Rapid noise prediction models for serrated leading and trailing edges

Lyu, Benshuai; Ayton, Lorna J.

doi:10.1016/j.jsv.2019.115136

Cited by 38 publications

(22 citation statements)

References 34 publications

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“…The prediction of the far-field noise from a serrated airfoil of chord 'C' and span 'y' in a uniform stream of velocity U is considered by Lyu and Ayton [25], which provides an analytical solution for the TE noise using the Wiener-Hopf method as follows:…”

Section: Development Of An Analytical Model To Predict the Far-field ...mentioning

confidence: 99%

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On the Reductions of Airfoil Broadband Noise through Sinusoidal Trailing-Edge Serrations

et al. 2022

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The present study investigates the efficacy of sinusoidal trailing edge (TE) serrations as a passive means for the reductions of airfoil broadband noise, theoretically and experimentally.Comprehensive parametric studies are conducted to determine the effect of serration amplitudes and wavelengths on the noise reduction performance of a NACA airfoil. Initially, the present paper shows the use of the Trailing-Edge Noise Model (TNO) for the accurate predictions of the surface pressure spectrum near the TE and hence the far-field noise using the Wiener-Hopf method. The predicted spectra and the noise reduction levels showed good agreement with the measurements for a wide range of frequencies. The present study reveals that the local maxima of the overall noise reductions occur when the transverse turbulence integral length scale is either 1.2 or 0.2 times the serration wavelength, which corresponds to λ/Λt = 0.833 or 5, where λ and Λt are the serration wavelength and integral length scale. One of the key findings of the paper is that the serration wavelength at which the highest noise reductions occur when the acoustic emissions vary inversely with the modified Strouhal number Sthm (i.e., wsste (ω)/wbl (ω) ∝ 1/Sthm) for narrow (i.e., small wavelengths) and wider serrations (i.e., large wavelengths), where wsste and wbl are the acoustic emissions radiated from the serrated and baseline airfoils. Further, the TE serrations are also observed to reduce leading-edge (LE) noise along with the self-noise, which indicates the efficacy of TE serrations in reducing the total far-field noise.

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Section: Development Of An Analytical Model To Predict the Far-field ...mentioning

confidence: 99%

“…where 𝑘 is defined by 𝑘 = The surface-pressure spectrum Πt is calculated by the Chase model in (Lyu and Ayton [25] and…”

Section: Development Of An Analytical Model To Predict the Far-field ...mentioning

confidence: 99%

On the Reductions of Airfoil Broadband Noise through Sinusoidal Trailing-Edge Serrations

et al. 2022

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“…) and u c is the convection velocity taken as 70% of the free-stream velocity following a common practice in noise prediction [32,34]. The simplest and most common model for the spanwise coherence length is Corcos' model [52].…”

Section: Description Of the Modelmentioning

confidence: 99%

“…This includes the pioneering theoretical work of Howe [31] who published a Green's function-based analytical model for noise prediction of a semi-infinite serrated flat-plate. Lyu's and Ayton's [32][33][34] approaches are both based on the same governing equation but the Wiener-Hopf technique used in their most recent work considerably reduces the number of sums to compute in the model resulting in a much faster implementation. These models essentially spread a modulated single-point wall pressure fluctuations spectrum along the serrated edge and only account for cut-on modes.…”

Section: Introductionmentioning

confidence: 99%

Broadband noise prediction for aerofoils with a serrated trailing edge based on Amiet’s theory

Gelot

Kim

2021

Journal of Sound and Vibration

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“…Even though serrations are widely used, the prediction of trailing-edge serration noise (Howe 1991a,b;Lyu, Azarpeyvand & Sinayoko 2016;Ayton 2018;Lyu & Ayton 2020) is still an ongoing subject of research, given that large deviations between experiments and analytical predictions are often reported (Gruber, Joseph & Chong 2011;Arce León et al 2016;Lyu & Ayton 2020). Consequently, predictions of noise reduction from wind turbines with serrations still require dedicated experiments or numerical simulations, whereas a fast assessment and physical interpretation could be provided by more advanced analytical methods that can capture the dominant effects introduced by the serrations.…”

Section: Introductionmentioning

confidence: 99%

A physics-based description and modelling of the wall-pressure fluctuations on a serrated trailing edge

et al. 2022

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A physical description of the flow mechanisms that govern the distribution of the wall-pressure fluctuations over the surface of a serrated trailing edge is proposed. Three main mechanisms that define the variation of turbulent pressure fluctuations across the serrated edge are discussed and semi-empirical models are formulated accordingly. It is shown that the intensity of the wall-pressure fluctuations increases at the tips under the effect of an increased convective velocity as a result of sidewise momentum diffusion. Furthermore, the change of impedance across the edge causes a local reduction of the pressure fluctuations in the vicinity of the trailing edge. Finally, aerodynamic loading over the serrations due to the non-symmetric flow created at different angles of attack establishes secondary flow patterns that induce higher wall-pressure fluctuations over the serration edges. The latter effect is present only for serrations under high aerodynamic loading, while the former ones are observed under any conditions. Semi-empirical models are formulated for predicting the variation of the wall-pressure fluctuations over the serration surface based on the three physical mechanisms described. These models are calibrated and compared against experiments conducted on a symmetric airfoil model at high Reynolds numbers.

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Rapid noise prediction models for serrated leading and trailing edges

Cited by 38 publications

References 34 publications

On the Reductions of Airfoil Broadband Noise through Sinusoidal Trailing-Edge Serrations

On the Reductions of Airfoil Broadband Noise through Sinusoidal Trailing-Edge Serrations

Broadband noise prediction for aerofoils with a serrated trailing edge based on Amiet’s theory

A physics-based description and modelling of the wall-pressure fluctuations on a serrated trailing edge

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