Hostname: page-component-76d6cb85b7-pn7tm Total loading time: 0 Render date: 2026-07-11T20:07:05.046Z Has data issue: false hasContentIssue false
  • English
  • Français

The noise from the large-scale structure of a jet

Published online by Cambridge University Press:  12 April 2006

J. E. Ffowcs Williams  and
A. J. Kempton
J. E. Ffowcs Williams
Affiliation:
Engineering Department, University of Cambridge
A. J. Kempton
Affiliation:
Engineering Department, University of Cambridge Present address: Noise Department, Rolls-Royce Limited, P.O. Box 30, Derby, England.
Get access Rights & Permissions [Opens in a new window]

Abstract

In this paper we assess the importance as a noise source of the well-ordered large-scale structure of a jet. We propose two simple models of the structure: the first emphasizes those features in common with waves that initially grow on an unstable shear layer but eventually saturate and decay, while the second regards the abrupt pairing of eddies as the most significant event in the jet's development. Our models demonstrate the possibility that forcing at one frequency could increase the broad-band noise of a jet, though, for jets with supersonic eddy convection velocities, the sound propagating in the direction of the Mach angle retains the spectrum of the excitation field. These features are consistent with the available experimental data, and strongly support the view that the large-scale structure of jet turbulence provides the dominant contribution to jet noise.

Information

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 84 , Issue 4 , 27 February 1978 , pp. 673 - 694
Copyright
© 1978 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.)

Article purchase

Temporarily unavailable

References

Acton, E. 1976 A modelling of large jet eddies. Ph.D. thesis, Cambridge University.
Bechert, D. & Pfizenmaier, E. 1975 On the amplification of broadband jet noise by a pure tone excitation. J. Sound Vib. 43, 581–587.Google Scholar
Brown, G. L. & Roshko, A. 1974 On density effects and large structures in turbulent mixing layers. J. Fluid Mech. 64, 775–816.Google Scholar
Chan, Y. Y. 1974a Spatial waves in turbulent jets. Phys. Fluids 17, 46–53.Google Scholar
Chan, Y. Y. 1974b Spatial waves in turbulent jets. II. Phys. Fluids 17, 1667–1670.Google Scholar
Crighton, D. G. 1972 The excess noise field of subsonic jets. J. Fluid Mech. 56, 683–694.Google Scholar
Crighton, D. G. 1975 Basic principles of aerodynamic noise generation. Prog. Aerospace Sci. 16, 31–96.Google Scholar
Crighton, D. G. & Gaster, M. 1976 Stability of slowly diverging jet flow. J. Fluid Mech. 77, 397–413.Google Scholar
Crow, S. C. 1972 Acoustic gain of a turbulent jet. Am. Phys. Soc. Meeting, Univ. Colorado, Boulder, paper IE.6.Google Scholar
Crow, S. C. & Champagne, F. H. 1971 Orderly structure in jet turbulence. J. Fluid Mech. 48, 547–591.Google Scholar
Damms, S. M. & KÜCHEMANN, D. 1974 On a vortex-sheet model for the mixing between two parallel streams. I. Description of the model and experimental evidence. Proc. Roy. Soc. A 339, 451–461.Google Scholar
Lau, J. C. & Fisher, M. J. 1975 The vortex-sheet structure of turbulent jets. Part 1. J. Fluid Mech. 67, 299–337.Google Scholar
Lau, J. C., Fuchs, H. V. & Fisher, M. J. 1972 The intrinsic structure of turbulent jets. J. Sound Vib. 22, 379–406.Google Scholar
Laufer, J., Kaplan, R. E. & Chu, W. T. 1973 On the generation of jet noise. Specialists’ Meeting ‘Noise Mechanisms’, Brussels. AGARD Rep. no. CP 131, paper 21.Google Scholar
Lighthill, M. J. 1952 On sound generated aerodynamically. I. General theory. Proc. Roy. Soc. A 211, 564–587.Google Scholar
Lighthill, M. J. 1954 On sound generated aerodynamically. II. Turbulence as a source of sound. Proc. Roy. Soc. A 222, 1–32.Google Scholar
Liu, J. T. C. 1974 Developing large-scale wavelike eddies and the near jet noise field. J. Fluid Mech. 62, 437–464.Google Scholar
Mollø-Christensen, E. 1967 Jet noise and shear flow instability seen from an experimenter's viewpoint. J. Appl. Mech. 34, 1–7.Google Scholar
Moore, C. J. 1977 The role of shear-layer instability waves in jet exhaust noise. J. Fluid Mech. 80, 321–367.Google Scholar
Moore, D. W. & Saffmann, P. G. 1975 The density of organized vortices in a turbulent mixing layer. J. Fluid Mech. 69, 465–473.Google Scholar
Petersen, R. A., Kaplan, R. E. & Laufer, J. 1974 Ordered structures and jet noise. N.A.S.A. Contractor Rep. CR-134733.Google Scholar
Powell, A. 1964 Theory of vortex sound. J. Acoust. Soc. Am. 36, 177–195.Google Scholar
Stratanovitch, R. L. 1963 Topics in the Theory of Random Noise, vol. I. Gordon & Breach.
Winant, C. D. & Browand, F. K. 1974 Vortex pairing: the mechanism of turbulent mixing-layer growth at moderate Reynolds number. J. Fluid Mech. 63, 237–255.Google Scholar