Experimental investigation of nonlinear properties of crackle and screech in supersonic jets

Punekar, J.; Avital, Eldad; Li, X.

doi:10.1121/1.4985585

Cited by 5 publications

(3 citation statements)

References 14 publications

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“…5 reported at 80 • a progressive reduction in the screech tone amplitude with increasing nozzle pressure ratio. This suggests that the observed high skewness level at 80°is related to the amplitude of the screech tone, specifically it is thought that the large amplitude pressure waves associated to screech may generate a non-linear sound propagation with significant skewness [4].…”

Section: Skewness Of Acoustic Pressure Fluctuationmentioning

confidence: 99%

“…Crackle accounts for approximately 30% of the total annoyance of jet noise. Punekar et al [3,4], at the Queen Mary University of London (QMUL) model jet facility, used contoured nozzles of design Mach number M d = 1.3 and 2 to show that crackle is present at shallow polar angles from the jet axis. This radiation direction was characterized by a high skewness of the acoustic pressure.…”

Section: Introductionmentioning

confidence: 99%

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Skewness as means for separating crackle from screech

Punekar

Avital

Rona

2019

25th AIAA/CEAS Aeroacoustics Conference

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Screech and crackle are investigated by far-field acoustic measurements and visualizations of a cold jet from a Mach 2 convergent-divergent nozzle operated over-expanded, fully expanded, and under-expanded. The skewness of the sampled far-field pressure frequency distribution is evaluated at polar angles below 90°. It is found that skewness alone is insufficient for singling out crackling noise, however, a better characterization is obtained by jointly considering the skewness of the acoustic pressure time derivative. New evidence is provided of crackle and screech being competitive mechanisms over the nozzle pressure ratio range 4.3 to 10. These new physical insights advance the current understanding of high-speed jet aeroacoustics, towards enabling sustainable airport operations of supersonic civil aircraft.

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Section: Skewness Of Acoustic Pressure Fluctuationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Skewness as means for separating crackle from screech

Punekar

Avital

Rona

2019

25th AIAA/CEAS Aeroacoustics Conference

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“…In particular, the jet noise becomes more severe in the supersonic regime with additional complicated elements, such as screech tones and broadband shock-associated noise [1]. Crackle is another shock-related component that induces an irritating noise by nonlinear propagation [2,3]. In addition to noise pollution, intense acoustic loads from the jet noise will induce failures [4], such as the malfunction of vehicle electronic devices and fatigue failure of the internal/external structures.…”

Section: Introductionmentioning

confidence: 99%

Acoustic measurement of under-expanded jet and its numerical prediction

et al. 2022

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Intense acoustic loads from jet noise cause noise pollution and induce failures, such as the malfunctioning of electronic devices and fatigue failure of internal/external structures. Consequently, the prediction of jet noise characteristics is crucial in the development of high-speed vehicles. This study presents acoustic experiments and predictions for an under-expanded, unheated jet using a small-scale prototype. Outdoor measurements are carried out using a vertical ejection setup. Acoustic characteristics are measured using both linear and circular microphone arrays. Additionally, numerical prediction of the same jet noise is performed using a detached eddy simulation and the permeable Ffowcs-Williams and Hawkings acoustic analogy. The vertical experimental setup exhibits the typical acoustic characteristics of a supersonic jet in terms of directivity and broadband shock-associated noise. Moreover, the numerical prediction exhibits satisfactory accuracy for the jet downstream, where the large-scale turbulence structures of the directivity predominate. However, discrepancy increases in the domain of lower directivity. The presented experiment and prediction will be extended to future studies regarding the noise of various deflector duct configurations impinging on supersonic jets.

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Aeroacoustics research in Europe: The CEAS-ASC report on 2017 highlights

Enghardt

2019

Journal of Sound and Vibration

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The prediction of the high Reynolds number turbulent boundary layer wall pressure spectrum is important for the estimation and reduction of its impact on aircraft cabin noise level. Flat plate turbulent boundary layers are simulated using synthetic anisotropic turbulence generated by the fast random particle-mesh method [1] [2]. The anisotropy is taken into account in two different stages. The first one considers the one-point statistics of the Reynolds stress tensor and the second additionally realizes anisotropic turbulence length scales. The impact of the turbulence structure on the resulting wall pressure spectra is studied.

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Experimental investigation of nonlinear properties of crackle and screech in supersonic jets

Cited by 5 publications

References 14 publications

Skewness as means for separating crackle from screech

Skewness as means for separating crackle from screech

Acoustic measurement of under-expanded jet and its numerical prediction

Aeroacoustics research in Europe: The CEAS-ASC report on 2017 highlights

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