drag

1. AERODYNAMICS IN CARS
By
Ravi malla thakuri
U11ME380
3nd Year
B.Tech (Mech)

2. INTRODUCTION
AERODYNAMICS :
Study of forces generated by motion of air on moving body.
CLASSIFACATION OF AERODYNAMICS :
external and internal, subsonic , supersonic , hypersonic
FIELDS OF APPLICATION :
aerospace engineering, design of automobiles , ships , civil
engineering , design of bridges etc.

3. AERODYNAMIC FORCES ON A BODY
LIFT
(DOWNFORCE)
DRAG
WEIGHT
THRUST

4. HISTORY OF EVOLUTION OF
AERODYNAMICS IN CARS
DESIGN¶S IN EARLY 20th CENTURY :
cars with low speeds, no aerodynamic problems.
CAR¶S IN THE EARLY 50s :
cars designed for big familys , complete negligence
of aerodynamics.
CARS AFTER 70s :
fuel crisis , need of economic designs , evolution of
aerodynamics.

8. WHY WE NEED TO IMPROVE
AERODYNAMICS IN CARS
SPEED
better aerodynamics higher will be the speeds.
FUEL EFFICIENCY
better aerodynamics , less work for engine.

9. FRONT END
FRONTAL PRESSURE
PRESSURE DIFFERENCE
MINIMISE FRONTALAREA
REDUCE cd

10. REAR END
REAR VACCUM
FLOW DETACHEMENT
TURBULANCE

11. AERODYNAMICS IN MCLAREN
F1
SPECIFICATIONS
FRONT END
REAR END
SCOOPS
WINGS Mclaren F1

12. AERODYNAMIC DEVICES
SPOILERS
NACA DUCTS
Increase rate of flow
To expose air to areas not exposed to
direct air flow.

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METHODS TO EVALUATE
AERODYNAMICS IN CARS
WIND TUNNELS
Research tool to study effect of air
moving over a solid object.
Trial and error process.
Special pressure paints for analysis.
Detailed analysis of air flow patterns.
Analyzing for the optimal design.

14. SOFTWARES
DEVELOPMENTS IN CAD
ANSYS, CATIA,ALIAS STUDIO
ANALYZE CHANGES DURING DESIGN
PHASE AND DEVELOPMENT
REDUCES TIME TO DEVELOP
OPTIMAL DESIGN
ABLE TO STUDY INDIVIDUAL
ELEMENTS, MORE EFFECTIVE

15. AERODYNAMIC IMPROVEMENTS IN THE
CAR THAT WE ALREADY OWN
Keep your vehicle washed and waxed
Remove mud flaps behind wheels
Place license plate out of air flow
Avoid roof-racks or carriers
Close windows, close sunroof

16. SCOOPS
ENGINE COOLING
INCREASES FLOW
RATE OF AIR

17. WINGS
PRODUCE DOWNFORCE
REDUCE DRAG

19. COEFFICIENT OF DRAG
Drag = 1/2xd x Cd x A Xv2
Measure of aerodynamic
efficiency.

20. Drag Reduction System
The Drag Reduction System (DRS) is
perhaps the most interesting of the
new Technical Regulations imposed on
Formula 1 in 2011. Its purpose? To
promote overtaking by counteracting
the loss of downforce incurred when
following another Formula 1 car. This is
acheived by reducing the following
car's aerodynamic drag by opening a
driver activated flap on the rear wing of
the car. The device opens an
adjustable flap on the rear wing of the
car (which when closed creates more
downforce for greater cornering) to
reduce downforce, thus giving a
pursuing car more speed and a greater
chance of overtaking a car in front.

21. Functional description
The horizontal elements of the rear wing
consist of the main plane and the flap. The
DRS allows the flap to lift a maximum of 50
mm from the fixed main plane. This reduces
opposition (drag) to airflow against the wing
and results in less downforce. In the absence
of significant lateral forces (straight line), less
downforce allows faster acceleration and
potential top speed, unless limited by the
top gear ratio and engine rev limiter.

22. Diffuser
A diffuser, in an automotive context, is a shaped section of
the car underbody which improves the
car's aerodynamic properties by enhancing the transition
between the high-velocity airflow underneath the car and the
much slower freestream airflow of the ambient atmosphere. It
works by providing a space for the underbody airflow to
decelerate and expand (in area, density remains constant at the
speeds that cars travel) so that it does not cause excessive flow
separation and drag, by providing a degree of "wake infill". The
diffuser itself accelerates the flow in front of it, which helps
generate downforce.

23. Operation
When a diffuser is used, the air flows into the
underbody from the front and sides of the
car, accelerates and reduces pressure. There is a
suction peak at the transition of the flat bottom
and diffuser. The diffuser then eases this high
velocity air back to normal velocity and also helps
fill in the area behind the car making the whole
underbody a more efficient downforce producing
device by reducing drag on the car and increasing
downforce. The diffuser also imparts upward
momentum to the air which further increases
downforce.