FLUID DYNAMICS TRANSIENT RESPONSE … · 1910 16v jtd engine alfa romeo 147 vehicle transient simulation phases 1) the first phase is needed for identifying the initial steady-state

Frankfurt, 20 - 10 - 2003 Centro Ricerche Fiat is the sole owner of this document. It cannot be copied or given to third parties without permission.

GT-SUITE USERS CONFERENCE

FRANKFURT, OCTOBER 20TH 2003

FLUID DYNAMICS TRANSIENT RESPONSE

SIMULATION OF A VEHICLE EQUIPPED WITH A

TURBOCHARGED DIESEL ENGINE USING GT-POWER

TEAM OF WORK:

A. GALLONE, C. VENEZIAFIAT RESEARCH CENTRE

ENGINE ENGINEERING DIVISION

FLUIDS AND COMBUSTION ANALYSIS DEPARTMENTFrankfurt, 20 - 10 - 2003


PRESENTATION OVERVIEW

� INTRODUCTION

� GT-POWER MODEL DESCRIPTION

� STEADY STATE ANALYSIS – FULL LOAD CURVE

� TRANSIENT ANALYSIS

� TRANSIENT ANALYSIS: RESULTS WITH 2ND, 3RD, 4TH AND 5TH GEARS

� TRANSIENT ANALYSIS: PARAMETRIC EVALUATIONS

� REMARKS AND CONCLUSIONS

2


INTRODUCTION

THE IMPROVEMENT OF PASSENGER CARS EQUIPPED WITH TURBOCHARGED DIESEL

ENGINES HAS ASKED FOR A BETTER UNDERSTANDING AND OPTIMISATION OF THE FLUID

DYNAMICS PHENOMENA INVOLVED IN TURBO CHARGING.

AS WELL KNOWN, AN IMPORTANT EFFECT ON SUCH VEHICLE PERFORMANCE DURING

ACCELERATION PHASES IS DUE TO THE SO-CALLED “TURBOLAG”, THE ENGINE DELAY TO

A DRIVER’S REQUEST OF TORQUE.

USING THE 1D GT-POWER CODE VARIOUS TRANSIENT PHASES HAVE BEEN SIMULATED FOR

AN ALFA ROMEO 147 VEHICLE WITH 1.9 JTD ENGINE WITH A VGT TURBOCHARGER,

DURING ACCELERATIONS FROM 1000 ERPM TO 4500 ERPM WITH 2ND, 3RD, 4TH AND 5TH

GEARS.

THE CONTROL OF THE VARIABLE GEOMETRY TURBINE HAS BEEN IMPLEMENTED IN THE

MODEL USING GT-POWER CONTROL OBJECTS ONLY, IN ORDER TO KEEP THE SET-UP AS

EASY AS POSSIBLE. THE IMPLEMENTED CONTROL REPRODUCES THE REAL ECU STRATEGY.

3


INTRODUCTION

THE SIMULATION RESULTS, IN TERMS OF ENGINE TORQUE, VEHICLE SPEED, ETC, HAVE

BEEN COMPARED WITH VEHICLE EXPERIMENTAL DATA, PROVIDED BY FGP ITALY, AND THE

AGREEMENT IS SATISFACTORY.

AS RESULT, THE ACTIVITY HAS SHOWN THE KEY ROLE PLAYED BY THE TURBOCHARGER

INERTIA.

AFTER THIS FIRST STEP OF VALIDATION OF THE MODEL AND THE CONTROL

METHODOLOGY, A SERIES OF PARAMETRIC ANALYSES HAS BEEN PERFORMED.

THE EFFECT OF TURBOCHARGER INERTIA MANUFACTURE SCATTERING, FINAL DRIVE GEAR,

VEHICLE WEIGHT AND VOLUME DOWNSTREAM OF THE COMPRESSOR ON THE VEHICLE-

ENGINE SYSTEM BEHAVIOUR HAS BEEN EVALUATED.

