本文通过耦合求解非线性声波方程以及多气泡动力学方程，得到了空化云中的声场分布以及气泡径向振动随时间的变化规律，进而研究了空化云中声波频谱在低频段出现带隙的现象、液体中空化云的产热特征，以及生物组织中超声造影剂微泡的增热效应。 我们从数值计算、实验以及理论三个方面讨论了空化云中声波频谱在低频段出现带隙的现象。在数值模拟上，我们发现当空化泡的半径和数密度满足一定条件时，低频段的声信号会被局域在空化云中而无法传出空化云，即空化云底部的声信号频谱在低频段出现了带隙。实验中我们通过使用不同含气量的液体，得到了与数值计算相符的实验结果，并通过实验讨论了频谱带隙特征与空化泡大小和数密度的关系。在理论上，我们通过线性近似的方法，得到了空化云中声波传播特性与气泡半径和声波频率之间的关系，揭示了空化云中频谱带隙出现的原因，从而对声波局域化以及禁带造成的频谱带隙进行了解释和区分。关于空化泡在液体中的热效应研究，我们首先通过数值计算，得到了空化云中气泡壁粘滞产热量以及液体对气泡次级辐射声波粘滞吸收的产热量。通过对比分析二者产热量发现，在强超声作用下，气泡壁粘滞产热起主导作用。另外，当空化云中发生声波局域化时，产热最大值不再出现在气泡共振的情况下。在实验上，我们利用热电偶测量了空化云中的升温，与数值计算的温升结果对比发现，二者在弱声条件下温升结果符合得很好。在强声驱动条件下，实验中的升温幅度低于理论值，原因是在强声驱动下，实验中液体的流动造成了空化云中热量的流失。通过改进实验，我们进一步讨论了液流以及空化泡数密度对升温的影响。微泡的热效应在HIFU消融中起到重要的作用。在数值计算上，我们通过耦合包壳微泡的动力学方程以及非线性声波方程，计算了在生物组织中微泡在HIFU焦点处引起的温升。在实验中将SonoVue溶液注入到组织仿体中，采用热应变方法测得了HIFU焦点处温度随时间的变化曲线。计算与实验结果基本相符，且均表明微泡能够带来更高的温升。另外，我们采用三种不同的包壳微泡动力学模型，模拟了微泡半径随时间的变化关系。结果表明在弱声单气泡条件下，三个模型的结果基本一致。然而在多气泡、强声驱动条件下，三个模型的气泡动力学响应有明显差异。

We calculate the sound field pressure and the bubble radius in cavitation cloud by solving the nonlinear sound wave equation together with the bubble dynamic equation. In this paper we study the spectral gap of the acoustic wave in cavitation clouds, the heat production characteristics of cavitation bubbles and how the coated bubbles enhance the heating process in the tissue.We studied the phenomenon of spectral gap of the acoustic wave in cavitation cloud by numerical calculation, experiment and theoretical analysis respectively. The calculation results show that when the radius and the number density of the bubbles meet some certain conditions, there will be a spectral gap in the low frequency range and the acoustic wave of these frequencies cannot penetrate the cavitation cloud. In the experiment, we used liquids of different gas content to verify the calculation results and studied how the bubble radius and number density will influence the formation of the spectral gap. Through a linear analysis of the nonlinear soundwave equation in bubbly liquids, we interpreted the spectral gap and distinguished the forbidden band and the localization phenomenon in the cavitation clouds theoretically. In the study of the heat production of cavitation clouds, we first obtained the heat generated at bubble walls caused by the liquid viscosity and the heat produced by liquid absorption through numerical calculation. We found that when the intensity of the driving ultrasound is high, the heat generation at bubble walls dominants the heating process. In addition, the heating peak of cavitation clouds will deviate from their resonance point when the acoustic localization appears. In the experiment, we used thermocouple to measure the temperature rise in the cavitation cloud, and the experiment results are in good agreement with the calculation results under the condition of weak driving ultrasound. However, when the intensity of the driving ultrasound is high, the temperature rising in the experiment is lower than the calculation results, because the liquid flow in the experiment causes some heat loss. Then we adjusted the experiment condition and studied the influence of liquid flow and the bubble number density on the temperature rising in the cavitation clouds.The thermal effect of microbubbles plays an important role in HIFU ablation. In numerical calculation, we calculated the temperature rise caused by the bubbles at the focus point of HIFU by solving the dynamic equation of coated bubbles together with the nonlinear acoustic wave equation. In the experiment, we injected the SonoVue solution to the tissue phantom and used the thermal strain method to measure the temperature rise at the focus point of HIFU. The results showed that the bubbles can lead to enhanced heating and the temperature rising in experiments are consistent with the calculation results. In addition, we used the theoretical method proposed in this paper to calculate the variation of the bubble radius with time for three different coated-bubble dynamic models. The results showed that when the driving ultrasound is weak, the dynamic responses of a single bubble obtained by the three models are basically the same. However, under the condition of high intensity driving ultrasound and multiple bubbles, the bubble dynamic responses under the three models are different.