Experimental Investigation of Unsteady Vehicle Aerodynamics under Time-Dependent Flow Conditions - Part 1 BMW Group

Format:

Conference/Event

Author/Creator:

Theissen, Theissen, author.

Contributor:

Adams, N. (Nikolaus)

Demuth, Rainer

Heuler, Kirstin

Indinger, Thomas

Wojciak, Johannes

Conference Name:

SAE 2011 World Congress & Exhibition (2011-04-12 : Detroit, Michigan, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2011

Summary:

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

Notes:

Vendor supplied data

Publisher Number:

2011-01-0177

Access Restriction:

Restricted for use by site license