Hostname: page-component-cd9895bd7-dk4vv Total loading time: 0 Render date: 2024-12-19T06:22:57.633Z Has data issue: false hasContentIssue false
  • English
  • Français

Helical instabilities of slowly divergent jets

Published online by Cambridge University Press:  19 April 2006

Peter Plaschko
Peter Plaschko
Affiliation:
Hermann Föttinger Institut für Thermo- u. Fluiddynamik, Technische Universität Berlin, West Germany
Get access Rights & Permissions [Opens in a new window]

Abstract

The inviscid spatial growth of spiral modes of circular, slowly diverging jets is analysed. A multiple-scales expansion is used to develop a linear stability study for non-axisymmetric disturbances of arbitrary helicity. The numerical evaluation is restricted to axisymmetric modes and to the first two helical modes. It is shown that in the case of comparatively high values of the Strouhal number the modes exhibit a very rapid growth and reach their maximal amplification after a short distance, the axisymmetric instabilities being excited more strongly than their spiral counterparts. Contrary to this, the modes grow comparatively slowly in the case of smaller values of the Strouhal number and exhibit their maximal amplification further downstream. In the latter case the first spiral mode is more unstable than the axisymmetric one. A comparison with experiments seems to support these results.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 92 , Issue 2 , 28 May 1979 , pp. 209 - 215
Copyright
© 1979 Cambridge University Press

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

Armstrong, R. R. 1977 Einfluss der Machzahl auf die kohärente Turbulenzstruktur eines runden Freistrahles. Ph.D. thesis, University of Berlin.
Bouthier, M. 1972 J. Méc. 11, 599.
Chan, Y. Y. 1974 Phys. Fluids 17, 46.
Chan, Y. Y. 1977 A.I.A.A. J. 15, 992.
Crighton, D. G. & Gaster, M. 1976 J. Fluid Mech. 77, 397.
Crow, S. C. & Champagne, F. H. 1971 J. Fluid Mech. 48, 547.
Michalke, A. 1971 Z. Flugwiss. 19, 319.
Moore, C. J. 1977 J. Fluid Mech. 80, 321.