1. ECN 3 Diesel Combustion Topic 2: Mixing/chemistry interaction SYNTHESIS José M. García Oliver CMT-UPVLC Ann Arbor, April 4th 2014

2. ECN 3 – Synthesis of Topic 2 2 April 4 th 2014 ACKNOWLEDGEMENTS Organizers & contributors Gilles Bruneaux, Raúl Payri, Lyle Pickett Unvisible contributors… Michele Bardi Michelle Bolla Yuri Wright ETH-Zurich Huber Baya-Toda Louis-Marie Malbec IFPEN Olawole KutiKAUST Seong-Young LeeMTU Dan HaworthPenn St Gianluca D'ErricoPoli. di Milano Lyle Pickett Scott Skeen Sandia Maarten Meijer Bart Somers TU/e Evatt HawkesUNSW Hu WangUWisc

3. ECN 3 – Synthesis of Topic 2 3 April 4 th 2014 ECN1ECN2 -Standardization -Comparison among contributors -Standardization -Comparison among contributors -SA standard-SA + parametrics -Short/Long Injection -LOL, ID -2D: PIV, SVF SPRAY COMBUSTION FROM ECN1 TO ECN3 EXPERIMENTS

4. ECN 3 – Synthesis of Topic 2 4 April 4 th 2014 ECN1ECN2 -Comparison among models -n-heptane -SA + parametrics -Short Injection -LOL, ID -SVF (n-heptane) SPRAY COMBUSTION FROM ECN1 TO ECN3 SIMULATIONS

5. ECN 3 – Synthesis of Topic 2 5 April 4 th 2014 ACHIEVEMENTS Extension of experimental DB information with Injectors/Techniques/Soot – LOL ID extensively used New indicators (sr, FL) bring in new information on TCI – More validation from modelling is needed Analysis on OH*/OH Detailed analysis of OH and CH2O fields Improved analysis of soot under SA conditions

6. ECN 3 – Synthesis of Topic 2 6 April 4 th 2014 Ignition Delay (All Data)Lift-off length (LOL) ID/LOL - EXPERIMENTS LOL shows a single trend with small differences among institutions + low uncertainty ID shows more scattering, with high uncertainty when measured with pressure signal

7. ECN 3 – Synthesis of Topic 2 7 April 4 th 2014 Clear overestimation of ID, mainly due to limitations of the chemistry description – More evident with well-mixed models Better prediction of LOL ID/LOL - MODELLING

8. ECN 3 – Synthesis of Topic 2 8 April 4 th 2014 Fuel injection pressure sweep Ignition delay and Lift-off have opposite trend as function of the injection pressure ID/LOL - MODELLING How do models explain the effect of injection pressure on ignition delay?

9. ECN 3 – Synthesis of Topic 2 9 April 4 th 2014 ACHIEVEMENTS Extension of experimental DB information with Injectors/Techniques/Soot – LOL ID extensively used New indicators (sr, FL) bring in new information on TCI – More validation from modelling is needed Analysis on OH*/OH Detailed analysis of OH and CH2O fields Improved analysis of soot under SA conditions

10. ECN 3 – Synthesis of Topic 2 10 April 4 th 2014 REACTIVE SPRAY TIP PENETRATION Global combustion indicator Good repeatability among institutions/injectors in the experiments More scattering when comparing modelling approaches EXPERIMENTSMODELLING

11. ECN 3 – Synthesis of Topic 2 11 April 4 th 2014 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 EXPERIMENTSMODELLING

12. ECN 3 – Synthesis of Topic 2 12 April 4 th 2014 Experimental definition + Scaling law Stabilized Flame Length is a combustion indicator that contains both mixing and combustion-related info CMT 675 - Spray A - 15% O2 STABILIZED FLAME LENGTH mixing Combustion-related CFD VALIDATION?

