This document provides an overview of a project report on the aerodynamics analysis of automobiles. The report was submitted by G. Srikar in partial fulfillment of the requirements for a Bachelor of Technology degree. The report includes declarations, certificates of approval, acknowledgments, and outlines the objectives, scope, and methodology of analyzing the effects of adding aerodynamic components like diffusers, vortex generators, spoilers, tire covers, and air ducts on a vehicle model using computational fluid dynamics software. The goals are to estimate the percent reductions in drag coefficient and lift coefficient, and to improve vehicle fuel efficiency, acceleration, and handling.

1. AERODYNAMICS ANALYSIS OF AUTOMOBILES
A Project Report
Submitted in partial fulfilment of the Requirements for the award of the
Degree of Bachelor of Technology
IN
Department of Mechanical Engineering
By
G. SRIKAR 150070108
Under the Supervision of
D. Phanindra Kshatra
Assistant Professor
Dept. of Mechanical Engineering
KONERU LAKSHMAIAH EDUCATION FOUNDATION
Green Fields, Vaddeswaram- 522502,
Guntur (Dist.), Andhra Pradesh,
April - 2019

2. KONERU LAKSHMAIAH EDUCATION FOUNDATION
DEPARTMENT OF MECHANICAL ENGINEERING
Declaration
The Project Report entitled “Studies on Mechanical Properties of Aerodynamics
analysis of automobiles is a record of bonified work of SRIKAR (150070108)
submitted in partial fulfilment for the award ofBachelor of Technology in Minor
Project during the academic year 2018-19.
I also declare that this report is of my own effort and it has not been submitted
to any other university for the award of any degree.

3. KONERU LAKSHMAIAH EDUCATION FOUNDATION
DEPARTMENT OF MECHANICAL ENGINEERING
CERTIFICATE
This is to certify that the Project Report entitled “Study on Mechanical
Properties of in SRIKAR (150070108)partial fulfilment for the award of
Bachelor of Technology in Project during the academic year 2018-19.
Signature of the Supervisor Signature of the HOD
Mr. PHANINDRA KSHATRA DR. A. SRINATH
Signature of the EXTERNAL EXAMINER

4. ACKNOWLEDGMENT
It is great pleasure for us to express our gratitude our honourable president Sri.
Koneru Satyanarayana, for giving the opportunity and platform with
facilities in accomplishing this Project.
We express the sincere gratitude to our principal Dr. K. Subba Rao for his
administration towards our academic growth.
We express sincere gratitude to our head of department Dr. A. Srinath for his
leadership and constant motivation provided in successfulcompletion of our
academic semester.
We express my sincere thanks to our project head Dr. G. Murali for his novel
association of ideas, encouragement, appreciation and intellectual zeal
which motivated us to venture this Project successfully.
We express my sincere thanks to our project supervisor Mr. PHANIDRA
KSHATRA for his novel support and encouraged us throughout our course
and explained the problem-solving techniques to real-time problems and leads
to complete our coursesuccessfully.
Finally, it is pleased to acknowledge the indebtedness to all those who devoted
themselves directly to take this project success.

5. Contents
Sl. No. Content Page No.
1 Abstract 6
2 Introduction 7
3 Review of Race Car Aerodynamics 8
3.1 Review of desired BodyKit Specifications 10, 11
4 Preliminary Design Study 12
4.1 Drag 13
4.2 Bodywork Streamlining 14, 15
4.3 Preliminary Design Study Summary 16
4.4 Initial Design 17
5 CFD 18
5.1 Expected Flow Features 19
5.2 Model Preparation 20
5.3 Governing Equations 21
5.4 Boundary Conditions 22
5.5 Wall Conditions 22
5.6 Computational Methods 23
6 Discussion 24
7 Conclusion 25
8 References 26

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1. ABSTRACT:
Aerodynamics is the most importance factor when it comes to resistive
force acting on the vehicle. It comes into the picture when a vehicle is
moving in a fluid medium, there are numerous factors such as lift side
force, and which are responsible for this resistance aerodynamics drag
will not only open the doors for higher top speed of the will also reduce
the overall fuel consumption of the vehicle and increase and
comfortability. These above factors are using the passenger cars. These
factors are also determined cars marketing strategies for a passengers’
cars.
In aerodynamics vehicle motion drag force are while opposing the
coefficient of the drag to responsible for increasing the friction coefficient
of the drag will decrease the force of the solid works to designing the aero
foils of the spoilers to design the solid works.

