涡旋式大功率超声发声器的发声机理研究

The vortex-type (ultrasonic) generator is the simplest fluid dynamic ultrasonic generator which can be used for gas and liquid. Previous studies has used gas as the driving source, only for the cylindrical chamber sounder and focused on experimental analysis but seldom explored the mechanism of phonation. Sound generation of vortex-type generator is a complex physical process of the interaction of multiple physical fields. Based on the theory of fluid acoustics, the relationship between the coupling of the flow-solid-acoustic multi-physics field and the acoustic radiation of the vortex-type sounder is analyzed by numerical calculation and simulation method to optimize the geometrical shape and geometric parameters of the sounder. The influence of fluid properties and flow field parameters on the acoustic radiation and the relationship between shape and geometric parameters and acoustic radiation is studied experimentally. Then based on the theoretical simulation and experimental results, the shape and geometric parameters of the sounder are analyzed and optimized. The research focuses on the study of the mechanism of the vortex-type ultrasonic generator, and explores the physical model of the coupling between the jet and the sounder. It is expected that the acoustic characteristics associated with controll such as frequency, sound radiation intensity, radiation directivity, sound field distribution and so on can be predicted accurately in theory. The results of this study will provide scientific basis for the design and control of high power fluid dynamic ultrasonic generator and its wide application.

涡旋式(超声)发声器是结构最简单，且可气、液两用的一种流体动力型超声发声器。已往研究以气体为驱动源，仅针对圆柱形腔室的发声器，侧重实验分析，甚少探究其发声机理。涡旋式发声器的发声是多物理场相互作用的复杂物理过程。本项目基于流体声学理论，采用数值计算和模拟方法，分析流-固-声多物理场耦合作用与涡旋式发声器声辐射的关系，以优化发声器的几何形状和几何参量；通过实验探寻流体属性及流场参量对发声器声辐射的影响，探究几何形状和几何参量与发声器声辐射的相关关系；结合理论模拟和实验结果，归纳分析和优化发声器的几何形状和几何参量。项目研究工作侧重于涡旋式超声发声器发声机理的研究，探究射流与发声器的耦合发声所涉及到的物理模型，期望从理论上能够较准确地预示和控制有关的声波特征，如频率、声辐射强度、辐射指向性、声场分布等。项目成果将为大功率流体动力型超声发声器的设计与控制及其广泛推广应用提供科学依据。

涡旋式超声发声器是一种气、液两用的流体动力型超声发声器，潜在应用广泛。虽然发现较早，但从发声效率方面考虑，声功率输出与入口气流功率的比值却不是很高，限制了其应用。但相比于其他流体动力型发生器，涡旋式发生器具有结构简单、易加工、性能稳定、寿命长等优势。源于此，本项目从提高涡旋式超声发声器声辐射性能出发，基于流体声学理论，开展了相关研究工作。在对传统漩涡哨研究的基础上，项目组主要开展了如下工作：.基于减少流阻影响的考虑，设计了变截面出口型旋涡哨；借鉴电子学中推完放大器的理念，设计了双入口型哨，并进而设计了多入口型旋涡哨；借鉴膛线管促使炮弹旋转的思想，设计了来复线出口型旋涡哨，进而设计了腔体来复线型旋涡哨等。.针对上述各种新型涡旋式发声器，采用数值计算模拟和实验分析方法，探究了哨的结构、形状、几何尺寸以及流体参量与与发声器声辐射的相关关系；归纳分析和优化发声器的几何形状和几何参量。.研究分析表明，与传统旋涡哨相比，上述新型涡旋式发声器的声辐射性能都有不同程度的显著提升。其中来复线型各类涡旋式发声器尤为突出。.鉴于涡旋式发声器相比于其它类型超声发声器的固有优点，上述研究成果对于高效、高频涡旋式发生器的设计具有积极的科学指导意义，对于拓展和推进大功率超声技术（如超声加工、超声清洗、声化学、超声降解、超声解堵、超声除尘等）在国民经济建设中的应用具有重要的实际应用价值。