Acoustic energy absorption and dissipation characteristic of Helmholtz resonator enhanced and broadened by acoustic black hole

In aero engines, noise absorption is realised by acoustic liners, e.g., Helmholtz resonator (HR) liners, which often absorb sound only in a narrow frequency range. Due to developments of new engine generations, an improvement of overall acoustic damping performance and in particular more broadband noise absorption is required. In this paper, a new approach to increase the bandwidth of noise absorption for HR liners is presented. By replacing rigid cell walls in the liner’s honeycomb core structure by flexible polymer films, additional acoustic energy is dissipated. A manufacturing technology for square honeycomb cores with partially flexible walls is described. Samples with different flexible wall materials were fabricated and tested. The acoustic measurements show more broadband sound absorption compared to a reference liner with rigid walls due to acoustic-structural interaction. Manufacturing-related parameters are found to have a strong influence on the resulting vibration behaviour of the polymer films, and therefore on the acoustic performance. For future use, detailed investigations to ensure the liner segments compliance with technical, environmental, and life-cycle requirements are needed. However, the results of this study show the potential of this novel liner concept for noise reduction in future aero-engines.

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The effect of type of sound damper material in the Helmholtz resonator to the output power spectrum of acoustic energy Harvester

Journal of Physics Theories and Applications ◽

10.20961/jphystheor-appl.v3i2.38148 ◽

2019 ◽

Vol 3 (2) ◽

pp. 50

Author(s):

Hedwigis Harindra ◽

Agung Bambang Setio Utomo ◽

Ikhsan Setiawan

Keyword(s):

Energy Harvesting ◽

Power Spectrum ◽

Electric Power ◽

Energy Harvester ◽

Helmholtz Resonator ◽

Acoustic Energy ◽

Acoustic Energy Harvesting ◽

Wasted Energy ◽

Second Peak ◽

Output Electric Power

Acoustic energy harvesting is one of many ways to harness acoustic noises as wasted energy into useful electical energy using an acoustic energy harvester. Acoustic energy harvester that tested by Dimastya (2018) which is consisted of loudspeaker and Helmholtz resonator, produced two-peak spectrum. It is suspected that the first peak is due to Helmholtz resonator resonance and the second peak comesfrom the resonance of the conversion loudspeaker. This research is to experimentally confirm the guess of the origin of the first peak. The experiments are performed by adding silencer materials on the resonator inner wall which are expected to be able to reduce the height of first peak and to know how they affect the output electric power spectrum of the acoustic energy harvester. Three different silencer materials are used, those are glasswool, acoustic foam, and styrofoam, with the same thickness of 12 cm. The results show that glasswool absorbs sound more effectively than acostic foam and styrofoam. The use of glasswool, acoustic foam, and styrofoam with 12 cm thickness lowered the first peak by 90% (from 39 mW to 0,5 mW), 82% (from 39 mW to 0,7 mW), and 82% (from 39 mW to 0,7 mW), respectively. Based on these results, it is concluded that the guess of the origin of the first peak is confirmed.

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A panel acoustic energy harvester based on the integration of acoustic metasurface and Helmholtz resonator

Applied Physics Letters ◽

10.1063/5.0074701 ◽

2021 ◽

Vol 119 (25) ◽

pp. 253903

Author(s):

Xiaobin Cui ◽

Jinjie Shi ◽

Xiaozhou Liu ◽

Yun Lai

Keyword(s):

Energy Harvester ◽

Helmholtz Resonator ◽

Acoustic Energy

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Tunable acoustic energy harvester using Helmholtz resonator and dual piezoelectric cantilever beams

2014 IEEE International Ultrasonics Symposium ◽

10.1109/ultsym.2014.0622 ◽

2014 ◽

Cited By ~ 1

Author(s):

Aichao Yang ◽

Ping Li ◽

Yumei Wen ◽

Caijiang Lu ◽

Xiao Peng ◽

...

Keyword(s):

Energy Harvester ◽

Helmholtz Resonator ◽

Acoustic Energy ◽

Cantilever Beams ◽

Piezoelectric Cantilever

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Electromagnetic based acoustic energy harvester for low power wireless autonomous sensor applications

Sensor Review ◽

10.1108/sr-04-2017-0062 ◽

2018 ◽

Vol 38 (3) ◽

pp. 298-310 ◽

Cited By ~ 6

Author(s):

Izhar ◽

Farid Ullah Khan

Keyword(s):

Energy Harvester ◽

Helmholtz Resonator ◽

Acoustic Energy ◽

Flexible Membrane ◽

Content Type ◽

Electric Generator ◽

Sensor Applications ◽

Real Environment ◽

Autonomous Sensor ◽

First Time

Purpose The purpose of this paper is to develop a novel electromagnetic-based acoustic energy harvester (EH) for the application of wireless autonomous sensors. Design/methodology/approach The developed acoustic EH comprises a Helmholtz resonator (HR), a suspension system that consists of a flexible membrane and a permanent magnet, a couple of coils and a coil holder. Furthermore, the HR, used in the harvester, is designed for a specific resonant frequency based on simulation carried out in COMSOL Multiphysics®. Findings The developed harvester is tested both in lab under harmonic sound pressure levels (SPLs) and in real environment under random SPLs. In lab, when exposed to 100 dB SPL, the harvester generated a peak power of 212 µW. Furthermore, in real environment in vicinity of electric generator, the harvester produced an output voltage of about 110 mV collectively from its both coils. Originality/value In this paper, a novel geometric configuration for electromagnetic-based acoustic EH is proposed. In the developed harvester, two coils are placed in it to achieve enhanced electrical output from it for the first time.

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