Abstract The perforated components are widely used in the intake and exhaust mufflers. The coupling between instable shear layer and acoustic fluctuation has a significant influence on the acoustic impedance of perforated components. To obtain practical and precise acoustic impedance of perforated plates in the presence of grazing flow, the three-dimensional (3D) time-domain computational fluid dynamics (CFD) approach was employed in the present study, and the extraction method of acoustic impedance was presented. The predicted non-dimensional acoustic impedance of the rectangular slot is consistent with the previous published measurement, which validates the accuracy of the present approach. Characterization of the turbulent boundary layer of flat-plate flow was studied and the relation between the convection velocity of vorticity and mean grazing flow velocity was provided. Numerical evaluations were carried out for different mean grazing flow Mach number Mmean (0.05–0.20), thickness to diameter ratio of orifice t/dh (0.2–0.5), porosity ϕ (4.51%–24.93%), and Reynolds number Re resulted from the orifice diameter dh (2 mm–6 mm), and their effects on the non-dimensional acoustic impedance of circular orifice were investigated in detail. The acoustic impedance formulae are obtained using the piecewise numerical fitting method based on the parameter analyses. As an application of engineering computation, the transmission loss of straight-perforated tube mufflers was predicted by using the present acoustic impedance model and the empirical impedance model of Lee and Ih via finite element computations. Comparison of the predicted and measured transmission loss (TL) results demonstrates that the present model yields highly accurate prediction.

中文翻译：

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存在完全发展的掠流时穿孔板的声阻抗

摘要 穿孔部件广泛应用于进排气消声器中。不稳定剪切层与声波涨落的耦合对穿孔构件的声阻抗有显着影响。为了在掠流存在下获得实用且精确的穿孔板声阻抗，本研究采用三维（3D）时域计算流体动力学（CFD）方法，并提出了声阻抗的提取方法. 矩形槽的预测无量纲声阻抗与先前公布的测量结果一致，这验证了本方法的准确性。研究了平板流湍流边界层的特征，给出了涡度对流速度与平均掠流速度之间的关系。对不同的平均掠流马赫数 Mmean (0.05–0.20)、孔口厚径比 t/dh (0.2–0.5)、孔隙率 ϕ (4.51%–24.93%) 和雷诺数 Re 进行了数值评估详细研究了孔口直径 dh (2 mm–6 mm) 及其对圆形孔口无量纲声阻抗的影响。声阻抗公式是在参数分析的基础上，采用分段数值拟合的方法得到的。作为工程计算的应用，直穿孔管消声器的传输损失是通过使用现有的声阻抗模型和 Lee 和 Ih 的经验阻抗模型通过有限元计算来预测的。预测和测量的传输损耗 (TL) 结果的比较表明，本模型产生了高度准确的预测。