金属纤维多孔材料在高声强下的吸声性能研究
文献类型：学位论文
| 作者 | 常宝军 |
| 学位类别 | 博士 |
| 答辩日期 | 2009-05-31 |
| 授予单位 | 中国科学院声学研究所 |
| 授予地点 | 声学研究所 |
| 关键词 | 金属纤维多孔材料 非线性静流阻 高声强 吸声性能优化 |
| 其他题名 | Investigation on Sound Absorption Performance of Fibrous Porous Metals at High Sound Pressure Levels |
| 学位专业 | 声学 |
| 中文摘要 | 金属多孔材料具备轻质，耐热、耐腐蚀等多功能特性，通过合理设计，可实现宽频带、高吸声的优良特性。在一些极端条件如高温、高声强环境下的噪声控制方面，还有着十分良好的应用潜力。基于多孔金属材料在航空发动机声衬的潜在应用以及目前尚未见有纤维材料参数对高声强吸声性能影响的研究，本文以金属纤维多孔材料在高声强环境的应用为背景，对其吸声特性进行理论与实验研究。主要工作如下： （1） 针对高孔隙率的金属纤维多孔材料，在不可压的流动状态方程中引入线化的惯性项，并通过渐进匹配方法得到半经验的非线性流阻模型。分析得到线性静流阻随丝径的增大而减小，非线性系数随丝径的增大而增大的结论。再结合高声强模型得到金属纤维多孔材料在高声强下的吸声性能。 （2） 在静流阻测试系统中，得到了实际金属纤维多孔材料静流阻的实验结果，与理论预测结果比较符合，由此验证了本文推导非线性流阻模型的方法的可行性；在阻抗管测试系统中，得到了材料法向表面阻抗和吸声系数随入射声压级变化的实验结果，与理论预测结果符合良好，由此进一步验证了本文推导的预测方法的可行性。 （3） 针对金属纤维多孔材料结构，研究了材料的流阻特性、声阻抗特性和色散特性，得出了材料内部等效声速随线性静流阻的增大而减小，衰减系数随非线性系数增大而增大的规律。分析了各基本材料参数与表面法向入射声阻抗的关系：材料声阻随纤维直径增大而减小，而声抗增大；材料声阻随孔隙率的增大而减小，而声抗增大。根据材料各参数和表面声阻抗的关系，提出了通过设计材料各基本参数提高材料在高声强条件下单频和离散宽频吸声性能的设计准则。 |
| 英文摘要 | Porous metals have characteristics such as light-weight, both heat and corrosion resistance. They can absorb sound at a wide band of frequencies after optimizing their material structure. Because of these advantages, porous metals have potentials in noise control, especially under some adverse conditions, such as intense heat and high sound intensities. One such potential application is for aircraft engine liners, but how the material parameters affect the sound absorption at high sound intensities is still unclear. Therefore, this dissertation aims at addressing this problem, i.e. the absorption performance of fibrous porous metals at high sound pressure levels, both theoretically and experimentally. The main contents are as follows: (1) A method is proposed to derive the nonlinear coefficient in the flow resistivity relation for highly porous fibrous metals, by retaining inertia terms in the incompressible flow equations. A semi-empirical model is obtained in this thesis. Conclusions are obtained that with increasing the fiber diameter the linear flow resistivity decreases and the nonlinear parameter increases. Based on this, nonlinear sound absorption performance can be predicted by employing an acoustical model for sound absorption at high sound pressure levels. (2) Static flow resistivities were measured in a flow resistivity testing rig. The experiments agree with our theoretical prediction. Sound absorption performance at various sound pressure levels was measured in an impedance tube by the transfer-function method. The results also agree with our theoretical prediction. The sound absorption mechanism of fibrous materials is then briefly analyzed. (3) The flow resistivity, the surface sound impedance and frequency dispersive properties are analyzed. Conclusions about acoustic propagation characteristics are obtained that the sound velocity in the material decreases with increasing the linear flow resistivity; the attenuation coefficient increases with increasing the nonlinear parameter. The relationship between parameters of fibrous metals, sound pressure levels and surface acoustic impedances is also analyzed. A design method is proposed to optimize the absorption performance, with a few design guides for both pure single frequencies and broadband discrete frequencies.at high sound pressure levels. |
| 语种 | 中文 |
| 公开日期 | 2011-05-07 |
| 页码 | 99 |
| 源URL | [http://159.226.59.140/handle/311008/580]  |
| 专题 | 声学研究所_声学所博硕士学位论文_1981-2009博硕士学位论文 |
| 推荐引用方式 GB/T 7714 | 常宝军. 金属纤维多孔材料在高声强下的吸声性能研究[D]. 声学研究所. 中国科学院声学研究所. 2009. |
入库方式： OAI收割
来源：声学研究所
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