Presentation Transcript

1. ECN 3 Diesel Combustion Topic 2: Mixing/chemistry interaction SYNTHESIS José M. García Oliver CMT-UPVLC Ann Arbor, April4th 2014
2. ACKNOWLEDGEMENTS Organizers & contributors GillesBruneaux, Raúl Payri, LylePickett Unvisiblecontributors…
3. SPRAY COMBUSTION FROM ECN1 TO ECN3 EXPERIMENTS
4. SPRAY COMBUSTION FROM ECN1 TO ECN3 SIMULATIONS
5. ACHIEVEMENTS Extension of experimental DB informationwithInjectors/Techniques/Soot LOL ID extensivelyused New indicators (sr, FL) bring in new informationon TCI More validationfrommodellingisneeded Analysison OH*/OH Detailedanalysis of OH and CH2O fields Improvedanalysis of sootunder SA conditions
6. ID/LOL - EXPERIMENTS LOL shows a single trendwithsmalldifferencesamonginstitutions + lowuncertainty ID shows more scattering, withhighuncertaintywhenmeasuredwithpressuresignal Ignition Delay (All Data) Lift-off length (LOL)
7. ID/LOL - MODELLING Clear overestimation of ID, mainlyduetolimitations of thechemistrydescription More evidentwithwell-mixedmodels Betterprediction of LOL
8. ID/LOL - MODELLING Fuel injection pressure sweep Ignition delay and Lift-off have opposite trend as function of the injection pressure How do modelsexplaintheeffect of injectionpressureonignitiondelay?
9. ACHIEVEMENTS Extension of experimental DB informationwithInjectors/Techniques/Soot LOL ID extensivelyused New indicators (sr, FL) bring in new informationon TCI More validationfrommodellingisneeded Analysison OH*/OH Detailedanalysis of OH and CH2O fields Improvedanalysis of sootunder SA conditions
10. REACTIVE SPRAY TIP PENETRATION Global combustionindicator Good repeatability among institutions/injectors in the experiments More scattering when comparing modelling approaches EXPERIMENTS MODELLING
11. REACTIVE SPRAY TIP PENETRATION Reacting vs non-reacting Comparison with inert case is key issue for understanding Sr (see Bridge the gap on April 5th) Sr/Si should be further analyzed EXPERIMENTS MODELLING
12. STABILIZED FLAME LENGTH Experimental definition + Scalinglaw StabilizedFlameLengthis a combustionindicatorthatcontainsbothmixing and combustion-relatedinfo Combustion-related mixing CMT 675 - Spray A - 15% O2 CFD VALIDATION?
13. ACHIEVEMENTS Extension of experimental DB informationwithInjectors/Techniques/Soot LOL ID extensivelyused New indicators (sr, FL) bring in new informationon TCI More validationfrommodellingisneeded Analysison OH*/OH Detailedanalysis of OH and CH2O fields Improvedanalysis of sootunder SA conditions
14. OH LIF vs OH* chem Experimental LOL Fairagreement in LOL betweenbothresultsalthoughwithinconsistencies Can this be standardized?
15. OH vs OH* Is it possible to use a LOL definition based on OH*? POLIMI - AR OHOH* Howreliable are OH* predictionsbythesimulation Trend seems to captured despite the very low values. A different threshold would be needed to be consistent with the OH based definition.
16. ACHIEVEMENTS Extension of experimental DB informationwithInjectors/Techniques/Soot LOL ID extensivelyused New indicators (sr, FL) bring in new informationon TCI More validationfrommodellingisneeded Analysison OH*/OH Detailedanalysis of OH and CH2O fields Improvedanalysis of sootunder SA conditions
17. FLAME STRUCTURE EXPERIMENTS + MODELING Detailedanalysis of flameevolution: OH, CH2O Interestingsimilarities in spite of thedifferences in startingconditions Stage I (around 0.6 ms) : CH2O@ 0.4ms
18. FLAME STRUCTURE EXPERIMENTS + MODELING Detailedanalysis of flameevolution: OH, CH2O Interestingsimilarities in spite of thedifferences in startingconditions Stage I (around 0.6 ms) : OH@ 0.55ms
19. FLAME STRUCTURE EXPERIMENTS + MODELING Deeperunderstanding of flowstructureevolutionalongdifferentstagesbycomparingbothpredictions and experimentsrelating Reactive penetration Velocity/densityfields Towhichextent are differences in local flowduetothe spray orthe TCI models?
20. ACHIEVEMENTS Extension of experimental DB informationwithInjectors/Techniques/Soot LOL ID extensivelyused New indicators (sr, FL) bring in new informationon TCI More validationfrommodellingisneeded Analysison OH*/OH Detailedanalysis of OH and CH2O fields Improvedanalysis of sootunder SA conditions
21. SOOT Experiment: KL signal Simulation: SVF Qualitativeagrement, furtherworkisneeded Whichdifferences are duetocombustionmodel? 1.5 ms 2 ms 2.5 ms
22. SOOT TOTAL SOOT MASS Onsetofsootformation Onset of sootdelayedwith ID Initialpeakduetotransient head, whyisitnotpredicted?
23. RECOMMENDATIONS FOR ECN3 SIMULATIONS A more accuratechemistrymodelisneeded Subtopicfor ECN4? Whynottesting spray A with a fuel with a betterknownchemistry, e.g. n-heptane? Well-mixedmodelissuelessaccuratepredictions of ID/LOL than TCI ones BUT more validationisneededtofullydiscernpredictioncapabilitiesregarding Velocityfield (PIV), FL, Penetration
24. RECOMMENDATIONS FOR ECN3 SIMULATIONS Inert vs reacting spray Alwayssimulateaninert case as a baselineuponwhichthereacting case can be compared This can rule outdifferencesdueto spray mixing Sootmodelsneedto be investigatedwith a closer look at thecombustionmodel LES contributions are welcome
25. RECOMMENDATIONS FOR ECN3 EXPERIMENTS Anytechniquethatdeliversinformationon local temperature/compositionunderreactingconditioniswelcome! More 2D Informationisessential More extensiveradiationmeasurements Closer look intosoot-radiationlink ANALYSIS FROM EXPERIMENTS+MODELLING Are weableto describe the spray flow time evolution?
26. RECOMMENDATIONS FOR ECN3 ADDITIONAL IDEAS AfterEOI flamedynamics DB extensionwithmultipleinjections/largerorificesize