Fuel injection and combustion integrated simulation for a ... · CPV valve in the injector model can cause this delayed closure; a more fast valve closure and a more limited pressure

GT-Suite Users International ConferenceFrankfurt a.M., October 20th 2008Frankfurt a.M., October 20 2008

Fuel injection and combustion integrated Fuel injection and combustion integrated simulation for a marine dieselsimulation for a marine diesel engineenginegg

F. Millo,F. Millo, E. PautassoE. Pautasso, , S. ZancanaroS. Zancanaro (Politecnico di Torino, Italy)(Politecnico di Torino, Italy)

D. Delneri (D. Delneri (Wärtsilä S.p.A, Italy)

Presentation OverviewPresentation Overview

•• IntroductionIntroduction

•• Experimental setExperimental set--upup

•• Analysis of the injector modelAnalysis of the injector modely jy j

•• Analysis of the engine modelAnalysis of the engine model

•• Integrated analysis of the injection model with the Integrated analysis of the injection model with the engine modelengine model

•• ConclusionsConclusions

IntroductionIntroductionIn a previous study on a marine diesel engine* a DoE analysis


•• Experimental Experimental setset--upup

In a previous study on a marine diesel engine a DoE analysiswas carried out in order to evaluate the effects on fuelconsumption and NOx emissions of different combination ofcompression ratio, injection timing, injector nozzle holes size

•• Analysis of the Analysis of the Injector modelInjector model

•• Analysis of the Analysis of the

and number.

yyEngine modelEngine model

•• Integrated Integrated analysis of the analysis of the i j ti d li j ti d linjection model injection model with the with the W6L26B2 W6L26B2 engine modelengine model


* GT-User Conference 2006 ; SAE paper 2007-01-0670

IntroductionIntroductionSince the previous work demonstrated the good potential of the



Since the previous work demonstrated the good potential of thesimulation tool as far as the combustion process wasconcerned, a further investigation was carried out, in order toevaluate the impact on fuel consumption and emissions of



different injection cam profiles, by means of an integrated fuelinjection and combustion simulation.




Experimental setExperimental set--upupMAIN ENGINE FEATURES : Wärtsilä W6L26B2

Type Diesel, 4 stroke, 6 cylinders in line



Bore/Stroke 260 / 320 mmDisplacement 101 dm3

Compression Ratio 16 : 1


•• Analysis of the Analysis of the Propeller curve

Compression Ratio 16 : 1Maximum Power 340 kW/cyl at 1000 rpm

Maximum BMEP 24.3 bar


•• Integrated Integrated analysis of the analysis of the i j ti d li j ti d l

# Engine speed [rpm]

BMEP [bar]

Load [%]

Air System Single Stage Turbocharger with Fixed Geometry Turbine

d Aft l

injection model injection model with the with the W6L26B2 W6L26B2 engine modelengine model

1 1000 24.0 1002 947 21.5 85

3 906 19.9 75and Aftercooler

Valves 4 valves/cylinderCombustion chamber Quiescent

•• ConclusionsConclusions 4 794 15.2 50

5 629 9.5 25

Experimental setExperimental set--upup

MAIN INJECTION SYSTEM FEATURES

Injection type Unit pump injector

MAIN INJECTION SYSTEM FEATURES•• IntroductionIntroduction


Pump plunger diameter

24 mm

Pump displacement 14.3 cm3



Pump max. pressure 2000 barInjector nozzle holes 9




Injector componentsInjector components

MDV l

CPV valve

MDV valve•• IntroductionIntroduction




Pump



Injector



Injector modelInjector model

CPV & MDV Valves Injection Line•• IntroductionIntroduction


Pump Injector


•• Analysis of the Analysis of the Pump InjectoryyEngine modelEngine model



Injector modelInjector modelImposed in- Imposed discharge Injector model



cylinder pressureg

nozzle coefficient


•• Analysis of the Analysis of the yyEngine modelEngine model


Injection Injection velocityinjection model injection model

with the with the W6L26B2 W6L26B2 engine modelengine model

pressure Needle lift


Injector model refinementInjector model refinement

The comparison between simulated and experimental data was•• IntroductionIntroduction


The comparison between simulated and experimental data wasnot satisfactory at the beginning, with injection pressuredifferences of over 200 bar and unacceptable differences inneedle lift duration that required further model refinements



needle lift duration that required further model refinements.



