2.1 Background of Wind Tunnels
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Fig. 2.1 Vintage cartoon of the Eiffel wind tunnel (© J.-M. Seguin, CSTB Eiffel Laboratory)
directly downstream of the test section. Figure 2.1 is an artistic representation of the
Eiffel Wind Tunnel presently located in Auteuil, in Paris, and operated by the Centre
Scientifique et Technique du Bâtiment (CSTB).
2.1.3 The Prandtl Type or Closed Circuit Wind Tunnel
In this installation, the air, after being sucked downstream of the test section and
the diffuser is guided through four successive corners, and then recirculated again
through the settling chamber (see Fig. 2.2). Turning vanes arranged in the corners
of the circuit ensure that flow separation and the formation of vortices are avoided.
This arrangement leads to improved energy efficiency and allows better control over
the test conditions (pressure, temperature, moisture). This type of installation may
require a heat exchanger in order to cool down the air flow which is being heated
while extracting energy from the fan or compressor to maintain the circulation of the
air flow.
Fig. 2.2 Installation of a
closed circuit wind tunnel