Comparison of Railguns through Numerical Simulations

Abstract

Up to date, the armature transition is still a big problem in railgunnery. Many kinds of mechanism were proposed by researchers to predict or explain armature transition phenomena. And many types of railgun were invented. In this paper, three types of railgun, including simple railgun, parallel-augmented railgun and muzzle-fed railgun, are investigated with numerical simulations. Since current density is the decisive factor to transition velocity, this study focuses on the current distribution in armature. The inductance gradient of railgun and magnetic field distribution are also investigated. In order to simplify simulations, rails and armature are considered in each simulation, and armatures of railgun are same. The Maxwell 3D modular of Ansoft corp. was utilized as the program code. The simple railgun is selected as the benchmark, and the other two types were compared with it. In the simulation of parallel-augmented railgun, two current sources (500 kA, 60 Hz) were connected to inner rails and outer rail independently. In muzzle-fed railgun simulation, the same current source as in simple railgun was connected to rails. Based on simulation results, conclusions are drawn that augmented railgun has the highest inductance gradient and the largest launcher efficiency. But the current density at rear part of armature is larger than that of simple railgun if the currents flowing through inner rails and outer rail are equal. The inductance gradient of muzzle-fed railgun is the smallest, but the current density at armature shoulder is the largest. Projectiles of muzzle-fed railgun will face the greatest magnetic flux density.