The frequency-domain linearized Navier–Stokes equations (LNSEs) are used to describe the sound field of Helmholtz resonators and concentric perforated tube resonators in the presence of low Mach number flow. The numerical procedure of LNSEs method is performed in three steps, computational fluid dynamics (CFD) calculation, data transfer and acoustics calculation. The transmission loss predictions of the resonators exhibit good agreement with measurements published in the literature. The results show that the low Mach number flow shifts the resonance frequencies of resonators and changes the acoustic attenuation behavior, which may be attributed to the change of acoustic impedance of the opening and orifices. In order to weaken the effect of flow on the resonance frequency, the modified configurations of resonators are proposed by using the conical tubes to reduce the flow velocity passing the opening and orifices. Numerical results demonstrated that the influence of flow velocity on the resonance frequency of the modified resonators is less sensitive than the original configurations.

中文翻译：

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低马赫数流下谐振器的声学行为预测与分析

频域线性化 Navier-Stokes 方程 (LNSE) 用于描述亥姆霍兹谐振器和同心穿孔管谐振器在低马赫数流下的声场。LNSEs 方法的数值过程分为三个步骤，计算流体动力学（CFD）计算、数据传输和声学计算。谐振器的传输损耗预测与文献中公布的测量值表现出良好的一致性。结果表明，低马赫数流改变了谐振器的谐振频率并改变了声衰减行为，这可能归因于开口和孔口声阻抗的变化。为了减弱流动对共振频率的影响，通过使用锥形管来降低通过开口和孔口的流速，提出了改进的谐振器配置。数值结果表明，流速对改进后的谐振器的谐振频率的影响不如原始配置敏感。