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Large-eddy simulations of flow and aeroacoustics of twin square jets including turbulence tripping
KTH, School of Engineering Sciences (SCI), Engineering Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.ORCID iD: 0000-0002-9054-8832
KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.ORCID iD: 0000-0001-7330-6965
University of Cincinnati.
Aerospace Engineering, University of Cincinnati.
2023 (English)In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 35, no 6Article in journal (Refereed) Published
Abstract [en]

In this study, we investigate the flow and aeroacoustics of twin square (i.e., aspect ratio of 1.0) jets by implicit large-eddy simulations (LESs) under a nozzle pressure ratio of 3.0 and a temperature ratio of 1.0 conditions. A second-order central scheme coupled with a modified Jameson's artificial dissipation is used to resolve acoustics as well as to capture discontinuous solutions, e.g., shock waves. The flow boundary layer inside of the nozzle is tripped, using a small step in the convergent section of the nozzle. The time-averaged axial velocity and turbulent kinetic energy of LES with boundary layer tripping approaches better to particle image velocimetry experimental data than the LES without turbulence tripping case. A two-point space–time cross-correlation analysis suggests that the twin jets are screeching and are coupled to each other in a symmetrical flapping mode. Intense pressure fluctuations and standing waves are observed between the jets. Spectral proper orthogonal decomposition (SPOD) confirms the determined mode and the relevant wave propagation. The upstream propagating mode associated with the shock-cell structures is confined inside jets. Far-field noise obtained by solving Ffowcs Williams and Hawkings equation is in good agreement with the measured acoustic data. The symmetrical flapping mode of twin jets yields different levels of the screech tone depending on observation planes. The tonalities—the fundamental tone, second and third harmonics—appear clearly in the far-field, showing different contributions at angles corresponding to the directivities revealed by SPOD.

Place, publisher, year, edition, pages
AIP Publishing , 2023. Vol. 35, no 6
Keywords [en]
Large-eddy simulations; supersonic jets; aeroacoustics; twin square jets; turbulence tripping
National Category
Fluid Mechanics and Acoustics Aerospace Engineering
Research subject
Engineering Mechanics; Aerospace Engineering
Identifiers
URN: urn:nbn:se:kth:diva-328170DOI: 10.1063/5.0147295ISI: 001000311200006Scopus ID: 2-s2.0-85161003914OAI: oai:DiVA.org:kth-328170DiVA, id: diva2:1762293
Note

QC 20230630

Available from: 2023-06-02 Created: 2023-06-02 Last updated: 2023-06-30Bibliographically approved

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Publisher's full textScopushttps://doi.org/10.1063/5.0147295

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Ahn, MyeongHwanMihaescu, Mihai

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