CFD Investigations of Wind Tunnel Interference Effects 2007-01-1045
Wind tunnel interference effects are still considered to be negligible - or at least undesired - in automotive aerodynamics. Consequently, up to now there is no standard correction method which is used in everyday wind tunnel testing although a lot of research has been done in recent years.
In most full-vehicle CFD simulations, wind tunnel interference effects are not simulated. The flow about the car is computed under idealized conditions. The wind tunnel is designed to simulate these conditions but fails to do so to some degree due to its limited size.
Therefore a comparison of blockage-free CFD results and wind tunnel measurements is deficient. Hence CFD simulations including wind tunnel interference effects should be favored in the future for validation purposes. Furthermore, CFD offers new possibilities to investigate individual contributions to wind tunnel interference effects and therefore could help to increase the understanding of the flow in the wind tunnel. This may result in the development of advanced correction methods. To be able to use these possibilities, it has to be ensured that all effects of the whole wind tunnel test section with a car present will be captured in a simulation.
In this paper simulations of the IVK model scale wind tunnel including wind tunnel interference effects are presented. As a first parameter variation, the influence of different longitudinal pressure distributions in the virtual test section are investigated and compared with test data. This investigation is presented here. In a second step, different vehicle models will be tested. All simulations were carried out with EXA PowerFLOW™.