski

Antonello NappiQiyan Zhou

Visiting PhDAalto, Sidney, KTH, Chalmers, Freiberg, Valencia, etc.,

The Internal Combustion Engine Group

MSc thesis20-25 per year


CFD for IC Engines: why OpenFOAM?

Requirements

Implementation of new models• Research on fundamental topics• Extensive validation using

different type of data (engine, vessels)

Fully integrated methodologies

Massive application in researchand industrial projects

OpenFOAM is the solution• Free and opensource

• Many pre-implementedcapabilities: meshing, numerics, models

• Different available versions but verycompatible

• Perfect basis to develop ownlibraries and solvers for complexproblems


In-cylinder flows


In-cylinder simulations workflow

Automaticmesh

generation

Combustionmodels

Meshhandling

Engine CAD data

Cold flow

Spray

Gas injection


Spark-ignition engines: mesh generation and handling

Initial mesh at Crank angle θ0

Move mesh for ∆θ

Mesh quality and duration

satisfied?

θcurr = θ0

θcurr = θcurr + ∆θ

YES

NO

Move surface geometry to current crank

angle θcurr

θcurr = θend ?

End of meshing

NO

YES

Generate a new mesh with

snappyHexMesh

θ0 = θcurr

Input engine geometry data:• STL geometry• stroke, bore, connecting

rod length• valve lift curves• rounds per minute

Input data Automatic meshing Mesh-motion


Spark-ignition engines: mesh generation and handlingMesh motion and full-cycle simulation


SI engines: direct-injectionNatural gas / hydrogen Liquid fuels

SANDIA H2 engine

Velocityfield at 100 CAD BTDC

Equivalence ratio distribution

ECN spray G

Spray penetration

Validationwith PIV

data15 m

m


Spark-ignition engines: EU project HDGas• Purpose: development of dedicated SI, natural gas engines for heavy duty • OpenFOAM and LibICE used for design of combustion chamber and analysis of fuel-air mixing

Intake port design Charge motions analysis

Dischargecoefficient (Cd)

Tumble ratio (TR)

Disc

harg

eco

effic

ient

(Cd)

Tum

ble

ratio

(TR)

Lift/diameter ratio (L/dv)

Layout A Layout B Layout C Tumble ratio

Turbulentkinetic energy

1000 rpm

1200 rpm

Acknowledments: S. Golini, N. Rapetto (FPT Industrial)


Spark-ignition engines: EU project HDGasSimulation of the fuel-air mixing process

Acknowledments: S. Golini, N. Rapetto (FPT Industrial)

Contours of equivalence ratio

Rela

tive

air/

fuel

ratio

λCrank angle [deg]

Equivalenceratio distribution atspark-timing

Hom

ogen

eity

inde

x[-

]

Cylin

derm

ass [

kg]

Dist

ribut

ion

[-]

Crank angle [deg]

Relative air/fuel ratio λ


Spark-ignition engines: EU project UPGRADE• Purpose: development of a new generation of GDI Engines with high efficiency and low-soot• OpenFOAM and LibICE used to perform full-cycle simulations (gas exchange, fuel-air mixing and

combustion) in both production and optical engines.

Acknowledments: A. Gerini, S. Zandiri, F. Perna (CRF)

Turbocharged engine with Multi-air® technology Full-cycle simulations (gas exchange only)

2000 rpm, bmep = 2 bar2000 rpm, bmep = 4 bar

1500 rpm, full load2500 rpm, bmep = 13 bar

Crank angle [deg]

Cylin

derp

ress

ure

[bar

]


Spark-ignition engines: EU project UPGRADE

Acknowledments: A. Gerini, S. Zandiri, F. Perna (CRF)

Simulation of the fuel-air mixing process with wall-film

CRF Engine IFPEN Engine

Exp. data courtesyof IFPEN (Dr. M. Bardi)


Spark-ignition engines: combustion modelingComprehensive approach for spark-ignition combustion

