Abstract Noise from jet engines can be reduced by means of a Helmholtz cavity configuration. The resonance that occurs when a flow passes the neck of the Helmholtz resonator will dissipate acoustic energy. The mechanism for such dissipation is mainly due to the vortex shedding that occurs at the neck of the resonator where the vortex structures absorb acoustic energy and subsequently dissipate it through viscous effects. In this work, numerical simulations utilizing the lattice Boltzmann method are used to aid in visualizing the flow behaviour that is associated with Helmholtz cavity-backed acoustic liners. In both experiments and numerical simulations, the 1-neck cavity is found to result in an amplification of an applied acoustic source. For a 4-neck cavity, the configuration is able to achieve acoustic pressure reductions. Differences in the flow behaviour of the 1-neck and 4-neck cavities are detailed in this work. Results show that the stronger vortex shedding that occurs in the 4-neck cavity configuration could explain its increased effectiveness as a Helmholtz cavity-backed acoustic liner. Graphic Abstract

中文翻译：

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与亥姆霍兹背腔声学衬垫相关的流动行为的格子 Boltzmann 模拟

摘要 喷气发动机的噪声可以通过亥姆霍兹腔结构来降低。当流动通过亥姆霍兹共振器的颈部时发生的共振将耗散声​​能。这种耗散的机制主要是由于在谐振器颈部发生的涡流脱落，涡流结构吸收声能并随后通过粘性效应将其耗散。在这项工作中，利用格子 Boltzmann 方法的数值模拟用于帮助可视化与亥姆霍兹空腔背衬声学衬垫相关的流动行为。在实验和数值模拟中，发现 1 颈腔会导致应用声源的放大。对于 4 颈腔，该配置能够实现声压降低。在这项工作中详细介绍了 1 颈和 4 颈腔的流动行为的差异。结果表明，在 4 颈腔配置中发生的更强的涡旋脱落可以解释其作为亥姆霍兹空腔背衬声学衬垫的有效性增加。图形摘要