Influence of lubricant on the motion of a body in an electromagnetic railgun accelerator. II. Hydrodynamics of a conducting lubricant

Abstract

The flow of a liquid conducting film in the gap between the rail and the metallic projectile (armature) in a railgun is considered. In contrast to the usual problems in the theory of the hydrodynamics of lubricants, the statement of the problem here takes into account such additional forces acting on the liquid as the ponderomotive force and the inertial force arising as a consequence of the accelerated motion of the armature. As a result, even in the case of a gap of constant width not only is the existence of flows with negative velocities possible, but also of flows with negative flow rates. An analytical solution of the problem is obtained with the convective terms neglected. The influence of the convective terms is estimated by integrating the lubrication equations numerically. Primary attention is devoted to a calculation of the lubricant flow rate, viscous dissipation in the liquid layer, and the pressure distribution along the gap. Calculations are performed for specific cases of linearly expanding and linearly narrowing gaps.