Multiphysics Analysis of Transient Muzzle Arc Evolution and Arc-Induced Dynamic Disturbance in Electromagnetic Rail Launch

To investigate the transient muzzle arc and its influence on the post-exit dynamics of the armature in electromagnetic rail launch (EMRL) systems, a bidirectionally coupled multiphysics simulation framework integrating ANSYS Maxwell and Fluent is developed. A 10 × 10 mm scaled-caliber launcher with a 1.9 g aluminum-alloy armature is considered to quantitatively characterize the coupled evolution of the electromagnetic field, temperature field, and arc-induced flow field after armature–rail separation. The results show that the air-gap breakdown arc reaches a peak temperature of approximately 35,873 K at the early post-exit stage, producing concentrated thermal loads near the armature tail and rail leading edges. The rapid spatial expansion of the arc further redistributes the current density and distorts the local electromagnetic field, resulting in asymmetric Lorentz forces acting on the unconstrained armature and pronounced transient acceleration disturbances along multiple axes. Comparative simulations with and without a bypass arc chute demonstrate that the additional conduction path promotes rapid current commutation and suppresses the spatial expansion and persistence of the muzzle arc. Consequently, the arc-induced electromagnetic disturbance is substantially reduced, and the armature acceleration responses converge toward zero within approximately 50 μs after muzzle exit. These results establish a quantitative link between transient arc evolution, electromagnetic-field distortion, and post-exit armature dynamic disturbance, and demonstrate the potential of bypass arc chutes for simultaneously mitigating muzzle thermal loading and improving post-exit flight stability in EMRL systems.