GT Power simulations on a small two-stage turbocharged engine · TWO-STAGE ENGINE October 10, 2005...

• RENAULT Powertrain Division

GT Power simulations on a small twoGT Power simulations on a small two--stage stage turbocharged engineturbocharged engine

GT Power user conference - Frankfurt – October 2005

Alain LEFEBVRERENAULT POWERTRAIN DIVISION

LARDY TECHNICAL [email protected]

RENAULT

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE

RENAULT Powertrain division PresentationPresentation overviewoverview

Introduction•• Why a two-stage turbocharged engine ?

•• Engine and model description

Engine performances at full load•• Influence of the LP turbocharger on power•• Influence of the LP turbocharger on low end torque•• Influence of the LP turbocharger under transient conditions

Engine design at part load•• Calculation methodology•• Influence of the HP turbocharger on EGR rates

Conclusions


Use of a twoUse of a two--stage turbocharged enginestage turbocharged engine

GT Power user conference – Frankfurt – october 2005

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE

RENAULT Powertrain division ACEA agreements …ACEA agreements …

•• ACEA agreement : CO2 emissions should be reduced to140g/km in 2010120g/km in 2012

•• A way to reduce the engine consumption is to reduce the size of the engine. This solution is called downsizing

•• turbocharger is used to keep engine performances in spite ofa lower engine capacity under steady-state and transientconditions

•• two-stage turbocharging can be a response for the highdownsizing of a Diesel, already turbocharged engine

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE

RENAULT Powertrain division …… and and europeaneuropean normsnorms

•• Polluant emissions have been drastically reduced since the beginning of the 90’s and will have to be still reduced in the coming years

•• NOx emissions will have to be decreased

• One way to reduce NOx emissions is to increase the EGRrates

• two-stage turbocharging is one way to reach such highEGR levels

g/km

CO

HC+NOx

Soot

Euro 1(1993)

Euro 2(1996)

Euro 3(2000)

Euro 4(2005)

Euro 5(2008)

1 0.64 0.50

0.56

0.14

0.30

Euro 6(?)

PollutantEmissions

2.72 -82%

-69%-82%

NOx0.97 0.7

0.08 0.05 0.025

?0.50 0.250.50

0.25

0.005

0.20

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE

RENAULT Powertrain division

Small twoSmall two--stage enginestage enginetargettarget

TARGET

5

10

15

20

25

30

1000 1500 2000 2500 3000 3500 4000Engine speed (rpm)

BM

EP (b

ar)

TARGET

27

• RENAULT’s target : to reach 72kW/l and 220Nm/l with asmaller engine capacity (downsizing level=25%)

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



TARGET

5

10

15

20

25

30

1000 1500 2000 2500 3000 3500 4000Engine speed (rpm)

BM

EP (b

ar)

TARGET

72kW/l220Nm/l

27


A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE




•• To reach performances similar to the engine to replace, understeady and transient conditions, in spite of a lower enginecapacity and smaller turbochargers with lower turbine andcompressor efficiencies

TARGET

5

10

15

20

25

30

1000 1500 2000 2500 3000 3500 4000Engine speed (rpm)

BM

EP (b

ar)

TARGET

72kW/l220Nm/l

27

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE


Small twoSmall two--stage enginestage engineschematicschematic

CYL2 CYL3 CYL4CYL1

LPLPCOMPRESSOR COMPRESSOR

HP WGHP WG

INTAKE MANIFOLD

AIRAIRFILTERFILTER

LP WGLP WG

LP COOLER

EXHAUSTEXHAUST

exhaust gases

LPLPTURBINE TURBINE

HPHPCOMPRESSOR COMPRESSOR

HPHPTURBINE TURBINE

HP COOLER

•• Exhaust system in serial mode type

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE


Small twoSmall two--stage enginestage engineGT GT PowerPower modelmodel

HP turbine

HP compressor

TWO-STAGE ENGINE

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



HP turbine

HP compressor

LP turbine

LP compressor

TWO-STAGE ENGINE

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



HP turbine

HP compressor

LP turbine

LP compressor

Boostpressurecontrol

TWO-STAGE ENGINE

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



HP turbine

HP compressor

LP turbine

LP compressor

MaximumIn-cylinderpressurecontrol

TWO-STAGE ENGINE

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



•• GT Power model tuned at full load and steady state- pressure losses- combustion parameters- heat transfer coefficients (in-cylinder and exhaust)

