Presentation of Flow Field Investigation by PIV on a Full-Scale Car in the Pininfarina Wind Tunnel 2000-01-0870
Particle Image Velocimetry (PIV) is a recent measuring technique, which has been used up to now mainly by University Laboratories in small-scale wind tunnels and by Aeronautical Research Centers in small and large facilities. Its use in full-scale automotive testing is not common. It is not so easy, often rather difficult, due to a number of problems, sometimes of practical nature, sometime caused by technology limitations.
This paper reports the results of some tests, carried out by CIRA (Centro Italiano Ricerche Aerospaziali) in the Pininfarina wind tunnel on a full-scale car, in the frame of the European Thematic Network “PIVNET”. A description of the test set up, of the instrumentation used for these tests, as well as an analysis of the advantages provided by this technique and of its present limitations, are reported.
During the tests, in order to outline the potential of this measuring technique, some specific areas of the car flow field, have been investigated. They include the flow downstream of the front wheels and of the rearview mirror. These areas are of most interest as the flow is rather complex and not so easy to measure with other techniques. In particular, the time-dependent 2D-velocity flow field behind the front wheels was measured, in the two conditions of static and rotating wheels. The same flow fields were measured by using two other techniques (14-hole probe and LDV). The time-averaged velocities and the turbulence intensity are then compared and the results of this comparison are shown in the paper.