The application of advanced beamforming techniques for the noise characterization of installed counter rotating open rotors

Kennedy, John; Eret, Petr; Bennett, Gareth J.; Castellini, Paolo; Chiariotti, Paolo; Sopranzetti, Francesca; Picard, Christophe; Finez, Arthur

doi:10.2514/6.2013-2093

Cited by 11 publications

(15 citation statements)

References 5 publications

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“…The beamforming results were normalized by the integrated array response for a point source in the center of the integration area, also known as Point Spread Function (PSF). This way, more physical results are obtained, not conditioned by the assumption that only point sources are present [24,[29][30][31][32].…”

Section: Iiia Methods For the Wind-tunnel Experimentsmentioning

confidence: 99%

Comparing flyover noise measurements to full-scale nose landing gear wind tunnel experiments for regional aircraft

Martinez

Neri

Snellen

et al. 2017

23rd AIAA/CEAS Aeroacoustics Conference

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The noise emissions of the nose landing gear of a full-scale model tested in a wind tunnel, and of three regional aircraft types in flyover measurements are compared in this contribution. The geometries of the nose landing gears in all cases were similar. Microphone arrays and beamforming algorithms were used to determine the sound emissions of the nose landing gears. A good agreement was found between the overall trends of the frequency spectra in all cases. Moreover, the expected 6 th power law with the flow velocity was confirmed for both experiments. On the other hand, strong tonal peaks (at around 2200 Hz) were only found for the flyover tests. As the frequencies of the tones do not depend on the aircraft velocity, they are thought to be caused by cavities found in structural components of the nose landing gear. Removing these tones would cause overall noise reductions up to 2 dB in the frequency range examined. It is, therefore, recommended to further investigate this phenomenon, to include cavity-noise estimations in the current noise prediction models, and to eliminate such cavities where possible.

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Section: Iiia Methods For the Wind-tunnel Experimentsmentioning

confidence: 99%

Comparing flyover noise measurements to full-scale nose landing gear wind tunnel experiments for regional aircraft

Martinez

Neri

Snellen

et al. 2017

23rd AIAA/CEAS Aeroacoustics Conference

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“…Funke et al [10] have processed a series of linear array data using a novel inverse method in order to investigate the directivities of broadband noise sources, while localizing tonal noise sources to given axial positions using phased array microphone technology. Kennedy et al [17] and Chiariotti et al [16] have used multiple phased arrays in the beamforming investigation of various 1/7 th scale model aircraft configurations. These results do not present a detailed description of the source distributions, but rather investigate the effects of the various aircraft configurations.…”

Section: Introductionmentioning

confidence: 99%

“…Many investigations have used measurement as well as simulation data in order to investigate CROR engines equipped with pylons. Most of these investigations have focused on the noise generation of the aircraft as a whole, examining the directivity of noise radiating from the aircraft using linear and planar arrays of microphones [16][17][18][19][20]. Another set of investigations have focused on the engine, with some examining only those configurations which were equipped with a pylon [12], while others have looked at only an uninstalled case [13][14][15][21][22][23], but few have compared the two [9,24], with none of the investigations focusing on localizing the noise sources, separating them into groups of tonal and broadband noise sources, and comparing these groups for the two cases.…”

Section: Introductionmentioning

confidence: 99%

Investigation of a Pylons Effect on the Character of Counter-Rotating Open Rotor Noise Using Beamforming Technology

Fenyvesi¹,

Tokaji²,

Horváth³

2019

Acta Acustica united with Acustica

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Phased array microphones and beamforming technology are applied herein in order to better understand the noise sources associated with the installation effects of a counter-rotating open rotor propulsion system. The study compares an installed (equipped with a pylon) and an uninstalled (standalone) engine for takeoff nominal flight conditions, using beamforming results to investigate the far-field acoustic character and to localize noise sources, sorting them into various components accordingly. The study demonstrates how the various noise sources falling in the blade passing frequency bins can be separated into those components which are truly associated with the blade passing frequency and those which are associated with blade-wake interactions. This is done by taking into consideration the nature of the noise sources, and distinguishing between rotating coherent and stationary coherent noise sources. The paper also demonstrates that the impact of the pylon wake on the rotating coherent noise sources (such as blade passing frequency tones and interaction tones) and on the rotating incoherent noise sources (such as rotating broadband noise sources and shaft order noise sources) is small. Though the paper presents the results of a specific comparison, the methodology for separating apart the various components noise presented herein is generally applicable in other investigations.

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“…The beamforming results were normalized by the integrated array response for a point source in the center of the ROI, also known as Point Spread Function (PSF). This way, more physical results are obtained, because the influence of the PSF in the results of the array is reduced [39,[51][52][53][54][55]. In addition, the high-resolution deconvolution method HR-CLEAN-SC [56][57][58] was also applied to the data from both arrays in order to obtain a better dynamic range (less and lower sidelobes) and to investigate whether one or more sound sources were present (even within Rayleigh resolution limit [56][57][58]).…”

Section: Iiia Methods For the Wind-tunnel Experimentsmentioning

confidence: 99%

Analysis of nose landing gear noise comparing numerical computations, prediction models and flyover and wind-tunnel measurements

Martinez

Neri

Snellen

et al. 2018

2018 AIAA/CEAS Aeroacoustics Conference

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The noise emissions of a full-scale nose landing gear, measured in a wind tunnel and obtained from computational simulations, are compared with those of three regional aircraft types recorded in flyover measurements. The results from these three approaches are also compared with the predictions of two airframe noise models (Fink and Guo). The geometries of the nose landing gears in all cases were similar. Microphone arrays and acoustic imaging algorithms were employed to estimate the sound emissions of the nose landing gears. A good agreement was found between the overall trends of the frequency spectra in all cases. Moreover, the expected 6 th power law with the flow velocity was confirmed. On the other hand, strong tonal peaks (at around 2200 Hz) were only found for the flyover tests and computational simulations and are not present in typical noise prediction models. As the frequencies of the tones did not depend on the flow velocity, they are likely to be caused by cavities found in structural components of the nose landing gear. Removing these tones would cause overall noise reductions up to 2 dB in the frequency range examined. The noise emissions in the side direction did not present tonal peaks. The acoustic source maps showed that the dominant noise sources were located in the middle of the wheel axle, followed by the main strut and the bay doors. It is, therefore, recommended to further investigate this phenomenon, to include cavity-noise estimations in the current noise prediction models, and to eliminate such cavities where possible with the use of cavity caps, for example.

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The application of advanced beamforming techniques for the noise characterization of installed counter rotating open rotors

Cited by 11 publications

References 5 publications

Comparing flyover noise measurements to full-scale nose landing gear wind tunnel experiments for regional aircraft

Comparing flyover noise measurements to full-scale nose landing gear wind tunnel experiments for regional aircraft

Investigation of a Pylons Effect on the Character of Counter-Rotating Open Rotor Noise Using Beamforming Technology

Analysis of nose landing gear noise comparing numerical computations, prediction models and flyover and wind-tunnel measurements

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