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本文在气泡群振动模型的基础上, 考虑气泡间耦合振动的影响, 得到了均匀柱状泡群内振动气泡的动力学方程, 以此为基础分析了低频超声空化场中柱形气泡聚集区内气泡的非线性声响应特征. 气泡间的耦合振动增加了系统对每个气泡的约束, 降低了气泡的自然频率, 增强了气泡的非线性声响应. 随着气泡数密度的增加, 气泡的自然共振频率降低, 受迫振动气泡受到的抑制增强. 数值分析结果表明: 1)驱动声波频率越低, 气泡的初始半径越小, 气泡数密度变化对气泡最大半径变化幅度的影响越大; 2)气泡振动幅值响应存在不稳定区, 不稳定区域分布与气泡初始半径、驱动声波压力幅值、驱动声波频率等因素有关. 在低频超声波作用下, 对初始半径处在1-10 m之间的空化气泡而言, 气泡初始半径越小, 气泡最大半径不稳定区分布范围越大, 表明小气泡具有更强的非线性特征. 因此, 气泡初始半径越小, 声环境变化对空化泡声响应稳定性影响越显著.An ultrasonic horn can radiate a strong ultrasonic wave into viscous liquid contained in a tank or cylindrical cup, and bubble clusters could be generated by the high-intensity ultrasound in the liquid. In the bubble clusters, interaction of bubbles exists because of the secondary radiation of bubbles. Therefore, the oscillations of bubbles are coupled. On the other hand, the surrounding liquid pressure of the bubbles in the cluster is influenced by the oscillations of the bubbles, which induces a pressure gradient on the boundary of the cluster. Therefore, the oscillation of a bubble inside a cluster is contracted by the formation of the cluster and its structure evolution. In this paper, a cylindrical cavitation bubble cluster is considered as a mixture drop of bubbles and liquids, and the motion of the cluster boundary is proposed with a second two-dimensional (2D) Rayleigh equation related to the difference between the inner mixture pressure and the outside liquid pressure on the boundary. Based on the bubble cluster boundary dynamical equation, a new mathematical model is developed to describe the motion of cavitation bubbles inside a cylindrical cluster when the effects of coupled oscillation are included. Comparing the new model equation with the Rayleigh-Plesset equation of single bubble in unbounded liquid, it is easy to draw the conclusion that the contraction of oscillating bubbles is strengthened by the coupled oscillation of bubbles and the boundary motion. In the cylindrical cluster, the oscillation of bubbles is suppressed, and the natural frequency of bubbles is reduced. The proposed model is used as a basis for the numerical investigation of the nonlinear acoustic response of bubbles. The suppression of the bubble oscillation is strengthened by increasing the number density of bubbles. Comparing numerical curves of the maximum radius of the oscillating bubble, it is shown that there are local peaks which are related to the resonance response of bubbles. In some unstable parameter regions, the maximum radius of the oscillating bubble varies sensitively with the tiny change of the parameters. The parameter space distribution of the unstable regions is related to the initial bubble radius and driving frequency of ultrasound. According to the numerical results related to the parameters, such as bubble number density, initial radius, driving frequency and pressure amplitude of ultrasound, it is found that the unstable acoustic response could be amplified for bubbles of smaller initial radius driven by a low-frequency ultrasound. For cavitation bubbles of initial radii ranging from 1 m to 10 m in low-frequency ultrasonic field, the unstable regions of parameter spaces related to the evolution of maximum radius become broader with the decrease of bubble initial radius and driving frequency of ultrasound. Therefore, the tiny bubbles inside cylindrical clusters have stronger nonlinear properties and the change of the parameters in the dynamical model equation has greater influence on the tiny bubbles.