C3H8-N2

C2H2-N2

C3H8-BG

C2H2-BG


Spark-ignition engines: combustion modelingComprehensive approach for spark-ignition combustion – CHIBA VESSEL

Current

Voltage

Cold-flow initialization Combustion simulation

Acknowledments: T. Shiraishi, T. Hori(Nissan); prof. Moriyoshi (Chiba University)

Cur

rent

Volta

ge

time [ms]

time [ms]


Spark-ignition engines: combustion modelingGM pancake engine

Computational mesh flame propagation

Validation (cyl. press and cumulative heat release)

Side-chamber engine (Herweg and Maly)

Peripheral ignition Central ignition


Diesel engines: mesh generation and handling

a) Main engine data b) Spray oriented block mesh

c) Combustion chamber points fit

Mesh handling

d) Spray-oriented mesh

Bowl #1 Bowl #2 Bowl #3

Bowl #4 Bowl #5 Bowl #6

From CAD to SIMULATION: 10 minutes

Automatic mesh generation

Dynamic layering


Diesel engines: spray modelingTUE Vessel

(a) (

Pinj[MPa]

ρamb[kg/m3]

ANR 150 22

C1 80 40

C2 150 40

• dinj = 205 µm• 3D mesh• Huh-Gosman + Pilch

Erdman

Acknowledgments: B. Somers, N. Maes (TUE), G. Hardy (FPT)

Liquid+vapor penetration


Diesel engines: combustion modelingRIF: Representative interactive flamelet model

( )xH ~

pjst ,~,χ

( )xT ~ ( ) ( )xYhxH ii ∑ ⋅= ~~

CFD domain

( ) ( )xZxZ 2'',~

Flamelets( )tZY ij ,~,

( ) ( ) ηηη dpYMYZ

ij

N

jji

f

∫∑==

⋅=1

0,

1

~~

jM

• Flamelet equations solved in the mixture fractionspace (regionModel)

• Direct-integration of chemistry in Z-space and integration of β-pdf to get the composition in any cell.

Tabulated kinetics

Kineticmechanism

Conditions• p, Tu, φ, EGR

Homogeneous, constant-

pressure reactorsimulations

HR Table- Composition (virtual

species)- Output species- Progress variable

reaction rate

From HR tabulation to more complex flame structures and combustion models for different conditions:

- TWM : well mixed (no turbulence chemistry interaction)

- TPPDF : presumed pdf

- TRIF : RIF model with tabulated reaction rate (from HR)

- TFPV : flamelet progress variable model. Reaction ratesbased on diffusion flame calculations performed with the TRIF model.


Diesel engines: RIF modelbm

ep/b

mep

max

0

1

600 2200Engine speed [rpm]

(a)

FPT C11 engine

Acknowledgments: G. Hardy (FPT)

Heavy-duty engine for road transportation

• 14 operating points selected at differentloads and speeds

• Spray model constants tuned usingresults from TUE vessel simulations

Spray-oriented grid


Diesel engines: RIF modelFPT C11 engineHeavy-duty engine for road transportation: engine performance prediction (pressure and work)

0

50

100

150

200

250

0 50 100 150 200 250

P max

,cal

c [b

ar]

Pmax,exp [bar]

0

0.2

0.4

0.6

0.8

1

1.2

0 0.5 1g.

i. w

ork c

alc

/ g.

i. w

ork m

ax,e

xpg.i. workexp / g.i. workmax,exp

(b)


Diesel engines: RIF modelFPT C11 engineHeavy-duty engine for road transportation: pollutants prediction (NOx and CO)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 0.5 1 1.5CO

calc

/ CO

max

EXP

COEXP/ COmax EXP

0

0.2

0.4

0.6

0.8

1

1.2

0 0.5 1 1.5

NOx,

calc

/ NO

x,m

ax E

XP

NOx EXP/ NOx,max EXP

Model 1Model 2

(a)


