Date post: | 30-May-2018 |
Category: |
Documents |
Upload: | vinu198500 |
View: | 218 times |
Download: | 0 times |
of 18
8/9/2019 Aerodynamics in Car.
1/18
Aerodynamics
Everything You Need to Know About
By Julien Versailles
8/9/2019 Aerodynamics in Car.
2/18
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
8/9/2019 Aerodynamics in Car.
3/18
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
8/9/2019 Aerodynamics in Car.
4/18
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
8/9/2019 Aerodynamics in Car.
5/18
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
8/9/2019 Aerodynamics in Car.
6/18
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
8/9/2019 Aerodynamics in Car.
7/18
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
8/9/2019 Aerodynamics in Car.
8/18
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
8/9/2019 Aerodynamics in Car.
9/18
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
8/9/2019 Aerodynamics in Car.
10/18
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
8/9/2019 Aerodynamics in Car.
11/18
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
8/9/2019 Aerodynamics in Car.
12/18
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
8/9/2019 Aerodynamics in Car.
13/18
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
8/9/2019 Aerodynamics in Car.
14/18
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
8/9/2019 Aerodynamics in Car.
15/18
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
8/9/2019 Aerodynamics in Car.
16/18
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
8/9/2019 Aerodynamics in Car.
17/18
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
8/9/2019 Aerodynamics in Car.
18/18
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