指向性宽带四边形弯张换能器理论研究

Low-frequency and high-power underwater transducers are both needed in ocean monitoring and active detection of submarine as a source, and flextensional transducer is a typical low-frequency and high-power source in underwater acoustic field. Four-sided flextensional transducer has four bending beams, and combinations of convex-concave changes of bending beams determine vibration modes and acoustic radiation modes of flextensional transducer. More research is proceeded to shell structure and driving method of four-sided flextensional transducer, and theoretical model of broadband four-sided flextensional transducer which has directivity is proposed. Theoretical analysis is carried out with equivalent circuit method and acoustic radiation mode analytical method, and simulation model is established utilizing finite element software to calculate vibration modes and electro-acoustic characteristics. Solving theoretical problems of flextensional transducer such as directional transmitting and low-frequency broadband working is emphasis.

海洋监测和潜艇主动探测都需要使用低频大功率水声换能器作为声源。弯张换能器是水声领域典型低频大功率声源。四边型弯张换能器有四条弯曲梁，在同相激励的情况下，弯曲梁的凸凹变化的组合决定了弯张换能器的振动模态及其声辐射模态。对四边型弯张换能器的壳体结构和驱动方式进行深入研究，提出指向性宽带四边型弯张换能器理论模型。利用等效电路法和声辐射模态分析法进行理论分析，利用有限元软件建立换能器的仿真模型，进行振动模态分析和电声特性计算。重点解决弯张换能器的指向性发射和低频宽带工作等理论问题。

海洋监测和潜艇主动探测都需要使用低频大功率水声换能器作为声源。弯张换能器是水声领域低频大功率声源，四边型弯张换能器有四条弯曲梁的弯张换能器。对四边型弯张换能器的壳体结构和驱动方式进行深入研究，提出指向性宽带四边型弯张换能器理论模型。利用有限元软件建立换能器的仿真模型，进行振动模态分析和电声特性计算。针对弯张换能器的低频宽带工作、指向性发射和超低频声发射等热点问题开展研究。提出对称式宽带四边型弯张换能器，进行有限元仿真分析，完成结构优化，根据优化的结果制作换能器，在水池中完成测试，换能器的工作带宽为2-6kHz，最大发送电压响应达到140dB。提出指向性四边型弯张换能器，利用非对称激励和非对称壳体实现1-3kHz低频指向性发射，最大值与最小值之间的差值为13dB。开展超低频四边型弯张换能器研究，利用壳体外面增加辐射结构和稀土激励的方法，降低换能器的工作频率，最终实现工作频率200Hz，声源级达到180.4dB。