AN AERODYNAMIC STUDY ON MPV SPOILERAN AERODYNAMIC STUDY ON MPV SPOILER . ... (ANSYS). A simple model...

AN AERODYNAMIC STUDY ON MPV SPOILER

RAGUVARAN A/L JAYAHKUDY

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

AN AERODYNAMIC STUDY ON

MPV SPOILER


NAME : RAGUVARAN A/L JAYAHKUDY

MATRIC.NO : B041010046

COURSE : 4 BMCA

SUPERVISOR : NAZRI HUZAIMI BIN ZAKARIA

EVALUVATOR 1 : Mohd Haizal Bin Mohd Husin

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

AN AERODYNAMIC STUDY ON MPV SPOILER


This report is submitted in partial fulfillment

of the requirements for the award of the degree in

Bachelor of Mechanical Engineering (Automotive)

Faculty of Mechanical Engineering

University Teknikal Malaysia Melaka

MAY 2013

i

SUPERVISOR DECLARATION

“I hereby declare that I have read this thesis and in my opinion this report is sufficient in

terms of scope and quality for the award of the degree of

Bachelor of Mechanical Engineering (Automotive)”

Signature: ………………………

Supervisor: ....................................

Date: ....................................

ii

STUDENT’S DECLARATION

“I hereby declare that the work in this report is my own except for summaries and

quotations which have been duly acknowledged.”

Signature : ………………………..

Author : Raguvaran a/l Jayahkudy

Date : 31st

MAY 2012

iii

Dedicated to my beloved Father and Mother

iv

ACKNOWLEDGEMENT

I would like to take this opportunity to thank all who have rendered their full

support towards my “Projek Sarjana Muda” (Final Year Project) report. The pleasure,

the achievement, the glory, the satisfaction, the reward, the appreciation and the

construction of the report cannot be thought without a few or how apart from their

regular schedule, spared a valuable time for me. This acknowledgement is not just a

position of words but also as an account of indictment. They have been a guiding

light and source of inspiration towards the completion of the report. I am very

grateful to my Project Supervisor, Mr.Nazri Huzaimi Bin Zakaria for his kind and

timely help offered to me in execution of this project. Besides that, I would like to

thank my friends, and all my family members who with their valuable suggestions

and support, directly or indirectly helped me in the completion of this project.

v

ABSTRACT

Performance, handling, safety, and comfort of a car are significantly affected

by its aerodynamic properties. Getting high power directly from the engine is just not

enough to judge the performance of the car. Aerodynamic properties must be

considered for the purpose of studying the drag and stability performance of a car. In

order to improve a car’s aerodynamic drag and its stability, an aerodynamic device is

needed to perform such as the rear spoiler. Rear spoiler is an aerodynamic device that

functions to ‘spoil’ the unfavorable air flow across the body or in the scientific

explanation, to spoil the ‘laminar’ flow of the car’s aerodynamic movement in

motion. This rear placing device creates an area of high pressure to replace the usual

low pressure over the trunk resulting in increasing stability of the car. Basically, rear

spoilers are fitted at the trunk of a sedan car for its performance but does it gives the

same results if a rear spoiler were fitted in a Multi Purpose Vehicle (MPV)? Or just

for the sake of styling purpose. Thus, this report is regarding the effect of rear spoiler

on a MPV and the objective of this study is to investigate the aerodynamics on a

MPV vehicle with rear spoiler using CFD software (ANSYS). A simple model of the

MPV had been drawn using CATiA software; import it to ANSYS software and to

run the aerodynamic simulation.

vi

ABSTRAK

Sesebuah kenderaan yang bermutu tinggi bukan sahaja dipengaruhi oleh

keupayaan enjin sahaja, malah rekabentuk aerodinamik kenderaan tersebut juga amat

penting. Aerodinamik sesebuah kenderaan memberi impak kepada prestasi,

keselamatan, kawalan dan juga kestabilan kenderaan tersebut. Setiap kenderaan

mengalami kerugian tenaga disebabkan oleh daya tujah yang bertindak kepadanya

dimana daya tujahan keatas dan daya berlawanan dengan arah pergerakan kenderaan.

