On the acoustic effects of sonic crystals in heat exchanger arrangements

Czwielong, Felix; Hruška, Viktor; Bednařı́k, Michal; Becker, Stefan

doi:10.1016/j.apacoust.2021.108253

Cited by 11 publications

(3 citation statements)

References 35 publications

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“…The aerodynamic performance and the noise emission of the axial fans were measured in the axial test bench at the Friedrich-Alexander University Erlangen-Nuremberg [15,25]. The inflow turbulence necessary for the investigation of turbulence interaction noise was generated by a turbulence grid, which was mounted 65 mm upstream of the axial fans in a short duct.…”

Section: Methodsmentioning

confidence: 99%

Aerodynamic and aeroacoustic properties of axial fan blades with slitted leading edges

et al. 2022

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A detailed experimental analysis of the aerodynamic and aeroacoustic properties of flat-plate axial fans with slitted leading edges is performed. The sound emissions of five slitted leading edge designs are measured at a constant rotational speed and at a constant total-to-static pressure rise of the fans. For both cases, the fan blades with slitted leading edges reduce the turbulence interaction noise and lead to a reduction of the overall sound pressure level for volume flow rates above 0.6 m3 s−1 compared to an axial fan with solid leading edges. The far-field noise analysis shows that the slits result in a noise reduction for frequencies below 2 kHz and a noise increase above 2 kHz. In addition, sound source localization is conducted with a microphone array and rotating beamforming methods are applied. The identified sound source distributions prove that slitted leading edges reduce turbulence interaction noise, but generate broadband noise in the fan blades’ trailing edge regions. The maximum sound reduction due to the slits could be detected at a dimensionless frequency of $ fh/\bar{w}\approx 0.5$, where f is the frequency, h is the height of the slit and $ \bar{w}$ is the mean relative inflow velocity. The noise reduction mechanism on axial fan blades corresponds well to previous investigations on flat-plate airfoils with slits.

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Section: Methodsmentioning

confidence: 99%

Aerodynamic and aeroacoustic properties of axial fan blades with slitted leading edges

et al. 2022

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“…At some frequency, the results of numerical calculating with non-real scale calculating diverge quite a bit [18]. The use of sonic crystals has enabled noise from the room heater to be reduced and the sound level to be lowered by 10 dB [19]. To the author's knowledge, there isn't currently a sonic crystal that can be used directly on highways to lessen traffic noise.…”

Section: Introductionmentioning

confidence: 99%

Use of sound attenuation with sonic crystal structures in residential areas due to highways

Handayani

2023

J Appl Eng Science

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Indonesia is a growing nation that needs assistance placing structures beside roadways. Ideally, one should place buildings along residential roads rather than main or collector highways. Due to the high levels of vehicular noise pollution on Indonesian arterial and collector roads, many buildings are located alongside them. This negatively impacts both the environment and human health. As a result, efforts must be made to reduce noise, and one such endeavor is the construction of noise-absorbing structures. Walls are commonplace, noise-absorbing structures with low sound-absorption capacities and fewer aesthetic drawbacks. Sonic crystals are a novel method of noise reduction. This study aims to evaluate the effectiveness of sonic crystals and their possible application in residential areas to reduce noise from the roads. Tests were carried out in an outdoor setting using a real scale. By describing the sonic crystal, it is possible to determine quantitatively how much sound it can absorb. It is also possible to obtain the sound's shapes that sonic crystals can attenuate. The findings indicate that the maximum IL value is 21.57 dB, and the average IL value is 16.90 dB. The area that the sonic crystal attenuates enough is about 3 meters after the crystal and roughly 2 meters from the crystal's center axis, respectively. These findings concern using sonic crystals to lessen noise from traffic in residential areas.

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“…Based on these variables, the idea of creating sound crystals is extensive and requires many test samples [44].…”

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confidence: 99%

Resonant Acoustic Metamaterials

Iannace,

Amadasi,

Bevilacqua

et al. 2024

Applied Sciences

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Acoustic applications of metamaterials have rapidly developed over the past few decades. The sound attenuation provided by metamaterials is due to the interaction between soundwaves and scatterers organized into a reticular grid, with a peak attenuation at a specific frequency band that is highly dependent on the scatterers’ diameter and reticular geometric organization of installation. In this article, the scatterer types chosen for the experiments are represented by a 2D shape, which are cylindrical solid-wood bars of 15 mm diameter and empty cylindrical bars of 20 mm diameter. Acoustic measurements were conducted in a semi-anechoic chamber to identify the specific frequency at which the highest insertion loss (IL) was registered. A second experiment was conducted by creating holes of 5 mm diameter on the external surface of the empty bars; in this way, it registered a higher sound attenuation. In particular, the resonant system characterized with holes, in combination with the attenuation given by 2D scatterer metamaterials, increased the sound attenuation for the frequency range between 1 kHz and 10 kHz.

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On the acoustic effects of sonic crystals in heat exchanger arrangements

Cited by 11 publications

References 35 publications

Aerodynamic and aeroacoustic properties of axial fan blades with slitted leading edges

Aerodynamic and aeroacoustic properties of axial fan blades with slitted leading edges

Use of sound attenuation with sonic crystal structures in residential areas due to highways

Resonant Acoustic Metamaterials

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