Transcript Gasoline & Diesel Engineering Fluid Simulation Tools Ricardo Japan TSA Visits November 2005 RD.05/406501.1 © Ricardo plc 2005

Gasoline & Diesel Engineering
Fluid Simulation Tools
Ricardo Japan TSA Visits
November 2005
RD.05/406501.1
© Ricardo plc 2005
Agenda
 Background
 Combustion System Simulation
 Intake, Exhaust and Aftertreatment System
 Engine Thermal Modelling
© Ricardo plc 2005
 Crankcase Breathing
 Vehicle Simulation
RD05/406501.1 2
Agenda
 Background
 Combustion System Simulation
 Intake, Exhaust and Aftertreatment System
 Engine Thermal Modelling
 Crankcase Breathing
© Ricardo plc 2005
 Vehicle Simulation
RD05/406501.1 3
Background
 Simulation technology has ability to reduce product development cycle significantly
 Principal requirements are:
– Robust analysis methodology capable of capturing major physical parameters
through direct modelling or correlated database information
– Rapid analysis toolset to provide engineering direction for component / system /
powertrain development
© Ricardo plc 2005
– Validated modelling approach allowing predictive application to engineering projects
Presentation will outline fluid simulation application processes to allow
technologies application on powertrain development projects leading to
reduced product development cycles
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Agenda
 Background
 Combustion System Simulation
 Intake, Exhaust and Aftertreatment System
 Engine Thermal Modelling
 Crankcase Breathing
© Ricardo plc 2005
 Vehicle Simulation
RD05/406501.1 5
Combustion System Simulation
 Combustion system tools and techniques research forms primary stages in application
of simulation to combustion system development
 Tools and techniques allow predictive application of some modelling technology to
development
Experimental techniques to measure fundamental physical
processes for basic validation of CFD codes
Ongoing detailed tools and techniques programme measuring gasoline
and diesel fuel spray behaviour under realistic engine operating conditions
© Ricardo plc 2005
Development of modelling processes following fundamental validation for application to
engineering programmes
Continual process of methodology evolution and development with validation against test
programmes where applicable
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Fuel Spray Measurement and Validation
 Gasoline spray and mixture measurement
– Quiescent fuel spray characterisation
– MIE scattering measurements in motored
engine
• homogeneous operation
• stratified operation
– Quantitative LIF measurement
Mie Camera
Optical Engine
Laser Sheet
Viewing Annulus
LIF Camera
© Ricardo plc 2005
 Diesel spray and mixture measurement
– Quiescent spray bomb characterisation
– Ricardo Diesel spray rig
• Provides cylinder
conditions
close to engine
cylinder conditions
 Validation techniques
applied to VECTIS
and Star CD
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Combustion System
Gasoline Engine Application Process
 Gasoline combustion system design support
© Ricardo plc 2005
 3D CFD simulation applications include
– PFI and GDI combustion system development
– Cold start mixture preparation simulation
– Combustion and emissions prediction for
conventional or HCCI operation
– Knock prediction development
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Gasoline Engine Application Process
 Principal issues for simulation focus
– Geometry definition
• Model exactly what will or has been tested
– Spray modelling
• Injector characterisation and spray match
– Wall film prediction
© Ricardo plc 2005
– Boundary conditions
• Flow conditions (high speed pressure data from 1D / test)
• Thermal boundary conditions
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Combustion System
Case Study – Gasoline HCCI
 Ricardo Gasoline Engine HCCI combustion Research
Two-stroke engines
Conventional
engines
© Ricardo plc 2005
Optical
engines
Modelling tools
WAVE
1-D
Four-stroke engines
VECTIS
3-D
Conventional
engines
Optical
engines
Combustion system design
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Combustion System
Case Study – Gasoline HCCI
 Uncertainties encountered in the modeling study of HCCI engine combustion
– Charge inhomogeneity
• Thermal inhomogeneity
• Composition inhomogeneity
– Trapped conditions
• High percentage of trapped residuals, difficult to measure experimentally
© Ricardo plc 2005
 Simulation strategy
– Full 3-D CFD simulation to cover all processes included in the engine cycle
– Multi-cycle simulation approach to eliminate the uncertainties regarding trapped
conditions
– Compact ignition and combustion models for computational efficiency
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Combustion System
Case Study - 2-stroke Gasoline HCCI
 Engine Configuration
– Upright intake ports
– 4 poppet valves
– Pent roof combustion chamber
– Flat piston
– Swept volume 325cc
– Compression ratio 9.0
– Loop scavenging
TDC
 Valve and injection timing
EVO
© Ricardo plc 2005
IVC
CA
EVC
IVO
SOI
BDC
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Combustion System
Case Study - 2-stroke - Simulation Cases
Case num ber
A
B
C
D
E n g in e s p e e d [re v /m in ]
2250
2753
3255
3258
IM E P [b a r]
1 .9 6 7
2 .6 1
3 .8 3 4
1 .5 6 6
O v e ra ll A F R
1 9 .3 9
1 8 .6 7
1 9 .1 7
1 9 .1 5
4.5
IMEP [bar]
4.0
C
3.5
HCCI Operation
3.0
B
2.5
A
2.0
D
© Ricardo plc 2005
1.5
1.0
1000
1500
2000
2500
Engine Speed [rev/min]
3000
3500
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Combustion System
Case Study – 2-stroke – Simulation Approach
