Feedback Mechanisms in a Supersonic Impinging Jet using Conditional Proper Orthogonal Decomposition

Stahl, Spencer L.; Prasad, Chitrarth; Gaitonde, Datta V.

doi:10.2514/6.2022-1153

Cited by 1 publication

(1 citation statement)

References 42 publications

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“…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. Cui et al 26 found the oscillation period of the Mach disk and the evolution periods of annular shocks and vortex structures are identical to that of the acoustic wave generations.…”

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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Section: Introduction and State Of The Artmentioning

confidence: 99%