Analysis Led Design for Engine System Development to Meet US2010

ERC – 2005 Symposium 1

Analysis Led Design for Engine System Development

Analysis Led Design for Engine System Development to Meet US2010 Emission Standards

ERC - 2005 Symposium

Donald Stanton, Ph.D.

Cummins, Inc.



Worldwide Emissions Levels:171 – 751 HP

0 1 2 3 4 50.00

0.02

0.04

0.06

0.08

0.10

Parti

cula

te [g

/kW

Parti

cula

te [g

/kW

-- hr]hr]

US07US10

EURO-V EURO-IV

Transient

0.12

0.14

Tier IV ATier IV B

US02/04

EURO-VI

Japan - NLT

NOx [g/kWNOx [g/kW--hr]hr]



Analysis Led Engine Development

Cycle Simulation Work• EGR system config.• VVT strategy• Air Handling strategy

Cyber Modeling• Control strategy

CFD Work• Combustionsystem optimization

SCE Testing• Model validation

MCE Testing• System validation

Cycle Simulation Work• EGR system config.• VVT strategy• Air Handling strategy

Cyber Modeling• Control strategy

CFD Work• Combustionsystem optimization

SCE Testing• Model validation

MCE Testing• System validation


Analysis Led Design for Engine System Development Analysis Tool

Air SystemSimulation

CFD Combustion Code

Optimization

Fuel SystemSimulation

σ

TemperaturesPressuresAir Flows

NOx

PM

Crank Position

Inj P

ress

Crank Position

HRR

Crank

Current

AftertreatmentSimulationN

Ox

Con

vers

ion

time



Combustion CFD Tool Improvements

• Combustion model (extensive validation for multiple injection – up to 5 events)

• Improved kinetics mechanisms- Varying Cetane Number- More low temperature chemistry

• Complex Grids

• Grid independent spray modeling

• Computing Power

Rig Data8 (mesh size / nozzle dia.)420.5

Can Refine The Grid to ReduceGrid Sensitivity Issues

Pen

etra

tion

(cm

)

Time (ms)

8

6

4

2

0

0 0.5 1.0 1.5 2.0

New Spray Model

Detailed Geometry



Heavy Duty EngineDevelopment

Sensors

Controls

EGR System

PMAftertreatment

Combustion Recipe(Piston, nozzle, swirl)

NOxAftertreatment

VVT

Fuel InjectionEquipment Turbomachinery



Fuel Injection EquipmentDesign Space

Nozzle Area (Cupflow)

Injection Pressure2002 FIE

FIE Mechanical Limit

Diffusion

Premixed

Lifted Flame

Increasing

Incr

easi

ng

Orifice DiameterIn

ject

ion

Press

ure

# o

f H

ole

s

Example #1

Example #2

Lube Oil Soot Limitand

Power Density



Example #1



Impact of Injection Pressureon Emissions Formation

0

1

2

3

4

5

6

7

8

0 500 1000 1500 2000 2500 3000Temperature (K)

Equi

vale

nce

Rat

io (φ

)

fuel / airmixing

lineIg

nitio

n Zo

neParticulateProduction

ZoneA

B C

D

Diesel

PCCI

B’C’ D’

NOxProduction Zone

T in-cylinder

0

1

2

3

4

5

6

7

8

0 500 1000 1500 2000 2500 3000Temperature (K)

Equi

vale

nce

Rat

io (φ

)

fuel / airmixing

line ParticulateProduction

Zone

ParticulateProduction

ZoneA

B C

D

Diesel

Lifted Flame

B’C’ D’

NOxProduction Zone

T in-cylinder

Increased Injection Pressure

• Increasing injection pressure reduced the residence time in theparticulate productionzone.

• Lower nozzle diametersand further increase ininjection pressure result in lifted flames.

• Increased mixing timeoccurs with lifted flames due to increased strain rate on the flame.



