Acoustic performance of a metascreen-based coating for maritime applications

2022 ◽  
pp. 1-18
Author(s):  
Gyani Shankar Sharma ◽  
Masahiro Toyoda ◽  
Alex Skvortsov ◽  
Ian MacGillivray ◽  
Nicole Kessissoglou
Keyword(s):  
Elastic Medium ◽  
Material Properties ◽  
Sound Absorption ◽  
Numerical Models ◽  
Host Medium ◽  
Acoustic Performance ◽  
Physical Mechanisms ◽  
Cylindrical Cavities ◽  
Marine Applications ◽  
High Sound

Abstract Time and frequency domain numerical models are developed to investigate the acoustic performance of metasurface coatings for marine applications. The coating designs are composed of periodic air-filled cavities embedded in a soft elastic medium, which is attached to a hard backing and submerged in water. Numerical results for a metamaterial coating with cylindrical cavities are favourably compared with analytical and experimental results from the literature. Frequencies associated with peak sound absorption as a function of the geometric parameters of the cavities and material properties of the host medium are predicted. Variation in the cavity dimensions that modifies the cylindrical-shaped cavities to flat disks or thin needles is modelled. Results reveal that high sound absorption occurs when either the diameter or length of the cavities is reduced. Physical mechanisms governing sound absorption for the various cavity designs are described.

scholarly journals Bilayer ventilated labyrinthine metasurfaces with high sound absorption and tunable bandwidth

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiayuan Du ◽  
Yuezhou Luo ◽  
Xinyu Zhao ◽  
Xiaodong Sun ◽  
Yanan Song ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Air Flow ◽  
Single Layer ◽  
Sound Waves ◽  
Acoustic Metamaterials ◽  
Sound Barrier ◽  
Free Air ◽  
Relative Bandwidth ◽  
Wide Range ◽  
High Sound

AbstractThe recent advent of acoustic metamaterials offers unprecedented opportunities for sound controlling in various occasions, whereas it remains a challenge to attain broadband high sound absorption and free air flow simultaneously. Here, we demonstrated, both theoretically and experimentally, that this problem can be overcome by using a bilayer ventilated labyrinthine metasurface. By altering the spacing between two constituent single-layer metasurfaces and adopting asymmetric losses in them, near-perfect (98.6%) absorption is achieved at resonant frequency for sound waves incident from the front. The relative bandwidth of absorption peak can be tuned in a wide range (from 12% to 80%) by adjusting the open area ratio of the structure. For sound waves from the back, the bilayer metasurface still serves as a sound barrier with low transmission. Our results present a strategy to realize high sound absorption and free air flow simultaneously, and could find applications in building acoustics and noise remediation.

scholarly journals Mechanisms Responsible for Arc Cooling in Different Gases in Turbulent Nozzle Flow

2017 ◽  
Vol 4 (3) ◽  
pp. 234-240 ◽  
Author(s):  
Y. Guo ◽  
H. Zhang ◽  
Y. Yao ◽  
Q. Zhang ◽  
J. D. Yan
Keyword(s):  
Material Properties ◽  
High Speed ◽  
Gas Flow ◽  
Ohmic Heating ◽  
Circuit Breaker ◽  
Fault Current ◽  
High Current ◽  
Physical Mechanisms ◽  
Current Zero ◽  
Different Gases

A high voltage gas blast circuit breaker relies on the high speed gas flow in a nozzle to remove the energy due to Ohmic heating at high current and to provide strong arc cooling during the current zero period to interrupt a fault current. The physical mechanisms that are responsible for the hugely different arc cooling capabilities of two gases (SF<sub>6</sub> and air) are studied in the present work and important gas material properties controlling the cooling strength identified.

scholarly journals Fabrication of cellulose-based aerogel for thermal and acoustic insulation applications

2021 ◽  
Vol 947 (1) ◽  
pp. 012030
Author(s):  
Ngan N T Thai ◽  
Quyen N D Chau ◽  
Nam D Do ◽  
Tuan D Tran ◽  
Ha K P Huynh ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Sound Absorption ◽  
Young Modulus ◽  
High Porosity ◽  
Water Contact ◽  
Acoustic Insulation ◽  
Conductivity Water ◽  
Oil Adsorption ◽  
High Sound ◽  
Absorption Measurements

Abstract A method to prepare aerogels from rice straw and polyvinyl alcohol in the presence of fiberglass and glutaraldehyde is herein reported. The morphology, pore structure and physical properties of the aerogels were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), thermal conductivity, water contact angle (WCA) measurements, oil adsorption and sound absorption measurements. The obtained aerogels should be considered as a promising material for upcoming applications, since it has high porosity (up to 93.72%), low density (0.083-0.127 g/cm3), super low thermal conductivity (0.032-0.048 W/mK), high Young modulus (0.201-1.207 MPa), high sound absorption (absorption coefficient of 0.87) and a good oil adsorption capacity (4.8 g/g).

