Ultrasonic Cavitation And Multi-bubble And Its Radiated Sound Field Study

Compared with the propagation of sound wave in solid or gas, the propagation of sound wave in liquid has its characteristic, which is cavitation when the high-intensity ultrasonic propagates in it. Many applications of ultrasonic are based on the cavitation in liquid. So the researches of theory and experiment of cavitation become focus. The cavitation correlates with many factors, and going with complicated nonlinearity, which makes many difficulties in the researches of the theory of cavitation, so the researches of cavitation are mostly experiment and applications. The applications of cavitation include ultrasonic cleaning,ultrasonic disposal,sonochemical reacting,environment protecting,ultrasonic medicine and therapy, etc. Recently ultrasonic safe dose of ultrasonic therapy becomes the hotspot, which needs urgently many more researches of theory and experiment of cavitation. In future there will be a new revolution in nuclear reaction, for in 2002, Taleyarkhan and his colleagues of the state-run lab of America Oak Ridge alleged that they had found nuclear fusion reaction in ultrasonic cavitation field, which offers a new mode.In this paper following work has been done based on the theory and experiment researches of cavitation:(1) Established the moving equation of two bubbles walls under a sound field and reached the resonant frequency, vibration radius and radiation pressure of the double-bubbles cavitation. By the frequency equation, radius of vibration and sound pressure equation we can see that the movement of two bubbles is different from a single bubble. Resonance frequency, resonance amplitude and radiation pressure are related to the distance between the two bubbles. Making the numerical solution by MATLAB, we found that the resonance frequency and amplitude resonance are increased with the distance of the two bubbles.(2) Studied the cavitation bubbles collapse near the rigid wall in the process of the sound field is and the radiation of sound pressure distribution of a single bubble and double bubbles near the rigid wall is got. Study shows that for the impact of rigid wall the acoustic radiation of cavitation bubble emerges some directional. The distribution of radiation pressure by two bubbles is related with the vacuole collapse time, the distance between vacuoles, and the initial radius of cavitation bubbles. Considering the superposition phase of sound pressure, the test position of the radiation pressure depends on the vacuole's sound pressure amplitude p, sound path difference of the vacuoles to the observation point△1=l1/2 sinθ1,△2=l2/2 sinθ2.This calculation process and result provides the basis for the cavitation calculation near the rigid wall, and provides a theoretical basis for multi-bubble cavitation sound field of radiation to help to amend the motion equation of cavitation bubbles.(3) Studied the cavitation bubbles collapse near the soft wall in the process of the sound field is and the radiation of sound pressure distribution of a single bubble and double bubbles near the soft wall is got. Study shows that for the impact of soft wall the acoustic radiation of cavitation bubble emerges some directional. The distribution of radiation pressure by two bubbles is related with the vacuole collapse time, the distance between vacuoles, and the initial radius of cavitation bubbles.The test position of the radiation pressure depends on the vacuole's sound pressure amplitude p.The results may be useful to the study of bubble clouds.