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Experimental Investigation of Unsteady Vehicle Aerodynamics under Time-Dependent Flow Conditions - Part 1
Technical Paper
2011-01-0177
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
Unsteady aerodynamic flow phenomena are investigated in the wind tunnel by oscillating a realistic 50% scale model around its vertical axis. Thus the model is exposed to time-dependent flow conditions at realistic Reynolds and Strouhal numbers. Using this setup unsteady aerodynamic loads are observed to differ significantly from quasi-steady loads. In particular, the unsteady yaw moment exceeds the quasi-steady approximation by 80%. On the other hand, side force and roll moment are over predicted by quasi-steady approximation but exhibit a significant time delay. Using hotwire anemometry, a delayed reaction of the wake flow of Δt/T = 0.15 is observed, which is thought to be the principal cause for the differences between unsteady and quasi-steady aerodynamic loads. A schematic mechanism explaining these differences due to the delayed reaction of the wake flow is proposed. Additionally, the wake topology observed in previous studies for constant yaw featuring fluid entering into the wake region from the leeward side accompanied by two counter-rotating vortices is confirmed.
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Citation
Theissen, P., Wojciak, J., Heuler, K., Demuth, R. et al., "Experimental Investigation of Unsteady Vehicle Aerodynamics under Time-Dependent Flow Conditions - Part 1," SAE Technical Paper 2011-01-0177, 2011, https://doi.org/10.4271/2011-01-0177.Also In
References
- Wordley, S. Saunders, J. “On-road Turbulence,” SAE Int. J. Passeng. Cars - Mech. Syst. 1 1 341 360 2008 10.4271/2008-01-0475
- Wordley, S. Saunders, J. “On-road Turbulence: Part 2,” SAE Technical Paper 2009-01-0002 2009 10.4271/2009-01-0002
- Wojciak, J. Theissen, P. Indinger, T. Adams, N.A. Demuth, R. “Experimental Study of On-Road Aerodynamics during Crosswind Gusts” MIRA International Vehicle Aerodynamics Conference UK October 13 14 2010
- Tsubokura, M. Nakashima, T. Kitoh, K. Sasaki, Y. “Development of unsteady aerodynamic simulator using large-eddy simulation” 7th FKFS Conference Germany October 6 7 2009
- Tsubokura, M. Nakashima, T. “Unsteady Aerodynamic Simulator for Road Vehicles based on Large-Eddy Simulation” MIRA International Vehicle Aerodynamics Conference UK October 13 14 2010
- Favre, T. Efraimson, G. “Numerical Study of Design Alterations Affecting the Crosswind Characteristics of a Generic Road Vehicle Model” MIRA International Vehicle Aerodynamics Conference UK October 13 14 2010
- Theissen, P. Demuth, R. Adams, N.A. “Unsteady phenomena in vehicle aerodynamic under time-dependent flow conditions” 10th Stuttgart International Symposium Germany March 16 17 2010
- Theissen, P. Wojciak, J. Demuth, R. Indinger, T. Adams, N.A. “Unsteady Aerodynamic Phenomena under Time-Dependent Flow Conditions for Different Vehicle Shapes” MIRA International Vehicle Aerodynamics Conference UK October 13 14 2010
- Gohlke, M. Beaudoin, J.F. Amielh, M. Anselmet, F. “Experimental analysis of flow structures and forces on a 3D-bluff-body in constant cross-wind” Experiments in Fluids 43 579 594 2007
- Lemke, T. “Untersuchung der Fahrzeugumströmung bei Seitenwind für die Frühphase der PKW-Entwicklung” PhD Thesis Universität Siegen 2006
- Guilmineau, E. Chometon, F. “Numerical and Experimental Analysis of Unsteady Separated Flow behind an Oscillating Car Model,” SAE Int. J. Passeng. Cars - Mech. Syst. 1 1 646 657 2008 10.4271/2008-01-0738
- Mullarkey, S.P. “Aerodynamic stability of road vehicles in side winds and gusts” PhD thesis University of London 1990
- Bearman, P.W. Mullarkey, S.P. “Aerodynamic Forces on Road Vehicles due to Steady Side Winds and Gusts” RAeS, Vehicle Aerodynamics Conference Loughborough 1994
- Passmore, M.A. Richardson, S. Imam, A. “An experimental study of unsteady vehicle aerodynamics” Proceedings of the Institution of Mechanical Engineers 215 Journal of Automobile Engineering 2001
- Carlino, G. Cogotti, A. “Simulation of Transient Phenomena with the Turbulence Generation System in the Pininfarina Wind Tunnel,” SAE Technical Paper 2006-01-1031 2006 10.4271/2006-01-1031
- Schröck, D. Widdecke, N. Wiedemann, J. “Aerodynamic Response of a Vehicle Model to Turbulent Wind” 7th FKFS Conference Germany October 6 7 2009
- Garry, K.P. Cooper, K.R. “Comparison of Quasi-Static and Dynamic Wind Tunnel Measurements of Simplified Tractor-Trailer Models” Journal of Wind Engineering and Industrial Aerodynamics 22 1986
- Passmore, M.A. Mansor, S. “The Measurement of Transient Aerodynamics Using an Oscillating Model Facility,” SAE Technical Paper 2006-01-0338 2006 10.4271/2006-01-0338
- Mansor, S. Passmore, M.A. “Estimation of bluff body transient aerodynamics using an oscillating model rig” Journal of Wind Engineering and Industrial Aerodynamics 96 1218 1231 2008
- Watkins, S. Toksoy, S. Saunders, J.W. “On the Generation of Tunnel Turbulence for Road Vehicles” 11 th Australian Fluid Mechanics Conference Australia December 14 18 1992
- Technische Universitaet Muenchen, BMW Group Audi “DrivAer Vehicle - New Generic Vehicle Geometry”
- RUAG Calibration report for DMS-Balance 788-6B 2009
- Kistler Instruments Manual K-Beam Capacitance Acceleration Sensor
- Demuth, R. Buck, P. “Numerical Investigations on the Unsteady Aerodynamics of Road Vehicles under Gusty Weather Conditions” MIRA International Vehicle Aerodynamics Conference UK October 25 26 2006
- Heuler, K. “Analysis of the flow topology in the wake of a notchback vehicle under constant yaw” Diploma Thesis Technische Universitaet Muenchen, Institute of Aerodynamics