4



INTRODUCTION

� GT-POWER MODEL DESCRIPTION






5


GT-POWER MODEL DESCRIPTION

INTAKE SYSTEM:

- AIR FILTER

- COMPRESSOR

- INTERCOOLER

- MANIFOLD

TURBOCHARGER

CONTROL

EXHAUST SYSTEM:

- MANIFOLD

- TURBINE

- EXHAUST NOZZLE

6



INTAKE SYSTEM:

- AIR FILTER

- COMPRESSOR

- INTERCOOLER

- MANIFOLD

TURBOCHARGER

CONTROL

EXHAUST SYSTEM:

- MANIFOLD

- TURBINE

- EXHAUST NOZZLE

7



INTAKE SYSTEM:

- AIR FILTER

- COMPRESSOR

- INTERCOOLER

- MANIFOLD

TURBOCHARGER

CONTROL

EXHAUST SYSTEM:

- MANIFOLD

- TURBINE

- EXHAUST NOZZLE

8



INTAKE SYSTEM:

- AIR FILTER

- COMPRESSOR

- INTERCOOLER

- MANIFOLD

TURBOCHARGER

CONTROL

EXHAUST SYSTEM:

- MANIFOLD

- TURBINE

- EXHAUST NOZZLE

9



INTAKE SYSTEM:

- AIR FILTER

- COMPRESSOR

- INTERCOOLER

- MANIFOLD

TURBOCHARGER

CONTROL

EXHAUST SYSTEM:

- MANIFOLD

- TURBINE

- EXHAUST NOZZLE

10



INTAKE SYSTEM:

- AIR FILTER

- COMPRESSOR

- INTERCOOLER

- MANIFOLD

TURBOCHARGER

CONTROL

EXHAUST SYSTEM:

- MANIFOLD

- TURBINE

- EXHAUST NOZZLE

11



INTAKE SYSTEM:

- AIR FILTER

- COMPRESSOR

- INTERCOOLER

- MANIFOLD

TURBOCHARGER

CONTROL

EXHAUST SYSTEM:

- MANIFOLD

- TURBINE

- EXHAUST NOZZLE

12



INTAKE SYSTEM:

- AIR FILTER

- COMPRESSOR

- INTERCOOLER

- MANIFOLD

TURBOCHARGER

CONTROL

EXHAUST SYSTEM:

- MANIFOLD

- TURBINE

- EXHAUST NOZZLE

13



INTRODUCTION







14


STEADY STATE ANALYSIS – FULL LOAD CURVE

GT-POWER MODEL VALIDATION WITH EXPERIMENTAL DATA

15

ENGINE M729 1910 16V JTD

0

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450

500

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500 1000 1500 2000 2500 3000 3500 4000 4500 5000

RPM

EXPERIMENTAL

GT-POWER



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500 1000 1500 2000 2500 3000 3500 4000 4500 5000

RPM

EXPERIMENTAL

GT-POWER




INTRODUCTION







16


TRANSIENT ANALYSIS

ADDITIONAL REQUIRED DATA FOR TRANSIENT ANALYSIS

1910 16V JTD ENGINE

ALFA ROMEO 147 VEHICLE

TRANSIENT SIMULATION PHASES1) THE FIRST PHASE IS NEEDED FOR IDENTIFYING THE INITIAL STEADY-STATE CONDITION

OF THE TRANSIENT. THIS MEANS THE CALCULATION OF THE FUEL REQUIRED FOR THE

BALANCE BETWEEN THE POWER SUPPLIED BY THE ENGINE AND WHAT REQUESTED BY THE

VEHICLE AT A GIVEN VEHICLE VELOCITY WITH FIXED GEAR.

2) THE SECOND PHASE IS THE PHYSICAL TRANSIENT: THE INPUT SIGNAL, CORRESPONDING

TO A FUEL STEP FROM PART LOAD TO FULL LOAD, IS APPLIED TO THE ENGINE AND THE

VEHICLE-ENGINE SYSTEM CHANGES DEPENDING ON ITS PHYSICAL LAWS.

