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Applied Sciences
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Recent Advances in Noise Barriers
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Recent Advances in Noise Barriers

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Acoustics and Vibrations".

Deadline for manuscript submissions: closed (31 January 2023) | Viewed by 14926

Special Issue Editor

Prof. Dr. Javier Redondo

E-Mail Website
Guest Editor
Department of Applied Physics, Polytechnic University of Valencia, 46022 Valencia, Spain
Interests: noise barriers; numerical methods; sonic crystals
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Research on noise barriers has drastically evolved in the last few years, on the one hand, due to the evolution of numerical methods and, on the other hand, because of the performance increase of the hardware available to researchers.

Adaptations, improvements and combinations of numerical methods have allowed researchers to go one step further, providing faster and better simulations not only of conventional noise barriers but also of more recent proposals such as noise barriers based on metamaterials.

I think it is about time that a scientific journal devoted a Special Issue to compiling these advances as well as new, more or less complex proposals for the prediction of noise barriers, to protect us from the noise caused by transport infrastructures.

Prof. Dr. Javier Redondo
Guest Editor

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • noise barriers
  • numercial methods
  • models and theoretical acoustics

Published Papers (7 papers)

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Research

13 pages, 3562 KiB  
Article
Increasing the Insertion Loss of Sonic Crystal Noise Barriers with Helmholtz Resonators
by Javier Redondo, David Ramírez-Solana and Rubén Picó
Appl. Sci. 2023, 13(6), 3662; https://doi.org/10.3390/app13063662 - 13 Mar 2023
Cited by 6 | Viewed by 1564
Abstract
Helmholtz resonators (HRs) have the advantage of extending and improving their insulating capacity when used as scatterers in noise barriers made of periodic media, such as sonic crystals (SCs). However, the interaction between multiple Bragg scattering and local resonance phenomena can increase or [...] Read more.
Helmholtz resonators (HRs) have the advantage of extending and improving their insulating capacity when used as scatterers in noise barriers made of periodic media, such as sonic crystals (SCs). However, the interaction between multiple Bragg scattering and local resonance phenomena can increase or decrease the insulation of the barrier depending on its design. In the present work, we numerically investigate the factors that determine how such interferences occur and the specific conditions to increase the insertion loss of sonic crystal noise barriers (SCNBs) made of cylindrical scatterers with HRs. Two factors are crucial for the variation of the isolation of the barrier in the Bragg-bandgap (Bragg-BG): the orientation of the resonator mouth with respect to the incident wave, and the resonance frequency of the resonator with respect to the central frequency of the Bragg-BG. Based on this phenomenon, we propose a sonic crystal noise barrier consisting of scatterers with two Helmholtz resonators. The insertion loss of the structure is determined numerically and shows an increase of 20 dB at the BG compared to a conventional barrier with cylindrical scatterers. Full article
(This article belongs to the Special Issue Recent Advances in Noise Barriers)
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21 pages, 4992 KiB  
Article
Experimental Analysis and Simulation of a Porous Absorbing Layer for Noise Barriers
by Laura Sousa, Luís Pereira, David Montes-González, Denilson Ramos, Paulo Amado-Mendes, Juan Miguel Barrigón-Morillas and Luís Godinho
Appl. Sci. 2023, 13(4), 2638; https://doi.org/10.3390/app13042638 - 18 Feb 2023
Cited by 6 | Viewed by 1758
Abstract
Noise barriers are common noise mitigation measures usually implemented near roads or railways, with proven efficiency. This work presents a study of a porous concrete material incorporating expanded clay as aggregate, to be used on the sound-absorption layer of noise barriers. A theoretical [...] Read more.
Noise barriers are common noise mitigation measures usually implemented near roads or railways, with proven efficiency. This work presents a study of a porous concrete material incorporating expanded clay as aggregate, to be used on the sound-absorption layer of noise barriers. A theoretical material model is calibrated using experimental data and then used to estimate the diffuse field sound absorption from the normal incidence sound absorption estimation/measurement. Validation of such estimation is performed by comparing to reverberant room measurements. Numerical simulations are carried out using the boundary element method (BEM) and the CNOSSOS-EU calculation method to assess the performance of different types of barriers incorporating this material. L-shaped and vertical barriers are tested, as well as low-height and conventional (taller) barriers, employed in the context of a railway noise scenario. Different results are obtained by the two methods, mainly due to the different underlying physical principles. Good insertion loss values may be obtained using both conventional and low-height noise barriers together with the porous concrete material if a careful choice of its location within the barrier is made. Full article
