电磁轨道发射器动态发射过程的数值模拟

Numerical simulation of dynamic launching in electromagnetic rail launcher

针对电磁轨道发射器动态发射过程的数值模拟问题,基于矢量磁位A和时间积分标量电位V,采用节点单元法,并选择运动坐标系描述运动问题,推导出动态发射下的电磁轨道发射器三维涡流场有限元离散方程。结合温度场控制方程,建立电磁轨道发射器的三维电磁-温度耦合有限元模型。针对一个电磁轨道发射器动态发射问题,对模型进行数值模拟,得到了动态发射下轨道及电枢的温度场分布特点及发射器电感梯度随时间的变化规律。计算结果表明,模型计算出的脉冲电流峰值、出口电流大小、出口速度等参数均与试验结果吻合较好,验证了所开发的有限元程序代码的正确性。

For the numerical simulation method of the dynamic launching in electromagnetic rail launcher, a discrete formulation of three dimensional transient eddy problem for electromagnetic rail launcher considering dynamic launching was established, based on the magnetic vector A and the time integrated electrical scalar potential V, combined by using nodal element method and the moving coordinate frame to deal with the motion. The corresponding three dimensional magnetic-thermal coupled model was formed finally by using the governing equation for thermal field. The dynamic launching process of an electromagnetic rail launcher was simulated by the finite element model. Numerical analysis results of FEM （finite element method） code and the experiment results were compared and analyzed. The characteristic of thermal field distribution for launcher and the variation of inductance gradient with time were obtained by the model. Results show that the magnitudes of the pulsed current, muzzle current, and muzzle velocity have good correspondence with measure dates respectively, which has verified the correctness of the FEM code.