Investigation of Intake Concepts for a Formula SAE

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

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

Background • University of Minnesota SAE Engine 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 3 • • • Yamaha YZF-R 6, Four Cylinder, Four stroke 600 cc Displacement 15, 500 rpm redline Bore = 65. 5 mm, Stroke = 44. 5 mm 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 2006 -01 -3652

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

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

Concepts vs Designs Concepts Designs 6 2006 -01 -3652

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° 7

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

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 9 2006 -01 -3652

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

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

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 12 2006 -01 -3652

Results – Volumetric Efficiency 13 2006 -01 -3652

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 14 2006 -01 -3652

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

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

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 Side Entry Intake 17 Diffuser Exit Conical Intake 2006 -01 -3652

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

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

Time Averaged Velocity – 14, 000 RPM 20

Velocity Normal to Plane – Time Averaged 14, 000 RPM 21

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

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 23 2006 -01 -3652

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 24 2006 -01 -3652