•• Good agreement on the entire speed range and especiallyat low and high engine speeds

In-c

ylin

derp

ress

ure

(bar

)

Crank angle (°)

1250rpm

In-c

ylin

derp

ress

ure

(bar

)

Crank angle (°)

4000rpm


GT Power user conference – Frankfurt – october 2005

Full load simulationsFull load simulations


Full load simulations Full load simulations Influence of the LP turbocharger Influence of the LP turbocharger –– 4000rpm 4000rpm

GT Power user conference – Frankfurt – October 2005

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE


Influence of the LP turbine

47

52

57

62

67

72

2,8 3 3,2 3,4 3,6 3,8 4

Boost pressure (bar)

Spec

ific

pow

er (k

W/l)

Full load simulations at 4000rpmFull load simulations at 4000rpmInfluence Influence ofof thethe LP LP turbochargerturbocharger

Use Use ofof a a higherhigherLP LP turbochargerturbocharger

sizesize

72kW/l reached

•• maximum in-cylinder pressure = 180bar•• same air-fuel ratio

Increase inthe LP turbo

size

4000rpm

72

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



47

52

57

62

67

72

2,8 3 3,2 3,4 3,6 3,8 4


Spec

ific

pow

er (k

W/l)



sizesize

72kW/l reached

but at the price of highboost pressures


size

3.9b

ar

4000rpm

72

•• maximum in-cylinder pressure = 180bar•• same air-fuel ratio

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



3,5

4

4,5

5

5,5

6

6,5

7

7,5

8

2,8 3 3,2 3,4 3,6 3,8 4


Pres

sure

bef

ore

HP tu

rbin

e (b

ar)



sizesize

72kW/l reached


high pressure beforeturbine levels


size

3.9b

ar

4000rpm

6

7.5

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



-5,5

-5

-4,5

-4

-3,5

-3

-2,5

-22,8 3 3,2 3,4 3,6 3,8 4


PMEP

(bar

)



sizesize

72kW/l reached



High pumping losseslevels


size

3.9b

ar

4000rpm

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



255

260

265

270

275

280

285

290

2,8 3 3,2 3,4 3,6 3,8 4


BSF

C (g

/kW

h)



sizesize

72kW/l reached



Penalty in specific fuelconsumption


size

3.9b

ar

263

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



65

66

67

68

69

70

2,8 3 3,2 3,4 3,6 3,8 4Boost pressure (bar)

LP T

urbi

ne e

ffici

ency

(%)


Increase inthe LP turbine size

Positive Positive effecteffect ofof a a higherhigher

LP LP turbochargerturbochargersizesize

due toLP turbine

efficiency…

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE


Positive Positive effecteffect ofof a a higherhigher

LP LP turbochargerturbochargersizesize

due toLP turbine

efficiency…

…and LP compressor

efficiencyimprovement



56

60

64

68

72

76

80


LP c

ompr

esso

r effi

cien

cy


65

66

67

68

69

70


LP T

urbi

ne e

ffici

ency

(%)

Increase inthe LP turbine size

Increase inthe LP turbo size



Full load simulations Full load simulations Influence of the LP turbocharger Influence of the LP turbocharger –– low endlow end

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE


Influence of the LP turbocharger

125

150

175

200

225

1000 1500 2000 2500 3000 3500 4000

Engine speed (rpm)