Δp




The first step was to adjust the injection duration in order to fit•• IntroductionIntroduction


The first step was to adjust the injection duration in order to fitthe experimental needle lift, varying the duration of the initialand closing transient phases of the pump delivery, byadjusting the pre-stroke and the spill port opening



j g p p p p gparameters.




Needle lift adjustment

Injector model refinementInjector model refinementThen, the difference in the injection pressure was then



, j pattributed to an overestimate of the pump internal leakage.

By reducing the leakage between pump plunger and cylinderthe pressure rate a satisfactory agreement with the



the pressure rate a satisfactory agreement with theexperimental data was obtained.

QPumpyy

Engine modelEngine model


Pump plunger



Injection pressure profile

Moreover the pressure trend in the injection line after the




Moreover, the pressure trend in the injection line after theinjection phase was not properly captured.



•• Integrated Integrated analysis of the analysis of the i j ti d li j ti d linjection model injection model with the with the W6L26B2 W6L26B2 engine modelengine model Pressure decrease


Injector modelInjector modelThis behaviour was caused by a too slow closure of the Control



yPressure Valve (CPV) after the pump delivery phase that causedan excessive pressure drop in the injection line. Anoverestimation of the damping coefficient between the MDV and



CPV valve in the injector model can cause this delayed closure;a more fast valve closure and a more limited pressure drop in theline was the obtained by reducing the damping coefficient.yy



Baseline damping coefficientCPV displacement


Reduced damping coefficient


Valve closure


A di ti f th l l i th•• IntroductionIntroduction


A proper prediction of the pressure level in theinjection line was then achieved





Injection pressure profile

Injector modelInjector modelComparison between experimental and



Comparison between experimental and simulated data for the needle lift and injection

pressure profile•• Analysis of the Analysis of the



Load 100%











Load 85%











Load 75%




Injector modelInjector modelComparison between experimental andComparison between experimental and

simulated data for the needle lift and injection pressure profile





Load 50%





The engine modelavailable before thei t t d l i



integrated analysis wasbased on the use of animposed injected massand injection pressure


•• Analysis of the Analysis of the and injection pressureprofile (obtained fromexperiments), with apredictive DI-Jet model


•• Integrated Integrated analysis of the analysis of the i j ti d li j ti d l predictive DI-Jet model

for combustion andemissions prediction.



Engine modelEngine modelEngine modelImposed injection

fImposed injectedtotal fuel mass•• IntroductionIntroduction


pressure from exp. total fuel mass



•• Integrated Integrated analysis of the analysis of the i j ti d li j ti d l Mass flow rate

Cd calculated

Heat release rate In-cylinder pressureinjection model injection model with the with the W6L26B2 W6L26B2 engine modelengine model

y p


Engine modelEngine modelComparison between experimental and simulated data

(engine “stand alone” model)•• IntroductionIntroduction






Integrated analysisIntegrated analysis

In a integrated simulation the injection pressure profile isprovided by the detailed injection model, while the in-cylinderpressure profile is calculated by the code.



In this way, it is possible to predict the effects of injectionsystem geometry variations (e.g. the cam profile or the


•• Analysis of the Analysis of the nozzle hole diameter), avoiding the need for any simplifiedhypothesis.

M if th i j ti d l i l lib t d it i


•• Integrated Integrated analysis of the analysis of the i j ti d li j ti d l Moreover, if the injection model is properly calibrated, it is

possible to obtain the pressure profile in parts of the injectionsystem, where positioning a real pressure sensor would bevery difficult or even impossible


very difficult or even impossible.•• ConclusionsConclusions


P fil i t f th•• IntroductionIntroduction


Effects of injection system geometry variations

Pressure profile in parts of the injection system

where no exp. meas. are availble

PRESSURE

PRESSURE PROFILE IN THE NOZZLE SAC

PRESSURE PROFILE WITH

PRESSURE PROFILE WITH SLOW CAM


•• Analysis of the Analysis of the PRESSURE PROFILE IN

THE NOZZLE HOLDER (SENSOR

STANDARD CAM

SLOW CAMyyEngine modelEngine model

•• Integrated Integrated analysis of the analysis of the i j ti d li j ti d l (SENSOR

POSITION)injection model injection model with the with the W6L26B2 W6L26B2 engine modelengine model