Diesel engines: tabulated kinetics

13

4

5

6

7

8

2

Name [rpm] load λ

1 HEGR 1400 12% 2.7

2 1400 50% 1.4

3 A25 2000 25% 2.1

4 A75 2000 75% 1.3

5 B50 2750 50% 1.4

6 B100 2750 100% 1.3

7 C40 3500 40% 2.3

8 C100 3500 100% 1.5

Compre ratio 18IVC -145 degEVO 110 deg

Nozz hole dia

Homo

FPT F1C engineLight-duty engine for road transportation

Temperature [K] 600 – 1300

Pressure [bar] 30 - 200

Equivalence ratio 0 – 3

Mixture fractionsegregation 0.0 - 1.0

Scalar dissipation rate χst [1/s] 0 – 55

• TPPDF, TRIF, TFPV TCI included

Table discretization



• B50• 50% load• 3 injections• 15% EGR

0

0.3

0.6

0.9

1.2

1000 2000 3000 4000

bmep

/bm

epm

ax

Engine speed [rpm]

13

4

5

6

7

8

2

• Similar heat release rate during main combustion

• Ignition delay: TFPV ignites earlier

than TRIF and TPPF during second and main injection events.



• All the models are able to capture in-cylinder pressure peak and NOx• CPU time: 15 hours on a 8 core machine for a power-cycle (dual-core, eight processor Intel

Xeon E5- 2630 v3 2.40GHz)

Exp. NOx/ NOx MAX C100 [-]

Calc

. NO

x/ NO

x M

AX C

100 [-]


Diesel engines: alternative combustion modes

Conventional Diesel combustion PCCI combustion

Temperature

Equi

vale

nce

ratio

Temperature

Equi

vale

nce

ratio


Leung-Lindsted and Jones model

Diesel engines: soot prediction

Soot distributionExperimental

Computed

Experimental

Computed

x [mm]20 25 30 35 40 45 50 55 60 65

420

-2-4

x [mm]20 25 30 35 40 45 50 55 60 65

420

-2-4

20 25 30 35 50 55 60 65

20 25 30 35 40 45 50 55 60 65

fv

fv

fv

fv

(a): O3 (b): T3

420

-2-4

420

-2-4

40 45x [mm]

x [mm]

y [m

m]

y [m

m]

y [m

m]

y [m

m]

• Two equation approach solving for 𝑓𝑓𝑣𝑣 and 𝑁𝑁𝑝𝑝using 𝐶𝐶2𝐻𝐻2 as precursor

0

10

20

30

40

50

60

0 1 2 3 4 5 6 7 8

Tota

l soo

t mas

s (µ

g)

Time ASOI [ms]

measured T3 measured O3computed T3 computed O3


After-treatment


After treatment

Engine system scale

Micro-scale Macro-scale Component scale

Overview of the physical scales of

the problem&

CFD modellingapproaches


After treatment: computational model

Fluid mesh

Solidmesh

mass heat

Bulk gas model

Near wall gasWashcoat

Substrateheat

Surface reactions

Gas reactions

Coupling between fluid and solid regions requires specificmodels (Geometry, Permeability, Heat transfer,mass transfer, reaction)

Information for the setup of the models are obtained by micro-scale simulations or experimental correlations.

Macro-scale model is defined on two overlapping fluid and solid FV meshes

Solid mesh support the modelling of different zones (gas, washcoat, solid)


After treatment: DOC simulation

Electricalheated

fluid

solid:DOC

solid:heater

MF(t)T(t)Yi(t)

DOC modelling: preliminary validation case



InletMonolith, mid position, calcOutlet, calcOutlet, exp

No Electrical HeatingTemperature at catalyst outletTsolid

Tflow

COsolid

COflow

With Electrical Heating

Tsolid

Tflow COflow

COsolid

InletMonolith, mid position, calc (----- current 1.c; - - - original 1.b)Outlet, calc (---- current 1.c; - - - original 1.b)

• Ceramic substrate (1.b)• Metallic substrate (1.c), with electrical heating Pel = 1kW

Solid

FluidInlet

Outlet

Monolith

Tem

pera

ture

[K]

Tem

pera

ture

[K]


After treatment: DOC simulationFull-scale 3D case including DOC monolith and electrical heating

t)

ut: GR

Out: SCR underfloor

eHC+

DOC

SCR

Semi-empirical model to describe electrical heatingbased on assumedtemperature distribution

Fluid

Solid: DOCSolid: eHC

• Cell agglomeration after meshing• Different maximum Courant numbers in

different zones CFD Modeling of RDE Cycle is possible!