 Start position after the end of combustion but before exhaust valve opening
– Initial cylinder pressure from experimental measurement
– other initial conditions estimated
 Pressure boundary conditions applied at the intake port entrance and exhaust port exit
– Boundary pressures taken from the recorded dynamic pressures from engine test
© Ricardo plc 2005
 Multi-cycle combustion simulation performed until a cyclically-converged solution
obtained
– Ignition control variable and combustion species re-initialized once every cycle
 Ignition model scaling coefficient Cig tuned in the first case, then kept unchanged for
the remaining simulations
– No tuning of combustion model performed
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Combustion System
© Ricardo plc 2005
Case Study – 2-stroke – Simulation Results: In-cylinder Processes
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Combustion System
Case Study – 2-stroke – Simulation Results: Charge Inhomogeneity
 Under 2-stroke operation the in-cylinder charge inhomogeneity can be significant
 A quantitative description of inhomogeneity can be provided by using the distribution
density function
– DDF - a probability density function of the representative variables
Distribution density function
25.0
310deg
320deg
330deg
340deg
350deg
20.0
15.0
CA
CA
CA
CA
CA
10.0
5.0
0.0
0.30
0.35
0.40
0.45
0.50
0.55
0.60
0.65
0.70
© Ricardo plc 2005
Residual mass fraction
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Combustion System
Case Study – 2-stroke – Simulation Results: NOx Emission
 NOx prediction based on the extended Zeldovich mechanism, considering thermal
NO only
 NOx volume fraction monitored at the far end of exhaust port and averaged over a
cycle
Case number
A
B
C
D
Measured NOx [ppm]
13.1
164.6
520.6
34.0
Predicted NOx [ppm]
0.046
223.2
715.9
53.6
 Correct trend and order of magnitude
 A general over-prediction of 30%
© Ricardo plc 2005
 Under-prediction in Case A may be attributed to neglecting prompt NOx
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Combustion System
Diesel Engine Application Process
 HSDI combustion system development
simulation support
– 1D performance simulation
• Advanced air handling and EGR system
development
• Advanced aftertreatment modelling
© Ricardo plc 2005
– 3D CFD simulation
• Fuel – air mixing and combustion for bowl
design and swirl development
• Combustion prediction for emissions
modelling
– Intake port development
• Steady state air motion development
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Combustion System
Diesel Engine Application Process
 Pragmatic approach for rapid application to diesel combustion
system simulation
– 3D CFD analysis for base system definition
• Rapid assessment of critical hardware
– Swirl level, chamber design
• Specification of initial system for engine demonstration
– FIE requirements
– Air motion requirements
• Full load/part load compromise
– Compression ratio selection
– Combustion chamber geometry definition
© Ricardo plc 2005
• Combustion modelling for emissions prediction
– Engine testing for detailed development using DoE based
calibration
• Tuning of protrusion and nozzle flow
• Engine calibration
– EGR rate, injection timing, injection specification
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Diesel Engine Application Process
 Combustion system issues for accurate simulation
– Geometry definition
• Compression ratio volume match
• Trapped mass
– Imposition of boundary conditions for closed cycle simulation
– Multiple full cycle simulations to converge trapped conditions
– Coupled 1D/3D in-cylinder for complete engine system modelling
© Ricardo plc 2005
– Spray modelling
• Fundamental spray match has developed accurate process for
modelling
– Combustion modelling
• Application of RTZF model in VECTIS
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Combustion System
Case Study – Diesel Fuel/Air Mixing for High Performance
Methodology – Overall Approach
 Geometry assembly
– Closed volume at IVC
© Ricardo plc 2005
 Mesh generation
 Analysis
– Fuel/air mixing only
– Analysis starts at IVC
• Post-processing
• Results analysis and engineering review is always critical
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Combustion System
Case Study – Diesel Fuel/Air Mixing for High Performance
© Ricardo plc 2005
Methodology - Fuel Spray Modelling
 Multi-dimensional modelling of in-cylinder flow and spray
– Gas phase
• Equations solved in 3-D, Cartesian co-ordinates for conservation of mass,
momentum, energy and k- turbulence model
– Liquid phase
• Discrete droplet model
• Lagrangian tracking of droplet parcels and heat and mass transfer through mesh
for PDE solution
• Sub-models
– Huh-Gosman atomisation model
– Secondary droplet break-up
• Reitz-Diwakar
• Liu-Mather-Reitz
• Patterson-Reitz
– Droplet-turbulence interactions
– Droplet-droplet interactions
• Validated against diesel spray rig
RD05/406501.1 22
Combustion System
Case Study – Diesel Fuel/Air Mixing for High Performance
Methodology – Results Analysis
 Velocity and fuel vapour field plots require experience and time to interpret
– Move towards quantitative representations of data though development of
objective measures to quantify changes
– Criteria developed and measurable parameters correlated against engine data
© Ricardo plc 2005
 Assessment methodology for fuel/air mixing
– 2 level zone analysis
• Combustion chamber split into distinct zones
• Equivalence ratio and fuel vapour distribution within each zone is assessed
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Combustion System
