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Comparison of Impact Due to an Aerodynamic Component in Wind Tunnel and On-Road Tests
Technical Paper
2011-01-0157
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
The aerodynamic performance of new vehicles is commonly determined using computational fluid dynamics (CFD) and wind tunnel tests. The final assessment is carried out by actual running tests. In particular, ideas regarding fuel consumption improvement that relate to components for the reduction of the coefficient of drag (CD) value are evaluated by coast-down tests. However, a difference often exists between the component's efficiency between wind tunnel tests and coast-down tests. Therefore, we focused on the efficiency of an air-dam spoiler in reducing CD values. A comparison was made between the aerodynamic effect of the air-dam spoiler in wind tunnel and coast-down tests in terms of the CD value and the wake structure behind the vehicle. To determine the relationship between the CD value and the wake structure behind the vehicle, we measured vehicle speed, wind velocity and direction, vehicle height, and pressure distribution on the back door. The results revealed that the CD values were reduced approximately 7% by attaching the air-dam spoiler in both the wind tunnel and coast-down tests. In contrast, the values of pressure coefficient restoration on the back door differed between the wind tunnel and coast-down tests. In the coast-down tests, the values of pressure coefficient restoration were approximately 16% less than those in the wind tunnel tests. Similarly, the Strouhal numbers of the pressure coefficient of the coast-down tests were smaller than those of the wind tunnel tests. This was considered to be causally related to the rolling wheels and the moving ground under the vehicle in the actual running tests. Given this, we should study the flow field behind the vehicle to elucidate the relationship between the CD value and the wake structure. This correlation also needs to be examined in terms of the pressure measurement results.
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Katoh, D., Hashizume, Y., Kohri, I., and Takagi, M., "Comparison of Impact Due to an Aerodynamic Component in Wind Tunnel and On-Road Tests," SAE Technical Paper 2011-01-0157, 2011, https://doi.org/10.4271/2011-01-0157.Also In
References
- Le Good, G.M Howell, J.P. Passmore, M.A. Garry, K.P. “On-Road Aerodynamic Drag Measurements Compared with Wind Tunnel Data,” SAE Technical Paper 950627 1995 10.4271/950627
- Le Good, G.M Howell, J.P. Passmore, M.A. Cogotti, A. “A Comparison of On-Road Aerodynamic Drag Measurements with Wind Tunnel Data from Pininfarina and MIRA,” SAE Technical Paper 980394 1998 10.4271/980394
- Howell, J. Sherwin, C. Passmore, M. Le Good, G. “Aerodynamic Drag of a Compact SUV as Measured On-Road and in the Wind Tunnel,” SAE Technical Paper 2002-01-0529 2002 10.4271/2002-01-0529
- Lawson, A.A. Dominy, R.G. Sheppard, A. “A Comparison of On-Track and Wind Tunnel Surface Pressure Measurements on a Compact SUV,” SAE Technical Paper 2003-01-0653 2003 10.4271/2003-01-0653
- Lawson, A.A. Dominy, R.G. Sims-Williams, D.B. Mears, P. “A Comparison Between On-Road and Wind Tunnel Surface Pressure Measurements on a Mid-Sized Hatchback,” SAE Technical Paper 2007-01-0898 2007 10.4271/2007-01-0898
- Hashizume, Y. Kato, D. “Pressure Distribution on Back-door with/without Air-dam Skirt by Wind-tunnel,” JSAE Symposium Text 20104179 2010
- Kuenstner, R. Deutenbach, K.-R. Vagt, J.-D. “Measurement of Reference Dynamic Pressure in Open-Jet Automotive Wind Tunnels,” SAE Technical Paper 920344 1992 10.4271/920344
- Mercker, E. Wickern, G. Weideman, J. “Contemplation of Nozzle Blockage in Open Jet Wind-Tunnels in View of Different ‘Q’ Determination Techniques,” SAE Technical Paper 970136 1997 10.4271/970136
- Takagi, H. “An Extraction Method of Real-life Drag Coefficient from Coast Down Test by Incorporating the Effect of Natural Wind in the Analysis Algorithm,” JSAE Symposium Text 20084221 2008
- Hirokawa, T. Takagi, M. “Development of Three-Hole Velocimeter,” JSAE Symposium Text 20084219 2008
- Haijima, H. Takagi, M. “Unsteady Pressure Fields around a Passenger Car Model,” 11 th International Symposium on Flow Visualization 2004
- Yang, H. Sims-Williams, D. B. He, L. “Unsteady Measurement with Correction on Tubing Distortion,” International Symposium on Unsteady Aerodynamics, Aeroacoustics and Aeroelasticity in Turbomachines 10 1-4020-4267-1 521 529 2003
- Landström, C. Löfdahl, L. Walker, T. “Detailed Flow Studies in Close Proximity of Rotating Wheels on a Passenger Car,” SAE Int. J. Passeng. Cars - Mech. Syst. 2 1 861 874 2009 10.4271/2009-01-0778
- Okada, Y. Nouzawa, T. Nakamura, T. Okamoto, S. “Flow Structures above the Trunk Deck of Sedan-Type Vehicles and Their Influence on High-Speed Vehicle Stability 1st Report: On-Road and Wind-Tunnel Studies on Unsteady Flow Characteristics that Stabilize Vehicle Behavior,” SAE Int. J. passing. Cars - Mech. Syst. 2 1 138 156 2009 10.4271/2009-01-0004