Aerodynamic drag is one of the main obstacles to decreases the speed of the vehicle and also increases the fuel consumption of the vehicle. Extensive research is undergoing for development of aerodynamically optimized vehicle designs. The main objective of the project is to increase the fuel efficiency by designing car with different type of aerodynamic attachments like diffuser, spoiler, front and rear wing etc., to reduce drag coefficient. The car body is modeled using solidworks and analysis is done using Ansys Workbench and Drag coefficient is determined to show decrease in Drag force and increase in fuel Efficiency. It is observed that Cd for the modified car is lower, compared to the standard car. Cd for the car with front splitter and rear spoiler of angle 19 is found to 0.183 and car with diffuser and vortex generator have drag of 0.211, whereas standard race car have Cd of 0.318. But increases in spoiler angle cd value increases from certain angle.

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GMR Institute of Technology
An Autonomous Institute Affiliated to JNTUK,Kakinada
Dept. of Mechanical engineering
Main Project –Review 3

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Under the Guidance:
Dr.Ch. Vinod Babu
Asst.professor
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Design and Analysis of Car Body to Reduce
Drag and Increases Fuel Efficiency
Presented by:
Student Name
T. Naveen Deepak
E. Sai Krishna
Roll No
(18345A0307)
(17341A0329)
K. Tarun Satya Venkatesh (17341A0344)
D. Babluraj
G.U.N. Venkateswarulu
(18345A0304)
(17341A0332)

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 Aerodynamic drag is one of the main obstacles to decreases the speed of the
vehicle and also increases the fuel consumption of the vehicle. Extensive research
is undergoing for development of aerodynamically optimized vehicle designs.
 The main objective of the project is to increase the fuel efficiency by designing
car with different type of aerodynamic attachments like diffuser, spoiler, front and
rear wing etc., to reduce drag coefficient.
 The car body is modeled using solidworks and analysis is done using Ansys
Workbench and Drag coefficient is determined to show decrease in Drag force and
increase in fuel Efficiency.
 It is observed that Cd for the modified car is lower, compared to the standard car.
Cd for the car with front splitter and rear spoiler of angle 19 is found to 0.183 and
car with diffuser and vortex generator have drag of 0.211, whereas standard race
car have Cd of 0.318. But increases in spoiler angle cd value increases from
certain angle.
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ABSTRACT

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Introduction
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 Aerodynamics is the study of how moving objects interact with theair.
 Design engineers are adapting the concepts of aerodynamics to enhance
the efficiency of the vehicle. Fuel consumption due to aerodynamic drag
consumes about half the vehicle's energy.
 Thus, reducing the drag is one of the major approaches automotive
manufacturers opt for. Shaping the body of the vehicle and inclusion of
various add on devices contributes to optimization for low drag, which
becomes an essential part of the design process.
 Drag Force predominantly depends upon the velocity, frontal area, and
coefficient of drag of the body.
 By adding aerodynamic attachment like spoiler ,vortex generator etc to
the car body which could reduce the drag of the vehicle by 25% which
further improves the fuel efficiency of the vehicle.

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 A Rear diffuser, in an automotive term, is a shaped section of the car
under body which improves the car's aerodynamic properties.
 A vortex generator (VG) is an aerodynamic device, consisting of a small vane
attached to a lifting surface or a rotor blade of a wind turbine. Vortex
Generators may also be attached to some part of an aerodynamic vehicle
such as an aircraft fuselage or a car.
 A spoiler is an automotive aerodynamic device whose intended design
function is to 'spoil' unfavorable air movement across a body of a vehicle in
motion, usually described as turbulence or drag. Rear spoilers are provided to
increase the negative lift of the vehicle.
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a.Diffuser
c.Spoiler
b.Vortex Generator

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Literature Survey
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s.no Author
Name
Journal Name Title of paper Major Findings
1 Ravi
Kumar B
et al.
Australian
Journal of
Mechanical
Engineering
Aerodynamic design
optimization of an
automobile car using
computational fluid
dynamics approach
•Modified Car by altering the
rear slot angle ranging from 0° to
13°.
•The analysis is carried out using
ANSYS.
•The drag has been reduced from
0.3454 to 0.2322.
• The 12° duct angle was found to
be the optimum duct angle
2 K.Balaman
ikanda
Suthan1 et
al.
International
Research Journal
of Automotive
Technology
CFD Analysis and
Drag Reduction in
Maruti Suzuki Swift
•Modified the Swift by adding
both Diffuser and Vortex
generator.
•The Cd value is reduced from
0.408 to 0.342

