Li Xianhui
Beijing Key Laboratory of Environmental Noise and Vibration, Beijing Municipal Institute of Labor Protection, Taoranting Road 55, Beijing 100054, China.
J Acoust Soc Am. 2017 Mar;141(3):1426. doi: 10.1121/1.4976090.
Microperforated panels (MPPs) are efficient sound absorbers featuring microperforations with low porosity. Sound absorption occurs inside the perforations and their vicinity as well, which is represented with an end correction in the transfer impedance of the MPPs. Many empirical models for the end correction were derived from experiment or numerical simulation data. In order to validate these models, this paper presents an analytical solution of the end correction for sharp-edged circular perforations using viscothermal wave theory. The perforations are assumed to be periodically distributed and each perforation is associated with a square duct resulting from a periodic spatial partition. The velocity profile and the temperature field in each perforation are derived from the low reduced frequency model, which pose the boundary conditions to determine the modal coefficients of the acoustic, entropy, and viscous waves in the duct. An impedance end correction model is derived from the asymptotic expansion of the modal solution. It improves the conventional model by introducing a static flow resistance term to describe the energy dissipation due to the acoustic flow distortion outside the perforations. Numerical and experimental examples validate that the proposed model offers better prediction for the transfer impedance and the sound absorption of the MPPs.
微穿孔板（MPP）是一种高效的吸声器，其特点是具有低孔隙率的微穿孔。吸声发生在穿孔内部及其附近区域，这在MPP的传递阻抗中用端部修正来表示。许多端部修正的经验模型是从实验或数值模拟数据中推导出来的。为了验证这些模型，本文利用粘热波理论给出了锐边圆形穿孔端部修正的解析解。假设穿孔是周期性分布的，并且每个穿孔与由周期性空间划分产生的方形管道相关联。每个穿孔中的速度分布和温度场由低约化频率模型推导得出，该模型给出了确定管道中声、熵和粘性波模态系数的边界条件。从模态解的渐近展开中推导了一个阻抗端部修正模型。它通过引入一个静态流动阻力项来改进传统模型，以描述穿孔外部声流畸变引起的能量耗散。数值和实验示例验证了所提出的模型对MPP的传递阻抗和吸声具有更好的预测能力。
