Aeroacoustics of road vehicles is becoming more and more important as it directly affects the comfort of the passengers.
The tests made in the wind tunnel, in low-turbulence flow conditions, show results that are qualitatively different from those measured on the road.
To get a better understanding of this, Audi and Pininfarina decided to carry out a test campaign on some cars, both on the road and in the wind tunnel, in various turbulent flow conditions.
In the case of road measurements, some typical turbulent flow conditions, like those caused by atmospheric wind and those produced by the traffic, have been investigated.
Wind tunnel measurements have been performed both in the base wind tunnel (in Audi and in Pininfarina) and in the presence of turbulent flows generated, in the Pininfarina wind tunnel, by the Turbulence Generator System, already described in previous SAE papers [1,3,5,7].
The turbulence of the flow that affects the cars was measured, both in the wind tunnel and on the road, by two Cobra probes, while the internal noise of the car was measured by artificial heads, Cortex or Head Acoustics. The results are described in detail in the paper and show that some turbulence and noise conditions measured on the road are similar to those reproduced in the wind tunnel by the TGS. Moreover, a first subjective analysis of the noise measured on the road has been made. Some preliminary results are reported in the paper.