The use of acoustically tuned resonators to improve the sound transmission loss of double panel partitions
01 Oct 1986-
TL;DR: In this paper, the potential effectiveness of tuned Helmholtz resonators connected to the partition cavity is investigated as a method of improving transmission loss, which is demonstrated by a simple theoretical model and then experimentally verified.
Abstract: Double-leaf partitions are often utilized in situations requiring low weight structures with high transmission loss, an example of current interest being the fuselage walls of propeller-driven aircraft. In this case, acoustic excitation is periodic and, if one of the frequencies of excitation lies in the region of the fundamental mass-air-mass frequency of the partition, insulation performance is considerably less than desired. The potential effectiveness of tuned Helmholtz resonators connected to the partition cavity is investigated as a method of improving transmission loss. This is demonstrated by a simple theoretical model and then experimentally verified. Results show that substantial improvements may be obtained at and around the mass-air-mass frequency for a total resonator volume 15% of the cavity volume.
Citations
More filters
01 Jan 2015
3 citations
Cites background from "The use of acoustically tuned reson..."
...Comme présenté sur la Figure 2.10, un résonateur semblable à celui de Helmholtz a été breveté par les compagnies Oerlikon-Contraves et Dornier [59]....
[...]
...Par exemple, dans le cas d’un résonateur de Helmholtz, l’air au niveau du goulot joue l’effet de la masse et la raideur de l’air dans la cavité joue l’effet du ressort....
[...]
...(c) Effet d’une fréquence de résonance 20% supérieur à la fréquence de respiration (d) Effet du facteur de qualité [45] ....
[...]
...Control of sound transmission into payload fairings using distributed vibration absorbers and Helmholtz resonators....
[...]
...En effet, la fréquence propre d’un résonateur de Helmholtz est donnée par : (2.2) Avec , et sont respectivement la surface du col, son rayon et sa longueur. est le volume du résonateur sans le col. Dans le cas du résonateur à cornet cette fréquence est plutôt donnée par [59]: (2.3) avec , , et sont respectivement la surface des ouvertures au niveau du bas de cornet, le diamètre de ce dernier, le diamètre au niveau du haut du cornet et la profondeur du cornet. et sont des longueurs empiriques de correction. est le volume de l’air emprisonné dans le tore (coloré en rose)....
[...]
TL;DR: In this article , a new approach for improving the bandwidth of plate-type acoustic metamaterials by using Helmholtz resonators which represent the added masses is investigated, which gives rise to an additional peak in the transmission loss spectrum which can be tuned to increase the bandwidth.
2 citations
01 Jan 2018
TL;DR: In this paper, a comparison between models (numerical and analytical) and experiment to evaluate the sound absorption of a Helmholtz resonator when it is alone or inserted in porous material is presented.
Abstract: This work presents a comparison between models (numerical and analytical) and experiment to evaluate the sound absorption of a Helmholtz resonator when it is alone or inserted in porous material. For this, the analytical formulation of the resonator and the transfer matrix of serial (TMM) and parallel (P-TMM) methods were presented. In the sequence the numerical model used was presented with the necessary information for the construction of its geometry, the boundary conditions used and its mesh. Finally, the numerical results were validate with analytical results (TMM and P-TMM) and impedance tube experiment.
2 citations
Additional excerpts
...Se uma onda plana incide em um meio multicamadas com ângulo de inclinação θ , é possível determinar o coeficiente de reflexão R e o coeficiente de absorção sonora α , [2, 5, 7, 12]:...
[...]
01 Jan 2018
TL;DR: In this paper, the use of several panels of Helmholtz resonators as a double wall assembly is investigated, and several cases are simulated and investigated using the transfer matrix method.
