次Bjerknes力作用下气泡的体积振动和散射声场

利用Lagrange方程得到了次Bjerknes力作用下气泡的体积振动方程,并探讨了次Bjerknes力作用下不同参数对气泡体积振动振幅和振动初相位的影响,研究了振动初相位差为π和0的气泡对在液体中形成的散射声场特征.结果表明:次Bjerknes作用力下,相邻气泡半径、气泡间距、多方指数均能影响气泡的体积振动振幅,气泡对的均衡半径、气泡间距和驱动频率则对气泡振动初相位产生明显影响;相距很近、相位相差为π的两个气泡的散射声压与气泡体积振动振幅、气泡间距、驱动频率和振动初相位有关,随声场距离成反比减小,与声场位置有关,其平均散射声功率是单个孤立气泡的1/6(kd_(12))~2半径相同、相距很近、相位相同的两个6气泡的散射声压与气泡振动初相位、体积振动振幅、气泡间距、驱动频率有关,随声场距离成反比减小,其平均散射声功率是单个孤立气泡的4倍.

Volume pulsation and scattering of bubbles under the second Bjerknes force

The interaction of bubbles must be taken into consideration in the investigation of sound wave in the liquid containing gas bubbles, particularly in the case where the gas content is high. The force between two air bubbles due to the secondary sound fields radiated by the bubbles is called the secondary Bjerknes force, which makes the dynamics and scattering of bubbles different from a single bubble's. In order to investigate the influence of secondary Bjerknes force on bubbles' pulsation and scattering, we obtain the universal expression of bubbles' pulsation under the secondary Bjerknes force by Lagrange's equation. The influences on volume amplitude and initial phase of different parameter under the second Bjerknes force are discussed, and the scattering of bubbles with phase differences of π and 0 is studied. The results show that the radius of neighbouring bubble, distance between two bubbles, polytropic coefficient and the phase can change the volume amplitude of pulsation under the secondary Bjerknes force. The mean radius of bubbles, distance and the frequency of sound have a significant effect on initial phase; the scattering of two bubbles of small distance and phase difference of π is directional and decreases with distance r, which is related to the volume amplitude, initial phase and distance between two bubbles. The mean scattering power of bubble pairs of phase difference π is 1/6(kd₁₂)² of single bubble's. The scattering of two bubbles with small distance and same phase also decreases with the distance r and relates to the volume amplitude, initial phase and distance between two bubbles. The mean scattering power of bubble pairs of same phase is 4 times as bigger as the mean scattering power of single bubble. It is expected that the mean radiuses, driving frequency and distance between bubbles can be used to change the scattering of bubbles.