Case Study – Diesel Fuel/Air Mixing for High Performance
 Combustion system demonstrator program requiring “right first time” development
approach
 Program targets
– Rated power > 60 kW/l
– Peak torque > 200 Nm/l
– EURO 4 emissions level
© Ricardo plc 2005
 Results shown for initial nozzle specification study comparing 6 hole against 7 hole for
the same flow specification
RD05/406501.1 24
Combustion System
Case Study – Diesel Fuel/Air Mixing for High Performance
Methodology – Results Overview
6 v s 7 H o le N o z z le S tu d y - F a v o u r a b le Zo n e
F u e l/Air M ix tu re M a s s (m g )
300
250
200
6 hole nozzle shows
improved mixing within
favourable zone
Increased combustible
mixture present
150
100
50
0
© Ricardo plc 2005
340
350
360
370
380
390
400
C ra n k a n g le (d e g )
C as e1l_S toic h
C as e1l_R ic h
C as e1d_S toic h
C as e1d_R ic h
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Combustion System
Case Study – Diesel Fuel/Air Mixing for High Performance
Methodology – Results Overview
6 v s 7 H o le N o z z le S tu d y - U n fa v o u r a b le Zo n e
100
F u e l/Air M ix tu re M a s s (m g )
90
80
70
60
50
40
30
20
10
0
© Ricardo plc 2005
340
350
360
370
380
390
400
7 hole nozzle shows
worse mixture
retention - Increased
combustible and rich
mixture close to bore
wall
C ra n k a n g le (d e g )
C as e1l_S toic h
C as e1l_R ic h
C as e1d_S toic h
C as e1d_R ic h
RD05/406501.1 26
Combustion System
Case Study – Diesel Fuel/Air Mixing for High Performance
Methodology – Results Overview
6 v s 7 H o le N o z z le S tu d y - Zo n e D
200
F u e l/Air M ix tu re M a s s (m g )
180
160
140
120
100
7 hole nozzle shows
less bowl interaction
with reduced mixture
in Zone D
80
60
40
20
0
© Ricardo plc 2005
340
350
360
370
380
390
400
C ra n k a n g le (d e g )
C as e1l_S toic h
C as e1l_R ic h
C as e1d_S toic h
C as e1d_R ic h
RD05/406501.1 27
Combustion System
Case Study – Diesel Fuel/Air Mixing for High Performance
Comparison of Combustion System Performance from Test Data
C om paris on of S m ok e vs A F R P erform anc e at 4000rev/m in
F ilter S m o ke /(F S N)
3
6 hole nozzle shows
improved smoke/AFR
trade off performance
2
1
6 hole - 1.25m m protrus ion - C as e 1l
7 hole - 1.25m m protrus ion - C as e 1d
© Ricardo plc 2005
0
14
16
18
20
22
24
26
28
S pindt A F R
RD05/406501.1 28
Case Study – Diesel Combustion Modelling
Ricardo Two Zone Flamesheet Model Explanation
 Overview
– Auto-ignition by delay probability
integral
– Simplified coherent flamesheet model
with two-zone gas representation
– Emissions chemistry post-processing
 Two-zone model
– Burnt and unburnt
 Each zone has its own enthalpy, fuel mass fraction and air mass fraction
 Transport equations solved for
– 6 mass fractions, 1 auto-ignition PDF, 4 segregation mass fractions, 2 emissions, 3 enthalpies
© Ricardo plc 2005
 3 temperatures calculated for each cell
– Overall, burned and unburned
 Fast reactions based on chemical equilibrium calculations
– 11 species
RD05/406501.1 29
Case Study – Diesel CFD Combustion Simulation
Analysis Process
 Two-stage simulation
© Ricardo plc 2005
– Compression stroke simulation from IVC to SOI
• Swirl imposed as solid body rotation at IVC
(based on steady flow rig data)
• Trapped mass calculated based on measured
fuelling and air/fuel ratio (including EGR)
• Solving for momentum, continuity, turbulence
and energy
– Spray and combustion simulation from SOI to
EVO
• Spray: Lagrangian discrete droplet method with
Patterson-Reitz droplet breakup model
• Combustion: RTZF combustion model
• NOx: extended Zeldovich NOx model
RD05/406501.1 30
Case Study – Diesel CFD Combustion Simulation
Operating Conditions
 HSDI engine running at full load
– 4000 rev/min full load
– Injection timing swing
© Ricardo plc 2005
 Combustion modelling prediction
– Development of fuel/air mixing analysis
process
– Animation showing temperature
distribution within chamber at rated
speed full load
RD05/406501.1 31
Case Study – Diesel CFD Combustion Simulation
Combustion Modelling Results
 Cylinder pressure trends well produced
M e a s u r e d v s P r e d ic te d P m a x
© Ricardo plc 2005
M a x im u n C y lin d e r P re s s u re [B a r]
170
M e a s ure d
160
V e c tis
150
140
130
120
110
100
-1 8
-1 6
-1 4
-1 2
-1 0
-8
-6
-4
-2
S ta rt o f In je c tio n [C A d e g ]
RD05/406501.1 32
Case Study – Diesel CFD Combustion Simulation
Combustion Modelling Results
 NOx emissions trend well reproduced
M e a s u r e d v s P r e d ic te d N O x
3000
M e a s ure d
2500
V e c tis
NO x [p p m ]
2000
1500
1000
500
0
© Ricardo plc 2005
-1 8
-1 6
-1 4
-1 2
-1 0
-8
-6
-4
-2
S ta rt o f In je c tio n [C A d e g ]
RD05/406501.1 33
Case Study – Diesel CFD Combustion Simulation
Combustion Modelling Summary
 Combustion modelling experience shows cylinder pressure
generally well reproduced
– Over-predicted at earlier timings
– Under-predicted at later timings
– SOC generally captured well
 NOx emissions trend well reproduced
– NOx decreases with injection retard
– Follows cylinder pressure trend
• NOx over-predicted at early timings
• NOx under-predicted at later timings
© Ricardo plc 2005
 CFD analysis provides valuable information and understanding the HSDI combustion
processes to support analytical system development
 Routine application to diesel system development including:
– Air motion generation and requirements
– Combustion chamber geometric configuration
– FIE system configuration
RD05/406501.1 34
Agenda
 Background
 Combustion System Simulation
 Intake, Exhaust and Aftertreatment System
