Multiparametric Investigation of Thermal Limitations in a Rapid-Fire Multirail Railgun Powered by a Pulsed MHD Generator

The operation of rapid burst firing multi-rail railguns was analyzed by numerical simulation using coupled 2-D and 3-D nonstationary formulations. In the calculations, a Sakhalin-type pulsed magnetohydrodynamic generator is assumed as a power source for the launcher. Launchers with three and five pairs of parallel rails connected into a series electrical circuit are considered. The simulation was performed for different numbers of projectiles in a burst and for different projectile masses. It is established that a major factor limiting the operation of launchers in such modes is the heating of the rails. It is shown that the rate of rail heating is determined by the inhomogeneity of the current density distribution along the rail section due to the nonstationary diffusion of the magnetic field into the rails and by the velocity skin effect. It has been shown previously that the maximum heating of the rails occurs in regions located outside the launcher channel provided that the width of the outer rail extends beyond the section of the launcher channel. We investigated the possibilities of reducing the heating of rails in these regions using rails of different widths in the rail launcher channel, using rails of different materials and rails with inhomogeneous electrophysical properties, and using armatures of different materials. The calculations show that with an optimal choice of the material and structure of the rails and the armature material corresponding to this structure, multirail launchers 5–6-m long can provide a projectile velocity of 2–2.5 km/s in a burst of 10–16 projectiles with masses of up to 800 g at a firing rate of 200–300 shots per second with no melting of the rails in the launcher channel.