CFD-BASED CAR BODY DESIGN OF THE WSU FORMULA SAE
RACE CAR
HAYDER SALEH 19094162
HARISHAN CHANDRA 19889607
MUSHTABA RAFYEE 19503455
Bachelor of Engineering Science
Supervisor(s)
Professor Richard Yang
School of Engineering, Design and Built Environment
Western Sydney University
April 2022
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Statement of Authentication
This thesis contains no material that has been accepted for the award of any other
degree or diploma and that, to the best of my knowledge and belief, this thesis
contains no material previously published or written by another person, except when
due reference is made in the text of this thesis.
Signature Hayder Saleh
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Date 22/ 04 /2022
Signature Harishan Chandra
Date 22 / 04 /2022
Signature Mushtaba Rafyee
Date 22 / 04 /2022
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TABLE OF CONTENTS
Abstract………………………………………………………………………………………………….(5)
Introduction……………………………………………………………………………………………(6)
Research Background ……….…………………………………………………………………....(7)
Literature Review………………………………………………………………………………..….(8)
Research Questions………………………………………………………………………..………(16)
Aims & Objectives…………………………………………………………………….……………(17)
Methodology……………………………………………………………………….…………………(18)
Preliminary Results ………………………………………………………..………………………(21)
References…………………………………………………………………..…………………………(31)
Proposed Timeframe………………………………………………………………..………….…(35)
Preliminary Conclusion…………………………………………..………………………………(36)
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ABSTRACT
In this project, the aim was to develop effective tools and practices for
design management to help in integrating all aspects of race car
construction and design. This project will be completed by a group of
students from the Western Sydney University.
Automobile manufacturers are increasingly focused on various aspects of
vehicle development cycle time reduction, weight reduction, and cost of
engineering design. CFD (Computational Fluid Dynamics) is often being
used to streamline these processes. CFD uses the flow of fluid and
numerical solution methods to help analyse various complex problems.
The Formula SAE was invented as it was made to help advance much
students' knowledge in the automotive industry helping create a better
future. By creating this project, it has helped several students improve
their knowledge about vehicles and the mechanics behind them.
The team utilised project and design management techniques, which
enabled Us to work more efficiently together. Successful integration of the
vehicles' systems was conducted, and the race car is now in its final stages
of construction.
This proposal will highlight the importance of CFD and how the methods
will help achieve the engineering design processes required for the
project. This proposal will help us design a body of high standards,
enabling us to successfully create an efficient race car body design for the
SAE team to be successful in the final competition.
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INTRODUCTION
This project will investigate the factors of achieving the maximum
effective design and management to achieve the greatest design by using
CFD (Computational Fluid Dynamics) car-based body. This involves
designing and constructing the body of the race car whilst reducing weight
and maximising the aerodynamics of the vehicle.
Formula SAE-A was found in Melbourne in 1927 to educate engineering
students about Automotive Engineering and how it can expand into many
engineering industries in the Asian Pacific region.
Aerodynamics has a considerable influence on how a car handles and
turns, and it may even improve its track performance. Many teams have
achieved this by using CFD-based car body design, which has significantly
improved their track performance.
The Race Car will be assessed in a competition, which will focus on the
quality of its design and aerodynamics. These developments will assess
how the designs of the body affects the performance on the track. The
implementation of all these designs and methods will be vital to allow us
to compete in the Formula SAE competition.
The aerodynamics is especially important as it affects how the car handles
and how it performs on the track. The aerodynamics of the vehicle will be
critical as it will affect the load on the tires which decides whether the
tires have more grip, allowing the car to accelerate faster, as well as it will
figure out the amount of resistance force being put against the vehicle.
By understanding the Fluid Dynamics in vehicles, this will allow us to
simulate the aerodynamics of the vehicle accurately, helping us figure out
the downforce, airflow, and resistance around the vehicle. We will be using
Solidworks to design the vehicle. Solidworks is a solid modelling CAD
software made by Dassault systems.
This proposal will highlight the research done and the methods integrated
to help achieve the engineering design processes required for the project.
This research will help us understand the designs needed for a highperformance standard, enabling us to successfully create an efficient race
car body design for the SAE team to be successful in the final competition.