(This article belongs to the Special Issue Recent Advances in Noise Barriers)
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16 pages, 5085 KiB  
Article
Experimental and Numerical Investigation of Sound Absorption Characteristics of Rebonded Polyurethane Foam
by Milica Jovanoska Mitrevska, Viktor Mickovski, Todorka Samardzioska and Gino Iannace
Appl. Sci. 2022, 12(24), 12936; https://doi.org/10.3390/app122412936 - 16 Dec 2022
Cited by 2 | Viewed by 2552
Abstract
Polyurethane foam (PUF) is an exceptionally adaptable product that has a variety of applications—it can be found almost everywhere. Due to such high utilization, the amount of polyurethane foam waste generated each year is growing over time. Rebonding polyurethane foam waste is a [...] Read more.
Polyurethane foam (PUF) is an exceptionally adaptable product that has a variety of applications—it can be found almost everywhere. Due to such high utilization, the amount of polyurethane foam waste generated each year is growing over time. Rebonding polyurethane foam waste is a suitable way to progress towards a circular economy. In this paper, the prospect of using rebonded polyurethane foam (RPUF) in noise control applications is examined. An experimental study was carried out on RPUFs with various thicknesses and densities. The sound absorption coefficients at normal incidence and air resistivity were measured. The five-parameter Johnson-Champoux-Allard (JCA) model was adopted for the simulation of the porous layer. The remaining unknown parameters of the JCA model were estimated by inverse acoustic characterization based on fitting the transfer matrix method (TMM) model of an unbounded porous layer with rigid backing to the experimentally obtained sound absorption coefficients. Furthermore, sound absorption coefficients were calculated for a wide range of sample thicknesses, as well as for different air gap thicknesses between the wall and the porous layer. For some of the considered RPUFs, a sound absorption coefficient above 0.8 was achieved over a wide frequency range. Full article
(This article belongs to the Special Issue Recent Advances in Noise Barriers)
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22 pages, 9571 KiB  
Article
Study on Characteristics and Control of Aerodynamic Noise of a High-Speed Centrifugal Air Compressor for Vehicle Fuel Cells
by Shizhong Sun, Ziwen Xing, Wenqing Chen, Minglong Zhou, Chuang Wang and Hanyang Cui
Appl. Sci. 2022, 12(19), 9962; https://doi.org/10.3390/app12199962 - 4 Oct 2022
Viewed by 2216
Abstract
As the main noise source in the hydrogen fuel cell system, the noise level of the centrifugal air compressor greatly affects the comfort of the hydrogen fuel cell vehicle. For reducing the noise level of centrifugal air compressors, the noise characteristics and control [...] Read more.
As the main noise source in the hydrogen fuel cell system, the noise level of the centrifugal air compressor greatly affects the comfort of the hydrogen fuel cell vehicle. For reducing the noise level of centrifugal air compressors, the noise characteristics and control of a high-speed two-stage compressor prototype are studied in this paper. Firstly, the near-field noise measurement, along with the independent component analysis, is carried out to identify the noise source of the developed compressor. Results showed that the “buzz-saw” noise at the rotating fundamental frequency and its low order harmonic frequency in the aerodynamic noise is prominent in the noise spectrum. Thus, the aerodynamic noise characteristics are predicted and analyzed using the CFD–BEM coupling aeroacoustic calculation model. Based on the analysis results, a noise control method coupling the structure optimization and perforated muffler is proposed. The results show that the sound pressure level of the air compressor at 1 m away from the surface is reduced by 4.1 dBA after the structural optimization. A perforated muffler applied in the pipe system of the air compressor can accomplish a reduction of 5.8 dBA in the sound pressure level of the air compressor by impeding the noise transmission on the path. With the coupled noise control methods above, the sound pressure level of the air compressor is reduced from 78.8 dBA to 68.9 dBA under the rated condition. Full article
(This article belongs to the Special Issue Recent Advances in Noise Barriers)
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13 pages, 2419 KiB  
Article
A Simple Method to Estimate the In Situ Performance of Noise Barriers
by Javier Redondo, Pau Gaja-Silvestre, Luis Godinho and Paulo Amado-Mendes
Appl. Sci. 2022, 12(14), 7027; https://doi.org/10.3390/app12147027 - 12 Jul 2022
Cited by 2 | Viewed by 1836
Abstract
Noise barriers are usually classified attending to their intrinsic acoustic characteristics. This is standardized by the European Standards EN 1793, parts 2 and 6, in which a single parameter, DLR or DLSI, is defined in order to quantify the sound [...] Read more.
