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Developments in wind tunnel testing of road vehicles
Technical Paper
1997-11-0062
Sector:
Language:
English
Abstract
Wind tunnels have been used for at least seventy years for
investigating the aerodynamic characteristics of road vehicles.
This use has intensified markedly, however, since the oil crisis of
1973-4. Full-scale automotive wind tunnels have proliferated, and
small-scale testing has also increased.
Various wind-tunnel designs have been adopted, with open-jet,
closed-jet and slotted-wall test sections and open and
closed-return circuits. Representation of the road surface by the
been employed to improve this representation by minimizing the
tunnel-floor boundary layer effects, and new variations are
currently under development.
Steady cross-wind conditions are usually simulated by setting
the vehicle/model at one or more yaw angles relative to the tunnel
airstream. Additionally, some novel techniques have recently been
developed for simulating cross-wind gusts.
A wide range of test activities is performed in automotive wind
tunnels. Most commonly, aerodynamic forces and pressures are
measured. Flow visualization and velocity surveys are also
frequently performed, for various purposes.
Climatic testing of vehicles is a further major activity in
automotive wind tunnels, with the twin aims of ensuring adequate
cooling of various mechanical components and providing acceptable
passenger comfort in all likely operating conditions. Passenger
comfort is also the objective behind the growing use and
development of aero-acoustic wind tunnels.