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RESEARCH BACKGROUND
Formula SAE is a project where multiple students work together to create
and design and construct a race car. The race car will be driven in a
competition that will focus on the quality of the vehicle's design and how
the students have used their engineering background to design the perfect
vehicle.
Formula SAE-A was founded in Melbourne in 1927 to educate engineering
students about Automotive Engineering and how it can expand into many
engineering industries in the Asian Pacific region. The vision of the SAE-A
was to help the engineering professions in Australia by teaching various
technical skills and knowledge, whilst also encouraging research and
development. This was used to assess the students' knowledge in
automotive engineering. This competition has improved since 1927 and
has helped many students increase their knowledge in the mechanics of
the vehicles and their automotive knowledge.
This project is vital as it helps students advance their knowledge in the
automotive industry thus helping create better machinery for the future. By
competing in this project many students will have more knowledge about
how vehicles work and about the advantages and disadvantages of
vehicles.
Also, students who want to work in the automotive industry in the future
will have a better opportunity to find work in this area as they would have
had earlier experience creating and designing a race car. Not only does this
project help students but will also help improve the future of automobiles
as they will be able to create better vehicles that are both efficient and
more functional.
This project will help students to innovate an innovative design for the
vehicle that will be competing in the future. By creating these vehicles and
competing them together, the student will be able to learn from others’
creations and their design, whilst learning about how they can improve
upon their own design for their vehicle, thus improving their knowledge in
this industry.
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LITERATURE REVIEW
Formula SAE was made as a project to help students work together to
create and design a race car. For many years, the race cars that have been
designed with the thought of drag reduction and less weight for more
speed and the quality of the vehicle's design and how they can use their
engineering background to design it.
However, the aerodynamics of the formula SAE-A race car has been
overlooked. The importance of aerodynamics on a car's handling and
cornering ability is incredibly significant and can help improve their
performance on the track. To achieve this many teams have implemented
CFD-BASED car body design, which has significantly improved their
success on the track.
There are several research articles on the use of CFD designs and how they
can improve the aerodynamics of vehicles. The Author Simon McBeath
talks about the aerodynamic theories and how computational fluid
dynamics (CFD) techniques can affect the vehicle in his book ‘Competition
Car Aerodynamics’ in which he states ‘CFD is the analysis of systems
involving fluid flow, heat transfer and associated processes such as chemical
reactions using computer-based simulations.’ (McBeath, 2017). McBeath had
mentioned that the ‘density and temperature are thought of as invariable in
competition car aerodynamics (although both may be relevant in some
circumstances), and so in essence, CFD usually must calculate what the
changes in velocity will be around a given body.’ (McBeath, 2017).
This helps us understand that there are several calculations that must be
done before we can create a vehicle for a high-performance race. It says
how there are various external elements that must be taken into
consideration before designing the vehicle. We must also take into
consideration the environmental impact, energy efficiency, and safety of
developing vehicles, which Jo. Y. Wong has mentioned this in his book
Theory of Ground Vehicles. He has mentioned that there are several
engineering fundamentals to consider that have critical factors affecting
the performance and handling of vehicles.