13. ECN 3 – Synthesis of Topic 2 13 April 4 th 2014 ACHIEVEMENTS Extension of experimental DB information with Injectors/Techniques/Soot – LOL ID extensively used New indicators (sr, FL) bring in new information on TCI – More validation from modelling is needed Analysis on OH*/OH Detailed analysis of OH and CH2O fields Improved analysis of soot under SA conditions

14. ECN 3 – Synthesis of Topic 2 14 April 4 th 2014 Experimental LOL Fair agreement in LOL between both results although with inconsistencies Can this be standardized? OH LIF vs OH* chem

15. ECN 3 – Synthesis of Topic 2 15 April 4 th 2014 Is it possible to use a LOL definition based on OH*? POLIMI - AR OH OH* Trend seems to captured despite the very low values. A different threshold would be needed to be consistent with the OH based definition. OH vs OH* How reliable are OH* predictions by the simulation

16. ECN 3 – Synthesis of Topic 2 16 April 4 th 2014 ACHIEVEMENTS Extension of experimental DB information with Injectors/Techniques/Soot – LOL ID extensively used New indicators (sr, FL) bring in new information on TCI – More validation from modelling is needed Analysis on OH*/OH Detailed analysis of OH and CH2O fields Improved analysis of soot under SA conditions

17. ECN 3 – Synthesis of Topic 2 17 April 4 th 2014 FLAME STRUCTURE EXPERIMENTS + MODELING Detailed analysis of flame evolution: OH, CH2O – Interesting similarities in spite of the differences in starting conditions Stage I (around 0.6 ms) : CH2O @ 0.4ms

18. ECN 3 – Synthesis of Topic 2 18 April 4 th 2014 FLAME STRUCTURE EXPERIMENTS + MODELING Detailed analysis of flame evolution: OH, CH2O – Interesting similarities in spite of the differences in starting conditions Stage I (around 0.6 ms) : OH @ 0.55ms

19. ECN 3 – Synthesis of Topic 2 19 April 4 th 2014 FLAME STRUCTURE EXPERIMENTS + MODELING Deeper understanding of flow structure evolution along different stages by comparing both predictions and experiments relating – Reactive penetration – Velocity/density fields To which extent are differences in local flow due to the spray or the TCI models?

20. ECN 3 – Synthesis of Topic 2 20 April 4 th 2014 ACHIEVEMENTS Extension of experimental DB information with Injectors/Techniques/Soot – LOL ID extensively used New indicators (sr, FL) bring in new information on TCI – More validation from modelling is needed Analysis on OH*/OH Detailed analysis of OH and CH2O fields Improved analysis of soot under SA conditions

21. ECN 3 – Synthesis of Topic 2 21 April 4 th 2014 1.5 ms2 ms2.5 ms Experiment: KL signal Simulation: SVF SOOT Qualitative agrement, further work is needed Which differences are due to combustion model?

22. ECN 3 – Synthesis of Topic 2 22 April 4 th 2014 TOTAL SOOT MASS Onset of soot formation SOOT Onset of soot delayed with ID Initial peak due to transient head, why is it not predicted?

23. ECN 3 – Synthesis of Topic 2 23 April 4 th 2014 RECOMMENDATIONS FOR ECN  3 SIMULATIONS A more accurate chemistry model is needed – Subtopic for ECN4? – Why not testing spray A with a fuel with a better known chemistry, e.g. n-heptane? Well-mixed model issue less accurate predictions of ID/LOL than TCI ones BUT more validation is needed to fully discern prediction capabilities regarding – Velocity field (PIV), FL, Penetration

24. ECN 3 – Synthesis of Topic 2 24 April 4 th 2014 RECOMMENDATIONS FOR ECN  3 SIMULATIONS Inert vs reacting spray – Always simulate an inert case as a baseline upon which the reacting case can be compared – This can rule out differences due to spray mixing Soot models need to be investigated with a closer look at the combustion model LES contributions are welcome NOZZLE FLOWNEAR NOZZLE EVAPORATIVE SPRAY COMBUSTIONSOOT

25. ECN 3 – Synthesis of Topic 2 25 April 4 th 2014 RECOMMENDATIONS FOR ECN  3 EXPERIMENTS Any technique that delivers information on local temperature/composition under reacting condition is welcome! – More 2D Information is essential More extensive radiation measurements – Closer look into soot-radiation link ANALYSIS FROM EXPERIMENTS+MODELLING Are we able to describe the spray flow time evolution?

26. ECN 3 – Synthesis of Topic 2 26 April 4 th 2014 RECOMMENDATIONS FOR ECN  3 ADDITIONAL IDEAS After EOI flame dynamics DB extension with multiple injections/larger orifice size