Abstract:The variations of hydrodynamic pressure and film thickness with waterinoil lubricants during startup were studied,the effects of initial conditions and impact load on the lubrication characteristics of journal bearing were analyzed.The results show that during the period of startup,film pressure is increased quickly to peak and then decreased to a steady state,temperature is continuously increased before reaching steady state,and the film thickness on the bearing pads is decreased with the increase of pressure,the clearance on the non bearing pads is increased.The effects on the lubrication characteristics of bearings by different initial loads,temperatures and speeds are remarkable.Impact load can lead to the impact of film pressure,and also has influences on temperature and film thickness.