aerodynamics in car

8/9/2019 Aerodynamics in Car.

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Aerodynamics

Everything You Need to Know About

By Julien Versailles


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What is it? The study of forces

and the resultingmotion of objects

through the air or

The study of theflow of air aroundand through an

object


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Drag A mechanical force caused by an object moving through a fluid (liquid or

gas) The solid body must be in contact with the fluid There must be motion between the object and the fluid It is a vector quantity having both a magnitude and direction acting in a

direction opposite to the moving object


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Lift and Downforce Lift is the force that directly

opposes the weight of anobject and holds it in the air Lift occurs when a solid

object turns a moving flow of

gas A negative lift causes

downforce, which is the forcethat acts to push an object

closer to the ground Lift and downforce are

basically the same except thatdownforce acts downward and

lift acts upward


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Airplanes For any airplane to fly,

you must lift the weight of the airplane

The airfoils (wings)generate most of the lift tohold the plane in the air

Jet engines or propellers provide the thrust to pushthe airplane forwardthrough the air


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Newtons 3rd Law For every action (force) in nature there is an equal and

opposite reaction helps to explain the generation of lift from an airplane wing

The air is deflected downward by the action of the wing,and in reaction the wing is pushed upward


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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

The object willthen be forcedtoward thefaster movingfluidThe wing of anairplane isshaped so thatthe air movingover the top of the wing moves

faster than theair beneath itSince the air

pressure under the wing isgreater than thatabove the wing,lift is produced


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Racecars The total aerodynamic

package of the racecar isemphasized now more thanever before

The focus of their efforts is

on the aerodynamic forces of downforce and drag

Downforce is necessary for maintaining speed throughthe corners

The efficient design of aground effects racecar is

based on a downforce/dragcompromise


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The Chassis The shape of the chassis is

similar to an upside downairfoil

The shape of the underbodycreates an area of low pressure between the bottom of the car and the racing surface

The shape of the chassis sucksthe car to road, which results in

higher cornering speeds


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Wings Airfoils or wings are

also used in the frontand rear of the car inan effort to generatemore downforce

The efficiency of awing is thedownforce/drag ratio


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The Front Wing Assembly The first part of the car to

meet the air mass The flow field here is

better than at other parts

of the car because the air here has been disturbedthe least

The wing is designed to produce downforce andguide the air as it movestoward the body and rear

of the car


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The Rear Wing Assembly

The turbulent air movingtoward the rear of the car will impact the efficiencyof the rear wing

The rear wing is not asaerodynamically efficientas the front wing, yet itmust generate more thantwice as much downforceto balance the car


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Streamlines of Road Cars As the air flows over the hood of a regular car, it's loses pressure, but

when it reaches the windscreen, it again comes up against a barrier,and briefly reaches a higher pressure

The higher-pressure area in front of the windscreen creates adownforce

As the higher-pressure air in front of the windscreen travels over thewindscreen, it accelerates, causing the pressure to drop

lower pressure literally lifts on the car's roof as the air passes over it


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The Underside of a Car The underside of the car is responsible for creating lift or

downforce If a car's front end is lower than the rear end, then the

widening gap between the underside and the road createsa vacuum, or low-pressure area, and therefore "suction"that equates to downforce


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Flow Detachment Once the air makes it's way to the rear window, the notch created by

the window dropping down to the trunk leaves a vacuum, or low pressure space that the air is not able to fill properly As a result, a continuous vacuum sucks in the opposite direction the resulting lower pressure creates lift that then acts upon the

surface area of the trunk


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Applying Aerodynamics To appreciate the importance of aerodynamics as applied to motor vehicles it must be realized

that, as driving speeds increase, the power needed to overcome air drag multiplies at a very rapidrate As an example, let us apply this formula to a car whose engine has to generate 18 HP to

overcome the air drag at 80 km/h The power needed to double the speed to 160 km is shown in the following example. This is

eight times the power needed to travel at 80 km If it were possible to reduce the drag by 25% we would need only 108 HP and fuel consumptionwould be about one-quarter less than what it was before

It is now obvious why the proper shaping and streamlining of a car pays very significantdividends at little extra cost


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Why You Need Aerodynamics Not only can better

aerodynamics helpimprove the speed of acar, but it can also better

the efficiency of a car Proper aerodynamicshaping, has been found to

be the most effective andleast costly method of increasing fuel economyand performance,especially at higher speeds


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Other Important Aspects of

Aerodynamics Automotive aerodynamics

also plays an important rolein other related areasincluding:

high-speed traction,

sensitivity to crosswinds,efficient cooling (engine,drive train, exhaust system,and brakes), keeping the

front windshield, thewindows, the mirrors and theheadlights clean, and last butnot least, reducing wind

noise to a minimum

aerodynamics in car

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