| Located in the outposts of national defense,ocean is an important barrier to safeguard national security and an important carrier of China’s "One Belt,One Road" strategy.Acoustic wave is the main carrier of long-distance ocean information transmission.As the core equipment of converting electric energy into acoustic energy,high-power electroacoustic transducer has become one of the most important technologies in Marine military currently.It is the core support for building all-round Marine monitoring and underwater long-distance information transmission,and it is also the most potential important technology and equipment for Marine resource exploration.It has become a strategic commanding point for each country in maritime defense.Ultra-low frequency acoustic wave has the advantage of long propagation distance,and has broad prospects in ocean exploration,development and military fields,so underwater ultra-low frequency transducer has become a hot spot in the field of underwater acoustic detection.Therefore,the research on the key technology of high-power ultra-low frequency giant magnetostrictive transducer will provide important guarantee for national economic development and national ocean governance capacity,and has great strategic significance for China to expand the blue economic space and build the "21st century Maritime Silk Road".This thesis is supported by the National Natural Science Foundation of China National Major Research Instrument Development Project "Multi-frequency and Multi-azimuth Cooperative Acoustic Radar System Oriented to Marine Underwater Moving Target Measurement" [52127901],the National Natural Science Foundation Key Project "Research on High-power and High-efficiency Electro-acoustic Transduction Mechanism and Control Method" [51837005].The research focuses on the magneto-mechanical characteristics test of giant magnetostrictive materials,multi-field modeling method of giant magnetostrictive electroacoustic transducer,equipment development of high-power ultra-low frequency giant magnetostrictive electroacoustic transducer,giant magnetostrictive electroacoustic transducer array and its phase control technology,and solved key technical problems such as giant magnetostrictive electroacoustic transducer multi-field modeling method and equipment development.It provides important support for promoting the technology and equipment of remote underwater target active detection.The research content mainly includes five aspects:(1)Aiming at the problem that the giant magnetostrictive rod did not work in the linear region,resulting in poor acoustic output quality of the transducer,a measuring platform for the magneto-mechanical characteristics of the giant magnetostrictive rod was designed and built,and the magneto-mechanical characteristics of the giant magnetostrictive rod were tested and analyzed under different conditions.The measurement results show that under the bias of 10 mm permanent magnet,the magneto-mechanical characteristics of the giant magnetostrictive rod are the best in the range of 16～28 MPa.Under high power conditions,magnetostrictive rods show strong hysteresis loss characteristics,which cannot be ignored in the modeling process.A material parameter inversion method for giant magnetostrictive rod is proposed.The sensitivity of the material parameters is analyzed and the key parameters affecting the performance of the transducer are established.The impedance characteristics of the electroacoustic transducer were tested,and the key performance parameters of the giant magnetostrictive rod were retrieved by finite element method and optimization algorithm,and the effectiveness of the proposed method was verified from the impedance perspective.The results show that the error is only 4.1%,which indicates the accuracy and applicability of the proposed method,and lays the parameter foundation for the multi-field modeling in the following chapter.(2)Centering on the effective description of the output characteristics of the electroacoustic transducer and the prototype structural optimization,the electroacoustic transducer electromagnetic-machine-acoustic circuit model based on the modularity idea is proposed.The modular model and coupling calculation method of each energy transformation link of the electroacoustic transducer are studied,and the impedance and output characteristics of the electroacoustic transducer are described considering the characteristics of magnetic leakage and material loss.The accuracy of the proposed method is verified by experiments.The experimental results show that the average error of simulation and experimental impedance is 2.6%.Simulation and experiment verify the accuracy of the proposed modeling method.(3)In order to improve the energy conversion efficiency of ultra-low frequency electroacoustic transducer,an optimization method for the development of ultra-low frequency electroacoustic transducer is proposed from the perspectives of electromagnetic structure and mechanical structure,which are the key components of energy conversion.In terms of electromagnetic structure,the giant magnetostrictive rod eddy current barrier technology was studied,the influence of different cutting modes was analyzed,and the improved radial cutting mode was determined,which achieved a significant reduction in eddy current loss,up to 82.6%.At the same time,the optimal design method of excitation coil was studied,and the eddy current loss under different wire structures and sizes was analyzed.In terms of mechanical structure,the influence law of different displacement amplifying structures on machine-acoustic performance was studied,and the IV shell structure was optimized,and then the overall parameters of the shell structure were determined by simulation.Finally,the electrical and acoustic characteristic parameters of the designed transducer are simulated and analyzed.(4)The methods of resisting strong seawater corrosion and high reliable water tightness for the high-power ultra-low frequency giant magnetostrictive transducer are studied.The solutions of electrophoretic anticorrosion and polyurethane potting are proposed.The prototype of the high-power ultra-low frequency giant magnetostrictive transducer was developed.The measurement and calibration of the National Defense Underwater Acoustics Calibration Laboratory of China.The test results show that the developed high-power ultra-low frequency type Ⅳ giant magnetostrictive transducer has a resonance frequency of 106 Hz and a TCR of178.11 d B when the excitation current is 16.6A.The sound source level is 197.2 d B,and the electro-acoustic efficiency is 25.2%.Sound source level index has reached the domestic advanced level.(5)The phase-controlled method and effect of the ultra-low frequency electroacoustic transducer in different array forms are studied.The results show that the phase-controlled technology can realize the high sound source level gain omnidirectional beam scanning.The feasibility of the phase control technique is verified based on the experiment of three-dimensional dense linear array.At the same time,the influence of mutual radiation on the output characteristics of the transducer under the condition of dense array is studied.The results show that the mutual radiation resistance between the arrays is negative under the condition of 1/4wavelength array and positive under the condition of 1/2 wavelength array,which can support the development of high-power electroacoustic transducer array. |
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