Some fundamental considerations of streamwise vortices found useful in mixing enhancement and jet noise suppression

The present contribution addresses the possibility of extracting more jet noise suppression capabilities of stationary chevron nozzle exits through unsteady excitation of secondary instabilities. An example of insertion of steady streamwise vorticity into a mixing region is given to illustrate its e...

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Bibliographic Details
Published inInternational journal of aeroacoustics Vol. 15; no. 4-5; pp. 515 - 525
Main Author Liu, Joseph TC
Format Journal Article
LanguageEnglish
Published London, England SAGE Publications 01.07.2016
Subjects
unsteady secondary instabilities
streamwise vorticity
chevron nozzle exhaust
unsteady forcing
mixing enhancement
aeroacoustics
noise abatement
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Summary:The present contribution addresses the possibility of extracting more jet noise suppression capabilities of stationary chevron nozzle exits through unsteady excitation of secondary instabilities. An example of insertion of steady streamwise vorticity into a mixing region is given to illustrate its effectiveness in promoting enhanced mixing. Using stability theory as a guide, unsteady secondary instability of the streamwise vorticity is excited with emphasis on nonlinear effects. The averaged combined effect on the steady flow, through the Reynolds stresses, provides significant further enhancement. Possible implementation in the laboratory is discussed as is further extensions of the much-simplified considerations.
ISSN:1475-472X
2048-4003
DOI:10.1177/1475472X16642352