Phong Vincent, Papamoschou Dimitri
Department of Mechanical and Aerospace Engineering, University of California, Irvine, California 92697, USA.
J Acoust Soc Am. 2015 Dec;138(6):3907-21. doi: 10.1121/1.4937602.
The transmission of sound at normal incidence through perforated plates with bias flow is investigated experimentally and theoretically over a large parameter space. A specially designed experimental apparatus enabled the measurement of insertion loss with bias flow Mach number up to 0.25. A theoretical model for insertion loss was constructed based on inviscid, one-dimensional wave propagation with mean flow through a single contraction/expansion chamber. The mass end correction of the contraction is modified for hole interaction effects and mean flow. Hydrodynamic losses are modeled using a vena contracta coefficient dependent on both perforation geometry and Reynolds number. Losses in acoustic energy that occur in the mixing region downstream of the perforations are modeled as fluctuations in entropy. The proposed model was validated experimentally over a range of plate thickness, porosity, and hole size. The experimental results indicate an increase in insertion loss with increasing frequency, followed by saturation and decline as resonant conditions are established in the perforations. The insertion loss at low frequency increases with increasing Mach number through the perforation. The proposed model captures these trends and its predictions are shown to be more accurate than those of past models.
对有偏流时垂直入射的声音通过穿孔板的传播进行了实验和理论研究，研究范围涵盖了较大的参数空间。一种专门设计的实验装置能够测量偏流马赫数高达0.25时的插入损耗。基于无粘一维波传播并考虑平均流通过单个收缩/扩张腔室，构建了插入损耗的理论模型。针对孔相互作用效应和平均流，对收缩段的质量端修正进行了改进。利用取决于穿孔几何形状和雷诺数的收缩系数对流体动力损失进行建模。穿孔下游混合区域中发生的声能损失被建模为熵的波动。所提出的模型在一系列板厚、孔隙率和孔径范围内通过实验得到了验证。实验结果表明，插入损耗随频率增加而增大，随后随着穿孔中建立共振条件而饱和并下降。低频时的插入损耗随着通过穿孔的马赫数增加而增大。所提出的模型捕捉到了这些趋势，并且其预测结果显示比以往模型更准确。
