Noise control using adjoint-based optimization

M. Wei, J. B. Freund

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


Attempts to control the jet noise have been hampered by an insufficent understanding of its mechanisms, resulting in a reliance on trial-and-error experimentation to reduce noise. This paper aims to explore the noise mechanism using adjoint-based noise control in conjunction with a direct numerical simulation. A control problem is formulated with the objective of reducing acoustic intensity on a line in the sound field. The cost function that quantifies this is used to force the adjoint of the compressible flow equation, which are solved numerically in the same way we solve the flow equations. The adjoint variables provide the sensitivity of the noise, as we have specifically defined it, to changes in actuation. Using this approach, the noise radiated from a two-dimensional mixing layer with convective Mach number Mc = 0:4 and Reynolds number based on vorticity thickness Reω = 500 was reduced by 6.3dB. This flow is a model of the near nozzle region of a jet and generalization of the technique to a jet is straightforward. Despite the substantial reduction in the noise, the changes of the flow field are small, as seen by examination of the turbulence kinetic energy and the momemtum thickness before and after control is applied. We conclude that the controler makes subtle changes to the radiating portion of the flow without drastically altering its energetics. Our preliminary investigations into the nature of the automatically identified control reveal little of how it works.

Original languageEnglish (US)
Title of host publication8th AIAA/CEAS Aeroacoustics Conference and Exhibit
PublisherAmerican Institute of Aeronautics and Astronautics Inc.
ISBN (Print)9781624101199
StatePublished - 2002
Externally publishedYes
Event8th AIAA/CEAS Aeroacoustics Conference and Exhibit, 2002 - Breckenridge, CO, United States
Duration: Jun 17 2002Jun 19 2002

Publication series

Name8th AIAA/CEAS Aeroacoustics Conference and Exhibit


Other8th AIAA/CEAS Aeroacoustics Conference and Exhibit, 2002
Country/TerritoryUnited States
CityBreckenridge, CO

ASJC Scopus subject areas

  • Aerospace Engineering
  • Electrical and Electronic Engineering
  • Mechanical Engineering
  • Acoustics and Ultrasonics


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