A zonal noise prediction method for trailing-edge noise with a porous model

Bernicke, Paul; Akkermans, R.A.D.; Ananthan, V.B.; Ewert, Roland; Dierke, Jürgen; Rossian, Lennart

doi:10.1016/j.ijheatfluidflow.2019.108469

Cited by 33 publications

(12 citation statements)

References 23 publications

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“…Zamani [21] employed porous media on a vertical-axis wind turbine (VAWT), in which the porous blades experienced a higher stall angle of attack, and enhancements in the power and torque coefficients in the range before and after the optimum tip speed ratio were achieved. Bernicke [22] verified the effectiveness and applicability of porous media with a single vortex passing through a porous trailing edge, which showed the desired effect on noise reduction, underlining the validity of the porous model and its application for airfoil noise reduction. Carpio et al [23] investigated a porous NACA0018 airfoil and proposed that the reduced velocity fluctuations can be another mechanism related to low-frequency noise suppression.…”

Section: Introductionmentioning

confidence: 81%

Numerical Study on Flow and Noise Characteristics of an NACA0018 Airfoil with a Porous Trailing Edge

et al. 2022

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An airfoil with a porous trailing edge has a low noise emission; thus, using a porous medium is a good technique for further reduction of wind turbine noise. In this paper, to reduce airfoil trailing edge noise while minimizing the negative influence of a porous medium on aerodynamic performance, a new filling method is proposed such that a porous medium is only used in the suction side half of the trailing edge, which is more sensitive to the noise generation. The large eddy simulation (LES) technique for flow and the Ffowcs Williams and Hawkings (FW-H) method for acoustics are used. At a Reynolds number of 2.63 × 105 and various angles of attack, an NACA0018 airfoil profile with a porous trailing edge covering 20% of the chord is studied under two porous configurations, namely a fully porous and a suction-side porous trailing edge type. The results show that the flow direction, velocity magnitude, and their distributions along the boundary layer of the two porous airfoils are significantly modified due to the presence of the porous medium. The fluctuation of the pressure coefficient and the increase in the boundary layer thickness are significant at low angles of attack. As compared to the solid airfoil counterpart, the noise radiation from the newly proposed suction-side porous airfoil achieves a noise reduction of 4.3 dB at an angle of attack α = 0°, and a noise reduction of 4.07 dB at an angle of attack α = 2°.

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Section: Introductionmentioning

confidence: 81%

Numerical Study on Flow and Noise Characteristics of an NACA0018 Airfoil with a Porous Trailing Edge

et al. 2022

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“…Pores facilitate the formation of crossflow and vortex shedding; the magnitude depends on the features related to the hole parameters. Eventually, this will affect the turbulence structures [49]. The noise generated can be minimized if a smaller pore size with sub-millimeter diameter, medium to large porosity, and/or small porous coverage is utilized.…”

Section: Noise Controlmentioning

confidence: 99%

“…In addition, porous materials generate noise when air flows over the transition of solid and porous parts. This source increases with the increased permeability [49]. Another reason for the additional noise is surface roughness, low porosity, and vibration of the trailing edge [51].…”

Section: Noise Controlmentioning

confidence: 99%

A Review on Generation and Mitigation of Airfoil Self-Induced Noise

Ibren

Andan

Asrar

et al. 2021

ARFMTS

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A review on passive acoustic control of airfoil self-noise by means of porous trailing edge is presented. Porous surfaces are defined using various terms such as porosity, permeability, resistivity, porosity constant, dimensionless permeability, flow control severity and tortuosity. The primary purpose of this review paper is to provide key findings regarding the sources and mitigation techniques of self-induced noise generated by airfoils. In addition, various parametric design concepts were presented, which are critically important for porous-airfoil design specifications. Most research focus on experimentation with some recent efforts on numerical simulations. Detail study on flow topology is required to fully understand the unsteady flow nature. In general, noise on the airfoil surface is linked to the vortex shedding, instabilities on the surface, as well as feedback mechanism. In addition, acoustic scattering can be minimized by reducing extent of the porous region from the trailing edge while increasing resistivity. Moreover, blowing might also be another means of reducing noise near the trailing edge. Ultimately, understanding the flow physics well provides a way to unveil the unknowns in self-induced airfoil noise generation, mitigation, and control.

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“…Zonal RANS-LES approaches are used more often e.g., by Zhangg et al [4], Erbig and Maihöfer [5], and Kuhn et al [6] and are also used in the CAA community. Terracol [7], Bernicke et al [8], and Satcunanathan et al [9] use a zonal LES approach to predict the trailing edge noise of airfoils. The idea is to extract the acoustic sources inside the zonal domain and apply hybrid CAA methods to predict the far-field noise.…”

Section: Introductionmentioning

confidence: 99%

Zonal direct-hybrid aeroacoustic simulation of trailing edge noise using a high-order discontinuous Galerkin spectral element method

Kempf¹,

Munz²

2022

Acta Acust.

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We present the extension of a discontinuous Galerkin framework to zonal direct-hybrid aeroacoustic simulations. This extension provides the ability to simultaneously perform a zonal large eddy simulation (LES), solving the compressible Navier–Stokes equations, and an acoustic propagation simulation, solving the acoustic perturbation equations. In doing so, the acoustic sources are exchanged without using the file system, and the bottleneck of I/O operations is avoided. This approach is well suited for large-scale simulations done in high-performance computing. The zonal LES uses the recently introduced recycling rescaling anisotropic linear forcing as a turbulent inflow method. We present a methodology to model the required Reynolds stresses based on the distribution of the turbulent kinetic energy obtained from solving the Reynolds-averaged Navier–Stokes equations. We show at the example of a turbulent flow over a flat plate and a NACA 64418 trailing edge simulation that the chosen model of the Reynolds stresses is valid. Direct-hybrid simulation results of a NACA 0012 airfoil, including tonal self-noise and a NACA 64418 trailing edge, demonstrate the presented approach’s applicability. This zonal direct-hybrid simulation approach shows great potential for efficient hybrid computational aeroacoustic simulations in high-performance computing.

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A zonal noise prediction method for trailing-edge noise with a porous model

Cited by 33 publications

References 23 publications

Numerical Study on Flow and Noise Characteristics of an NACA0018 Airfoil with a Porous Trailing Edge

Numerical Study on Flow and Noise Characteristics of an NACA0018 Airfoil with a Porous Trailing Edge

A Review on Generation and Mitigation of Airfoil Self-Induced Noise

Zonal direct-hybrid aeroacoustic simulation of trailing edge noise using a high-order discontinuous Galerkin spectral element method

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