Noise Amplification Effects due to Jet-Surface Interaction

Rego, Leandro F.; Casalino, Damiano; Avallone, Francesco; Ragni, Daniele

doi:10.2514/6.2019-0001

Cited by 7 publications

(2 citation statements)

References 31 publications

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“…6 Rego et al. 7 used Lattice-Boltzmann method to study noise amplification effects due to jet-surface interaction. On the experimental side Head and Fisher 8 and Brown and Ahuja 9 observed that the noise reduction or increase due to interaction with the airframe depends on which radiation side the observer is located.…”

Section: Introductionmentioning

confidence: 99%

A proposed wavy shield for suppression of supersonic jet noise utilizing reflections

Mankbadi

Salehian

2021

International Journal of Aeroacoustics

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In this work we propose replacing the conventional flat-surface airframe that shields the engine by a wavy surface. The basic principle is to design a wavy pattern to reflect the incoming near-field flow and acoustic perturbations into waves of a particular dominant frequency. The reflected waves will then excite the corresponding frequency of the large-scale structure in the initial region of the jet’s shear layer. By designing the frequency of the reflected waves to be the harmonic of the fundamental frequency that corresponds to the radiated peak noise, the two frequency-modes interact nonlinearly. With the appropriate phase difference, the harmonic dampens the fundamental as it extracts energy from it to amplify. The outcome is a reduction in the peak noise. To evaluate this concept, we conducted Detached Eddy Simulations for a rectangular supersonic jet with and without the wavy shield and verified our numerical results with experimental data for a free jet, as well as, for a jet with an adjacent flat surface. Results show that the proposed wavy surface reduces the jet noise as compared to that of the corresponding flat surface by as much as 4 dB.

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Section: Introductionmentioning

confidence: 99%

A proposed wavy shield for suppression of supersonic jet noise utilizing reflections

Mankbadi

Salehian

2021

International Journal of Aeroacoustics

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“…Rego et al [18] utilized a Lattice-Boltzmann Method (LBM) to carry out numerical simulations of a flat plate placed in an irrotational hydrodynamic field of a jet with a round nozzle. Three cases were investigated with input flow characteristics determined from NASA wind tunnel experiments (see Brown [19]).…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of a Rectangular Jet Exhausting over a Flat Plate with Periodic Surface Deformations at the Trailing Edge

et al. 2021

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Multiple competing factors are forcing aircraft designers to reconsider the underwing engine pod configuration typically seen on most modern commercial aircraft. One notable concern is increasing environmental regulations on noise emitted by aircraft. In an attempt to satisfy these constraints while maintaining or improving vehicle performance, engineers have been experimenting with some innovative aircraft designs which place the engines above the wings or embedded in the fuselage. In one configuration, a blended wing concept vehicle utilizes rectangular jet exhaust ports exiting from above the wing ahead of the trailing edge. While intuitively one would think that this design would reduce the noise levels transmitted to the ground due to the shielding provided by the wing, experimental studies have shown that this design can actually increase noise levels due to interactions of the jet exhaust with the aft wing surface and flat trailing edge. In this work, we take another look at this rectangular exhaust port configuration with some notional modifications to the geometry of the trailing edge to determine if the emitted noise levels due to jet interactions can be reduced with respect to a baseline configuration. We consider various horizontal and vertical offsets of the jet exit with respect to a flat plate standing in for the aft wing surface. We then introduce a series of sinusoidal deformations to the trailing edge of the plate of varying amplitude and wave number. Our results show that the emitted sound levels due to the jet–surface interactions can be significantly altered by the proposed geometry modifications. While sound levels remained fairly consistent over many configurations, there were some that showed both increased and decreased sound levels in specific directions. We present results here for the simulated configurations which showed the greatest decrease in overall sound levels with respect to the baseline. These results provide strong indications that such geometry modifications can potentially be tailored to optimize for further reductions in sound levels.

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On the mechanisms of jet-installation noise reduction with flow-permeable trailing edges

Rego

Avallone

Ragni

et al. 2022

Journal of Sound and Vibration

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Noise Amplification Effects due to Jet-Surface Interaction

Cited by 7 publications

References 31 publications

A proposed wavy shield for suppression of supersonic jet noise utilizing reflections

A proposed wavy shield for suppression of supersonic jet noise utilizing reflections

Numerical Investigation of a Rectangular Jet Exhausting over a Flat Plate with Periodic Surface Deformations at the Trailing Edge

On the mechanisms of jet-installation noise reduction with flow-permeable trailing edges

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