 Engine Thermal Modelling
 Crankcase Breathing
© Ricardo plc 2005
 Vehicle Simulation
RD05/406501.1 35
Intake, Exhaust and Aftertreatment
Intake System Simulation Applications
 Intake system
– 1D performance simulation
• Intake system design
• Boosting system design and
development
– 3D CFD
• Flow performance prediction
• AFR distribution prediction
• EGR distribution prediction
© Ricardo plc 2005
– Flow testing
• Manifold flow assessment
RD05/406501.1 36
Intake, Exhaust and Aftertreatment
Exhaust System Simulation Applications
 Exhaust system
– 1D performance simulation
• Exhaust system design
• Boosting systems
• Warm-up modelling
© Ricardo plc 2005
– 3D CFD
• Flow distribution assessment
• Transient performance
predictions
• Coupled fluid/thermal
modelling
• Catalyst flow predictions
RD05/406501.1 37
Intake, Exhaust and Aftertreatment
Intake and Exhaust System Simulation Methodology
 Coupled 1D/3D simulation used extensively as a routine application on exhaust and
intake system modelling
– Improved modelling for 1-D simulation
– Improved boundary conditions for 3-D simulation
– Provide a tool to address a wide range of technical problems
• Intake system – Air / EGR distribution
• Exhaust system – Flow performance / catalyst flow distribution
• EGR system – Flow performance / dynamic behaviour
– Assess impact of development on engine performance
© Ricardo plc 2005
 Integration is characterised by coupling at a time-step level the 1-D gas dynamic code
(WAVE) and a 3-D CFD code (VECTIS/STAR-CD)
RD05/406501.1 38
Intake, Exhaust and Aftertreatment
Case Study – Exhaust System Simulation
Background
 Base manifold design support project using CFD and FE
analysis to drive manifold design
 Vehicle application required use of close coupled catalyst
but package constraints were stringent
© Ricardo plc 2005
 Focus of fluid simulation
– Assess performance benefit of 4-2-1
compared to 4-1 manifold
– Assess catalyst flow distribution and
recommend design development
– Assess sensor location
Design 2b
Design 1
RD05/406501.1 39
Intake, Exhaust and Aftertreatment
Case Study – Exhaust System Simulation
Analysis Process
 Engine package models integrated rapidly into CFD tool and mesh generated
automatically
 Catalyst model used test data to match
test rig pressure drop
1-D flow region
© Ricardo plc 2005
 Coupled 1D/3D analysis undertaken at
part load 50 km/hr cruise condition
– 1600 rev/min 15 Nm torque
 Coupled 1D/3D uses shadow 1-D network
for “n” cycles followed by embedded 3-D
model with full two-way exchange of
boundary conditions at time step level
RD05/406501.1 40
Intake, Exhaust and Aftertreatment
Case Study – Exhaust System Simulation
Assessment Criteria
 Flow distribution assessed in three ways
– Maldistribution - SAE 910200
– Uniformity index (g) - SAE 960564
– Cumulative velocity PDF
V e l o c i ty P D F - F u l l L o a d
1 .0
0 .9
0 .8
C u m u lative P ro b ab ility
0 .7
0 .6
0 .5
0 .4
0 .3
0 .2
0 .1
0 .0
0 .0
5 .0
1 0 .0
1 5 .0
2 0 .0
2 5 .0
3 0 .0
3 5 .0
© Ricardo plc 2005
V e lo c it y ( m /s )
  1
1
2n
n

i 1
( w i  w mean )
2
w mean
RD05/406501.1 41
Intake, Exhaust and Aftertreatment
Case Study – Exhaust System Simulation
Part Load Simulation Results
Design 1
V e lo city P D F
1
1 .0
0 .9
0 .9
0 .8
0 .8
0 .7
0 .7
C u m u lative Pro b ab ility
C u m u lative Pro b ab ility
V e lo city P D F
0 .6
0 .5
0 .4
0 .3
0 .2
Design 2b
0 .6
0 .5
0 .4
0 .3
0 .2
0 .1
De s ig n 1 ( Un if o r mity In d e x = 0 .9 3 )
0 .1
De s ig n 2 b ( Un if o r mity In d e x = 0 .9 9 )
0
1 .0 0
0 .0
1 .5 0
2 .0 0
2 .5 0
3 .0 0
1 .0
© Ricardo plc 2005
V e lo c it y ( m /s )
1 .5
2 .0
2 .5
3 .0
V e lo c it y ( m /s )

PDF indicates reasonably well distributed
flow

Velocity PDF indicates better velocity distribution
compared to Designs 1 and 2

Uniformity index = 0.93

Uniformity index = 0.99
RD05/406501.1 42
Intake, Exhaust and Aftertreatment
Case Study – Exhaust System Simulation
Sensor Location Assessment
 Assessment of sensor location based on
individual cylinder contribution to flow at
specified sensor location
Design 1
 Design 1 shows a good balance of individual
cylinders present at baseline sensor position
© Ricardo plc 2005
Design 2b
 Design 2 shows a poor balance of individual
cylinders present at “design” O2 sensor position
– Dominated by CYLINDER 2
RD05/406501.1 43
Intake, Exhaust and Aftertreatment
Case Study – Exhaust System Simulation
Alternative Lambda/O2 Sensors
 Design 2 Part Load
– Alternative sensor locations assessed rapidly through extraction of revised
simulation results for various locations
© Ricardo plc 2005
Sensor 1
Sensor 2
RD05/406501.1 44
Intake, Exhaust and Aftertreatment
Aftertreatment Simulation
- Emissions Control Technology (ECT) Model Range
Background
 Diesel
– Diesel Oxy-Catalyst (DOC)
– Diesel Particulate Filter (DPF)
• (including CRDPF and CDPF)
– Lean NOx Traps (LNT)
– Urea Selective Catalyst Reduction (SCR)
© Ricardo plc 2005
 Gasoline
– Three Way Catalyst (TWC)
– Lean NOx Traps (LNT)
DPF flow
CRDPF
RD05/406501.1 45
Intake, Exhaust and Aftertreatment
Aftertreatment Simulation – Methodology
ECT System Design
DOC
DPF
SCR
Common vectorised approach
passes species from unit to
unit
Exhaust system building
from component blocks
© Ricardo plc 2005
DOC
DPF
SCR
RD05/406501.1 46
Intake, Exhaust and Aftertreatment
Methodology – ECT General Model Structure
ECT General Model Structure
Engine
maf
T
Speed
emissions
P
T
O2
O2
NO
NO
NO2
NO2
Pm
Pm
HC
© Ricardo plc 2005
Thermal
sub-model
P
T
Load
MAPS
maf
maf
Catalysis
sub-model
Pressure
sub-model
HC
Geometry
CO
Material
properties
SOx
SOx
CO2
CO2
etc.
