Pumping-velocity variation mechanisms of a ferrofluid micropump and structural optimization for reflow inhibition

Ferrofluid micropumps have become an important development in the field of micropumps because of their self-sealing, self-lubricating, and integral properties. To further explore the relationship between pumping velocity and pumping period, in this study, an overlapping grid technology is coupled with a model with six degrees of freedom to perform numerical analyses on the inlet- and outlet-velocity pulsation characteristics of a micropump. The results show that the inlet and outlet velocities of the micropump are periodic and region-dependent and are not affected by backpressure and rotating speed. The rotating speed determines the pumping speed of the micropump, and the ratio of the rotating speeds under two working conditions is equal to the ratio of the pumping speeds. In a laminar flow range, where the Reynolds number is 8, the outlet velocity exhibited a small lateral pulsation (of 10−4 orders of magnitude). The backpressure and pumping fluid at the outlet pressurized by the micropump are key factors that induce the backflow of the micropump. To solve the backflow problem, a double-piston micropump structure that is effective in restraining backflow, without requiring additional mechanical devices, and retains the compactness and simplicity of the micropump is proposed.