We also must consider the various CAD and CAM (computer-aided
methods) designs and performance evaluation methods. Jo. Y. Wong
mentions that when applying engineering principles to many examples
and problems we can use various parts from CAD and CAM designs to help
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us understand and improve our CFD design for the car body, which in
return will help us create an effective performance vehicle. (Jo. Y. Wong
2008)
Likewise, Mohammad Arief Dharmawan, Ubaidillah, Arga Ahmadi Nugraha
have said that ‘One of crucial to achieving high performance is an
aerodynamic factor.” This tells us that it is vital for us to improve the
aerodynamics of the vehicle to be able to make a Formula SAE car with
high performance range. Furthermore, the downforce, lift, drag force, and
coefficient of drag are the most principal elements in aerodynamics. A
vehicle with a higher downforce which is when there is a negative lift will
have better aerodynamic performance. Dharmawan mentions that the lift
of a fast car is because the air that flows from in front of the vehicle at
high speed goes to the bottom of the car causing it to lift. In the race car's
aerodynamics, drag force is a crucial factor as it is the weight and pressure
that pushes the air in the opposite direction of its velocity, causing it to
slow down. (Dharmawan etc. 2018)
To reduce the effects on the vehicle we could add a few aerodynamic
devices to help improve its performance. Some aerodynamic devices that
can be used are the front wing, rear wing, and diffuser.(Ruhrmann,
A., Zhang, X. 2002) Aerodynamic devices are designed to help reduce the
lift and drag against the vehicle's body. McKay and Gopalarathnam have
undertaken various scientific methods to investigate how the addition of
wings can change the aerodynamics of racing vehicles. They have also
discussed the downforce and its importance in Formula vehicles and how
they react with the automobile balance due to its tyres air pressure,
especially when the vehicle is turning. (N. J. McKay, A. Gopalarathnam
2002)
D. G. Landinez had created an aerodynamic study, which told that the
diffuser is a crucial part of the vehicle as it slows the fluid moving
underneath the vehicle. This situation creates drag which can impede with
the vehicle motion. Due to this some race vehicles have implemented the
use of a smooth diffuser to keep the airflow of the car consistent, reducing
the effects on the vehicle. (D. G. Landinez 2013)
Bernoulli's Law states that the airflow velocity at the bottom of a vehicle is
larger than that at the top and as a result, the air pressure on the upside of
the vehicle will be greater than the air pressure on the bottom. This was
looked at by Pritchard and Leygian in which they said it will increase the
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downforce and prevent lift in the automobile. (P. Pritchard and J. Leylegian
2011)
According to Landinez's studies we can conclude that the diffuser shape
will be like a nozzle or a circular point top to reduce the drag and to
increase the downforce. By implementing Various CFD techniques to his
strategy we will be able to give the race vehicle more ground grip,
increasing the speed of the vehicle.
Similarly like the front wing, the rear wing is also a crucial part which will
influence the aerodynamics of the vehicle. Devaiah and Umesh state that
the rear wing contributes to a third of the car’s total downforce. (B. N.
Devaiah, S. Umesh 2013) By implementing CFD technique into the design
of the rear wing we will be able to find the perfect structure of the wing to
minimise the lift and maximise the downforce.
A CFD technique we can implement for the design of the wing of the
vehicle is using unstructured meshes that are blended with a boundary
layer mesh for multi-element wing to help employ efficiently. Creating
multi-element wing designs by using this method has been proven
successful by two engineers Lewis and Postle, who have shown that there
are many strategies that may be used to increase efficiency, but this
method has increased the level of precision necessary. (R. Lewis, P. Postle
2003). This type of meshing was evaluated and explained by using
experimental parameters which were figured out using Abbott and
Doenhoff results. The data showed that the lift and the drag when tracked
with the unstructured mesh had improved. If the change in these values
was less than 1%, mesh convergence was considered to have been
achieved. They used the Spallart Almaras and Reynolds Stress turbulence
models for the CFD lift and drag computations and the results were
compared to a NASA wind tunnel experiment. (I.H.Abbott, A. E. Von
Doenhoff 1959)
The design process was to analyse the element that makes the wings using
the same meshing techniques. According to Katz, increasing the number of
components slows flow separation while boosting lift. (J. Katz 1995) As a
result, it is essential to do research into multi-element wings to find the
best design. From these publications we can see that there are many
external factors that we will have to acknowledge as well as research and
improve the three wings which are the front wing, middle wing, and rear
wing.
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Cornell University completed three different experiments about the
advantages of CFD developed front and rear wing packages. They
experimented with the aerodynamics of an underbody-equipped bluff body
of a motorcycle engine which was surrounded by interfering objects:
wheel, forks, frame etc. These experiments were conducted using both
racing cars and high-speed vehicles. To help gather the results we see that
one design is more valid and useful. The university used both wind tunnel
experiments and CFD simulations to understand whether there were any
agreements between the two. They found that some aspects of the
experiment agreed with each other over several applied situations. (Desai
et al. 2008)
The CFD values for lift coefficient were measured within 15-25 percent of
experimental instances. (Desai et al. 2008) The findings showed that the
flow configurations of the ride heights were comparable to those used in
the study. It also improved the downforce which decreased the drag. The
separation of the underbody and ground boundary layers at the diffuser,
had effects that showed the underbody vortices on downforce production
and stall avoidance at low ride heights were examined in depth using
various CFD model results. (Desai et al. 2008)
To complete their experiments Desai used a commercial CFD tool ANSYS
Fluent 6.3.26. This software is used for modelling fluid flow and heat
transport with complicated geometries using computer-aided engineering
tools in Computational Fluid Dynamics (CFD). This method was
implemented to examine how a bluff body interacts with the stationary
ground plane and other bodies. Their goal was to find relevant,
dependable, and valuable results while reducing computational
requirements, mesh construction time, and software user experience.
