Beam Behavior within the Nearfield of a Vibrating Piston
Beam Behavior within the Nearfield of a Vibrating Piston
复制标题
振动活塞近场内的梁行为
DOI：
10.1121/1.1912316
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发表时间：
1971
影响因子：
2.4
通讯作者：
J. Zemanek
中科院分区：
文献类型：
--
作者：
J. Zemanek
对振动活塞的近场区域进行了数值研究。虽然现有的文献并不完全清楚规则波束图案形成的距离有多近，但这项研究的结果显示了人们可以预期的操作极限。根据文献的一种解释，具有等于换能器直径的最小光斑尺寸的−3db波束应该形成超过轴向距离z=3.89a2/λ。研究表明，这种光束在z=0.75a2/λ处形成，其最小光斑尺寸等于换能器半径的四分之一。这些结果在a/λ‘S为1~20的换能器上得到了验证，并且可以放心地推广到更高的a/λ’S。对于−1.5-、−4.5-、−6.0-、−7.5-、−9.0-、−10.5-和−12-分贝波束也得到了类似的结果。
A numerical investigation of the nearfield region of a vibrating piston was conducted. While existing literature is not exactly clear about how close to a transducer a regular beam pattern is formed, the results of this investigation show the limits of operation one can expect. From one interpretation of literature, a −3‐dB beam with a minimum spot size equal to the transducer diameter would be expected to form beyond an axial distance z = 3.89 a2/λ. This investigation shows that such a beam forms at z = 0.75 a2/λ and has a minimum spot size equal to one‐quarter the transducer radius. These results are verified for transducers with a/λ's ranging from 1 to 20 and can be extended with confidence to higher a/λ's. Similar results are also obtained for −1.5‐, −4.5‐, −6.0‐, −7.5‐, −9.0‐, −10.5‐, and −12‐dB beams.