The vehicle industry demands more and more accurate measurements in every field of automotive technology, to improve the development process of new models. To achieve this objective particularly in the field of vehicle aerodynamics, the flow simulation techniques have recently been improved in some wind tunnels, by introducing suitable means that are able to reproduce the vehicle-to-road relative motion using moving-ground systems undemeath the car as well as by vehicle wheel rotation units, using so called mini-belts to simulate the moving road under the wheels and to spin the wheels. In this way the flow conditions experienced by a vehicle moving on a road are reproduced in the most realistic way within the wind tunnel. All these means certainly improved the road simulation a lot, however there is a small inconvenience due to the fact that the mini-belts upper surfaces are generally larger than the appropriate tire contact areas. Thus some parts of each mini-belt's surface are exposed to the aerodynamic pressure field acting onto the ground in the vicinity of the adjacent wheel. As all normal forces acting between wheels and road are measured by the wind tunnel balance via these mini-belts, the balance measures an additional force, caused by the aerodynamic pressure acting on the mini-belts' surfaces exposed to the flow, together with the actual vehicle lift, which usually increases the measured lift when the mini-belts are static as well as when they are moving. Therefore all lift values measured on mini-belts, or more generally speaking on pads, which are not properly adapted to the shape of the tire contact area, need to be corrected for the specific lift contribution of the pads themselves, the so called pad correction, to obtain the correct vehicle lift. To determine this pad correction precisely is somewhat difficult, especially in the case of moving mini-belts.
A new semi-empiric pad correction procedure
2003
16 Seiten, 12 Bilder, 12 Quellen
Conference paper
English
A new semi-empiric pad correction procedure
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