Abstract:The hydrodynamic lubrication performances of the hydrohybrid bearing which is lubricated by Na liquid in the twocircuit main loop Na liquid pump system were investigated.Through the hydrodynamic lubrication theory,the Na liquid lubrication bearing was modeled and analyzed using the advanced rotating mechanical dynamics analysis software package ARMD,and the special characteristics of the lubrication mechanism was revealed compared to the traditional oil or water lubricated bearing.For different external loads,different rotating speeds and different initial eccentricity ratios,the lubrication characteristic parameters and dynamic characteristics of the bearing were studied systematically.Research shows that external load,rotating speed and initial eccentricity ratio are the important factors on lubrication characteristic parameters.With the increase of external load and decrease of initial eccentricity ratio,the maximum pressure,power loss,temperature rise and the stiffness and damping coefficients are increased correspondingly,respectively;The minimum film thickness is opposite.The investigation lay solid foundation for the further study on dynamic characteristics of the Na liquid lubrication bearingnuclear main pump rotor coupled system.