On the dominant noise components of tactical aircraft: Laboratory to full scale

Tam, Christopher K. W.; Aubert, Allan C.; Spyropoulos, John T.; Powers, Russell W.

doi:10.1016/j.jsv.2018.02.023

Cited by 26 publications

(17 citation statements)

References 15 publications

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“…II.A. Spectral comparisons have also been shown for a few elevated microphones 38.1 m from a tied-down F-35AA1 [15] and recently for a few ground-based microphones near a tied-down F/A18-A/E [16]. In addition, Harker et al [17,18] explain how the autocorrelation envelopes associated with the similarity spectra agree with the measured autocorrelation near the high-power, installed engine in Ref.…”

Section: Introductionmentioning

confidence: 74%

“…The nature of BBSAN in high-performance military aircraft noise is now under investigation. Tam et al [16] modeled the BBSAN at a few locations near a tied-down F/A-18E operating at afterburner and reported that BBSAN from a high-performance military aircraft agrees with only two of the four trends observed in nonideally expanded, laboratory-scale jets. They indicated that the distinctive BBSAN spectral shape is present and that the spectral peak frequency increases as inlet angle increases for seven locations.…”

Section: Introductionmentioning

confidence: 99%

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Inclusion of Broadband Shock-Associated Noise in Spectral Decomposition of Noise from High-performance Military Aircraft

Neilsen

Vaughn

Gee

et al. 2018

2018 AIAA/CEAS Aeroacoustics Conference

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Attempts to reduce the noise from high-performance military aircraft requires an understanding of the different jet noise generation mechanisms. The primary noise sources originate from interactions between turbulent mixing noise associated with large and finescale turbulent structures and the ambient air. A nonideally expanded jet also contains broadband shock-associated noise. A three-way decomposition of the spectral density measured near a tied-down F-35B quantifies the contribution from each type of noise. The decomposition is performed on noise from a ground-based, linear array of microphones, approximately 8 m from the estimated shear layer, which spanned an angular aperture of 35° to 152° (relative to engine inlet). This large spatial aperture allows for a detailed investigation into the spatial variation in broadband shock-associated noise and fine and large-scale turbulent mixing noise. The spectral decompositions match the measured spectral levels with three main exceptions: 1) the F-35B noise contains multiple spectral peaks in the maximum radiation region, 2) nonlinear propagation increases the high-frequency spectral levels, and 3) the low-frequency levels in the maximum radiation region are less than those predicted by the large-scale similarity spectrum. The main peak of the F-35B broadband shock-associated noise, evident from 35°-70°, has the same characteristic shape and variation in peak frequency as overexpanded, laboratory-scale jets. The F-35B broadband shockassociated noise peak level and width exhibit different trends than laboratory-scale BBSAN and those recently reported for the F/A-18E [

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Section: Introductionmentioning

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Inclusion of Broadband Shock-Associated Noise in Spectral Decomposition of Noise from High-performance Military Aircraft

Neilsen

Vaughn

Gee

et al. 2018

2018 AIAA/CEAS Aeroacoustics Conference

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“…52) and the F-18. 53 At AB in Fig. 2(c), the results are like the MIL spectra, except that the levels are about 4-6 dB higher overall, and the peak level locations are farther upstream, along the array.…”

Section: A Experimentsmentioning

confidence: 63%

Source characterization of full-scale tactical jet noise from phased-array measurements

Harker

Gee

Neilsen

et al. 2019

The Journal of the Acoustical Society of America

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Application of phased-array algorithms to acoustic measurements in the vicinity of a highperformance military aircraft yields equivalent source reconstructions over a range of engine conditions. Beamforming techniques for aeroacoustics applications have undergone significant advances over the past decade to account for difficulties that arise when traditional methods are applied to distributed sources such as those found in jet noise. The hybrid method, an inverse method approached via beamforming, is applied to jet noise measured along a 50 element, 30 m linear array to obtain equivalent source distributions. The source distribution extent decreases with increasing frequency or with a decrease in engine condition. A source coherence analysis along the axial dimension of the jet plume reveals that the source coherence lengths scale inversely with increasing engine condition. In addition, a method for extending the array bandwidth to frequencies beyond the spatial Nyquist frequency limit is also implemented. A directivity analysis of the beamforming results reveals that sources near the nozzle radiate to the sideline from a relatively stationary point irrespective of frequency, while the noise source origin of downstream radiating noise varies significantly with frequency. V

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“…Hence in the upstream direction, the spectrum shows a narrow shock cell noise peak superposing on a broad fine-scale noise spectrum. Measured noise spectra [18] also indicate the possible existence of additional noise components. At this time, however, it is not possible to discern whether they are turbomachinery noise or jet flow-related noise.…”

Section: Military Jets Rockets and Volcanoesmentioning

confidence: 94%

“…Recently, there is a renewed interest in military jet noise (e.g. [16][17][18]). We will test the above question by applying the similarity spectra to the noise of military jets, rockets and volcanoes.…”

Section: Military Jets Rockets and Volcanoesmentioning

confidence: 99%

A phenomenological approach to jet noise: the two-source model

Tam

2019

Phil. Trans. R. Soc. A.

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This is a review of the two-source model of jet noise. The model was developed phenomenologically a number of years ago. One of the principal results associated with this model was the identification of two similarity jet noise spectra. This was accomplished through extensive comparisons with a large set of NASA spectrum data. It was found that these two noise spectra when combined appropriately would fit measured noise spectra of jets in any direction regardless of jet temperature and Mach number. Other experimental data in support of the two-source model have since been found. They are discussed in this paper. One of the purposes of this paper is to elaborate on the flow physics of turbulence, noise generation mechanisms and directivity that are the underpinnings of the model. More recent works show the similarity spectra are applicable, well beyond their original database, to noise of military jets, rockets and even volcanoes. This article is part of the theme issue ‘Frontiers of aeroacoustics research: theory, computation and experiment’.

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On the dominant noise components of tactical aircraft: Laboratory to full scale

Cited by 26 publications

References 15 publications

Inclusion of Broadband Shock-Associated Noise in Spectral Decomposition of Noise from High-performance Military Aircraft

Inclusion of Broadband Shock-Associated Noise in Spectral Decomposition of Noise from High-performance Military Aircraft

Source characterization of full-scale tactical jet noise from phased-array measurements

A phenomenological approach to jet noise: the two-source model

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