Numerical optimization of three-cavity magneto mercury reciprocating (MMR) micropump

Abstract

The operation of the three-cavity magneto mercury reciprocating (MMR) micropump, whose prototype were presented in an earlier companion paper, was numerically explored. In the three-cavity MMR micropump, three mercury slugs are moved by a periodic Lorentz force with a phase difference in three separate cavities. A consecutive motion of the slugs in their cavities transfer air from the inlet to the outlet. Two-dimensional OpenFOAM simulations were carried out to explore the influence of electric current excitation phase difference and back-pressure. The numerical simulations predicted the MMR micropump (with no valve) with a phase difference of $ 90^\circ $ and $ 120^\circ $ produces a mean pumping flow rate of 2.7 and 6.1 mL/min at a back-pressure of 10 Pa and maintains a maximum back-pressure of 17.8 and 20 Pa, respectively. However, it was found that there was a reverse flow at large back-pressures with an excitation phase difference of $ 90^\circ $ . The numerical results showed that employing a diffuser/nozzle valve with a length of 5 mm and an angle of $ 10^\circ $ improves the mean flow rate of the micropump with a phase difference of $ 90^\circ $ at a back-pressure of 10 Pa by 140% from 2.7 to 6.5 mL/min, and its maximum back-pressure by 125% from 17.8 to 40 Pa.

Keywords

• micropumps
• magnetohydrodynamics (mhd)
• lorentz force
• diffuser/nozzle valve
• vof
• openfoam