Final Preseantation
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Shell Eco-marathon GDP 2013
Rules and Regulations Aerodynamic Design
Alexandros Ioannou
Outline• Rules and Regulations– Importance– Enforcement– Key Rules
• Aerodynamics– Different forms of drag– Mach and Reynolds number– Optimisation of the top profile– Ground clearance– Wheel fairings– Future Work
Rules and Regulations
Introduction
• In all sports Rules and regulations are important especially in motor racing
Importance
• Influence the design of the car due to restrictions
• Must comply in order to participate in practice or attempts
Enforcement
• Can be found online• Created Excel with relevant rules under each
role for easy access• Booklet containing rules ready to hand• Periodic checks
Dimensions
• Height Track ratio max 1.25 • Track width: at least 500 mm• Wheelbase: at least 1000 mm.
Chassis Height
• Height Track width ratio: maximum 1.25 • Required lowering of floor by 113mm• Used uprights
Conclusion
• There will be tests at the event to verify the legality of the car
Aerodynamic Design
Introduction
• Aerodynamic drag accounts for around half of the total drag
• Area for most improvement• Minimise drag and neutral lift
Drag
• Two main sources:1.Skin
2.Pressure
Theoretical estimation
• Velocity 6.9 m/s• Mach number: 0.020- incompressible• Reynolds number 1.26 million based on 2.70m
length – turbulent (3000~5000)
Initial Design
• For top section symmetrical aerofoil, tear drop shaped, delay transition
• For side, truncated half tear drop shape• Initial estimation of drag coefficient 0.16
Optimisation of top section
• Used XFR5.• Validation: Tested numerous NACA aerofoils.
Results with 15% at 0 CL of experimental from ‘Theory of Sections’ at same Reynolds number
Optimisation of top section• Inputted chassis into software. • Iterative process. Used spline to create best
aerofoil that fit our chassisVersion Sectional CD
1 0.00714
2 0.00724
3 0.00811
Ground clearance
• For a length of 2.70m minimum ground clearance is 10.0cm. Final Design has 11.5cm
Wheel fairings
• Decrease tyre drag by around 50%• Same NACA 66-021 aerofoil for all fairings• What changed was length
Wheel fairings
• Final wheel fairings length
Future work
• Optimise top and side section using CFD and wind tunnel
• Optimise wheel fairing junctions. Minimise interference drag
• Investigate performance in side winds• Wheel discs instead of spokes• Optimise camber for zero lift
Summary
• Rules and Regulations– Importance– Enforcement– Key Rules
• Aerodynamics– Different forms of drag– Mach and Reynolds number– Optimisation of the top profile– Ground clearance– Wheel fairings– Future Work
References• Joseph Katz (2006). Race Car Aerodynamics: Design for
Speed. Cambridge: Bentley Publisher. P52.• Buchheim, R., Deutenbach, K.-R., Luckoff, H.-J. (1981).
Necessity and Premises for reducing the aerodynamic drag of future passenger cars.SAE paper 810 185, Detroit.
• R H Barnard (2009). Road Vehicle Aerodynamic Design: an Introduction. 3rd ed. Hertfordshire: MechAero Publishing. P35.
• Wolf-Heinrich Hucho (1987). Aerodynamics of Road Vehicles. London: Betterworth & Co. P129, 232.
• John D. Anderson, JR (2011). fundamentals of Aerodynamics. 5th ed. New York: McGraw Hill. P381.
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