Spec

ific

torq

ue (N

m/l)

Full load simulations at low endFull load simulations at low endInfluence Influence ofof thethe LP LP turbochargerturbocharger

•• LP LP turbochargerturbocharger sizesize hashas alsoalso a a strongstrong effect on on thetheengineengine performances performances eveneven atat lowlow speedspeed

TARGET

TARGET

TARGET

Pcyl max = 180barSame air-fuel ratio

Same boost pressure

Increase inthe LP turbocharger

size

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE


Influence of the LP turbocharger

125

150

175

200

225

1000 1500 2000 2500 3000 3500 4000

Engine speed (rpm)

Spec

ific

torq

ue (N

m/l)

Full load simulations at low endFull load simulations at low endInfluence Influence ofof thethe LP LP turbochargerturbocharger

•• LP LP turbochargerturbocharger sizesize hashas alsoalso a a strongstrong effect on on thetheengineengine performances performances eveneven atat lowlow speedspeed

•• Target Target reachedreached on on thethe entireentire speed rangespeed range

TARGET

TARGET

TARGET

Pcyl max = 180barSame air-fuel ratio

Same boost pressure

Increase inthe LP turbocharger

size



Full load simulations Full load simulations Influence of the LP turbo Influence of the LP turbo –– transient conditionstransient conditions

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE


Transient simulationsTransient simulationsModellingModelling

•• GT Power model already tuned at full load and steady state•• Adapted according RENAULT’s experience under transientconditions :- combustion parameters- in-cylinder heat transfer coefficients

•• Vehicle model based on a LAGUNA 2 with the engine to replace (target engine)

Aerodynamicand rolling

forces

Vehicle

Ambiant conditions

WheelsRoad

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE


Tip-in from 1000rpm in 3rd gear

00,10,20,30,40,50,60,70,80,9

1

2,4 3,4 4,4 5,4 6,4 7,4

Time (s)

Acc

eler

atio

n / m

ax. a

ccel

.

Transient simulationsTransient simulationsInfluence Influence ofof thethe LP LP turbochargerturbocharger

•• TransientTransient performances performances measuredmeasured on a on a LagunaLaguna 2 2 vehiclevehicle withwithtargettarget engineengine on a on a tiptip--inin fromfrom 1000rpm in 3rd 1000rpm in 3rd geargear afterafter part part loadload conditions (constant conditions (constant vehiclevehicle speed)speed)

Laguna 2 with targetmeasured

Torque demand

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



00,10,20,30,40,50,60,70,80,9

1

2,4 3,4 4,4 5,4 6,4 7,4

Time (s)

Acc

eler

atio

n / m

ax. a

ccel

.


Laguna 2 with targetmeasuredcalculated

•• TransientTransient performances performances calculatedcalculated on a on a LagunaLaguna 2 2 vehiclevehicle withwithtargettarget engineengine on a on a tiptip--inin fromfrom 1000rpm in 3rd 1000rpm in 3rd geargear afterafter part part loadload conditions (constant conditions (constant vehiclevehicle speed)speed)

•• GoodGood agreementagreement betweenbetween calculationscalculations andand teststests

Torque demand

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



00,10,20,30,40,50,60,70,80,9

1

2,4 3,4 4,4 5,4 6,4 7,4

Time (s)

Acc

eler

atio

n / m

ax. a

ccel

.



90% of maximum torque



A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



00,10,20,30,40,50,60,70,80,9

1

2,4 3,4 4,4 5,4 6,4 7,4

Time (s)

Acc

eler

atio

n / m

ax. a

ccel

.




Response time



A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



00,10,20,30,40,50,60,70,80,9

1

2,4 3,4 4,4 5,4 6,4 7,4

Time (s)

Acc

eler

atio

n / m

ax. a

ccel

.




τ=4.7s



A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



00,10,20,30,40,50,60,70,80,9

1

2,4 3,4 4,4 5,4 6,4 7,4

Time (s)

Acce

lera

tion

/ max

. acc

el.


