水下单一振子涡旋声束的产生及其轨道角动量传递机理的研究

Acoustic vortex,characterized by s screw phase dislocation of the wave field around its propagation axis with a magnitude null at its core. Because its special spatial distribution, acoustical vortex has potential applications in the fields of particle manipulation and underwater acoustic communication. In this project, the generation method of the acoustic vortex with single vibrator and the transfer mechanism of the orbital angular momentum of the acoustic vortex will be studied. Firstly, the theory model, which is used to compute the orbit angular momentum between an acoustical vortex and the particle, is setup based on the theory of the acoustic radiation torque and the relationship between the acoustic parameters and the transfer efficiency of the orbital angular momentum of the vortex beam are obtained theoretically.Secondly, based on the properties of the acoustical vortex, an acoustic vortex generator is designed to produce a stable acoustic vortex beam using the sandwich piezoelectric transducer connected with a phase modulation sheet. The effect of the structure parameters of the transducer on sound field distribution are analyzed numerically using finite element method. Thirdly, the influences of the acoustic parameters of the fluid medium and the elastic and the sound absorption of the particle on the transfer of the orbital angular momentum are calculated based on the theory and the numerical simulation results. Finally, the orbital angular momentum are measured at different conditions for different vortex beam to obtain the optimal structure of the experimental system for the rotation manipulation of the particles. The study will provide a basement for the applications of the acoustical vortex in the acoustical particle manipulation and underwater acoustic communication.

声涡旋是指声波在传播过程中由于相位的奇异性而发生螺旋状扭转，出现中心位置声强为零的现象。由于其特殊的空间分布，声涡旋在粒子操控、水下声通信等领域具有潜在的应用。本项目拟对单一结构涡旋声束换能器和涡旋声束与粒子间轨道角动量传递的机理进行研究。第一，依据声场与粒子相互作用的声辐射力矩理论，建立轨道角动量传递的理论模型，获得涡旋声场参数与轨道角动量传递效率之间的定量关系；第二，结合涡旋声束的特点，采用大功率压电换能器前端加相位调制板的方法，设计具有稳定输出的涡旋声场发生器，并应用有限元仿真，分析换能器的结构参数对声场分布的影响；第三，以理论计算和有限元仿真为基础，分析涡旋声场中液体介质的声参数、粒子的弹性和声吸收等因素对轨道角动量传递的影响;最后，通过实验测量在不同条件下声场的轨道角动量，获得用涡旋声束操控粒子旋转系统的最优工作参数，为声涡旋技术在粒子操控和声信息传递方面的应用奠定基础。

声涡旋是指声波在传播过程中由于相位的奇异性而发生螺旋状扭转，出现中心位置声强为零的现象。由于其特殊的空间分布，声涡旋在粒子操控、水下声通信等领域具有潜在的应用。本项目对单一结构涡旋声束换能器和涡旋声束与粒子间轨道角动量传递的机理进行了研究。第一，依据声场与粒子相互作用的声辐射力矩理论，建立了涡旋声束粒子声散射和粒子操控的理论模型，获得涡旋声场参数与声场分布、粒子在声场中受到的辐射力之间的关系；第二，结合涡旋声束的特点，采用大功率压电换能器加相位调制的方法，设计出具有稳定输出的涡旋声束发生器，并应用有限元仿真，分析了换能器的结构参数对声场分布的影响；第三，利用理论计算和有限元仿真，分析涡旋声场中液体介质的声参数、粒子的弹性和声吸收等因素对粒子声操控的影响;最后，通过实验实现了用涡旋声束操控粒子旋转的研究目标。研究结果为声涡旋技术在粒子操控和声信息传递方面的应用奠定了基础。