Bagi mengurangkan tindakan daya negatif ini, “spoiler” telah dibina oleh para

jurutera dan dipasang pada hampir setiap kereta di atas bonet belakang, dan amat

mudah untuk dilihat pada zaman sekarang. Kebanyakan pengguna tidak tahu tujuan

utama “spoiler” ini dipasang pada kenderaan malah ada yang meletakkan “spoiler”

atas dasar untunk mencantikkan kenderaan mereka sahaja. Secara asasnya, “spoiler”

dipasang bagi mengurangkan daya tujahan serta meningkatkan daya tekanan pada

bahagian belakang kereta agar ia lebih stabil ketika memandu pada kelajuan tinggi. Ia

terbukti pada kereta biasa tetapi adakah “spoiler” yang dipasang pada kenderaan jenis

“Multi Purpose Vehicle” MPV mampu memberi respon yang sama atau sekadar

tujuan kecantikkan ‘sporty’ sahaja. Tujuan projek ini adalah untuk mengkaji sejauh

mana respon “spoiler” ke atas kenderaan MPV dan jikalau ya, bagaimanakah

aerodinamik kenderaan MPV yang dipasang dengan “spoiler” berfungsi. Kajian CFD

pada struktur kenderaan MPV ber’spoiler’ dan tidak ber’spoiler’ akan dikaji

menggunakan perisian komputer (CATiA) dan akan disimulasi dengan menggunakan

perisian komputer (ANSYS).

vii

CONTENTS

CHAPTER CONTENT PAGES

SUPERVISOR’S DECLARATION i

STUDENT’S DECLARATION ii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES x

LIST OF FIGURES xi

LIST OF SYMBOLS xiii

LIST OF ABBREVIATIONS xiv

CHAPTER 1 INTRODUCTION

1.1 Project Introduction 1

1.2 Problem Statement 2

1.3 Project Objective 3

1.4 Project Scope 3

viii

CHAPTER 2 LITERATURE REVIEW

2.1 General Aerodynamic Concept 4

2.1.1 Definition of Aerodynamics 4

2.1.2 Automotive Aerodynamics 4

2.1.3 Drag & Lift concept 5

2.1.4 Drag Force 7

2.1.5 Lift Force 8

2.1.6 Downforce 9

2.2 Flow Separation Process 10

2.2.1 Laminar & Turbulent Flow 12

2.3 Boundary Layer 13

2.4 Rear Spoiler 15

CHAPTER 3 METHODOLOGY

3.1 Introduction 19

3.2 Modeling in CATiA Software 20

3.3 Analyzing in CFD Software (ANSYS) 23

3.3.1 ANSYS Simulation Process 23

3.3.2 Geometry 24

3.3.3 Meshing Process 25

3.3.4 Problem Setup 27

3.3.5 Solution 31

3.4 Assumptions 33

3.5 Problem Encountered 34

3.6 Overall Methodology of Final Year Project (PSM 1&2) 35

ix

CHAPTER 4 RESULTS & DISCUSSION

4.1 Simulation Results 36

4.1.1 Multi Purpose Vehicle without rear spoiler (MPV) 37

4.1.2 Multi Purpose Vehicle with rear spoiler (MPVs) 39

original full specification

(90degrees + 20cm length, 8cm height)

4.1.3 Multi Purpose Vehicle with rear structured spoiler 41

(MPVss) (100degrees + 50cm length, 8cm height)

