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Further Investigations on Gradient Effects
Technical Paper
2004-01-0670
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
In automotive wind tunnels with modern road simulation installations boundary layer pre-suction is a widely-used technique for boundary layer control. The consequence of boundary layer pre-suction is an additional pressure gradient in front of the model. In order to investigate the effects of the additional pressure gradient on drag, experiments were conducted with two different models (scale 1:5) in the IVK Model Wind Tunnel. In these experiments the suction velocity of the boundary layer pre-suction served as a parameter to change the static pressure gradient along the test section and was for this purpose adjusted higher and lower than the standard suction velocity. It is shown that the total drag increment due to boundary layer pre-suction consists of at least two parts: the ground simulation increment and the static pressure gradient increment. The ground simulation increment is due to a decrease in the boundary layer thickness and the resulting modified flow beneath the model. The static pressure gradient increment is due to the unintended additional pressure gradient. Furthermore a method is described to separate both increments and a correction method is proposed to correct the additional gradient effect.
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Authors
- Jochen Wiedemann - Institute of Internal Combustion Engines and Automotive Engineering, University of Stuttgart (IVK) Research Institute of Automotive Engineering and Vehicle Engines, Stuttgart (FKFS)
- Oliver Fischer - Institute of Internal Combustion Engines and Automotive Engineering, University of Stuttgart (IVK) Research Institute of Automotive Engineering and Vehicle Engines, Stuttgart (FKFS)
- Pang Jiabin
Citation
Wiedemann, J., Fischer, O., and Jiabin, P., "Further Investigations on Gradient Effects," SAE Technical Paper 2004-01-0670, 2004, https://doi.org/10.4271/2004-01-0670.Also In
SAE 2004 Transactions Journal of Passenger Cars: Mechanical Systems
Number: V113-6; Published: 2005-07-05
Number: V113-6; Published: 2005-07-05
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