Abstract
A new opposite facing oscillator pair is presented where shared feedback channels enable synchronized sweeping of the exiting jets. The design has no moving parts and the oscillator pair is composed in a back-to-back configuration. The synchronized operation generates a near-field acoustic tonality and the objective is to determine the emitted directivity. The acoustic generation mechanisms were determined using compressible large eddy simulations, which was validated with hot-wire and microphone measurements. Different Reynolds number (Re) conditions up to 21,250 were analyzed for a synchronized oscillation with Strouhal number (St) of order 0.01. Dominant acoustic sources emerging during synchronized sweep oscillation were classified by the interpretation of directivity patterns for a selected flow rate. The near-field directivity pattern could be decomposed as a periodic signal consisting of one acoustic mode with a dipole-like pattern, showing two major lobes associated with the jet sweeping oscillation frequency: one acoustic monopole-like directivity for the first overtone; and dipole-like directivity with two lobes for the second harmonic. It is shown that the acoustic sources are generated by the synchronized pressure oscillation of the exiting jets. The vortical structures inside the fluidic oscillator interact with the non-slip walls. These manipulate the curvature of the central jet and causes an unsteady loading towards the discharge. The new fluidic oscillator design gives synchronized exiting sweeping jets and a large flow length scale near-field directivity pattern. These features give feedback type fluidic oscillators a wider application range.
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28 August 2020
The article Aeroacoustic Characteristics of a Synchronized Fluidic Oscillator written by Elias Sundstrom and Mehmet N. Tomac, was originally published online on 28th June 2020 with Open Access under a Creative Commons Attribution (CC BY) license 4.0.
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Acknowledgements
The authors would like to thank Dr. Liran Oren at the University of Cincinnati for providing access to the CTA and the microphone measurement systems. The design used in this work is from a US Patent application (16/157,460) filed by The Ohio State University Technology Commercialization Office on October 11, 2018.
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The original version of this article was revised: The article Aeroacoustic Characteristics of a Synchronized Fluidic Oscillator written by Elias Sundstrom and Mehmet N. Tomac, was originally published online on 28th June 2020 with Open Access under a Creative Commons Attribution (CC BY) license 4.0. With the authors' decision to cancel Open Access the copyright of the article changed on 18th August 2020 to © Springer Nature B.V. with all rights reserved.
The article Aeroacoustic Characteristics of a Synchronized Fluidic Oscillator written by Elias Sundstrom and Mehmet N. Tomac, was originally published online on 28th June 2020 with Open Access under a Creative Commons Attribution (CC BY) license 4.0. With the authors’ decision to cancel Open Access the copyright of the article changed on 18th August 2020 to © Springer Nature B.V. with all rights reserved.
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Sundström, E., Tomac, M.N. Aeroacoustic Characteristics of a Synchronized Fluidic Oscillator. Flow Turbulence Combust 106, 61–77 (2021). https://doi.org/10.1007/s10494-020-00193-3
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DOI: https://doi.org/10.1007/s10494-020-00193-3