Periodic excitation for jet vectoring and enhanced spreading

Latunia G. Pack, Avraham Seifert

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

The effects of periodic excitation on the evolution of a turbulent jet were studied experimentally. A short, wide-angle diffuser was attached to the jet exit and excitation was introduced at the junction between the jet exit and the diffuser inlet. The introduction of high amplitude periodic excitation at the jet exit enhances the mixing and promotes attachment of the jet shear-layer to the diffuser wall. Vectoring is achieved by applying the excitation over a fraction of the circumference of the circular jet, enhancing its spreading rate on the excited side and its tendency to reattach to that side. Static deflection studies demonstrate that the presence of the wide-angle diffuser increases the effectiveness of the added periodic momentum due to a favorable interaction between the excitation, the jet shear-layer and the diffuser wall. This point was further demonstrated by the evolution of a wave packet that was excited in the jet shear-layer. Strong amplification of the wave packet was measured with a diffuser attached to the jet exit. The turbulent jet responds quickly (10-20 msec) to step changes in the level of the excitation input. The response scales with the jet exit velocity and is independent of the Reynolds number. Jet deflection angles were found to be highly sensitive to the relative direction between the excitation and the jet flow and less sensitive to the excitation frequency. The higher jet deflection angles were obtained for a diffuser length of about two diameters and for diffusers with half-angles greater than 15 degrees.

Original languageEnglish
Title of host publication37th Aerospace Sciences Meeting and Exhibit
PublisherAmerican Institute of Aeronautics and Astronautics Inc. (AIAA)
DOIs
StatePublished - 1999
Externally publishedYes
Event37th Aerospace Sciences Meeting and Exhibit, 1999 - Reno, United States
Duration: 11 Jan 199914 Jan 1999

Conference

Conference37th Aerospace Sciences Meeting and Exhibit, 1999
Country/TerritoryUnited States
CityReno
Period11/01/9914/01/99

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