(Breslouer, O. J., & George, A. R. 2008)
A similar thing can be seen by the Formula Mazda racing team, who also
have used CFD to help design their racing vehicle. The Mazda team used
Star-CD Computational Fluid Dynamics (CFD) code, to help design their
vehicle. The way the Mazda team made their front wing assisted with
slightly decreasing negative lift, this resulted due to the air flow speed
increasing over the wings, however there was a slight increase in the drag
due to the increased velocities around the wing. (Kieffer, W., Moujaes, S., &
Armbya, N. 2006) To reduce the effect of this Ranzenbach, made a
calculation that showed calculating the grid should be three times the
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chord length from the trailing edge, and should be 1.75 times the chord
length downstream from the intake.(Ranzenbach, R., & Barlow, J. B. 1994)
George, Zhang, and a few other engineers emphasised the relevance of
downforce and stall avoidance. The importance of avoiding underbody lift
and stalling showed that the diffusers of the vehicles had an influence on
the ride height and diffuser angle. This affects the aerodynamic elements
surrounding the vehicle and has a considerable influence on flow around
it.(George, Albert R., J.E. Donis. 1983)
Another way to improve the aerodynamics of the vehicle would be to
design a vehicle with a more streamline design like the aerodynamics
design of a F1. Katz mentions that ‘streamlining would seem to be important
- after all, we want the car to move more easily through the air (less drag =
faster) - but the most dominant reason ehin the significant difference in the
appearance of the more recently designed multi winged race car is the focus on
using its body and wings to create aerodynamic downforce.’ (J. Katz 1995)
Katz has shown how we should try to make a more streamline design to
reduce the drag of the vehicle, as well as improve the downforce of the
vehicle which has a lot of advantages. He has also mentioned that
‘Aerodynamic downforce increases loads on the tires without increasing the
vehicle's weight! The result is increased cornering ability with no weight
penalty, which gives a reduction in lap times.’ (J. Katz 1995).
Computational Fluid Dynamics (CFD) helps design tools that could analyse
the complex problems that will arise with a race car that would typically
require extensive resources. The Use of Computational Fluid Dynamics for
the Design of Formula SAE Race Car Aerodynamics by Punith Doddegowda,
Aleksandr L. Bychkovsky and Albert R. George, released in 2006, proves the
significance of aerodynamics for the Formula SAE race car. The results
from this paper show us that ‘the coefficient of lift can be predicted
accurately to within 10% of the experimental value, but the coefficient of drag
is not predicted very well.’ The authors have also expressed that
‘Computational Fluid Dynamics can be used for the development of an
aerodynamics package for a race car even with limited computing resources.
Simple CFD evaluations supply the first base from which promising designs can
be picked and evaluated in the wind tunnel.’ The main conclusions drawn from
this paper are as follows.
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1. Right 2D and 3D CFD evaluations can be performed by race teams for
aerodynamics thus accelerating the design cycle by supporting wind tunnel
tests.
2. The prediction of coefficient of lift for air foil design was found to be within
10% of the experimental value, but the coefficient of drag was not predicted
very well.
3. The accuracy of CFD calculations depends on mesh refinement and hence
more extensive computing resources can lead to better results. (Punith
Doddegowda, Aleksandr L. Bychkovsky and Albert R. George 2006).
