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Design rules for small low speed wind tunnels

Published online by Cambridge University Press:  04 July 2016

R.D. Mehta  and
P. Bradshaw
R.D. Mehta
Affiliation:
Department of Aeronautics, Imperial College of Science and Technology, London
P. Bradshaw
Affiliation:
Department of Aeronautics, Imperial College of Science and Technology, London
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Extract

Even with today’s computers, a wind tunnel is an essential tool in engineering, both for model tests and basic research. Since the 1930s, when the strong effect of free-stream turbulence on shear layers became apparent, emphasis has been laid on wind tunnels with low levels of turbulence and unsteadiness. Consequently most high performance wind tunnels were designed as closed-circuit types (Fig. 1(a)) to ensure a controlled return flow. However, as will be seen below, it is possible with care to achieve high performance from an open-circuit tunnel, thus saving space and construction cost. ‘Blower’ tunnels (with the fan at entry to the tunnel, Fig. 1(b)) facilitate large changes in working section arrangements; to cope with the resulting large changes in operating conditions, a centrifugal fan is preferable to an axial one. For ease of changing working sections the exit diffuser is often omitted from small blower tunnels, at the cost of a power factor greater than unity. This paper concentrates on the design of small blower tunnels but most of the information is applicable to wind tunnels in general.

Type
Technical Notes
Information
The Aeronautical Journal , Volume 83 , Issue 827 , November 1979 , pp. 443 - 453
Copyright
Copyright © Royal Aeronautical Society 1979 

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