Back-scattering correction and further extensions of Amiet's trailing-edge noise model. Part 1: theory

Roger, Michel; Moreau, Stéphane

doi:10.1016/j.jsv.2004.10.054

Cited by 392 publications

(262 citation statements)

References 22 publications

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“…The model determines the surface pressure fluctuations using the airfoil's lift response and the turbulent energy spectrum normal to the blade and these fluctuations are then propagated to the far-field as sound. It uses a large aspect-ratio, thin airfoil approximation, and while corrections for airfoil shape, thickness and backscattering have been developed they are not yet widely implemented (Moriarty et al 2005, Roger & Moreau 2005, Zhu et al 2005. Predicted and experimental spectrum differ by less than 6dB for frequencies below 1.5kHz, above this however the accuracy of the model appears to decline rapidly (Amiet 1975, Schlinker & Amiet 1983).…”

Section: Turbulent-inflow Noisementioning

confidence: 99%

A discussion of wind turbine interaction and stall contributions to wind farm noise

Laratro

Arjomandi

Kelso

et al. 2014

Journal of Wind Engineering and Industrial Aerodynamics

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Elsevier's Policy: An author may use the preprint for personal use, internal institutional use and for permitted scholarly posting. ... Elsevier's AAM Policy: Authors retain the right to use the accepted author manuscript for personal use, internal institutional use and for permitted scholarly posting provided that these are not for purposes of commercial use or systematic distribution. Elsevier believes that individual authors should be able to distribute their AAMs for their personal voluntary needs and interests, e.g. posting to their websites or their institution's repository, e-mailing to colleagues. However, our policies differ regarding the systematic aggregation or distribution of AAMs to ensure the sustainability of the journals to which AAMs are submitted. Therefore, deposit in, or posting to, subject-oriented or centralized repositories (such as PubMed Central), or institutional repositories with systematic posting mandates is permitted only under specific agreements between Elsevier and the repository, agency or institution, and only consistent with the publisher's policies concerning such repositories. Voluntary posting of AAMs in the arXiv subject repository is permitted. ... Highlights-Rotor-wake interaction plays a role in wind farm noise -More wake data needs to be collected -Dynamic stall noise needs to be characterised AbstractWind farms have recently been reported to produce a noise signature that is described as possessing a "thumping" quality. Measurements of these signatures are limited and their effects are debated but their effect on public opinion and complaints make them a concern for researchers in this field. Proposed reasons for these noise signatures include amplitude modulation, interference patterns and wake-rotor interaction. This paper discusses these effects and concludes that wake-rotor interaction plays a role by causing variations in turbulent-inflow noise and dynamic stall. The current state of research into stall noise and wind turbine wake structure is also reviewed and it is concluded that the available information and collected data on wind turbine wake are insufficient to determine how strong this role is. More information on the velocity and turbulence fields in the wake of horizontal-axis wind turbines as well as a characterisation of the noise produced by an airfoil experiencing dynamic stall is required in order to make a full assessment of rotor-wake contributions to wind farm noise.2

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Section: Turbulent-inflow Noisementioning

confidence: 99%

A discussion of wind turbine interaction and stall contributions to wind farm noise

Laratro

Arjomandi

Kelso

et al. 2014

Journal of Wind Engineering and Industrial Aerodynamics

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“…What is common between all those approaches and the one proposed in this paper is the idea of solving parts of the problem and then bringing the parts together in an iterative manner. Recently, the Schwarzschild's series were used in (Lyu et al 2016;Roger & Moreau 2005) but only to obtain the scattered pressure on the surface of the flat plate, and the far-field sound was obtained using the surface pressure integral based on the theories of Kirchhoff and Curle.…”

Section: Introductionmentioning

confidence: 99%

Aerodynamic noise from rigid trailing edges with finite porous extensions

Kisil

Ayton

2017

J. Fluid Mech.

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This paper investigates the effects of finite flat porous extensions to semi-infinite impermeable flat plates in an attempt to control trailing-edge noise through bio-inspired adaptations. Specifically the problem of sound generated by a gust convecting in uniform mean steady flow scattering off the trailing edge and permeable-impermeable junction is considered. This setup supposes that any realistic trailing-edge adaptation to a blade would be sufficiently small so that the turbulent boundary layer encapsulates both the porous edge and the permeable-impermeable junction, and therefore the interaction of acoustics generated at these two discontinuous boundaries is important. The acoustic problem is tackled analytically through use of the Wiener-Hopf method. A two-dimensional matrix Wiener-Hopf problem arises due to the two interaction points (the trailing edge and the permeable-impermeable junction). This paper discusses a new iterative method for solving this matrix Wiener-Hopf equation which extends to further two-dimensional problems in particular those involving analytic terms that exponentially grow in the upper or lower half planes. This method is an extension of the commonly used "pole removal" technique and avoids the needs for full matrix factorisation. Convergence of this iterative method to an exact solution is shown to be particularly fast when terms neglected in the second step are formally smaller than all other terms retained. The new method is validated by comparing the iterative solutions for acoustic scattering by a finite impermeable plate against a known solution (obtained in terms of Mathieu functions). The final acoustic solution highlights the effects of the permeable-impermeable junction on the generated noise, in particular how this junction affects the far-field noise generated by high-frequency gusts by creating an interference to typical trailing-edge scattering. This effect results in partially porous plates predicting a lower noise reduction than fully porous plates when compared to fully impermeable plates.

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“…This simplification was enhanced later by Zhou and Joseph 33 (2004) for open propellers using Amiet's isolated airfoil response function 8,9 extended to take into account the contribution of skewed gusts, and then extended by Blandeau 3 for contra-rotating open rotors. A significant contribution for the trailing edge noise prediction was achieved by Roger and Moreau 35 , who introduced a correction for the back-scattering of the leading edge. Other applications have been made for instance by Rozenberg for low speed fans, and by Glegg 28 for wind turbines.…”

Section: Introductionmentioning

confidence: 99%

Prediction of Contra-Rotating Open Rotor broadband noise in isolated and installed configurations

Nodé-Langlois

Wlassow

Languille

et al. 2014

20th AIAA/CEAS Aeroacoustics Conference

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Broadband noise is a significant part of the noise emitted by contra-rotating open rotors. Several noise sources can contribute to the total broadband sound field, with the most dominant ones probably being trailing edge noise, rotor-wake interaction noise and pylon-wake interaction noise. This paper addresses the prediction of these noise sources using analytical models based on Amiet's flat plate airfoil theory and also to empirical turbulence models, fed by input data extracted from steady and unsteady CFD RANS simulations. The models are assessed against wind tunnel tests of Rolls-Royce's rig 145 (build 1) conducted at the DNW anechoic open jet test facility using Rolls-Royce blades and Airbus pylons. The study showed promising results in terms of the ability of the models to predict acoustic power spectrum shapes, peak frequencies and absolute levels. The effects of changes in thrust on broadband wake-interaction noise are well reproduced. However, the models significantly underestimate the effect of thrust on trailing edge noise and the effect of rotational velocity on pylon interaction noise. Nomenclature

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Back-scattering correction and further extensions of Amiet's trailing-edge noise model. Part 1: theory

Cited by 392 publications

References 22 publications

A discussion of wind turbine interaction and stall contributions to wind farm noise

A discussion of wind turbine interaction and stall contributions to wind farm noise

Aerodynamic noise from rigid trailing edges with finite porous extensions

Prediction of Contra-Rotating Open Rotor broadband noise in isolated and installed configurations

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