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

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Agenda • Background• Motivation • Design Method• Simulation Methods and Assumptions• Grid Convergence Study• Results• Flow Visualization• Improved Understanding Through Issues

Raised By Simulation • Conclusion

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Background

• 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

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Motivation – Where to begin?

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Design Process

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State Needs

DefineSpecifications

GenerateConcepts

Evaluate & Select

DetailedDesign

Manufacture& Test

State Needs

DefineSpecifications

GenerateConcepts

Evaluate & Select

DetailedDesign

Manufacture& Test

Main Focus of Paper

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Concepts vs Designs

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Concepts

Designs

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Making Concepts ComparableGeometric 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°

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Ricardo WAVE and VECTIS Simulation Software

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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

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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

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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

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Inlet Box

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Grid Convergence Study Grid convergence studies• ASME, AIAA, and others require it. Good practice.

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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

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Results – Volumetric Efficiency

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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

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NAAD

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Results – Absolute Average Deviation of Volumetric Efficiency (II)

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Conical-Spline Intake Concept (With Straight Runners)

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Results – Improvements in Calibration Process and Radiated Sound

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Results – Choked Flow Insights and Post Diffuser Total Pressure Recovery

Diffuser Exit

•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

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Side Entry Intake Conical Intake

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Flow Visualization – Enhanced Understanding

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•Look at air and fuel cylinder to cylinder stealing

•Identify regions of pressure loss and flow separation

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Flow Visualization – Enhanced Understanding II

14,000 RPM

11,500 RPM

14,000 RPM

11,500 RPM

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Time Averaged Velocity – 14,000 RPM

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Velocity Normal to Plane – Time Averaged14,000 RPM

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Flow Visualization – Flow Dynamics Through Animation

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14,000 RPM 14,000 RPM

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ConclusionLooked 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

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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

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