Non-uniform heatingPel = 1 kW : 0-100 sPel = 0.5-0.2 kW : 100-300 s

Temperature CO

FluidSolid: DOC

Solid: eHC

Fluid

Solid: DOC

Solid: eHC

Non-uniformity of the heating generates hot spots earlier light-off



Time = 140 s

Non-heated DOC configuration



Time = 140 s

DOC configuration with non-uniform heating (Pel = 1 kW)


After treatment: SCR mixer optimization

Injection of gaseous NH3

Evaluation of the 𝑈𝑈𝑈𝑈(𝑁𝑁𝐻𝐻3)on the SRC inlet plane

Mixer

α

β

γ

Optimization of the mixer geometry• Variables: angles α, β, γ of the mixer blades• Function objects: ∆𝑝𝑝𝑚𝑚𝑚𝑚𝑚𝑚, 𝑈𝑈𝑈𝑈(𝑁𝑁𝐻𝐻3) 𝑆𝑆𝑆𝑆𝑆𝑆,𝑚𝑚𝑖𝑖𝑖𝑖 x 2 MF (low and high)


After treatment: optimization procedure

CFD: calculation of the «simulated» responses (50 + N samples)

Surrogated model

GA: calculation of the «approximated» responses (1000 samples)

Optimum at the Nth iteration

Err < toll

CAD: definition of the parametric geometry


After treatment: SCR mixer optimization

DOE


Conclusions on LibICE activities

OpenFOAM for IC Engine simulationsIdeal platform to develop advanced models to simulated complex problems in realgeometries including: - Turbulent and multiphase flows- Chemical reactions- Moving boundaries

OpenFOAM + LibICE: consolidated tool for engine design, optimization and analysis: - In-cylinder flows- Combustion and pollutant emissions- After-treatment devices

Next directions- Advanced combustion modes (RCCI, PCCI, dual fuel)- Flash boiling and new wall film model (Lagrangian)- Models for sophisticated after-treatment devices operating under RDE conditions.


1D simulation code: GASDYN

Developed at PoliMi duringthe last 20 years, now co-developed with Exothermia.GASDYN is also coupled tothe AXISUITE simulationcode, for the simulation ofthe complete after-treatmentsystem.



• Strong partnership between PoliMi, Exothermia andAristotle University on this research topic, for furtherdevelopments and applications of GASDYN.


User friendly and intuitive GUI:

L4 turbo-charged, natural gas SI engine with complete intake and exhaust systems.

V10 NA SI high-speed engine with Variable Intake System (VIS)



mmY ii /=

Vector of specie mass fractions

.Y

Y

1N

1

=

−

Y

ρρρρ

=

FFe

uFF

)t,x(0

Y

W

ρρ

+ρρ

=

FuFuhpFFu

uF

)(0

2

Y

WF

−

=

00dxdFp

0

)( WB

+−=

FFqq

GF

reY

WC

ρρ

ρ)(

0

)(

Reactions of species in the flow (exhaust manifold andcatalysts).

O2N2Ar CO2H2O H2CO NO C3H6C3H8...

