Study on Flow and Lubrication Characteristics of Metallic Liquid Film Under Melting in Electromagnetic Launch

During electromagnetic launch (EML), interfacial frictional and Joule heat instantaneously melt the contact materials, forming a diverging metallic liquid film. Classical lubrication theory indicates that it is difficult to maintain the positive pressure required for hydrodynamic lubrication when liquid flows through a diverging gap. To reveal how melting affects the flow and lubrication of this film, a liquid-film flow model with melting at the armature surface is established. From the Navier–Stokes equations, a generalized Reynolds equation with inertial correction and melting source terms is derived under the lubrication approximation, discretized by the finite volume method, and solved by the tridiagonal matrix algorithm. The effects of melting velocity on pressure distribution, velocity profiles, streamlines, shear stress, and flow distribution are systematically investigated. The results show that the melting source suppresses the negative-pressure region and eliminates the large-scale backflow near the armature surface. A reasonable melting-velocity range exists: below its lower bound, the film cannot maintain positive pressure and is prone to backflow; within the range, it sustains positive pressure and stable transport; above its upper bound, reverse outflow appears near the leading edge. Melted liquid is mainly discharged through the trailing edge, while the leading-edge flow decreases with increasing melting velocity. These findings provide a theoretical reference for analyzing the flow and lubrication of the armature–rail interface liquid film.