Turbulent boundary layer trailing-edge noise: Theory, computation, experiment, and application

Lee, Seongkyu; Ayton, Lorna J.; Bertagnolio, Franck; Moreau, Stéphane; Chong, Tze Pei; Joseph, Phillip

doi:10.1016/j.paerosci.2021.100737

Cited by 96 publications

(43 citation statements)

References 209 publications

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“…We resort to the a priori error indicator proposed in [43], which adjusts automatically the edge and face orders across the mesh so as to achieve a given user-defined 2 -error target accuracy . The orders are here defined to be in the range FEM ∈ [2,10]. While the conventional strategy consists in creating a different mesh for each frequency of interest, this adaptive approach allows computing solutions seamlessly over a broad frequency range based on a single input mesh.…”

Section: Resolution Of a Helmholtz Problem Using A Finite Element Methodsmentioning

confidence: 99%

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Trailing-Edge Noise Prediction by Solving Helmholtz Equation with Stochastic Source Term

Kadar¹,

Bras²,

Bériot³

et al. 2022

AIAA Journal

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A numerical approach to predict broadband trailing-edge noise for low Mach number flows is presented. It is based on the combination of a Helmholtz solver to propagate sound waves with a sound source term computed stochastically. The sound propagation is performed in the frequency domain using a high-order finite element solver. The stochastic approach is based on a Random Particle-Mesh method. The performance of this numerical approach is first examined for a Gaussian source. The numerical approach is then applied to a NACA0012 airfoil for flow Mach numbers of 0.11 and 0.16 and to a controlled-diffusion airfoil for a Mach number of 0.047. The predicted sound levels are compared with experimental data and acoustic results obtained from the Acoustic Perturbations Equations. The mean flow does not significantly modify the acoustic propagation. Using a no-flow propagation model like the Helmholtz equation is therefore a valid approach for low Mach numbers. The reduced computational cost of a Helmholtz calculation, together with the speed of the RPM turbulence synthesis, allows for fast predictions. While this approach provides relative assessments between different configurations (in particular the spectrum shape), it often requires the inclusion of calibration factors determined from reference measurement or numerical data.

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Section: Resolution Of a Helmholtz Problem Using A Finite Element Methodsmentioning

confidence: 99%

“…the dominant source of noise of low-speed cooling fans, wind turbines or aircraft lifting surfaces [1,2]. This mechanism remains even in the absence of incoming free stream turbulence.…”

mentioning

confidence: 99%

Trailing-Edge Noise Prediction by Solving Helmholtz Equation with Stochastic Source Term

Kadar¹,

Bras²,

Bériot³

et al. 2022

AIAA Journal

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“…Numerical investigation of VGs by scale-resolving methods performed by Mereu et al 65 The authors conclude that scale-resolving approach provides better results than RANS modeling and that it is possible to capture the stalling angle with 64 (c) wavy leading edge, 77 and (d) sawtooth trailing edge. 80 higher accuracy. Numerical simulation, performed using very-large-eddy/lattice-Boltzmann method, 66 focuses on the effect of vortex generators on the aerodynamic performance and far-field noise.…”

Section: Passive Flow Controlmentioning

confidence: 97%

“…The potential application of leading edge modifications to small-scale wind turbines is covered in Zhao et al 72 and Zadorozhna et al, 79 The conclusion of Zadorozhna et al 79 is that small tubercles outperform the larger ones. A very detailed study on trailing-edge noise that also examines different ways to mitigate it (by sawtooth, sketched in Figure 2(d), and sinusoidal trailing edge serrations) is given by Lee et al 80 The modifications (serrations) applied to wind turbine blades, rotorcrafts, fans serve to scatter the pressure field fluctuations. Porous coating can also be used for the same purpose.…”

Section: Passive Flow Controlmentioning

confidence: 99%

Current state and future trends in boundary layer control on lifting surfaces

Svorcan

Wang

Griffin

2022

Advances in Mechanical Engineering

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Successful flow control may bring numerous benefits, such as flow stabilization, flow reattachment, separation delay, drag reduction, lift increase, aerodynamic performance improvement, energy efficiency increase, shock delay or weakening, noise reduction, etc. For these purposes, many different flow control devices, which can be classified as passive, semi-active and active, have been designed and tested. This review paper aims to highlight the most promising and commonly employed boundary layer control methods as well as outline their potential in specific applications in aerospace and energy engineering. Referenced studies, performed on various geometries (flat plates, channels, airfoils, wings, blades, cylinders), are primarily numerical or experimental. Although enhanced aerodynamic performance is achieved in many cases, further research is required to draw general conclusions. This paper aims to demonstrate that, in the future, we may expect further developments of flow control actuators, as well as their increased application.

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“…1 The eddies developed within the turbulent boundary layer near the trailing edge generate unsteady surface pressure fluctuations, and the scattering of this wall-bounded pressure fluctuations by a sharp trailing edge induces trailing-edge noise. 2 This noise is notably important for wind turbine 3 and rotorcraft 4–6 applications as well as aircraft during landing. Trailing-edge noise is sensitive to airfoil shape and size, 7,8 in addition to flow conditions.…”

Section: Introductionmentioning

confidence: 99%

Effect of 2D ice accretion on turbulent boundary layer and trailing-edge noise

Gill

Lee

2022

International Journal of Aeroacoustics

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Trailing-edge noise is known to be sensitive to airfoil shapes, and ice accretion is one cause of an airfoil shape deformation. This paper investigates how trailing-edge noise is affected by the airfoil shape deformation due to ice accretion. The formation of ice-induced flow separation and the development of a turbulent boundary layer are analyzed to understand the correlation between the altered flow physics due to ice accretion inside the boundary layer and trailing-edge noise. The near-wall flow behind the leading-edge ice accretion is analyzed by using Reynolds-Averaged Navier Stokes CFD in OpenFOAM, and trailing-edge noise is investigated using an empirical wall pressure spectrum model in conjunction with Amiet’s trailing-edge noise theory. Validations of tools against measurement data are presented. Liquid water content, freestream velocity, and ambient temperature are varied to investigate the impact of flow conditions on the ice accretion shape and the resulting boundary layer flow characteristics at the trailing edge. It is found that a more significant leading edge deformation due to ice accretion generates larger ice-induced flow separation bubbles, which increases the trailing-edge boundary layer thickness. As a result, an increase in low- and mid-frequency noise is observed. The purpose of this paper is not only to understand the effect of ice accretion on trailing-edge noise but also to comprehensively analyze how flow physics inside the turbulent boundary layer is altered by the presence of various ice accretion shapes.

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Turbulent boundary layer trailing-edge noise: Theory, computation, experiment, and application

Cited by 96 publications

References 209 publications

Trailing-Edge Noise Prediction by Solving Helmholtz Equation with Stochastic Source Term

Trailing-Edge Noise Prediction by Solving Helmholtz Equation with Stochastic Source Term

Current state and future trends in boundary layer control on lifting surfaces

Effect of 2D ice accretion on turbulent boundary layer and trailing-edge noise

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