Dynamic Performance of an Externally Pressurized Porous Thrust Bearing Employing Different Pocket Shape

Abstract

The use of porous facing/layer in fluid film bearings offers some unique advantages such as self-lubricating properties (acting as lubricant reservoir), compactness, economical over conventional bearing etc. This article presents a numerical simulation of an externally pressurized porous thrust bearing. The collective effect of permeability of porous facing and lubricant supplying pocket shape has been investigated on steady-state and dynamic performance indices of bearing. Flow governing equation i.e. Reynolds equation, Darcy’s Law and fluid flow equation (through an orifice device) has been solved simultaneously (using finite element approach) to compute fluid film pressure distribution. The bearing performance indices i.e. film reaction force, lubricant flow, stiffness and damping parameters are computed as a function of permeability and geometric shape of pocket. It has been reported that high value of permeability of porous facing have an adverse effect on the load supporting capacity, lubricant flow, stiffness and damping parameters of the bearing. There exist a range of permeability value ((2.2~3)10-14 m2; ψ = 0.001~0.01) within which the adverse effect of using porous facing can be partially reduced/mitigated by appropriate selection of pocket shape (Circular and square) in thrust pad.

Keywords

• porous thrust bearing
• permeability
• pocket geometry
• fem