Cogotti, A., "Ground Effect Simulation for Full-Scale Cars in the Pininfarina Wind Tunnel," SAE Technical Paper 950996, 1995, doi:10.4271/950996.
The paper refers to a research program which is presently in progress at Pininfarina. It deals with a new ground effect simulation system for full-scale car testing in an automotive wind tunnel.This research program is carried out in the framework of the “Progetto Finalizzato Trasporti 2” of the Italian C.N.R.The first part of the paper makes an analysis of: The various ground effect simulation systems already existing in the world. The results which can be achieved using these systems. Their main limitations and drawbacks and some considerations about the possibility of using these systems for routine aerodynamic development work on full-scale vehicles. The second part of the paper describes the new Ground Effect Simulation System (GESS) which is presently in operation in the wind tunnel of the Pininfarina Aerodynamic and Aeroacoustic Research Center.Its layout is quite different from the ground effect simulation systems existing in other full-scale automotive wind tunnels. It includes several subsystems, that is to say: A Moving Belt (MB) “between the wheels” integrated in the balance-turntable system. A Tangential Blowing System (TBS) in front of the MB. Two Basic Suction Systems (BSS), one immediately in front of the TBS and the second between the TBS and the MB. A System for Rotating the car Wheels (RWS) through four rollers integrated in the balance pads. A System for Lifting a car (LS) through the wheels and/or the rockers. Also the LS is integrated in the balance pads. The new Pininfarina GESS is therefore more complex than the existing systems, however, it gives several advantages, in particular: The relative car-to-ground motion is well reproduced along the most important part of the car, that is to say under the full length of the car. In general the overall system is much easier to use than the most of the existing full-scale ground simulation systems. Only minor preparation of the car is necessary, in order to conduct tests with a full simulation of the ground motion and wheel rotation. The third part of the paper reports some preliminary results measured on a full-scale car in various conditions with fixed ground/fixed wheels, rotating wheels only, moving ground only and moving ground/rotating wheels.Although these values are likely to be “car-dependent”, they give a first indication of the possible differences which can be expected when using the new Ground Effect Simulation System.