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2.INTRODUCTION:
In modern days, cars should performance, handle, have good safety, and comfort of a car are
affected by its aerodynamic. Getting high power directly from the engine is just not enough to
judge the performance of the car. Aerodynamics affects the performance of vehicle due to
change in parameters such as lift and drag forces which play a significant role at high speed.
With improvement in computer technology, manufacturers are looking toward CFD instead of
wind tunnel testing to reduce the testing time and keep the cost of low. In this project by
reducing the difference in pressure the drag force will be reduced hence the fuel consumption
will be reduced. The car body is often optimized for reducing the drag resistance but in this
project someof the additional components are added to reduce the drag and lift. The additional
components are diffuser, vortex generator, spoiler, tyre cover and air ducts. Thereby reducing
the drag and lift will improve the car handling behavior, acceleration and fuel efficiency. The
approachneeded to justify the amount of drag and lift that can be reduced by addition of those
components as compared to the car model without those additional components.

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3.Review ofRace CarAerodynamics
AERODYNAMICS:
Aerodynamics, from is the studyofmotion of air, particularly as interaction with a solid object,
suchas an airplane wing. It is a sub-field of fluid dynamics and gas dynamics and many aspects
of aerodynamics theory are common to these fields. The term aerodynamics is often used
synonymously with gas dynamics, the difference being that "gas dynamics" applies to the study
of the motion of all gases, is not limited to air. The formal study of aerodynamics began in the
modern sense in the eighteenth century, although observations of fundamental concepts
such as aerodynamics drag were recorded much earlier. Most of the early efforts in
aerodynamics were directed toward achieving which was first demonstrated. Since then, the
use of aerodynamics through mathematical analysis, empirical approximations, wind
tunnel experimentation, and computer software has formed a rational basis for the
development of heavier-than-air flight and several other technologies. Recent work in
aerodynamics has focused on issues related to compressible flow, turbulence, and boundary
layers and has become increasingly computational in nature.
Classification of aerodynamics based on flow environment: External Aerodynamics.
Field of Applications:
1.AerospaceEngineering.
2.Design of Automobile.
3.Prediction of forces.
4.In design of bridges and buildings for calculating wind loads.
Aerodynamic Forces on Aerofoil:

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Consider an aerofoil move through air, forces which are considered for aerodynamics analysis
over aerofoil are:
1.Lift (cause bodyto rise).
2.Drag (Fluid resistance).
3.Weight.
1. Lift: Lift is the force that directly opposes the weight of an airplane and holds the airplane
in the air generated by every part of the airplane, but most of the lift on a normal airliner is
generated by the wings. Lift is a mechanical aerodynamic force produced bythe motion of the
airplane through the air.
2.Drag: A simpler explanation drag is the aerodynamic force that opposes an aircraft's motion
through the air. Drag is generated by the difference in velocity between the solid object and
the fluid.
3. Weight: The weight of an object is defined as the force gravity on the object and may be
calculated as the mass times the acceleration of gravity, w = mg. Since the weight is a force,
its SI unit is the newton.
Automotive Aerodynamics: Automotive Aerodynamic is the studyofthe aerodynamics of road
vehicles. It mains goals are reducing drag, wind and noise, minimizing noise emission, and
preventing undesired lift forces and other causes of aerodynamics instability at high speeds.
Air is also considered a fluid in this case. Aerodynamics drag is the force opposite to the
direction of motion that acts on a bodymoving through air. Car is the high speed vehicle and
when it runs on the road it faces huge amount ofdrag forceoppositeto its moving direction.The
conceptof car model which will it very small drag force and also to reduce the corresponding
drag coefficient the shapes of the car is necessary to its desires the outcome.Both the
computational and experimental approaches are applied to identify the areas todesign the car
model.
STUDY OF AERODYNAMICS IN CARS:
Automotive aerodynamics is the study of the aerodynamics ofroad vehicles. Its main goals are
reducing drag and wind noise, minimizing noise emission, and preventing undesired lift forces

