水中脉冲放电等离子体声源建模方法及能量输运特性研究

Intense acoustic pulse generated by underwater plasma acoustic source based on pulsed discharge is important and valuable to be applied in the key civilian and military fields of deep earthquake prospecting, long-distance target detection, underwater security defense and so on. For the current state of low electro-acoustic transition efficiency and indistinct energy transport mechanism, the research on the modeling method and energy transport characteristics for underwater plasma acoustic source based on pulsed discharge is developed in this project. First, the characteristic parameters for underwater plasma based on pulsed discharge are investigated experimentally. With the energy conversion relation and internal energy balance analyzed for different discharge periods, the key factors influencing the electro-acoustic conversion efficiency are achieved. Second, the microscopic species composition of plasma is analyzed according to the characteristic parameters and meanwhile, the thermodynamic properties and transport coefficients of the plasma including metal vapour are calculated. Then, the numerical model for underwater plasma based on pulsed discharge is established with the consideration of electrode erosion and radiation effect in order to quantitatively analyze the transport processes for internal mass flow and energy flow of the plasma. Finally, based on the simulation and experiment results, the influences of different factors on energy conversion relation and energy transport characteristic are investigated from both microscopic and macroscopic aspects and then, the method to enhance the electro-acoustic conversion efficiency for the plasma acoustic source forms, which provides significant basis for the development of high-power underwater plasma acoustic source in the future.

水中脉冲放电等离子体形成的强声脉冲在深层地震勘探、远距离目标探测以及水下安防等关键民用和军事领域具有重要的应用价值。针对水下等离子体声源电声转换效率较低以及能量输运机理尚不清晰的现状，本项目拟开展水中脉冲放电等离子体声源建模方法及能量输运特性研究。首先，实验研究不同条件下水中脉冲放电等离子体的特征参量，分析不同放电阶段的能量转换关系及内部能量平衡，获得影响电声转换效率的关键因素。其次，根据特征参量分析等离子体微观粒子组分，计算包含金属蒸汽的等离子体热力学参数和输运参数。在此基础上，建立考虑电极烧蚀以及辐射效应的水中脉冲放电等离子体数学模型，定量分析等离子体内部质量流和能量流输运过程。最后，综合仿真和实验结果，从宏观和微观两个角度研究不同因素对能量转换关系以及能量输运特性的影响规律，形成提升等离子体声源电声转换效率的方法，为未来大功率水下等离子体声源的研制提供重要依据。

本项目围绕水中脉冲放电机理及其关键影响因素开展研究。首先，搭建了水中脉冲放电实验测试平台，研究了水中脉冲放电的电声特性及其关键影响因素，获得了水中电击穿现象产生的原因、负载特性的计算分析以及不同的放电电容、电极参数对气泡运动以及声脉冲特性的影响规律。其次，围绕当前变压器内部故障燃弧引起变压器发生爆炸等热点问题，将水中脉冲放电的实验原理和方法拓展到变压器油中故障燃弧领域，开展了油中脉冲放电的实验研究。基于110kV实际变压器腔体，研究了短路大电流内部故障燃弧条件下变压器油中气泡运动特性以及伏安特性，测量并分析了气泡发生、发展以及内部温度的变化规律，为变压器油中故障燃弧的防护设计提供了实验证据和设计依据。最后，基于水中脉冲放电可以快速建立电弧电压这一现象，提出了基于水中脉冲放电的直流开断新原理。搭建了基于水中脉冲放电的直流开断测试平台，完成了电弧电压分断及并联MOV分断的直流分断实验，获得了不同内径、不同电极材料等条件下的水中电弧电压、电流波形和放电过程，揭示了不同因素对开断电压以及内部压力的影响。. 通过本项目的研究，掌握了水中以及油中脉冲放电的气泡脉动特性、伏安特性及其关键影响因素，丰富了现有的液体放电理论，为未来大功率水下等离子体声源的设计开发、变压器内部故障燃弧防护以及液体放电理论在直流开断中的应用提供了新的思路和借鉴。