Spectral proper orthogonal decomposition of coupled hydrodynamic and acoustic fields: Application to impinging jet configurations (draft)

Fiore, Maxime; Parisot-Dupuis, Hélène; Etchebarne, B.; Gojon, Romain

doi:10.1016/j.compfluid.2022.105484

Cited by 6 publications

(3 citation statements)

References 42 publications

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“…A frequency-wavenumber filtering procedure used to isolate the aerodynamic fluctuations and estimate their nozzle-to-plate gains in amplitude is described in Appendix B. Finally, a spectral proper orthogonal decomposition Fiore et al 2022) applied to extract the resonant modes of the Mach number 0.6 jets from the full LES signals is presented in Appendix C.…”

Section: Introductionmentioning

confidence: 99%

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Influence of the boundary-layer thickness on the generation of tonal noise components by subsonic impinging jets

Vincent,

Bogey

2024

J. Fluid Mech.

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The influence of the boundary layer (BL) thickness on the tonal noise generated by subsonic impinging jets is investigated. For that, initially laminar jets at Mach numbers $0.6$ and $0.9$ with BL thicknesses $0.05r_0$ , $0.1r_0$ and $0.2r_0$ , where $r_0$ is the pipe-nozzle radius, impinging on a plate at $6r_0$ from the nozzle, are simulated. For Mach number $0.9$ , acoustic tones due to feedback loops of axisymmetric nature between the nozzle and the plate are generated at frequencies that do not vary with the BL thickness. The two dominant tones are, however, $17$ and $26\ \mathrm {dB}$ stronger for the thickest BL compared with the thinnest one. For Mach number $0.6$ , for the thinnest BL no acoustic peaks appear, as observed in the experiments of the literature, but narrow peaks resulting from axisymmetric feedback loops emerge for thicker BLs. Therefore, low subsonic impinging jets can be resonant for specific nozzle-exit conditions. The increase in tone amplitude for Mach number $0.9$ , and the establishment of feedback loops for Mach number $0.6$ with increasing BL thickness, are found to result from two changes in the jet flow. The first change is that the shear-layer laminar–turbulent transition occurs farther downstream for a thicker BL, leading to a greater predominance of the axisymmetric aerodynamic fluctuations near the plate. The second change is that the amplification of the flow fluctuations between the nozzle and the plate at the tone frequencies is stronger for thicker BLs.

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Section: Introductionmentioning

confidence: 99%

“…Finally, a spectral proper orthogonal decomposition (Towne, Schmidt & Colonius 2018; Fiore et al. 2022) applied to extract the resonant modes of the Mach number jets from the full LES signals is presented in Appendix C.…”

Section: Introductionmentioning

confidence: 99%

Influence of the boundary-layer thickness on the generation of tonal noise components by subsonic impinging jets

Vincent,

Bogey

2024

J. Fluid Mech.

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“…Their results showed that angles greater than 80° from the jet axis demonstrated the highest receptivity, except for azimuthal mode number 2 in the case of a nozzle-to-wall distance of 5d. Fiore et al 24 applied spectral proper orthogonal decomposition to large-eddy simulations of supersonic impinging planar jets, the framework captures crucial aero-acoustic feedback loops and correlates symmetrical/anti-symmetrical acoustic patterns to axial or vertical velocity fluctuations in the jet, depending on impingement and incidence angle. Similarly, Stahl et al 25 applied conditional proper orthogonal decomposition to the Large Eddy Simulation of an impinging jet, revealing a correlation between the behavior of the receptivity modes and the arrival of acoustic feedback waves outside the jet, as well as a delayed feedback arrival inside the jet.…”

Section: Introduction and State Of The Artmentioning

confidence: 99%

Acoustic characteristics of jets impinging on permeable plates

Dhamanekar,

Srinivasan

2023

International Journal of Aeroacoustics

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This article explores the acoustic characteristics and the relevant flow features of jets impinging on permeable plates. Noise generated due to the interaction of the jet with permeable plates is compared with jets impinging on an impermeable plate and the corresponding free jet. This study systematically measures various parameters, including pore size, porosity, and pressure drop, to precisely quantify the permeability of the plates using the Forchheimer equation. The focus is on investigating the impact of permeability on noise reduction. An acoustic study is performed by carrying out blow-up and blow-down tests to find the effect of permeability at different nozzle pressure ratios and different nozzle-plate spacings. An extensive directivity study is conducted to find the directionality of acoustic emissions and calculate acoustic power. It is found that the overall sound pressure level is lower for the jets impinging on the permeable plates compared to the impermeable plates in subsonic cases. It is also observed that the insertion of the permeable plates in supersonic jets generates less noise compared to the corresponding free jet. It is found that most of the tones are absent in the case of permeable plates for supersonic jets, whereas the tones are present with lesser amplitude compared to jets impinging on impermeable plates for subsonic and transonic jets. Finally, flow measurement and flow visualization studies are carried out to understand the flow physics responsible for the noise variance. This study illuminates that the passage of flow through the porous plate results in the reduction of wall-jet velocities, thereby suppressing the turbulent mixing noise. The absence of shock oscillations in front of the permeable plate is identified as the cause of the mitigation of impinging tones.

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The interaction between turbulent separation bubble breathing and wall pressure on a 2D wing

Wang,

Gibeau,

Ghaemi

2024

Exp Fluids

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Spectral proper orthogonal decomposition of coupled hydrodynamic and acoustic fields: Application to impinging jet configurations (draft)

Cited by 6 publications

References 42 publications

Influence of the boundary-layer thickness on the generation of tonal noise components by subsonic impinging jets

Influence of the boundary-layer thickness on the generation of tonal noise components by subsonic impinging jets

Acoustic characteristics of jets impinging on permeable plates

The interaction between turbulent separation bubble breathing and wall pressure on a 2D wing

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