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and other causes of aerodynamic instability at high speeds. Air is also considered a fluid in this
case. There are 2 types:
1.Drag force.
Lift or Down force.
1.Drag Force: Fluid dynamics, drag, forceacting opposite to the relative motion of any object
moving with respect to a surrounding fluid. some energy is lost to move the car through the
air and this energy is used to overcome a Drag force.
In vehicle aerodynamics drag is due to frontal pressure and Rear vacuum.
For calculating drag force following formula is use
F=1/2 CDAV^2.
Where, F= Aerodynamic drag force.
C= Coefficient of drag.
D= Density of air.
A= Frontal area.
V= Velocity of object.
Drag coefficient: In fluid dynamic the drag coefficient is a dimensions quantity that is used to
quantity the drag or resistance of an objectin fluid environment, such as air orwater. It is used
in the drag equation in which a lower drag coefficient indicates resistance of an object in a
fluid environment or hydrodynamic drag.
FRONT END OF CAR:
*Drag force due to Frontal Pressure: This drag force is caused by the air attempting to flow
around the front of the car. When air molecules approach the front of the car they begin to
compress and raise of the air pressure front of car.
*Frontal pressureis reduced by minimizing exposed frontal surface area and making front end
smooth, continuous curve originating from the line offront bumper allowing the air molecules
to pass smoothly.

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REAR END OF CAR:
Rear vacuum is caused by the flow Detachment in the air flow as the car passes through it.
Flow Detachment is inability of air molecules to fill the empty zones which are created at the
rear end of vehicle.
roof and trunk which increases the chances of rise of vehicle.
2.LIFT OR DOWN FORCE:
Every object travelling through air creates either a lifting or down force situation. Down force
is the same as the lift experienced by airplane wings, only the difference is, it acts to press
down, instead of lifting up
It is calculated as
F=(1/2) CLDV^2 A
*For a given volume of air, the higher the speed of air molecules, the lower is the pressureand
vice-versa.

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*This creates low pressure over hood.
*The underside of the car is also responsible for creating lift or down force.
If a car’s front end is lower than the rear end, then the widening gap between the underside and
the road generates vacuum or low-pressure area, and therefore suction is created that equates
to down force.
Overall to increase the performance of car aerodynamically:
It is necessary to Generate right amount of Down force while keeping Drag force to a
minimum level.
AERODYNAMICS DEVICES IN CARS WE ARE USED IN:
SPOILERS:
They act like barriers to air flow, in order to build up higher, air pressure in front of the truck
of car.

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It is mostly used in race cars which are lighter in rear end because low pressure created above
the trunk which lifts the rear end of car.
Hence spoilers are used to create high pressure that pushes down the car and also it gives
stability at corners.
AERODYNAMICS DEVICES IN AUTOMOBILES ARE USED:
1.DIFFUSERS.
2.AIR VENTS.
3.VORTEX GENERATORS.
4.WHEEL CAPS
5.SPOILER OR WINGS
1.DIFFUSERS:
These are present at the bottom of the vehicles to decreases the pressure and increases the
velocity of the moving air.

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2.AIR VENTS: These are a type of openings into the car the aim of these vents is to divert the
flow of air.
VORTEX GENERATORS:
These are some type ofsmall devices that are placed on top surface ofthe vehicle that are useto
create vortexes which makes the air to spin and make to stick to the boundary of the surface.

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WHEEL CAPS: These are caps that are placed above the wheel surface such that they divert
the flow of air into wheel by creating unnecessary drag.
SPOILERS AND WINGS:
A spoiler is an automotive aerodynamic device whose intended design function is to ‘spoil’ air
movement across a body of a vehicle in motion. Spoilers on the front of a vehicle are often
called air dams, because in addition to directing air flow they also reduce the amount of air
flowing underneath the vehicle which reduces aerodynamic lift. Spoilers are often fitted to race
and high-performance sports cars, although they have become common on passenger vehicles
as well. Some spoilers are added to cars primarily for styling purposes and have either little
aerodynamic benefit or even make the aerodynamics worse. The main design goal of a spoiler
in passenger vehicles is to reduce drag and increase fuel efficiency.

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METHODS FOR EVALUATING AERODYNAMICS OF CARS:
1.Wind Tunnel:
A wind tunnel is a tool used in aerodynamic research to study the effects of air moving past
solid objects. The test object, often called a wind tunnel model, is instrumented with suitable
sensors to measure aerodynamic forces, pressure distribution, other aerodynamic related
characteristics.