- ENGINE INERTIA

- TURBOCHARGER INERTIA

- VEHICLE MASS

- FRONT AREA AND CX

- WHEELS INERTIA

- FINAL GEAR AND GEARS RATIOS

17


TURBOCHARGER CONTROL FOR TRANSIENT ANALYSIS

INTAKE SYSTEM:

- AIR FILTER

- COMPRESSOR

- INTERCOOLER

- MANIFOLD

TURBOCHARGER

CONTROL

EXHAUST SYSTEM:

- MANIFOLD

- TURBINE

- EXHAUST NOZZLE

18


TURBOCHARGER CONTROL FOR TRANSIENT ANALYSIS

1) A TURBINE RACK POSITION CONTROL IS NEEDED TO ADJUST THE BOOST PRESSURE

DURING THE TRANSIENT.

2) THE TURBINE RACK POSITION CONTROL STRATEGY DURING THE TRANSIENT IS THE

FOLLOWING: AT FIRST THE MOST CLOSED RACK POSITION IS EMPLOYED, AND THEN THE

FULL LOAD REGULATIONS ARE GRADUALLY USED NEAR THE TARGET BOOST PRESSURE

ACHIEVEMENT (THE PID CONTROL ADJUSTS ON STEADY-STATE MAP).

BOOST SENSOR

ENGINE RPM

SENSOR

RACK ACTUATOR

0.1 = MINIMUM TURBINE OPENING

1 = MAXIMUM TURBINE OPENING

PID

STEADY STATE RACK

SUM

LIMITER

19



INTRODUCTION



TRANSIENT ANALYSIS




20


TRANSIENT ANALYSIS: RESULTS II GEAR

BOOST PRESSURE: THE COMPARISON BETWEEN THE STEADY-STATE AND TRANSIENT

BOOST PRESSURES SHOWS THE ENGINE DELAY TO A DRIVER’S REQUEST OF TORQUE, DUE

TO THE SO-CALLED “TURBOLAG”.

ENGINE M729 1910 16V JTD - VEHICLE 147

1000

1500

2000

2500

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

RPM

STEADY-STATE

II GEAR

TURBOLAG

STEADY-STATE BOOST PRESSURE

TRANSIENT BOOST PRESSURE

21




1000

1500

2000

2500

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

RPM

-0.2-0.10.00.10.20.30.40.50.60.70.80.91.01.11.21.3

STEADY-STATE

II GEAR

PID RACK

STEADY-STATE RACK

ACTUATOR RACK

PID RACK

STEADY-STATE RACK

ACTUATOR RACK

TURBOLAG

ENGINE M729 1910 16V JTD – VEHICLE 147

CONTROL STRATEGY: THE PID CONTROL (PID RACK) ADJUSTS TO GET THE TARGET BOOST

PRESSURE (STEADY-STATE BOOST PRESSURE) WORKING ON STEADY-STATE MAP

(STEADY-STATE RACK). THE RESULTANT SIGNAL (ACTUATOR RACK) OPERATES ON THE

TURBINE RACK POSITION. THE GRADUAL ADJUSTEMENT OF THE ACTUATOR RACK AVOIDS

THE OVERBOOST PRESSURE AND ITS OSCILLATIONS.

22



23


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200

250

300

350

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

RPM

STEADY-STATE

II GEAR


THE EXPERIMENTAL VEHICLE TORQUE IS DERIVED FROM ACCELERATION MEASUREMENTS,

SOLVING THE MOTION EQUATION.

EXPERIMENTAL RESULTS

GT-POWER RESULTS




0

50000

100000

150000

200000

250000

300000

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

RPM

0.00.20.40.60.81.01.21.41.61.82.02.22.42.62.83.0

STEADY-STATE

II GEAR

TURBOCHARGER SPEED

TURBINE EXPANSION RATIO

THE TURBOLAG PHENOMENON IS MAINLY RELATED TO THE TURBOCHARGER INERTIA.

