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The generation of sound by aerodynamic sources in an inhomogeneous steady flow

Published online by Cambridge University Press:  29 March 2006

M. S. Howe
M. S. Howe
Affiliation:
Engineering Department, University of Cambridge
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Abstract

This paper examines the effect of steady flow on the generation of sound by aerodynamic sources located in the neighbourhood of a scattering body. The analysis is facilitated by the use of a reverse-flow reciprocal theorem which is valid for a certain class of inhomogeneous flow problems. In the case of acoustic ‘bremsstrahlung’, in which sound is generated during the passage of a silent fluid inhomogeneity, such as an entropy spot, past an obstacle in the flow, an elegant discussion of the interaction can be given in terms of a renormalized Green's function. Here the effect of the obstacle is equivalent to a local distortion of the geometry of the three-dimensional space occupied by the medium, the extent of which governs the properties of the acoustic radiation. This is illustrated by means of a detailed analysis of the sound generated during the unsteady convection of a source of constant strength through a neck in a duct.

Information

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 67 , Issue 3 , 11 February 1975 , pp. 597 - 610
Copyright
© 1975 Cambridge University Press

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References

Batchelor, G. K. 1970 An Introduction to Fluid Dynamics. Cambridge University Press.
Blophintsev, D. I. 1946 N.A.C.A. Tech. Memo. no. 1399.
Crighton, D. G. & Leppington, F. G. 1970 J. Fluid Mech. 43, 721.
Crighton, D. G. & Leppington, F. G. 1973 Proc. Roy. Soc. A 335, 313.
Ffowcs Williams, J. E. 1963 Phil. Trans. A 255, 469.
Ffowcs Williams, J. E. 1974 J. Fluid Mech. 66, 791.
Ffowcs Williams, J. E. & Hall, L. H. 1970 J. Fluid Mech. 40, 657.
Ffowcs Williams, J. E. & Hawkings, D. L. 1969 Phil. Trans. A 264, 321.
Ffowcs Williams, J. E. & Lovely, J. 1974 Sound radiated into moving flow by compact surface vibrations. To appear.
Flax, A. H. 1952 J. Aero. Sci. 19, 361.
Helmholtz, H. 1860 Crelle, 58, 1.
Jones, D. S. 1964 The Theory of Electromagnetism. Pergamon.
Lighthill, M. J. 1952 Proc. Roy. Soc. A 221, 564.
Lighthill, M. J. 1954 Proc. Roy. Soc. A 222, 1.
Miles, J. W. 1959 Potential Theory of Unsteady Supersonic flow. Cambridge University Press.
Morse, P. M. & Ingard, K. U. 1968 Theoretical Acoustics. McGraw-Hill.
Ogilvie, T. S. 1973 Z. angew. Math. Mech. 53, 573.
Rayleigh, Lord 1873 Proc. Lond. Math. Soc. 4, 357.
Rayleigh, Lord 1876 Proc. Roy. Soc. 25, 118.