etc.
CO
RD05/406501.1 47
Case Study – Aftertreatment Assessment of Exhaust System Layout
Background
 Project to assess a number of different exhaust configurations in different vehicle
packages (Front facing, rear facing, CC CDPF)
 Analysis set-up as shown (test data based)
© Ricardo plc 2005
 Investigations included
assessment of
– System specification
including insulated pipes
– Different catalyst
specifications
RD05/406501.1 48
Case Study – Aftertreatment Assessment of Exhaust System Layout
Example Cycle Emissions Data
CO cumulative
1.4E-02
1.20 g/km
Engine out
1.2E-02
DOC CC
1.0E-02
DOC UF
(kg)
8.0E-03
6.0E-03
4.0E-03
 Example comparison of
cumulative emissions post DOC
for under floor against close
coupled
0.40 g/km
2.0E-03
0.0E+00
0
200
400
600
800
1000
1200
time (s)
HC cumulative
3.0E-03
Engine out
2.5E-03
DOC UF
2.0E-03
(kg)
0.24 g/km
DOC CC
1.5E-03
1.0E-03
0.09 g/km
© Ricardo plc 2005
5.0E-04
0.0E+00
0
200
400
600
time (s)
800
1000
1200
RD05/406501.1 49
Case Study – Aftertreatment Assessment of Exhaust System Layout
Conversion Matrix for Assessed System Configurations
C o n v e r s io n m a t r i x
85 %
83 %
B1
C O c o n v e r s io n ( % )
81 %
B
79 %
B2
D
77 %
E
D in s
E in s
75 %
A'
A ' in s
73 %
F in s
C3
71 %
C2
F
C1
C
69 %
A in s
© Ricardo plc 2005
67 %
65 %
60 %
65 %
7 0%
75 %
80 %
8 5%
H C c o n v e r s io n ( % )
RD05/406501.1 50
Aftertreatment Simulation – Methodology
Coupling V-SIM ECT & CFD Methodology
 Co-simulation: V-SIM ECT models can be linked to VECTIS or Star CD to increase the
resolution of the airflow and concentration distribution over the catalyst front face I.e.
SCR system simulation
 Link 1-D chemistry and thermal models from the VSIM environment to a CFD airflow
prediction model
 Investigate parameters including
– Light off of close-coupled catalyst
– Ammonia slip
© Ricardo plc 2005
 Analysis of airflow maldistribution impact on
emissions performance and potential
cost/benefit ratio investigations from
package/aftertreatment configuration changes
RD05/406501.1 51
Aftertreatment Simulation – Methodology
Coupling V-SIM ECT & CFD Methodology
 CFD simulation at selected engine keypoints
– Output transient flow distribution on the catalyst face
– Average flow over entire engine cycle
+
© Ricardo plc 2005
+
SUM /
Nsteps
+
+
CYCLE AVERAGE
RESULTS
RD05/406501.1 52
Aftertreatment Simulation – Methodology
Coupling V-SIM ECT & CFD Methodology
© Ricardo plc 2005
 CFD simulation output
– Discretise front face
according to zones of
similar mass airflow
 Use outputs from front
face discretisation
(average airflow in each
zone, heat transfer area
between zone i and
zone j) to connect a set
of 1D ECT models
together, ultimately
providing a 3D model
RD05/406501.1 53
Agenda
 Background
 Combustion System Simulation
 Intake, Exhaust and Aftertreatment System
 Engine Thermal Modelling
 Crankcase Breathing
© Ricardo plc 2005
 Vehicle Simulation
RD05/406501.1 54
Engine Thermal Modelling
Base Engine Thermal Development
Background
 Toolset for application to thermal
development of base engine components
 Engineering development applied through
use of advanced analysis tools providing
understanding of principal issues
© Ricardo plc 2005
 Fluid simulation analysis capabilities
include:
– Steady flow coolant circuit simulation
coupled to external circuit modelling
– Coupled fluid/thermal
simulation for steady
state and transient
engine thermal
modelling
COMPLETE
ENGINE ASSEMBLY
MODELLING
RD05/406501.1 55
Engine Thermal Modelling
Base Engine Thermal Development
velocity
temperature
density
Void fraction
0.2
363
60
0.0
– Steady state and transient thermal predictions
with transient thermal boundary condition
application for warm-up/drive cycle simulation
Velocity (m/s)
Temperature (K)
Density (kg/m3)
Void fraction
 Principal tools applied
– Conjugate heat transfer analysis
• Localised coolant warm-up effect modelled
with nucleate boiling and buoyancy modelling
in low / no flow regimes
0.4
381
1020
1.0
Background
Heating surface starts
Heating surface ends
© Ricardo plc 2005
NUCLEATE
BOILING
VALIDATION
0.20
Velocity
(m/s)
– Prediction of:
• Peak temperature distribution during early
engine definition, capturing cylinder to cylinder
variation in metal temperatures
• Thermal shock modelling
• Engine warm up modelling during cold start
