声场中气泡界面稳定性研究

声致空化广泛应用于表面清洁、生物成像和材料合成等领域，气泡的界面稳定性对空化作用效果有重要影响.考虑液体黏性和表面张力的影响，采用扰动法获得气泡径向运动控制方程的解析解，建立单/双频激振声场中气泡界面稳定性预测模型并求解，获得气泡振荡的临界半径.当气泡初始平衡半径小于临界半径时，气泡界面保持稳定；大于临界半径时，气泡界面失稳.在单频激振声场中，低频激振下气泡界面失稳的低阶临界半径在其共振半径附近，高阶临界半径不受频率影响，与同阶的高频激振下临界半径相当，给出了不同激振幅值下高低频的临界频率值.在双频激振声场中，分3种情况（即双低频激振、高频+低频激振和双高频激振）讨论声场中关键参数（即激振频率、振幅分配比和总的声压幅值）对气泡界面失稳临界半径的影响.

Investigation of the interface stability of gas bubbles in the acoustic field

Acoustic cavitation is widely used in many fields, such as surface cleaning, biological imaging, and material synthesis. Interface stability of gas bubble plays an important role for the effects of cavitation. In this paper, considering the influence of liquid viscosity and surface tension, the perturbation method is used to obtain the analytical solution of the governing equation for the radial oscillation of the bubble. A model of interface stability of gas bubble in the acoustic field with single/dual-frequency excitations is established and solved, and the critical radius of the bubble oscillation is obtained. When the radius of the bubble in the initial equilibrium is less than the critical radius, the interface of the gas bubble remains stable. Otherwise, the interface of the gas bubble becomes unstable. In a single-frequency-excited acoustic field, under low frequency excitation, the low-order critical radii of the bubble are near its resonance radius; the high-order critical radius of the bubble, not influenced by frequency change, is equivalent to the same high-order critical radius of the bubble under high-frequency excitation. The critical frequency values of high and low frequencies under different excitation amplitudes are obtained. In an acoustic field under dual frequency excitation, the influences of key parameters (i.e. the ratio of the frequencies, different ratios of pressure amplitudes and total acoustic pressure amplitude) on the critical radius of bubble interface instability are discussed in three cases (i.e. double low frequencies excitation, high frequency + low frequency excitation and double high frequencies excitation).