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Airflow and Fuel Spray Interaction in a Gasoline DI Engine

Airflow and Fuel Spray Interaction in a Gasoline DI Engine. Professor Morgan Heikal Internal Combustion Engines Group University of Brighton & Ricardo UK Ltd. Presentation outline. Area of Study Test Equipment and Methods Mie scatter studies Backlighting studies CFD analysis

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Airflow and Fuel Spray Interaction in a Gasoline DI Engine

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  1. Airflowand Fuel Spray Interaction in a Gasoline DI Engine Professor Morgan Heikal Internal Combustion Engines GroupUniversity of Brighton & Ricardo UK Ltd

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

  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. throttle intakeplenum cam box cam pulleys cylinder head exhaust cylinder liner timing belt flywheel pistonhead pistonextension Test Engine • Ricardo ‘Hydra’ G-DI research engine • Single-cylinder, wall-guided • Full-quartz optical cylinder liner • Heated Piston

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

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

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

  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. Raw average image • Thresholded image • Masked image Mie Scatter Results I

  10. Edge detection Injection progress Mie Scatter Results II

  11. SOI = 20oATDC • SOI = 40oATDC • SOI = 60oATDC • SOI = 80oATDC Mie Scatter Results III

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

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

  14. spray shadow • central plane • vapour • air speed • nd2 • air speed on valve CL CFD Analysis I

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

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

  17. IntensityvariationwithSOI Analysis of Mie Scatter Data

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

  19. Comparison with CFD • CFD nd2 values • Similar increase with SOI • Similar fluctuations CFD CFD Mie scatter

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

  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. Backlighting Image • Oscillation also seen in this plane

  24. Backlighting Image • Oscillation also seen in this plane

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

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