Helically Wound Linear Induction Pump for Molten Nonferrous Metals

The topology and characteristics of the basic categories of linear induction pumps are reviewed, and the concept, design, and performance of a novel type of pump for molten nonferrous metals are presented¿the helically wound linear induction pump (HWLIP). The configuration is such that the windings follow a helical path about the axis of the pump, and three-phase excitation produces a bore field having both rotational and translational components. A HWLIP was designed to maximize the thrust component and was constructed with a set of six 5000-A solid copper water-cooled helical coils in a stack of laminations. The magnetic, electrical and mechanical characteristics were experimentally evaluated. It is shown that molten metal is essentially under no-load conditions in rotation, and if high angular velocities are allowed to occur, the performance of the pump is seriously degraded. An electromagnetic or mechanical means of spin suppression is required to make the HWLIP a useful molten metal pump for industrial applications.