COMPUTATIONAL ANALYSIS OF TWO DIMENSIONAL FLOWS ON A CONVERTIBLE CAR ROOF ABDULLAH B. MUHAMAD NAWI

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1 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

2 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

3 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

4 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

5 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 Problem Statements Objectives Scope of Study 2 CHAPTER 2 LITERATURE REVIEW 2.1 Computational Fluid Dynamics General CFD Governing Equation RANS Turbulence Flow and Turbulence Modelling Aerodynamics of Vehicle External Flow of Automotive Vehicle Drag Coefficient 10

6 ix Pressure Coefficient Aerodynamic drag for Car Roof CHAPTER 3 METHODOLOGY 3.1 Introduction Flow Chart of Methodology Prepare 2D Model of Convertible Car Roof Overview Solidworks Modelling Stage Analysis Using CFD Simulation Overview ANSYS Simulation and Analysis Step Geometry Mesh Setup Results Analysis of Simulation Result 26 CHAPTER 4 RESULTS AND DISCUSSION 4.1 Introduction Result and Discussion Total Pressure and Pressure Coefficient Validation with The Experiment Drag Coefficient Drag Coefficient vs. Pressure Coefficient. 45 CHAPTER 5 CONCLUSION AND RECOMMENDATION 5.1 Introduction Conclusion Recommendation 49

7 x REFERENCES 50 APPENDICES 52

8 xi LIST OF TABLES Table No. Title Page 3.1 Data for Wind Tunnel Data for Model of convertible car Data for Wind Tunnel Total pressure and pressure coefficient of car roof for Model A Total pressure and pressure coefficient of car roof for Model B Total pressure and pressure coefficient of car roof for Model C Total pressure and pressure coefficient of car roof for Model D Drag force for all model Drag Coefficient. 44

9 xii LIST OF FIGURES Figure No. Title Page 2.1 Streamline of external flows around a stationary vehicle Effect of roof camber on drag coefficient (C D ) and absolute drag Drag coefficients of convertible Aerodynamic resistance coefficient for passenger cars of various shapes Flowchart of methodology Four sketches of 2D model convertible car roof Four type of 2D model convertible car roof before sketches Example of Wind tunnel model Workbench main window (Unsaved Project) Design Moduler Meshing Setup Window for FLUENT Define Run step Contour of convertible car roof that show the change of pressure Pressure coefficient for Model A in three situation of Wind Tunnel Pressure coefficient for Model B in three situation of Wind Tunnel Pressure coefficient for Model C in three situation of Wind Tunnel Pressure coefficient for Model D in three situation of Wind Tunnel Comparison the four models with experiment Drag Coefficient Pressure Coefficient vs. Drag coefficient at medium point 46

10 xiii 4.8 Pressure Coefficient at maximum point vs. drag coefficient Pressure Coefficient at minimum point vs. drag coefficient 47

11 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

12 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