微裂缝板吸声性能研究
Sound absorption performance of micro-ripped panel
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摘要: 宽频微穿孔板结构因面板较薄、孔径较小且穿孔率较高难以大规模推广应用, 因此提出将微穿孔板分离为支撑部件和吸声部件, 形成大孔基板复合微缝薄膜的微裂缝吸声板。理论计算了该结构的声阻抗率, 仿真分析了孔缝内外声场以及各部段的声阻抗率, 并基于仿真数据提出了考虑热黏性效应的狭长缝声阻抗末端修正模型。实验验证了微裂缝板的吸声性能, 理论、仿真和实验结果一致性良好。研究表明, 大孔基板的厚度占比较大, 声学贡献较小, 为整体结构提供了良好的支撑、通透和保护作用; 微缝薄膜的厚度占比较小, 为整体结构提供了优异的吸声功能。Abstract: A wideband micro-perforated plate (MPP) resonant absorber usually requires a combination of thin plates, minute holes and high perforation rates, which is difficult to apply on a large scale. To solve the challenge, the MPP was divided into two parts, a supporting one and a sound absorbing one. A micro-ripped panel (MRP) was formed by combining a thick baseplate with large holes and a thin film with micro rips. The acoustic impedance of the MRP was theoretically calculated. The acoustic behaviors inside and outside the aperture, and the acoustic impedance of each part of the MRP were analyzed using simulation tools. Models were established to calculate the impedance end corrections of a micro-slit with large aspect ratio considering the effect of thermal viscosity. It is found that the thick baseplate with large holes could provide good supportive, permeable, and protective effects with small acoustic contributions, and the thin film with micro rips could provide excellent sound absorption performance.