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S no. Author
Name
Journal
Name
Title of paper Major Findings
3 Sneh
Hetawala et
al.
Procedia
Engineering
Aerodynamic
Study of Formula
SAE Car
•Compared three Models
•Model 1 standard SAE
•Model 2 with cutout firewall
•Model 3 with both cutout
firewall and front wing
•The model 3 has given less cd
value and better fuel efficiency.
4 Kelbessa
KeNea
Deressa1 et
al.
International
Research
Journal of
Engineering
Design And
Analysis Of A
New Rear Spoiler
For Su Vehicle
Mahindra Bolero
Using CFD
•The modelled vehicle of Bolero
was analyzed in CFD with
different spoiler angles.
•It is observed that Cd value is
increasing with more elevation in
base curve when it is analyzed.
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S
no
Author
Name
Journal
Name
Title of Paper Major Findings
5 Mohammad
Arief
Dharmawan
et al.
AIP
Conference
Proceeding
Aerodynamic
Analysis of
Formula Student
Car
• For the vehicle without wings, it
has average drag coefficient 0.728
•While vehicle with aerodynamic
device attachment has average
drag coefficient 0.56.
•Using aerodynamic accessory
decreased drag coefficient about
23%
6 Rubel
Chandra Das
et al.
Procedia
Engineering
CFD Analysis of
Passenger
Vehicleat Various
Angle of Rear End
Spoiler
•Six modifications are simulated
& 12 degree spoiler inclination
angle model is the most optimum.
•Rear spoilers redirect the airflow
behind the vehicle & increase the
negative lift of the vehicle
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S
no
Author
Name
Journal
Name
Title of Paper Major Findings
7 S.M. Rakibul
Hassan
et al.
Procedia
Engineering
Numerical Study
on Aerodynamic
Drag Reduction
of Racing Cars
•Compared standard model with rear
underbody modification and rear
under body diffuser.
•Aerodynamic drag reduction by rear
under body modification results in up
to 22.13%
• Rear under-body diffuser results
9.5% reduction of drag coefficient.
8 M. H. Tonpe
et al.
International
Journal of
Engineering
Research &
Technology
Aerodynamic Drag
Force Analysis for
Light Commercial
Vehicle
•Compared three models
1. Base model
2. Upper rear end cut
3. Upper rear end tale plate
• It is seen that the modified model
with the upper rear tale plate
attachment reduces the drag at
some extent

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No
Author
Name
Journal
Name
Title of Paper Major Findings
9 Mohamme
d Amer
et al.
Journal of Mining
and Mechanical
Engineering
Experimental
Investigation
of a Spoiler’s
Impact on the
Flow Pattern
of a High-
Speed Sport
Car
•Compared BMW car with
different spoiler angles
•By using water tunnel test and
wind tunnel test
•12° is the optimal angle of
attack for the spoiler with low
Cd value.
10 Michal
Remer et al.
International
Journal of
Mechanical
Sciences
The influence of
different
aerodynamic
setups on
enhancing a
sports car’s
braking
•Compared four model
1. Base mode
2. Wing 48˚
3. Wing 48˚ Spoiler 0˚
4. Wing 48˚ Spoiler 55˚
• Base model has given low
Cd value.

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S
No
Auth
or
Nam
e
Journal
Name
Title of Paper Major Findings
11 Muhamm
ad Zaid
Nawam et
al.
Journal of
Advanced
Research in Fluid
Mechanics and
Thermal Sciences
Simulation
Study on the
Effect of Rear-
Wing Spoiler on
the Open
Aerodynamic
Performance of
Sedan Vehicle
•They have analyzed four
different type of rear wing of
different shapes on sedan car.
•The base model has given less
cd value of 0.192
12 Xingjun HU
et al.
International
Conference on
Physics Science
and
Technology
Influence of
Different Diffuser
Angle on Sedan’s
Aerodynamic
Characteristics
•They have taken a sedan car
with different diffuser angles
and analyzed the cd
•6 degrees angle has given the
low cd value of 0.24

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S
No
Author
Name
Journal
Name
Title of Paper Major Findings
13 Jonathan
Lane et al.
SAE Int. Journal Racecar Front
Wing
Aerodynamics
•The behavior of a wing with
small ground clearance is
studied using a CFD method to
simulation a racecar front wing.
14 Shinji
Kajiwara
Automotive
Engine
Technology
Passive variable
rear-wing
aerodynamics of
an open-wheel
racing car
• The passive-type rear wing
generates a downforce
equivalent to a fixed-type rear
wing at low speed, and
reduces downforce at high
speed. That is, it makes it
possible to reduce drag.