Abstract: With rising concern pertaining to sound pollution and how it affects public health, new technologies are being considered to ensure sound is effectively attenuated and human exposure to unwanted noise is minimized. One of these technologies that separate the source from the observer is called the partition. As single wall partitions have to be physically dense to provide robust sound attenuation, they are not an efficient solution. An alternative solution is called double wall partitions. Double wall assemblies are lightweight, low-cost alternatives to single wall partitions that provide powerful transmission loss. Despite this, the performance of these assemblies suffer at a frequency called the mass-air-mass resonance frequency. Acoustically reinforcing this assembly is important to ensure their performance over a large frequency range. Helmholtz resonators are powerful methods to block sound in a narrow frequency band, and thus seem perfect to implement in double panel windows. However, when implemented, around the immediate vicinity of the Helmholtz resonator resonance, the performance of the entire assembly deteriorates. In this study, the use of several panels of Helmholtz resonators as a double wall assembly is investigated. As two panels can be set up in several configurations, the new configurations provide additional degrees of freedom that can be used to tune these sound packages to perform well at certain frequencies. Using the transfer matrix method, several cases are simulated and investigated. In certain configurations, improvement of up to 20db is noticed at the Helmholtz resonator resonant frequency. Several cases are also studied for when a porous layer is incorporated into the system.
1 citations
Cites background from "The use of acoustically tuned reson..."
...For example, the global transfer matrix for the simple double wall assembly illustrated in figure (5) would be assembled as follows....
[...]
...Allard in his book derives the acoustic impedance of a square cavity as(27): Zsq = −jZc sicot(kdg) + jωεiρ0 (5)...
[...]
TL;DR: In this paper , an improvement of the sound transmission loss of a finite plate realized by attaching a slit-type Helmholtz resonator or a slit resonator in a parallel arrangement is studied.
References
More filters
TL;DR: In this paper, the effect of different aperture geometries on the resonance frequency of resonators is considered and illustrated by examples, considering losses due to viscosity, heat conduction, and radiation, the optimum design for maximum resonance absorption is analyzed, and the results are expressed in terms of design charts.
Abstract: Absorption and scattering from resonators in a free field as well as in walls are discussed. The effect of different aperture geometries on the resonance frequency of resonators is considered and illustrated by examples. Considering losses due to viscosity, heat conduction, and radiation, the optimum design for maximum resonance absorption is analyzed, and the results are expressed in terms of design charts. Nonlinear effects on the absorption and resonance frequency are also included, and a discussion of the onset of turbulence is presented.
751 citations
TL;DR: In this article, a single Helmholtz resonator is coupled to an enclosure and tuned to the natural frequency of one of its low-order acoustic modes, and the effect on the free, and forced, vibrations of the fluid in the enclosure is analyzed.
94 citations
TL;DR: In this article, an analytical model of fully coupled structural-acoustic-HRs within a double wall structure is established, and the authors illustrate the potential of the active control approach using smart piezoelectric materials and different control actuators (i.e., loudspeakers in the cavity, PZT actuators applied to one of the plates) to improve the transmission loss through double wall structures.
54 citations
TL;DR: In this article, an experimental investigation of passively controlling sound transmission through a double glazed window by using arrangement of Helmholtz resonators (HRs), which are commonly used for narrow band control application, is presented.
43 citations
TL;DR: This work investigates the absorption and transmission acoustic performances of a cellular porous material with a two-dimensional periodic arrangement of HR inclusions with a low frequency model of a resonant periodic unit cell based on the parallel transfer matrix method.
Abstract: Porous materials are widely used for improving sound absorption and sound transmission loss of vibrating structures. However, their efficiency is limited to medium and high frequencies of sound. A solution for improving their low frequency behavior while keeping an acceptable thickness is to embed resonant structures such as Helmholtz resonators (HRs). This work investigates the absorption and transmission acoustic performances of a cellular porous material with a two-dimensional periodic arrangement of HR inclusions. A low frequency model of a resonant periodic unit cell based on the parallel transfer matrix method is presented. The model is validated by comparison with impedance tube measurements and simulations based on both the finite element method and a homogenization based model. At the HR resonance frequency (i) the transmission loss is greatly improved and (ii) the sound absorption of the foam can be either decreased or improved depending on the HR tuning frequency and on the thickness and properties of the host foam. Finally, the diffuse field sound absorption and diffuse field sound transmission loss performance of a 2.6 m2 resonant cellular material are measured. It is shown that the improvements observed at the Helmholtz resonant frequency on a single cell are confirmed at a larger scale.
43 citations