Flow-thermal Analysis And Optimization Of Thrust Bearing For Shaft Seal Type Nuclear Coolant Pump

The nuclear coolant pump is the heart of the nuclear power plant and the only rotating equipment in the nuclear island.It is required to be able to operate without failure and stably for a long time.It is the only key equipment of the nuclear power system that cannot be independently developed in China.During operation,the thrust bearing bears the rotating parts of the nuclear coolant pump unit and the bidirectional axial load,which is the core part to ensure the long-term safe and stable operation of the nuclear coolant pump.The temperature distribution and control of thrust tile are very important to ensure the bearing capacity and stability of the bearing,its temperature distribution not only related to the corresponding oil film temperature,but also closely related to the flow field between the thrust tiles and the flow field around the tile.How to analyze the flow field and temperature distribution of the bearing,optimize the geometric parameters of thrust tiles and flow channels to ensure the requirement of bearing temperature control during operation,to improve the safety and stability of the bearing is one of the key technologies in the independent research and development of the nuclear coolant pump.Combining with the Science and Technology planning project(2017JY0047)undertaken by our university and the project entrusted by enterprises and institutions(172250).Taking a new generation of shaft seal type nuclear coolant pump thrust bearing as the research object,analysis the characteristics of flow field and temperature distribution of thrust bearing of shaft seal type nuclear coolant pump,explores the influence of the changes of geometrical parameters of the flow channels between the thrust tiles on the cooling performance of the bearing,and then propose the design optimization schemes.The main research and conclusions are as follows:(1)According to the structure form and operation characteristics of thrust bearing of shaft seal type nuclear coolant pump,analyze the factors affecting the distribution of temperature during operation of the bearing and the influence of the geometric parameters of the flow channels on lubrication,cooling and bearing characteristics.The optimal design strategy and the key optimization problems of the thrust bearing of the shaft seal type nuclear coolant pump are determined to ensure the temperature control of the bearing in the process of operation.(2)According to the operation characteristics and structure of the thrust bearing of the nuclear coolant pump,explored a numerical simulation method of full flow channel for thrust bearing of nuclear coolant pump.(3)Combining with the nuclear coolant pump thrust bearing oil film flow characteristics and physical parameters,used different calculation strategies to calculate the temperature of the bearing oil film,and verified the reliability of the result.(4)Calculate the full flow channel model,analysis the shortcomings of bearing flow distribution from the characteristics of flow field,combined the flow field with the temperature field to prove the reliability of conclusions.Result shows the insufficient heat transfer of hot and cool oil between thrust tiles.There is the dead oil area which is easy to cause heat accumulation,the high temperature area is large,temperature of bearing is too high.(5)Under the premise of ensuring the stability and bearing capacity of the thrust bearing of the nuclear coolant pump,taking the improvement of temperature distribution as the optimization objective,the geometric parameters of flow channels were taken as the design variables.Proposed four kinds of bearing optimization schemes according to the initial design.Comparing and analyzing the flow field characteristics and temperature distribution of each optimization scheme.Result shows,changes on the geometric parameters of the channel can not only increase the flow of lubricating oil between the tiles,but also is very important to change the characteristics of the bearing flow field.The four optimized thrust bearings can reduce heat accumulation and improve the temperature distribution by eliminating the hot oil backflow and the cold oil flow into the rotating chamber.