• Heat soak thermal prediction
• Assessment of thermal sensor location for
capture of engine response
• Detailed engine thermal mapping for
application of controlled cooling flow regimes
0.41.0
363
60 0.45
10204
Temperature (K)
Density (kg/m3)
3812
RD05/406501.1 56
Engine Thermal Modelling
Base Engine Thermal Development
Coolant Flow Simulation
 Application of CFD analysis to optimise the coolant flow system for:
– Cylinder to cylinder flow distribution
– Flow within recommended velocity guidelines
– Strategic cooling and heat transfer in critical areas
– Minimisation of areas of stagnant flow and excessive flow velocity
– Minimum pressure drop
– Fast warm-up
© Ricardo plc 2005
 Engineering solutions to issues delivered rapidly to address project issues
RD05/406501.1 57
Engine Thermal Modelling
Base Engine Thermal Development
Coolant Flow Simulation
 Poor cooling of upstream
inlet/exhaust valve bridge
© Ricardo plc 2005
 Features added to guide
alternative source of flow
 Head coolant
volume reduced
by sculptured
water jacket
(0.7l)
RD05/406501.1 58
Engine Thermal Modelling
Base Engine Thermal Development
Nucleate Boiling Study
 Complete engine assembly for half of a
V-6 engine
Head
 Fluid flow CFD domain consists of
head, gasket and cylinder block
– Conventional longitudinal flow regime
Coolant in
Coolant out
Liner1
Coolant
passage
Liner2
 Sub-cooled nucleate boiling model
developed for these applications
allowed
Liner3
© Ricardo plc 2005
 Assessment of boiling level and cause
within engine structure
Gasket
Block
RD05/406501.1 59
Engine Thermal Modelling
Base Engine Thermal Development
Nucleate Boiling Study
 Comparison of predicted metal temperature field with boiling model
NO NUCLEATE
BOILING
MODELLED
© Ricardo plc 2005
NUCLEATE
BOILING
MODELLED
RD05/406501.1 60
Engine Thermal Modelling
Base Engine Thermal Development
Nucleate Boiling Study
 Nucleate boiling modelling capability allows:
– Assessment of risk of boiling onset within engine configuration
• prevention of excessive localised boiling leading to erosion issues
– Specification of system components to inhibit boiling within engine
© Ricardo plc 2005
– Optimisation of cooling system to minimise boiling risk
• providing optimised margin allowing for increased local heat transfer should
boiling occur
RD05/406501.1 61
Engine Thermal Modelling
Engine Transient Thermal Modelling
Analysis Process
 Build complete engine thermal model from CAD data
– Typically at least 15 major components

COMPLETE ENGINE
ASSEMBLY
MODELLING
Steady state or transient thermal boundary conditions calculated
– Information input included
• transient engine flow rates
• transient fuelling
• transient gas temperature data from 1D or test data
– Instantaneous heat flux calculated
• Based on input data
• Distribution data applied and mapped to engine structure
© Ricardo plc 2005
 Simulations capabilities include:
– Steady state temperature prediction
• Fixed heat flux, fixed coolant flow, single time
– Fixed engine condition warm-up
• Fixed heat flux, fixed coolant flow, single time
– Fully transient warm-up or load step engine condition change
• Transient heat flux, transient coolant flow, time marching
RD05/406501.1 62
Case Study – Engine Transient Thermal Modelling
Engine Thermal Shock Modelling
Temperature Distribution After 30 Seconds
© Ricardo plc 2005
CONVENTIONAL
WATER PUMP
THERMOSAT
CLOSED
RATED SPEED
THERMAL
SHOCK FROM
25°C
0 to 30 seconds
LOW FLOW
WARM-UP
THERMOSAT
CLOSED
RATED SPEED
THERMAL
SHOCK FROM
25°C
0 to 30 seconds
RD05/406501.1 64
Case Study – Engine Transient Thermal Modelling
Summary
 Transient thermal prediction tools allow system mapping and detailed modelling of
powertrain thermal behaviour
© Ricardo plc 2005
 Process supports:
– Efficient thermal management strategies
– Detailed understanding of engine thermal behaviour
RD05/406501.1 65
Agenda
 Background
 Combustion System Simulation
 Intake, Exhaust and Aftertreatment System
 Engine Thermal Modelling
 Crankcase Breathing
© Ricardo plc 2005
 Vehicle Simulation
RD05/406501.1 66
Crankcase Breathing
Crankcase Breathing Simulation
Background
 Engineering closed crankcase breather systems essential for optimisation of engine
performance, emissions and durability
 Engineering issue path
– Minimise engine blow-by
