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Intermittency measurements in the turbulent boundary layer

Published online by Cambridge University Press:  28 March 2006

H. Fiedler  and
M. R. Head
H. Fiedler
Affiliation:
Engineering Department, University of Cambridge
M. R. Head
Affiliation:
Engineering Department, University of Cambridge
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Abstract

An improved version of Corrsin & Kistler's method has been used to measure intermittency in favourable and adverse pressure gradients, and the characteristic parameters of the intermittency have been related to the form parameter H of the mean velocity profiles.

It is found that with adverse pressure gradients the centre of intermittency moves outward from the surface while the width of the intermittent zone decreases. The converse is true of favourable pressure gradients, and it seems likely that at sufficiently low values of H the flow over the full depth of the layer is only intermittently turbulent.

A new method of intermittency measurement is presented which makes use of a photo-electric probe. Smoke is introduced into the boundary layer and illuminated by a narrow beam of parallel light normal to the surface. The photoelectric probe is focused on the illuminated region and a signal is generated when smoke passes through the focal point of the probe lens. Comparison of this signal with the output from a hot-wire at very nearly the same point shows the identity of smoke and turbulence distributions.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 25 , Issue 4 , August 1966 , pp. 719 - 735
Copyright
© 1966 Cambridge University Press

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