Predicting aerodynamic forces for racing vehicles is a perplexing task that
requires calculating the lift force in addition to drag force. CFD allows us
to estimate to a certain degree although less right predictions. The lift
force is the vertical part of pressure over vehicle bottom, are reflected in
the lift force. The impact of this can cause errors on figuring out the drag
force, which are reduced since the projected area in the vertical direction is
less. (Rajneesh Singh 2008)
Many investigations have compared any commercial CFD software to
decide what is the best. Most engineers have improved their results,
commonly by using several computers aided design (CAD) and
computational fluid dynamics (CFD) tools.
Solidworks was a quite common software used to construct CAD models of
all the vehicles bodies. Most engineers had prepared the CAD files and
assessed them on Gambit. Gambit is a tool that is used for producing
geometry and meshes with computational fluid dynamics (CFD). Gambit is
a system interface used for creating and meshing geometries together and
creating them in one location. The models produced from Gambit were
then imported into Fluent. Fluent is a software used for modelling the flow
of fluids and the heat transport using computer-aided engineering tools in
Computational Fluid Dynamics (CFD). All these systems were implemented
for the simulations and post-processing of the vehicle. (S. Desai, Lo and R.
George 2008)
Other software that has been used are CREO, CATIA and NASTRAN. Creo
allows the users to create 2D CAD, 3D CAD, parametric and direct
modelling capabilities as well as it has extensions to develop, analyse,
visualise, and share designs downstream. Catia is software that was
developed by the creators of Solidworks, to help with computer-aided
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design, computer-aided manufacturing, computer-aided engineering, 3D
modelling, and product lifecycle management. Nastran is a program
developed by the United States government that funded the development
of an analytical programme for NASA, this was used as it can solve stress,
vibration, structural failure, heat transfer, acoustics, nonlinear, and
aeroelasticity analysis. These CFD software’s were used by Girish Mekalke
an engineer in the Vadodara Institute Of Engineering India.(Mekalke, G.
2020)
It is much more difficult to decide the stiffness of suspension components
than the frame. According to Reid F. Allen, in his own words, “the stiffness,
or compliance of each component must be known to ensure that the
suspension remains within an acceptable range of the optimal under all
conditions.” (Reid F. Allen 2009) The findings show that by doing this,
many tuning problems can be avoided later.
Intake restrictors are particularly important in the construction of a
formula SAE car engine. The main purpose of a restrictor is by restricting the
mass flow to the engine, the maximum power is reduced. “A venturi in itself can
allow a maximum of 0.0703 kg/s of airflow to the engine, considering no
losses in friction and turbulence” (Pranav Anil Shinde 2014). The composer
highlights the importance of using a restrictor. The author makes a good
point on how the mass flow passing can be restricted by having an intake
manifold of a formula SAE engine, fitted with a Ventura restrictor.
Various numerical systems are periodically checked for accuracy using
turbulent flow over a rearward facing step. A recirculation zone directly
downstream of the step is the key feature. Numerical approaches have had
difficulty predicting the length of reattachment. In this article, the concept
of incompressible flow over a retrograde step is briefly discussed. The
measurements were collected on a backward-facing step, so the
equipment that they used in their research prohibited them from seeing
the recirculating flow in detail. Due to this the current experimental
analysis reveals a lot of features that have a separation. After they
reattached, the flow returned to a normal turbulent boundary layer
structure. The rapid changes of the velocity in the inner layer's surface led
to a low mean-velocity gradient and, as a result, a drop below the
universal log-law was detected. (Kim, J., Kline, S. J., & Johnston, J. P. 1980).
Using a mixed volume unstructured flow solver, a newly developed
nonlinear turbulence model was successfully implemented to evaluate for
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two turbulent swirling flows and a non-swirling backward facing step flow.
The results for the rotating pipe flow, show that the non-linear cubic
turbulence model makes a significant improvement for the fully developed
swirling velocity profiles. The cubic model predicts improved flow features
downstream of the recirculation zone for confined swirling coaxial jets,
while there is no substantial difference between the results expected by
the cubic and SKE models before the recirculation zone. The backwards
facing step flow shows that using the cubic turbulence model to predict
non-swirling flow computations is not harmful. When compared to
experimental data, the cubic model predicts the length of the separation
bubble better than the SKE model. The grid sensitivity issues were also
investigated using the step flow. If the grid resolution is carefully selected
at the high gradient zone, both the quadrilateral and triangular meshes can
predict acceptable outcomes.
