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Multi-Fuel and Mixed-Mode IC Engine Combustion Simulation with a Detailed Chemistry
Based Progress Variable Library Approach
Contents
• Introduction
• Approach
• Results
• Conclusions
2
Introduction New Combustion Model- PVM-MF
• New Legislations Force Modern ICE Engines
– Higher Efficiency
– Lower Emission
• Modern Engines Organize Combustion Differently
– Wider Range of Oxidizer/Fuel/EGR
– Coexisting Different Types of Combustion
– Multi-Fuel
– Shorter Operating Time Scales (higher Speed)
• A New Combustion Analysis Tool Developed Targeting
– Detailed Chemistry Based
– Capable of Different/Mixed Type of Combustion
– Capable of Multi-Fuel
– Low Computational Cost
3
Contents
• Introduction
• Approach – Flow solver: Turbulent Flow + Species Transport
– Chemistry Solver: Reaction through a Pre-solved
Library
– Bridge: Combustion Progress Variable
• Results
• Conclusions
4
Approach Pre-Solved PVM-MF Library
• Govern equations
• PVM-Library Input/Output:
– A set of pre-solved 0-D solutions is re-organized as
follow function in table form
– The independent variables and dependent variables
5
)(xFy
outputquantityspecies
propertiesthermal
ngtransportireaction
Y
AAM
C
y
EQ
EGR
C
UH
P
x
i
W
/
/
~~,
)(
)(
61
ii w
dt
dY
dt
dp
dt
dH
Approach Pre-Solved PVM Library cont.
– Lookup Library
» CFD flow solver provides to Library, the library
returns any elements of after interpolating
6
x
y
Approach CFD Flow Solver
• Govern Equations:
7
spray
i
i mx
U
t
~
spraym
i
ij
ji
jijm
xx
p
x
UU
t
U,
~~~
sprayH
it
t
ii
i mx
H
xt
p
x
HU
t
H,)
~
(
~~~
sprayii
i
j
t
t
ii
jijmw
x
Y
xx
YU
t
Y,)
~
(
~~~
kk
ik
t
ii
i DGx
k
xx
kU
t
k
)(
~
DG
xxx
U
t i
t
ii
i
)(
~
Approach Combustion Modeling
• Progress Variable and Its Transport Equation
• Thermodynamic Property determination
8
C
it
t
ii
i SCx
C
xx
CU
t
C
)(
~
)()(
)()()(
0298298
0298298
tthtth
tththtC
TendT
TT
i
iiT KThYh )298(298
)//(4
5
3
4
2
321 KkgJTATATATAACP
)/(5432
6
554433221 kgJAT
AT
AT
AT
ATAH
)//( KkgJM
RR
W
universal
Approach Combustion Modeling cont. Four Combustion Modes
• HCCI combustion (base mode):
– Solve progress variable transport equation with
library source term
– Lookup PVM-Lib to obtain thermal properties
and species
• Premixed combustion (premixed mode):
– G-eq determines flame location in SP-
ignition/main combustion stages
– Model C distribution based on G distribution
– Lookup PVM-Lib to obtain thermal properties
and species
•
9
dt
dCC
Approach Combustion Modeling cont.
Four Combustion Modes
• Non-premixed combustion (non-premixed
mode):
– Return to flamelet concept - strain-effect model
– Solve progress variable transport equation with
library source term
– Lookup PVM-Lib to obtain thermal properties
and species
• Mixed Types of Combustion (mixed-type mode)
– Fuel Scalar Dissipation Rate Level Controls
10
Approach Combustion Modeling cont. Base Mode
• For HCCI Combustion
11
CFD Solver
),,,,( CHPx i
PVM-Library
C iBY
Solve Progress Variable C Transport equation
Flamelet Solver for Emissions
61,....., AAMW
Approach Combustion Modeling cont. Premixed Mode
• Flame location
• G-equation
• Flame thickness
• Flame Propagation Speed
12
GSGUt
Gt
1G
zoneburninglGl
zoneunburnedlG
zoneburnedlG
:5.05.0
:5.0
:5.0
5.1kCCl l
)( ltl SSSS
Approach Combustion Modeling cont. Premixed Mode
• For Premixed Combustion
13
CFD Solver
),,
,,(
C
HPx
i
PVM-Library
C
iBY
Solve
Progress
Variable C
Transport
equation in
sub-zone of
G>0.5l and
G<-0.5l
Flamelet Solver for Emissions
61,....., AAMW
Solve G- Equation and
flame thickness l
Linearly distribute C
value inside flame
layer -0.5l<G<0.5l
Approach Combustion Modeling cont. Non-Premixed Mode
