Laminar and turbulent shear flow induced cavity resonances

DeMetz, Fred C.; Farabee, Theodore M.

doi:10.2514/6.1977-1293

Cited by 45 publications

(27 citation statements)

References 5 publications

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“…Therefore, the noise levels of both LG systems usually have comparable values [9]. A typical sound signal from a LG system is a combination of broadband noise, mainly caused by the interaction of the LG with the turbulent flow, and tonal noise, generated by noise due to cavities [10,11] and Aeolian tones due to flow separation and vortex shedding [12,13]. The frequency of the tone due to a cavity mainly depends on the cavity geometry itself [10], whereas for Aeolian tones, the tone frequency also depends on the flow velocity.…”

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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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 reason why the noise from the front bogie section of the lead car is larger than that from other bogie sections is: (1) The wind velocity is larger compared with that at leeward bogie sections. (2) The flow that comes to the section is laminar and the instability of shear layer grows to cause large pressure fluctuations 3) . The tones of discrete frequencies at the inter-car gaps are generated by the resonance at deep cavities.…”

Section: Computational Results Computational Results Computational Rementioning

confidence: 99%

Study on the Aeroacoustic Noise from Shinkansen with Mirror Image Models

Takaishi¹,

Zenda²,

Shimizu

2001

QR of RTRI

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“…They include a jet through a system of orifice plates (Hourigan et al, 1990;Stoubos et al 1999), a separated shear layer past a cavity resonator (DeMetz & Farabee, 1977;Elder, 1978;Elder, Farabee & DeMetz, 1982;andNelson et al 1981, 1983), and a separated layer past a resonant side branch in the form of a duct or pipe (Pollack, 1980;Bruggeman et al 1989Bruggeman et al , 1991Kreisels ef al. 1995;Ziada & Biihlmann, 1992;and Ziada & Shine, 1999).…”

Section: Overview Of Flow Tonesmentioning

confidence: 99%

Imaging of the Self-Excited Oscillation of Flow Past a Cavity During Generation of a Flow Tone

Geveci

Oshkai

Rockwell

et al. 2002

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Flow through a pipeline-cavity system can give rise to pronounced ff ow tones, even when the inflow boundary layer is fully turbulent. Such tones arise from the coupling between the inherent instability of the shear flow past the cavity and a resonant acoustic mode of the system. A technique of high-image-density particle image velocimetry is employed in conjunction with a special test section, which allows effective laser illumination and digital acquisition of patterns of particle images. This approach leads to patterns of velocity, vorticity, streamline topology and hydrodynamic contributions to the acoustic power integral. Comparison of global, instantaneous images with time-and phaseaveraged representations provides insight into the small-scale and large-scale concentrations of vorticity, and their consequences on the topological features of Streamline patterns, as well as the streamwise and transverse projections of the hydrodynamic contribution to the acoustic power integral. Furthermore, these global approaches allow the definition of effective wavelengths and phase speeds of the vortical structures, which can lead to guidance for physical models of the dimensionless frequency of oscillation.

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Laminar and turbulent shear flow induced cavity resonances

Cited by 45 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

Study on the Aeroacoustic Noise from Shinkansen with Mirror Image Models

Imaging of the Self-Excited Oscillation of Flow Past a Cavity During Generation of a Flow Tone

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