Hostname: page-component-cd9895bd7-8ctnn Total loading time: 0 Render date: 2024-12-26T06:28:57.064Z Has data issue: false hasContentIssue false
  • English
  • Français

The near field within the potential cone of subsonic cold jets

Published online by Cambridge University Press:  29 March 2006

N. W. M. Ko  and
P. O. A. L. Davies
N. W. M. Ko
Affiliation:
Institute of Sound and Vibration Research, University of Southampton Present address: Department of Mechanical Engineering, University of Hong Kong, Hong Kong.
P. O. A. L. Davies
Affiliation:
Institute of Sound and Vibration Research, University of Southampton
Get access Rights & Permissions [Opens in a new window]

Abstract

This investigation describes a detailed study of the near pressure field within the potential cone of a subsonic circular turbulent jet.

The components of the near pressure field in the potential cone in which the potential flow condition exists within the fist four and a half diameter downstream appear to be moving with a phase velocity equal to the local speed of sound. The direction of propagation is roughly normal to the shear layer surrounding the cone. Some components of the hot-wire signal can be associated with the jet structure as a simple complex source, while others are related to the local characteristics of turbulence. Differences in the characteristics of the pressure field within the potential cone exist between the vortex generated noise at very low jet velocity and the eddy generated noise at higher velocity.

The power spectra obtained in the potential cone show the peak which is due to the pressure fluctuations and the flat portion due to the turbulence. The frequencies of the dominant components, in terms of the Strouhal number, are functions of both the axial and radial positions.

Microphone measurements were made in the near field outside for detailed comparison with the potential cone results.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 50 , Issue 1 , 15 November 1971 , pp. 49 - 78
Copyright
© 1971 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

Allcock, G. A., Tanner, P. L. & McLachlan, K. R. 1962 A general purpose analogue correlator for the analysis of random noise signals. University of Southumpton. Aero. Astr. Rep. 205.Google Scholar
Bose, B. 1968 Experimental study of the wave-like characteristics of turbulence in shear layers and behind grids. Ph.D. thesis, University of Southampton.
Bradshaw, P., Ferriss, D. H. & Johnson, R. F. 1964 Turbulence in the noise-producing region of a circular jet. J. Fluid Mech. 19, 591–624.Google Scholar
Davies, P. O. A. L. & Fisher, M. J. 1964 Heat transfer from electrically-heated cylinders Proc. Roy. Soc. A 280, 486–527.Google Scholar
Davies, P. O. A. L., Fisher, M. J. & Barratt, M. J. 1963 The characteristics of the turbulence in the mixing region of a round jet. J. Fluid Mech. 15, 337–367.Google Scholar
Davies, P. O. A. L. & Ko, N. W. M. 1965 The near field generated by intense turbulence. 5th Int. Congress Acoustics, Leige, paper L53.
Davies, P. O. A. L., Ko, N. W. M. & Bose, B. 1967 The local pressure field of turbulent jets. Aero. Res. Counc. Lond. 29065. N. 518. Also 1968 Aero. Res. Counc. Current Paper no. 989.Google Scholar
Ffowcs Williams, J. E. 1960 On convected turbulence and its relation to near field pressure. University of Southampton, U.S.A.A. Rep. 109. Fisher, M. J. & Davies, P. O. A. L. 1964 Correlation measurements in a non-frozen pattern of turbulence. J. Fluid Mech. 18, 97–116.Google Scholar
Franklin, R. E. & Foxwell, F. H. 1958 Correlation in the random pressure field close to a jet. Aero. Res. Counc. Lond. R & M 3161.Google Scholar
Howes, W. L., Callaghan, E. E., Coles, W. D. & Mull, H. R. 1957 Near noise field of a jet engine exhaust. N.A.C.A. Rep 1338.Google Scholar
Hubbard, H. H. & Lassiter, L. W. 1953 Experimental studies of jet noise. J. Acous. Soc. Am. 25, 381–384.Google Scholar
Ko, N. W. M. 1969 The near field structure of subsonic cold jets. Ph.D. thesis. University of Southampton.
Ko, N. W. M. & Davies, P. O. A. L. 1971 Interference effect of hot wires. IEEE Transactions on Instrumentation and Measurement. IM-20 (1), 76-78.
Lassiter, L. W. & Hubbard, H. H. 1956 The near noise field of static jets and some model studies of devices for noise reduction. N.A.C.A. Rep. 1261.Google Scholar
Laurence, J. C. 1956 Intensity, scale and spectra of turbulence in the mixing region of a free subsonic jet. N.A.C.A. Rep. 1292.Google Scholar
Mollo-Christensen, E. 1963 Measurement of near field pressure of subsonic jets. A.G.A.R.D. Rep. 449.Google Scholar
Mollo-Christensen, E., Kolpin, M. A. & Martuccelli, J. R. 1964 Experiments on jet flows and jet noise for field spectra and directivity patterns. J. Fluid Mech. 18, 285–301.Google Scholar