Comparative study on longitudinal momentum characteristics of L-type and I-type breech in railgun

Abstract

The position and magnitude of the longitudinal force during launch are very important to the design of electromagnetic railgun. This problem has become a hot topic of research for a long time. Previous experiments showed that most of the recoil force of the electromagnetic railgun locates at the breech. In order to study the stress distribution and momentum characteristics of the breech during launch. Based on Maxwell’s stress tensor, the momentum conservation equations for electromagnetic railgun were derived. Depending on whether the direction of the source current is perpendicular to the current direction in the rails, the breech is simplified and summarized into I-type and L-type structures. Then, the 3-d models of the two breeches were established and the launch process was simulated by finite element method. Some results such as the current density, magnetic field intensity and electromagnetic stress of the current injector plates and coaxial power connector under both models were obtained. The simulation results show that the longitudinal force on the breech is concentrated on the current injector plates. The longitudinal force on the power connector of L-type breech is much bigger than that of the I-type breech, up to nine times. Besides, different structures of the breech will not affect the launch performance of the railgun.