变截面管道流噪声数值计算

采用变分形式的Lighthill声类比方程来定量地求解管路内流噪声。数值计算主要分为两步:第一步通过精细的流场网格计算非定常的噪声源;第二步将声源结果守恒插值至声学网格,并通过有限元法计算声传播。在非定常流场计算中采用大涡模拟(LES)湍流模型,以获取噪声源。与试验值对比发现数值计算结果与试验结果趋势一致,从而验证了计算结果的合理性。研究结果表明,在分析原截面突缩管的主要噪声源分布后,优化管截面获得很好的降噪效果。

Numerical Simulation of Flow-induced Noise in the Pipelines with Variable Cross-sections

The main attention of the present work is paid to the numerical simulation of flow-induced noise quantitatively using the variational formulations of Lighthill’s acoustic analogy. The flow-induced noise is computed in a coupled two-step procedure. First of all, results from an unsteady flow simulation capable to resolve the turbulent scales responsible for the noise generation are used to compute acoustic source terms directly on the fine fluid grid. As a second step, after conservative interpolation of the acoustic nodal sources to the acoustic grid, the acoustic propagation is computed using the Finite Element method(FEM). Unsteady flow computations following LES turbulence modeling approaches are used for the evaluation of the acoustic sources. For the validation of the numerical results of the acoustic pressure for the variable cross-sectional pipes, numerical results are consistent with the corresponding measured data. It is indicated that after analyzing the distribution of the acoustic source magnitude in the sudden area contraction pipe, the proposed optimized models obtain well performance of reducing noise.