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)
Analysis of NACA 2412 for Automobile Rear Spoiler Using
Composite Material
A. Sunanda1, M. Siva Nayak2
1
Asst. prof, Department of Mechanical Engg., SNIST, Ghatkesar, Hyderabad.
Asst Prof, Mechanical Engineering Department, Rise Groups Of Institution, Ongole.
2
However this car was banned as the cornering speeds
reached, up to 1.7g, were thought too dangerous. This was
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 far
automotive 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 a
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 piece
of metal about one-half to two inches high to the rear
decklid. This trapped air on the decklid and created down
force to stabilize the car. It did not make the Dodge a
standout car, but other manufacturers did see the
aerodynamic perk of adding something to the back of the
car to increase down force.
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
II.
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 1970’s, once again by ChevroletChaparral.
B ASIC FUNCTION O F SPOILER
The main function of a spoiler is diffusing the airflow
passing over and around a moving vehicle as it passes over
the vehicle. This diffusion is accomplished by increasing
amounts of turbulence flowing over the shape, “spoiling
“the laminar flow and providing a cushion for the laminar
boundary layer often spoilers are added solely for
appearance with no thought towards practical purpose.
An important principle in aerodynamics is Daniel
Bernoulli's principle. It is this principle that says that where
there is an increase in flow velocity of a gas there is a
decrease in pressure for a fixed volume. This is due to
Newton, as he said that energy cannot be created or
destroyed. This theory is used extensively in aeronautical
applications. The shape of an aircraft wing causes the air to
flow faster over the top surface than the bottom one.
Bernoulli’s principle says that this means there is a lower
pressure on the top surface compared to the bottom surface
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)
However if the wing were turned upside down then the
resultant force would be downwards, this is called down
force 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.3 Forces created by airflow over a car body
III.
B ENEFITS O F C AR SPOILERS
A spoiler is a flattish, slightly curved appendage on the
rear of the vehicle. Spoilers are found on racing cars and
high performance sports cars. They primarily reduce the
amounts of lift and drag a vehicle experiences and at higher
speed the force of the wind pushes down on the spoiler
adding additional traction for the tires. While most stock
spoilers usually add no discernable performance, a racing
spoiler that is usually larger in size and more aerodynamic
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 fuelefficient. This mechanical accessory can make the car
stable on roads. Spoiler improves vehicle stability by
decreasing lift or decreasing drag that may cause
unpredictable handling in a car speed. Spoiler disrupts the
airflow going over a moving car thereby reducing the
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 and
providing a cushion for the laminar boundary layer.
Most of the time, the car spoiler is a styled piece of
fiberglass, which enhances the aerodynamics of the car.
Due to increase in traction a car in motion brakes, turns and
accelerates with more stability. Drag increases as the speed
of the car increases. It can be seen that some spoilers are
effective at very low speeds often generating excessive
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 the
transition in shape between the roof and the rear and the
trunk and the rear. This minimizes the turbulence at the rear
of the vehicle. Some rear spoilers come with a warning
brake light built into the spoiler.
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 created
here. 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.
IV.
C AR SPOILER T YPES
Spoiler wings come in various shapes and sizes and in
numerous designs. They could be high hopped, Supra
styled, Lip spoiler or wings wrest spoilers.
237
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)
Most of the car spoilers come made of polyurethane.
Spoilers are also made of lightweight steel while others of
fiberglass. 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 airflow
patterns.
V.
Design of Fiber Reinforced polymer composite
components require extensive study of material properties
before selecting the material to be used to make the
product. Design approach used for metallic materials could
not be utilized for polymer composite materials, since these
materials are orthotropic in nature. Design of composite
materials is based on the classical laminate theory. The
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 definite
approach with consensus of discussion depending on the
functional requirements. The complex nature of failure
behavior of fiber-reinforced composites makes the design
approach complex. In view of developing user-friendly
approaches for design of commercial FRP products the
present work provides a pathway towards establishing
simple methods for required class of products.
Typical Aerofoil shapes have been found in a different
NACA series from that a NACA 2412 four digit model has
been taken for the simulation.
COMPOSITE M ATERIALS
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 the
constituents 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:





VI.
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 lift
and drag coefficients the lift and drag forces are calculated
based on the below mentioned formulae:
Lift force L= ½ ρ*V2*S*Cl
Drag force D = ½ ρ*V2*S*Cd
To avoid the laborious processes laminate design
software is developed as a first experimental work.
The coordinates obtained form the Design FOIL
workshop 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.
High specific strength
High specific stiffness
More thermal stability
More corrosion and wear resistance
High fatigue life
FORMULATION O F P ROBLEM AND ANALYSIS
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.
238
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)
Fig.4 Assembled Aerofoil Model
VII.
Fig.6 Model in Workbench
RESULTS
Results for Aluminium material
The assembled model then is imported into ANSYS.
Meshing has been done using mesh option as shown in
figure.
Fig.7 Deflection For Aluminium
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.8 Equivalent stress For Aluminium
239
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)
Fig.12 Frequency Vs Amplitude (00)
Results for 450 orientation
Fig.9 Frequency Vs Amplitude for aluminum
0
Results for 0 orientation
Fig.13 Deflection at 45o orientation
Fig.10 Deflection at 00 orientation
Fig.14 Equivalent stress 450 orientation
Fig.11 Equivalent stress 00 orientation
240
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)
Fig.15 Frequency Vs Amplitude (450)
Results for 600 orientation
Fig.18 Frequency Vs Amplitude (600)
Results for 900 orientation
Fig.16 Deflection at 60o orientation
Fig.19 Deflection at 90o orientation
Fig.17 Equivalent stress 600 orientation
Fig.20 Equivalent stress 900 orientation
241
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)
IX.
SCOPE FOR FUTURE W ORK
Having successfully proven that the manufacturing
concept is feasible in basic engineering terms, work is
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 mechanical
properties of the bonded joints, and to represent these in the
model efficiently.
In the current situation of limited resources, the
following aspects are recognized as being of
considerable importance, but must wait further
funding:
• Manufacturing of different composite materials like
Kevlar/epoxy, Boran/epoxy, Carbon/epoxy
• Selection of sandwich panel component materials
(skins and core) for ease and
consistency of
manufacture, performance and recycling.
• Optimization of adhesive for cure cycle and long term
properties.
• Crashworthiness testing.
• Production plant layout, process monitoring and
quality systems.
• Operational considerations (e.g. thermal, acoustic and
dynamic characteristics).
Funding and in-kind support is actively being sought
from various bodies (e.g. materials suppliers,
manufacturers and potential customers) to carry the project
forward.
Fig.21 Frequency Vs Amplitude (900)
Material
Deflection
(mm)
Vonmisses
Stress
N/mm2
Peak
frequency
(Hz)
foam
9.057
141.49
1400
Without
foam
15.946
186.98
400
VIII.
CONCLUSION
1. 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 results
differ i.e., due to localized buckling effect in the
sandwich construction.
REFERENCES
[1 ] W.J. Cantwell et al. A comparative study of the mechanical
properties of sandwich materials for nautical construction. SAMPE
Jnl., 30 (4), 45-51 (1994).
[2 ] K. Lowe. Automotive steels. Engineering, Feb. 1995, 20-21.
[3 ] http://www.fibermaxcomposites.com/index.files/manufacturingtechn
iques.htm
[4 ] http://www.dreesecode.com
[5 ] http://www.en.wikipedia.com
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