Simulation on Side-Ejecting Characteristics of Metal Liquid Film in Electromagnetic Launcher

The Joule heat generated by the pulsed large current and the friction heat of the armature/rail (A/R) contact interface in the electromagnetic launcher causes the surface of the armature's tail melting. A part of the metal liquid film is deposited on the contact interface, a part of it left the barrel together with the armature, and the others was sprayed laterally, which damages the rails and the insulation. In order to lengthen the span of the launcher barrel's life, it is necessary to minimize the side-ejecting of metal liquid film. In this article, we obtained the 2-D Reynolds equation applicable to the metal liquid film. Using the finite-element software LS-DYNA and COMSOL, we have established a 3-D electromagnetic-elastic mechanics-hydrodynamics multiphysics coupling model considering the dynamic changes of magnetic pressure, liquid film's own acceleration, fluid pressure, and film thickness. We use this model to obtain the lateral film thickness, total pressure, and velocity distribution characteristics of the metal liquid film at any time. We have further studied the influence of armature velocity, stiffness of armature's tail, liquid film's own acceleration, and linear current density on the amount of side-ejecting of liquid film.