Dependence of High-performance Military Aircraft Noise on Frequency and Engine Power

Leete, Kevin M.; Wall, Alan T.; Gee, Kent L.; Neilsen, Tracianne B.; James, Michael M.; Downing, J. Micah

doi:10.2514/6.2018-2826

Cited by 7 publications

(4 citation statements)

References 34 publications

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“…This combination region extends to approximately 105°, after which the addition of FSS spectrum no longer improves the agreement, and the LSS spectrum matches all except the high frequencies ( Figure 5(b)), which have elevated levels due to nonlinear propagation [48,49]. In the maximum radiation region (inlet angles approximately 110°-140° at 75% ETR), the LSS spectrum captures the overall shape of the peak region of the PSD (Figure 6(a)), but misses several important features: 1) multiple spectral peaks [43,44,45], 2) shallower high-frequency slope (of 1/ K ) resulting from nonlinear propagation [36,37,38,39,48,49], and 3) steeper low-frequency slope. All three features were noted in prior spectral decompositions of high-performance military aircraft [14,15,33], and are discussed in more detail in Sec.…”

Section: Resultsmentioning

confidence: 94%

“…For the one-third octave band analysis of military aircraft engine noise in Ref. [14], only two spectral peaks are evident, but subsequent studies have indicated there are likely more [43,44,45]. More recently, Liu et al [46] has shown a similar separation of different types of propagating waves in numerical simulations of high temperature, supersonic jets.…”

Section: A Similarity Spectra For Turbulent Mixing Noisementioning

confidence: 97%

“…The groundbased linear array provides the opportunity to analyze the spatial variation in F-35B power spectral density (PSD) without interference from ground reflections. These data are used in several concurrent studies, including a correlation and coherence analysis [45] and acoustical holography [44].…”

Section: Measurementmentioning

confidence: 99%

“…[14,33,18,52] for a different aircraft engine and in Refs. [44,45] for the F-35B measurements used in this paper.…”

Section: B Errorsmentioning

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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