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Methodology
 Modelling of car is done using Catia and
different modification are done to absorb
Drag coefficient of a model.
 Then the model file is imported to the
Ansys Workbench software for analysis
purpose.
 The next step is meshing of the enclosure and
the vehicle. Car model along with the flow
domain is meshed.
 Boundary conditions are practically
essential for defining a problem and also
used to determine approximate results.
 Finding coefficient of drag and compare with
standard model without aerodynamic
attachments.
Drafting
Modelling
Boundary
conditions
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Drag Force
analysis by Ansys
Workbench

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MODEL DISCRIPTION
S.No Model
1 Base model of the car without aerodynamic attachments
2
Base model with front splitter and rear end spoiler of 17˚
Base model with front splitter and rear end spoiler of 19˚
Base model with front splitter and rear end spoiler of 21˚
3 Base model with rear end diffuser and vortex generator

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Modeling and Analysis Procedure
 Initial step of creating the 3D model of car is to setup the layout in Catia V5 .
 These layouts were arranged in the different planes as top view, front view, right views.
 In these view planes the 2D sketch has been drawn and using the 3D tools like extrude,
cut-extrude, etc., the car model has to be created.
 Now the next step is to save the file in .step or .igs formats.
 Export of cad file to Ansys for analysis purpose.
 Boundary conditions are essential component of a mathematical model. They direct the
motion of flow which leads to unique solution.
 The coefficient of drag is determined using Ansys.

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Front view
Top view
Right side view

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Fig 3 3D cad model of car

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Results and discussion
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Model 1 : 3D Model Of Standard model car
Standard model of car body has designed in CATIA V5 and analyzed using
ANSYS software.
The coefficient of Drag obtained for the standard car using Ansys software is 0.318
The air velocity is taken as 36.11m/s
The area is taken as 6.4m^2.
The drag force obtained from analysis is 1628.55N.
The density of fluid is taken as 1.224kg/m^3.

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Fig 4 standard model of car body

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Fig 5 Pressure distribution

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Fig 6 velocity flow & separation view

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Model 2 : 3D Model Of Car With Front Splitter And Rear Spoiler
Standard model of car body with front splitter and Rear spoiler has designed
in CATIA V5 and analyzed using ANSYS software.
The spoiler angles are taken at 17˚,19 ˚,21 ˚.
The obtained coefficient of Drag for model 2 with three different spoiler angles
17 ˚, 19 ˚ and 21 ˚ using Ansys software is 0.213,0.183 and 0.661.
The air velocity is taken as 36.11m/s
The area is taken as 6.8m^2.
The drag force obtained from analysis is 1159.272N.
The density of fluid is taken as 1.224kg/m^3.

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Fig 7: 3D model of car with front splitter
Fig 8: 3D model of car with rear spoiler

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Fig 9 : path line velocity flow magnitude view Fig 10 : velocity contour flow magnitude view

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Model 3: 3D Model Of Car With Rear end Diffuser And Vortex Generator
 Standard model of car body with Rear diffuser and Vortex generator has
designed in CATIA V5 and analyzed using ANSYS software.
 The Ogive type vortex generator is taken.
 Cd value obtained from ansys - 0.211
 The air velocity is taken as 36.11m/s
 The area is taken as 18.6m^2.
 The density of fluid is taken as 1.224kg/m^3.
 The drag force obtained is 3139.258 N

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Fig 11: 3D model of car with vertex generators & rear end diffuser

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Fig 12 velocity contour of model 3 Fig 13 velocity streamline of model 3

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Table 2 coefficient of drag of different models
S.no Model Coefficient of drag
1 Base model of the car without aerodynamic attachments 0.318
2 Base model with front splitter and rear end spoiler of 17˚ 0.213
3 Base model with front splitter and rear end spoiler of 19˚ 0.183
4 Base model with front splitter and rear end spoiler of 21˚ 0.661
5 Base model with rear end diffuser and vortex generator 0.211

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S.No Parameter Boundary condition Values
1 Velocity Inlet •Magnitude measured normal
to boundary condition
•Turbulence intensity
36m/s
1%
2 Fluid properties •Fluid type
•Density
•Kinematic viscosity
Air
1.224kg/m^3.
1.78×10^-5
kg/(m-s)

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Conclusion
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• In the project, we have carried out a comprehensive analysis over the car
body by adding the different aerodynamic attachments like spoiler, diffuser,
vertex generators, front splitter.
• The analysis is carried out using ANSYS Fluent, The results were promising,
by showing considerable decrease in drag coefficient by the adopted
modifications.
• Standard Car with front splitter and rear spoiler angle at 19˚ Drag co-efficient
is found to get reduced from 0.318 to 0.183.
• Standard car with Rear diffuser and vortex generator drag coefficient is found
to get reduced from 0.318 to 0.211.

32. • These design modifications can be implemented which will lead to a
considerable decrease in fuel consumption and increase in fuel economy.

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