•• TheThe vehiclevehicle withwith thethe smallsmall twotwo--stagestage engineengine hashas a a similarsimilaraccelerationacceleration to to thethe targettarget engineengine withwith single single turbochargerturbocharger



τ=4.7s

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



00,10,20,30,40,50,60,70,80,9

1

2,4 3,4 4,4 5,4 6,4 7,4

Time (s)

Acce

lera

tion

/ max

. acc

el.



τ=4.7s


•• LP turbo LP turbo hashas a a strongstrong effecteffect on on thethe transienttransient performances performances

Increase inthe LP stage

size

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



00,10,20,30,40,50,60,70,80,9

1

2,4 3,4 4,4 5,4 6,4 7,4

Time (s)

Acce

lera

tion

/ max

. acc

el.




•• LP turbo LP turbo hashas a a strongstrong effecteffect on on thethe transienttransient performancesperformances•• 1717% on % on thethe responseresponse timetime betweenbetween thethe largerlarger LP turbo LP turbo (72kW/l) (72kW/l) andand thethe smallersmaller HP turbo (64kW/l)HP turbo (64kW/l)

17%

72kW/l64kW/l

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



00,10,20,30,40,50,60,70,80,9

1

2,4 3,4 4,4 5,4 6,4 7,4

Time (s)

Acce

lera

tion

/ max

. acc

el.




•• AdvantageAdvantage for for thethe LagunaLaguna 2 2 withwith thethe targettarget engineengine atat thethebeginningbeginning thanksthanks to to itsits capacitycapacity

25%

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



00,10,20,30,40,50,60,70,80,9

1

2,4 3,4 4,4 5,4 6,4 7,4

Time (s)

Acce

lera

tion

/ max

. acc

el.


25%



•• AtAt thethe beginningbeginning ofof thethe transienttransient, HP turbine , HP turbine isis mainlymainly usedused

HP turbine

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



00,10,20,30,40,50,60,70,80,9

1

2,4 3,4 4,4 5,4 6,4 7,4

Time (s)

Acce

lera

tion

/ max

. acc

el.


25%

HP turbine



•• AtAt thethe beginningbeginning ofof thethe transienttransient, HP turbine , HP turbine isis mainlymainly usedused•• LP turbine LP turbine hashas an an effecteffect onlyonly afterafter 2.5s, 2.5s, whenwhen thethe engineengine

reachesreaches 1600rpm1600rpm

HP + LP turbines

N=1600rpm

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



00,10,20,30,40,50,60,70,80,9

1

2,4 3,4 4,4 5,4 6,4 7,4

Time (s)

Acce

lera

tion

/ max

. acc

el.


25%

HP turbine HP + LP turbines

N=1600rpm



•• AtAt thethe beginningbeginning ofof thethe transienttransient, HP turbine , HP turbine isis mainlymainly usedused•• LP turbine LP turbine hashas an an effecteffect onlyonly afterafter 2.5s, 2.5s, whenwhen thethe engineengine

reachesreaches 1600rpm1600rpm change in change in slopeslope

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE


GT Power calculations show that :it is possible to reach the target engine performances with a

smaller two-stage engine under steady-state and transientconditions

Balance between low and high engine speeds has to befound especially for the LP turbocharger

The use of larger LP turbochargers has a negative impacteven on low end torque and on the vehicle accelerationunder transient conditions

On the contrary, the use of too small HP turbochargers willhave a negative influence on the power target (not presentedhere)

Full load simulationsFull load simulationsConclusionsConclusions

☺



Part load simulationsPart load simulations

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE


Part load simulationsPart load simulationsPrinciplePrinciple

•• Main engine parameters during tuningtuning teststests- HP boost pressure - LP boost pressure - EGR vane opening- A/F ratio…

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE




• Parameters to optimize- Polluant emissions (to minimise)- Specific fuel consumption (to minimise)

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

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•• GT Power calculationscalculations outputs - effective section and dimensions of the EGR circuit- maximum EGR rate available

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

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•• Operating points representative of the NMVEG cycle :1500rpm – BMEP=8bar1750rpm – BMEP=8bar

….