Formula SAE was set up to design and build a race vehicle. For many years
Race cars have been designed with the purpose of lowering the drag and
weight to boost speed, the Formula SAE-A race car's aerodynamics, on the
other hand, have been made to help improve the Aerodynamics factors and
how it has a significant influence on how a car handles and turns, and it
may even improve its track performance. CFD-based car body design is a
new technique being used to significantly improve the vehicles of the SAEA. Although it is a very new system it is vital as it has affected the
performance of vehicles on the track.
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RESEARCH QUESTIONS
1.
2.
3.
4.
5.
6.
7.
How important is it?
What is Formula SAE?
What is CFD?
How does CFD aid in everyday life?
What software is best for modelling CFD?
How does the wings affect the speed of the vehicle?
Why is the front wing and the rear wing so crucial in influencing the
aerodynamics of the vehicle?
8. What is downforce?
9. What is Drag?
10.
What is Aerodynamics?
11.
How does Aerodynamics influence the automobile industry?
12.
What is the importance of avoiding underbody lift?
13.
How does the diffusers of a vehicle influence the ride height
and diffuser angle?
14.
Why is predicting aerodynamic forces for racing vehicles an
arduous task?
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AIMS & OBJECTIVES
The aim of this project is to create a best formula SAE race car for WSU to
compete in the Formula SAE competition. Our group's specific aim will be
to design a CFD-BASED car body design that is convenient, aerodynamic
whilst also being systematic. Our aim is to successfully achieve these goals
so that we can compete in the Formula competition. There are many ideas
that need to be incorporated into the design to help achieve the maximum
efficiency of the vehicle. Some objectives we are striving to achieve is
creating an aerodynamic design, a comfortable design that does not
constrict the drivers movement, a design that keep the vehicle firm on the
ground, a weightless vehicle without removing essential components, a
design that has good airflow to keep the vehicles engine cool reducing
overheating, whilst also making the vehicle look of a high standards and
satisfying to the eye.
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METHODOLOGY
The first step in resolving the problem is to have a better awareness of all
accessible solutions and do research. Developing a solution to the
proposed issue begins with an understanding of all the options and
research that is currently available. As shown in the literature review
above, there are several design processes that we can follow to achieve
the optimal performance for the vehicle. We will need to make various
Design Scope and Contents as well as Design Methods to help design a
CFD design. Some of the initial data that we must collect should include
the type of material used on the body, other data should include the
structure of the design and how it affects the aerodynamics of the vehicle.
To collect this data, we should have multiple different types of material
and body design attempts and then select the overall best model. After the
initial data collected, we will have to graph our result so that we can select
the best model which would help us gain a better advantage of what task
needs to be accomplished, and then compare this to the Formula SAE
competition rules. Collecting data on the type of material as well as the
design is important to see if the implemented designs have allowed for an
increase or decrease in the overall vehicle performance.
To begin, we will need to construct a completely CFD body design for the
vehicle. To ensure that we design the optimal design we must begin
developing, evaluating, and adjusting the design of the body as soon as
possible. There are various components to consider while designing a
whole CFD body. It is best to begin with the most basic component of the
CFD Design, the Front and Rear Wing, which we can work through the two
components one by one. Although it can be time-consuming and costly to
change the wing if there is a design flaw, overall, the components will be a
key design feature that can determine the difference between winners and
losers. The next step should be to start testing and improving overall
system performance, usually through digital software. We must calculate
the raw weight, considering the height, length, and thickness, as well as
design possibilities based on the vehicle's structure. All these methods
must be included in the process of designing the final model.
Digitally modelling the Wings with the use of various software can offer
many benefits, including lowering the cost of production, evaluating the
experimental designs digitally and potentially being alerted to mistakes
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and flaws before creating a physical product. These days there are several
modern technologies that allow to produce virtual prototyping that can
also be assessed digitally to help determine whether the designs have any
benefits or negatives, before creating it in real life.
