Simulation of Transient Phenomena with the Turbulence Generation System in the Pininfarina Wind Tunnel

It is shown that it is possible to measure some aspects of transient phenomena of either passenger or sports cars, by the use of the Turbulence Generation System (TGS) installed in the Pininfarina Wind Tunnel. In order to better assess the aerodynamic performance of the vehicle and its consequences in terms of stability and safety, the behaviour of a generic car under the influence of an unstationary flow has to be carefully measured and evaluated.

Both time averaged and time dependent analysis of the aerodynamic coefficients are shown in the case of:

1. 1a.
   Simulation of continuous yawing of the oncoming flow;
2. 1b.
   Simulation of an impulsive change of the yaw of the oncoming flow;
3. 2.
   Simulation of the first phase of an overtaking manoeuvre.

An update on the results shown in the SAE paper 2005-01-1455, is given with particular emphasis on the quantity ∂ C_LF/∂ V or proposed as the key parameter to quantify the change of front lift of a specific car in the presence of a generic upstream vehicle.