COMPUTATIONAL ANALYSIS OF TWO DIMENSIONAL FLOWS ON A CONVERTIBLE CAR ROOF ABDULLAH B. MUHAMAD NAWI Report submitted in partial of the requirements for the award of the degree of Bachelor of Mechanical Engineering with Automotive Engineering Faculty of Mechanical Engineering UNIVERSITI MALAYSIA PAHANG JUN 2013
i UNIVERSITI MALAYSIA PAHANG FACULTY OF MECHANICAL ENGINEERING I certify that the project entitled Computational Analysis of Two Dimensional Flow On A Convertible Car Roof is written by Abdullah b. Muhamad Nawi. I have examined the final copy of this report and in my opinion, it is fully adequate in terms of language standard, and report formatting requirement for the award of the degree of Bachelor of Engineering. I herewith recommend that it be accepted in partial fulfilment of the requirements for the degree of Bachelor of Mechanical Engineering with Automotive Engineering. DR. AHMED NURYE OUMER Examiner Signature
ii SUPERVISOR S DECLARATION I hereby declare that I have checked this report and in my opinion this report is satisfactory in terms of scope and quality for the award of the degree of Bachelor of Mechanical Engineering with Automotive Engineering. Signature Name of Supervisor : MUHAMMAD AMMAR BIN NIK MU`TASIM Position : LECTURER Date : 26 JUN 2013
iii STUDENT S DECLARATION I hereby declare that the work in this report is my own except for quotations and summaries which have been duly acknowledged. The report has not been accepted for any degree and is not concurrently submitted in candidate of any other degree. Signature Name : ABDULLAH B. MUHAMAD NAWI ID Number : MH08081 Date : 26 JUN 2013
viii TABLE OF CONTENTS EXAMINER S APPROVAL DOCUMENT SUPERVISOR S DECLARATION STUDENT S DECLARATION ACKNOWLEDGEMENTS DEDICATION ABSTRACT ABSTRAK TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES LIST OF SYMBOLS LIST OF ABBREVIATIONS Page i ii iii iv v vi vii viii xi xii xiv xv CHAPTER 1 INTRODUCTION 1.1 Background 1 1.2 Problem Statements 2 1.3 Objectives 2 1.4 Scope of Study 2 CHAPTER 2 LITERATURE REVIEW 2.1 Computational Fluid Dynamics 4 2.1.1 General CFD 4 2.1.2 Governing Equation 5 2.1.2.1 RANS 2.1.2.2 Turbulence Flow and Turbulence Modelling 5 6 2.2 Aerodynamics of Vehicle 8 2.2.1 External Flow of Automotive Vehicle 9 2.2.2 Drag Coefficient 10
ix 2.2.3 Pressure Coefficient 2.2.4 Aerodynamic drag for Car Roof 11 12 CHAPTER 3 METHODOLOGY 3.1 Introduction 16 3.2 Flow Chart of Methodology 17 3.3 Prepare 2D Model of Convertible Car Roof 18 3.3.1 Overview 18 3.3.2 Solidworks Modelling Stage 18 3.4 Analysis Using CFD Simulation 21 3.4.1 Overview 21 3.4.2 ANSYS Simulation and Analysis Step 22 3.4.2.1 Geometry 3.4.2.2 Mesh 3.4.2.3 Setup 3.4.2.4 Results 23 23 24 26 3.5 Analysis of Simulation Result 26 CHAPTER 4 RESULTS AND DISCUSSION 4.1 Introduction 28 4.2 Result and Discussion 28 4.2.1 Total Pressure and Pressure Coefficient 28 4.2.2 Validation with The Experiment. 42 4.2.3 Drag Coefficient 43 4.2.4 Drag Coefficient vs. Pressure Coefficient. 45 CHAPTER 5 CONCLUSION AND RECOMMENDATION 5.1 Introduction 48 5.2 Conclusion 48 5.3 Recommendation 49
x REFERENCES 50 APPENDICES 52
xi LIST OF TABLES Table No. Title Page 3.1 Data for Wind Tunnel 20 3.2 Data for Model of convertible car 20 4.1 Data for Wind Tunnel 29 4.2 Total pressure and pressure coefficient of car roof for Model A 29 4.3 Total pressure and pressure coefficient of car roof for Model B 33 4.4 Total pressure and pressure coefficient of car roof for Model C 35 4.5 Total pressure and pressure coefficient of car roof for Model D 39 4.6 Drag force for all model 43 4.7 Drag Coefficient. 44
xii LIST OF FIGURES Figure No. Title Page 2.1 Streamline of external flows around a stationary vehicle 10 2.2 Effect of roof camber on drag coefficient (C D ) and absolute drag. 13 2.3 Drag coefficients of convertible 14 2.4 Aerodynamic resistance coefficient for passenger cars of various shapes 15 3.1 Flowchart of methodology 17 3.2 Four sketches of 2D model convertible car roof 19 3.3 Four type of 2D model convertible car roof before sketches 19 3.4 Example of Wind tunnel model 21 3.5 Workbench main window (Unsaved Project) 22 3.6 Design Moduler 23 3.7 Meshing 24 3.8 Setup Window for FLUENT 25 3.9 Define Run step 25 3.10 Contour of convertible car roof that show the change of pressure 26 4.1 Pressure coefficient for Model A in three situation of Wind Tunnel 32 4.2 Pressure coefficient for Model B in three situation of Wind Tunnel 35 4.3 Pressure coefficient for Model C in three situation of Wind Tunnel 38 4.4 Pressure coefficient for Model D in three situation of Wind Tunnel 41 4.5 Comparison the four models with experiment. 43 4.6 Drag Coefficient 45 4.7 Pressure Coefficient vs. Drag coefficient at medium point 46
xiii 4.8 Pressure Coefficient at maximum point vs. drag coefficient 46 4.9 Pressure Coefficient at minimum point vs. drag coefficient 47
xiv LIST OF SYMBOLS ρ V V o A P P atm C D C P F D μ U Re Density Velocity Wind velocity (reversed direction) Area Pressure Atmosphere pressure drag coefficient pressure coefficient Drag force Viscosity Dynamic viscosity Reynolds Number
xv LIST OF ABBREVIATIONS CAD CFD km/h m/s mm m kpa Pa Computational Aided Design Computational Fluid Dynamic kilometre per hour mile per second millimetre meter kilo Pascal Pascal