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The generation of sound by two-phase nozzle flows and its relevance to excess noise of jet engines

Published online by Cambridge University Press:  29 March 2006

O. J. Whitfield  and
M. S. Howe
O. J. Whitfield
Affiliation:
Engineering Department, University of Cambridge Present address: Mechanical Engineering Laboratory, G.E.C. Power Engineering, Cambridge Road, Whetstone, Leicestershire.
M. S. Howe
Affiliation:
Engineering Department, University of Cambridge
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Abstract

This paper describes a prototype model experiment designed to test the principle that the ‘excess’ noise of a jet issuing from a conical nozzle can be significantly diminished by reducing the maximum pressure gradient in the flow. The experiment uses a water jet containing flow inhomogeneities in the form of air or helium bubbles exhausting through a conventional conical nozzle or a specially contoured ‘bellmouth’ nozzle. It is argued that the level of the internally generated noise is controlled by the mean-flow pressure gradient, and substantial reductions in the sound level are recorded with the bellmouth nozzle. Certain features of the acoustic pressure signatures of the two-phase flow are examined in detail, in particular a rather surprising absolute difference in the sound pressure levels produced when helium rather than air bubbles are used under otherwise identical mean-flow conditions. Theoretical arguments are advanced which appear to explain the principal features of the observations.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 75 , Issue 3 , 11 June 1976 , pp. 553 - 576
Copyright
© 1976 Cambridge University Press

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References

Batchelor, G. K. 1967 An Introduction to Fluid Dynamics. Cambridge University Press.
Batchelor, G. K. 1969 Compression waves in a suspension of gas bubbles in liquid. In Fluid Dyn. Trans. (ed. W. Fiszdon, p. Kucharczyk & W. J. Prosnak), vol. 4, p. 425. Warsaw: Polish Scientific Publishers.
Candel, S. M. 1972 Analytical studies of some acoustic problems of jet engines. Ph.D. thesis, Cal. Inst. Tech., Pasadena.
Carstensen, F. L. & Foldy, L. L. 1947 J. Acoust. Soc. Am. 19, 481.
Chapman, R. B. & Plesset, M. S. 1970 Thermal effects in the free oscillation of gas bubbles. Div. Engng Appl. Sci., Cal. Inst. Tech. Rep. no. 85–810.Google Scholar
Crighton, D. G. & FFOWCS WILLIAMS, J. E. 1969 J. Fluid Mech. 36, 585.
Cumpsty, N. A. 1974 Excess noise from gas turbine exhausts. Aero. Res. Counc. 35, 726, N939.Google Scholar
Cumpsty, N. A. & Marble, F. E. 1974 The generation of noise by the fluctuations in gas temperature into a turbine. Cambridge University, Engng Lab. Rep. CUED/A TURBO/TR57.Google Scholar
Devin, C. 1959 J. Acoust. Soc. Am. 31, 1654.
Dils, R. R. 1973 Dynamic gas measurements in a gas turbine transition duct exit. A.S.M.E. Paper, no. 73–GT–7.Google Scholar
Dowling, A. 1976 J. Fluid Mech. 74, 529.
Ffowcs Williams, J. E. & Howe, M. S. 1975 J. Fluid Mech. 67, 597.
Ffowcs Williams, J. E., Simson, J. & Virchis, V. 1975 J. Fluid Mech. 71, 251.
Fox, F. E., Curley, S. R. & Larson, G. S. 1955 J. Acoust. Soc. Am. 27, 534.
Hall, L. H. 1969 Flow noise. Ph.D. thesis, Imperial College, London.
Hinze, J. O. 1955 A. I. Ch. E. J. 1, 289.
Hoch, R. & Hawkins, R. 1973 Recent studies into Concorde noise reduction. AGARD Conf. Proc. no. 131, paper 19.Google Scholar
Howe, M. S. 1975 J. Fluid Mech. 71, 625.
Lighthill, M. J. 1952 Proc. Roy. Soc. A, 221, 564.
Macpherson, J. D. 1957 Proc. Phys. Soc. Lond. B 70, 35, 1953.
Meyer, E. & Skudrzyk, E. 1953 Akust. Beihefte, 3, 434.
Minnaert, M. 1933 Phil. Mag. 16, 235.
Morfey, C. L. 1973 J. Sound Vib. 31, 391.
Pickett, G. F. 1974 Turbine noise due to turbulence and temperature fluctuations. Paper 8th Int. Cong. Acoustics, London.
Silberman, E. 1957 J. Acoust. Soc. Am. 29, 925.
Strasberg, M. 1953 J. Acoust. Soc. Am. 25, 536.
Strasberg, M. 1956 J. Acoust. Soc. Am. 28, 20.
Tangren, R. F., Dodge, C. H. & Seifert, H. S. 1949 J. Appl. Phys. 20, 637.
Wallis, G. B. 1969 One-Dimensional Two-Phone Flow. McGraw-Hill.
Whitfield, O. J. 1975 Novel schemes for jet noise control. Ph.D. thesis, Engineering Department, University of Cambridge.
Wijngaarden, L. Van 1972 One-dimensional flow of liquids containing small gas bubbles Ann. Rev. Fluid Mech. 4, 369.Google Scholar