Hostname: page-component-cd9895bd7-q99xh Total loading time: 0 Render date: 2024-12-19T03:45:22.497Z Has data issue: false hasContentIssue false
  • English
  • Français

Heat diffusion as a source of aerodynamic sound

Published online by Cambridge University Press:  11 April 2006

A. J. Kempton
A. J. Kempton
Affiliation:
Engineering Department, University of Cambridge
Get access Rights & Permissions [Opens in a new window]

Abstract

The paper examines the role of heat diffusion as an internal noise source in aeroengines and as a source of noise in the mixing of hot jets. We consider a number of model problems and find that the sound induced by unsteady heat transfer can show an unusually weak dependence on the mean flow velocity U, the intensity scaling as U3 in three dimensions. At low enough velocities diffusion effects will overwhelm other noise sources, but we have failed in our search for a significant practical situation in which we can prove that sound generated by diffusion clearly dominates over that excited by unsteady aerodynamic forces; they are sometimes comparable.

We examine the possibility that diffusive monopole sources feature in the noise of hot jets using model problems in the linear case and using dimensional analysis in the nonlinear case, and conclude that no significant monopole exists when the specific heats are constant. But they are not constant at low frequencies when, for example, heat flows into and out of vibrational energy modes; then an important monopole source is present. This source shows an unusually complicated scale effect.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 78 , Issue 1 , 5 November 1976 , pp. 1 - 31
Copyright
© 1976 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

Chapman, A. J. 1974 Heat Transfer. Macmillan.
Clarke, J. F. & McChesney, M. 1964 The Dynamics of Real Gases. Butterworths.
Cremer, L. 1948 Über die akustische Grenzschicht vor starren Wänden. Arch. Elektr. Übertragung, 2, 136–139.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
Cumpsty, N. A. & Marble, F. E. 1974 The generation of noise by the fluctuations in gas temperature into a turbine. Cambridge Univ. Engng Dept. Rep. CUED/A TURBO/TR 57.
Ffowcs Williams, J. E. 1974 Sound production at the edge of a steady flow. J. Fluid Mech. 66, 791–816.Google Scholar
Ffowcs Williams, J. E. & Hall, L. H. 1970 Aerodynamic sound generation by turbulent flow in the vicinity of a scattering half-plane. J. Fluid Mech. 40, 657–670.Google Scholar
Ffowcs Williams, J. E. & Howe, M. S. 1974 The generation of sound by density inhomogeneities in low Mach number nozzle flows. J. Fluid Mech. 70, 605–622.Google Scholar
Gersten, K. 1965 Heat transfer in laminar boundary layers with oscillating outer flow. AGARD Meeting: Recent Developments in Boundary Layer Res., part 1, pp. 423–476.
Goldstein, S. 1965 Modern Developments in Fluid Dynamics. Dover.
Herzfeld, K. H. & Litovitz, T. A. 1959 Absorption and Dispersion of Ultrasonic Waves. Academic.
Hoch, R. G., Duponchell, J. P., Cocking, B. J. & Bryce, W. D. 1973 Studies of the influence of density on jet noise. J. Sound Vib. 28, 649–668.Google Scholar
Howe, M. S. 1975 Contributions to the theory of aerodynamic sound with application to excess jet noise and the theory of the flute. J. Fluid Mech. 71, 625–674.Google Scholar
Landau, L. D. & Lifshitz, E. M. 1958 Statistical Physics. Course of Theoretical Physics, vol. 5. Pergamon.
Landau, L. D. & Lifshitz, E. M. 1959 Fluid Mechanics. Course of Theoretical Physics, vol. 6. Pergamon.
Levine, H. & Schwinger, J. 1948 On the radiation of sound from an unflanged circular pipe. Phys. Rev. 73, 383–406.Google Scholar
Lighthill, M. J. 1952 On sound generated aerodynamically. Part I. General theory. Proc. Roy. Soc. A 211, 564–587.Google Scholar
Lighthill, M. J. 1954 On sound generated aerodynamically. Part II. Turbulence as source of sound. Proc. Roy. Soc. A 222, 1–32.Google Scholar
Lighthill, M. J. 1956 Viscosity effects in sound waves of finite amplitude. In Surveys in Mechanics (ed. Batchelor & Davies), p. 250. Cambridge University Press.
Lllley, G. M. 1973 On the noise from jets. AGARD Rep. CP 131, paper 13.Google Scholar
Lush, P. M. & Fisher, M. J. 1973 Noise from hot jets. AGARD Rep. CP 131, paper 12.Google Scholar
Mani, R. 1974 The jet density exponent issue for the noise of heated subsonic jets. J. Fluid Mech. 64, 611–622.Google Scholar
Mani, R. 1976a The influence of jet flow on jet noise. Part 1. The noise of unheated jets. J. Fluid Mech. 73, 753–778.Google Scholar
Mani, R. 1976b The influence of jet flow on jet noise. Part 2. The noise of heated jets. J. Fluid Mech. 73, 779–793.Google Scholar
Morfey, C. L. 1973 Amplification of aerodynamic noise by convected flow inhomogeneities. J. Sound Vib. 31, 391–397.Google Scholar
Morfey, C. L. 1974 Sound radiation from turbulent jets at low Mach number. 8th Int. Congr. Acoustics, London.Google Scholar
Morfey, C. L. 1976 Sound radiation due to unsteady dissipation in turbulent flows. J. Sound Vib. 48, 95–111.Google Scholar
Morse, P. M. & Ingard, K. U. 1968 Theoretical Acoustics. McGraw-Hill.
Noble, B. 1958 Methods Based on the Wiener—Hopf Technique for the Solution of Partial Differential Equations. Pergamon.
Obermeier, F. 1975 Sound generation by heated subsonic jets. J. Sound Vib. 41, 463–472.Google Scholar
Phillips, O. M. 1960 On the generation of sound by supersonic turbulent shear layers. J. Fluid Mech. 9, 1–28.Google Scholar
Rayleigh, Lord 1877 The Theory of Sound. Macmillan. (Reprinted by Dover, 1945.)
Rott, N. 1969 Damped and thermally driven acoustic oscillations in wide and narrow tubes. Z. angew. Math. Phys. 20, 230–243.Google Scholar
Tester, B. J. & Morfey, C. L. 1976 Developments in jet noise modelling — theoretical predictions and comparisons with measured data. J. Sound Vib. 46, 79–103.Google Scholar