Jet mixing noise: a review of single stream temperature effects

Tester, B.J. and Morfey, C.L. (2009) Jet mixing noise: a review of single stream temperature effects. In Proceedings of the 15th AIAA/CEAS Aeroacoustics Conference (30th AIAA Aeroacoustics Conference). American Institute of Aeronautics and Astronautics. 41 pp .

Abstract

The work of Viswanathan and others in recent years has raised serious
questions about jet noise databases such as that of Tanna - the two underlying
concerns being noise contamination and the effect of Reynolds number - and as
a result it has been argued that the effects of temperature have been
misunderstood in the past. In this paper, we have compared the Tanna data
with that of QinetiQ [1983], which has a similar nozzle size and hence Reynolds
number to that of the data of Viswanathan and although we find similar
differences, we argue there are other reasons for this. Apart from extensive rig
validation, Tanna & Morris repeated their static tests with a simulated flight
stream and a substantial flight effect was observed. This would not have been
possible if there had been significant noise contamination. In fact, these
differences are more likely due to some other effect related to comparing data
from two different facilities and/or two different nozzles, as shown by Bridges &
Brown and discussed in depth by Harper-Bourne at this conference. It is
concluded the available experimental evidence still strongly indicates the
presence of an additional dipole source due to heating that scales on the sixth
power of jet velocity. A brief review of recent flow-acoustic interaction
computations based on the Lilley-Goldstein equation has confirmed that flowacoustic
interactions cannot be the main reason for the effects of heating at low
velocity ratios even though the quadrupole source in sheared flow is clearly
‘amplifying’ the sound radiation at low frequencies. Finally convective
amplification effects are briefly considered in both isothermal and heated jets

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