• Return to Flamelet Concept
– Strain-Effect Model
– Scalar Dissipation Rate
14
spray
it
t
ii
i mx
Z
xx
ZU
t
Z
)
~
(
~~~
0))((
C
t
C
2"~~
~~ Z
kcx
~)
~
(2
)
~
(
~~~2
2"2"2"
2"~
it
t
i
t
ii
i
x
Z
x
Z
xx
ZU
t
Z
Z
Approach Combustion Modeling cont. Non-Premixed Mode
• For non-Premixed Combustion
15
CFD Solver
),,
,,(
C
HPx
i
PVM-Library
C iBY
Solve
Progress
Variable C
Transport
equation
Flamelet Solver for Emissions
61,....., AAMW
Scalar Dissipation
Solver
Contents
• Introduction
• Approach
• Results
– Demonstration: Mode Concept Explanations
– Demonstration: Application
• Conclusions
16
Result-1 Pancake-Engine Demonstration
17
Engine Configuration and
Mesh arrangement
Engine Parameters
Bore 105mm
Stoke 109mm
Clearance 12.5mm
Speed 1500rpm
Compression Ratio 9.726
Sweep Volume 0.9445 litre
Spark Plug Location Head Centre
Fuel Injector Location Head Centre
No of Inj. Hole 6
Fuel-1 CH4 (gas)
Fuel-2 n-C7H16 (Liquid)
Result-1: Pancake-Engine Demonstration Cont. Same engine runs in 4 different Modes
18
Run Conditions Combustion Mode HCCI Premixed Non-Premixed Mixed-Type
Initial Mass Fraction Yair 0.697 0.855 0.95 0.87
Initial Mass Fraction YEGR 0.27 0.1 0.05 0.1
Initial Mass Fraction YCH4
0.0 0.045 0.0 0.03
Initial Mass Fraction Yn-C7H16
0.033 0.0 0.0 0.0
Total fuel: NG/Diesel(mg) 0.0/96.1 113.8/0.0 0.0/84.0 85.0/20.0
Spark Plug Timing (CA) - 690.02 - -
Start of Injection (CA) - - 708.0 715.0
End of Injection (CA) - - 722.0 719.0
Result-1: Pancake-Engine Demonstration Cont.
HCCI Mode – Development of Progress Variable
19
CA=734 CA=735 CA=736 CA=737 CA=738
CA=739 CA=740 CA=741 CA=742 CA=743
CA=744 CA=745 CA=746 CA=747 CA=748
CA=749 CA=750 CA=751 CA=752
Result-1: Pancake-Engine Demonstration Cont.
HCCI Mode – Development of Temperature
20
CA=734 CA=735 CA=736 CA=737 CA=738
CA=739 CA=740 CA=741 CA=742 CA=743
CA=744 CA=745 CA=746 CA=747 CA=748
CA=749 CA=750 CA=751 CA=752
Result-1: Pancake-Engine Demonstration Cont.
Premixed Mode – Development of Progress Variable
21
CA=692 CA=694 CA=696 CA=698 CA=700
CA=716 CA=720 CA=724 CA=728 CA=732
CA=736 CA=740 CA=744 CA=748
CA=702 CA=704 CA=706 CA=708 CA=712
Result-1: Pancake-Engine Demonstration Cont.
Premixed Mode – Development of Flame front
22
CA=692 CA=694 CA=696 CA=698 CA=700
CA=716 CA=720 CA=724 CA=728 CA=732
CA=736 CA=740 CA=744 CA=748
CA=702 CA=704 CA=706 CA=708 CA=712
Result-1: Pancake-Engine Demonstration Cont.
Premixed Mode – Development of Temperature
23
CA=692 CA=694 CA=696 CA=698 CA=700
CA=716 CA=720 CA=724 CA=728 CA=732
CA=736 CA=740 CA=744 CA=748
CA=702 CA=704 CA=706 CA=708 CA=712
Result-1: Pancake-Engine Demonstration Cont.
Non-Premixed Mode – Spray and Fuel Distribution
24
CA=709 CA=711 CA=713 CA=715 CA=717
CA=719 CA=721 CA=723 CA=725 CA=727
CA=730 CA=733 CA=736 CA=739 CA=742
Result-1: Pancake-Engine Demonstration Cont.
Non-Premixed Mode – Development of Progress Variable
25
CA=709 CA=711 CA=713 CA=715 CA=717
CA=719 CA=721 CA=723 CA=725 CA=727
CA=730 CA=733 CA=736 CA=739 CA=742
Result-1: Pancake-Engine Demonstration Cont.
Non-Premixed Mode – Development of Temperature
26
CA=709 CA=711 CA=713 CA=715 CA=717
CA=730 CA=733 CA=736 CA=739 CA=742
CA=719 CA=721 CA=723 CA=725 CA=727
Result-1: Pancake-Engine Demonstration Cont.
Mixed-Type Mode – Diesel Spray and Concentration Field
27
CA=716 CA=717 CA=718 CA=719 CA=720
CA=721 CA=722 CA=724 CA=726 CA=729
CA=732 CA=735 CA=738 CA=741 CA=744
CA=747 CA=750 CA=755 CA=760
Result-1: Pancake-Engine Demonstration Cont.
Mixed-Type Mode – Development of Progress Variable
28
CA=716 CA=717 CA=718 CA=719 CA=720
CA=721 CA=722 CA=724 CA=726 CA=729
CA=732 CA=735 CA=738 CA=741 CA=744
CA=747 CA=750 CA=755 CA=760
Result-1: Pancake-Engine Demonstration Cont.
