Research On Oil Film Characteristics Of Thrust Bearing Of Plastic Shingle For Hydropower Unit Based On Finite Element Analysis

Thrust bearing is the core component of water turbine generator unit to bear axial load.In the operation of the unit,the oil film is damaged under the influence of complex factors,and the surface of thrust tile is prone to appear wear phenomenon,which directly affects the using time of thrust bearing and the normal operation of the unit.Therefore,it is of great significance to carry out the research on the oil film characteristics of thrust bearing.In this paper,the research object is the plastic pad thrust bearing of no.5 unit of fengman Power Plant,and its oil film characteristics are studied from shallow to deep.First,without considering the elastic deformation of thrust tile,on the basis of hydrodynamic pressure lubrication theory,the simultaneous equation,oil film thickness of oil film pressure control equation and viscosity-temperature equation,plastic tile thrust bearing of the numerical model is established,using the finite difference method to simplify the numerical model,using the MATLAB program to calculate,the successive overrelaxation iteration method is adopted to solve the oil film pressure and oil film thickness distribution.It is found that the oil film pressure increases slowly from the oil inlet edge,and the maximum oil film pressure is located at the oil outlet edge of thrust tile,while the oil film pressure gradient decreases rapidly at the oil outlet edge.The oil film thickness gradually decreases from the oil inlet edge to the oil outlet edge.Secondly,the influence on elastic deformation of thrust pad is fully considered.COMSOL Multiphysics is used to establish a THREE-DIMENSIONAL dynamic pressure lubrication model of thrust pad.The physical field,boundary conditions,loads,constraints and mesh division of thrust bearing are set up.The influence of different factors on the oil film characteristics of thrust bearing under stable running state is analyzed emphatically.It is found that the maximum pressure of oil film increases greatly with the increase of load during this unit operating.With the increase of oil temperature,the viscosity of lubricating oil decreases sharply,resulting in the thickness of the oil film gradually thinning from the oil inlet edge to the oil outlet edge and the weakening of the carrying capacity of the oil film;When the tilt Angle increases in a certain range,the oil film pressure decreases first and then increases significantly,which indicates that there is an optimal tilt Angle,which can make the oil film thickness distribution reasonable,and is conducive to increase the bearing capacity of the oil film.When the unit speed reaches the rated speed,the oil film thickness of the oil outlet edge of the thrust pad is stable around a certain value.Finally,in order to realize on-line monitoring towards oil film thickness of thrust bearing of unit and facilitate operation and maintenance personnel to observe oil film thickness in real time,an online monitoring system of oil film thickness is designed.Based on eddy current sensor,data collector and upper computer,an online monitoring system of oil film thickness of thrust bearing was constructed to realize real-time monitoring of oil film thickness of thrust bearing.Based on the continuous operation data of Fengman No.5 engine,analyze the influence of the following three factors,namely unit speed,thrust pad and unit load on oil film thickness,and draw the relationship chart between different influencing factors and oil film thickness,which can be used to monitor the change trend of thrust bearing oil film and ensure the safe operation of the unit.The numerical model,3d model and analysis method established in this paper,as well as the research results obtained by the online monitoring system of oil film thickness,can provide theoretical basis and reference for the analysis of oil film characteristics and online monitoring technology towards oil film thickness of plastic thrust bearing in the future.