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2.SOFTWARES:
There are many software’s in this world where we can perform aerodynamics analysis on car.
Number of software’s are developed for the analysis and optimization of aerodynamics in
automobiles.
For the design and analysing aerodynamics the most commonly used software’s are CATIA,
HYPERMESH, ICEMCFD, FLUENT and other CFD software. Software programs makes
possible to test small size parts which are costly in the wind tunnel
3D experience software:
3DXL software or 3D experience software the New Nintendo 3DS is a c developed by Nintendo. It is the
fourth system in the Nintendo 3DS family of handheld consoles, following the original Nintendo 3DS,
the Nintendo 3DS XL, and the Nintendo 2DS. The system was released in Japan on October 11, 2014, in
Australia and New Zealand on November 21, 2014, on January 6, 2015 in Europe in a special Club Nintendo-
exclusive "Ambassador Edition", and at retail in Europe on February 13, 2015. Like the original 3DS, the New
Nintendo 3DS also has a larger variant, the New Nintendo 3DS XL, released in all three regions. In North
America, the New Nintendo 3DS XL was while the standard-sized New Nintendo 3DS was released later
SolidWorks currently markets several versions of the SolidWorks CAD software in addition
to drawings, a collaboration tool, and DraftSight, a 2D CAD product.
SolidWorks was headed by John McAloney from 2001 to July 2007 and Jeff Ray from 2007
to January 2011. The current CEO is Gian Paolo Basis from Jan 2015. Gian Paolo Basis

18. 18
replaces Bertrand Scot, who is promoted Vice President Sales of Dassault Systems’ Value
Solutions sales channel.
Ansys software. (Analysis of car aerodynamics)
Ansys Inc. is an American public company based in. It develops and markets engineering
simulation software. Ansys software is used to design products and semiconductors, as well as
to create simulations that testa product's durability, temperature distribution, fluid movements,
and electromagnetic properties.
Ansys was founded in 1970 by Swansonsold his interest in the companyto venture capitalists
in 1993. Ansys went public on in 1996. In the 2000s, Ansys made numerous acquisitions of
other engineering design companies, acquiring additional technology for fluid dynamics,
electronics design, and other physics analysis.
Ansys software is used to design products and semiconductors, as well as to create simulations
that test a product'sdurability, temperature distribution, fluid movements, and electromagnetic
properties. Ansys was founded in 1970 by John Swanson.

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METHOLODY
Objectives
1) To analyse the effect of diffuser, vortex generator, spoiler, tyre cover and air ducts with
diffuser on vehicle in term of velocity and pressure.
2) To estimate percent reduction and compare the drag coefficient and Lift coefficient of
vehicle between with and without diffuser, vortex generator, spoiler, tyre coverand air ducts with
diffuser.
3) To improve the fuel efficiency, acceleration and handling behaviour of the car.
Scopes
1) Study on aerodynamics drag reduction by diffuser, vortex generator, spoiler, tyre cover
and air ducts with diffuser.
2) Redevelop the existing modelof diffuser, vortex generator, spoiler, tyre coverand air ducts
with Solid Work 2016.
3) Simulate the model by using Computational Fluid Dynamic (CFD) in Solid Works Flow
Simulation 2016.
4) To compare the drag and lift for both with and without diffuser, vortex generator, spoiler,
tyre cover and air ducts with diffuser

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Modelling
Modelling, the geometries of the reference and non-tested store configurations are created. The
geometric modelling is performed in the surface modelling software Solid Works 2016. The basic
building objects of the sumo models are bodies and wings. Each model may consist of an
arbitrary number of suchobjects. The user also has the option to define parts of objects as inflow
and outflow regions. Bodies are defined by specifying points at the body surface at a series of
cross-sections. The software connects the cross-sections using interpolation, thereby creating a
continuous bodysurface.
Mesh Generation:
The surface mesh for the finished, integrated model is obtained using the built-in meshing
Features of Solid Works 2016. The unstructured mesh is generated automatically, based on the
geometries of the supplied model and a number ofuser-defined parameters. Of these parameters,
which can be set separately for each surface – body, inflow/outflow region or control surface –
in the model, the most prominent are the definitions of maximum and minimum element edge
length. These allow the user to choose which surfaces should be resolved in greater detail and
which should be resolved in less detail.

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CFD (COMPUTATIONAL FLUID DYNAMICS)
. CFD means computational fluid dynamic is branch of fluid mechanics that uses numerical
analysis and data structures to solve and analyse problems that involve fluid flows.
. CFD has also become one of the basic methods of approach that can be employed to solve
the problems fluid dynamics and heat transfer.
DRAG COEFFICIENT:
. The formula for calculating drag coefficient is
WHERE
A=area of the surface(m)
P=density of air(kg/m^3)
Cd=dragcoefficient
V=velocity of air(m/s)
FD=forceacting on the body(N)
 measuring vibration frequency and amplitude of surfaces.
Effectof aerodynamics during acceleration:
During acceleration, the most important, decisive factors are the tires, good aerodynamics and
the engine power. The driving forceon the wheels, which depends onthe load on tires including
aerodynamic downforce, and tire adhesion, must balance the inertia forces and aerodynamic
drag forces. During the acceleration of a car, there are two limitations. The first one is the
restriction on the power transmitted by the tires at the contact with the road. The second is the
power generated by the engine. At low speed, the traction is braking phase could be achieved
by cars with the greatest value of aerodynamic downforce and a high value of aerodynamic
drag.
During braking and the resulting reduction of car velocity, the aerodynamic forces rapidly
decrease. For a car with a high aerodynamic downforce improving operation of mechanical
brakes and cars using aerodynamic braking stopping force during braking decreases rapidly,
but the car stops quickly. Such a car has the shortest braking distances.

