Numerical and Experimental Investigations of Modal Coherence Characteristics for the Determination of Broadband Noise in Flow Ducts
Numerical and Experimental Investigations of Modal Coherence Characteristics for the Determination of Broadband Noise in Flow Ducts
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DOI：
10.3389/fenrg.2022.873749
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发表时间：
2022-03
期刊：
影响因子：
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通讯作者：
Kunbo Xu;Cunliang Liu;Fan Tong;W. Qiao
中科院分区：
文献类型：
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作者：
Kunbo Xu;Cunliang Liu;Fan Tong;W. Qiao
本文详细地研究了非线性噪声的模态相干特性。通过建立三种管道声源分布模型，研究了管道噪声高频模态相干特性。计算结果与单级轴流风扇的声学实验结果一致。结果表明，不同阶次的声模是互不相干的，同一周向模内的径向模具有很大的相干性。本文成功地利用旋转传声器阵列对汽车噪声进行了声学测量。声学实验结果表明，某些模态的相干性对入射声波在流道中的测量影响不大，但对反射模态声功率的预测会产生约3 dB的偏差，对反射声波的频谱形状影响不大。结果表明，实验测得的模式相干函数给出了一个内在的意义上的空间噪声源分布，并使传播内的模式散射的调查。基于本文所得到的模态相干特性，可以为超宽带噪声测试进行更多的理论和方法研究。
This paper presents a detailed investigation about the modal coherence characteristics of turbomachinery noise. The modal coherence characteristics of ducted noise at high frequencies are investigated by establishing three kinds of ducted sound source distribution models. The results are consistent with the acoustic experimental results of a single-stage axial fan. The results show that acoustic modes of different orders are mutually incoherent, and radial modes within the same circumferential mode have a great degree of coherence. This paper successfully conducted an acoustic measurement on turbomachinery noise by rotating microphone arrays. The acoustic experimental results show that the coherence of some modes has little impact on the measurement of incident acoustic waves in the flow duct, while it leads to about 3 dB deviation in the prediction of the reflected modal sound power and has little influence on the spectral shape of reflected acoustic waves. It was demonstrated that the experimentally measured modal coherence functions give an inner sense of the spatial noise source distribution and enable the investigation of mode scattering within the propagation. Based on the modal coherence characteristics obtained in this paper, more theoretical and methodological studies can be carried out for the turbomachinery broadband noise test.