基于混合方法的膨胀腔非稳态流动及气动噪声分析

采用混合方法对气流作用下的膨胀腔的非稳态流动和气动噪声进了数值仿真分析。建立基于有限体积法的流体仿真模型，采用大涡模拟方法对膨胀腔内部非稳态流动进行计算。数值仿真结果捕捉到了腔体内部非稳态流动以及涡量的发展变化过程，并与实验观测结果基本吻合。采用积分插值的方法将流场结果插入声学网格上，基于气动声学理论计算腔体内部的流噪声源。建立声学仿真模型，将流噪声源导入声场网格中计算远场响应点的声压，并与实验结果进行对比，声压级以及共振频率都吻合良好。结果表明:混合仿真方法准确直观揭示出管内流噪声产生的机理和过程，尾管辐射噪声的仿真结果与实验结果及理论计算结果的偏差都在5%以内。 

Unsteady flow field and flow-induced noise analysis forexpansion chambers based on hybrid method

The unsteady flow field and flow-induced noise of the expansion chamber under the effect of airflow were numerically simulated and analyzed based on hybrid method. The simulation model based on the finite volume method was established, and the large eddy simulation method was used to calculate the unsteady flow in the expansion cavity. The numerical simulation successfully captured the unsteady flows and the development of eddies in the internal cavity, and agreed well with the experiment results. The flow field results were inserted into acoustic mesh by the integral interpolation method, and then the flow-induced noise sources were calculated by the aeroacoustics theory. The flow-induced noise sources were imported to the acoustic simulation model to calculate the sound pressure at the response points. The acoustic simulation results agreed well with the experiment results on the sound pressure level and resonance frequencies. The results showed that the hybrid method combined the large eddy simulation and the aeroacoustics theory, and revealed the mechanism and process of the flow-induced noise generation in the expansion chamber accurately. The deviations of the tail pipe radiated noise between the simulation results and the experimental results, as well as the theoretical calculation results, were within 5%.