盲通分支管流致声共振压力脉动传播数值研究

Numerical Investigation of Pressure-Fluctuation Propagation in Flow-Induced Acoustic Resonance of Blind Branches

摘要: 在管路系统中，由主管道与盲通分支管组合结构流致声共振引起的压力脉动会沿主管道上、下游传播。然而，不同分支管结构对压力脉动传播特性的影响尚不明确。本文采用大涡模拟对单盲通分支管与对称盲通分支管内流致声共振进行了数值模拟，并结合动态模态分解方法分析了空间传播特性。结果表明：单盲通分支管与对称盲通分支管在流致声共振下的压力脉动传播特性存在显著差异。单盲通分支管内压力脉动受分支管一阶声学模态控制，并沿主管道上、下游传播。而对称盲通分支管改变了主管道内压力脉动的频率组成，表现为一阶声学模态与次频共同作用，其一阶声学模态频率为流场主要脉动成分，次频及二阶声学模态来源于流动非线性作用下的流声耦合机制，并促进压力脉动由分支管向主管道传播。这些研究结果为特定工况下复杂管路系统压力脉动传播特性提供了初步认识，并为后续结构优化研究提供参考。

Abstract: In piping systems, pressure fluctuations induced by flow-induced acoustic resonance in combined main-duct and blind-branch configurations can propagate both upstream and downstream along the main duct. However, the influence of different branch configurations on the propagation characteristics of pressure fluctuations remains unclear. In this study, large-eddy simulations were performed to investigate flow-induced acoustic resonance in single and symmetric blind-branch configurations, and dynamic mode decomposition was employed to analyze the spatial propagation characteristics of pressure fluctuations. The results demonstrate significant differences in the pressure-fluctuation propagation behaviors between the two configurations. For the single blind branch, the pressure fluctuations are primarily governed by the first-order acoustic mode of the branch and propagate along the upstream and downstream directions of the main duct. In contrast, the symmetric blind-branch configuration modifies the frequency composition of pressure fluctuations in the main duct, exhibiting a propagation behavior jointly influenced by the first-order acoustic mode and higher-frequency components. The first-order acoustic mode represents the dominant fluctuation component of the flow field, while the higher-frequency components and the second-order acoustic mode originate from nonlinear aeroacoustic coupling and facilitate the propagation of pressure fluctuations from the branches into the main duct. These findings provide preliminary insights into pressure-fluctuation propagation characteristics in complex piping systems under specific operating conditions and offer a reference for further structural optimization studies.