• Reduce separator system flow requirements
• Minimise oil carryover
– Optimisation of breather system
• Minimise pumping work for transfer of blow-by gas to intake
• Optimisation of PCV valve characteristics
• Maximise crankcase depression
– Component optimisation
© Ricardo plc 2005
• Separator
• PCV valve
 Engine structural implications
– Bulkhead design optimisation
– Crankshaft profile
RD05/406501.1 67
Crankcase Breathing
Crankcase Breathing Simulation
1D Analysis Methodology
 Objectives
– Prediction of crankcase pumping work
– Validation of boundary conditions
– Investigation into bay-to-bay breather area effects
© Ricardo plc 2005
 Full gas flow path modelled in 1D with WAVE to
represent complex 3D geometry
– Blow-by flow applied from test data or
simulation
– Bulk motion predicted in crankcase
system
• Interbay breathing
• Oil drainback chimneys
• Chain/gear case flow
• Cam cover flow
• PCV valve
Oil drainback chimneys
PCV valve
Blowby
Chaincase
Interbay breathing
RD05/406501.1 68
Crankcase Breathing
Crankcase Breathing Simulation
1D Analysis Methodology
 Techniques validated for prediction of system
dynamic pressures against engine testbed data
Separator In
 Engine performance impact on oil flow levels
and rates can be considered
– E.g. piston cooling jets draw additional oil
from sump around 2000rpm causing level to
drop at this point and as speed increases
– Simulation varies the oil level with speed
RaAmplitude
n g e o f F lu c tu a tio
n s (Ba r)
(Bar)
© Ricardo plc 2005
Simulation
Test
0 .0 1 2
0 .0 1
0 .0 0 8
0 .0 0 6
0 .0 0 4
0 .0 0 2
0
0
1000
2000
3000
4000
5000
E n g in e S p e e d (rp m )
Te s t R e s ults V e nte d to A m b ie nt
Te s t R e s ults C lo s e d S ys te m
S im ula tio n R e s ults V e nte d to A m b ie nt
S im ula tio n R e s ults C lo s e d S ys te m
Crankcase Bay RD05/406501.1
69
Crankcase Breathing
Case Study – Crankcase Breathing Simulation
 V6 Breather Circuit Study
– Model generated using WAVEBUILD-3D to represent volumes
– 1D model to assess breather system performance based upon areas of concern
• Reduce velocity variation at separator inlet to improve separator performance
• Reduce regions of high velocity magnitude throughout system
– Block transfers from crankcase to V () and can breathe through head passages
only (), bypassing V
– Use head volumes to damp out pressure fluctuations and provide additional
separation
T o s e p a ra to r
Vee
© Ricardo plc 2005
H ead
H ead
C ra n k c a s e
Fluctuations at
separator in are
damped by the
increased
distance and more
restrictive
passages than
baseline which
breathes mainly
through centre of
banks
RD05/406501.1 70
Crankcase Breathing
Crankcase Breathing Simulation
Application to Engine Development
 1D Crankcase Simulation
– Dynamic system model to match measured high
speed crankcase pressures
– Provides analysis of system behaviour
across engine speed range
– Identifies critical speeds for detailed modelling
CPMEP with additional
breather channel as
suggested by WAVE
Original, target
CPMEP
© Ricardo plc 2005
CPMEP with
proposed
breather removal
 3D CFD Simulation
– Detailed system modelling based on 1D findings
– Incorporation of moving geometry
• Including complete rotating/reciprocating component motion
– Simulation of complete crankcase will not model oil mist directly
• Simulation of mist through high density scalar fraction
• Liquid modelling for free surface motion possible but adds
significant complexity and of low value for dry sump systems
– Extraction of detailed pumping work for individual
components/system regions
• Optimisation of breathing/scavenge flow regimes possible
• Optimisation of geometric configuration to minimise
aerodynamic/pumping losses
RD05/406501.1 71
Crankcase Breathing
Crankcase Breathing Simulation
3D Oil Separator Development
 Oil separator development
using coupled 1D/3D
simulation
 Engineering support to
cyclone design
© Ricardo plc 2005
 Rapid approach using steady state or transient
single phase flow analysis or transient 2 phase flow
analysis with wall film modelling
 Methodology developed to assess separator
efficiency based on predicted flow regime
RD05/406501.1 72
Crankcase Breathing
Crankcase Breathing Simulation
Case Study – 3D Oil Separator Development – Cyclone Separator Selection
 Choice of cyclone aided by CFD.
