Flow-fieldanalysisand Structure Optimization Of Oil Sumpin Thrust Bearing Of Large-scale Water Turbine Generator

In the hydroelectric generating set, the thrust bearing under huge axis push is one of the key components which determine whether the unit can be operating safely and reliably. With the increase of the capacity, size and structure complexity of the unit, it is primary to ensure the thrust bearing run safely and reliably in the actual operation. The reliability of thrust bearing on the operation mainly depends on the support of the bearing bush and the cooling structure of lubricant, so it is of great significance to study the internal flow filed of oil sump under different cooling structures.Thrust bearing is a mechanical component which is based on bearing principle by liquid lubricant. Under a certain rotating speed, the normal operation is sustained by the wedge shaped oil film due to the viscosity of lubricant. As a result, the shape, size and other parameters of wedge shaped oil film can directly influence the operation and performance of the thrust bearing. Based on the sub-project of project for the 1000MW thrust bearing of hydroelectric generating units, the analysis of the internal flow field of oil sump and capacity of the thrust bearing is carried out through changing the shape and size of wedge shaped oil film and the speed of rotating components.Firstly we briefly introduced the classification and the theories of thrust bearing. Then the physical three-dimensional model is established by UG NX4.0, the mesh and boundary type is generated by Gambit, and the boundary conditions, numerical methods, turbulent models, wall are set in Fluent. In the simulation, standardκ-εmodel, steady and separate solver and iterative solution are used. After the calculation, we obtained the characteristics of internal flow field for the thrust bearings with five different structures, to understand the flow trend and distribution. According to the above results, overall pressure of 1/12 model,velocity distribution of inlet and outlet, and the capacity of thrust bearing under different condition were obtained . Finally the optimization of the design of thrust bearing was made through the comparative analysis of the relationship between the capacity of thrust bearing and clearance dimension, size of clearance, speed of rotating parts ,as well as, changing of capacity of the same clearance for different structure of thrust bearing, respectively.