Evaluation of the force coefficients from Chapter 4 shows that the CFD method as presented here operates in a robust manner and, thanks to its high prediction accuracy, is suitable for the vehicle development process. Maximum deviations occur at up to ΔcL,r = 0.050 for rear axle lift. It was clear from both experiment and computation, however, that the flow away from the rear end is extremely transient in character and causes a high degree of scatter in the results. In view of this, the simulation results for rear axle lift can be regarded as sufficiently accurate despite what appear at first glance to be considerable deviations. A further improvement in their conformity would nonetheless be desirable. It has been shown that, thanks to its high prediction quality, the CFD method can be used in Audi¡|s aerodynamic development work for the evaluation of both exterior styling studies and a very wide variety of add-on parts. The range of applications extends from underfloor measures to mirror shapes and detail body modifications. In such cases, information on the influence of aerodynamic drag was obtained to a good standard of accuracy. In the case of changes in lift, the tendency has at least been proved correct. Investigations of the influence of the cooling airflow on the air force coefficients have proved to yield very promising initial results. For the two vehicles that were investigated, the aerodynamic drag value prediction levels were 77.3 % and 91.4 %. Lift coefficient changes due to inclusion of the engine¡|s cooling airflow were also shown. Only the computed value for the influence of cooling air on the Audi Q7¡|s front axle lift proved, at 40.2 %, to be rather too low. Nonetheless, the results can be regarded as a benchmark in motor vehicle aerodynamic development.
CFD validation progress in vehicle aerodynamics development at Audi
2011
18 Seiten, 9 Bilder, 2 Tabellen, 13 Quellen
Conference paper
English
CFD validation progress in vehicle aerodynamics development at Audi
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