4.2 Graphical Analysis 43

4.3 Comparison of MPV, MPVs & MPVss Model 44

CHAPTER 5 CONCLUSION & RECOMMENDATIONS 51

REFERENCES 53

APPENDICES 56

x

LIST OF TABLES

NUM. TITLE PAGE

4.1 Model’s properties at velocity, V=10m/s 44




xi

LIST OF FIGURES

NUM. TITLE PAGE

2.1 Aerodynamic flow of a MPV 5

2.2 Forces acting on an Aerofoil 5

2.3 Shear force and Pressure acting on the surface body 6

2.4 (3D) Modeled bodies 6

2.5 Value of Drag Coefficient of road vehicles 8

2.6 Basic Downforce principles 9

2.7 Pressure & Downforce acting on a vehicle spoiler 10

2.8 Flow Separation Process 12

2.9 Laminar & Turbulent Flow 13

2.10 Boundary Layer 14

2.11 Car Spoiler 15

2.12 Drag due to Pressure Differences 16

2.13 Effect of rear spoiler on lift 17

2.14 Level of pressure increase due to rear spoiler 17

3.1 View of a Porton Exora with Spoiler 20

3.2 Proton Exora’s Technical Specifications & Product Features 21

3.3 CATiA model (Proton Exora) without rear spoiler, named MPV 21

3.4 CATiA model (Proton Exora) with rear spoiler 22

original specification

[90degrees + 20cm length, 8cm height] named MPVs

3.5 CATiA model (Proton Exora) with structured spoiler 22

[100degrees + 50cm length, 8cm height] named MPVss

3.6 Fluid-Flow (FLUENT) system 24

3.7 “Wind-Tunnel” of the MPV model 25

xii

3.8 “Meshing Process” of the MPV model 26

3.9 “General Setup” of the MPV model 27

3.10 “Models & Materials “setup of the MPV model 28

3.11 Boundary Conditions “Velocity-Inlet & Pressure Outlet” 29

for the MPV model

3.12 Reference Values of the MPV model 30

3.13 Solution Methods, Controls & Initialization of the MPV model 31

3.14 Calculation Activities of the MPV model 32

4.1 Contours of Pressure on MPV model 37

4.2 Contours of Total Pressure on MPV model 37

(Maximum Pressure = 1152pa)

4.3 Contours of Velocity Magnitude on MPV model 38

(Maximum Velocity = 61m/s)

4.4 Contours of Turbulence Kinetic Energy on MPV model 38

(Maximum Kinetic Energy = 192.44m2/s2)

4.5 Contours of Pressure on MPVs model 39

4.6 Contours of Total Pressure on MPVs model 39


4.7 Contours of Velocity Magnitude on MPVs model 40

(Maximum Velocity = 60.8m/s)

4.8 Contours of Turbulence Kinetic Energy on MPVs model 40


4.9 Contours of Pressure on MPVss model 41

4.10 Contours of Total Pressure on MPVss model 41


4.11 Contours of Velocity Magnitude on MPVss model 42

(Maximum Velocity = 62.8m/s)

4.12 Contours of Turbulence Kinetic Energy on MPVss model 42


4.13 Graph of model’s Drag Coefficient 47

4.14 Graph of model’s Lift Coefficient 47

4.15 Graph of model’s Drag Force 48

4.16 Graph of model’s Lift Force 48

4.17 Fuel consumption formula 49

xiii

LIST OF SYMBOLS

p = Pressure

ρ = Air density

v = Vehicle’s speed

dFx = Net x-component of force

dFy = Net y-component of force

dA = Small element of surface area

τw = Wall shear stress

D = Drag

L = Lift

DA = Aerodynamic drag force

CD = Drag coefficient

A = Frontal area

LA = Aerodynamic lift force

CL = Lift coefficient

Tr = Air temperature

Pr = Ambient pressure

zs = Height of spoiler

W = Wingspan

H = Height of the wing

AoA = Angle of attack

Re = Reynolds Number

xiv

LIST OF ABBREVIATIONS

MPV = Multi Purpose Vehicle without spoiler

MPVs = Multi Purpose Vehicle with spoiler / original full specification


MPVss = Multi Purpose Vehicle with structured spoiler


CFD = Computational Fluid Dynamic

3D = Three Dimensional

SUV = Sport Utility Vehicle

F1 = Formula one

CAD = Computer Aided Design

ANSYS = Simulation Software

Fluent = Simulation System/Process

CATiA = Computer Aided Three-dimensional Interactive Application

1

CHAPTER 1

INTRODUCTION

1.1 PROJECT INTRODUCTION

Nowadays, the everyday cars and even Multi Purpose Vehicle (MPV) are

modified to look sportier and add some ‘looks’ to their ordinary vehicle by the owners

