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Tuning the selected acoustic helicoidal resonator with a short flat bar - numerical analysis

Łapka Wojciech

Vibrations in Physical Systems

2019

Vol. 30, nr 1

art. no. 2019140

This paper describes the possible way of tuning the selected acoustical helicoidal resonator placed in straight cylindrical duct by the use of a short flat bar. The acoustic attenuation performance (transmission loss) of helicoidal resonator has emphatically changed with the change of the length and the degree of rotation of a short flat bar placed close to the resonator. The finite element numerical calculations of the acoustical systems were made in COMSOL Multiphysics computational environment. The results show that the change of length and rotation of short flat bar can widely change the resonance frequencies of helicoidal resonator. So in this work were presented the possible simple tuning options for the acoustic helicoidal resonator applied in ducted systems.

Numerical Study of Acoustic-Structure Interaction of Selected Helicoidal Resonator with Flexible Helicoidal Profile

Łapka W.

Archives of Acoustics

2018

Vol. 43, No. 1

83--92

The paper presents the results of numerical studies of acoustic-structure interaction of selected helicoidal resonator with helicoidal profile made of an elastic material. Considered a well-recognized acoustic system for one representative type of acoustic helicoidal resonator with two resonant frequencies that correspond to previous studies of the author. Due to the large range of flexible materials to study, this work focuses on the change of material density, Poisson’s ratio and Young’s modulus as the basic parameters describing the properties of elastic materials. The results indicate a significant interaction between the acoustic attenuation performance of helicoidal resonator and elasticity of the helicoidal profile. These interactions are most evident in the frequency range in which the helicoidal resonator is revealed to be effective acoustic damper.