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International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal,Volume 3, Issue 1, January 2013)
236
Analysis of NACA 2412 for Automobile Rear Spoiler UsingComposite Material
A. Sunanda1,M. Siva Nayak21Asst. prof, Department of Mechanical Engg., SNIST,Ghatkesar, Hyderabad.
2Asst Prof, Mechanical Engineering Department, Rise Groups Of Institution, Ongole.
Abstract-- The NACA 4digit series aerofoil shapes are
universally accepted standard designs generally used for wind
turbine blades, helicopter rotor blades and car spoilers. The
Design and Simulation of these complex shapes is a
challenging task for the manufacturing engineers. These
components need to be made of materials having high specific
strength and better fatigue properties. The composites with
sandwich construction fulfill the above requirements.
The main aim of the present investigation is to select the
best fiber orientation for the fabrication of automotive rear
spoiler. The Design FOIL software provides different shapes
of aerofoil from which NACA 2412 has been selected. The
spoiler is modeled using CATIA software and is analyzed for
the static deflection as well as harmonic analysis has been
done by using ANSYS for various orientations of the fiber.
The designed model has been compared with the values
obtained from the simulation values. This confirms the design
feasibility and software adoptability for the design of
sandwich aerofoil shapes.
Keywords-- Automobile Rear Spoiler, CATIA, Composite
Material, NACA, air foil
I.
INTRODUCTION
A car spoiler is a wing like accessory that is usually
attached to the rear end of the cars, or normally mounted on
top of a car's trunk or positioned under the front bumper.
While the rear spoiler is sometimes called 'wing', the
frontal car spoilers are also called 'air dam'. Car spoiler
dynamically improves the external beauty of the car
making the car stand out in a crowd, making it more trendy
and sporty. In automobile parlance, a spoiler is an
aerodynamic device that is attached to an automobile. The
intended function of this device is to 'spoil' unfavorable air
movement across a body of vehicle of some kind in motion.It is customary for racing and other high performance
sports cars to be fitted with spoilers. Nowadays-even
passenger vehicles use spoiler very commonly. To put it
more succinctly, a car spoiler improves the performance of
the car and even sometimes stimulates its resale value of
the car.
The next area for development was to manage the
airflow underneath the car; firstly this was done by using
suction fans in the 1970s, once again by Chevrolet -
Chaparral.
However this car was banned as the cornering speed
reached, up to 1.7g, were thought too dangerous. This wa
taken on by Lotus when in 1978 the Lotus 79 had a fully
shaped underbody to channel the airflow, this car was also
banned. Modern day Formula One cars can now reach
cornering speeds of up to 5g, even though there are very
strict restrictions in the guidelines. This shows how faautomotive aerodynamics have been improved.
The introduction of the car spoiler begins in the 1960s
when NASCAR automobiles still looked like what you
drove on the street. In 1966, the Dodge Charger had
flatter nose and a long, sloping roofline that seemed to
make the car unstable and lift at higher speeds. NASCAR
was petitioned and they allowed the Dodge teams to a piec
of metal about one-half to two inches high to the rea
decklid. This trapped air on the decklid and created dow
force to stabilize the car. It did not make the Dodge
standout car, but other manufacturers did see th
aerodynamic perk of adding something to the back of th
car to increase down force.
II.
BASIC FUNCTION OF SPOILER
The main function of a spoiler is diffusing the airflow
passing over and around a moving vehicle as it passes ove
the vehicle. This diffusion is accomplished by increasing
amounts of turbulence flowing over the shape, spoilin
the laminar flow and providing a cushion for the lamina
boundary layer often spoilers are added solely fo
appearance with no thought towards practical purpose.
An important principle in aerodynamics is Danie
Bernoulli's principle. It is this principle that says that wher
there is an increase in flow velocity of a gas there is a
decrease in pressure for a fixed volume. This is due toNewton, as he said that energy cannot be created o
destroyed. This theory is used extensively in aeronautica
applications. The shape of an aircraft wing causes the air t
flow faster over the top surface than the bottom one
Bernoullis principle says that this means there is a lowe
pressure on the top surface compared to the bottom surfac
and so this creates lift.
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International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal,Volume 3, Issue 1, January 2013)
237
However if the wing were turned upside down then the
resultant force would be downwards, this is called downforce and is useful in car design as it pushes the tires onto
the road giving more grip. The diagram below illustrates
the Bernoulli principle on an aircraft wing.
