Simulations on Saddle Armature With Concave Arc Surface in Small Caliber Railgun

Keeping good electrical contact between armature and rails is an important issue in the electromagnetic launch process. At the start of railgun launching with driving current ramp-up, the appearance of aluminum coating tends to be concentrated on the outsides of rails, which indicates current concentration on the edge of armature resulting in the armature edge erosion. The current distribution in the railgun determines its efficiency and contact performance of armature/rail sliding. To improve the electromechanical performance, one type of armature with concave arc surface and saddle structure is designed by removing arch forms from the conventional flat armature and adopts saddle structure. Using a finite-element software to establish a 3-D perfect electric contact simulation models on static condition, the current density distribution of armature, inductance gradient of railgun, and erosion area of armature with various central angles φ was numerically simulated. The results show that: 1) in the nonaugmented railgun system, the increase in the central angle φ is beneficial to reduce the maximum current density value of contact interface and the erosion area of armature, but it is not conducive to the improvement on the electromagnetic launch system's inductance gradient and 2) in the augmented railgun system, the change of the central angle φ has little effect on the maximum current density value of contact interface and the electromagnetic emission system's inductance gradient, but the influence on the erosion area is obvious. Based on the above-mentioned work, the improved armature structures are proposed.