非球形气泡的超声定量检测  

Size quantification of non-spherical bubbles by ultrasound

作　　者：张雅婧 李凡 雷照康 王铭浩 王成会[1] 莫润阳[1] Zhang Ya-Jing;Li Fan;Lei Zhao-Kang;Wang Ming-Hao;Wang Cheng-Hui;Mo Run-Yang(Shaanxi Key Laboratory of Ultrasonics,Shaanxi Normal University,Xi’an 710119,China)

机构地区：[1]陕西师范大学,陕西省超声学重点实验室,西安710119

出　　处：《物理学报》2023年第3期114-122,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12074238,11974232,11774212)资助的课题。

摘　　要：超声是检测不透明液体中气泡的有效方法,声散射模型是超声反演技术的核心.经典气泡散射模型通常是基于球形假设及ka≤1(a为气泡半径,k为入射波的波数),然而实际应用中这些假设并不总能得到满足.本研究针对非球形气泡及ka偏离假设情况,提出一种超声反演定量方案.建立不受ka约束的球形气泡级数背散射f模型,将其与经典Medwin(ka<<1)和Anderson(ka≈1)散射f模型进行对比,发现ka偏离引发的散射截面效应仅体现在散射高阶共振峰位置及大小差异上.据此提出:可通过曲线拟合法解决散射截面σ_(bs)/(πa^(2))与ka间的多值问题,同时用当量半径a^(*)对非球形气泡尺寸进行量化.具体首先利用非球形气泡背散射信号的频域信息测定其散射截面σ_(bs),再根据σ_(bs)与非球形当量半径a^(*)间拟合曲线进行反演,同时利用回波时域信息勾画气泡形状轮廓.反演结果通过高速摄影定量结果进行检验.结果表明:气泡沿之字形路径上升过程中产生非球形形变,当9≤kr_(0)≤35时,反演得到的非球形气泡当量半径与高速摄影定量半径r_(0)的相对误差小于45%,对应的最大绝对误差约为1 mm.说明该方法在一定测量精度范围可用于非球形气泡的声反演.Ultrasonic detection is an effective method to quantify bubbles in opaque liquid,and acoustic scattering model is the key in ultrasonic inversion technique.Classical scattering models are usually based on the spherical assumption,and ka is much less than 1.However,these conditions are not always satisfied in practical applications.In this study,a quantitative strategy of ultrasonic inversion is proposed for non-spherical bubbles and ka deviation assumption.A series of solution models for a spherical gas bubble is established without considering the ka constraint,and it is compared with the classical Medwin(ka<<1)and Anderson(ka≈1)models.The difference in scattering cross sectionσ_(bs)betweem them is only at the higher order formants of scattering,so the fitted line can be used to solve the multi-valued problem betweenσ_(bs)and ka.For a nonspherical bubble,σ_(bs)is determined by the frequency domain backs cat tering signal,the size is characterized by the equivalent radius a^(*),and the inversion is performed by fitted curve from series solution model.Ultrasonic quantitative results are examined by high-speed photography.Results show that during the bubbles rising along a zigzag path,they develop non-spherical bubbles,their scattering cross sections are measured by the frequency domain scattering signal obtained at a position of ultrasonic measurement,and the equivalent radius is inverted by the series solution fitting curve.The deviation of the result from the actual result r_(0)is about 1mm(relative error less than 45%)when 9≤kr_(0)≤35.This method can be used for implementing the acoustic inversion of nonspherical bubbles in a certain range of measurement accuracy.

关 键 词：超声检测 散射截面 非球形气泡 当量半径 

分 类 号：O427.4[理学—声学]