Fig 1 How Lift is created on an aircraft wing
Fig.2 Air foil
Over the whole of a cars body there are many different
areas of lift and down force created. When explaining drag
it was said that the air molecules slowed when approaching
the front grill and then accelerated over the top and sides of
the car. This means that when the air flows over the bonnet
of the car it will be accelerating and so at a lower pressure,
therefore a lift force is felt over the bonnet. The air then
meets the windscreen and this acts like a barrier, similar to
the front grill and so a small down force will be createdhere. The air then once again accelerates to create lift over
the roof of the car. For some vehicles the roof has a large
surface area and so a large lift force can be created. There
may also be down force created as the air flows underneath
the vehicle, if there is a narrow gap between the road and
the car the air is constricted and so has to accelerate,
creating suction to the road surface. These forces are
shown on the diagram below.
Fig.3 Forces created by airflow over a car body
III.
BENEFITS OF CAR SPOILERS
A spoiler is a flattish, slightly curved appendage on th
rear of the vehicle. Spoilers are found on racing cars an
high performance sports cars. They primarily reduce th
amounts of lift and drag a vehicle experiences and at highespeed the force of the wind pushes down on the spoile
adding additional traction for the tires. While most stoc
spoilers usually add no discernable performance, a racing
spoiler that is usually larger in size and more aerodynami
can add performance- especially at higher speeds.
Apart from contributing to the external appearance of the
car, the spoiler is very useful in making the car more fuel
efficient. This mechanical accessory can make the ca
stable on roads. Spoiler improves vehicle stability by
decreasing lift or decreasing drag that may caus
unpredictable handling in a car speed. Spoiler disrupts th
airflow going over a moving car thereby reducing th
amount of life naturally generated by the shape of the car
Spoiler accomplishes this feat by increasing the turbulence
flowing over the shape 'spoiling' the laminar flow an
providing a cushion for the laminar boundary layer.
Most of the time, the car spoiler is a styled piece o
fiberglass, which enhances the aerodynamics of the car
Due to increase in traction a car in motion brakes, turns an
accelerates with more stability. Drag increases as the spee
of the car increases. It can be seen that some spoilers ar
effective at very low speeds often generating excessiv
drag while some other spoilers can work pretty well at high
speeds. Some passenger cars can be seen equipped with
both front and rear spoilers. Front spoilers which are found
beneath the bumper are used to direct airflow away from
the tires to the under body. Rear spoilers help to modify thtransition in shape between the roof and the rear and the
trunk and the rear. This minimizes the turbulence at the rea
of the vehicle. Some rear spoilers come with a warning
brake light built into the spoiler.
IV.
CAR SPOILER TYPES
Spoiler wings come in various shapes and sizes and in
numerous designs. They could be high hopped, Supr
styled, Lip spoiler or wings wrest spoilers.
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International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal,Volume 3, Issue 1, January 2013)
238
Most of the car spoilers come made of polyurethane.
Spoilers are also made of lightweight steel while others offiberglass. These lightweight spoilers are found to be
extremely durable and do not crack, separate or sag.
Sometimes spoilers can be made of a combination of
two or three dissimilar substances. Car spoilers made of
'high impact resin' display high density with extreme
temperature resistance. They are super impact resistant.
Generally, spoilers are purchased unpainted to facilitate the
buyer paint it on an accurate color match with the car.
Mention should be made of the fact that most of the time
a car spoiler is incorrectly confused with 'wings'. While
automotive wings are devices whose intended design is to
actually generate down force as air passes around them, the
function of a car spoiler is to disrupt existing airflowpatterns.
V. COMPOSITE MATERIALS
A composite is a structural material that consists of two
or more combined constituents that are combined at a
macroscopic level and are not soluble in each other. One
constituent is called reinforcing phase and the one in which
it is embedded is called the matrix. The reinforcing phase
material may be in the form of fibers, particles, or flakes.
The matrix phase materials are generally continuous. In this
form, both fibers and matrix retain their physical and
chemical identities, yet they produce a combination of
properties that cannot be achieved with either of theconstituents acting alone. In general, fibers are the principal
load carrying members, while the surrounding matrix keeps
them, and protects them from environmental damages due
to elevated temperatures and humidity.
The composite materials have the following properties:
High specific strength
High specific stiffness
More thermal stability
More corrosion and wear resistance
High fatigue life
VI. FORMULATION OF PROBLEM AND ANALYS IS
The main aim of the present work is to investigation the
better orientation of the glass fiber in the spoiler
manufacturing. As composite material have tailoring
properties i.e., based on the users requirement material
properties of the component can be obtained by stacking
the different or similar oriented fiber together.
Design of Fiber Reinforced polymer composit
components require extensive study of material propertiebefore selecting the material to be used to make th
product. Design approach used for metallic materials could
not be utilized for polymer composite materials, since thes
materials are orthotropic in nature. Design of composit
materials is based on the classical laminate theory. Th
cumbersome mathematical solutions may be performed to
estimate the tailored material properties to be estimated by
software tools.
