【作者】 杨东；

【导师】 朱民；

【作者基本信息】 清华大学 ， 动力工程及工程热物理， 2013， 硕士

【摘要】 亥姆霍兹共振器是简单常用的吸声装置。在本文涉及的工作中，为了同时改善亥姆霍兹共振器的共振吸声系数和整体吸声带宽，我们将具有不同穿孔直径的平行穿孔材料安装在共振器颈部，通过这些穿孔材料来优化共振器的颈部入口声阻抗并最终优化共振器的吸声效果。基于Forchheimer非线性关系，我们发展了一个计算共振器入口声阻抗的理论模型。并且，通过一套静流阻测量系统测量了不同穿孔材料的静流阻率非线性系数，并由此计算出了亥姆霍兹共振器入口的非线性声阻抗。与此同时，我们利用声学管道实验台，实验测量了颈部安装不同穿孔直径材料的共振器的吸声系数。通过理论和实验对比发现，在共振器共振频率附近，穿孔材料中管流非充分发展效应对共振器入口声阻抗的非线性有着不可以忽略的影响。将考虑非线性修正后的理论声阻抗计算值带入管道系统吸声系数理论模型中，发现理论预测和实验结果符合得很好。最后，根据这些理论和实验基础，我们得到了最优的颈部材料穿孔孔径。更多还原

【Abstract】 Helmholtz resonators are widely used as sound absorption devices for their simple aswell as efective sound absorption performance. To improve Helmholtz resonators’ reso-nance sound absorption coefcient and their sound absorption bandwidth simultaneously,sound absorption materials were used to fill the resonators’ neck. In this work, paral-lel perforated ceramics with diferent perforation diameters were installed into the neckof a Helmholtz resonator to improve its acoustic impedance to simultaneously achieve abetter acoustic absorption coefcient and a wider absorption bandwidth. A model of theneck mouth impedance is developed based on the nonlinear Forchheimer relationship. Asystem to measure the static resistivity is used to specify the non-fully developed factorand the Forchheimer coefcient for neck materials with diferent perforation diameters.An experimental system was built to investigate the efect of the perforation diameters onthe sound absorption performance of the resonator. It is found that nonlinear efects nearthe resonance frequency caused by non-fully developed pipe flow cannot be neglected.The experimental results are in good agreement with the theoretical model. Then we gotthe optimal perforation diameter of the neck materials.更多还原