Estimating viscous losses in recycled granular microparticles: A time-domain wave decomposition impedance tube with boundary condition approximation

IF 3.4 2区物理与天体物理 Q1 ACOUSTICS

Applied Acoustics Pub Date : 2024-10-30 DOI:10.1016/j.apacoust.2024.110372

Anže Železnik, Luka Čurović, Jure Murovec, Nejc Cerkovnik, Jurij Prezelj

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引用次数: 0

Abstract

The sound absorption coefficient of a material represents the fraction of acoustic energy not reflected from its surface. The absorption is influenced by viscous losses in porous structures and sample resonances. This study proposes a novel method for measuring absorption coefficients in extended impedance tubes, specifically designed to distinguish between viscous losses and resonances, but can also be used to estimate the sound absorption coefficient in a standard impedance tube. The method is based on a time-domain wave decomposition for its simplicity of use and ability to visualize sound impulse reflections, revealing reflections of sound within the sample. A long vertical impedance tube was used to achieve sufficient separation of the sound impulses. Random noise was used as the excitation signal and spectral division deconvolution was used to calculate the sound wave impulses in the impedance tube. The proposed method was validated against the transfer function method using samples of rock wool, reconstituted foam, and polyether foam. The advantage of the proposed method was demonstrated on measurements of several granular fractions of recycled silica sand to determine the granule sizes where the main mechanism of sound absorption is viscous losses as opposed to resonances. It was found that the sound absorption caused by viscous losses is greatest for granule diameters around 500 μm.

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估算回收颗粒微粒中的粘性损失：边界条件近似时域波分解阻抗管

材料的吸声系数表示未从其表面反射的声能比例。吸声受到多孔结构中的粘性损失和样品共振的影响。本研究提出了一种测量扩展阻抗管吸声系数的新方法，专门用于区分粘性损失和共振，但也可用于估算标准阻抗管的吸声系数。该方法基于时域波分解，使用简单，能够直观地显示声脉冲反射，揭示样品内部的声反射。为了充分分离声脉冲，使用了一根长的垂直阻抗管。随机噪声被用作激励信号，频谱分割解卷积被用来计算阻抗管中的声波脉冲。利用岩棉、重组泡沫和聚醚泡沫样品，对所提出的方法与传递函数方法进行了验证。在测量回收硅砂的几种颗粒馏分以确定颗粒大小时，证明了所提方法的优势，在这些颗粒中，吸声的主要机制是粘性损失而不是共振。结果发现，颗粒直径在 500 μm 左右时，由粘性损失引起的吸声最大。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Applied Acoustics 物理-声学

CiteScore

7.40

自引率

11.80%

发文量

618

审稿时长

7.5 months

期刊介绍： Since its launch in 1968, Applied Acoustics has been publishing high quality research papers providing state-of-the-art coverage of research findings for engineers and scientists involved in applications of acoustics in the widest sense. Applied Acoustics looks not only at recent developments in the understanding of acoustics but also at ways of exploiting that understanding. The Journal aims to encourage the exchange of practical experience through publication and in so doing creates a fund of technological information that can be used for solving related problems. The presentation of information in graphical or tabular form is especially encouraged. If a report of a mathematical development is a necessary part of a paper it is important to ensure that it is there only as an integral part of a practical solution to a problem and is supported by data. Applied Acoustics encourages the exchange of practical experience in the following ways: • Complete Papers • Short Technical Notes • Review Articles; and thereby provides a wealth of technological information that can be used to solve related problems. Manuscripts that address all fields of applications of acoustics ranging from medicine and NDT to the environment and buildings are welcome.