THE EFFECT OF GROUND SIMULATION ON THE FLOW AROUND VEHICLES IN WIND-TUNNEL TESTING

Aerodynamic design has become more and more important in the development of modern road and rail vehicles. Therefore, in wind tunnel testing, it is necessary to reproduce the natural conditions on a vehicle as exactly as possible. This paper reports on the effect of ground simulation on vehicle aerodynamics. It is shown that the only accurate simulation technique is the moving ground simulation. The ground effect was investigated with a simple body of two lengths for different ground clearances over a moving belt and a fixed plate. The aerodynamic forces were measured using a six-component balance. For selected parameter configurations, velocities of flow around the body were also obtained. It was found that for small ground clearances especially, the ground simulation has a strong influence on the flow field, resulting in significant effects on the aerodynamic lift and drag.