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Comments on Some Recent Calculations Relating to the Laminar Boundary Layer with Discontinuously Distributed Suction

Published online by Cambridge University Press:  28 July 2016

W. S. Coleman
W. S. Coleman*
Affiliation:
Blackburn and General Aircraft Ltd.
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Extract

In References (1), (2), Dr. Lachmann develops a method for calculating the growth of the laminar boundary layer over an aerofoil surface with spanwise suction slots placed at intervals along the chord. For this form of control, the laminar flow develops normally from the downstream edge of a slot until it attains the critical Reynolds number (expressed in terms of either the displacement or momentum thickness) at which transition is imminent. The layer then encounters another slot which so thins and stabilises the part not removed by suction, that it is able to continue downstream in the laminar state.

A new feature of the above investigation is the establishment of a second critical Reynolds number which provides an initial condition on the downstream side of a slot. Essentially it defines the minimum value of the displacement or momentum thickness for which, in relation to the local surface roughness, there is no danger of transition due to this form of disturbance.

Type
Technical Notes
Information
The Aeronautical Journal , Volume 61 , Issue 557 , May 1957 , pp. 359 - 361
Copyright
Copyright © Royal Aeronautical Society 1957

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References

1. Lachmann, G. V. (1954). Laminarization through Boundary Layer Control. Aeronautical Engineering Review, Vol. 13, No. 8, 37–51, 1954.Google Scholar
2. Lachmann, G. V. (1955). Boundary Layer Control. Journal of the Royal Aeronautical Society, Vol. 59, No. 531, 163–198, 1955.CrossRefGoogle Scholar
3. Howarth, L. (1938). On the Solution of the Laminar Boundary Layer Equations. Proceedings of the Royal Society, A 164, 547–579, 1938.Google Scholar
4. Schubauer, G. B. (1935). Air Flow in a Separating Laminar Boundary Layer. N.A.C.A. Report No. 527, 1935.Google Scholar
5. Von Doenhoff, A. E. (1940). Investigation of the Boundary Layer about a Symmetrical Airfoil in a Wind Tunnel of Low Turbulence. N.A.C.A. Report No. L-507, 1940.Google Scholar
6. Thwaites, B. (1949). Approximate Calculation of the Laminar Boundary Layer. The Aeronautical Quarterly, Vol. 1, 245–280, 1949.Google Scholar