1. Instituto Brasileiro de Petróleo e Gás UniversityofBrighton Airflow and Fuel Spray Interaction in a Gasoline DI Engine Professor Morgan Heikal Internal Combustion Engines Group University of Brighton & Ricardo UK Ltd

2. 2 Presentation outline Area of Study Test Equipment and Methods Mie scatter studies Backlighting studies CFD analysis Results evaluation Conclusions

3. 3 Area of Study Airflow and Fuel Spray Interaction Early injection regimes Variation of spray characteristics with injection timing Distortion of fuel jet by air flow Comparison of experiment with CFD analysis To check on experimental findings

4. 4 Test Engine Ricardo ‘Hydra’ G-DI research engine Single-cylinder, wall-guided Full-quartz optical cylinder liner Heated Piston throttle intake plenum cam box cam pulleys cylinder head exhaust cylinder liner timing belt flywheel piston head piston extension

5. 5 Engine Combustion Chamber Top entry, pent roof construction Injector side mounted swirl atomiser 70 o included angle Spark Plug centrally located 2d piston profile 75mm stroke 74mm bore New diagram including piston profile and spark plug Get better image and re-do layout

6. 6 Optical Methods I Mie scatter 1000 rev/min, WOT, SOI ATDC 20, 40, 60 o

7. 7 Optical Methods II Backlighting studies 1000 rev/min WOT SOI ATDC 20, 40, 60 o

8. 8 CFD Analysis CFD Code  Ricardo VECTIS  Fuel spray model  Discrete droplet model (DDM)  Ensemble of droplet parcels  Introduction rate given by  injection rate  spray angle  droplet size distribution  Secondary break-up sub-models  Droplet turbulence interaction and impingement  Secondary break-up model – Reitz-Diwakar

9. 9 Mie Scatter Results I Raw average imageThresholded image Masked image

10. 10 Mie Scatter Results II Edge detection Injection progress

11. 11 Mie Scatter Results III SOI = 20 o ATDC SOI = 40 o ATDC SOI = 60 o ATDC SOI = 80 o ATDC

12. 12 Backlighting Results I Averaged image intake valves Edge detected intake valves

13. 13 Backlighting Results II Spray width intensity profile analysis 30 pixel 60 pixel 90 pixel 30 pixel 60 pixel 90 pixel

14. 14 CFD Analysis I spray shadow central plane nd 2 air speed vapour air speed on valve CL

15. 15 CFD Analysis II Comparison of results of CFD analysis with experiment

16. 16 CFD Comparison with Experiment SOI 60 o CA 8 o ASOI SOI 60 o CA 21 o ASOI

17. 17 Intensity variation with SOI Analysis of Mie Scatter Data

18. 18 Backlighting evidence Average spray width at 3 depths For 1.2, 1.6, 2.0, 2.4, 2.9ms ASOI Width decreases with later SOI

19. 19 Comparison with CFD CFD nd 2 values Similar increase with SOI Similar fluctuations CFD Mie scatter CFD

20. 20 Intensity Increase with SOI Central plane intensity only Jet squeezed by incoming air from valves Plume shape changed Flattened in cross-tumble plane Broadened in tumble plane More fuel is maintained in central plane Due to increased valve lift and air flow with later SOI Could have been due to changes in droplet size Checked against Begg(2003) and eliminated

21. 21 Intensity Irregularity with SOI Comes from jet flapping Seen in vapour distribution Valid indicator for early stages Clearest visualisation

22. 22 Measured Jet flapping Video representation Jet flap at start As CFD image Despite average image Rotational oscillation? Takes fuel in and out of central plane Explains intensity fluctuation with SOI

23. 23 Backlighting Image Oscillation also seen in this plane

24. 24 Backlighting Image Oscillation also seen in this plane

25. 25 Conclusion For early injection, incoming air acts on fuel jet Air flow from two valves flatten jet Fuel squeezed towards central pane Effect increases with SOI delay Shows as increasing Mie signal coverage and intensity Due to increasing air flow as valve opening and piston speed increase Narrowing seen in other plane Fuel jet is deflected downwards Jet is seen to oscillate Visible from Mie and backlighting data perspective Manifests as irregularity in Mie signal through injection process CFD Analysis Confirms effect if air inflow on jet Predicts oscillation of jet Is in general good agreement with experiment Single plane data can be difficult to interpret

26. 26 Close Thank you for your attention! Any questions?