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Keywords:
- cavitation field /
- cavitation bubbles /
- coupled oscillation /
- acoustical response
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[2] Bjerknes V F K 1966 Field of Force (New York: Columbia University Press) pp45-47
[3] Wang C H, Lin S Y 2011 Acta Acustica 36 325 (in Chinese) [王成会, 林书玉 2011 声学学报 36 325]
[4] Doinikov A A, Zavtrak S T 1996 J. Acoust. Soc. Am. 99 3849
[5] An Y 2011 Phys. Rev. E 84 066313
[6] Nasibullaeva E S, Akhatov I S 2013 J. Acoust. Soc. Am. 133 3727
[7] Arora M, OhlC D, Lohse D 2007 J. Acoust. Soc. Am. 121 3432
[8] Hansson A, Mrch K A 1980 J. Appl. Phys. 51 4651
[9] Wu Y, Hong S, Zhang J, He Z, Guo W, Wang Q, Li G 2012 Int. J. Refract. Met. Hard Mater. 32 21
[10] Verhaagen B, Rivas D F 2016 Ultrason. Sonochem. 29 619
[11] Moussatov A, Granger C, Dubus B 2003 Ultrason. Sonochem. 10 191
[12] Yasui K, Iida Y, Tuziuti T, Kozuka T, Towata A 2008 Phys. Rev. E 77 016609
[13] Wang C H, Mo R Y, Hu J, Chen S 2015 Acta Phys. Sin. 64 234301 (in Chinese) [王成会, 莫润阳, 胡静, 陈时 2015 物理学报 64 234301]
[14] Brotchie A, Grieser F, Ashokkumar M 2009 Phys. Rev. Lett. 102 084302
[15] Lee J, Ashokkumar M, Kentish S, Grieser F 2005 J. Am. Chem. Soc. 127 166810
[16] Wang C H, Hu J, Cao H, Lin S Y, An S 2015 Sci. Sin.-Phys. Mech. Astron. 45 064301 (in Chinese) [王成会, 胡静, 曹辉, 林书玉, 安帅 2015 中国科学: 物理学 力学 天文学 45 064301]
[17] Tu J, Swalwell J E, Giraud D, Cui W, Chen W, Matula T 2011 IEEE Trans. Ultrason. Ferroelectr. Freq. Control. 58 955
[18] Icaza-Herrera M, Fernandes F, Loske 2015 Ultrasonics 58 53
[19] Wang C H, Lin S Y 2010 Acta Mech. Sin. 42 1050 (in Chinese) [王成会, 林书玉 2010 力学学报 42 1050]
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[1] Ying C F 2007 Sci. Sin.-Phys. Mech. Astron. 37 129 (in Chinese) [应崇福2007 中国科学: 物理学 力学 天文学 37 129]
[2] Bjerknes V F K 1966 Field of Force (New York: Columbia University Press) pp45-47
[3] Wang C H, Lin S Y 2011 Acta Acustica 36 325 (in Chinese) [王成会, 林书玉 2011 声学学报 36 325]
[4] Doinikov A A, Zavtrak S T 1996 J. Acoust. Soc. Am. 99 3849
[5] An Y 2011 Phys. Rev. E 84 066313
[6] Nasibullaeva E S, Akhatov I S 2013 J. Acoust. Soc. Am. 133 3727
[7] Arora M, OhlC D, Lohse D 2007 J. Acoust. Soc. Am. 121 3432
[8] Hansson A, Mrch K A 1980 J. Appl. Phys. 51 4651
[9] Wu Y, Hong S, Zhang J, He Z, Guo W, Wang Q, Li G 2012 Int. J. Refract. Met. Hard Mater. 32 21
[10] Verhaagen B, Rivas D F 2016 Ultrason. Sonochem. 29 619
[11] Moussatov A, Granger C, Dubus B 2003 Ultrason. Sonochem. 10 191
[12] Yasui K, Iida Y, Tuziuti T, Kozuka T, Towata A 2008 Phys. Rev. E 77 016609
[13] Wang C H, Mo R Y, Hu J, Chen S 2015 Acta Phys. Sin. 64 234301 (in Chinese) [王成会, 莫润阳, 胡静, 陈时 2015 物理学报 64 234301]
[14] Brotchie A, Grieser F, Ashokkumar M 2009 Phys. Rev. Lett. 102 084302
[15] Lee J, Ashokkumar M, Kentish S, Grieser F 2005 J. Am. Chem. Soc. 127 166810
[16] Wang C H, Hu J, Cao H, Lin S Y, An S 2015 Sci. Sin.-Phys. Mech. Astron. 45 064301 (in Chinese) [王成会, 胡静, 曹辉, 林书玉, 安帅 2015 中国科学: 物理学 力学 天文学 45 064301]
[17] Tu J, Swalwell J E, Giraud D, Cui W, Chen W, Matula T 2011 IEEE Trans. Ultrason. Ferroelectr. Freq. Control. 58 955
[18] Icaza-Herrera M, Fernandes F, Loske 2015 Ultrasonics 58 53
[19] Wang C H, Lin S Y 2010 Acta Mech. Sin. 42 1050 (in Chinese) [王成会, 林书玉 2010 力学学报 42 1050]
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