DESIGN & DEVELOPEMENT OF AN AERODYNAMIC PACKAGE FOR A FSAE RACE CAR Diploma Thesis by Ioannis Oxyzoglou Supervisor: Nikolaos Pelekasis Laboratory of Fluid Mechanics & Turbomachinery Volos, Greece - May 2017 Approved by the tree-Member Committee of Inquiry: 1st Examiner: Dr. Pelekasis Nikolaos Professor, Computational Fluid Dynamics [email protected] 2nd Examiner: Dr. Stamatelos Anastasios Professor, Internal Combustion Engines [email protected] 3rd Examiner: Dr. Charalampous Georgios Assistant Professor, Thermofluid Processes with Energy Applications [email protected] © Copyright by Ioannis Oxyzoglou Volos, Greece - May 2017 All Rights Reserved 2 ABSTRACT This Thesis describes the process of designing and developing the aerodynamic package of the 2016 Formula Student race car (Thireus 277) of Centaurus Racing Team with the use of CAD Tools and Computational Fluid Dynamics (CFD). It further investigates the effects of aerodynamics on the vehicle's behavior and performance with regard to the Formula Student competition regulations. The methods used during the development are evaluated and put into context by investigating the correlation between the CFD results of the car model and the lap-time simulated counterpart. The aerodynamic package consists of a nosecone, two sidepods, an undertray, a front and a rear wing. The Thesis details all the stages involved in designing and optimizing these components to achieve the desired results and maximize the amount of performance enhancing aerodynamic downforce generated by the aerodynamic package, while maintaining drag force at low levels. 3 CONTENTS 1. INTRODUCTION ............................................................................................ 7 2. AERODYNAMICS OF A FSAE RACE CAR .......................................................... 8 2.1. Introduction to Race Car Aerodynamics ........................................................ 8 2.1.1. Downforce .................................................................................................. 8 2.1.2. Drag Force .................................................................................................. 9 2.1.3. CL, CD Coefficients ..................................................................................... 10 2.1.4. Wings Theory ............................................................................................ 11 2.1.5. Venturi & Ground Effects ......................................................................... 14 2.2. FSAE Aerodynamic Devices .......................................................................... 16 2.2.1. Nosecone .................................................................................................. 16 2.2.2. Front wing ................................................................................................. 18 2.2.3. Rear Wing ................................................................................................. 21 2.2.4. Undertray Diffuser .................................................................................... 24 2.2.5. Sidepods ................................................................................................... 27 2.2.6. Brake Cooling Ducts .................................................................................. 29 2.2.7. Flip-Ups ..................................................................................................... 30 2.2.8. Suspension Wishbone Covers .................................................................. 31 2.3. Aerodynamic Forces Distribution & Balance ................................................. 32 3. SETUP OF THE CFD MODELS ........................................................................ 36 3.1. pre-Processing ............................................................................................. 37 3.1.1. Geometry “Clean-up” ............................................................................... 37 3.1.2. Creation of Fluid Domain ......................................................................... 38 3.1.3. Mesh Creation .......................................................................................... 39 3.1.4. pre-Processing of the CFD Models for the Aerodynamic Package .......... 44 3.2. Solving Process ............................................................................................ 57 3.2.1. General Settings ....................................................................................... 58 3.2.2. Viscus Models ........................................................................................... 60 3.2.3. Boundary Conditions ................................................................................ 63 3.2.4. Reference Values ...................................................................................... 67 4 3.2.5. Solution Methods ..................................................................................... 68 3.2.6. Solution Controls ...................................................................................... 71 3.2.7. Monitors ................................................................................................... 72 3.2.8. Solution Initialization ................................................................................ 73 4. CFD SIMULATIONS RESULTS ANALYSIS ........................................................ 75 4.1. Nosecone .................................................................................................... 75 4.1.1. Horizontal Nosecone ................................................................................ 75 4.1.2. Vertical Nosecone..................................................................................... 76 4.1.3. Angled Nosecone ...................................................................................... 77 4.1.4. Final Nosecone ......................................................................................... 78 4.1.5. Results Comparison .................................................................................. 79 4.2. Undertray .................................................................................................... 80 4.2.1. Single Diffuser ........................................................................................... 80 4.2.2. Separated Rear Diffusers with Splitter ..................................................... 81 4.2.3. Separate Rear Diffusers ............................................................................ 82 4.2.4. Side Diffusers ............................................................................................ 84 4.2.5. Side & Double Diffusers ............................................................................ 86 4.2.6. Results Comparison .................................................................................. 89 4.3. Sidepods ..................................................................................................... 90 4.3.1. No Sidepods .............................................................................................. 92 4.3.2. Lowered Sidepods .................................................................................... 93 4.3.3. Lifted Sidepods ......................................................................................... 94 4.3.4. Final Sidepods ........................................................................................... 95 4.4. Wings .......................................................................................................... 98 4.4.1. Front Wing ................................................................................................ 98 4.4.2. Rear Wing ............................................................................................... 104 4.5. Whole Car Models ..................................................................................... 108 4.5.1. Model without an Aerodynamic Package .............................................. 108 4.5.2. Model with Undertray & Sidepods ......................................................... 112 4.5.3. Model with a Full Aerodynamic Package ............................................... 116 4.5.4. Results Comparison ................................................................................ 121 5. LAP-TIME SIMULATIONS & VALUATION OF THE RESSULTS ........................ 123 5.1. Without Aerodynamic Devices ................................................................... 124 5 5.2. Undertray & Sidepods ............................................................................... 125 5.3. Full Aerodynamic Package ......................................................................... 127 5.4. Track Results Comparison .......................................................................... 128 6. BIBLIOGRAPHY ......................................................................................... 132 SOFTWARE USED .......................................................................................... 134 6 1. INTRODUCTION Aerodynamics is the science of how air flows around and inside objects. More generally, it can be labeled “Fluid Dynamics” because air is really just a very thin type of fluid. Above slow speeds, the air flow around and through a vehicle begins to have a more pronounced effect on the acceleration, top speed, fuel efficiency and handling. Therefore, to build the most efficient possible race car it is needed to understand and optimize how the air flows around and through the body, its openings and its aerodynamic