Three dimensional thermohydrodynamic analysis of multi-lobed bearings

Abstract

An approach for three dimensional Therinohydrodyiiamic analysis of multi-lobed journal bearings is presented. The generalized Reynolds equation solution yields the Dressure distribution in the axial and circumferential directions. The energy equation is three dimensional and takes into account the convection and dissipation in axial and circumferential directions. Heat conduction through the fluid film ill axial, circumferential and cross-film direction is considered. Variation of viscosity in all three directions is considered. A finite element method is used to solve the associated partial differential equations and the associated boundary conditions. In order to obtain a stable and realistic temperature distribution, three dimensional finite element upwinding technique is developed and incorporated whenever the convective term is dominant. Reynolds boundary condition is used to determine the cavitation boundary and thermal cavitation model is applied in that region. Location and magnitudes of maximum temperature in the bearing and the pressure profiles are obtained and compared to existing data in literature. Comparison is also irlade between results obtained using optimal and full upwinding versus no upwinding. Dynamic coefficients of bearing using variable viscosity model are derived and compared to isoviscous results-Thermohydrodynamic simulation of multi-lobed journal bearings is presented using more realistic three dimensional boundary conditions on the model.