Impact of Injection Pressureon Soot Formation

Soot Formation is a Function of Residence TimeSoot formation depends on equivalence ratio, temperature, and time

Eq

uiv

ale

nce

Rati

o

0-4

0

1

2

3

4

5

6High Injection Pressure Reduces

Residence Time

15.0% O2

1000 K

Increasing Injection Pressure

2 4 6C2H2 Mass Fraction x 10



Fuel Spray Images for Variationin Injection Pressure

Increasing Injection Pressure



Influence of Increased InjectionPressure on Spray Characteristics

0

5

10

15

20

25

30

35

40

0 500 1000 1500 2000 2500Time After SOE (microseconds)

Liq

uid

Pen

etr

ati

on

(m

m) Increasing Injection Pressure

CFD Results

0

5

10

15

20

25

30

35

40

45

50

0 500 1000 1500Time After SOE (microseconds)

Gas

Pen

etr

ati

on

(m

m)

CFD Results



Emissions and Fuel Consumptionfor Varying Injection Pressure

0

0.2

0.4

0.6

0.8

1.0

-15 -10 -5 0

SOI (ATDC)

fsD

PM

(g/k

g f

uel

)

BSFC

(g/k

Wh)

∆=5

Incr

easi

ng I

nje

ctio

n P

ress

ure

0

0.2

0.4

0.6

0.8

1.0

-15 -10 -5 0

SOI (ATDC)fs

DPM

(g/k

g f

uel

)

BSFC

(g/k

Wh)

∆=5

Incr

easi

ng I

nje

ctio

n P

ress

ure

Circle - SmokeDiamond - bsfcCircle - SmokeDiamond - bsfcCircle - SmokeDiamond - bsfc

CFD Model Engine Data

0.22 g/kW-hr bsNOx at 22 bar BMEP



5 bar7 bar

10 bar15 bar20 bar

BMEP

Bra

ke T

her

mal

Eff

. (%

)

Bosc

h S

moke

5 bar7 bar

10 bar15 bar20 bar

BMEP


Analysis Led Design for Engine System Development Conclusions for Example #1

• Higher injection pressure coupled with an optimized combustion recipe(bowl, nozzle, swirl) provide a cost effective option for US2010

- Improved fuel economy- Continued reduction in engine out PM

• According to modeling results, lifted diffusion flames can be achievedfor larger bore engines.

- Difficult to extend to small bore engines

• Higher injection pressure requires significant FIE development.

• Analysis led design process utilized to provide optimized combustion recipe.

• Lower engine out PM provides lower cost of ownership by reducingPM aftertreatment cost and improving fuel consumption.



Example #2



Fuel Injection EquipmentDesign Space

Nozzle Area (Cupflow)

Injection Pressure2002 FIE

FIE Mechanical Limit

Diffusion

Premixed

Lifted Flame

Increasing

Incr

easi

ng

Orifice DiameterIn

ject

ion

Press

ure

# o

f H

ole

s

Example #1

Example #2

Lube Oil Soot Limitand

Power Density



Simulation of Transient Injector Performance of Dual Row Nozzle



Spray Images forIncreased Cupflow Nozzle

Spray Rig CFD Model

100% Load

25% Load



Spray Model Calibrationfor High Cupflow Nozzle

0

10

20

30

40

50

60

0 100 200 300 400 500 600 700 800Time After SOE (microsecond)

Pene

trat

ion

(mm

)

Lower Row – Rig DataUpper Row – Rig DataLower Row – CFD ModelUpper Row – CFD Model



Improving Smoke and CombustionStability with Nozzle Design

and FIE Calibration

0.0

0.1

0.2

0.3

0.4

0.5

0 1 2 3 4 5SOI (ATDC)

Bos

ch #

9% Smaller Diameter

Nominal Diameter

bsNOx < 0.16 g/bhp-hr at 20 bar BMEP

Nominal Diameter – Engine DataNominal Diameter – CFD ModelLower Diameter – Engine DataLower Diameter – CFD Model



fsNOx (g/kg)

0

1

2

3

4

5

6

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0Ignition Delay (msec)

Bos

ch S

mok

e N

umbe

r

5.0 bar10 bar15 bar20 bar

0%

10%

20%

30%

40%

50%

60%

0 5 10 15 20

Gro

ss In

dica

ted

Ther

mal

Eff.

