Temperature distribution and heat generating/transfer mechanism of the circular bilayer porous bearing for thermo-hydrodynamic problem

•The temperature and pressure distributions are not consistent inside the porous bearing.•The circumferential velocity is the major contributor to the temperature rise.•Oil film shearing is the heat source of the bearing system.•The heat is gradually transferred from oil film to porous medium through the heat conduction and convection. Circular porous bearing is a widely used self-lubricating bearing structure but it exhibits higher temperature rise in bearing system — heat produced cannot be dissipated in time — which leads to poorer lubricating performance and makes it difficult to use in complex working conditions. We establish the thermo-hydrodynamic lubrication model of circular bilayer porous bearing in polar coordinates coupling with the fluid pressure and heat transfer equations, and reveal the fundamental origin of the heat generating and its transfer mechanism. The results indicate that the circumferential velocity is the major contributor to determine the temperature distribution, and the oil film shearing causes temperature rise of the bearing system which is gradually transferred from oil film to porous medium through the heat conduction of porous metal and the convection of fluid. Thus, the temperature in the oil film region is higher than that in the porous bearing. In the vertical direction, the temperature rises first and then decreases from the bearing bottom face to the counterpart surface, While in the radial direction, the temperature increases gradually from the inner radius to the outer radius. We find that the highest temperature of the bearing system occurs at the minimum film thickness of the external ring face in the oil film region. The numerical model is verified by comparing the experimental and numerical results, and the numerical accuracy of the lubrication performance has been improved after considering the thermal effect. Our results can be employed to control the oil film temperature and exert a better lubricating performance.