This study is focused on a new approach to control the mixing at the exhaust of a jet nozzle. Two dielectric barrier discharges are used to enhance the turbulent quantities in the jet wake. An axisymmetric airjet is equipped with a 22- degree-angle diffuser that houses two dielectric barrier discharge actuators, symmetrically placed along the lips of the diffuser. Streamwise, cross-stream planes, and turbulent spectra for free air jet velocities from 10 to 40 m/s are investigated by stereoscopic particle image velocimetry and laser Doppler velocimetry up to 8 jet diameters. The airflow is separated naturally along the diffuser wall and the results demonstrate that a full (at 10 m/s) or partial (at 20 m/s) flow attachment can be performed, this process being associated with the shedding of coherent structures. The turbulent spectra suggest that the frequency of the vortex shedding is dictated by the electrical frequency applied to the actuators and that the flow structures can be manipulated up to 40 m/s. The time-averaged data confirm that a significant enhancement of the jet spreading, a jet core length reduction, and a turbulent kinetic energy increase are performed up to 30 m/s for a quasi-steady actuation. Unsteady actuations are also investigated and the results highlight that a Strouhal number from 0.25 to 0.32 is particularly effective to enhance the turbulent kinetic energy in the overall flowfield.
Flow control by dielectric barrier discharge actuators: Jet mixing enhancement
Strömungsregelung durch Entladungsplasma-Aktoren mit dielektrischer Barriere: verstärkte Jet-Durchmischung
AIAA Journal ; 46 , 9 ; 2293-2305
2008
13 Seiten, 19 Bilder, 3 Tabellen, 38 Quellen
Aufsatz (Zeitschrift)
Englisch
Düse , Abgasströmung , Nachlaufströmung , Turbulenz , Luftstrahl , Aktor , Strömungsdiffusor , Teilchenabbildgeschwindigkeitsmessung , Laser-Doppler-Geschwindigkeitsmessung , Luftströmung , Wirbelablösung , Strömungsverlauf , Strahlaufspaltung , kinetische Energie , Strouhal-Zahl , Strömungsfeld , Düsenjäger , Raketentriebwerk
Flow Control by Dielectric Barrier Discharge Actuators: Jet Mixing Enhancement
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