Source visualization by using statistically optimized near-field acoustical holography in cylindrical coordinates
Source visualization by using statistically optimized near-field acoustical holography in cylindrical coordinates
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DOI：
10.1121/1.2036252
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发表时间：
2005-10-01
影响因子：
2.4
通讯作者：
Hald, J
中科院分区：
文献类型：
--
作者：
Cho, YT;Bolton, JS;Hald, J
近场声全息术（NAH）对于可视化噪声源也很有用。然而，为了避免空间傅里叶变换相关的截断效应，测量或全息图表面必须延伸到声源之外的区域，在该区域声压下降到显著低于测量孔径内的峰值水平。统计优化的近场声全息（SONAH），首先由Steiner和Hald在平面几何中导出，是基于类似于NAH的公式。然而，在SONAH中，声场的表面到表面投影是通过使用传递矩阵来执行的，该传递矩阵以使得所有传播波和一组加权的倏逝波以最佳平均精度投影的方式来定义：即，不执行空间傅立叶变换。因此，消除了测量表面延伸的要求，而不损害过程的准确性。在本工作中，SONAH重新制定了圆柱坐标系，并应用于测量的辐射声场的制冷压缩机。结果发现，它是可能的，通过使用SONAH精确地可视化源区域，同时使用更少的测量位置比将需要实现类似的精度水平时，使用传统的NAH程序。(c)2005年美国声学学会。
Nearfield acoustical holography (NAH) is a useful too] for visualizing noise sources. However, to avoid spatial Fourier transform-related truncation effects, the measurement, or hologram, surface must extend beyond the source to a region where the sound pressure drops to a level significantly lower than the peak level within the measurement aperture. Statistically optimized nearfield acoustical holography (SONAH), first derived by Steiner and Hald in planar geometry, is based on a formulation similar to that of NAH. However, in SONAH, Surface-to-surface projection of the sound field is performed by using a transfer matrix defined in such a way that all propagating waves and a weighted set of evanescent waves are projected with optimal average accuracy: i.e., no spatial Fourier transforms are performed. Thus the requirement that the measurement surface be extended is eliminated without compromising the accuracy of the procedure. In the present work, SONAH was re-formulated in cylindrical coordinates and was applied to the measurement of the sound field radiated by a refrigeration compressor. It was found that it is possible to visualize source regions accurately by using SONAH while using fewer measurement positions than would be required to achieve a similar level of accuracy when using conventional NAH procedures. (c) 2005 Acoustical Society of America.