Jet Noise in Airframe Integration and Shielding

Salehian, Saman; Mankbadi, Reda R.

doi:10.3390/app10020511

Cited by 18 publications

(3 citation statements)

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“…Sensitivity studies of the extent of the FWH up to x/D=40 is investigated previously and reported by Salehian and Mankbadi. 1 Such grid spacing on FWH surface would ensure capturing acoustic waves up to Strouhal number St=fD/Uj=0.35−0.4 where f is the frequency. This maximum frequency represents up to 75% of the spectra (in logarithmic scale) shown in experimental results and contains most of the trend in spectral analysis of the acoustic signal, such as the peak frequency of St=0.1 observed in experimental results.…”

Section: Numerical Approachmentioning

confidence: 99%

“…This is generally referred to as the installation noise or interaction effect. A detailed review on jet-surface interaction and shielding effect on jet noise is provided by Salehian and Mankbadi 1 The focus here is on the case where there is some distance between the jet plume and the airframe surface/wing. In several pursued aircraft design configuration concepts, the engine is mounted on top.…”

Section: Introductionmentioning

confidence: 99%

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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: Numerical Approachmentioning

confidence: 99%

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 the same way, the wall pressure load generated by the external turbulent boundary layer and by the impact of the jet plume over the rear part of the fuselage or on the wing pressure side can cause fatigue problems because of the induced vibrations. Above all, in future configurations, like the blended wing body where the fuselage efficiently shields the jet noise, the jet-induced wall pressure load could significantly stress the aircraft panels (Liebeck 2002; Salehian & Mankbadi 2020).…”

Section: Introductionmentioning

confidence: 99%

Experimental characterisation and data-driven modelling of unsteady wall pressure fields induced by a supersonic jet over a tangential flat plate

Meloni

Centracchio²,

Paola³

et al. 2023

J. Fluid Mech.

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This work deals with the investigation and modelling of wall pressure fluctuations induced by a supersonic jet over a tangential flat plate. The analysis is performed at several nozzle pressure ratios around the nozzle design Mach number, including slightly over-expanded and under-expanded conditions, and for different radial positions of the rigid plate. Pitot measurements and flow visualizations through the background oriented schlieren technique provided a general overview of the aerodynamic interactions between the jet flow and the plate at the different regimes and configurations. Wall pressure fluctuations were measured using a couple of piezoelectric pressure transducers flush mounted over the plate surface. The spectral analysis has been carried out to clarify the effect of the plate position on the single and multivariate wall pressure statistics, including the screech tone amplitude. The experimental dataset is used to assess and validate a surrogate model based on artificial neural networks. Sound pressure levels and coherence functions are modelled by means of a single fully connected network, built on the basis of a recently implemented fully deterministic topology optimization algorithm. The metamodel uncertainty is also quantified using the spatial correlation function. It is shown that the flow behaviour as well as the screech and broadband noise signatures are significantly influenced by the presence of the plate, and the effects on spectral quantities are correctly reproduced by the proposed data-driven model that provides predictions in agreement with the available data.

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