Study on performance of tilting pad journal bearings under wear condition

Key words:  tilting pad journal bearing  pad wear  thermo-hydrodynamic lubrication  computational fluid dynamics  dynamic grid technology

Abstract:

A three-dimensional thermo-hydrodynamic (THD) model of tilting pad journal bearings (TPJBs) was established by using the computational fluid dynamics (CFD) method, aiming at the rotor-TPJBs system with wearing failure under the condition of start-stop or external interference. The flow field was coupled with the motion of the shaft and the pads by using a self-developed dynamic grid program, and the transient calculation of lubrication flow field of TPJBs was carried out. The hydrothermal lubrication properties of TPJBs before and after wearing were studied. The pressure distribution, temperature distribution, loading capacity and eccentricity of TPJBs under different wearing depths were analyzed and compared. The results show that there is a high pressure zone in each pad of TPJBs, resulting in the hydrodynamic effect. The wearing of the pad destroys the continuity of pressure and temperature on the surface of the pad and results in the decrease of the local pressure and temperature. With the increase of the wearing depth, the loading capacity of the bearing decreases gradually, and its eccentricity increases continuously.