Investigating broadband shock-associated noise of axisymmetric jets using large-eddy simulation

Daniel J. Bodony, Jaiyoung Ryu, Sanjiva K. Lele

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

Abstract

A supersonic jet operated at an off-design condition supports a standing wave pattern of alternating compression and expansion waves, often called shock-cells. The interaction of turbulence with the shock-cells leads to an additional source of broadband noise that is preferentially radiated upstream, i.e. towards the engine. In commercial aircraft this condition occurs in the fan stream at the cruise-climb condition and adversely impacts passenger comfort in the forward cabin section. In military aircraft the extra acoustic loading on the aft structures leads to reduced life cycle times. An unheated jet with a design Mach number of 1.95 is studied at on-and off-design conditions; for the latter case the underexpanded jet has a fully expanded Mach number of 2.2. The near-fields of the jets are studied with respect to their mean, fluctuation, and spectral characterizations. It is observed that the shear layers of the off-design jet merge one diameter downstream of the on-design jet with a slight reduction in the peak level of velocity fluctuation. The spectral content of the velocity and pressure field, inferred from axial two-point measurements, of both jets is similar. The underexpanded jet differs, however, in that it supports Mach wave radiation stemming from supersonically-convecting instability waves. It is observed that the Mach waves significantly contribute to the near-field pressure.

Original languageEnglish (US)
Title of host publicationCollection of Technical Papers - 12th AIAA/CEAS Aeroacoustics Conference
Pages1216-1226
Number of pages11
StatePublished - Dec 27 2006
Externally publishedYes
Event12th AIAA/CEAS Aeroacoustics Conference - Cambridge, MA, United States
Duration: May 8 2006May 10 2006

Publication series

NameCollection of Technical Papers - 12th AIAA/CEAS Aeroacoustics Conference
Volume2

Other

Other12th AIAA/CEAS Aeroacoustics Conference
CountryUnited States
CityCambridge, MA
Period5/8/065/10/06

ASJC Scopus subject areas

  • Engineering(all)

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