THE GRADUAL ADJUSTEMENT OF THE ACTUATOR RACK AVOIDS THE INCREASE OF

TURBINE EXPANSION RATIO ABOVE THE STEADY-STATE VALUES, LIMITING THE

OVERBOOST AND THE TURBOCHARGER OVERSPEED EFFECTS.

24



TYPICAL VEHICLE RESULTS ARE THE VEHICLE SPEED, VEHICLE ACCELERATION AND

VEHICLE JERK (ACCELERATION DERIVATIVE).


0

7

14

21

28

35

42

49

56

63

70

3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0

TIME [s]

-1.0

-0.4

0.2

0.8

1.4

2.0

2.6

3.2

3.8

4.4

5.0

II GEAR

VEHICLE ACCELERATION

VEHICLE JERK

VEHICLE SPEED

25


TRANSIENT ANALYSIS: RESULTS III GEAR


1000

1500

2000

2500

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

RPM

-0.2-0.10.00.10.20.30.40.50.60.70.80.91.01.11.21.3

STEADY-STATE

III GEAR

PID RACK

STEADY-STATE RACK

ACTUATOR RACK



26


TRANSIENT ANALYSIS: RESULTS III GEAR

GT-POWER RESULTS


50

100

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300

350

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

RPM

STEADY-STATE

III GEAR



27


TRANSIENT ANALYSIS: RESULTS IV GEAR


1000

1500

2000

2500

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

RPM

-0.2-0.10.00.10.20.30.40.50.60.70.80.91.01.11.21.3

STEADY-STATE

IV GEAR

PID RACK

STEADY-STATE RACK

ACTUATOR RACK



28


TRANSIENT ANALYSIS: RESULTS IV GEAR

29

THE CALCULATED TRANSIENT BOOST PRESSURE SHOWS A DELAY COMPARED TO

THE STEADY-STATE ONE.THE CALCULATED TRANSIENT TORQUE

REACHES THE STEADY-STATE VALUES IN ADVANCE FOR THE EMPLOYED COMBUSTION

MODEL (FULL LOAD COMBUSTIONS).

GT-POWER RESULTS


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350

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

RPM

0

1000

2000

3000

4000

5000

6000

STEADY-STATE

IV GEAR


ENGINE TORQUE




TRANSIENT ANALYSIS: RESULTS V GEAR


1000

1500

2000

2500

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

RPM

-0.2-0.10.00.10.20.30.40.50.60.70.80.91.01.11.21.3

STEADY-STATE

V GEAR

PID RACK

STEADY-STATE RACK

ACTUATOR RACK



30


TRANSIENT ANALYSIS: RESULTS V GEAR

31

THE CALCULATED TRANSIENT BOOST PRESSURE HAS NOT A DELAY COMPARED TO

THE STEADY-STATE ONE.THE CALCULATED TRANSIENT TORQUE

EXCEEDS THE STEADY-STATE VALUES FOR THE EMPLOYED COMBUSTION MODEL (FULL LOAD

COMBUSTIONS).

GT-POWER RESULTS


50

100

150

200

250

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500 1000 1500 2000 2500 3000 3500 4000 4500 5000

RPM

0

1000

2000

3000

4000

5000

6000

STEADY-STATE

V GEAR


ENGINE TORQUE




TRANSIENT ANALYSIS: RESULTS II, III, IV AND V GEARS

IN TERMS OF BOOST PRESSURE THE FLUID DYNAMICS EFFECT OF TURBOLAG IS

CORRECTLY CALCULATED BY THE CODE.


1000

1500

2000

2500

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

RPM

STEADY-STATEII GEARIII GEARIV GEARV GEAR

32


TRANSIENT ANALYSIS: RESULTS II, III, IV AND V GEARS

BASED ON ENGINE SPEED THE TURBOLAG

SEEMS TO BE GREATER FOR LOWER GEARS.

ACTUALLY THE TURBOLAG IN TERMS OF

TIME IS LONGER FOR THE HIGHER GEARS

BECAUSE THE ENGINE SPEED INCREASES

MORE SLOWLY.

