Landing Gear Noise Sources Identification through an Application of Array Methods to Experimental and Computational Data

Redonnet, Stephane; Bulté, Jean

doi:10.2514/6.2016-2844

Cited by 7 publications

(8 citation statements)

References 14 publications

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“…For the sake of conciseness, the section below summarizes only a fraction of these noise source localization efforts [29], focusing in particular on the sole baseline CFD-CAA computation (i.e. as-like F2 experiment).…”

Section: Further Investigation About the Nlg Noise Sourcesmentioning

confidence: 99%

“…This work, which was achieved by the present first and fourth authors, is detailed in Section 4. Finally, based on the CFD-CAA numerical signals acquired over dedicated microphone arrays, the NLG noise sources were further characterized through the use of advanced signal processing techniques [29]; more precisely, once acquired over virtual microphone arrays matching those used in the experiments, the CFD-CAA signals were processed following two distinct array methods of source localization, namely Classical Beam Forming (CBF) and Deconvolution Approach for the Mapping of Acoustic Sources (DAMAS). Such work, which was primarily achieved by the present third and first authors, was documented through the 22th AIAA Aeroacoustics Conference [29], and is recalled in Section 5.…”

Section: Introductionmentioning

confidence: 99%

“…Finally, based on the CFD-CAA numerical signals acquired over dedicated microphone arrays, the NLG noise sources were further characterized through the use of advanced signal processing techniques [29]; more precisely, once acquired over virtual microphone arrays matching those used in the experiments, the CFD-CAA signals were processed following two distinct array methods of source localization, namely Classical Beam Forming (CBF) and Deconvolution Approach for the Mapping of Acoustic Sources (DAMAS). Such work, which was primarily achieved by the present third and first authors, was documented through the 22th AIAA Aeroacoustics Conference [29], and is recalled in Section 5. Again, in the wake of the latter effort, and upon the proposal of the present first and third authors, lately, a benchmark test case was incorporated within the so-called Array Method workshop, which is an international initiative 4 that seeks at improving the signal processing techniques commonly employed worldwide for identifying aircraft noise sources.…”

Section: Introductionmentioning

confidence: 99%

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Numerical characterization of landing gear aeroacoustics using advanced simulation and analysis techniques

Redonnet

Khelil

Bulté

et al. 2017

Journal of Sound and Vibration

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With the objective of aircraft noise mitigation, we here address the numerical characterization of the aeroacoustics by a simplified nose landing gear (NLG), through the use of advanced simulation and signal processing techniques. To this end, the NLG noise physics is first simulated through an advanced hybrid approach, which relies on Computational Fluid Dynamics (CFD) and Computational AeroAcoustics (CAA) calculations. Compared to more traditional hybrid methods (e.g. those relying on the use of an Acoustic Analogy), and although it is used here with some approximations made (e.g. design of the CFD-CAA interface), the present approach does not rely on restrictive assumptions (e.g. equivalent noise source, homogeneous propagation medium), which allows to incorporate more realism into the prediction. In a second step, the outputs coming from such CFD-CAA hybrid calculations are processed through both traditional and advanced post-processing techniques, thus offering to further investigate the NLG's noise source mechanisms. Among other things, this work highlights how advanced computational methodologies are now mature enough to not only simulate realistic problems of airframe noise emission, but also to investigate their underlying physics.

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Section: Further Investigation About the Nlg Noise Sourcesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Numerical characterization of landing gear aeroacoustics using advanced simulation and analysis techniques

Redonnet

Khelil

Bulté

et al. 2017

Journal of Sound and Vibration

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“…In other studies the phased array is located farther from the sources and the acoustic data has to be extrapolated from the flow solution. This extrapolation is most often performed using integral methods such as the Ffowcs Williams-Hawkings (FW-H) integral [12,13,14,15,16,17], but other approaches can be found [18]. Extrapolation is performed when the acoustic field is not expected to be sufficiently well-resolved at the location of the array.…”

Section: Introductionmentioning

confidence: 99%

Identifying equivalent sound sources from aeroacoustic simulations using a numerical phased array

Pignier

O’Reilly

Boij

2017

Journal of Sound and Vibration

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PostprintThis is the accepted version of a paper published in Journal of Sound and Vibration. This paper has been peer-reviewed but does not include the final publisher proof-corrections or journal pagination.Citation for the original published paper (version of record):Pignier, N., O'Reilly, C J., Boij, S. (2017) Identifying equivalent sound sources from aeroacoustic simulations using a numerical phased array. Journal of Sound and Vibration AbstractAn application of phased array methods to numerical data is presented, aimed at identifying equivalent flow sound sources from aeroacoustic simulations. Based on phased array data extracted from compressible flow simulations, sound source strengths are computed on a set of points in the source region using phased array techniques assuming monopole propagation. Two phased array techniques are used to compute the source strengths: an approach using a Moore-Penrose pseudo-inverse and a beamforming approach using dual linear programming (dual-LP) deconvolution. The first approach gives a model of correlated sources for the acoustic field generated from the flow expressed in a matrix of cross-and auto-power spectral values, whereas the second approach results in a model of uncorrelated sources expressed in a vector of auto-power spectral values. The accuracy of the equivalent source model is estimated by computing the acoustic spectrum at a far-field observer. The approach is tested first on an analytical case with known point sources. It is then applied to the example of the flow around a submerged air inlet. The far-field spectra obtained from the source models for two different flow conditions are in good agreement with the spectra obtained with a Ffowcs Williams-Hawkings integral, showing the accuracy of the source model from the observer's standpoint. Various configurations for the phased array and for the sources are used. The dual-LP beamforming approach shows better robustness to changes in the number of probes and sources than the pseudo-inverse approach. The good results obtained with this simulation case demonstrate the potential of the phased array approach as a modelling tool for aeroacoustic simulations.

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“…On the other hand, extensive wind-tunnel or flyover test campaigns usually have a large economic cost, limiting the amount of configurations available to study. In practice, for numerical simulations, the geometry of the LG is normally simplified to some extent where the computational cost is acceptable, such as the realistic NLG geometry from the ALLEGRA project [27][28][29] or the more simplified LAGooN geometry from ONERA [30]. One advantage of computational simulations is that they allow for non-intrusive measurements in directions that are impossible to investigate in experiments (such as upwind of the model) and that the acoustic data are usually cleaner than those recorded in experiments, allowing for shorter recording times.…”

mentioning

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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Landing Gear Noise Sources Identification through an Application of Array Methods to Experimental and Computational Data

Cited by 7 publications

References 14 publications

Numerical characterization of landing gear aeroacoustics using advanced simulation and analysis techniques

Numerical characterization of landing gear aeroacoustics using advanced simulation and analysis techniques

Identifying equivalent sound sources from aeroacoustic simulations using a numerical phased array

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

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