Identification of nonlinear and near-field effects in jet noise using nonlinearity indicators

Kent L. Gee, Micah R. Shepherd, Lauren E. Falco, Anthony A. Atchley, Lawrence S. Ukeiley, Bernard J. Jansen, John M. Seiner

Research output: Chapter in Book/Report/Conference proceedingConference contribution

11 Scopus citations

Abstract

In the collection and analysis of high-amplitude jet noise data for nonlinear acoustic propagation, both model-scale and full-scale measurements have limitations. Model-scale measurements performed in anechoic facilities are usually limited by transducer and data acquisition system bandwidths and maximum propagation distance. The accuracy of fullscale measurements performed outdoors is reduced by ground reflections and atmospheric effects. This paper describes the use of two nonlinearity indicators as complementary to ordinary spectral analysis of jet noise propagation data. The first indicator is based on an ensemble-averaged version of the generalized Burgers equation. The second indicator is the bicoherence, which is a normalized version of the bispectral density. These indicators are applied to Mach-0.85 and Mach-2.0 unheated jet noise data collected at the National Center for Physical Acoustics. Specifically, the indicators are used to separate geometric near-field effects from nonlinear propagation effects for the Mach-2.0 data, which cannot be done conclusively using comparisons of power spectral densities alone.

Original languageEnglish (US)
Title of host publication13th AIAA/CEAS Aeroacoustics Conference (28th AIAA Aeroacoustics Conference)
StatePublished - 2007
Event13th AIAA/CEAS Aeroacoustics Conference (28th AIAA Aeroacoustics Conference) - Rome, Italy
Duration: May 21 2007May 23 2007

Publication series

Name13th AIAA/CEAS Aeroacoustics Conference (28th AIAA Aeroacoustics Conference)

Other

Other13th AIAA/CEAS Aeroacoustics Conference (28th AIAA Aeroacoustics Conference)
CountryItaly
CityRome
Period5/21/075/23/07

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering
  • Mechanical Engineering

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