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Main Title: Properties of a sweeping jet emitted from a fluidic oscillator
Author(s): Ostermann, Florian
Woszidlo, Rene
Nayeri, Christian Navid
Paschereit, Christian Oliver
Type: Article
Language Code: en
Is Part Of: 10.14279/depositonce-7144
Abstract: This experimental study investigates the flow field and properties of a sweeping jet emitted from a fluidic oscillator into a quiescent environment. The aspect ratio of the outlet throat is 1. Stereoscopic particle image velocimetry is employed to measure the velocity field plane-by-plane. Simultaneously acquired pressure measurements provide a reference for phase correlating the individual planes yielding three-dimensional, time-resolved velocity information. Lagrangian and Eulerian visualization techniques illustrate the phase-averaged flow field. Circular head vortices, similar to the starting vortex of a steady jet, are formed repetitively when the jet is at its maximum deflection. The quantitative jet properties are determined from instantaneous velocity data using a cylindrical coordinate system that takes into account the changing deflection angle of the jet. The jet properties vary throughout the oscillation cycle. The maximum jet velocity decays much faster than that of a comparable steady jet indicating a higher momentum transfer to the environment. The entrainment rate of the spatially oscillating jet is larger than for a steady jet by a factor of 4. Most of the mass flow is entrained from the direction normal to the oscillation plane, which is accompanied by a significant increase in jet depth compared to a steady jet. The high entrainment rate results from the enlarged contact area between jet and ambient fluid due to the spatial oscillation. The jet’s total force exceeds that of an idealized steady jet by up to 30 %. The results are independent of the investigated oscillation frequencies in the range from 5 to 20 Hz.
Issue Date: 2018
Date Available: 7-Feb-2019
DDC Class: 532 Mechanik der Fluide, Mechanik der Flüssigkeiten
Subject(s): sweeping jet
fluid oscillator
fundamental flow field
fluidischer Oszillator
fundamentales Strömungsfeld
Journal Title: Journal of fluid mechanics
Publisher: Cambridge University Press
Publisher Place: Cambridge
Volume: 857
Publisher DOI: 10.1017/jfm.2018.739
Page Start: 216
Page End: 238
EISSN: 1469-7645
ISSN: 0022-1120
Notes: Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.
Appears in Collections:FG Experimentelle Strömungsmechanik » Publications

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