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The Shape-Factor Relationship for Turbulent Boundary Layers

Published online by Cambridge University Press:  07 June 2016

M.M.M. El Telbany ,
J. Niknejad  and
A.J. Reynolds
M.M.M. El Telbany*
Affiliation:
Department of Mechanical Engineering, Brunel University, Uxbridge, Middlesex
J. Niknejad
Affiliation:
Department of Mechanical Engineering, Brunel University, Uxbridge, Middlesex
A.J. Reynolds
Affiliation:
Department of Mechanical Engineering, Brunel University, Uxbridge, Middlesex
*
*Permanent address: Faculty of Engineering, Helwan University, Elmataria, Cairo, Egypt.
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Summary

Consideration is given to the relationship H1 = f(H) linking the common shape factor H and the mass-flow shape parameter H1 which is used in entrainment models of boundary-layer development. A formula suggested by Green et al is found to be most nearly consistent with the measurements presented. However, a more exact prediction of H1 is obtained by introducing a factor involving the Reynolds number based on the local momentum thickness θ; thus H1 = f(H, Reθ). Predictions obtained by incorporating the appropriately modified entrainment equation into the well-known method of Green et al prove not to give an improved representation of the development of boundary layers studied experimentally by the authors and others. It is concluded that the modified formula for H1 is primarily useful in giving an improved specification of the overall boundary layer thickness δ = θ(H1 + H), and hence of other features of the developing profile.

Type
Research Article
Information
Aeronautical Quarterly , Volume 34 , Issue 2 , May 1983 , pp. 147 - 161
Copyright
Copyright © Royal Aeronautical Society. 1983

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References

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