Finite Element-Boundary Element Method Based Simulations of Electromagnetic Railgun in Augmented Configurations

When dealing with electromechanical system modelling, numerical challenges are inevitable. Especially when working with moving conductor problems, such as rotational or linear motors, special care needs to be taken for the air-gap region. Railguns air region is one more addition to this modelling problem. The air region necessitates either remeshing or a custom mesh topology. In addition, the production of air mesh for conductors with complicated shapes has its own difficulties. The air mesh requirement may be reduced by using the finite element-boundary element (FE-BE) technique. Boundary elements for air mesh and finite elements for conductors allow for the creation of models with moving conductors and makes model production easier and quicker. This paper investigates the changes observed in the railgun's electrical and mechanical parameters through the finite element-boundary element simulation approach when the geometry of the augmentation rails in a railgun is changed. Tapering and filleting are two geometry changes implemented on the augmenting rails of an electromagnetic railgun. Designed railgun variants are investigated using LS-Dyna software. A new formulation for breech voltage in augmented electromagnetic railguns is derived to calculate barrel efficiency. Four configurations of augmented electromagnetic railguns are analyzed, emphasizing force profile, inductance gradient, and motional-emf ( $iL^{\prime }v$ ). One of the new configurations has resulted in an improvement in the force profile during the initial stages of the launch by 8.8%, and the armature's final muzzle velocity has improved by 7%.