Hostname: page-component-745bb68f8f-mzp66 Total loading time: 0 Render date: 2025-01-12T12:44:15.163Z Has data issue: false hasContentIssue false
  • English
  • Français

Decay of a Viscous Trailing Vortex

Published online by Cambridge University Press:  07 June 2016

D. S. Dosanjh ,
E. P. Gasparek  and
S. Eskinazi
D. S. Dosanjh
Affiliation:
Syracuse University, New York
E. P. Gasparek
Affiliation:
Syracuse University, New York
S. Eskinazi
Affiliation:
Syracuse University, New York
Get access

Summary

An experimental investigation of the viscous decay of a steady, three-dimensional, helical vortex is presented. The vortex was generated by a rectangular, symmetrical half aerofoil (N.A.C.A. 0009) of 10·5 in. span, 3 in. chord, cantilevered from the wall of the circular test section of a low speed wind tunnel. Only the local total head and flow directions were measured with a five-hole pressure sensitive probe at one to eight chord lengths behind the trailing edge of the aerofoil, and the radial, tangential and axial velocity distributions in the trailing vortex were derived. The static pressure variation in the vortex flow and the difficulties in its accurate measurement are discussed. All tests were performed at a Reynolds number based on the free-stream velocity and chord length of the aerofoil of 10,000.

The various experimental velocity distributions in the vortex were in good agreement with a linearised, axi-symmetric, laminar, incompressible, viscous vortex due to Newman. The decay of velocity and geometry parameters, however, were found to be approximately eight to ten times faster than predicted by the analysis based on a laminar kinematic viscosity. It was also observed that the amount of circulation which actually rolled up in the trailing vortex was only about 58 per cent of that expected around the (N.A.C.A. 0009) aerofoil used for this investigation.

Type
Research Article
Information
Aeronautical Quarterly , Volume 13 , Issue 2 , May 1962 , pp. 167 - 188
Copyright
Copyright © Royal Aeronautical Society. 1962

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Taneda, S. Studies of Wake Vortices II. Report of the Research Institute of Applied Mechanics, Kyushu University, Japan, Vol. 1, p. 29, 1955.Google Scholar
2. Timme, A. Uber die Geschwindigkeitsverteilung in Wirblen, Ingenieur Archiv., Vol. XXV, p. 205, 1957.Google Scholar
3. Kovasznay, L. S. G. Hot Wire Investigations of the Wake Behind Cylinders at Low Reynolds Numbers, Proc. Roy Soc. A198, p. 174, 1949.Google Scholar
4. Schaefer, J. W. and Eskinazi, S. An Analysis of the Vortex Street Generated in a Viscous Fluid. Journal of Fluid Mechanics, Vol. 6, Part 2, p. 241, 1959.Google Scholar
5. Newman, B. G. Flow in a Viscous Vortex. Aeronautical Quarterly, Vol. X, p. 149, May 1959.Google Scholar
6. Lamb, H. Hydrodynamics, 6th Edition, Cambridge University Press, 1932.Google Scholar
7. Schlichting, H. Boundary Layer Theory. English Edition, Pergamon Press, p. 488, 1955.Google Scholar
8. Gaspares, E. Viscous Decay of a Vortex. Master's Thesis, Syracuse University, New York, 1960.Google Scholar
9. Bryer, D. W., Walshe, D. E. and Garner, H. C. Pressure Probes Selected for Three- Dimensional Flow Measurement, R. & M. 3037, 1955. Google Scholar
10. Spreiter, J. R. and Sacks, A. H. The Rolling Up of the Trailing Vortex Street and its Effect on the Downwash Behind Wings. Journal of the Aeronautical Sciences, Vol. 18, p. 21, 1951.CrossRefGoogle Scholar
11. Pope, A. Basic Wing and Airfoil Theory. First Edition, McGraw-Hill, p. 209, 1951.Google Scholar
12. Jacobs, E. N., Ward, K. E. and Pinkerton, R. M. The Characteristics of 78 Related Airfoil Sections from Tests in the Variable Density Wind Tunnel, N.A.C.A. Report 460, 1939.Google Scholar
13. Birkhoff, G. Jets, Wakes and Cavities. Academic Press, New York, p. 283, 1957.Google Scholar
14. Forthmann, E. Turbulent Jet Expansion. N.A.C.A. T.M. 789, 1936.Google Scholar