for many reasons. Having tremendous amount of power from the engine leads to higher

speeds for which the aerodynamics properties of the MPV given by the designer are not

enough to offer the required down force and handling. The performance, handling,

safety, and comfort of an automobile are significantly affected by its aerodynamic

properties. Extra parts are added to the body like rear spoilers, lower front and rear

bumpers, air dams and many more aerodynamics aids as to direct the airflow in different

way and offer greater drag reduction to a vehicle and at the same time enhance the

stability. Basically, aerodynamic styling of a vehicle is one of the most crucial aspects of

vehicles design a highly complex phenomenon [1] which encompassing the task of an

artful integration of advanced engineering and stylish aesthetics. A lot of emphasis is

laid on the aerodynamics of a vehicle [2] design as an aerodynamically well designed

vehicle spends the least power in overcoming the drag exerted by air and hence exhibits

higher performance – cruises faster and longer even on less fuel consumption [3]. Apart

from improved fuel economy, an aerodynamically superior vehicle offers better stability

2

and handling at highway speeds and also minimization of harmful interactions [4] with

other vehicles on the roadways.

Rear spoiler is a component to increase down force for vehicle especially

passenger car. It is an aerodynamic device that design to ‘spoil’ unfavorable air

movement across a car body. Main fixing location is at rear portion, depends on shape

of the rear portion either the MPV’s is square back, notchback or fastback because not

all rear spoiler can be fix at any type of rear portion of a MPV. Rear spoiler contributed

some major aerodynamics factor which is lift and drag. The reduction of drag force can

save fuel; moreover spoiler can also be used to control stability at cornering [5]. Besides

that, it even functions to reduce drag and reduce rear-axle lift.

1.2 PROBLEM STATEMENT

Basically, a car spoiler is used to stabilize the performance and get a better

response/control of a sedan car. Rear spoiler are fitted in the rear portion of a sedan car

in order to decrease the lift and drag force acting in the car by providing down force to

the vehicle so that the car gives a better response and control to the driver. Well does it

give the same response if the rear spoiler were fitted on a Multi Purpose Vehicle (MPV),

or act as a cosmetic purpose? Nowadays, we can see a lot of MPV were fitted with rear

spoiler for sportier look and as a “wow factor” in a lame looking MPV and thus, the

main task of this report is to analyze the response of a rear spoiler in a MPV. So, a case

study of the spoiler’s function on a MPV needs to be analyzed in order to gain all the

relevant properties using the Computational Fluid Dynamics (CFD) software (ANSYS).

Besides that, how much does the spoiler effect on an MPV’s performance is also need to

be taken into account.

3

1.3 PROJECT OBJECTIVE

This report is obliged according to the title of the project which is an aerodynamic

study on MPV spoiler. Before preceding this project study, several scopes and

objectives of this study have to be defined clearly and precisely. This is very essential in

order to carry out this study successfully. Therefore the objectives of this study are

mentioned below:-

To study an aerodynamics on MPV vehicle with spoiler using Computational

Fluid Dynamics (CFD) software.

To analyze the aerodynamics of the MPV spoiler using CFD software.

To design a simple MPV spoiler and to run the CFD simulation in order to

observe the flow of the aerodynamics.

1.4 PROJECT SCOPE

This report is conducted on certain limitation which was listed by the supervisor as

follows:-

To study an aerodynamics on a MPV without spoiler.

To study an aerodynamics on a MPV with spoiler.

To differentiate both design in terms of aerodynamic flow using CFD software.

4

CHAPTER 2

LITERATURE REVIEW

2.1 GENERAL AERODYNAMIC CONCEPT

2.1.1 Definition of Aerodynamics

Aerodynamics is a branch of Fluid Mechanics which concern on forces

generated on a body in a flow and thus the aerodynamics usually involves a lot of

calculation in various properties of the flow such as velocity, pressure, temperature,

density and even time. In order to calculate or approximate the forces and moments

acting on the bodies in the flow, we must understand the pattern of the flows [6].

