Improvements to the methods used to measure bubble attenuation using an underwater acoustical resonator.
Improvements to the methods used to measure bubble attenuation using an underwater acoustical resonator.
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DOI：
10.1121/1.3569723
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发表时间：
2011-11
期刊：
影响因子：
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通讯作者：
H. Czerski;S. Vagle;D. Farmer;N. Hall-Patch
中科院分区：
文献类型：
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作者：
H. Czerski;S. Vagle;D. Farmer;N. Hall-Patch
主动声学技术通常用于测量海洋气泡尺寸分布，通过反演水的整体声学特性（通常是衰减）来推断气泡数量。声学谐振器以前曾用于在单次测量中确定宽频率范围（10-200 kHz）的衰减，对应于宽范围气泡尺寸（20-300 μm半径）的同时测量。然而，现在也有相当大的兴趣，在获得测量的气泡半径小于16微米，因为这些被认为是重要的海洋光学和示踪剂的近表面流。为了将气泡数量测量扩展到更小的半径，有必要将衰减测量扩展到更高的频率。虽然谐振器的工作原理不会随着频率的增加而改变，但是在频谱分析期间先前做出的假设可能不再有效。为了改进用于从声学谐振器输出计算衰减的方法，本文提出了比先前发表的更完整的谐振器操作分析。这种方法允许在更宽的频率范围内进行鲁棒的衰减测量，并能够从较低质量的频谱峰值进行精确测量。
Active acoustic techniques are commonly used to measure oceanic bubble size distributions, by inverting the bulk acoustical properties of the water (usually the attenuation) to infer the bubble population. Acoustical resonators have previously been used to determine attenuation over a wide range of frequencies (10-200 kHz) in a single measurement, corresponding to the simultaneous measurement of a wide range of bubble sizes (20-300 μm radii). However, there is now also considerable interest in acquiring measurements of bubbles with radii smaller than 16 μm, since these are thought to be important for ocean optics and as tracers for near-surface flow. To extend the bubble population measurement to smaller radii, it is necessary to extend the attenuation measurements to higher frequencies. Although the principles of resonator operation do not change as the frequency increases, the assumptions previously made during the spectral analysis may no longer be valid. In order to improve the methods used to calculate attenuation from acoustical resonator outputs, a more complete analysis of the resonator operation is presented here than has been published previously. This approach allows for robust attenuation measurements over a much wider frequency range and enables accurate measurements from lower-quality spectral peaks.