Aerodynamics of automobilesPresentation of Netta Laczkovics
Budapest University of Technology and EconomicsFaculty of Mechanical Engineering Bsc
Major in Industrial Product Design Engineering
English for Transportation Engineers 2015
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
IntroductionThe 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
Fundamentals of aerodynamics
If the streamlines are curved pressure increases perpendicular to them, outwards from the centre of curvature
2p v
n R
n: co-ordinate normal to streamlineR: radius of streamline curvature where
Fundamentals of aerodynamics
DD
FC
v A2
Acting forces
DC : Drag coefficient
Drag force [N]
Density [kg/m3]
Velocity [m/s]
Cross section area [m2]
DF :
:v :A :
Basic equations
Acting forces
2 'p f
A A
F v C dA C e dA2
p2
ppC
v2
' 0f
2C
v2
'p fF f , v,A,C ,C p
'f
3 C 1
C 0,01
DP F v 2D DF v C A
2
Pressure coefficientpC : Skin friction coefficient'fC :
Power and maximum speed
Boundary layer separation and separation bubbles
Aerodynamics of automobiles
Boundary layer separation, separation bubbles and vortexes
Aerodynamics of automobiles
Aerodynamics of automobiles
Boundary layer separation, separation bubbles and vortexes
Aerodynamics of automobiles
Reduction of aerodynamic drag
Front
Windshield and A-pillars
Roof
Rear
Side Panels
Aerodynamics of automobiles
Reduction of aerodynamic drag
Underbody
Attachment –front spoiler
- rear wing spoiler
Wheels 50% of theDC
History of car body designI. Period: Adaptation of shapes from other fields 1900-1920
1914 – Zeppelin – Alfa Romeo
1913 – Boat – Audi Alpensieger
1899 – Torpedo
History of car body designII. Period: Streamlining 1920-1970 - Adapting the resaults of airplane and airship development
1937 – Tatraplan 1933-Audi 2L andDaimler- Benz 200
Cars based on Pál Járay’s ideas
History of car body designIII. Period: Detail optimization 1970-1990 - Tiny changes that make significant resaults
History of car body designIV. 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
History of car body designLowering the drag coefficient
History of car body design
The first shape-optimized car
Audi 100 with Cd 0.3 (1982- 1991)
Top drag coefficients of today’s cars
Today’s most aerodynamic cars in production
Mercedes –Benz CLA with Cd 0.22
(2013- present)
Today’s most aerodynamic cars in production
Volkswagen XL1 with Cd 0.19
(2013- present)
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
Sourceshttp://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=1http://en.wikipedia.org/wiki/Automobile_drag_coefficienthttp://www.gencoupe.com/general-discussion/224609-2015-gen-coupe-rumored-released-later-year.htmlhttps://gr8autotech.wordpress.com/2013/06/16/vehicular-aerodynamics/http://www.kasravi.com/cmu/tec452/aerodynamics/vehicleaero.htm
Thank you for your attention!
Any question?
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