scholarly journals Excited resonance widths for Helmholtz resonators with straight neck

2020 ◽  
Vol 10 (2) ◽  
pp. 561-580
Author(s):  
Thomas Duyckaerts ◽  
Alain Grigis ◽  
André Martinez
Keyword(s):  
Helmholtz Resonators ◽  
Excited Resonance

Noise control of outdoor unit of split type air-conditioner using periodic scatterers made with array of Helmholtz resonators

2021 ◽  
Vol 179 ◽  
pp. 108054
Author(s):  
J. Dandsena ◽  
K. Mohapatra ◽  
A.K. Satapathy ◽  
D.P. Jena
Keyword(s):  
Noise Control ◽  
Air Conditioner ◽  
Helmholtz Resonators

Sound Attenuation in a Flow Duct Periodically Loaded With Micro-Perforated Patches Backed by Helmholtz Resonators

2018 ◽  
Author(s):  
T. Bravo ◽  
C. Maury
Keyword(s):  
Separation Distance ◽  
Side Branch ◽  
Optimal Choice ◽  
Sound Attenuation ◽  
Limited Area ◽  
Frequency Noise ◽  
Matrix Formulation ◽  
Wave Regime ◽  
Helmholtz Resonators ◽  
Periodic Distribution

Mitigating the propagation of low frequency noise sources in ducted flows represents a challenging task since wall treatments have often a limited area and thickness. Loading the periphery of a duct with a periodic distribution of side-branch Helmholtz resonators broadens the bandwidth of the noise attenuated with respect to a single resonator and generates stop bands that inhibit wave propagation. However, significant flow pressure drop may occur along the duct axis that could be reduced using micro-perforated patches at the duct-neck junctions. In this study, a transfer matrix formulation is derived to determine the sound attenuation properties of a periodic distribution of MPPs backed by Helmholtz resonators along the walls of a duct in the plane wave regime. In the no-flow case, it is shown that an optimal choice of the MPP parameters and resonators separation distance lowers the frequencies of maximal attenuation while maintaining broad stopping bands. As observed in the no-flow and low-speed flow cases, these frequencies can be further decreased by coiling the acoustic path length in the resonators cavity, albeit at the expense of narrower bands of low pressure transmission. The achieved effective wall impedances are compared against Cremer optimal impedance at the first attenuation peak.

Resonance frequencies and sound absorption of Helmholtz resonators with multiple necks

2019 ◽  
Vol 145 ◽  
pp. 314-319 ◽  
Author(s):  
F. Langfeldt ◽  
H. Hoppen ◽  
W. Gleine
Keyword(s):  
Sound Absorption ◽  
Helmholtz Resonators ◽  
Resonance Frequencies
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