Boosting Small Engines to High Performance – Boosting Systems ...

22
Detroit, October 16-19, 2012 [email protected] Combustion Development Methodologies and Challenges for Smaller Boosted Engines H. Kleeberg, S. Bowyer, D. Tomazic (FEV, Inc.) J. Dohmen, C. Schernus, B. Haake (FEV GmbH) 18 th DEER Conference 2012

Transcript of Boosting Small Engines to High Performance – Boosting Systems ...

Detroit, October 16-19, 2012 [email protected]

Combustion Development Methodologies and Challenges for Smaller Boosted Engines

H. Kleeberg, S. Bowyer, D. Tomazic (FEV, Inc.) J. Dohmen, C. Schernus, B. Haake (FEV GmbH)

18th DEER Conference 2012

© by FEV – all rights reserved. Confidential – no passing on to third parties

Content

Introduction

Downsizing Challenges – Boosting – Oil Dilution – EGR

Summary

Kleeberg, DEER2012_FEV_BoostingSmallEngines.pptx, 2012-10-16 2

© by FEV – all rights reserved. Confidential – no passing on to third parties

Coping with CO2 targets: Load point shift by Downsizing

Ways of Downsizing: Smaller Displacement by Smaller cylinders Less cylinders

– 6 4 – 4 3 – 3 2 or 4 2 (e.g. Fiat Cinquecento)

Engines with less cylinders expected in many places City cars Compact cars … Full size + luxury vehicles: e.g. some V8 T/C 6-cyl.

Cutting cylinders will be applied more frequently

3 Kleeberg, DEER2012_FEV_BoostingSmallEngines.pptx, 2012-10-16

Introduction

© by FEV – all rights reserved. Confidential – no passing on to third parties

Downsized Engine Boosting Tool Chain

4 Kleeberg, DEER2012_FEV_BoostingSmallEngines.pptx, 2012-10-16

Downsizing Challenges: Boosting

© by FEV – all rights reserved. Confidential – no passing on to third parties

Boosting

Same torque & power, smaller displacement Similar amount of air per cycle

⇒ air density ↑

Single stage turbo with limited full load speed range

2-stage turbo or super-turbo enables larger spread from low-end to rated speed

5 Kleeberg, DEER2012_FEV_BoostingSmallEngines.pptx, 2012-10-16

Ref.: Schernus, Wedowski, Sauerstein et al., “Vehicle Demonstrator w/ 2-stage turbo SI engine”, GT-SUITE Conf. 2009

Downsizing Challenges: Boosting

© by FEV – all rights reserved. Confidential – no passing on to third parties

2-stage boosting ⇒ same wide-range torque and power from even smaller displacements

6 Kleeberg, DEER2012_FEV_BoostingSmallEngines.pptx, 2012-10-16

5

10

15

20

25

30

0 2000 4000 6000 8000

Scatter bandFEV

Engine Speed / rpm

BM

EP

/ ba

r

Target

GDI

PFI

Scatterband T/C-Engines 80 kW/l

100 kW/l

120 kW/l

Large Turbocharger = LP-Stage

compressor mass flow

com

pres

sor

pres

sure

rat

io

nTC = const.

surge line

choke line

large compressor

compressor mass flow

com

pres

sor

pres

sure

rat

io

nTC = const.

surge line

choke line

large compressor

Small Turbocharger =

HP-Stage

compressor mass flow

com

pres

sor

pres

sure

rat

io

nTC = const.

surgeline

chokeline

small compressor

compressor mass flow

com

pres

sor

pres

sure

rat

io

nTC = const.

surgeline

chokeline

small compressor

Downsizing Challenges: Boosting

© by FEV – all rights reserved. Confidential – no passing on to third parties

Boosting: Influence of cylinder number

7 Kleeberg, DEER2012_FEV_BoostingSmallEngines.pptx, 2012-10-16

90 180 270 360 450 540 6300,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

4,5

5,0

0

2

4

6

8

10

°Crank Angle

Val

ve L

ift /

mm

pcyl

pExh

pInt

Valv

e Li

ft / m

m

Example 1500 rpm 4-Cyl.

pExh < pInt → pExh > pInt

Downsizing Challenges: Boosting

© by FEV – all rights reserved. Confidential – no passing on to third parties

Boosting: Influence of cylinder number

8 Kleeberg, DEER2012_FEV_BoostingSmallEngines.pptx, 2012-10-16

3-Cylinder engine ideal for turbocharging ⇒ high scavenging potential ⇒ very low residual gas fraction ⇒ good for knock mitigation

90 180 270 360 450 540 6300,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

