Car-Wake Imaging Using a Seven-Hole Probe 860214

This paper illustrates an advanced technique recently introduced in the Pininfarina wind tunnel for surveying the flow field of full-scale passenger cars.
The technique is based upon the use of a non-nulling seven-hole probe, which is traversed continuously by a fast traversing system. The traversing system moves in the flow field under computer control.
Planar surfaces of various preselected sizes can be surveyed with corresponding wind tunnel run times ranging from 5 to 40 minutes. As a result of a single planar survey, local pressures and velocities are mapped on a computer colour-display output.
Usually, four colour maps are generated to show and summarize the distribution of total and static-pressure coefficients and total and cross-flow velocities.
This technique is used mainly to investigate body wakes.
Several examples regarding passenger cars or models, as well as an isolated formula-one type rear wing, are reported.
Information provided by this technique, as well as its limitations, are shown.
Interesting information is also obtained when the same technique is employed in flow fields other than the wake of a body.
As an example, maps of pressures and velocities measured in front of various bodies are reported.


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