900
rad/s
 VECTIS shows both the single cyclone and multi cyclone display
classical behaviour along their entire length
 VECTIS predicts the angular velocity down the complete cyclone
length
 Knowing the velocity profile allows the cyclone to be matched to
the oil particle size distribution
SWIRL DEGREDATION ALONG HEIGHT
650
Rad/s
1000
Entry
© Ricardo plc 2005
350
rad/s
ANGULAR VELOCITY (rad/s)
450
rad/s
900
Single Cyclone
800
Quad Cyclone
700
600
500
400
300
200
100
0
0
10
20
30
40
50
60
PERCENTAGE OF HEIGHT
70
80
90
100
RD05/406501.1 73
Crankcase Breathing
Crankcase Breathing Simulation
© Ricardo plc 2005
Case Study – 3D Oil Separator Development – Transient Flow Analysis
RD05/406501.1 74
Agenda
 Background
 Combustion System Simulation
 Intake, Exhaust and Aftertreatment System
 Engine Thermal Modelling
 Crankcase Breathing
© Ricardo plc 2005
 Vehicle Simulation
RD05/406501.1 75
Vehicle Simulation
Vehicle Simulation
Background
 The integrated design of both engine and vehicle hardware are key to meeting
performance and emissions targets
 Applications include
– Matching of engine performance to
vehicle weight
– Gear ratio selection
– Air system control strategy definition
and calibration
– Boost system selection
– Calibration comparison
180
R o a d S p e e d (k m /h )
160
100
80
60
1 .4 litre tu rb o c h a rg e d L B D I C a l 1
40
1 .4 litre tu rb o c h a rg e d L B D I C a l 2
0
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
T im e (s )
X2
Vv
θV
CF
KF
KR
FV
CR
ZV
ZF
FF
© Ricardo plc 2005
120
20
X1
VW
140
ZR
FR
FT
RD05/406501.1 76
Vehicle Simulation
Vehicle Simulation
Methodology
 Validated steady state WAVE model is converted to transient and coupled to either
Vehicle model
 ECU developed within Simulink and coupled to vehicle model
 The model is run through transient load step / drivecycle manoeuvres
© Ricardo plc 2005
Control systems
RD05/406501.1 77
Vehicle Simulation
Case Study – Vehicle Simulation
Validation
© Ricardo plc 2005
 Drive cycle simulation
shows engine and vehicle
response to gear and
pedal position for a fixed
manoeuvre validate
closely to test data
Source:
RD05/406501.1 78
Vehicle Simulation
Case Study – Vehicle Simulation
Validation
© Ricardo plc 2005
 Drive cycle simulation
shows vehicle fuel
consumption through a
1200 second NEDC
cycle validates closely
to test data
Source:
RD05/406501.1 79
Vehicle Simulation
Case Study – Vehicle Simulation
Case Study – Boost System Selection Study
© Ricardo plc 2005
 A number of alternative boost systems were
modelled and their acceleration performance
compared
– Single stage turbocharger
– Supercharger + turbocharger
– Supercharger only
– Electrically driven compressor (EDC)
+ turbocharger
– Electrically Assisted turbocharger
– Two stage turbocharger
Source:
RD05/406501.1 80
Vehicle Simulation
Case Study – Vehicle Simulation
5
Engine Speed
5000
2.5
4000
2
3000
1.5
Boost
x 10
Case Study – Boost System Selection Study
 The baseline system
(turbocharger only) was
validated to measurements
 The controllers for each device
were tuned to provide optimum
performance
 Tip in boost response for two
systems
– Boost system calibration
carried out using simulation
models
2000
1
1000
0.5
0
0
2
4
6
8
10
12
14
5000
120
2.5
100
100
4000
1208
0
2
4
6
8
10
12
14
4
Vehicle
Speed 0 time= 0sWastegate
100 time=
13.55s 0->100kph= 13.55s
Area
x 10
Engine Speed
10
12
14
2
44
66
88
10
10
12
12
14
14
10
10
12
12
14
14
10
12
14
wheelgear
spdand
& ang veh spd
Boostclutch
5
100
1.5 x 10
2.5
1.5
40
2000
2
40
0.5
1
20
2
1
60
20
1000
0.5
0
4
0x 10
2
4
2
4
6
8
Wastegate
6 TorqueArea
8
10
12
14
10
12
14
0
0
0
0x 10-3
1.55
Speed13.04s 0->100kph= 13.04s
Vehicle Speed 0 time= 0sEngine
100 time=
5000
120
2.50
100
100
4000
100
804
3000
6020
2000
40
-1000
1000
20 0
2
80
-5
2006
2
44
2
4
5
66
88
gear
6 and
8
Slipclutch
wheel spdBoost
& ang veh spd
x 10
1
1.5
60
-10
0.5
-15
401
2
4
6
8
10
12
14
2
4
6
-20
0.5
200 0
2
EDC
+66 Turbocharger
44
88
10
12
14
10
12
14
-3
Torque
300 0
8
10
12
14
4
Vehicle
Speed 0 time= 0sWastegate
100 time=
13.04s 0->100kph= 13.04s
Area
x 10
200
1208
© Ricardo plc 2005
0
0
3000
604
0 x 10
50
Slip
2
4
6
8
10
12
14
wheelgear
spdand
& ang
veh spd
clutch
0
100
1.5
-5
100
100
6
80
80
-10
1
60
0
-15
604
-100
40
20
20
0
8
Turbocharger Only
0.5
20
80
3008
6
wheel spdBoost
& ang veh spd
1
40
100
40006
80
0
4
1.5
60
5000
0
2
x 10
2
80
80
3000
60
2000
40
1000
20
0
0
5
Speed13.55s 0->100kph= 13.55s
Vehicle Speed 0 time= 0sEngine
100 time=
0
Source:
0
0
4
x 10
2
4
6
8
10
12
14
2
4
6
8
10
12
14
Wastegate
Torque Area
40
-20
0.5
0
20
0
0
-3
x 10
2
4
2
4
6
8
10
12
14
6
8
10
12
14
gear and
Slipclutch
RD05/406501.1 81
Vehicle Simulation
Case Study – Vehicle Simulation
Case Study – Boost System Selection Study
 Each system was run through the same manoeuvre (3rd gear, 30 km/h, from 0% to
100% Pedal)
© Ricardo plc 2005
 For this example the FGT + EDC provided the best response
Source:
RD05/406501.1 82
Thank you for your attention
ありがとうございました
© Ricardo plc 2005
Any Questions?
どうぞご質問を
RD05/406501.1 83