MEMS仿生矢量水听器“桔瓣”式复合效应封装技术研究

The MEMS hydrophone is one of the research hotspot in the acoustic transducer field in domestic and international world at present. The MEMS bionic vector hydrophone invented by the North University of China has got certain recognition in the domestic and international field for its small size, vector property, low-cost, rigid mount and other advantages. While the vector hydrophone's low sensitivity ， narrow frequency response range and poor ability of suppressing flow noise, it still has some way to achieve its engineering application.To this end, a kind of "orange petal"-type package structure for MEMS bionic vector hydrophone based on the fluid continuity equation is proposed in the project, and by studying the compound effect of this package structure to increase the sensitivity and the ability of anti-flow noise, broaden the bandwidth response of the vector hydrophone. First, a Acoustic model and fluid model of the "orange petal"-style package structure is established to analyze the sensitivity; and structure model, finite element model is also established to analyze the bandwidth response. Second, In order to verify the ability of anti-flow noise, the MEMS vector hydrophone with "orange petal"package will be tested in the typical application environment. Finally, The reliability will be verified through the vibration test, impact test, temperature cycling test and other tests. Ultimately realizing the expected goal that the "orange petal"-type package structure increases 20dB than the current package structure in sensitivity, increases more than 20dB in the ability of suppressing the flow, improves greatly in reliability, and lay good foundation for MEMS vector hydrophone engineer application.

MEMS水听器是当前国内外声换能器领域研究的热点之一。由中北大学研制的MEMS仿生矢量水听器因其具有体积小、矢量性、成本低、刚性安装等优势，在国内外得到一定的认可，但离工程应用还有一定距离，主要表现在灵敏度偏低，频响带宽较窄，抗流噪声性能差等几个方面。为此，本项目基于流体连续性方程提出MEMS仿生矢量水听器"桔瓣"式封装结构，通过研究该封装结构的复合效应机理，以此提高水听器的灵敏度、频响范围和流激噪声抑制能力。首先，针对该"桔瓣式"封装进行声学建模、流体建模分析其灵敏度；结构建模、有限元仿真分析其频响带宽。其次，通过典型水域环境实验比对验证该封装结构的流激噪声抑制能力。最后，通过振动试验、冲击试验、温循试验等验证其可靠性。最终实现灵敏度提高20dB，带宽拓展1～2倍，流噪声抑制能力提高20dB以上，可靠性有较大提高，为MEMS仿生矢量水听器的工程应用奠定基础。

本项目主要针对当前MEMS仿生矢量水听器流噪声灵敏度低、频响范围窄、流噪声抑制能力差的难题，基于声波连续性方程设计了一种新型“桔瓣”式封装结构，并在“桔瓣”式封装结构的基础上设计一微型导流罩。对该“桔瓣”式封装进行声学和结构建模仿真分析，结果表明该“桔瓣”式结构具有声波汇聚作用，在“桔瓣”中心处声信号增大了10倍，加入“桔瓣”支撑体的封装结构的固有频率相比单一透声帽结构的固有频率提高了2倍。并针对微型导流罩建立数学模型，计算不同流速，不同结构尺寸下，TBL压力起伏的大小；研究弹性封装壳体的传递函数随材料属性（如弹性模量，密度等）的变化机制；研究该微型导流罩对水听器灵敏度的耦合影响，确实导流罩的结构尺寸和材料。最后，基于矢量水听器校准装置测试，结果表明“桔瓣”式封装结构MEMS仿生矢量水听器实现灵敏度提高20dB，带宽拓展至2000Hz，拓展2倍。进行典型湍流水域试验，与前期封装结构对比，MEMS矢量水听器抑制流噪声的能力可以提高20dB左右。千岛湖湖试进一步验证MEMS矢量水听器的水声探测性能以及环境适应性能, 且“桔瓣”式MEMS矢量水听器在自由场表现出了良好的“8”字型余弦指向性及对称性。该项目达到了项目申请预定目标，并为该水听器的工程应用奠定坚实的理论和技术基础。