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Influence of moving-belt dimensions on vehicle aerodynamic forces
Technical Paper
1997-11-0064
Sector:
Language:
English
Abstract
This paper describes an investigation of the validity of using a
short and narrow moving-belt as a means of facilitating the
simulation of the road surface in a full-scale automotive wind
tunnel. The project was jointly funded by Rover Group Ltd. and by
MIRA.
Three 1:4-scale model vehicles were tested in the MIRA Model
Wind Tunnel with moving-belt widths ranging from 250 percent down
to 60 percent of the model width. The moving-belt length downstream
of the models was then reduced from approximately one model length
down to zero.
The models represented a passenger car, a 4 x 4 vehicle, and an
F.1 racing car. Configuration changes were effected by varying the
rear upper body shape, the underbody roughness and profile, the
engine cooling airflow and the ride heights. Measurements were made
of the drag and lift forces acting on the body of each model, and
the drag of the wheels was measured separately.
Broadly, the results showed that both narrowing and shortening
of the belt gave reductions in the model drag forces and increases
in their lift forces (or reductions in down force where the lift
was negative). The magnitude of these changes in forces was
significant, especially in the case of the maximum reduction in
belt size, and there was a degree of model configuration
dependence.
It is therefore concluded that reducing the width of a
moving-belt to allow it to run between the wheels of a car and
shortening its length to fit within a typical balance turntable
would significantly detract from the simulation of road conditions
obtained with a "full-size"" moving belt.