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE






•• Operating points representative of the NMVEG cycle :1500rpm – BMEP=8bar1750rpm – BMEP=8bar

….We decided to use the new GT Power DOE and DesignOptimizer tools

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE


Part load simulationsPart load simulationsModellingModelling

•• GT Power model already tuned at full load•• Adapted according RENAULT’s experience at part loadon engines with EGR :

- combustion parameters- in-cylinder heat exchanges coefficients

•• PID regulation on A/F ratio with BMEP targetA/F ratio limitation (smoke limit)

•• DOE model based on : - WG diameters (LP WG diameter, HP WG closed) : 5 positions- EGR vane diameter : 5 positions(no regulation on wastegates and vanes)

•• For each case (1500rpm –BMEP=8bar,…) : 25 cases

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE


Part load simulationsPart load simulations1500rpm1500rpm--BMEP=8barBMEP=8bar

LP wastegate (mm)0

510

EGR diameter (mm)

2015

10

BM

EP (b

ar)

02468

10

BMEP=8bar limit

EGR

dia

met

er(m

m)

LP wastegate (mm)0510

10

20

15

BMEP

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



LP wastegate (mm)0

510

EGR diameter (mm)

2015

10

BM

EP (b

ar)

02468

10

BMEP=8bar limit

EGR

dia

met

er(m

m)


10

20

15

EGR diameter (mm)10 15 20LP wastegate (mm)

010 5


0510

EGR

(%)

BMEP

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



LP wastegate (mm)0

510

EGR diameter (mm)

2015

10

BM

EP (b

ar)

02468

10

BMEP=8bar limit

EGR

dia

met

er(m

m)


10

20

15


010 5


0510EGR diameter (mm)10 15 20



010 5

EGR

(%) EG

R (%

)

BSFC

(g/kWh)B

SFC

(g/k

Wh)

BMEP

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



EGR vane opening

Increase in the EGR rate

Increase in the air mass flow

Increase in the BMEP thanks to air fuel ratio

Air fuel ratio limitation(BSFC and smoke limits)

Turbocharging system limits(WG closed)

Maximum EGR rateMaximum EGR rate

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



Optimisation resultsBase HP turbocharger

BMEP

N

EGR (%)

BSFC (g/kWh)

EGR diameter

233

15.2mm

38

8bar

1500rpm

A/F ratio 15.1

EGR vane opening







A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



Optimisation resultsBase HP turbocharger

BMEP

N

EGR (%)

BSFC (g/kWh)

EGR diameter

233

15.2mm

38

8bar

1500rpm

A/F ratio 15.1

☺ Close to the RENAULT Eu06 estimated target

EGR vane opening







A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



Operating points far away from the surgeline in the HP and LP

compressor maps☺

LP compressor map (zoom)

HP compressor map

1.26

0.0025


Part load simulationsPart load simulationsInfluence of the HP turbochargerInfluence of the HP turbocharger


A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE


BMEP

N

EGR (%)

BSFC (g/kWh)

EGR diameter

231

15.2mm

42

8bar

1500rpm

A/F ratio 15.1

Part load simulationsPart load simulationsInfluence Influence ofof thethe HP turbineHP turbine

Optimisation resultsLower HP turbocharger

(max. mass flow rate -10% at πt=2.5)

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE


BMEP

N

EGR (%)

BSFC (g/kWh)

EGR diameter

231

15.2mm

42

8bar

1500rpm

A/F ratio 15.1

+10%




A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE


BMEP

N

EGR (%)

BSFC (g/kWh)

