Airframe Noise Source Locations of a 777 Aircraft in Flight and Comparisons with Past Model-Scale Tests

Stoker, Robert W.; Guo, Yueping; Streett, Craig L.; Burnside, Nathan

doi:10.2514/6.2003-3232

Cited by 69 publications

(46 citation statements)

References 6 publications

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“…Wind tunnel tests [1][2][3] and fl y-over measurements 4 have revealed the leading-edge slats, fl ap edges, and the landing gear to be the major contributors to airframe noise. Each of the three primary sources of airframe noise are important on different classes of airplanes, but the main landing gear is a dominant source on most modern wide-body transports.…”

Section: Aiaa-2004-2887mentioning

confidence: 99%

Aeroacoustic Analysis of a Simplified Landing Gear

Lockard

Khorrami

2003

9th AIAA/CEAS Aeroacoustics Conference and Exhibit

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A hybrid approach is used to investigate the noise generated by a simplified landing gear without small scale parts such as hydraulic lines and fasteners. The Ffowcs Williams and Hawkings equation is used to predict the noise at far-field observer locations from flow data provided by an unsteady computational fluid dynamics calculation. A simulation with 13 million grid points has been completed, and comparisons are made between calculations with different turbulence models. Results indicate that the turbulence model has a profound effect on the levels and character of the unsteadiness. Flow data on solid surfaces and a set of permeable surfaces surrounding the gear have been collected. Noise predictions using the porous surfaces appear to be contaminated by errors caused by large wake fluctuations passing through the surfaces. However, comparisons between predictions using the solid surfaces with the near-field CFD solution are in good agreement giving confidence in the far-field results.

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Section: Aiaa-2004-2887mentioning

confidence: 99%

Aeroacoustic Analysis of a Simplified Landing Gear

Lockard

Khorrami

2003

9th AIAA/CEAS Aeroacoustics Conference and Exhibit

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“…On the other hand, field experiments with aircraft flyovers under operational conditions present different challenges, such as the inability to control the aircraft position, larger distances between the sound source and the observer, and less-controlled flow characteristics, but they fully represent the actual conditions experienced in reality [18,19], such as crosswind. Differences between both kinds of experiments typically occur, mostly due to lack of model fidelity, installation effects in the wind tunnel and discrepancies in the Reynolds number [20]. Hence, a comparison between the results of flyover and wind-tunnel measurements is of great interest [13].…”

Section: Introductionmentioning

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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“…Along with high-lift devices, the landing gear of aircraft are known to be an important source of noise during approach conditions 1,2 . However, the complexity of the landing gear geometry and the resulting unsteady flow field in the vicinity of the gear poses severe challenges to the development and application of physics based models for landing gear noise.…”

Section: Introductionmentioning

confidence: 99%