Visualization of acoustic radiation from a vibrating bowling ball.
Visualization of acoustic radiation from a vibrating bowling ball.
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DOI：
10.1121/1.1361059
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发表时间：
2001-06
期刊：
影响因子：
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通讯作者：
S. Wu;N. Rayess;X. Zhao
中科院分区：
文献类型：
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作者：
S. Wu;N. Rayess;X. Zhao
本文用亥姆霍兹方程最小二乘法(HELS)对振动保龄球的声辐射进行了可视化。在进行实验时，球由使用平稳随机信号的振动振动器激励。使用两个麦克风测量辐射声压，并将其作为HELS配方的输入。将重建的保龄球表面声压与相同位置测得的声压进行了比较。还显示了保龄球表面不同位置重建的声压谱与测量的声压谱的比较。结果表明，基于共形曲面测量的重建精度远高于基于有限平面的重建精度。这是因为后者经常延伸到近场区域之外，导致测量精度不一致。然而，基于声源一侧有限平面上的测量，仍然可以获得令人满意的整个保龄球表面上的声压场重建。以类似的方式重建表面速度的法向分量。一旦确定了这些声学量，就可以计算出时间平均声强。文中还给出了先验估计HELS方法所需展开函数和测量次数的公式，以及确定重建误差和最佳测量位置的准则，给出了震源的总体尺寸和重建中感兴趣的最高频率。
This paper presents visualization of acoustic radiation from a vibrating bowling ball using the Helmholtz equation least squares (HELS) method. In conducting the experiments, the ball is excited by a vibration shaker using stationary random signals. The radiated acoustic pressures are measured using two microphones and taken as input to the HELS formulations. The reconstructed acoustic pressures on the bowling ball surface are compared with those measured at the same locations. Also shown are comparisons of the reconstructed and measured acoustic pressure spectra at various locations on the bowling ball surface. Results demonstrate that the accuracy of reconstruction based on measurements over a conformal surface is much higher than that over a finite planar surface. This is because the latter often extends beyond the near-field region, making the accuracy of measurements inconsistent. Nevertheless, satisfactory reconstruction of acoustic pressure fields over the entire bowling ball surface can still be obtained based on the measurements taken over a finite planar surface on one side of the source. In a similar manner, the normal component of the surface velocity is reconstructed. Once these acoustic quantities are determined, the time-averaged acoustic intensity is calculated. Also presented are the formulations for estimating a priori the numbers of expansion functions and measurements required by the HELS method and the guidelines for determining the reconstruction error and optimum measurement locations, given the overall dimensions of the source and the highest frequency of interest in reconstruction.