Abstract
Large-scale structures in the form of instability waves are an inherent part of a shearlayer mixing process. Such structures are shown to be present in an acoustically and aerodynamically well behaved jet even at high Mach numbers. They do not directly radiate significant acoustic power in a subsonic jet, but do govern the production of the turbulent fluctuations which radiate broad-band jet noise. Over the whole subsonic Mach number range, a significant increase in jet noise can be produced by exciting the shear layer with a fluctuating pressure at the nozzle of only 0·08 % of the jet dynamic head but with the correct Strouhal number. Such excitation by internal acoustic, aerodynamic or thermal fluctuations could explain the variability of jet noise measurements between different rigs and could also be responsible for some components of ‘excess’ noise.
Publisher
Cambridge University Press (CUP)
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics
Reference52 articles.
1. Schubert, L. K. 1972 Numerical study of sound refraction by a jet flow.J. Acoust. Soc. Am. 51,439–462.
2. Wooldridge, C. E. , Wooten, D. C. & Amaro, A. J. 1971 The structure of jet turbulence producing noise.N.A.S.A. Contractor Rep. no. 126483.
3. Pfizenmaier, E. 1973 On the instability of a sound influenced free jet.E.S.R.O. Tech. Trans. no. 122. (Translation of DFVLR Berlin Rep. DLR-FB 73–69.)
4. Jones, B. G. & Planchon, H. P. 1971 A study of the local pressure field in turbulent shear flow and its relation to aerodynamic noise generation.N.A.S.A. Contractor Rep. no. 134493.
5. Lighthill, M. J. 1961 Sound generated aerodynamically. Bakerian Lecture.Proc. Roy. Soc. A 267,147–182.
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