Meniscus Shape and Splashing of Magnetic Fluid in Magnetic Fluid Seal.

Magnetic fluid splashing due to high-speed rotation of a seal ring was experimentally investigated in relation to gap length and magnetic field strength around the gap to be sealed. Meniscus shape deformation owing to fluid rotation was accurately observed by means of its silhouette shading laser light illuminated behind the meniscus. The deformation was found to occur in three stages. In the first stage, meniscus static width shrank, while meniscus rotating height remained nearly unchanged. In the second stage, these relations were reversed. Finally, abrupt total shrinkage occurred accompanied with splashing. Splashing initiation was found to strongly depend on the magnetic field gradient at the top of the rotating fluid. This provided a simple and useful parameter to determine the splashing initiation.