The Numerical Analysis Methods of Electromagnetic Rail Launcher With Motion

To solve the sliding electrical contact problems, it is necessary to take into account the interface conditions of magnetic field intensity H and magnetic flux density B and also those of electric field strength E and current density J when the armature is in contact with the rail. As the interface condition of E is not implicitly included in the simplified weak forms of governing equations, the discontinuous electric scalar potential φ is used in the nodal element, the continuous φ in the edge elements, and meanwhile v · A = 0 serves as a gauge condition by tree technique to deal with the interface condition of E. The penalty method is adopted to set up the coupling equations for the interface conditions and the boundary conditions of current inlet surface. The use of the above methods leads to the establishment of the finite-element equations for the motion in the conditions of the nodal and edge elements and to the construction of the corresponding numerical model. The comparison of the result obtained from the model with the result of calculating the eddy current of the 2-D or 3-D electromagnetic rail launchers proves the proposed methods to be feasible and effective.