Polyharmonic Distortion Modelling Applied to Acoustic Characterisation of Peforates

Bodén, Hans

doi:10.2514/6.2011-2724

Cited by 3 publications

(3 citation statements)

References 26 publications

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“…This approach has not been used a lot in acoustics before except for a study on passive nonlinear properties of perforate samples Bodén. 31 The purpose of this paper is therefore to introduce new experimental techniques for studying non-linear energy transfer at perforates and other non-rigid surfaces in ducts and to illustrate how they can be used. It should be pointed out that the type of non-linearity discussed here is local such as the effect of a sudden area change at holes in a perforate plate.…”

Section: Introductionmentioning

confidence: 99%

Experimental source characterization techniques for studying the acoustic properties of perforates under high level acoustic excitation

Bodén

2011

The Journal of the Acoustical Society of America

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This paper discusses experimental techniques for obtaining the acoustic properties of in-duct samples with non-linear acoustic characteristic. The methods developed are intended both for studies of non-linear energy transfer to higher harmonics for samples only accessible from one side such as wall treatment in aircraft engine ducts or automotive exhaust systems and for samples accessible from both sides such as perforates or other top sheets. When harmonic sound waves are incident on the sample nonlinear energy transfer results in sound generation at higher harmonics at the sample (perforate) surface. The idea is that these sources can be characterized using linear system identification techniques similar to one-port or two-port techniques which are traditionally used for obtaining source data for in-duct sources such as IC-engines or fans. The starting point will be so called polyharmonic distortion modeling which is used for characterization of nonlinear properties of microwave systems. It will be shown how acoustic source data models can be expressed using this theory. Source models of different complexity are developed and experimentally tested. The results of the experimental tests show that these techniques can give results which are useful for understanding non-linear energy transfer to higher harmonics.

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Section: Introductionmentioning

confidence: 99%

Experimental source characterization techniques for studying the acoustic properties of perforates under high level acoustic excitation

Bodén

2011

The Journal of the Acoustical Society of America

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“…Two port Sparameters can be used for linear element, but the nonlinear elements generate other harmonic frequencies under single tone frequency. Bodé n [4] applied Polyharmonic Distortion Modelling to Acoustic Characterization of Perforates which was inspired by Jan Verspect who first investigated describing functions which can better model hard nonlinearities in the frequency domain than the Volterra theory [5]. Beside these investigations, Bellet and Cochelin [6] was interested to observe Nonlinear Targeted Energy Transfer (TET) phenomena in duct acoustics with nonlinear membrane; they implemented the equivalent mechanical analogy to interpret the occurrence of the TET.…”

Section: Introductionmentioning

confidence: 99%

Implementation of X-Parameters Principle for Non-linear Vibroacoustic Membrane Using Two-Port Measurement

Moezzi¹,

Hlava²,

Vu³

2019

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X-parameters, a powerful solution to the simulation of nonlinear microwave components, can be used for other wave systems with distributed parameters. This paper introduces Xparameters to the acoustic field to deal with highly nonlinear large signals and boundary conditions. Firstly, an elastic membrane was selected to serve as the nonlinear boundary. Then, the equivalent electronic lumped model of the elastic membrane was established based on its nonlinear differential equation (NDE). The X-parameters of the model were determined by poly-harmonic distortion modelling. Then, an electrical analogy of the nonlinear system was established by two port method. The simulation and experimental results show that the properties of the elastic membrane were characterized well by the X-parameters.

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“…Supposing acoustic plane wave propagation, it is possible to obtain a unique relationship between the upstream and downstream propagating waves and the acoustic impedance. This technique benefits from the reduced number of microphones required to accurately compute the acoustic impedance, it does not require an anechoic termination and, with the use of a polyharmonic distortion model [13], it is possible to take into account non-linear effects in the two-port transfer matrix.…”

Section: Introductionmentioning

confidence: 99%

Indirect acoustic impedance eduction in presence of flow based on an analytical two-port formulation

Santana

Roeck

Desmet

2014

Mechanical Systems and Signal Processing

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In order to assess the performance of advanced acoustic absorbing materials the acoustic impedance should be determined with high accuracy, especially, in presence of a grazing flow. This paper presents an analytical methodology for the grazing flow acoustic impedance eduction, based on a two-port representation of an acoustic system. This procedure is dedicated to the frequency range below the cut-on frequency of the transversal duct modes and its major appeal refers to a reduced number of microphones and the experimental rig simplicity. The methodology is verified by comparison with acoustic finite element simulations. Experiments are performed on two liner configurations and the educed impedance is compared with reference results obtained with a different approach at another test rig, and shows good agreement. A sensitivity analysis on the influence of the input parameters is carried out showing the influence of the rigid-/impedance wall transition effects, flow Mach number, number of microphones and microphone positioning accuracy.

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Polyharmonic Distortion Modelling Applied to Acoustic Characterisation of Peforates

Cited by 3 publications

References 26 publications

Experimental source characterization techniques for studying the acoustic properties of perforates under high level acoustic excitation

Experimental source characterization techniques for studying the acoustic properties of perforates under high level acoustic excitation

Implementation of X-Parameters Principle for Non-linear Vibroacoustic Membrane Using Two-Port Measurement

Indirect acoustic impedance eduction in presence of flow based on an analytical two-port formulation

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