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Spatial variations of the boundary layer in a large low-speed wind tunnel

Published online by Cambridge University Press:  04 July 2016

L. F. East*
Affiliation:
Royal Aircraft Establishment, Farnborough

Extract

In several recent reports reference is made to spanwise variations in the boundary layers growing in the working sections of various wind tunnels. Systematic investigations by Patel, Bradshaw and de Bray are in general agreement that these variations are caused by the screens which are fitted into the settling chambers of these tunnels to dampen out non-uniformities in the upstream flow. They conclude from their experiments that these variations will be much reduced if the downstream screen (or preferably the two downstream screens) has an open area ratio greater than about 0·57 and that these should be followed by a honeycomb to obtain the most steady and uniform flow, although a honeycomb in this position may increase the turbulence level in the working section.

Type
Technical notes
Copyright
Copyright © Royal Aeronautical Society 1972 

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References

1. Head, M. R. and Rechenberg, I. The Preston tube as a means of measuring skin friction. ARC 23, 459, 1962.Google Scholar
2. Fernholz, H. Three-dimensional disturbances in a two-dimensional incompressible turbulent boundary layer. ARC R & M 3368, 1964.Google Scholar
3. Patel, R. P. Effect of wind tunnel screens and honeycomb on the spanwise variation of skin friction in two-dimensional turbulent boundary layers. Canada McGill University, TN 64-7, 1964.Google Scholar
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5. de Bray, B. G. Some investigations into the spanwise non-uniformity of nominally two-dimensional incompressible boundary layers downstream of gauze screens. ARC 29, 271 R & M 3578, 1967.Google Scholar