Multiple mode actuation of a turbulent jet

Latunia G. Pack, Avraham Seifert

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


The effects of multiple mode periodic excitation on the evolution of a circular turbulent jet were studied experimentally. A short, wide-angle diffuser was attached to the jet exit. Streamwise and cross-stream excitations were introduced at the junction between the jet exit and the diffuser inlet on opposing sides of the jet. The introduction of high amplitude, periodic excitation in the streamwise direction enhances the mixing and promotes attachment of the jet shear-layer to the diffuser wall. Cross-stream excitation applied over a fraction of the jet circumference can deflect the jet away from the excitation slot. The two modes of excitation were combined using identical frequencies and varying the relative phase between the two actuators in search of an optimal response. It is shown that, for low and moderate periodic momentum input levels, the jet deflection angles depend strongly on the relative phase between the two actuators. Optimum performance is achieved when the phase difference is π±π/6. The lower effectiveness of the equal phase excitation is attributed to the generation of an azimuthally symmetric mode that does not produce the required non-axisymmetric vectoring. For high excitation levels, identical phase becomes more effective, while phase sensitivity decreases. An important finding was that with proper phase tuning, two unsteady actuators can be combined to obtain a non-linear response greater than the superposition of the individual effects.

Original languageEnglish
Title of host publication39th Aerospace Sciences Meeting and Exhibit
PublisherAmerican Institute of Aeronautics and Astronautics Inc. (AIAA)
StatePublished - 2001
Event39th Aerospace Sciences Meeting and Exhibit 2001 - Reno, NV, United States
Duration: 8 Jan 200111 Jan 2001


Conference39th Aerospace Sciences Meeting and Exhibit 2001
Country/TerritoryUnited States
CityReno, NV


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