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A Note on the Mixing Process in the Flow Induced by a High Velocity Air Jet

Published online by Cambridge University Press:  28 July 2016

J. Black
J. Black*
Affiliation:
Department of Aeronautical Engineering, University of Bristol
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Extract

It is well known that when a plane air jet of high velocity blows over a convex surface, such as the upper surface of a lowered trailing edge flap, it flows along the surface, remaining attached for a considerable length; in the case of the flap, it adheres right to the trailing edge. This effect, usually described as the Coanda effect, has been utilised in the attempts to increase lift at constant incidence by “flap-blowing” in which the high velocity air jet is ejected either through slots in the flap shroud, or tangentially out of the flap surface.

The low velocity air stream approaching the flap over the wing upper surface, which in the absence of “blowing” would tend to separate at the flap shroud, is entrained by the high velocity jet, and the incipient flow separation over the flap thereby suppressed. The energy contained in the “blowing” jet can, in addition, also produce “supercirculation.“

Type
Technical Notes
Information
The Aeronautical Journal , Volume 61 , Issue 561 , September 1957 , pp. 631 - 633
Copyright
Copyright © Royal Aeronautical Society 1957

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References

1. Williams, J. (1954). An Analysis of Data on Blowing over Trailing Edge Flaps for Increasing Lift. A.R.C. Current Paper No. 209, September 1954.Google Scholar
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3. Practical Work on “Flap-Blowing.” de Havilland Gazette. p. 80, No. 93, June 1956.Google Scholar
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7. Eyles, A. J. and Foster, D. N. (1957). An Investigation of the Curved Flow Induced by a High Pressure Jet. University of Bristol, Aeronautical Laboratory Honours Report No. 30, June 1957.Google Scholar