Broadband and discrete frequency radiation from subsonic rotors

Homicz, Gregory F.; George, A. R.

doi:10.1016/s0022-460x(74)80292-0

Cited by 87 publications

(26 citation statements)

References 21 publications

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“…The effect of U /A 2 on the spectrum is the same as that 3,i 3 iõ btained by Homicz [8]. However, the effect of RT/Ai on the spectrum for constant U /Ai ' is the opposite of that claimed by Mani [15].…”

Section: Uc(s) Ssupporting

confidence: 56%

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Rotor noise due to blade turbulence interaction

Ishimaru¹

1984

The Journal of the Acoustical Society of America

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Section: Uc(s) Ssupporting

confidence: 56%

“…Homicz [8], Gutin (9], Wright [10,11], and others pursued the on-off dipole model. On the other hand, the on-off model does not account for it because the distance between the on-off dipole and the observer is fixed all the time.…”

Section: Previous Investioations Of Rotor Noisementioning

confidence: 99%

Rotor noise due to blade turbulence interaction

Ishimaru¹

1984

The Journal of the Acoustical Society of America

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“…Turbulence ingestion noise, airfoil self noise, tip-vortex noise, and other broadband noise sources have typically been treated through empirical or semi-empirical methods. [2][3][4][5][6] In addition, the acceptance of wind turbines by the public depends strongly on achieving low noise levels in application.…”

Section: Introductionmentioning

confidence: 99%

3-D Time-Accurate CFD Simulations of Wind Turbine Rotor Flow Fields

Sezer-Uzol

Long

2006

44th AIAA Aerospace Sciences Meeting and Exhibit

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This paper presents the results of three-dimensional and time-accurate Computational Fluid Dynamics (CFD) simulations of the flow field around the National Renewable Energy Laboratory (NREL) Phase VI horizontal axis wind turbine rotor. The 3-D, unsteady, parallel, finite volume flow solver, PUMA2, is used for the simulations. The solutions are obtained using unstructured moving grids rotating with the turbine blades. Three different flow cases with different wind speeds and wind yaw angles are investigated: 7 m/s with 0 • yaw (pre-stall case I), 7 m/s with 30 • yaw (prestall, yawed case II), and 15 m/s with 0 • yaw (post-stall case III). Results from the inviscid simulations for these three cases and comparisons with the experimental data are presented. Some information on the current work in progress towards Large Eddy Simulations (LES), including details about the viscous grid and the implementation of wall-functions, are also discussed. The inviscid results show that the flow is attached for cases I and II, with the latter having an asymmetrical wake structure, whereas there is massive separation over the entire blade span in case III. There are considerable spanwise pressure variations in addition to the chordwise variations, in all three cases. Comparisons of sectional pressure coefficient distributions with experimental data show good agreement. These threedimensional and time-accurate CFD results can be used for the far-field noise predictions based on the Ffowcs Williams -Hawkings method (FW-H), which can provide a first-principles prediction of both the noise and the underlying turbulent flow that generates the noise, in the context of the wind turbine application.

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“…• Small-scale inlet turbulence, typically due to upstream screens or grids, results in a smooth spectrum at low to middle frequency range [10].…”

Section: A Generating Mechanisms and Shape Of The Spl Spectrummentioning

confidence: 99%

“…Boundary layers developing on the upstream duct walls, as well as wakes due to far away upstream bodies, may be the cause for such a kind of noise [9,10].…”

Section: A Generating Mechanisms and Shape Of The Spl Spectrummentioning

confidence: 99%

Aerodynamic noise from cooling and HVAC systems features important to land vehicles in urban traffic conditions

Canepa

Cattanei

Zecchin

2013

2013 International Conference on Connected Vehicles and Expo (ICCVE)

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Abstract-The present paper deals with the aerodynamic noise generated by cooling and HVAC systems employed in land vehicles. After a brief description of the physical origin of aerodynamic noise, the features important to system engineers dealing with fans installation and operation are considered. First, the main scaling laws useful to estimate the sound level spectrum are reported. Then, the main characteristics of the sound pressure level spectrum are related to the typical aerodynamic generating mechanisms and to the quality of the perceived sound, and some guidelines for noise reduction are listed. Finally, a method for the employ of results obtainable from laboratory tests is proposed which aims to identify the origin of annoying fluctuations in the received noise.

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Broadband and discrete frequency radiation from subsonic rotors

Cited by 87 publications

References 21 publications

Rotor noise due to blade turbulence interaction

Rotor noise due to blade turbulence interaction

3-D Time-Accurate CFD Simulations of Wind Turbine Rotor Flow Fields

Aerodynamic noise from cooling and HVAC systems features important to land vehicles in urban traffic conditions

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