4,5

5,0

0

2

4

6

8

10

Pre

ssur

e / b

ar

°Crank Angle

90 180 270 360 450 540 6300,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

4,5

5,0

0

2

4

6

8

10

°Crank Angle

Val

ve L

ift /

mm

pcyl

pExh

pInt

pExh << pInt

Pre

ssur

e / b

ar

Valv

e Li

ft / m

m

Example 1500 rpm 3-Cyl. Example 1500 rpm 4-Cyl.

pExh < pInt → pExh > pInt

Downsizing Challenges: Boosting

© by FEV – all rights reserved. Confidential – no passing on to third parties

Boosting: Influence of cylinder number

Compressor loop of a 2-cylinder engine Less than 3 cylinders:

9

Discontinuous sequence of intake strokes

Turbo compressor operating point shifts toward surge in breathing pauses

Counteraction increasing intake volume delays response

Supercharger alternative solution for PR ≤ 2.5

Boosting small cylinder numbers requires special attention

Kleeberg, DEER2012_FEV_BoostingSmallEngines.pptx, 2012-10-16

Downsizing Challenges: Boosting

© by FEV – all rights reserved. Confidential – no passing on to third parties

Boosting: Turbo Maps Pressure pulsation of a 4 cylinder engine

10 Kleeberg, DEER2012_FEV_BoostingSmallEngines.pptx, 2012-10-16

0 180 360 540 720Crank Angle

Exha

ust G

as P

ress

ure

high energy content at pressure peaks Standard turbine measurement

Extrapolation of turbine operation

Extrapolation ⇒ simulation errors B

SFC

[ %

] 100

95

90

85

105

Mea

sure

men

t

Sim

ulat

ion

with

ext

rapo

latio

n

Simulation Results (here: @ low end torque)

Simulations play an important role in TC engine development

Proper input data required

Downsizing Challenges: Boosting

© by FEV – all rights reserved. Confidential – no passing on to third parties

Extended Turbine Mapping Toolkit

11 Kleeberg, DEER2012_FEV_BoostingSmallEngines.pptx, 2012-10-16

Compressor Closed Loop Turbine Dynamometer

Run Away Measurement TC Friction Testing

Downsizing Challenges: Boosting

© by FEV – all rights reserved. Confidential – no passing on to third parties

Boosting: Obtaining the right maps for simulation

Hot Gas Test Bench w/ Compressor Closed Loop (CCL) Benefits from CCL

12

CCL enables higher/lower inlet pressure CCL LP (low pressure):

– compressor inlet density ↓ – Less turbine power, p5/p6 ↓

CCL HP (high pressure): – compressor inlet density ↑ – More turbine power, p5/p6 ↑

Significant increase of p5/p6 range

Reliable data for predicting turbine power in pressure peaks (pulse turbocharging)

Kleeberg, DEER2012_FEV_BoostingSmallEngines.pptx, 2012-10-16

Special Turbocharger Measurement Techniques Example

�̇�𝑟𝑟𝑟

𝜼

CCL LP CCL HP

Downsizing Challenges: Boosting

Standard

∆PR * 5

© by FEV – all rights reserved. Confidential – no passing on to third parties

Extended Turbine Models for Reliable Performance Prediction in any Operation

13 Kleeberg, DEER2012_FEV_BoostingSmallEngines.pptx, 2012-10-16

Compressor Closed Loop Turbine Dynamometer

Run Away Measurement TC Friction Testing

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4

1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 turbine pressure ratio

redu

ced

mas

s flo

w /

kgK

0.5 /s

bar

Downsizing Challenges: Boosting

© by FEV – all rights reserved. Confidential – no passing on to third parties

Fuel Injection

Same torque & power, smaller displacement Similar amount of fuel per cycle

– Similar injection amount with same cylinder number – Larger injection amount with less cylinders

Fuel spray length / bore ↑ ⇒ risk of wall wetting – Oil dilution – HC and soot – Higher risk of pre-ignition from stripped fuel-oil droplets

Injection technology needs adaptation – Injection pressure – Multiple injections

Approach: Experimental and Computational Analysis and Experimental Validation

14 Kleeberg, DEER2012_FEV_BoostingSmallEngines.pptx, 2012-10-16

Downsizing Challenges: Fuel Injection & Oil dilution

© by FEV – all rights reserved. Confidential – no passing on to third parties

Charge Motion Design for heavily downsized gasoline engines

Charge motion must involve all of the charge to provide a homogenous mixture

15 Kleeberg, DEER2012_FEV_BoostingSmallEngines.pptx, 2012-10-16

GT² Base

Hig

her v

eloc

ities

Bet

ter c

onse

rvat

ion

Filling port concept High Tumble Concept

Downsizing Challenges: Charge Motion

© by FEV – all rights reserved. Confidential – no passing on to third parties

CFD Evaluation of Wall Wetting

16 Kleeberg, DEER2012_FEV_BoostingSmallEngines.pptx, 2012-10-16

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4Full Load @ 5000 rpm

Swirl Injector Multi Hole Injector

Weig

hted W

all C

onta

ct [-]

