Effect of geometry change on solid C shaped armature

Abstract

Armature takes an important role in the electromagnetic launch process. High current densities in the armature can result in high local temperature and consequent loss of strength and even melting and erosion. Conventional C-shaped armature is widely used which experiences high current densities in three areas: the leading edge, the trailing edge, and the throat. It is argued that if the armature shape is modified to better align with the magnetic field, the current density distribution could be more uniform. This paper tries to analyze the effect of the geometry change on C-shaped armature at low velocity. The geometry of the armature was changed to improve the current density and temperature distribution and reduce the erosion. Four variants of C-shaped armatures were designed to study the specific features, including a conventional C-shaped armature (CCA), a rounded leading edge C-shaped armature (LCA), a rounded trailing edge C-shaped armature (TCA), and a rounded incorporate edge C-shaped armature (ICA). A novel low-speed experiment was constructed and tested. The armatures were eroded and recovered to compare the improved effect. Then finite element simulations according to the experiments were taken to analyze the further results. It is proved that the curved edge of the armature could reduce the nonuniformity of current density and temperature distribution greatly. LCA and ICA showed less erosion on the contact surface due to the rounded leading edge. The trailing edge could improve the uniform of the current on the interface. ICA is the best choice of the four armatures which combines the effect of LCA and TCA. Erosion and transition mechanism were analyzed at last. A detailed description of the experiments and simulations will be presented in this paper.