压电三迭片式高阶声压梯度水听器研究

Research on High-order Acoustic Pressure Gradient Hydrophone Using Piezoelectric Bimorphs

该文从数学上计算了不同阶声压梯度组合对空间声场的估计误差,分析了差分通道幅度和相位不一致性对有限差分近似误差的影响,研究了水听器自噪声及模数转换量化误差对高阶水听器工作频率下限的制约关系,提出了一种由4片压电三迭片构成的高阶声压梯度水听器,尺寸为Φ100 mm×50 mm,能够测量声场一阶声压梯度和二阶混合声压梯度。利用有限元法计算获得平面波自由声场中水听器各通道的输出电压。计算结果表明,二阶混合声压梯度通道的输出电压响应每倍频程升高12 dB,指向性与纵向四极子声源指向性一致。

The estimation errors on the spatial acoustic field using different order acoustic pressure gradient combinations were analyzed mathematically, and the effect of the inconsistency between the amplitude and phase in the differential channel on the finite difference approximation errors was calculated. The constraints of the self-noise of the hydrophone and the quantization error of analog-to-digital conversion on the lower limit of the operating frequency of the high-order hydrophone were studied. A high-order acoustic pressure gradient hydrophone composed of four piezoelectric bimorphs was proposed. The size of the hydrophone is Φ100 mm×50 mm, capable of measuring the first-order acoustic pressure gradient and the second-order mixed acoustic pressure gradient in the sound field. The output voltage of each channel of the hydrophone in the plane wave sound filed were obtained by finite element simulation. The calculated results show that the output voltage response of the second-order mixed pressure gradient channel increases by 12 dB per octave, and the directivity is consistent with that of the longitudinal quadrupole acoustic source.