Y=


0=++∂

∂+

∂∂ )()(

x)(

t)t,x( WCWBWFW

Conservation equations for mass, momentum and energy in 1D:


Swept volume: 4244 cm3

Max. Power: 287 kW @ 7000 rpmMax. Torque: 451 Nm @ 4500 rpm

Model application: Ferrari-Maserati V8 Engine


Volumetric Efficiency

64.00

69.00

74.00

79.00

84.00

89.00

94.00

99.00

104.00

109.00

114.00

1000 2000 3000 4000 5000 6000 7000Engine Speed [rpm]

Volu

met

ric E

ffici

ency

[%]

Experimental

Predicted

Brake Torque

150

200

250

300

350

400

450

1000 2000 3000 4000 5000 6000 7000Engine Speed [rpm]

Torq

ue [r

pm]

Experimental

Predicted


P(chemicalprobe)

Throttle valvesto actuate the VIS

P(chemicalprobe)

Throttle valvesto actuate the VIS

• 12 Cylinders, V60, 6.2 liters, Variable Intake System, intake andexhaust VVT, 650 Nm@5400 rpm, 426 kW@7500 rpm

(a)

(b)

(c)

(a)

(b)

(c)


Pressure transducer locations

cyl 1

cyl 5

cyl 2

cyl 6

cyl 4

Silencer

PT 7

PT 10

PT 5

PT 6

PT 8

PT 4

PT 1

cyl 3

Pressure transducer locations

cyl 1

cyl 5

cyl 2

cyl 6

cyl 4

Silencer

PT 7

PT 10

PT 5

PT 6

PT 8

PT 4

PT 1

cyl 3


0 90 180 270 360 450 540 630 720Crank angle [°]

0.3

0.5

0.7

0.9

1.1

1.3

1.5

1.7

1.9

Pres

sure

[bar

]

PT1 - 4500 rpm Predicted

Measured

0 90 180 270 360 450 540 630 720Crank angle [°]

0 90 180 270 360 450 540 630 720Crank angle [°]

0.3

0.5

0.7

0.9

1.1

1.3

1.5

1.7

1.9

Pres

sure

[bar

]


Measured


Measured0.3

0.5

0.7

0.9

1.1

1.3

1.5

1.7

Pres

sure

[bar

]

0 90 180 270 360 450 540 630 720Crank angle [°]


Measured

0.3

0.5

0.7

0.9

1.1

1.3

1.5

1.7

Pres

sure

[bar

]

0 90 180 270 360 450 540 630 720Crank angle [°]

0 90 180 270 360 450 540 630 720Crank angle [°]


Measured


Measured

0 90 180 270 360 450 540 630 720Crank angle [°]


Measured0.3

0.5

0.7

0.9

1.1

1.3

1.5

1.7

Pres

sure

[bar

]

0 90 180 270 360 450 540 630 720Crank angle [°]

0 90 180 270 360 450 540 630 720Crank angle [°]


Measured


Measured0.3

0.5

0.7

0.9

1.1

1.3

1.5

1.7

Pres

sure

[bar

]

0 90 180 270 360 450 540 630 720Crank angle [°]

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

Pres

sure

[bar

]


Measured

0 90 180 270 360 450 540 630 720Crank angle [°]

0 90 180 270 360 450 540 630 720Crank angle [°]

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

Pres

sure

[bar

]


Measured


Measured

(a)

(c)

(b)

(d)

0 90 180 270 360 450 540 630 720Crank angle [°]

0.3

0.5

0.7

0.9

1.1

1.3

1.5

1.7

1.9

Pres

sure

[bar

]


Measured

0 90 180 270 360 450 540 630 720Crank angle [°]

0 90 180 270 360 450 540 630 720Crank angle [°]

0.3

0.5

0.7

0.9

1.1

1.3

1.5

1.7

1.9

Pres

sure

[bar

]


Measured


Measured0.3

0.5

0.7

0.9

1.1

1.3

1.5

1.7

Pres

sure

[bar

]

0 90 180 270 360 450 540 630 720Crank angle [°]


Measured

0.3

0.5

0.7

0.9

1.1

1.3

1.5

1.7

Pres

sure

[bar

]

0 90 180 270 360 450 540 630 720Crank angle [°]

0 90 180 270 360 450 540 630 720Crank angle [°]


Measured


Measured

0 90 180 270 360 450 540 630 720Crank angle [°]


