Multi-Fuel and Mixed-Mode IC Engine Combustion...

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


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


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


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


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


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


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


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


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


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


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


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


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


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


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


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

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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


717oC

A

Diesel PV NG T

720oC

A

715oC

A

713oC

A


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 !

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Multi-Fuel and Mixed-Mode IC Engine Combustion...

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