EGR diameter

231

15.2mm

42

8bar

1500rpm

A/F ratio 15.1

BMEP

N

EGR (%)

BSFC (g/kWh)

EGR diameter

233

10.3mm

40

8bar

1500rpm

A/F ratio 15.1

+10%




Optimisation resultsVGT HP turbocharger


A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



BMEP

N

EGR (%)

BSFC (g/kWh)

EGR diameter

231

15.2mm

42

8bar

1500rpm

A/F ratio 15.1

BMEP

N

EGR (%)

BSFC (g/kWh)

EGR diameter

233

10.3mm

40

8bar

1500rpm

A/F ratio 15.1

+10% -3.4%





A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE





BMEP

N

EGR (%)

BSFC (g/kWh)

EGR diameter

231

15.2mm

42

8bar

1500rpm

A/F ratio 15.1



BMEP

N

EGR (%)

BSFC (g/kWh)

EGR diameter

233

10.3mm

40

8bar

1500rpm

A/F ratio 15.1

Interest to use a lower HP turbocharger (but compromise to find with the maximum power)

☺

+10% -3.4%

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE



BMEP

N

EGR (%)

BSFC (g/kWh)

EGR diameter

231

15.2mm

42

8bar

1500rpm

A/F ratio 15.1

BMEP

N

EGR (%)

BSFC (g/kWh)

EGR diameter

233

10.3mm

40

8bar

1500rpm

A/F ratio 15.1

Interest to use a lower HP turbocharger (but compromise to find with the maximum power)Limited interest of a VGT HP turbine, due to lowerturbo-charger efficiencies

☺

+10% -3.4%






ConclusionsConclusionsGT Power user conference – Frankfurt – October 2005

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE


•• GT Power calculations were used to optimize the enginedesign at full load

- to choose the turbocharger matching for HP and LP stages- to evaluate the response times under transient conditions- target engine performances can be reached with a smaller

two-stage engine

•• GT Power DOE tools were used to estimate the maximum EGR rates at part load

- DOE is a good tool to have quick estimations on a large field- new interpolation methods have to be developed- Two-stage turbocharged engine is a good way to reachhigh EGR rates and to reach our estimated targets for Eu06

- Interesting influence of the HP turbine effective area (like ona classical single-stage turbocharged engine)

- Poor impact of the VGT turbine on the EGR rates

•• Turbocharger matching is also compromise between part andfull load, like on a single stage engine

Small twoSmall two--stage enginestage engineConclusionsConclusions



Thank you for your attention…

…Your questions

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE


Part load simulationsPart load simulationsDOE DOE tooltool

Sometimes difficult to have a good fit with the availableinterpolation methods (simple + quartic resolution modelgenerally giving the best results)

EGR diameter (mm)10 15 20

BM

EP

(bar

)

EGR diameter (mm)

BM

EP

(bar)

8

6

4

2

10

8

6

4

2

10

7.75

8.25

12.5 17.5

Simple+quartic

1750rpm-8bar

A. LEFEBVRE

TWO-STAGE ENGINE

October 10, 2005

RENAULT, FRANCE


Part load simulationsPart load simulationsDOE DOE tooltool

Sometimes difficult to have a good fit with the availableinterpolation methods (simple + quartic resolution modelgenerally giving the best results)

But possibility to fix constraints on the BMEP in the DOE☺

EGR diameter (mm)10 15 20

BM

EP

(bar

)

EGR diameter (mm)

BM

EP

(bar)

7.75 ≤ BMEP ≤ 8.25bar8

6

4

2

10

8

6

4

2

10

7.75

8.25

12.5 17.5

max

imum

EG

R ra

te

1750rpm-8bar

GT Power simulations on a small two-stage turbocharged engine · TWO-STAGE ENGINE October 10, 2005...

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Transcript of GT Power simulations on a small two-stage turbocharged engine · TWO-STAGE ENGINE October 10, 2005...