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Effectof aerodynamics during braking:
The maximum braking forcetransmitted by the tire depends onthe downforceand the coefficient
of tires adhesion. The cars with additional aerodynamic components producing high downforce
at high speeds can realize greater braking power. At high downforce values, the braking
efficiency is higher. However, the reduction of car’s speed during braking also reduces the
aerodynamic downforce and reduces the tire grip limit, the effect of which should be considered
when the brake foot-lever is actuated.
During braking, the inertia force counteracts the forces of aerodynamic drag and the tire
reaction force, which is dependent onvehicle weight, tire grip and the aerodynamic downforce.
When braking from high speeds, the operation of mechanical brakes is also supported byaero-
braking.
Effectof aerodynamics during cornering
When cornering, each vehicle has a critical speed related to road curvature. When cornering, the force of
inertia, directed outward the curve, must be balanced by the lateral forces generated by the tires. The force
transmitted by the tire depends on the vertical component of the load force acting on the tire.
The assumptions used in the simulation:
The aim of this studywas to analyse the influence of the shape, location and method ofgeometry
changes of a variety of deflected flaps on the generated aerodynamic forces. Since the operation
of such flaps may depend strongly on the shape of the body on which they are placed, a very
simple bodyshapewas selected to omit possibleinterferences with a too complicated geometry,
forexample with the wake behind the sidemirrors . Due to this assumption, all the results should
be only treated as a demonstration one showing and explaining physical processes taking place
during car’s operation, but not as the data directly applicable to different car geometries.
The analysis and numerical simulation have been done using the ANSYS-Fluent the basis for
the calculation was the geometry of the vehicle, similar in shape to those used in group C and

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race cars used on the Le Mans track. The basic geometry of the body has not been changed
during the calculation of the investigated flap versions. The car bodies differed only in the flap
dimensions, the place of their location, and the location of the flap’s axis of rotation. Figure 2
shows the basic geometry of the bodyof the vehicle used in the flow simulations.
Pressure distribution:
Any flow disturbance has a reason. Changes in pressuredistribution on the car bodysurface, as
well as formation of pressure gradients affect the character and behavior of the boundary layer.
The pressure distributions were visualized on the surface of the vehicle. Based on the pressure
contours, the value of the pressure drags, and aerodynamic downforce can be determined.

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CONCLUSION:
Movable aerodynamic elements of the car body were already used in the early days of racing
cars. In addition to moving wings, movable flaps were used on the Porsche in 1969-year model.
Flaps were placed on the rear edge of the body, which is in line with the present results of
numerical simulations. We have studied different papers, journals studied different ideas. There
are many ways of Aerodynamics Analysis on a car we choose simple aero flow on the middle
ofthe car. After choosingthe type offlow over the car we decided to create a modelby ourselves
with the help and guides of cad model designer. We learnt how to design basic and simple car
model in 3DXL or 3D experiences software.

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2. H. Ozawa, S. Nishikawa and D. Higashide Development of aerodynamics for a solar race
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DOI: https://doi.org/10.1016/s0389-4304(98)00019-8
3. A. Gelhaus and V. Ren. Drag and Driving-Stability-Related Aerodynamic Forces and Their
Interdependence-Results of Measurements on 3/8-Scale Basic Car Shapes. SAE Technical
Paper 860211(1986).
DOI: https://doi.org/10.4271/860211
4. D. Tomjanovich, D. Kozak. Ivanić and T. Bakari. CFD Analysis of conceptcar in order to
improve Aerodynamics. Campari innovation. 2011(1): 63-70.
5. D. Landman, J. Simpson and B. Hall. Use of designed experiments in Wind Tunnel Testing
of performance automobiles. (2002).
DOI: https://doi.org/10.4271/2002-01-3313
[6] M. Laneri, Best practice guidelines for handling automotive external aerodynamics with
FLUENT. Version 1. 2, Fluent Deutschland, Darmstadt, (2005).