Effect of Geometric Parameters on Equivalent Load and Efficiency in Rectangular Bore Railgun

The electromagnetic launch system model provides a useful reference for the launch process and performance. Inductance gradient and resistance gradient of the rail, which reflect the equivalent load characteristics of the launcher, are related to shape, material of the rail, and other factors, making it difficult to characterize in the circuit model. Therefore, a method combining equivalent network with finite element analysis is proposed to solve this problem. A segmentation-based real-time trigger strategy is applied to the 4 MJ pulse power supply (PPS) system consisted of 28 modules to shoot the 0.15 kg armature on a 6 m long rail. The width, height of the rail, or separation between two rails increase individually from 20 to 180 mm. After computing the resistance and inductance gradients of the specific rail in ANSYS, the rapid system-level simulation is carried out in MATLAB-Simulink to deliver the railgun's performance. The results show that both the resistance gradient and the inductance gradient contribute to the launch efficiency. In order to obtain a larger inductance gradient, the width of the two rails should be narrower, the height should be shorter, and the separation between the two rails should be farther. Nevertheless, in the perspective of decreasing resistance gradient, the rail should be wider, taller, and farther. Although the resistance gradient increases with the decrease of height and width, the promotion in the inductance gradient has much more significant impacts on the electromagnetic force under the same geometric change. Therefore, for the sake of a higher launching efficiency, the rails should be narrower, shorter, and farther.