Another benefit of utilising software’s is that it allows engineering
companies and students like us to create a prototype digitally and assess it
on the software to help discover the benefit of the design as well as the
negatives. It also has a higher chance of eliminating human error, as it will
show the flaws of the design as well as providing graphs and tables of
information. Some disadvantages of using modern software’s are that they
require the design of the body to be accurately constructed by the
engineer for the software to obtain reliable predictions and forecast
reliable performance outcomes. As a result of this disadvantage,
competitors/engineers with little expertise or experience with both CAD
AND CAM software, will struggle as well as the fact that there is only a
limited choice of good software’s that is great with the designing of the
body. Another disadvantage is that many decent software is of high cost
and will struggle to be compatible with other company software’s, which
will create several challenges.
The Formula SAE competition rules can be met by creating a respectable
design and an aerodynamic body to fit the vehicle. A Rear wing is one
method that reflects on the aerodynamics of the vehicle and is usually
more efficient than a vehicle without a rear wing. This report will focus on
the aspects of CFD Airfoil Analysis of Front and Rear Wing Design, and
which certain designs can offer the best performance. After having
reviewed the literature review in depth we must select the best designs for
the vehicle.
As a result, We can determine that the vehicle must have a Wing attached
to the back of the vehicle to help increase its aerodynamics whilst keeping
it flat on the track. The more we invest in the research of a wing design,
we will be decreasing our air resistance, as well as providing a higher
aerodynamic wind flow, lowering the resistance against the vehicle.
Increasing the size of the wing will increase the aerodynamics of the
vehicle however it may increase the vehicle weight making the engine
work harder for it to move. Another method we can do is to increase the
length of the wing to help enhance its aerodynamic performance, however
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shorter length wings allow for the vehicle to be more flexible and have a
smaller air resistance pushing against it, which will improve the air
resistance but increase the air pressure against the vehicle as it has a
larger body. The ideal way to choose the measurements for the wings is to
use a software that will allow virtual testing and can determine the
amount of resistance and aerodynamics that can be achieved with the
adjustment of the diameter and length to help determine the best
performance potential.
The material we can use for both the rear and front wing is a full carbon
fibre composite design or we can also use an aluminium alloy 7075.
Carbon Fibre, which is often also known as graphite fibre, is a polymer.
This Polymer is an extremely robust and lightweight material which is five
times stronger and two times stiffer than regular steel. Carbon fibre is
made up of tiny carbon-based fibres usually with a diameter of 5 to 10
micrometres and has a high carbon content. Some positives of utilising
Carbon fibre are that it has High stiffness, high tensile strength, high
strength-to-weight ratio, highly chemical resistance, high temperature
tolerance, and many more. Carbon fibre price can vary however it tends to
to be made using Polyacrylonitrile, which is a non-aerospace grade
material and these only costs around $21.5/kg.
Another material we can use for the rear and front wing is an aluminium
alloy 7075. Aluminium alloy 7075 is made up of a mix between Zinc and
aluminium alloying elements. The 7075 aluminium alloy possesses many
positives such as it has a great ductility, strength, toughness, and fatigue
resistance, among other mechanical properties. This type of material is
commonly used on Aeroplane wings as the Wings and fuselages main
composite, this is due to its strength and low weight properties that make
it useful in a variety of applications. The average cost for this type of
material is about USD 0.15 to USD 812.69 which is 0.21 AUD to 1132.25
AUD per kg.
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Preliminary Results
We have currently not had any experimental findings as we are still in the
first stages of the design of the CFD car Body. Due to this, we can only use
other company’s performances from external resources. One major
problem many automotive vehicles endure is drag, this is a major problem
in the automotive industry. Modern day vehicle companies use various
types of computer simulations to find solutions to this problem, compared
to the past where this type of simulations was unavailable due to its
complexity and cost.
For many years, the external design of cars has developed in a variety of
shapes to suit a few reasons, including for its safety, comfort, and aesthetic
looks. For many years, companies had ignored the effects of air resistance
and drag based on automotive aerodynamics. However due to an oil crisis
in the 1970s, this situation changed drastically, and many automotive
companies rethought their design to help overcome this factor. Two
experiments were done on bluff bodies, by two engineers, the first one by
Morel in 1978 and the second by Ahmed in 1984. They both had similar
results however there were slight changes. They both designed a vehicle
that had the same dimensions of a real car but had increased the
sharpness of the angular edges. They had a length/width/height ratio of
3.33/1.5/1. In both cases, the rear base was changed by adjusting the slant
angle, by using the Reynolds values which are 1.4 x 10^6 and 4.29 x 10^6.
