导轨式电磁发射装置电枢熔化波有限元计算

Finite Element Analysis of Melt Wave Ablation in Electromagnetic Rail Launcher Armatures

针对单元烧蚀算法精度较低的问题,基于导轨式电磁发射装置的二维控制方程,推导出采用求解量移动法处理运动问题的伽辽金有限元离散方程,建立了电磁-温度-运动耦合场有限元计算模型。以单元节点为烧蚀判断对象,采用节点烧蚀算法处理电枢材料烧蚀问题,建立了电枢熔化波模型,对运动电枢的烧蚀速度进行了数值计算。模型的计算结果表明:在激励电磁感应强度为40T、电枢运动速度为150m/s的情况下,采用节点烧蚀法得到的熔化波烧蚀速度为Barber理论模型计算值的94%,而相关文献采用单元烧蚀法的计算值为Barber理论模型计算值的73%。因此,与采用单元烧蚀法相比,采用节点烧蚀法的计算值与Parks和Barber两个经典理论模型的计算值更加相近,验证了该方法的正确性。

Aiming at the low accuracy of element melt method in predicting the wave melt ablation （WMA） velocity, a new finite element method of melt wave ablation is proposed. Based on a two-dimensional governing equation of electromagnetic rail launcher, a Galerkin form finite element discrete formulation for dealing with moving boundary by potential moving method is derived, then the finite element model of transient electromagnetic-thermal-moving coupling problem in two dimensions is established. Using node element as the criterion, the armature＇ WMA model is built. Computational results show that when the armature moving speed is 150 m/s and the applied magnetic induction intensity is 40 T, the WMA velocity predicted by the node melt method （NMM） is 94% of that predicted by Barber＇s models, while the WMA velocity predicted by Stefani using element melt method（EMM） is 73% of that predicted by Barber＇s models. Thus, compared with EMM, the WMA velocity predicted by NMM is closer to the results of Parks＇ and Barber＇s classic models, which verifies the correctness of the proposed NMM method.