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# Aerodynamics of automobiles

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### Aerodynamics of automobiles

1. 1. Aerodynamics of automobiles Presentation of Netta Laczkovics Budapest University of Technology and Economics Faculty of Mechanical Engineering Bsc Major in Industrial Product Design Engineering English for Transportation Engineers 2015
2. 2. Contents  Introduction- The purpose of aerodynamic analysis  Fundamentals of aerodynamics. Basic equations  Aerodynamics of automobiles  History of car body desing  Top drag coefficients of today  Conclusion  Sources
3. 3. Introduction The purpose of aerodynamic analysis is to optimize  consumption  acceleration  maximum speed  emission  comfort  noise level  stability (controllability, directional control, side-wind sensitivity)  contamination of the body  cooling of the brakes and the engine
4. 4. Fundamentals of aerodynamics If the streamlines are curved pressure increases perpendicular to them, outwards from the centre of curvature 2 p v n R     n: co-ordinate normal to streamline R: radius of streamline curvature where
5. 5. Fundamentals of aerodynamics D D F C v A 2     Acting forces DC : Drag coefficient Drag force [N] Density [kg/m3] Velocity [m/s] Cross section area [m2] DF : : v : A:
6. 6. Basic equations Acting forces 2 ' p f A A F v C dA C e dA 2                p 2 p p C v 2       ' 0 f 2 C v 2       ' p fF f ,v,A,C ,C  p ' f 3 C 1 C 0,01     DP F v  2 D DF v C A 2      Pressure coefficientpC : Skin friction coefficient ' fC : Power and maximum speed
7. 7. Boundary layer separation and separation bubbles Aerodynamics of automobiles
8. 8. Boundary layer separation, separation bubbles and vortexes Aerodynamics of automobiles
9. 9. Aerodynamics of automobiles Boundary layer separation, separation bubbles and vortexes
10. 10. Aerodynamics of automobiles Reduction of aerodynamic drag  Front  Windshield and A-pillars  Roof  Rear  Side Panels
11. 11. Aerodynamics of automobiles Reduction of aerodynamic drag Underbody Attachment –front spoiler - rear wing spoiler  Wheels 50% of the DC
12. 12. History of car body design I. Period: Adaptation of shapes from other fields 1900-1920 1914 – Zeppelin – Alfa Romeo 1913 – Boat – Audi Alpensieger 1899 – Torpedo
13. 13. History of car body design II. Period: Streamlining 1920-1970 - Adapting the resaults of airplane and airship development 1937 – Tatraplan 1933-Audi 2L and Daimler- Benz 200 Cars based on Pál Járay’s ideas
14. 14. History of car body design III. Period: Detail optimization 1970-1990 - Tiny changes that make significant resaults
15. 15. History of car body design IV. Period: Shape optimization 1990- today Designing car body close to the ideal shape, then trying to turn into real vehicle with the least changes possible Lexus LFA Coupe Alfa Romeo Brera
16. 16. History of car body design Lowering the drag coefficient
17. 17. History of car body design The first shape-optimized car Audi 100 with Cd 0.3 (1982- 1991)
18. 18. Top drag coefficients of today’s cars
19. 19. Today’s most aerodynamic cars in production Mercedes –Benz CLA with Cd 0.22 (2013- present)
20. 20. Today’s most aerodynamic cars in production Volkswagen XL1 with Cd 0.19 (2013- present)
21. 21. Conclusion  Drag coefficient depends on many different factors  There are basic principles to reduce aerodynamic drag  There is no one and only solution for optimization  Does not exsist one optimum car body shape  Can reach significant solutions with small changes  Interference occours by modifying In optimisation besides wind tunnel investigations numerical simulation of flow field (CFD) has become more and more important
22. 22. Sources http://www.ara.bme.hu/ http://www.car-engineer.com/mercedes-cla-is-the-most-aerodynamic- production-car-of-the-world/ http://motorburn.com/2014/01/12-of-the-most-aerodynamic-cars-in- production-right-now/ http://www.car-revs-daily.com/2014/10/28/2007-lexus-lf-a-roadster/ http://forums.vwvortex.com/showthread.php?7005928-Lost-in- Translation-Viable-concept-cars-that-failed-to- deliver&p=85925579&viewfull=1 http://en.wikipedia.org/wiki/Automobile_drag_coefficient http://www.gencoupe.com/general-discussion/224609-2015-gen-coupe- rumored-released-later-year.html https://gr8autotech.wordpress.com/2013/06/16/vehicular-aerodynamics/ http://www.kasravi.com/cmu/tec452/aerodynamics/vehicleaero.htm
23. 23. Thank you for your attention! Any question?