An additional length model is usually used to describe the reactive part of the impedance end correction of microperforated panels, which is extended to describe the resistive part. The cross-sectional impedance is computed along the axis of one perforation cell with a circular hole. Except for the obvious jumps in the narrow regions at the inlet and outlet of the perforation, the impedance varies linearly along the axis following exactly that of the viscous wave in the circular hole. The additional length for the impedance end correction is obtained by extrapolating the linearly varying impedance inside the hole. Empirical models for the resistive and reactive additional lengths are obtained based on the thermoviscous acoustic simulation with 96 test cases. Within an error of about 10%, a unified additional length model is presented for both the resistive and reactive parts of the impedance end correction. Comparison with other existing models shows the accuracy of the proposed model.

中文翻译：

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用于微孔板的阻抗端部校正的附加长度模型。

通常使用附加长度模型来描述微孔板的阻抗端部校正的电抗部分，并扩展以描述电阻部分。横截面阻抗是沿着一个带有圆孔的穿孔单元的轴计算的。除了在穿孔的入口和出口处的狭窄区域出现明显的跳变外，阻抗沿轴的方向线性变化，并严格遵循圆孔中粘性波的阻抗。阻抗端部校正的额外长度是通过推断孔内部线性变化的阻抗得出的。基于热粘性声学模拟和96个测试案例，获得了电阻性和电抗性附加长度的经验模型。在大约10％的误差范围内，针对阻抗端部校正的电阻性和电抗性部分，提出了统一的附加长度模型。与其他现有模型的比较表明了所提出模型的准确性。