500

1000

1500

2000

2500

3000

3500

4000

4500

0 5 10 15 20 25 30 35 40 45 50 55

TIME [s]


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RPM



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0 5 10 15 20 25 30 35 40 45 50 55

TIME [s]

II GEAR

III GEAR

IV GEAR

V GEAR

33



INTRODUCTION



TRANSIENT ANALYSIS

TRANSIENT ANALYSIS: RESULTS WITH 2ND, 3RD, 4TH AND 5TH GEARS



34


TRANSIENT ANALYSIS: PARAMETRIC EVALUATIONS

THE EFFECT OF THE FOLLOWING PARAMETERS ON THE MODEL HAS BEEN EVALUATED:

• TURBOCHARGER INERTIA WITH 2ND GEAR, ANALYSING A POSSIBLE MANUFACTURE

SCATTERING OF ± 5% AND ± 10% FOR THE SAME TURBOCHARGER.

• HIGH PRESSURE INTAKE SYSTEM VOLUME WITH 2ND GEAR, REDUCING THE LENGTH

OF THE PIPES BETWEEN COMPRESSOR AND INTERCOLER AND BETWEEN INTERCOOLER

AND INTAKE MANIFOLD (REDUCTION FROM 6.3 TO 4.3 LITRES OF HIGH PRESSURE

VOLUME).

• VEHICLE WEIGHT WITH 2ND, 3RD, 4TH AND 5TH GEARS, INCREASING ITS VALUE OF 200 KG.

• FINAL GEAR RATIO WITH 2ND, 3RD, 4TH AND 5TH GEARS, INCREASING ITS VALUE OF 10%.

35


TRANSIENT ANALYSIS: TURBOCHARGER INERTIA EFFECT

36


1000

1500

2000

2500

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

RPM



0

7

14

21

28

35

42

49

56

63

70

3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0

TIME [s]

-1.0

0.2

1.4

2.6

3.8

5.0

6.2

7.4

8.6

9.8

11.0II GEAR - TURBOCHARGER INERTIA BASELINEII GEAR - TURBOCHARGER INERTIA -5%II GEAR - TURBOCHARGER INERTIA +5%II GEAR - TURBOCHARGER INERTIA -10%II GEAR - TURBOCHARGER INERTIA +10%

VEHICLE SPEED VEHICLE ACCELERATION

VEHICLE JERK

THE TURBOCHARGER INERTIA EFFECT, DUE TO THE

MANUFACTURE SCATTERING, IS LIMITED IN TERMS OF

BOOST PRESSURE OR VEHICLE PERFORMANCE.


TRANSIENT ANALYSIS: HIGH PRESSURE VOLUME EFFECT

37


1000

1500

2000

2500

500 1000 1500 2000 2500 3000 3500 4000 4500 5000

RPM



50

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150

200

250

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500 1000 1500 2000 2500 3000 3500 4000 4500 5000

RPM

STEADY-STATE - VOLUME 6.3 l

STEADY-STATE - VOLUME 4.3 l

II GEAR - VOLUME 6.3 l

II GEAR - VOLUME 4.3 l

DURING TRANSIENT THE EFFECT OF HIGH

PRESSURE VOLUME REDUCTION (32%) IS

LIMITED IN TERMS OF BOOST PRESSURE.

IN STEADY-STATE CONDITION THE PIPES LENGTH

REDUCTION CHANGES THE BEHAVIOUR OF THE

VOLUMETRIC EFFICIENCY AND THEN THE ENGINE TORQUE.

THE TRANSIENT ENGINE TORQUE IS AFFECTED BY THE

STEADY-STATE CURVE.


TRANSIENT ANALYSIS: VEHICLE WEIGHT EFFECT

DURING TRANSIENT THE VEHICLE WEIGHT INCREASES THE ENGINE DELAY TO A DRIVER’S REQUEST OF TORQUE.