W26 Injector modelW26 Engine model


W26 Injector modelW26 Engine model•• IntroductionIntroduction






Integrated analysisIntegrated analysisImposed discharge Integrated model



nozzle coefficient




Heat release rate In-cylinder pressureInjection pressureinjection model injection model with the with the W6L26B2 W6L26B2 engine modelengine model


Integrated analysis Integrated analysis –– model validationmodel validationComparison between experimental and simulated datap p

(integrated simulation)•• IntroductionIntroduction






Integrated analysis Integrated analysis –– model validationmodel validation





Stand alone engine model Integrated simulation




Comparison between experimental and simulated data for

Integrated analysis Integrated analysis –– model validationmodel validationComparison between experimental and simulated data for

different engine operating points

In-cylinder pressure profile Heat release rate



In-cylinder pressure profile Heat release rate•• Analysis of the Analysis of the




Load 100%





Comparison between experimental and simulated data for different engine operating points•• IntroductionIntroduction






Load 85%











Load 75%











Load 50%



Integrated analysis Integrated analysis –– model validationmodel validationComparison between experimental and simulated data for

NOx emissions at different operating points•• IntroductionIntroduction





200 ppm




Once validated, the integrated model was then used to predictthe effects produced by different injection system geometryconfigurations.


•• Experimental Experimental setset--upup configurations.

Afterwards, experimental tests were carried out in order tocheck the reliability of the model predictions.



Config. Inj. Cam SOI Inj. hole diameter

[‐] [‐] [° bTDC] [‐]


•• Integrated Integrated analysis of the analysis of the i j ti d li j ti d l 1 Standard +2 deg adv Baseline

2 Slow Baseline Baseline


3 Slow +2 deg adv ‐15 % (area)•• ConclusionsConclusions

Integrated analysisIntegrated analysisComparison between different cam profilesComparison between different cam profiles


•• Experimental Experimental setset--upup Standard inj. cam Slow inj. cam





Configuration 1 Configuration 2 & 3

Integrated analysisIntegrated analysisComparison between experimental and simulated data forComparison between experimental and simulated data for

different injection system configurations @950 rpm (load = 85%)



I j ti•• Analysis of the Analysis of the



Injection pressure




Configuration 1 Configuration 2





Injected fuel mass Maximum injection pressure•• Analysis of the Analysis of the Injector modelInjector model








In-cylinder maximum pressure Brake specific NOx•• Analysis of the Analysis of the Injector modelInjector model




ConclusionsConclusions

•• AA goodgood correlationcorrelation betweenbetween experimentalexperimental datadata andandsimulationsimulation resultsresults bothboth forfor thethe injectioninjection systemsystem modelmodel andandforfor thethe engineengine modelmodel couldcould bebe achievedachieved


•• Experimental Experimental setset--upup gg

•• TheThe simplicitysimplicity ofof integratingintegrating differentdifferent modelsmodels (i(i..ee.. engineengineandand fuelfuel injectioninjection modelsmodels inin anan single,single, fullyfully


•• Analysis of the Analysis of the comprehensivecomprehensive modelmodel allowedallowed anan easyeasy assemblyassembly andandintegrationintegration afterafter preliminarypreliminary validationsvalidations carriedcarried outout forfor thethesinglesingle partsparts



•• AnAn integratedintegrated simulationsimulation withwith aa detaileddetailed engineengine modelmodel andandaa detaileddetailed injectioninjection modelmodel provedproved toto bebe extremelyextremely helpfulhelpfulff thth ti i titi i ti ff thth h lh l ii ff


forfor thethe optimizationoptimization ofof thethe wholewhole engineengine performanceperformance•• ConclusionsConclusions

GT-Suite Users International ConferenceFrankfurt a.M., October 20th 2008Frankfurt a.M., October 20 2008

Fuel injection and combustion integrated Fuel injection and combustion integrated simulation for a marine dieselsimulation for a marine diesel engineenginegg

F. Millo,F. Millo, E. PautassoE. Pautasso, , S. ZancanaroS. Zancanaro (Politecnico di Torino, Italy)(Politecnico di Torino, Italy)

D. Delneri (D. Delneri (Wärtsilä S.p.A, Italy)

Documents

Fuel injection and combustion integrated simulation for a ... · CPV valve in the injector model can cause this delayed closure; a more fast valve closure and a more limited pressure