Measured0.3

0.5

0.7

0.9

1.1

1.3

1.5

1.7

Pres

sure

[bar

]

0 90 180 270 360 450 540 630 720Crank angle [°]

0 90 180 270 360 450 540 630 720Crank angle [°]


Measured


Measured0.3

0.5

0.7

0.9

1.1

1.3

1.5

1.7

Pres

sure

[bar

]

0 90 180 270 360 450 540 630 720Crank angle [°]

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

Pres

sure

[bar

]


Measured

0 90 180 270 360 450 540 630 720Crank angle [°]

0 90 180 270 360 450 540 630 720Crank angle [°]

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

Pres

sure

[bar

]


Measured


Measured

(a)

(c)

(b)

(d)

Pressure pulses in the exhaust system



Transport of reacting chemical species

10 species (or more) can be transported along the duct system with eventual reactions (unsteady reacting flows)(e.g. O2, N2, Ar, CO2, H2O, H2, CO, NO, C3H6, C3H8)

0.750

0.800

0.850

0.900

0.950

1.000

1.050

1.100

1.150

1.200

0 90 180 270 360 450 540 630 720Crank angle [°]

Pres

sure

[bar

]

Pressure pulse downstream of main catalystEngine speed= 3400 rpm, full load

Predicted, perfect gasPredicted, species transport

Experimental

Secondary air injection(reduce cat. light-off time –

speed up EAT system warm-up)



Multiple Double-Wiebe 3-Zone Combustion ModelGasdyn MDW3Z Model

• Combustion model developed by ICEgroupo Designed to handle modern multi-pulse injectiono Combustion chamber subdivided into three zones:

o Fresh chargeo Fuel (vaporized)o Exhaust gas

• Combustion rate imposed by means of multiple double-Wiebe law taking account the in-cylinder conditionso Pressure and temperatureo Mixture composition (fresh charge, fuel, EGR)o Injection timings

• Fast run time• Injection

o Each discrete injection event is defined as a pulseo Up to 4 number of pulses

1st Wiebe function (premixed combustion)

2nd Wiebe function (diffusive combustion)

• Double Wiebe functiono Each pulse burns with a rate defined by the following

expression

• Ignitiono Ignition delay calculated as

• Ignition occurs when

• NOxo Extended Zeldovich mechanism

• COo Equilibrium approach

• Sooto Semi-empirical Hiroyasu model predicts the soot

formation rateo Semi-empirical Nagle Strickland predicts the

oxidation soot step

• Combustion modelo HRR calculated separately for each pulseo Different Wiebe coefficients for each pulseo Wiebe coefficients parametrized as a function

of in-cylinder residuals

-30 -15 0 15 30 45 60

Rate

of m

ass f

ract

ion

burn

ed

Crank angle [deg]

Rate pilot1Rate pilot2Rate mainBurned mass rateInjection pilot1Injection pilot2Injection main


Case Study: Four Cylinders, Turbo-Charged, DI Diesel EngineGasdyn MDW3Z Model

• Operating point #3 o 25% load, 2000 rpm, three injections: 2 pil. + main

0.0

10.0

20.0

30.0

40.0

50.0

0 1 2 3 4 5 6 7 8 9 10

EGR [%]

measured computed

0

1

2

3

4

5

1 2 3 4 5 6 7 8 9

Pulses [-]

tot. pulses pilots

0

0.5

1

1.5

2

1 2 3 4 5 6 7 8 9

BMEP [MPa]

measured computed

00.20.40.60.8

11.21.4

0 1 2 3 4 5 6 7 8 9 10

NOx/NOx_max [-]

measured computed

0

200

400

600

800

1000

0 1 2 3 4 5 6 7 8 9 10

CO [ppm]

measured computed

00.20.40.60.8

11.21.4

0 1 2 3 4 5 6 7 8 9 10

soot/soot_max [-]

measured computed

• Operating point #9 o 100% load, 3500 rpm, only main injection

0.0

20.0

40.0

60.0

80.0

-180.0 -120.0 -60.0 0.0 60.0 120.0 180.0

Cylinder pressure [bar] vs. crank angle [deg]