The Acoustic Insulation Property of a New Non-Woven Material

2011 ◽  
Vol 194-196 ◽  
pp. 471-475 ◽  
Author(s):  
Jin Jing Chen ◽  
Zheng Guo
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Nonwoven Material ◽  
Sound Absorption Coefficient ◽  
Flame Resistance ◽  
Hydrophobic Property ◽  
Insulation Property ◽  
Acoustic Insulation ◽  
High Sound ◽  
Different Thickness

The acoustic insulation and hydrophobic properties of a new non-woven material were analyzed and discussed in this paper. The new non-woven material absorbs sound energy to transfer into heat energy by friction between viscosity of air near fiber and fiber. The acoustic insulation properties of the new non-woven material, polyurethane foam and felt were measured. With the same thickness and half weight of felt, the sound absorption coefficient of non-woven was 20~30% higher than felt. Further more, with the same weight of felt, the sound absorption coefficient of non-woven was50~60% higher than felt. However, the sound absorption coefficients of non-woven materials with different thickness and weight were also discussed. The amount of the sound absorption coefficient gradient increased with the increase of thickness and frequency. Comparing the existing sound absorption materials, the new non-woven material has high sound absorption, light weight, hydrophobic property, workability, and flame resistance property. The non-woven material can improved thermal insulation and sound absorption by combining conventional non-woven with aluminum evaporated film.So the new nonwoven material has been widely applied in industries to reduce noises, especially in the car.

A Novel Thermal Insulation, Sound Absorption and Decoration Material

2011 ◽  
Vol 383-390 ◽  
pp. 3922-3928
Author(s):  
H.B. Zhu ◽  
P.M. Wang ◽  
C.S. Wang ◽  
G.T. Yan ◽  
Y.S. Cheng ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Cavity Resonator ◽  
Building Energy ◽  
Short Fiber ◽  
Building Energy Efficiency ◽  
Sound Absorber ◽  
The World ◽  
Novel Material ◽  
Heat Preservation ◽  
High Sound

Both of noise and building energy efficiency are attached importance to in the world. A novel material is developed to control noise, save building energy and decorate for buildings. Porous absorber, cavity resonator resonance sound absorber, film resonance sound absorber, functional absorber and high sound absorber are utilized to improve the sound absorbability. Perlite, Ordinary Portland cement, silicon fume, re-dispersible emulsion powder or emulsion, air-entraining agent, superplasticizer, short fiber and mesh fabrics are used to prepare novel material. Organic silicone waterproof material is used to prevent it from destroying, assist for sound absorbability and decorate for surface. After designing wedge sound absorber by mould, forming cavity resonator resonance sound absorber by air-entraining agent, and controlling compression ratio, diameter of perlite grain and cement dosage, final performances of sound absorbability and heat preservation can meet requirements of ASTM C423-84A and GB/T 20473-2006 respectively.

scholarly journals Investigation on the acoustic properties of structural gradient 316L stainless steel hollow spheres composites

2021 ◽  
Vol 28 (1) ◽  
pp. 478-488
Author(s):  
Chunhe Wang ◽  
Chunhuan Guo ◽  
Fengchun Jiang
Keyword(s):  
Stainless Steel ◽  
Sound Absorption ◽  
316L Stainless Steel ◽  
Hollow Spheres ◽  
Acoustic Properties ◽  
Casting Method ◽  
Acoustic Performance ◽  
A356 Aluminum ◽  
Different Diameters ◽  
Scanning Electron

Abstract In this study, a kind of structural gradient metal hollow spheres composites (SG-MHSCs) were fabricated using two kinds of 316L stainless steel hollow spheres with different diameters and A356 aluminum through the casting method. Then the density of the SG-MHSCs was measured by the direct measurement; the microstructure of the SG-MHSCs was characterized by the Scanning Electron Microscope. Meanwhile, the acoustic performance of MHSCs was tested by the impedance tube, and the sound absorption and insulation mechanism SG-MHSCs were discussed and analyzed.

scholarly journals Development and Investigation of Fully Ventilated Deep Subwavelength Absorbers

Symmetry ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1835
Author(s):  
Heng Wang ◽  
Qibo Mao
Keyword(s):  
Theoretical Model ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Acoustic Metamaterial ◽  
Acoustic Performance ◽  
Half Wave ◽  
Quarter Wave ◽  
New Type ◽  
Good Agreement

A new type of deep subwavelength acoustic metamaterial (AMM) absorber with 100% ventilation is presented in this study. The proposed ventilation absorber consists of coiled-up half-wave resonators (HWRs) and quarter-wave resonators (QWRs). First, the sound absorption and sound transmission performances for absorbers were analyzed considering the thermal viscosity dissipation. Then, the prototype with ten HWRs and three QWRs composed of acrylic plates was manufactured based on the theoretical model. The acoustic performance of the absorber was tested in an air-filled acoustic impedance tube to determine the sound absorption and transmission loss performances. Good agreement was found between the measured and theoretically predicted results. The experimental results show that the proposed ventilation AMM absorber is able to achieve sound absorption in a range between 330 Hz and 460 Hz with a thickness of only 32 mm (about 3% of the wavelength in the air). Furthermore, the sound transmission loss can achieve 17 dB from 330 Hz to 460 Hz. The main advantage of the proposed absorber is that it can be completely ventilated in duct noise control.

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