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The Optimization of Roof Trailing Edge Geometry of a Simple Square-Back.
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 12, 2010 by SAE International in United States
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A large contribution to the aerodynamic drag of a vehicle is the loss of pressure in the wake region, especially on square-back configurations. Wake pressure recovery can be achieved by a variety of physical shape changes, but with vehicle shapes becoming ever more aerodynamically efficient research into active technologies for flow manipulation is becoming more prominent. The aim of the current paper is to generate an understanding of how an optimized roof trailing edge, in the form of a chamfer, can reduce wake size, increase base pressures and reduce drag.
A comprehensive study using PIV (Particle Image Velocimetry), balance measurements and static pressure measurements was performed in order to investigate the flow and wake structure behind a simplified car model. Significant reductions in C d are demonstrated and directly related to the measured base and slant pressures. The PIV data shows both the time averaged structure of the wake and the unsteady shedding associated with the upper separation.
The work is intended to act as a precursor for quantifying the effectiveness of active technologies such as Synthetic Jets which aim to achieve the same goals as this passive optimization, but require an energy input.
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CitationLittlewood, R. and Passmore, M., "The Optimization of Roof Trailing Edge Geometry of a Simple Square-Back.," SAE Technical Paper 2010-01-0510, 2010, https://doi.org/10.4271/2010-01-0510.
- Burest G.P. Fedeli R.B. Ferraresi A. “Influence of afterbody rounding on the pressure drag of an axisymmetrical bluff body” Journal of Wind Engineering and Industrial Aerodynamics 69-71 1997 179 188
- Ahmed S.R. Ramm G. Faltin G. “Some Salient Features Of The Time-Averaged Ground Vehicle Wake,” SAE Technical Paper 840300 1984
- Howell J. Le Good., G “The Effect of Backlight Aspect Ratio on Vortex and Base Drag for a Simple Car-Like Shape,” SAE Technical Paper 2008-01-0737 2008
- Wong D.T. Mair W.A. “Boat-Tailed Afterbodies of Square Section as Drag Reduction Devices” Journal of Wind Engineering and Industrial Aerodynamics 12 1983 229 235
- Lanser W.R. Ross J.C. Kaufman, A.E. “Aerodynamic Performance of a Drag Reduction Device on a Full-Scale Tractor/Trailer,” SAE Technical Paper 912125 1991
- Beaudoin J-F. Aider J-L. “Drag and lift reduction of a 3D bluff body using flaps” Exp Fluids 2008 44 491 501
- Howell J. Sheppard A. Blakemore, A. “Aerodynamic Drag Reduction for a Simple Bluff Body Using Base Bleed,” SAE Technical Paper 2003-01-0995 2003
- Roumeas M. “Contribution a L'analyse et au Controle des Sillages de Corps Pais rar Aspiration ou Soufflage Continu” L'institut National Polytechnique de Toulouse
- Rouméas M. Gilliéron P. Kourta A. “Analyze and Control of the Near-Wake Flow over a Square Back Geometry” AIAA Paper 2006-3336
- Leclerc C. Levallois E. “Aerodynamic Drag Reduction by Synthetic Jet: A 2D Numerical Study Around a Simplified Car” AIAA Paper 2006-3337
- Hollis D. “Partical Image Velocimetry in Gas Turbine Combustor Flow Fields” 2004 Loughborough University
- Keane R. Adrian R.J. “Optimisation of Partical Image Velocimetrs Part I: Double Pulse Systems” Measurements Science and Technology 1 1202 1215 1990
- Ahmed S.R. Baumert, W. “The Structure of Wake Flow Behind Road Vehicles”
- Bearman P.W. Morel T. “Effect of Free Stream Turbulence on Flow Around Bluff Bodies” Prog. Aerospace Science 20 1983
- Khalighi B. Zhang S. Koromilas C. Balkanyi, S.R. Bernal, L.P. Iaccarino, G. Moin, P. “Experimental and Computational Study of Unsteady Wake Flow Behind a Bluff Body with a Drag Reduction Device” SAE Technical Paper 2001-01-1042 2001
- Mason W.T. Beebe P.S. “The Drag Related Flow Field Characteristics of Trucks and Buses” Aerodynamic Drag Mechanisms of Bluff bodies and Road Vehicles
- Ching W-K. Ng M.K. “Markov Chains; Models, Algorithms and Applications” Springer Series Books