气体火花开关高温气体冷却的三维模拟

3-D Simulation of High Temperature Gas Decay of Gas Spark Gap

高温气体的冷却是影响气体火花开关重复运行的主要因素。为解决高温气体冷却研究采用一维或二维模型且不考虑气体导热系数、定压比热、粘性系数随温度变化的影响引起的计算不精确,三维数值模拟及理论分析了气体开关导通后开关通道内的高温气体冷却。结果表明,气体导热系数越大、定压比热越小、粘性系数越小、气体冷却速度越快;用得出的上述参数随温度变化的拟合公式对氮气、氢气气体开关中高温气体冷却三维模拟证明了氢气的冷却速度明显好于氮气。

To improve the repetition rate of the spark gap, the high temperature gas decay is studied. A 3-D model is established for simulation of temperature decay of gas with high temperature. According to continuity equation, momentum equation, energy conservation equation, ideal gas state equation and using finite element analysis method, the simulation resuJts and theory analysis show that gas with higher heat transfer coefficient, smaller specific capacity at constant pressure and smaller dynamic viscosity has the faster temperature decay velocity. The adaptive equations of heat transfer coefficient, specific capacity, dynamic viscosity varied with temperature were given; Using these equations, simulation of high temperature gas decay after the spark gap is closed for nitrogen and hydrogen is done, and the results show that the velocity of temperature decay of hydrogen is faster than nitrogen＇s. For hydrogen, the peak temperature of high temperature gas can be cooled to 1 000 K in about 7 ms, while it needs about 27 ms for nitrogen to be cooled to the same temperature. Therefore, hydrogen is a better gas dielectric for repetitive gas spark gap.