Mixed-Type Mode – Development of Flame Front
29
CA=716 CA=717 CA=718 CA=719 CA=720
CA=721 CA=722 CA=724 CA=726 CA=729
CA=732 CA=735 CA=738 CA=741 CA=744
CA=747 CA=750 CA=755 CA=760
CA=747 CA=750 CA=755 CA=760
Result-1: Pancake-Engine Demonstration Cont.
Mixed-Type Mode – Development of Temperature
30
CA=716 CA=717 CA=718 CA=719 CA=720
CA=721 CA=722 CA=724 CA=726 CA=729
CA=732 CA=735 CA=738 CA=741 CA=744
CA=747 CA=750 CA=755 CA=760
Result-1: Pancake-Engine Demonstration Cont. Mean Pressure,Temperature,Heat Release Rate,Prog. Variable
31
HCCI Mode
Mixed Type Mode Non-Premixed Mode
Premixed Mode
Result-1: Pancake-Engine Demonstration Cont. Summarize: Physical/Chemical processes covered by each mode
• HCCI mode:
– Auto-Ignition/Knock based on detailed chemistry solutions
– Single or Multi-Fuel (or Fuel + Others, e.g. Water, CO2, N2....)
– Emission (NOx, Soot and CO)
• Premixed mode:
– All Processes in HCCI mode
– Flame Propagation
– Spark Plug(s) Ignition
• Non-Premixed Mode:
– All Processes in HCCI mode
– Single and Multi-Injection Models (interactions among pilot, main and post-
injections)
– Interactions between flow/turbulence/mixing and ignition/combustion
• Mixed-Type Mode:
– All Processes in HCCI, Premixed and non-Premixed modes
– Model multi-mode combustion simulation at same location instantaneously
32
Result-2: Natural Gas Engine Parameters and Mesh Arrangement
33
Ignition Mode SI MP
Bore/stoke/rod length 250/250/500mm
Engine speed 750rpm
Premixed fuel EQ and
EGR Conc.
0.4914/0.1
Assistant fuel in pre-
chamber
NG Diesel
Sweep Volume 12.3liters
Pre-chamber volume % 1.5%
Assistant fuel injection
masses
4.35mg 3.03mg
Assistant fuel injection
timings
652.6 708CA
Result-2: Natural Gas Engine Cont.
Fuels, Prog. Variable, Flame Front, Temp.,Turbulence, Velocity
34
Result-2: Natural Gas Engine Cont.
Mean Pressure, Temperature and Progress Variable
35
HPDI Technology
Natural gas as primary fuel, along with a small amount of Diesel
as a pilot ignition source – liquid spark plug
One injector for both fuels
Picture source: http://www.westport.com/is/core-technologies/combustion
Demo case engine technical data
Artificial gas engine for demo purpose
– Bore 130
– Stroke 150
– Conrod 260
– Compression ratio 18
Case condition
– Engine speed 1500 rev/min
– AFR-NG 30.3, AFR-Diesel 273
– EGR 2.5%
– Fuel injection
• SOI Diesel 707oCA, Duration 3o
• SOI Gas 711oCA, duration 16o
Results
Cylinder pressure and temperature
0
200
400
600
800
1,000
1,200
1,400
1,600
1,800
0.0E+00
2.0E+06
4.0E+06
6.0E+06
8.0E+06
1.0E+07
1.2E+07
1.4E+07
1.6E+07
1.8E+07
2.0E+07
600 630 660 690 720 750 780
Tem
pe
ratu
re (K
)
Pre
ssu
re (
Pa)
Crankangle (deg)
Pressure
Temperature
Results
Heat release rate
0.0E+00
2.0E+05
4.0E+05
6.0E+05
8.0E+05
1.0E+06
1.2E+06
1.4E+06
1.6E+06
1.8E+06
2.0E+06
700 710 720 730 740 750 760 770 780 790 800
He
at r
ele
ase
rat
e (J
/sec
)
Crankangle (deg)
Results – Field distribution
711.5
oC
A
Diesel PV NG T
712oC
A
710oC
A
708oC
A
Results – Field distribution
717oC
A
Diesel PV NG T
720oC
A
715oC
A
713oC
A
Results – Field distribution
736oC
A
Diesel PV NG T
760oC
A
729oC
A
724oC
A
Contents
• Introduction
• Approach
• Results
• Conclusions
43
Conclusions
• 1. PVM-MF has been developed. Its main features are
– Detailed chemistry based
– Capable of different and mixed- types mode of combustion
– Capable of multi-fuel operation
– Low computational cost
• 2. Chemistry solutions stored in PVM-library. Couple
CFD/chemistry solutions through progress variable
• 3. PVM-MF saves computational cost in two ways:
– Only solve Base species/Prog. Variable transport Eqs
– Pre-calculated library for Reaction/Properties
• 4. Practices proves PVM-MF works in primary
tests/validations
44
Thank You !
45
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