聚焦超声振动球壳的声压数值仿真及测量研究

Numerical simulation and measurement of acoustic pressure of focused ultrasonic vibration spherical shell

为了解决高强度聚焦超声的声压场测量复杂、能量损失等问题,设计出了新型聚焦超声振动球壳装置,采用精确、便捷的测量方法,研究了聚焦超声振动球壳装置的声压场分布规律。建立了开口直径60 mm的聚焦超声振动球壳声压计算模型,计算了聚焦超声焦平面内垂直于声压轴方向上的声压理论值,分析了不同聚焦超声球壳孔径对声压轴处声压分布的影响;同时利用COMSOL软件对聚焦超声球壳的声压级进行了数值模拟,搭建了探针式水听器测量系统,通过实验验证了聚焦超声振动球壳的声压场分布。研究结果表明:随着聚焦超声振动球壳开口半径的增加,焦点附近主瓣的声压增加,其焦斑变小,声压在焦点处增大,声能量比较集中,聚焦超声振动球壳系统具有显著的聚焦特性;聚焦超声振动球壳比以往的高强度聚焦超声的声焦距更符合几何焦距,且误差较小,数值仿真结果与实验测量基本一致。

In order to solve the problems of complex measurement of sound pressure field and energy loss in high intensity focused ultrasound a new type of focused ultrasonic vibration spherical shell was designed. The distribution of sound pressure field in focused ultrasound vibration spheri cal shell by precise and convenient measurement method was studied. The model for calculating the sound pressure field of focused ultrasonic vibra tion spherical shell with opening diameter of 60 mm was established. The sound pressure perpendicular to the axis in the focal plane of focused ul trasound was calculated theoretically. The influence of the different aperture of focused ultrasound spherical shell on the distribution of the sound pressure at the axis of sound pressure was analyzed. At the same time the sound pressure level of focused ultrasonic spherical shell was simulated by COMSOL. Secondly probe hydrophone measurement system was built to verify the distribution of sound pressure field of focused ultrasonic vi bration spherical shell. The results show that the acoustic pressure of the main flap near the focal point increases with the increase of the opening radius of the focused ultrasonic vibrating spherical shell. When the opening radius increases the focal spot become smaller the sound pressure in creases at the focal point and the acoustic energy is more concentrated. The focused ultrasonic vibration spherical shell system has remarkable fo cusing characteristics. The acoustic focal length of focused ultrasound vibration spherical shell is more in line with the geometric focal length and the error is smaller than that of high intensity focused ultrasound. Numerical simulation is basically consistent with experimental measurement.