Study On Start-up And Shutdown Performance Of Sliding Bearing Of Large Turbo-generator

Sliding bearing is a common support system of large turbo-generator.During the start-up and shutdown of steam turbines,rubbing faults of dynamic and static components often occur.It is of great engineering significance to study the performance of sliding bearings during startup and shutdown.Firstly,this paper introduces the jacking oil system of large turbo-generator.The hydrostatic lubrication model of journal bearings is established by CFD,and the hydrostatic lubrication characteristics of journal bearings are calculated and analyzed.The results show that the film thickness increases approximately linearly with the jacking oil pressure within the range of commonly used oil pressure regulation in engineering.A CFD two-phase flow model for hydrodynamic lubrication of journal bearings is established,and the hydrodynamic lubrication characteristics of journal bearings during startup and shutdown are calculated and analyzed.The correctness of the model is verified by comparing with the experimental results.The performance of hydrodynamic oil film during start-up and shutdown is studied.The results show that the thickness of hydrodynamic oil film decreases and the maximum oil film pressure increases with the decrease of rotational speed.Considering the effect of jacking oil,a CFD two-phase flow model of hybrid lubrication of journal bearings is established to study the hybrid lubrication performance of journal bearings during start-up and shutdown.The results show that the pressure distribution trend and thickness of the film are approximately equal to the superposition of the hydrodynamic and hydrostatic lubricating film.During the start-up and shutdown process,the film thickness can be effectively increased by putting in the jacking oil.At medium and high rotational speeds,the influence of the jacking oil on the film thickness is small.Through the transfer matrix method,the influence model of bearing elevation adjustment on bearing performance and seal clearance during start-up and shutdown is established.Calculation and analysis are carried out.The results show that elevation will increase the bearing load and reduce the load of its adjacent bearings.Compared with high speed,the adjustment of elevation has a greater impact on the adjacent shaft seals at medium and low speed.