水声换能器液腔振动理论研究

Helmholtz transducer is a kind of low-frequency, high-power, deep-water sound source, widely used in the low-frequency active sonar and marine resources exploration equipment. This subject introduces multi-fluid cavity structure into Helmholtz transducer for expanding operating bandwidth of the transducer. It is called multi-fluid cavity Janus-Helmholtz transducer. By researching the phase relationships of sound pressure generated by inner fluid-cavity and outer fluid-cavity of the transducer and longitudinal vibration of the Janus transducer, the mechanism of expanding operation bandwidth by using outer fluid cavity can be explicated;Using lumped parameter model of the elastic chamber to solve additional impedance which introduced into the cavity by elasticity of the chamber, the general expression of fluid cavity resonance frequency can be deduced and the equivalent circuit diagram of the transducer can be drawn, and impedance characteristics, transmitting voltage response and source level of the transducer can be solved. All of the work can provide theoretical basis for the design of broadband multi-fluid cavity Janus-Helmholtz transducer.Researching the variation of the impedance characteristics of the transducer in high hydrostatic pressure environment, and it can provide technical support for forecasting the real performance of the transducer.

Helmholtz换能器是一种低频、大功率、深水声源，广泛应用于低频主动声呐以及海洋资源勘探设备中。本课题拟将多液腔结构引入到Helmholtz换能器中，以拓展换能器的工作带宽，称之为多液腔Janus-Helmholtz换能器。拟通过对多液腔Janus-Helmholtz换能器内液腔、外液腔及Janus换能器纵向振动产生的声压间相位关系研究，确定换能器实现宽带发射的机理；利用弹性腔体的集中参数模型求解弹性腔体引入到液腔中的附加阻抗，推导内、外液腔谐振频率一般表达式，绘制多液腔Janus-Helmholtz换能器等效电路图，求解换能器的阻抗特性、发送电压响应、声源级等电声性能，为设计宽带多液腔Janus-Helmholtz换能器提供理论基础；拟研究高静水压力环境下换能器的阻抗特性变化规律，为预报换能器深水工作时的真实性能提供技术支持。

为提高我海军探测安静型潜艇的能力，增强对深海油气资源勘探的技术水平，开展了基于Helmholtz共振腔的低频大功率宽带水声换能器方面的理论研究。主要研究了利用多液腔谐振拓展Helmholtz换能器工作带宽的机理、腔体的弹性壁对换能器声学性能的影响规律、液腔振动对结构振动的影响规律，换能器的制作工艺以及不同水声环境下的工作特性。研究结果表明，利用多液腔可以有效地拓展Helmholtz换能器的工作带宽；在低频段，腔体的弹性对液腔谐振频率有明显的影响——腔体的順性越大，液腔的谐振频率越低；腔体的材质、结构尺寸对发送电压响应及电导纳影响明显，尤其是对Janus换能器的纵振动影响强烈。依据研究结果，设计只做了一只多液腔Janus-Helmholtz换能器样机，测试结果显示工作带宽500-2500Hz，最大声源级202dB，打压试验显示换能器可承受1000米静水压力。该研究为利用Helmholtz共振腔设计低频、宽带、小尺寸、深水换能器提供了理论支撑，研制的试验样机可应用于低频主动声纳、深海油气资源地震勘探设备中，具有较高的军事和社会价值。