Hydroelastic Vibration of a Circular Diaphragm in the Fluid Chamber of a Reciprocating Micro Pump

Abstract

Reciprocating diaphragm micro-pumps are the most common type among indirectly–driven micropumps. This paper addresses the hydroelastic vibration of a circular elastic diaphragm interacting with the incompressible and inviscid liquid inside the cylindrical chamber with a central discharge opening. Taking into account axisymmetric vibration of the diaphragm, the fluid pressure exerted upon the plate is formulated using linear Bernoulli’s equation. The kinematic and compatibility conditions are incorporated into the elastic vibration of the circular plate to derive the governing eigen-matrix equation. Numerical results are presented for different materials for diaphragm (silicon and glass) and pumped liquid (water and methanol). Normal frequencies of the coupled system, wet mode shapes of diaphragm and fluid oscillation modes are presented in numerical simulations. It is seen that the hydroelastic interaction lowers the natural frequencies considerably. However, the wet mode shapes for diaphragm vibration are very similar to the dry mode shapes. Finally, the effects of chamber height and operating fluid density on the normal frequencies are illustrated for the lowest four modes.