Analytic Damping Model for a Square Perforation Cell

摘要

A model for damping due to gas flow in a perforation cell is presented. The cell is a volume around a single hole of a perforated squeezed-film damper. Here, the perforations are holes with square cross-sections. The model is derived partly from analytic expressions for flow resistances of long microchannels, partly from FEM simulations. First, 2D simulations with a Reynolds solver are performed to solve the flow resistance in the air gap regime. Then, 3D Navier-Stokes simulations are performed to characterize the intermediate regime below the perforation, the perforation itself, and the gas outflow regime above the perforation. Slip flow boundary conditions are used to make the model applicable in MEMS structures.rnFitting techniques are applied and the flow resistance of the perforation cell is expressed as a set of simple equations. The model is verified against 3D FEM simulations of a perforated damper with 4...64 square holes.