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Their results were quite similar however were still different. This can be
seen in the next picture which shows their results.
As we can see in the image above The results, although looking similar,
were quite different. This showed that Ahmed Design had a better
aerodynamics flow of the vehicle. From this experiment many companies
started to implement these strategies and started to reduce their drag.
This can be seen in the figure below
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As we can see the drag coefficient had reduced for various automotive
companies.
One such vehicle that used these results to obtain a low drag was the
Peugeot 206.
Peugeot has used both the experimental result and implemented these
results onto a digital system so that they were able to consider the effect
of the wind on the vehicle without physically creating a real vehicle.
One method that many companies use to increase their aerodynamics is
the utilisation of a front and rear wing. The Formula Mazda race car had
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done research about how the wings affect their performance on the track.
The front wing of the Mazda Formula car is made up of two parts, one on
each side of the fibreglass nose. They used this method of designing their
wing as it had an increase in the angle of attack and had a major influence
on the ground by reducing the lift and drag of the car's front wing, as well
as the rear wing. To evaluate their result Mazda used the Star-CD
Computational Fluid Dynamics (CFD) algorithm to build up and execute
their design. By using this method, they were able to determine many
factors that may affect their performance on the track. Their results can be
seen in the next few figures.
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The results that they made through the computer simulations were
collated and depicted graphically. The next figure charts show the
magnitude of the air velocity in different parts of the vehicle. It also shows
the coefficient of pressure which is plotted against the normalised
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pressure in the same way to create a pressure distribution.
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Another Research about how CFD-Based Shape Optimisation can improve
upon a vehicle Aerodynamics was Published by the SAE International in
the United States called ‘CFD-Based Shape Optimization for Optimal
Aerodynamic Design.’ This research focused on developing
various different practises and examining ways using a software made by
the company ANSYS called Fluent's which is a commercially accessible
software used for CFD simulations. Some of their results had shown many
positives as well as a major increase in the aerodynamics of their vehicle.
Their results can be seen in the graphs provided.
They also used a variety of numerical values and equations to obtain their
optimum vehicle standards, as can be seen in the following tables.
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Proposed Timeframe
TASK
TOPIC SELECTION
ABSTRACT/INTRODUCTION
DESIGN/RESEARCH
BACKGROUN
CRITICAL LITERATURE
REVIEW
RESEARCH QUESTIONS
AIM/OBJECTIVES
RESEARCH METHODOLOGY
PRELIMINARY RESULTS
PRELIMINARY
CONCLUSIONS
TIMELINE
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WEEK 1
WEEK 2
WEEK 3
WEEK 4
WEEK 5
WEEK 6
WEEK 7
WEEK 8
WEEK 9
WEEK
10
WEEK
11
WEEK
12
WEEK
13
WEEK
14
Preliminary Conclusion
In Conclusion this study investigates the components that contribute to an
effective design and management using a CFD (Computational Fluid
Dynamics) car-based body. This entails designing and building the racing
car's body to improve aerodynamic performance, and how it has a
substantial impact on how cars handle. Many companies have adopted the
CFD-based vehicle design, which has increased their performance
dramatically. Our Race Car will be judged in a competition that focuses on
the design and aerodynamics of the vehicle. This report has shown how a
vehicles aerodynamics is essential and it change on how the car performs
on a racetrack. Aerodynamics of a vehicle is important as they affect the
load on the tyres, as well as the amount of resistance force given to the
vehicle. Understanding Fluid dynamics in automobiles enables us to
perfectly replicate a vehicle's aerodynamics, allowing us to compute
downforce, airflow, and resistance in the vehicle. This proposal has
emphasised the research that was conducted as well as the approaches
that were used to aid with the project's engineering design procedures.
This study has supplied a better understanding of the designs necessary for
a high-performance vehicle, aiding us to create an aerodynamic racing
vehicle body design for the SAE team to compete in the final competition.
The outlook of the activities next step is to work on the physical car and
simulate the results gathered on a digital software to figure out the
optimal design.
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