Noise barriers are usually classified attending to their intrinsic acoustic characteristics. This is standardized by the European Standards EN 1793, parts 2 and 6, in which a single parameter, DLR or DLSI, is defined in order to quantify the sound insulation performance of noise barriers. However, the final performance of a noise barrier, quantified by the so-called insertion loss, IL is not only dependent on the insulation provided by the noise barrier, but it is as well affected by geometrical aspects and the acoustic characteristics of the environment where these noise-reducing devices are placed. In this work, we explore the relationship between the insertion loss and the acoustic insulation by means of numerical methods. Moreover, the authors propose a simple way to predict the insertion loss from a purely acoustic numerical simulation in which this parameter is obtained for a completely rigid noise barrier, and knowing the noise barrier’s sound reduction index, in one third octave bands. Full article
(This article belongs to the Special Issue Recent Advances in Noise Barriers)
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15 pages, 2742 KiB  
Article
2D Sonic Acoustic Barrier Composed of Multiple-Row Cylindrical Scatterers: Analysis with 1:10 Scaled Wooden Models
by Antonella Bevilacqua, Gino Iannace, Ilaria Lombardi and Amelia Trematerra
Appl. Sci. 2022, 12(13), 6302; https://doi.org/10.3390/app12136302 - 21 Jun 2022
Cited by 4 | Viewed by 1116
Abstract
Theory regarding metamaterials was developed in the 1960s, aiming to control the propagation of electromagnetic waves. Under this scope, research has been focused on the realization of materials having specific characteristics to be invisible to the electromagnetic and optics fields. These principles have [...] Read more.
Theory regarding metamaterials was developed in the 1960s, aiming to control the propagation of electromagnetic waves. Under this scope, research has been focused on the realization of materials having specific characteristics to be invisible to the electromagnetic and optics fields. These principles have been expanded only recently to the acoustic sector, with metamaterials capable of controlling the sound propagation due to the interference effect between the soundwaves and the periodic structural elements composing the system. This paper deals with sound attenuation and analyzes a metamaterial acoustic barrier characterized by multiple rows in different configurations. The variety of configurations depends on different diameters of the wooden scatterers (i.e., 9 mm and 15 mm) and the distance between the sound source and the closest edge of the barrier (i.e., 400 mm and 800 mm). Despite having the same height (i.e., 300 mm) of a scaled model, the combination of different diameters in creating an acoustic barrier highlights an increase of the overall Insertion Loss (IL) and a broadened (instead of sharp) sound attenuation of the band gap, captured between 4 kHz and 12.5 kHz. Full article
(This article belongs to the Special Issue Recent Advances in Noise Barriers)
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18 pages, 6388 KiB  
Article
Performance of Low-Height Railway Noise Barriers with Porous Materials
by João Lázaro, Matheus Pereira, Pedro Alves Costa and Luís Godinho
Appl. Sci. 2022, 12(6), 2960; https://doi.org/10.3390/app12062960 - 14 Mar 2022
Cited by 10 | Viewed by 2725
Abstract
Rail transport is the most sustainable transportation mode, with the lowest energy consumption and carbon footprint. However, the noise induced by railway traffic in urban regions is a significant drawback and several reports point out the risks and the amount of people suffering [...] Read more.
Rail transport is the most sustainable transportation mode, with the lowest energy consumption and carbon footprint. However, the noise induced by railway traffic in urban regions is a significant drawback and several reports point out the risks and the amount of people suffering from direct exposure to railway noise. One of the most used mitigation measures for railway noise is the implementation of noise barriers. Although they offer a significant reduction in noise levels, their height makes people feel enclosed. Therefore, in the case of railway infrastructure, the solution to the problem may lie in the use of barriers with a lower height placed close to the railway track. As the noise-forming mechanisms are mainly located at the track level, placing the barrier in a position close to the track allows mitigating rail noise without causing the problems identified above for the population in the vicinity. The purpose of this paper is to illustrate the development of a barrier solution to be used in a railway context through numerical modelling with the Boundary Element Method (BEM). The solutions developed were placed close to the track and have a low height. The geometry was defined so as to direct the energy back to the track to take advantage of the acoustic properties of the ballast. The addition of a porous granular material on the inner face of the barrier allows the control of reflections between the vehicle body and the barrier, increasing its acoustic efficiency. Finally, considering the most efficient solution, the insertion loss in a network of receivers located 10 m away from the track is analysed in order to study the noise reduction levels in a place where human receivers are usually located. Full article
(This article belongs to the Special Issue Recent Advances in Noise Barriers)
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