Separated flow noise of a flat plate at large attack angles

Maruta, Yoshiyuki; Kotake, Susumu

doi:10.1016/0022-460x(83)90541-2

Cited by 8 publications

(7 citation statements)

References 4 publications

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“…These works revealed the places with strong pressure fluctuations, while their direct relationship with the sound emission remains unclear. Alternatively, the time derivative of surface pressure has been adopted to represent the noise sources for various aeroacoustic applications (Maruta & Kotake 1983;Tan et al 2018;Casalino et al 2019) as well as rotor noise investigations (Wasala et al 2015;Jiang et al 2022;Zhou, Wang & Wang 2022). While for stationary surfaces it has been revealed that the main noise contribution to the far-field noise is due to the time derivative of surface pressure based on Curle's integral formula (Maruta & Kotake 1983;Tan et al 2018), a discussion on rotating surfaces is still missing.…”

Section: Introductionmentioning

confidence: 99%

“…Alternatively, the time derivative of surface pressure has been adopted to represent the noise sources for various aeroacoustic applications (Maruta & Kotake 1983;Tan et al 2018;Casalino et al 2019) as well as rotor noise investigations (Wasala et al 2015;Jiang et al 2022;Zhou, Wang & Wang 2022). While for stationary surfaces it has been revealed that the main noise contribution to the far-field noise is due to the time derivative of surface pressure based on Curle's integral formula (Maruta & Kotake 1983;Tan et al 2018), a discussion on rotating surfaces is still missing. Therefore, what lacked in previous works is the theoretical explanation and derivation based on the FW-H equation, which will be addressed in this paper.…”

Section: Introductionmentioning

confidence: 99%

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Aeroacoustic sources analysis of wake-ingesting propeller noise

Yangzhou

et al. 2023

J. Fluid Mech.

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High resolution aeroacoustic source analysis is a prerequisite to address the noise concerns and release the full benefits of wake-ingesting propellers. In this work, the aeroacoustic sources of a two-bladed propeller ingesting the wake of an aerofoil are investigated using large eddy simulation in conjunction with two different source identifying approaches. The first approach is the numerical beamforming that utilizes both the classical and wavelet-based beamforming techniques, which determine the phase variations of sources at the low to mid frequencies and reveal that the high-frequency sources are phase-independent. To further improve the spatial resolution of source identification, a new near-field aeroacoustic source analysis approach based on the acoustic analogy is developed in this work. In particular, the on-surface source terms emanating the far-field noise are derived based on the Ffowcs Williams and Hawkings equation for low Mach number flows and constant rotating propellers. Through the incorporation of the simulation results into the proposed source analysis approach, various types of aeroacoustic sources are identified and studied by visualizing their distributions on the propeller surfaces, correlating to flow features and examining the noise spectra and directivity. While the leading edge sources are highly correlated with the wake interaction process, the sources at the mid-chord and the trailing edge of the blade can maintain their strength across most revolving angles. Overall, the proposed analysis approaches extend the capability of computational fluid dynamics and enable the detailed study of noise generation mechanisms of wake-ingesting propeller noise.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Aeroacoustic sources analysis of wake-ingesting propeller noise

Yangzhou

et al. 2023

J. Fluid Mech.

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“…For instance, when the pressure rise across an axial compressor fan increases to such an extent that the flow reverses and separates, or when a wind turbine blade encounters flow heavily disturbed by an upstream turbine [10,11,12]. Additionally, when separation and stall noise does occur it can be expected to produce higher overall sound levels, particularly at lower frequencies [13,12,14], thereby underlining the importance of developing an understanding of the underlying physics of separation and the near-field hydrodynamics to allow future modelling of the radiated far-field stall noise.…”

Section: Introductionmentioning

confidence: 99%

Steady and unsteady loading and radiated far-field sound of three NACA series airfoils in a uniform flow

Branch

Zang

Azarpeyvand

2022

28th AIAA/CEAS Aeroacoustics 2022 Conference

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“…Maruta (1) has studied the relationship between the wake and the aerodynamic noise generated from a flat plate in a uniform flow by a wind tunnel experiments. In this study, it has been experimentally proved that the discrete frequency noise (DFN) decreases with the angle of attack when the angle of attack of the blade is large.…”

Section: Introductionmentioning

confidence: 99%

Application of Wake Characteristics to Prediction of Broadband Noise of a Multiblade Fan

Sasaki

Hayashi

2008

JFST

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In this study, the wake characteristics of an arc blade were measured by the wind tunnel experiment; the characteristics were defined as the width of the wake, diameter of the vortex, ratio of the vortex scale, and the local lift. The influence of the angle of attack on the aerodynamic noise of the blade was quantitatively predicted by using these characteristics. It was clarified experimentally that the sound pressure of the aerodynamic noise becomes small since the gradient of the differential of the lift fluctuation was reduced according to the increase of the angle of attack. The wake characteristics were applied to the prediction of the broadband noise generated from a multiblade fan; the fan noise level distribution was estimated with high accuracy to be in the range from 1000-3000 Hz and was used to analyze the broadband noise of the fan. From the analysis of the fan noise level, it was found that the difference in the relative velocity caused by the biased internal flow was related to the noise levels.

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Separated flow noise of a flat plate at large attack angles

Cited by 8 publications

References 4 publications

Aeroacoustic sources analysis of wake-ingesting propeller noise

Aeroacoustic sources analysis of wake-ingesting propeller noise

Steady and unsteady loading and radiated far-field sound of three NACA series airfoils in a uniform flow

Application of Wake Characteristics to Prediction of Broadband Noise of a Multiblade Fan

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