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Thick, two-dimensional wake roll-up behind a wing of finite span—extended calculations

Published online by Cambridge University Press:  04 July 2016

H. Portnoy
H. Portnoy*
Affiliation:
Department of Aeronautical Engineering, Technion-lsrael Institute of Technology, Haifa
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Extract

Reference 1 describes a numerical procedure for calculating the roll-up of the wake behind a wing of finite span, when the wake vorticity is assumed to occur within a layer of finite thickness with thin elliptic cross-section normal to the stream. The vorticity is assumed to be a function of spanwise position only (corresponding to a linear transverse velocity profile when the wake is thin), the process is treated as a two-dimensional unsteady one, as in the work of Westwater, Moore and others, and viscous and turbulence effects are ignored.

In Ref. 1 the technique was applied to the classical elliptic loading, to calculate the very early stages of the roll-up. In the present paper these calculations are extended to larger values of the dimensionless time t* and the results are seen to tally fairly well with those of Moore, which were obtained by using a point-vortex model. Similar calculations have also been carried out for a particular non-elliptic loading which was dealt with by Clements and Maull by a two-dimensional, point-vortex method. They gave this loading as an example of a distribution which produces two roll-up cores on each half span, with an induced drag only 10% greater than that of the elliptic loading having the same Ch. The results of the new calculations are presented here, and are seen to be similar to those of Ref. 4 in a general way, both qualitatively and quantitatively.

Type
Technical note
Information
The Aeronautical Journal , Volume 81 , Issue 802 , October 1977 , pp. 460 - 463
Copyright
Copyright © Royal Aeronautical Society 1977 

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References

1. Portnoy, H. The initial roll-up of a thick, two-dimensional wake behind a wing of finite span. The Aeronautical Journal, Vol 80, No 790, pp 442–447, October 1976.Google Scholar
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