Yu Jiawen, Yang Desen, Zhang Jiangyi
National Key Laboratory of Underwater Acoustic Technology, Harbin Engineering University, Harbin 150001, China; Key Laboratory of Marine Information Acquisition and Security(Harbin Engineering University), Ministry of Industry and Information Technology; Harbin 150001, China; College of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001, China.
National Key Laboratory of Underwater Acoustic Technology, Harbin Engineering University, Harbin 150001, China; Key Laboratory of Marine Information Acquisition and Security(Harbin Engineering University), Ministry of Industry and Information Technology; Harbin 150001, China; College of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001, China.
Ultrason Sonochem. 2023 Dec;101:106699. doi: 10.1016/j.ultsonch.2023.106699. Epub 2023 Nov 22.
We study theoretically and numerically sound attenuation in bubble-containing media when the bubbles are freely oscillating at high Mach numbers. This paper expands one of the main forms of bubble-related acoustic damping factors by extending the previous theories to higher Mach numbers, further improves the theories of nonlinear sound propagation in bubble-containing media. A nonlinear sound propagation model incorporating second-order liquid compression terms is developed, expressing the sound velocity and density in the medium as a function of the driving pressure, and taking into account the higher-order liquid compression effects on sound propagation. The correctness of the proposed model is verified by comparing with a linear model and a nonlinear model containing only low-order Mach number terms. When the bubble oscillates at a high Mach number, radiation damping, which is directly related to Mach number, becomes the main damping component affecting sound attenuation. The higher the driving amplitude, the stronger the nonlinear effect, and the greater the impact of high-order liquid compression effects on the sound attenuation, the more necessary it is to use the proposed model to calculate the sound attenuation. For high Mach numbers, varying the bubble radius and bubble number density, respectively, the difference between the proposed model and the model containing only low-order Mach number terms in capturing the pressure-dependent attenuation is calculated. Due to stronger radiation damping in smaller bubbles, the effect of compressibility becomes more important. The smaller the bubble radius, the greater the half-quality factor of the curve related to the difference in attenuation calculated by the two models, the more necessary it is to calculate the pressure-dependent attenuation using the proposed model. Here, the half-quality factor is defined as the corresponding frequency bandwidth when the curve falls from the maximum value to 22 times. Without considering the coupling effect between bubbles, the half-quality factor of the curve is not affected by the bubble number density.
我们从理论和数值上研究了含气泡介质在气泡以高马赫数自由振荡时的声衰减。本文通过将先前的理论扩展到更高的马赫数，扩展了与气泡相关的声学阻尼因子的一种主要形式，进一步完善了含气泡介质中非线性声传播的理论。建立了一个包含二阶液体压缩项的非线性声传播模型，将介质中的声速和密度表示为驱动压力的函数，并考虑了高阶液体压缩对声传播的影响。通过与线性模型和仅包含低阶马赫数项的非线性模型进行比较，验证了所提模型的正确性。当气泡以高马赫数振荡时，与马赫数直接相关的辐射阻尼成为影响声衰减的主要阻尼分量。驱动振幅越高，非线性效应越强，高阶液体压缩效应对声衰减的影响越大，使用所提模型计算声衰减就越有必要。对于高马赫数，分别改变气泡半径和气泡数密度，计算了所提模型与仅包含低阶马赫数项的模型在捕捉与压力相关的衰减方面的差异。由于较小气泡中的辐射阻尼更强，可压缩性的影响变得更加重要。气泡半径越小，与两种模型计算的衰减差异相关的曲线的半品质因数越大，使用所提模型计算与压力相关的衰减就越有必要。这里，半品质因数定义为曲线从最大值下降到其(1/2)倍时对应的频率带宽。在不考虑气泡之间的耦合效应时，曲线的半品质因数不受气泡数密度的影响。
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