measuredcomputed

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

-180.0 -120.0 -60.0 0.0 60.0 120.0 180.0

Cylinder pressure [bar] vs. crank angle [deg]

measuredcomputed

0.010.020.030.040.050.060.070.080.090.0

-30.0 -15.0 0.0 15.0 30.0 45.0 60.0 75.0 90.0

HRR [J/deg] vs. crank angle [°]

measuredcomputed

Operating points used to tune the combustion model

0.0

20.0

40.0

60.0

80.0

100.0

120.0

-30.0 -15.0 0.0 15.0 30.0 45.0 60.0 75.0 90.0

HRR [J/deg] vs crank angle [deg]

measuredcomputed


Unsteady flows in intake and exhaust systems: 1D-3D coupling

Coupled 1D-3D simulations


P2I_HF - downstream of the intercooler

0.98

0.99

1

1.01

1.02

1.03

1.04

1.05

1.06

1.07

0 60 120 180 240 300 360 420 480 540 600 660 720Crank angle [°]

Pres

sure

[bar

]

MeasuredComputed 1D-3D

(a) - 1500 rpm


2.2

2.3

2.4

2.5

2.6

0 60 120 180 240 300 360 420 480 540 600 660 720Crank angle [°]

Pres

sure

[bar

]


(c) - 3000 rpm(b)


0.98

0.99

1

1.01

1.02

1.03

1.04

1.05

1.06

1.07

0 60 120 180 240 300 360 420 480 540 600 660 720Crank angle [°]

Pres

sure

[bar

]


(a) - 1500 rpm


2.2

2.3

2.4

2.5

2.6

0 60 120 180 240 300 360 420 480 540 600 660 720Crank angle [°]

Pres

sure

[bar

]


(c) - 3000 rpm(b)

P2I_HF - upstream of the turbine

1

1.1

1.2

1.3

1.4

0 60 120 180 240 300 360 420 480 540 600 660 720Crank angle [°]

Pres

sure

[bar

]


(b) - 1500 rpm

P1T_HF - upstream of the turbine

2

2.2

2.4

2.6

2.8

3

3.2

3.4

3.6

0 60 120 180 240 300 360 420 480 540 600 660 720Crank angle [°]

Pres

sure

[bar

]


(d) - 3000 rpm(b)

(a)

P2I_HF - upstream of the turbine

1

1.1

1.2

1.3

1.4

0 60 120 180 240 300 360 420 480 540 600 660 720Crank angle [°]

Pres

sure

[bar

]


(b) - 1500 rpm

P1T_HF - upstream of the turbine

2

2.2

2.4

2.6

2.8

3

3.2

3.4

3.6

0 60 120 180 240 300 360 420 480 540 600 660 720Crank angle [°]

Pres

sure

[bar

]


(d) - 3000 rpm(b)

(a)

1500 rpm – 40 Nm, 3000 rpm – 220 Nm

Pressure wave validation, 1D-3D simulations

Pressure, downstream of intercooler Pressure, upstream of turbine

Pressure, downstream of intercooler Pressure, upstream of turbine


1D code GASDYN coupled to OpenFOAM: intake air-box, 3D domain

Fully tetrahedral mesh, 18000 cells

1D-3D simulation of an Aprilia V4 engine


•A quasi-3D method (3Dcell approach) has been developed and validated as acompromise between the time-demanding 3D CFD analysis and the fast 1D approach,resorting to a 3D grid of 0D elements (coarse grid: 1-2 cm).

3Dcell approach

• Unviscous gas: Euler equations


90° T junction: simulation (coarse grid)

90° T junction: simulation (fine grid)

3Dcell approach


Simple expansion chamber:1D model vs 3D cell prediction

Experimental

1D, Gasdyn


1D-quasi3D integrated model


Air-box and silencer modeling

CFD modeling of IC engines: Research work at Politecnico di ...CFD Modeling of RDE Cycle is...

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