Update on the Pininfarina “Turbulence Generation System” and its effects on the Car Aerodynamics and Aeroacoustics

The Turbulence Generation System designed and built in Pininfarina in the years 1999-2002, has been in operation since the beginning of 2003. The purpose of this device is to reproduce in the wind tunnel a flow condition more similar to that found by the cars on the road, in terms of velocity profile and turbulence intensity/length scale.

The paper reports an updated description of its mechanical and aerodynamic characteristics.

Then it reports examples of results measured on some cars, in the condition of turbulent flow, regarding:

• Aerodynamics - time averaged and time-dependent aero coefficients.
• Aeroacoustics - auto spectra and psycho acoustic parameters.
• Deformation/vibration of some car body parts (bonnet, doors).

The differences between these results and those measured in standard low-turbulence conditions are presented.

In addition a description of some techniques that are used for these time-dependent measurements is reported.