The design of the FRP components requires a definit
approach with consensus of discussion depending on th
functional requirements. The complex nature of failur
behavior of fiber-reinforced composites makes the desig
approach complex. In view of developing user-friendlyapproaches for design of commercial FRP products th
present work provides a pathway towards establishin
simple methods for required class of products.
Typical Aerofoil shapes have been found in a differen
NACA series from that a NACA 2412 four digit model ha
been taken for the simulation.
In the present work the Design FOIL workshop is used
to export the coordinates for geometric molding and to
estimated the lift and drag coefficients. Based on the lif
and drag coefficients the lift and drag forces are calculated
based on the below mentioned formulae:
Lift force L= *V2*S*ClDrag force D = *V2*S*Cd
To avoid the laborious processes laminate design
software is developed as a first experimental work.
The coordinates obtained form the Design FOILworkshop software are fed into CATIA sketcher and then
extruded up to one meter, this gives the foam part and then
the same coordinates are used to form the skin by giving
thickness as 3mm and then extruding up to 1m.
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International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal,Volume 3, Issue 1, January 2013)
239
Fig.4 Assembled Aerofoil Model
VII.
RESULTS
The assembled model then is imported into ANSYS.
Meshing has been done using mesh option as shown in
figure.
Fig.5 Meshed Model
The finite element modeling and analysis is used to
study the deflections and stress variation at different
locations of the spoiler and also the deflection at various
ends. The figure shows all the deflection stresses and
harmonic Analysis at different orientations of fibers.
Fig.6 Model in Workbench
Results for Aluminium material
Fig.7 Deflection For Aluminium
Fig.8 Equivalent stress For Aluminium
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International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal,Volume 3, Issue 1, January 2013)
240
Fig.9 Frequency Vs Amplitude for aluminum
Results for 00orientation
Fig.10 Deflection at 00orientation
Fig.11 Equivalent stress 00orientation
Fig.12 Frequency Vs Amplitude (00)
Results for 450orientation
Fig.13 Deflection at 45oorientation
Fig.14 Equivalent stress 450
orientation
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International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal,Volume 3, Issue 1, January 2013)
241
Fig.15 Frequency Vs Amplitude (450)
Results for 600orientation
Fig.16 Deflection at 60oorientation
Fig.17 Equivalent stress 600orientation
Fig.18 Frequency Vs Amplitude (600)
Results for 900orientation
Fig.19 Deflection at 90oorientation
Fig.20 Equivalent stress 900orientation
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International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal,Volume 3, Issue 1, January 2013)
242
Fig.21 Frequency Vs Amplitude (900)
VIII.
CONCLUSION1.
The simulation results are that [45o] orientation of
the fiber is the best orientation for the fabrication of
the spoiler.
2.
[45o] orientation of the fiber with foam gives best
result when compared the same [45o] orientation of
the fiber without foam
3.
The fabrication of the spoiler has been done with
sandwich construction..
4.The theoretical calculation and the simulation resultsdiffer i.e., due to localized buckling effect in the
sandwich construction.
IX.
SCOPE FOR FUTURE WORK
Having successfully proven that the manufacturing
concept is feasible in basic engineering terms, work i
currently in progress on Spoiler design and analysis
Although flat panel structures are relatively simple to
model for FEA, it is necessary to quantify the mechan icaproperties of the bonded joints, and to represent these in th
model efficiently.
In the current situation of limited resources, th
following aspects are recognized as being oconsiderable importance, but must wait furthefunding:
Manufacturing of different composite materials lik
Kevlar/epoxy, Boran/epoxy, Carbon/epoxy
Selection of sandwich panel component material
(skins and core) for ease and consistency o
manufacture, performance and recycling.
Optimization of adhesive for cure cycle and long term
properties.
Crashworthiness testing.
Production plant layout, process monitoring an
quality systems.
Operational considerations (e.g. thermal, acoustic and
dynamic characteristics).
Funding and in-kind support is actively being sough
from various bodies (e.g. materials suppliers
manufacturers and potential customers) to carry the projecforward.
REFERENCES
[1 ]
W.J. Cantwell et al. A comparative study of the mechanica
properties of sandwich materials for nautical construction. SAMP
Jnl., 30 (4), 45-51 (1994).
[2 ]
K. Lowe. Automotive steels. Engineering, Feb. 1995, 20-21.
[3 ] http://www.fibermaxcomposites.com/index.files/manufacturingtech
iques.htm
[4 ]
http://www.dreesecode.com
[5 ]
http://www.en.wikipedia.com
MaterialDeflection
(mm)
Von-
misses
Stress
N/mm2
Peak
frequency
(Hz)
foam 9.057 141.49 1400
Without
foam15.946 186.98 400