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Tuesday, July 9 • 16:30 - 16:50
MODELLING OF NONLINEAR ACOUSTIC HARMONIC INTERACTION EFFECTS FOR PERFORATES

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The effect of high level multi-tone acoustic excitation on the acoustic properties of acoustic liners and perforates has been discussed in a number of papers. It has mainly been based on experimental studies of the nonlinear properties of these types of samples without mean graz-ing or bias flow. Comparisons to a simulation model has also been made in some previous papers. In the present paper a model for the harmonic interaction caused by high level excita-tion will be tested. The idea is to use the so called nonlinear scattering matrix model combined with a semi-empirical model. Results are compared to experimental results for an orifice plate and perforate sample. The research questions of interest are: Can the model previously used to study nonlinear effects at the tonal excitation frequency also be used to describe harmonic interaction effects? That is if we excite the system at a certain frequency can the model de-scribe how much sound that is generated (transferred) at higher harmonics. As part of that in-vestigation nonlinear scattering matrix models will be used both to evaluate simulated and ex-perimental data. This comparison is used to draw conclusions on if the nonlinear scattering matrix model gives physically meaningful results. There are a number of simplifying assump-tions made in order to reach the model used so using the simulated results can be a way to in-vestigate under which conditions they are valid.

Moderators
HB

Hans Boden

Professor, KTH

Authors

Tuesday July 9, 2019 16:30 - 16:50 EDT
Westmount 1