Investigation of Intake Concepts for a Formula SAE Four-Cylinder Engine Using 1D/3D (Ricardo WAVE-VECTIS) Coupled Modeli

1. Investigation of Intake Concepts for a Formula SAE Four-Cylinder Engine Using 1D/3D (Ricardo WAVE-VECTIS) Coupled Modeling Techniques Mark Claywell Donald Horkheimer Garrett Stockburger University of Minnesota

2. Agenda • Background • Motivation • Design Method • Simulation Methods and Assumptions • Grid Convergence Study • Results • Flow Visualization • Improved Understanding Through Issues Raised By Simulation • Conclusion 2006-01-3652

3. Student Design Competition Events in America, Australia, Brazil, Germany, Italy, Japan, United Kingdom 200+ Universities involved Team score based on sales presentation, cost report, design quality, acceleration time, fuel economy, skid-pad, auto-cross and endurance race University of Minnesota SAE Engine Yamaha YZF-R6, Four Cylinder, Four stroke 600cc Displacement 15,500 rpm redline Bore = 65.5mm, Stroke = 44.5mm 4-2-1 Exhaust Header Sequential Port Fuel Injection (student calibrated) DOHC, 4 valves per cylinder Compression Ratio = 12.4:1 Fuel – Gasoline, 100 Octane Background 2006-01-3652

4. Motivation – Where to begin? 2006-01-3652

5. Main Focus of Paper State Needs State Needs Define Specifications Define Specifications Generate Concepts Generate Concepts Evaluate & Select Evaluate & Select Detailed Design Detailed Design Manufacture & Test Manufacture & Test Design Process 2006-01-3652

6. Concepts vs Designs Concepts Designs 2006-01-3652

7. Making Concepts Comparable • Geometric Similarities • Inlet box to diffuser exit is identical • Restrictor geometry identical • Plenum volume kept constant • Runner length, diameter, and taper kept constant • Packaging bend angle held at 55°

8. Ricardo WAVE and VECTIS Simulation Software WAVE (1D) VECTIS (3D) • Intake to Tail-Pipe Engine Code • Easily provides realistic boundary conditions to CFD solver • Uses simple models to analyze complex problems • Provides actionable engine performance information • Quick simulation time • Off the shelf • Computational Fluid Dynamics (CFD) Code – More Accurate Flow Results • Integrated pre/post-processing and solver • Automatic mesh generator works with CAD derived geometry • Automotive specific solver modules • Easy to implement parallel solver • Off the shelf Guessing at CFD boundary conditions is no good! WAVE makes the use of VECTIS for intake design worthwhile No code coupling = Questionable fidelity 2006-01-3652

9. Why Not a Steady State CFD Approach? • Agreement between flow solutions is poor • Steady state cylinder balance didn’t match • Steady state didn’t result in shocks, unsteady did • Finding non-tuning design improvements with steady state CFD may still be possible 2006-01-3652

10. Inlet Box Simplifying Assumptions • Assumptions • WAVE-VECTIS junctions placed in 1D flow areas • No throttle body • No fuel spray particles in CFD domain • k-ε turbulence model 2006-01-3652

11. Grid Convergence Study • Grid convergence studies • ASME, AIAA, and others require it. Good practice. 2006-01-3652

12. Results – Total Volumetric Efficiency Predictions • Differences in total VE from concept to concept is small • VE curves can be made similar by varying intake dimensions 2006-01-3652

13. Results – Volumetric Efficiency 2006-01-3652

14. Results – Absolute Average Deviation of Volumetric Efficiency (I) • Total volumetric efficiency hides the superiority of the best intake concept • Individual cylinder to cylinder imbalance needs to be measured to identify best concept 2006-01-3652

15. Results – Absolute Average Deviation of Volumetric Efficiency (II) Conical-Spline Intake Concept (With Straight Runners) 2006-01-3652

16. Results – Improvements in Calibration Process and Radiated Sound 2006-01-3652

17. Results – Choked Flow Insights and Post Diffuser Total Pressure Recovery • Lower AAD results in more regular pressure pulses at throat and lower time of choked flow • Beyond a certain diffuser length/area ratio total pressure recovery is limited Diffuser Exit Side Entry Intake Conical Intake 2006-01-3652

18. Flow Visualization – Enhanced Understanding • Look at air and fuel cylinder to cylinder stealing • Identify regions of pressure loss and flow separation 2006-01-3652

19. Flow Visualization – Enhanced Understanding II 11,500 RPM 11,500 RPM 14,000 RPM 14,000 RPM

20. Time Averaged Velocity – 14,000 RPM

21. Velocity Normal to Plane – Time Averaged14,000 RPM

22. Flow Visualization – Flow Dynamics Through Animation 14,000 RPM 14,000 RPM 2006-01-3652

23. Conclusion • Looked at how plenum geometry determines performance using WAVE-VECTIS • Found grid convergence studies essential for good CFD • Conical intake stood out as best • Smallest cylinder to cylinder imbalance • Better AFR control and acoustic characteristics • Regular pressure pulses at throat reduce choked flow • Adding bent runners for realistic packaging hurt performance, but only slightly • Improved understanding of fluid flow and dynamics 2006-01-3652

24. Questions? • Acknowledgements • Ricardo Sponsorship and Support - Patrick Niven & Karl John • University of Minnesota Supercomputer Institute - Dr. H. Birali Runesha and Support Staff • University of Minnesota SAE Chapter - Dr. Patrick Starr and Dr. David Kittleson • Minnesota State University, Mankato - Dr. Bruce Jones 2006-01-3652