Equivalent Source Method and Boundary Element Method for Calculating Combustion Noise

Piscoya, Rafael; Brick, Haike; Ochmann, Martin; Költzsch, Peter

doi:10.3813/aaa.918060

Cited by 13 publications

(10 citation statements)

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“…He used the Lorentz transformation to introduce the mean flow effect in the ESM and also considered nonuniform flow effects by dividing the flow region into the engine duct and freestream areas. Piscoya et al 63 used the ESM for the prediction of the sound radiation of flames and they compared the ESM with the BEM and showed good agreement between the ESM and the BEM. Dunn 70 into the ESM to substantially reduce computation time and memory usage and solve highfrequency noise for a large-scale aircraft scattering body.…”

Section: Equivalent Source Methodsmentioning

confidence: 99%

Review: The Use of Equivalent Source Method in Computational Acoustics

Lee

2017

J. Comp. Acous.

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This paper reviews the equivalent source method (ESM), an attractive alternative to the standard boundary element method (BEM). The ESM has been developed under different names: method of fundamental solutions, wave superposition method, equivalent source method, etc. However, regardless of the method name, the basic concept is very similar; that is to use auxiliary points called equivalent sources to reconstruct the acoustic pressure for radiation or scattering problems. The strength of the equivalent sources are then determined via various approaches such that the boundary conditions on the boundary surface are satisfied. This paper reviews several frequencydomain and time-domain ESMs. There are several distinct advantages in these types of methods: (1) the method is a meshless approach so that it is easy and simple to implement; (2) it does not have a numerical singularity problem that occurs in the BEM; (3) the number of equivalent sources can be fewer than the number of surface collocation points so that the matrix size is reduced and a fast computation is achieved for large problems. The main issue of the ESM is that there is no rule to find out the optimal number and position of equivalent sources. In addition, the ESM suffers from the numerical instability that is associated with the ill-conditioned matrix. Some guidelines have been suggested in terms of finding the number and position of the sources, and several numerical techniques have been developed to resolve the numerical instability. This paper reviews the common theories, numerical issues and challenges of the ESM, and it summarizes recent developments and applications of the ESM to aircraft noise.

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Section: Equivalent Source Methodsmentioning

confidence: 99%

Review: The Use of Equivalent Source Method in Computational Acoustics

Lee

2017

J. Comp. Acous.

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“…The usual methods can be directly applied to problems containing flow if the region of sound sources is spatially limited, so that a fictitious surface can be considered which encloses all sources and inhomogeneities. In the work from Piscoya et al (2008), the sound radiation from an open jet flame was computed. A cylindrical surface enclosed the flame, and the boundary condition was the normal velocity of the fluid obtained by a Large-Eddy-Simulation (LES).…”

Section: Compact Sourcesmentioning

confidence: 99%

Acoustical Boundary Elements: Theory and Virtual Experiments

Piscoya

Ochmann

2015

Archives of Acoustics

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This paper presents an overview of basic concepts, features and difficulties of the boundary element method (BEM) and examples of its application to exterior and interior problems. The basic concepts of the BEM are explained firstly, and different methods for treating the non-uniqueness problem are described. The application of the BEM to half-space problems is feasible by considering a Green's Function that satisfies the boundary condition on the infinite plane. As a special interior problem, the sound field in an ultrasonic homogenizer is computed. A combination of the BEM and the finite element method (FEM) for treating the problem of acoustic-structure interaction is also described. Finally, variants of the BEM are presented, which can be applied to problems arising in flow acoustics.

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“…WSM has been applied to calculation of acoustic radiation. [15][16][17] However, the prediction accuracy of acoustic pressure using this method strongly depends on the locations of the equivalent sources, particularly for the radiators with complex geometric shapes. Determining the locations becomes a problem.…”

Section: -9mentioning

confidence: 99%

Location Optimization of Monopole Equivalent Sources in Wave Superposition Method

Wu¹,

Xiang²

2018

IJAV

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In wave superposition method, the prediction accuracy of acoustic pressure heavily depends on the locations of equivalent sources. In this paper, the prediction accuracy corresponding to monopole equivalent source is studied. According to analysis in this paper, when the velocities on some boundary nodes are inversely calculated using the predicted pressures, there is velocity reconstruction error, and the prediction error of the acoustic pressure and the velocity reconstruction error are closely related. The relationship between them is theoretically derived and indicates that the prediction error decreases with a decrease in velocity reconstruction error. Based on these findings, a method to determine the optimal locations by minimizing the normalized velocity reconstruction error is proposed. A frequency threshold criterion is devised to give the frequency range for certain number of equivalent sources within which good prediction accuracy of the acoustic pressure can be obtained. The proposed method is validated by simulation and experiment, respectively. The results show that the method significantly reduces prediction errors and is feasible.

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Equivalent Source Method and Boundary Element Method for Calculating Combustion Noise

Cited by 13 publications

References 0 publications

Review: The Use of Equivalent Source Method in Computational Acoustics

Review: The Use of Equivalent Source Method in Computational Acoustics

Acoustical Boundary Elements: Theory and Virtual Experiments

Location Optimization of Monopole Equivalent Sources in Wave Superposition Method

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