2.1.2 Automotive Aerodynamics

Automotive aerodynamics is a type of study/analysis of the aerodynamic

characteristic of road vehicles which involves the related properties such as reducing

drag force, reducing lift force at high speed and preventing the wind noise. It is also

required to produce down force in order to improve traction and cornering abilities on a

road vehicle. Obviously, the shape of a vehicle does give enough response on the

5

aerodynamics characteristic. Figure 2.1 shows the basic view of the aerodynamics of a

Multi Purpose Vehicle (MPV)

Figure 2.1: Aerodynamic flow of a MPV

2.1.3 Drag & Lift concept

There are 2 basic categories of aerodynamics forces acting on a road vehicle

body which described as below and shown in Figure 2.2:-

1) Shear Stress – which acts parallel to the surface body and contributes to drag,

(also known as the component of aerodynamic force parallel to the wind)

2) Pressure – which acts vertically to the surface body and contributes to lift, (also

known as the component of aerodynamic force perpendicular to the wind).[7]

Figure 2.2: Forces acting on an Aerofoil

The resultant force of the shear stress and pressure distribution can be obtained

by integrating the effects of these 2 quantities on the surface body as shown below in

Figure 2.3.

6

Figure 2.3: Shear force and Pressure acting on the surface body

dFx = ( p dA) cos θ + ( τw dA) sin θ [Eq. 1]

dFy = - ( p dA) sin θ + ( τw dA) cos θ [Eq. 2]

Thus, the net x and y component of the force on the object are:

1) Resultant force in the direction of the upstream velocity is termed the drag,D

D= ∫ dFx = ∫ p cos θ dA + ∫ τw sin θ dA [Eq. 3]

2) Resultant force normal to the upstream velocity is termed of lift, L

L = ∫ dFy = - ∫ p sin θ dA + ∫ τw cos θ dA [Eq. 4]

For certain three dimensional (3D) modeled bodies as in Figure 2.4, there might

be also side force acting perpendicular to the plane containing Drag and Lift. The

resultant force can be divided into 3 components which are moment, drag and lift

coefficients but for this study, only drag and lift are to be considered.

Figure 2.4: (3D) Modeled bodies

7

2.1.4 Drag Force

An aerodynamic drag force is the force which opposes the forward motion of the

vehicle while the vehicle is in traveling mode and it acts externally on the body of the

vehicle. The drag force can be measured directly by simply attaching the body subjected

to fluid flow, to a calibrated spring and measuring the displacement in the flow

direction. Drag force is usually an undesirable effect, like friction and mostly engineers

are trying to minimize by creating many devices. Reduction of drag is closely associated

with the reduction of fuel consumption in automobiles, submarines and aircraft,

improved safety and durability of structures subjected to high winds and reduction of

noise and vibration [8]. More sophisticated drag-measuring devices called drag balances

uses flexible beams fitted with strain gauges to measure the drag electronically. Besides

that, it can be calculated using formulas [Equation 5] as shown below:

DA = ½ ρ v^2 CD A [Eq.5]

Where; CD = coefficient of Drag

A = frontal area (m2)

ρ = density of air [kg/m3]

v = velocity of vehicle [m/s]

The drag and lift forces depend on the density of the air, the upstream velocity of

the wind, and the size, shape, and orientation of the body are among other elements

which need to be taken into account. Therefore, it is more convenient to work with

appropriate dimensionless numbers that represent the drag and lift characteristic of the

body which is the drag coefficient. Modern road vehicles such as cars and MPV’s have

the value of coefficient of drag (CD = 0.2 - 0.4) [9]. The smaller the value of CD, the

better the aerodynamic flow of the vehicle. In general, the more blunt the vehicle, the

higher the drag coefficient as shown in Figure 2.5. As a result, the percentage of fuel

AN AERODYNAMIC STUDY ON MPV SPOILERAN AERODYNAMIC STUDY ON MPV SPOILER . ... (ANSYS). A simple model...

Documents

Transcript of AN AERODYNAMIC STUDY ON MPV SPOILERAN AERODYNAMIC STUDY ON MPV SPOILER . ... (ANSYS). A simple model...