A miniature pump with a fluid dynamic bearing

This paper describes the development of a miniature pump having an impeller with an exit diameter of 24 mm supported with the motor rotor by a fluid dynamic bearing.Tests verify that the miniature pump is stable and quiet for rotational speeds larger than 4000 min-1.The three-dimensional turbulent flow in the entire pump flow passage and the laminar flow in the fluid dynamic bearing were then simulated numerically.The average pump performance was well predicted by the simulations.Both the tests and the simulations show that there is no obvious Reynolds effect for the miniature pump within the tested range of rotational speeds.The numerical results also show that the bearing capacity of the fluid dynamic bearing increases with the pump rotor rotational speed and the eccentricity ratio of the journal to the bushing.This pump is very compact,so it is a promising device for surgical use.