Journal ArticleDOI
The formation and evolution of synthetic jets
Barton L. Smith,Ari Glezer +1 more
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In this article, a nominally plane turbulent jet is synthesized by the interactions of a train of counter-rotating vortex pairs that are formed at the edge of an orifice by the time-periodic motion of a flexible diaphragm in a sealed cavity.Abstract:
A nominally plane turbulent jet is synthesized by the interactions of a train of counter-rotating vortex pairs that are formed at the edge of an orifice by the time-periodic motion of a flexible diaphragm in a sealed cavity. Even though the jet is formed without net mass injection, the hydrodynamic impulse of the ejected fluid and thus the momentum of the ensuing jet are nonzero. Successive vortex pairs are not subjected to pairing or other subharmonic interactions. Each vortex of the pair develops a spanwise instability and ultimately undergoes transition to turbulence, slows down, loses its coherence and becomes indistinguishable from the mean jet flow. The trajectories of vortex pairs at a given formation frequency scale with the length of the ejected fluid slug regardless of the magnitude of the formation impulse and, near the jet exit plane, their celerity decreases monotonically with streamwise distance while the local mean velocity of the ensuing jet increases. In the far field, the synthetic jet i...read more
Citations
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Experimental Characterization of Sub-Millimetric Fluidic Actuators: Application to Boundary Layer Separation Control
TL;DR: In this article, the authors compared submillimetric synthetic, continuous, and pulsed-jet actuators under identical conditions of generation and found that the efficiency of the fluidic action on the reattachment of the boundary layer is strongly dependant on the type of the jet.
Computational Modeling of Synthetic Jets
David C. Durán,Omar D. López +1 more
TL;DR: In this article, a tridimensional model of a piezoelectric disk was used to analyze the influence of the relevant dimensionless numbers in the synthetic jet formation when the disk was excited at low frequencies.
Journal ArticleDOI
Enhancing forced-convection heat transfer of a channel surface with synthetic jet impingements
TL;DR: In this paper , a transient numerical simulation was carried out to investigate the convection heat transfer enhancement of a heated surface in an airflow channel using a synthetic jet, which was performed with a channel-flow average velocity varying up to 3 m/s, which has the corresponding channel Reynolds number of 3,616.
Performance of Airfoils at Low Angles of Attack: Trailing Edge Trapped Vortices
TL;DR: In this article, a small Gurney flap is mounted on the pressure side of the airfoil just upstream of its trailing edge to leverage the trapped vortices induced by the flap near the trailing edge.
References
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Journal ArticleDOI
An Album of Fluid Motion
Milton van Dyke,Frank M. White +1 more
TL;DR: In this paper, the authors present a visualisation de l'ecoulement for tourbillon and dynamique des: fluides, aubes, cylindre, instabilite.
Journal ArticleDOI
Streamwise vortex structure in plane mixing layers
Luis P. Bernal,Anatol Roshko +1 more
TL;DR: In this paper, it is shown that superimposed on the primary, spanwise vortex structure there is a secondary, steam wise vortex structure, and the spatial organization of the secondary structure produces a well-defined spanwise entrainment pattern in which fluid from each stream is preferentially entrained at different spanwise locations.
Journal ArticleDOI
The planar turbulent jet
Ephraim Gutmark,Israel Wygnanski +1 more
TL;DR: In this article, hot-wire measurements in a plane incompressible jet are reported, where the flow was found to be self-preserving beyond x/d > 40 and measurements were made up to x/D = 120.
Journal ArticleDOI
The structure of a self-preserving turbulent plane jet
TL;DR: The structure of a self-preserving turbulent plane jet exhausting into a slow-moving parallel airstream is studied in this paper, where results of turbulence measurements and the structure is compared with that of the plane wake.
Journal ArticleDOI
Preferred modes and the spreading rates of jets
Ephraim Gutmark,Chih-Ming Ho +1 more
TL;DR: In this article, it is suggested that extremely low-level spatially coherent disturbances in individual facilities change the initial conditions of a laminar shear layer and result in the discrepancies reported in the literature.