1000

1500

2000

2500

0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0

TIME [s]

II GEAR BASELINEIII GEAR BASELINEIV GEAR BASELINEV GEAR BASELINEII GEAR - WEIGHT + 200 KGIII GEAR - WEIGHT + 200 KGIV GEAR - WEIGHT + 200 KGV GEAR - WEIGHT + 200 KG

38


TRANSIENT ANALYSIS: FINAL GEAR RATIO EFFECT

DURING TRANSIENT THE VEHICLE FINAL GEAR RATIO INCREASES THE ENGINE DELAY TO A DRIVER’S REQUEST OF TORQUE.


1000

1500

2000

2500

0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0

TIME [s]

II GEAR BASELINEIII GEAR BASELINEIV GEAR BASELINEV GEAR BASELINEII GEAR - FINAL GEAR RATIO +10%III GEAR - FINAL GEAR RATIO +10%IV GEAR - FINAL GEAR RATIO +10%V GEAR - FINAL GEAR RATIO +10%

39



INTRODUCTION



TRANSIENT ANALYSIS

TRANSIENT ANALYSIS: RESULTS WITH 2ND, 3RD, 4TH AND 5TH GEARS

TRANSIENT ANALYSIS: PARAMETRIC EVALUATIONS


40


TRANSIENT SIMULATION REMARKS

THE TRANSIENT SIMULATION REQUIRES A VERY GOOD AND DETAILED STEADY-STATE

MODEL.

THE SETTING OF THE CONTROL PARAMETERS (PID) HAS BEEN CARRIED OUT IN 2ND GEAR,

WHERE THE CONTROL HAS TO BE FASTER FOR THE HIGHER ENGINE-VEHICLE

ACCELERATION; THE DETECTED PARAMETERS DON’T CHANGE FOR THE SIMULATIONS

WITH THE OTHER GEARS.

THE PARAMETRIC ANALYSIS FOR DIFFERENT GEARS IS VERY SIMPLE: IT IS ENOUGH TO

CHANGE THE GEAR NUMBER.

THE GT-POWER CALCULATION TIME ON PC (INTEL PENTIUM 4 - CPU 1500 MHZ) VARIES FROM

30 MINUTES (II GEAR) TO 90 MINUTES ABOUT (V GEAR) FOR THE ANALYZED

CONFIGURATION.

41


CONCLUSIONS

BY THE USE OF ONE DIMENSIONAL GT-POWER CODE IT IS POSSIBLE:

• TO ANALYZE ENGINE-VEHICLE TRANSIENTS, ALSO CONSIDERING THE RESPONSE

DELAY FOR TURBOCHARGED ENGINES, DUE TO THE TURBOLAG EFFECT.

• TO STUDY THE PERFORMANCE SUPPLIED BY THE ENGINE-VEHICLE SYSTEM FOR

DIFFERENT ENGINE OR VEHICLE PARAMETERS.

BY THIS CALCULATION METHODOLOGY IT IS POSSIBLE TO DEFINE THE BEST FLUID

DYNAMICS LAYOUT FOR THE INTAKE AND EXHAUST MANIFOLDS AND TURBOCHARGER

TYPE FOR TURBOCHARGED ENGINES, EVALUATING THE STEADY-STATE AND TRANSIENT

PERFORMANCE.

42


ACKNOWLEDGEMENTS

THE AUTHORS WISH TO THANK GAMMA TECHNOLOGIES INC., FOR THE SUPPORT PROVIDED

CONCERNING THE GT-POWER CODE AND, IN PARTICULAR, TO JOHN WILKEN FOR HIS

HELPFUL SUGGESTIONS.

FINALLY A SPECIAL THANK IS DUE TO LUIGI PILO (FGP - ITALY) FOR PROVIDING THE

VEHICLE EXPERIMENTAL DATA AND TO MARCO TONETTI (CRF) FOR HIS SUGGESTIONS

ABOUT THE REAL CONTROL SYSTEM STRATEGY.

43

Documents

FLUID DYNAMICS TRANSIENT RESPONSE … · 1910 16v jtd engine alfa romeo 147 vehicle transient simulation phases 1) the first phase is needed for identifying the initial steady-state