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B. E. PROJECT DRAG FORCE ANALYSIS OF CAR PROJECTEES ABHISHEK KUMAR RAVISHEK KUMAR ASHWIN TEMBHURNEY ABHISHEK GOMASE GUIDE Prof. R. M. Metkar SESSION 2005-2006 DEPARTMENT OF MECHANICAL ENGINEERING G. H. RAISONI COLLEGE OF ENGINEERING, NAGPUR.
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B. E. PROJECT DRAG FORCE ANALYSIS OF CAR PROJECTEES ABHISHEK KUMAR RAVISHEK KUMAR ASHWIN TEMBHURNEY ABHISHEK GOMASE GUIDE Prof. R. M. Metkar SESSION 2005-2006 DEPARTMENT OF MECHANICAL ENGINEERING G. H. RAISONI COLLEGE OF ENGINEERING, NAGPUR.
CONTENTS • Introduction • Motivation • Regimes of External Flow • Profile Drag • Minimizing Drag on a LMV • Expression For Drag Force • Stream-lined and Bluff Body • Components of Drag • Thrust Vs Speed of Car • Geometry generation in pro/e wildfire • Analysis in CFD Tutor 1.1 • Calculations and Result • Limitations • Conclusion • References
INTRODUCTION • Decreasing the fuel consumption of road vehicles. • Drag is one of the most important issues when it comes to Aerodynamics design of road vehicles
MOTIVATION • Designing a vehicle with a minimized drag resistance provides economy and performance advantages. • The main motivation for reducing drag resistance is: • Fuel consumption reduction • Performance increasing
REGIMES OF EXTERNAL FLOW FLOW REGIMES AROUND AN IMMERSED BODY
PROFILE DRAG • Pressure drag • Friction drag Profile drag = Pressure drag + Friction drag PRESSURE DRAG AIRFLOW ORIENTATION
Expression For Drag Force • The Drag force value for a moving vehicle is given by the following expression. DF =1/2 A ρ CD V2 where , CD is the drag coefficient A is the projected frontal area of the vehicle ρ is the density of air V is the speed of the vehicle relatively to the air
MINIMIZING DRAG ON A LMV(CAR) SHAPE OF VEHICLE’S BODY
GEOMETRY GENERATION IN PRO/E WILDFIRE DIMENSIONS : OVERALL LENGH 3335 mm OVERALL WIDTH 1440 mm 2D SKETCH OF MARUTI 800
ANALYSIS IN CFD TUTOR 1.1 PRE- PROCESSING IN CFD TUTOR 1.1 Grid Generation for Maruti 800
PROCESSING OPERATIONS IN CFD TUTOR 1.1 Pressure distribution along the body of car
POST PROCESSING OPERATION IN CFD TUTOR 1.1 Pressure Distribution along the shape of car
CALCULATIONS AND RESULT Drag Force, DF = 1/2 A ρ CD V2 ------------------------------ ----I Pressure Drag, P = ∆P * A ------------------------------------------II Equating Equation I and II, we get ∆P * A = 1/2 A ρ CD V2 Therefore, CD = 2 ∆P/ ρ V2 --------------------------------------III For Mach No. = 0.05 (60 Km/hr) Pmax = 1.0669 *105 Pa Pmin = 1.0086* 105 Pa ∆P= 5830 Pa ρ = 1.125 kg/m3 Vmax = 1.246 m3/ s Put the values in equation III, we get CD = 0.667
LIMITATIONS • Space Constraint • Styling may be the most flagrant example: Consumers/buyers always seek for a certain ‘look'. This concept is today very different from the aerodynamically ‘ideal’ car. • Drag and Lift Relation
CONCLUSION • Smooth vehicle shape, rounded corners. • Tapered rear end. • Minimized body seams. • Substitution of rear view mirrors with Cameras. • Smooth underbody.
REFERENCES • Paper: Inchul Kim and Xin Geng, [2002], “Optimization of Body Shape through Computation of Aerodynamic Forces on Low Mass Vehicle (LMV)”, Department Of Mechanical Engineering, University Of Michigan-Dearborn, Dearborn, Mi 48128. • Paper: Alexander Diehl, Jose Nuno Lopes, Rui Miranda, Christoffer Mursu Simu and John Viji, autumn 2002, “Reducing Drag Forces in Future Vehicles”, Department of Thermo and Fluid Dynamics, Chalmers, University of Technology. • Paper: Frederque Muyl, Laurent Dumas and Vincent Herbert, [October 2001], “Hybrid method for Automotive Shape Optimization in Automotive Industry, PSA Peugeot Citroen, Centre technique, Veliz Villacoublay, France • Book: Fluid Mechanics By John F Douglas, Janusz M Gasiorek and John A Swaffield, Published by Pearson Educations. • Websites: www.engin.umd.umich.edu/ceep/tech_day www.maruti800.marutiudyog.com www.princeton.edu/~asmits/Bicycle_web/blunt.html • Project Website: www.dragforceanalysis.tk