Characteristics Research Of Upper Radial Bearings In Canned Reactor Coolant Pump

Upper radial bearing, as the key component of the canned reactor coolant pump, has an important influence on the safe operation of the reactor coolant pump. Upper radial bearing which is a water-lubricated tilting-pad journal bearing, is installed in the reactor coolant pump motor, and always runs in high-pressure environments with the temperature of the lubricant under 80℃. Few academic achievements on canned motor pump are established due to its special application field. A series of results of the study on the upper radial bearings'characteristics are presented in this paper.It is of significant importance to determine the factors that influence the tilting-pad bearings from the research achievements of former researchers. The domestic investigation of the methods, including those for water-lubricated bearings and stability analysis, to settle these factors have been taken out. Computer simulations on the pressure, capacity, attitude angle, lubricant flow and temperature are performed based on a set of factors such as bearing clearance, wide-diameter ratio, number of pads, geometry preload, eccentricity, lubricant inlet pressure, radial speed, protection offset rate, fulcrum distribution and pivot angle. The stiffness and damping coefficients of the bearing are also addressed and followed by a wide range discussion, resulting in the character pattern of the bearing.Finally, the influence of the above geometry configurations and operation parameters on the stability of the bearing is studied from the trajectories of the rotor, which are obtained from the dynamics equation of the rotor bearing system with the calculated stiffness and damping coefficients. The effects of the configurations and parameters of bearing on the critical speed of the system are carried out with the aid of a special MATLAB program.We can give references to the selection and design of the upper radial bearing based on the above analysis of the bearing characteristics, the trajectories and the bearing-rotor system's critical speed.