The sound transmission loss across a duct muffler in the form of a linear array of 11 narrow sidebranches is examined experimentally in the present study. The introduction of a low Mach number duct flow deteriorates the broadband acoustical performance of the muffler and strong sound transmission loss dips and sound amplifications are observed at high flow speeds. It is found that a stronger acoustic pressure magnitude inside the sidebranches improves the muffler's performance in the presence of the duct flow. A theoretical analysis using a 2-sidebranch array muffler is conducted and the results indicate the possibility of increasing the sound pressures inside the sidebranches by locating the shorter sidebranch upstream of the longer one. The results of further experiments validate the theoretical deduction. Results also confirm that the muffler with sidebranches arranged in the order of decreasing acoustic impedance magnitude has stronger resilience against aerodynamic disturbance and gives better performance when the upstream excitation level and the duct flow speed are fixed.

中文翻译：

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在低马赫数下通过狭窄的侧枝阵列风道消声器进行声音传输

在本研究中，通过实验检查了通过11个窄侧支的线性阵列形式的管道消声器的传声损失。低马赫数的管道流的引入使消声器的宽带声学性能恶化，并且在高流速下观察到强烈的声音传输损耗下降和声音放大。已经发现，在存在管道流的情况下，侧支管内部的声压强度越大，则消声器的性能越好。进行了使用2个侧分支阵列消声器的理论分析，结果表明，通过将较短的侧分支放置在较长侧分支的上游，可以增加侧分支内部的声压。进一步的实验结果验证了理论推论。