大功率超低频膜结构电磁声源振动特性研究

A Study on Vibration Characteristics of High-power Ultra-low Frequency Membrane-type Electromagnetic Acoustic Sources

摘要:

膜结构电磁式声源具有体积位移大、超低频声场可控、适装性佳等显著优势，在扫雷声源方面具有广阔的应用前景。辐射膜是声源核心振动部件，研究辐射膜的振动特性对于电磁声源的设计及应用具有重要意义。研究了一种膜结构电磁声源振动特性的解析方法。首先，建立真空中电磁声源圆环膜自由振动的解析模型。其次，采用分离变量法求解得到真空中圆环膜自由振动的固有频率和振型，通过与文献数据对比及有限元仿真验证了理论解的正确性。然后，分析了不同边界条件下和圆环膜半径的变化对膜在真空中的振动特性的影响。最后，考虑声源实际水下工况粘性液体负载与内部填充压力的影响，得到了电磁声源实际工况中不同尺寸圆环膜低频强迫振动的幅频特性与声源振动体积位移。所提方法可较准确地反映实际工况下电磁声源振动特性与声辐射能力，可为大功率电磁声源的设计和结构优化提供重要参考。

关键词:圆环膜;电磁声源;分离变量;频率特性

Abstract:

Membrane-type electromagnetic acoustic sources have the advantages of large volume displacement，controllable ultra-low frequency acoustic field and good adaptability，so they have broad application prospect in the field of minesweeping acoustic source. Radiation membrane is the core vibration component of an acoustic source. It is of great significance to study the vibration characteristics of radiation membrane for the design and application of electromagnetic acoustic sources. In this paper，an analytical method for the vibration characteristics of an electromagnetic acoustic source with membrane structure is studied. Firstly，the analytical model of the free vibration of the circular membrane of the electromagnetic acoustic source in vacuum is established. Secondly，the natural frequencies and modes of free vibration of the circular membrane in vacuum are obtained using the method of separation of variables. The correctness of theoretical solution is verified by comparing the calculated natural frequencies with the data in the references as well as finite element simulation. Then，the influence of different boundary conditions and the change of the radius of the circular membrane on the vibration characteristics of the membrane in vacuum is analyzed. Finally，considering the influence of viscous liquid loads and internal filling pressure，the amplitude-frequency characteristics and volume-displacement of the low frequency forced vibration of the circular membrane with different sizes in actual working conditions of the electromagnetic acoustic source are obtained. The method presented in this paper can accurately reflect the vibration characteristics and acoustic radiation capacity of the electromagnetic acoustic source under actual working conditions，and can provide an important reference for the design and structural optimization of high-power electromagnetic acoustic source.

Key words:circular membrane; electromagnetic acoustic source; separation of variables; frequency characteristic