360 420 480 BDC 600 660 7200.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4Full Load @ 5000 rpm

Swirl Injector Multi Hole Injector

Weig

hted W

all C

ontac

t [-]

[°CA ATDC]

Liner

All Surfaces

Cylinder center line piston @ BDC

Valve center line

Swirl Injector

Multihole Injector

Downsizing Challenges: Fuel Injection & Oil dilution

© by FEV – all rights reserved. Confidential – no passing on to third parties

Injection and Oil Dilution

Standardized Test Procedure

17 Kleeberg, DEER2012_FEV_BoostingSmallEngines.pptx, 2012-10-16

Downsizing Challenges: Fuel Injection & Oil dilution

- Dilution analysis method: Gravimetry for Gasoline Fuels

- Operating duration: 1 h- Coolant temperature: 50 °C- Oil temperature: uncontrolled- Production PCV system- Oil/Fuel acc. to OEM specs

Oil Dilution

2500 rpm / BMEP = 10 bar

Oil

Dilu

tion

/ h [%

]

0

2

4

6

8

10

12

14

16

18

20

Rel. AFR [-]0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 1.10

Scatter bandFEV

B15004a

Lower limitSolenoid DI

Example DISI T/C Injector Type A High Penetration

Example DISI T/C Injector Type B Low Penetration

© by FEV – all rights reserved. Confidential – no passing on to third parties

Cooled EGR benefit

CR increase by 2 units and fuel consumption benefit of 5% possible n = 1500 1/min, IMEP = 35 bar, rel. AFR= 1.0, with scavenging, RON 95

18 Kleeberg, DEER2012_FEV_BoostingSmallEngines.pptx, 2012-10-16

0

10

20

30

4033.6 34.4

Peak Pressure Position / °CA ATDC

80

100

120

140

112119

Peak Pressure / bar

0

2

4

6

8

1.5

COV of IMEP / %

1.1

230

240

250

260

270262

247

ISFC / (g/kWh)

-5%

CR: 8 CR: 10 6% cooled EGR

CR: 8 CR: 10 6% cooled EGR

Downsizing Challenges: EGR

© by FEV – all rights reserved. Confidential – no passing on to third parties

Cooled HP/LP EGR

19 Kleeberg, DEER2012_FEV_BoostingSmallEngines.pptx, 2012-10-16

EGR & increased backpressure reduce volumetric efficiency

Higher boost pressure required

Higher turbine power required Higher backpressure: turbine power

Increase of ∆p ?

EAT / Routing ?

T2-max to be protected w/ EGR

5 6

1 2 3

4

Exhm

InmCm

TmpBack

Vol. Effic.

λ LPmHPm

Downsizing Challenges: EGR

© by FEV – all rights reserved. Confidential – no passing on to third parties

EGR = F.E. benefit for T/C GDI Map = example for turbocharged gasoline engine 2.0l class

20 Kleeberg, DEER2012_FEV_BoostingSmallEngines.pptx, 2012-10-16

BM

EP /

bar

Engine Speed / rpm

Target: knock reduction FC benefit Solution: Cooled external EGR Challenges: Interaction with scavenging (HP – EGR) Transient boosting affected by additional HP EGR volumes only LP solution if best low end torque demanded

rel. A/F-Ratio=1

Physical effect: Dethrottle engine Solution: Internal or external (uncooled) EGR Challenges: none (state of the art)

0.9

0.85 0.8

Physical effect: knock reduction + reduced enrichment Solution: Cooled external EGR (HP or LP) Challenges: EGR cooling capacity Transient boosting affected by additional HP EGR volumes

Downsizing Challenges: EGR

© by FEV – all rights reserved. Confidential – no passing on to third parties

Conclusion

Future improvement of Downsizing engines Further reduction in size

– Advanced boosting systems – Appropriate cylinder dimensions – Matched injection technology

Proper control of auto-ignition (pre-ignition, knock, HCCI/RCCI) – Cooled LP+HP EGR – Thermodynamic cycle

Thermal management Friction

21 Kleeberg, DEER2012_FEV_BoostingSmallEngines.pptx, 2012-10-16

DEER Conference, Detroit, October 16-19, 2012 [email protected]

Combustion Development Methodologies and Challenges for Smaller Boosted Engines

Thank you for your attention!

Questions?