弯曲圆盘驱动的双Helmholtz共振腔换能器

使用双面同相振动的弯曲圆盘换能器驱动双Helmholtz共振腔,既放大了弯曲圆盘换能器弯曲共振频率以下频段的声输出,又利用两个Helmholtz共振腔的同相声源辐射模型实现了在Helmholtz共振频率处的"∞"字形垂直指向性,实现了低频指向性声发射。阐述了换能器实现"∞"字形低频指向性发射的机理,研究了腔体长度、金属圆片厚度及弯曲圆盘边缘简支厚度等关键结构参数对Helmholtz共振频率的影响,求解了换能器的发送电压响应、指向性等参数。依据仿真结果制作了实验样机,在消声水池中进行了电声性能测试。测试结果显示,指向性形状及液腔共振频率与仿真结果基本相符。这种由弯曲圆盘驱动的双Helmholtz共振腔水声换能器为实现水声换能器小尺寸、低频指向性发射提供了一种技术手段。 

Dual-Helmholtz resonator transducer driven by flexural disc

An underwater acoustic transducer with dual-Helmholtz resonator is presented.The acoustic output of flexural disc transducer below its resonant frequency can be amplified by Helmholtz resonators,the "∞" beam pattern can be obtained due to in-phase radiation of two Helmholtz resonators.Thus,the transducer has the characteristic of low frequency directional transmitting which is difficult for low frequency,small size transducers.The principle of achieving directivity for the low frequency transducer is described.Finite element model is modeled by ANSYS software for studying its acoustic performance.The influence of key structural parameters such as the length of cavity,the thickness of metal disc in flexural disc transducer and the thickness of simply supported structure on Helmholtz resonant frequency have been investigated.The transmitting voltage response and directivity are solved.The prototype is fabricated based on simulation dimension result,transmitting voltage response and directivity are tested in anechoic tank.Test results revealed that the transducer has "∞" vertical directivity at Helmholtz resonant frequency,the beam pattern and Helmholtz resonant frequency are in good agreement with simulation results.The transducer presented in this paper can provide technical support for low frequency directional transmitting with small size.