PERFORMANCE ANALYSIS OF POROUS JOURNAL BEARING WITH SURFACE ROUGHNESS AND THERMAL EFFECTS

摘要

All tribological systems consisting of moving/rotating parts needs continuous lubrication, temperature control, reduced friction as means to ensure a smooth operation regime. The bearing installed with porous material impregnated with oil for which possess the advantage of no need to supply the oil from external source. This bearing has a stationary porous bushing whose inner diameter faces the bearing clearance, while the outer one faces a wrap-around reservoir. In the open literature, the studies related to the porous journal bearings have been mainly focused surface roughness without considering the thermal effects. The available studies related to the thermo hydrodynamic analysis of porous journal bearing neglected the surface roughness effects. Hence, the present study is aimed to predict the influence of surface roughness and thermal effects on static performance characteristics of porous journal bearing operation. The modified Reynolds equation governing the pressure field within fluid-film is developed by simplifying the Navier-Stokes equation. Solution of modified Reynolds equation is obtained using finite element method. The static performance characteristics are obtained by the integration of the pressure field that obtained from the solution of Reynolds equation. The influence of surface roughness and thermal effects permeability on static performance characteristics of porous journal bearing is studied. The load carrying capacity, fluid-film stiffness, damping coefficients, stability threshold speed margin and critical journal mass of smootressure field, h and rough porous journal bearings is constant up to permeability parameter 1E-02 for all surface orientations. The reduced static performance characteristics of porous journal bearing due to increased permeability can be compensated by the proper roughness. Stationary roughness and transverse roughness pattern combination provides maximum enhancement for the circumferential and axial pressure distribution, load carrying capacity.