Automotive aerodynamics

AUTOMOTIVEAERODYNAMICS

PRESENTED BY:PRASHANT SAHGALU.I.E.T C.S.J.M UNIVERSITYMECHANICAL (2k11)

What does Aerodynamics means?•Aerodynamics is the study of moving

gases (in this case air) over a body in motion, and how that air flow will affect the body’s movement through the flow.

BASIC PRINCIPLES TO AERODYNAMICSA. LIFTB. THRUSTC. WEIGHTD. DRAG

In an airplane, when:Drag = Thrust & Weight = Lift

the plane will fly STRAIGHT & LEVEL 

Aerodynamics History• Aerodynamics has played an important role in car racing

since the late 1960s, when introduction of the first inverted wings appeared in some formulas.

• After that time, improved wing systems taken from the aeronautic technology made leaps forward, improving consistently lap times, increasing cornering speeds and vehicle stability.

• With the introduction of the ground effect a few years later the vehicles used a third element (the under body) to produce down force, and hence improve the performances.

wing

wing

What’s it take to create lift?Air and motion.

How do we explain lift?Newton’s Laws of Motion and

Bernoulli’s Principal are used to explain lift.

The Bernoulli Effect:•If a fluid (gas or liquid) flows around an object at

different speeds, the slower moving fluid will exert more pressure than the faster moving fluid on the object.

Thrust•A force that moves an object (vehicle) through the air.•Thrust is generated by the engines of the aircraft or vehicle 

Thrust is used to overcome the drag of an airplane or car, and to overcome the weight of a rocket.

Weight•A force by which the Earth pulls an object towards its

centre.•Weight = (mass) x (acceleration due to gravity)Drag•Aerodynamic force that resists the motion of an object moving through a fluid (air and water are both fluids).

F=(1/2)CdDV2A

•Cd = Coefficient of Drag

•It is a measure of Aerodynamic Efficiency of an Automobile.

So how much Drag Coefficient does a car designer aim for? •VOLVO 960 (1970 – 1980)•Cd = 0.36

•VOLVO S80 (2007 – present)•Cd = 0.28

•TOYOTA PRIUS HYBRID (2013 – present)•Cd = 0.26

Reducing the Cd of the car by just 0.01 can result in a 0.09 kmpl increase in the fuel economy.

•FORMULA ONE•Cd = 0.70 ??

What is the down force ?•The term down force describes the downward pressure created by the aerodynamic characteristics of a car that allows it to travel faster through a corner by holding the car to the track or road surface. However it also inverses friction between the tires and the road surface, thus decreasing maximum velocity.

•It’s a force which arises due to the airflow over and below the car, which act vertically downward on the car.

•FORMULA ONE Cars are aerodynamically design to generate maximum downforce.

•High Downforce allows them to race at speed more than 321.9kmph.

Aerodynamic Devices Wings and Spoilers Diffuser

Barge Board

Aerodynamic Analysis in Automobiles

•Wind Tunnels

•Softwares (ANSYS, CATIA)

Here are things that can be done to reduce your vehicle's drag (air

resistance): 1.Make the shape of the car so that air flow together smoothly towards the end of the car

2.Reduce the frontal area of the car by minimizing the grill making sure that windscreen is as flat as possible.

3.Cover the wheels.

•Nissan Maxima 1998 before & after aerodynamics changes.

CONCLUSIONEarlier cars were poorly designed with heavy engines, protruding parts and box shapes due to which they consume large quantity of fuel and became unaffordable. All these factors lead to the development and need of aerodynamic in the design of an automobile. Now it would be fair to say that all most all cars are tested for getting the optimum aerodynamic configuration.