A modelling of the noise from simple coaxial jets, Part 1: With unheated primary flow

The work described in this paper forms a portion of an on-going fundamental study of coaxial jet noise both statically and in flight. Three principal noise-producing regions are identified and their mean flow and turbulence characteristics classified from published data. The noise production from each region is then calculated by using single jet prediction methods for flows of similar mean velocity and turbulence profiles. The initial test of this prediction scheme has been conducted by comparison with data from an unheated, co-planar, coaxial jet configuration. The agreement, in terms of one-third octave spectral predictions, is significantly better than 1 dB over a wide range of both angle of observation and velocity ratio. (C) 1998 Academic Press Limited.