(%)

1 g/kg fsNOx ~ 0.2 g/hp-hr BSNOx

1998 Engine



Conclusions for Example #2

• Higher cupflow and injection pressure provide an option for US2010.

• Detailed CFD modeling of the injector internal flow required to achievedesirable flow characteristics.

• Analysis led design process utilized to provide optimized combustion recipe.

• Lower engine out PM provides lower cost of ownership by reducingPM aftertreatment cost and improving fuel consumption.



Light Duty Engine Example



Extending the LTC Zone

0

100

200

300

400

500

600

700

800

700 1200 1700 2200 2700 3200

Engine Speed [ rpm ]

Torq

ue [

ft-lb

]

CompressionTemperature

Combustion RecipeFIE Calibration

Improved Air HandlingMore Capable Fuel System




Combustion System DesignAnd FIE Calibration

CFD PredictionsEngine Emissions ResultsEGR Sweep at 1800 rpm and 8 bar BMEP EGR Sweep at 1800 rpm and 8 bar BMEP

Bowl #1 - Computed

Bowl #2 - Computed

Bowl #3 - Computed

0.0

0.2

0.4

0.6

0.8

1.0

1.2

fsD

PM (g

/kg

fuel

)

Bowl #1 - Engine Data



fsD

PM (g

/kg

fuel

)

CFD Model Captures Trends

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.0 0 0.2 0.4 0.6 0.8 1.00 0.2 0.4 0.6 0.8

NOx (g/mi) NOx (g/mi)



0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0 500 1000 1500 2000 2500 3000

Gas Temperature (K)

Equi

vale

nce

Rat

io

Soot*

NOx

Ignition ZoneIdeal MixingLine

Soot**

1800 RPM at 8 bar BMEP

10o atdc

1o atdc 30o atdc

4o atdc

Config. #2 does not providedenough mixing to eliminatefuel rich zones.

Fuel rich zones lead to more soot formation and higher NOx

Config. #2 CFD Results

*SAE 2001-01-0655**SAE 880423

Computed EquivalenceRatio Evolution



Computed EquivalenceRatio Evolution

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0 500 1000 1500 2000 2500 3000

Gas Temperature (K)

Equi

vale

nce

Rat

io

*SAE 2001-01-0655**SAE 880423

Soot*

NOx

Ignition ZoneIdeal MixingLine

Soot**

Adiabatic Combustion Line


Config. #3 CFD Results



Impact of IncreasedInjection Pressure

84

85

86

87

88

89

90

91

92

93

94

95

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4

Smoke (FSN)

Nois

e (d

BA)


2002 FIE






NOx Distribution60

0

800

1000

1200

1400

1600

1800

2000

2200

2400

2600

0 .0

0.6

1.3

1.9

2.5

3.2

3.8

4.5

5.1

5.7

6.4

7.0

7.6

8.2

8.9

9.5

10.2

Engine Speed (rpm)

BM

EP (b

ar)

600

800

1000

1200

1400

1600

1800

2000

2200

2400

2600

0.0

0.9

1.6

2.4

3.1

3.9

4.7

5.4

6.2

7.0

7.7

8.5

9.3

10.1

Engine Speed (rpm)

BM

EP (b

ar)

NOx < 0.2 g/mi2002 Engine Results New Engine Results



Conclusion for LD Example

• Higher injection pressure important for light duty application

- Achieve noise and smoke requirements at higher loadswithin emissions certification region

- Important in mode transition

- Important for power density growth

• Multiple injection characteristics extremely important.

• Optimizing a combustion recipe for a wide range of injection pressureneeded



Conclusions

• The Analysis Led Design Process in vital to match the right technologyto meet emissions standards and customer requirements.

• Analysis tools vital for down selection of technology.

• Calibrated modes are part of the deliverables to the engine platform teams.

• All engine development programs at Cummins uses the Analysis Led DesignProcess.

Documents

Analysis Led Design for Engine System Development to Meet US2010