The Cone of Silence

Ross Gibson, Nick Keys

Research output: Textual Creative WorksOther contribution

1 Citation (Scopus)


The development of reliable and robust RANS-based jet noise prediction methods is essential for the future design of quieter jet-engine nozzles. The majority of industrial prediction schemes are based on extensions of Lighthill’s acoustic analogy. These RANS-based prediction methods coupled with ray theory have proven to be computationally fast and capable of providing good jet noise predictions. While the use of real rays to calculate propagation effects is not new, the calculation of so-called complex rays-that allow for the modelling of evanescent waves-is typically not accounted for in generic ray programmes. This presents serious shortcomings when dealing with high-speed jets, where high-frequency waves refract away from the downstream axis giving rise to a region exclusive to complex rays commonly referred to as the cone of silence (CoS). While the exponential smallness of these physical complex rays would otherwise justify their neglect, their contribution to the overall jet-noise calculation is critical due to the beaming of source terms in the downstream direction. In this paper we propose an approximate method for modelling the attenuation within the CoS. The method is applied to an isothermal single stream jet computed using RANS. The predictions are compared with experimental data.

Original languageEnglish
Typecreative memoir
Media of outputonline literary journal
PublisherThe Sydney Review of Books
Number of pages13
Place of PublicationSydney, Australia
VolumeMay 2019
ISBN (Print)9781624105883
Publication statusPublished - 6 May 2019

Publication series

Name25th AIAA/CEAS Aeroacoustics Conference, 2019


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