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A pressure instrument to measure skin friction in turbulent boundary layers on smooth and non-smooth walls

Published online by Cambridge University Press:  04 July 2016

P.V. Storm  and
B.G. Newman
P.V. Storm
Affiliation:
Department of Mechanical Engineering, McGill University, Montreal, Quebec, Canada
B.G. Newman
Affiliation:
Department of Mechanical Engineering, McGill University, Montreal, Quebec, Canada
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Summary

A pressure instrument has been designed for the measurement of local skin friction in turbulent boundary layers on smooth and non-smooth walls. The instrument consists of three pitot tubes placed in the logarithmic mean velocity region of a turbulent boundary layer.

An instrument was built and tested in the boundary layer produced on both smooth and rough walls. The rough walls consisted of two sandpaper abrasives of sizes #40 and #24. The experiments were performed over a range of momentum thickness Reynolds numbers, Rθ, from about 5 × 103 to 18 × 103, and in a small favourable pressure gradient given by –0·0005 < (υ/ρU3τ)(dp/dx) <–0·0001. The non-dimensional equivalent sand roughness, ks+ ≡ ksUτ/υ varied from zero to approximately 85, thus spanning all three roughness regimes from smooth to fully rough. Skin friction coefficients calculated using the three tube instrument were compared to those obtained using a skin friction balance. For the smooth wall measurements, skin friction relations and Preston tubes were also used as a basis of comparison. The results were found to agree fairly well for both the smooth and non-smooth walls, and was independent of the instrument's position within the logarithmic region. However, due to measurement difficulties the scatter and uncertainty were larger for the three tube instrument than the other techniques.

Numerical smoothing of the results indicated that the agreement is expected to improve with better measurement of the pressure differences between the pitot tubes, or direct measurement of the velocity differences.

Type
Research Article
Information
The Aeronautical Journal , Volume 97 , Issue 961 , January 1993 , pp. 25 - 32
Copyright
Copyright © Royal Aeronautical Society 1993 

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References

1. Preston, J.H. The determination of turbulent skin friction by means of pitot tubes,. J Royal Acro Soc, 1954, 58, pp 109–121.Google Scholar
2. Schlichting, H. Boundary layer Theory, McGraw-Hill, 5th edition, New York, 1968.Google Scholar
3. Perry, A.E., Schofield, W.H. and Joubert, P.N. Rough wall turbulent boundary layers,. J Fluid Mech, 1969, 37, pp 383–413.Google Scholar
4. Rotta, J.C. Turbulent boundary layers in incompressible flow, Prog Aeronaut Sri, 1962, 2, pp 1–219.Google Scholar
5. Patel, V.C. Calibration of the Preston tube and limitations on its use in pressure gradients, J Fluid Mech, 1965, 23, pp 185–208.Google Scholar
6. Wygnanski, I. and Newman, B.G. General Description and Calibration of the McGill 3 ft x 2 ft Wind Tunnel, Internal Report Ae4, Mechanical Engineering Department, McGill University, 1961.Google Scholar
7. Townsend, A.A. The response of a turbulent boundary layer to abrupt changes in surface conditions, J Fluid Mech, 1965,22, pp 794–822.Google Scholar
8. Nguyen, V.D., Dickinson, J., Jean, Y., Chalifour, Y., Anderson, J., Lemay, J., Haeberle, D. and Larose, G. Some experimental observations of the law of the wall behind large eddy breakup devices using servo-controlled skin friction balances, Proceedings of AIAA, 22nd Aerospace Sciences Meeting, AIAA-84-0346, 1984.Google Scholar
9. Young, A.D. Boundary Layers, Blackwell Scientific Publications, Oxford, 1989.Google Scholar
10. Von Karman, Th. Turbulence and skin friction, J Aeronaut Sci, 1934, 1, pp 1–20.Google Scholar
11. Ludwieg, H. and Tillmann, W. Investigations of the wall-shearing stress in turbulent boundary layers, NACA TM-1285, 1950.Google Scholar
12. Davies, P.O.A.L. The behaviour of a pitot tube in transverse shear, J Fluid Mech, 1958, 3, pp 441–456.Google Scholar
13. Young, A.D. and Maas, J.N. The Behaviour of a Pitot Tube in a Transverse Pressure Gradient, Aeronautics Research Council R & M 1770, 1937.Google Scholar
14. Macmillan, F.A. Experiments on Pitot Tubes in Shear Flow, Aeronautics Research Council R & M 3028, 1956.Google Scholar
15. Livesey, J.L. The behaviour of transverse cylindrical and forward-facing total head probes in transverse total pressure gradients, J Aeronaut Sci, 1956, 23, pp 949–955.Google Scholar
16. Macmillan, F.A. Viscous effects on pitot tubes at low speeds, J Royal Aero Soc, 1954, 58, pp 570–572.Google Scholar
17. Ower, E. and Pankhurst, R.C. The Measurement of Air Flow, Pergamon Press, 5th edition, Oxford, 1977.Google Scholar
18. Moffat, R.J. Describing the uncertainties in experimental results, Exp Therm Fluid Sci, 1988, 1, pp 3.Google Scholar