Research On The Vibration Of The Shaft System And The 3D TEHD Lubrication Of The Thrust Bearing In The Pumped Storage Power Unit

Under the influences of hydraulic,mechanical and electromagnetic factors,the pumped storage power units usually have shaft vibration problems especially with the serious hydraulic vibration during condition conversion processes and off-rating conditons.As the key component of the units,thrust bearings often fail to the wear during the frequent starts and stops which directly affects the safe and stable operation of the units.Its lubrication is actually a fully coupled thermal-hydrological-mechanical processes.Therefore,it is significant to research the influences of the hydraulic,mechanical and electromagnetic factors on the dynamic characteristics of the shaft of the pumped storage power unit and the thermal-elastic-hydraulic-dynamic(TEHD)lubrication of the thrust bearing.Thus,this thesis has done some research on the following three aspects:Firstly,the Finite Element Method for rotor dynamics was used to study the influences of the rack system,unbalanced the electromagnetic pull of the generator and the stiffnesses of the sliding bearings on the mode characteristics of the shaft system of the PSP units,and to compute the shaft dynamic responses in the turbine steady state condition and during the start and stop processes.The shaft dynamic model considered both unbalanced electromagnetic pull and rack systemswhich can describe the mechanical electromagnetic coupled relationship more accurately.The circumferential non-uniform pressures in the crown and ban clearances induced by the unsteady flow in the turbine are the main cause of the unbalanced hydraulic force.The predicted radial swings and axial vibrations in the steady and transient processes are consistent with the measurements which compensated the deficiency of the site tests.The fluid-structure-thermal interaction method was used to investigate the TEHD lubrication of the bidirectional tilting-pad thrust bearing of the PSP unit.The additional artificial damping was applied to slow the movement of the pad and thrust block during the transient iterative calculation to ensure the calculation convergence.The mechanism of the adaptive tilt of the pad and the characteristics of the heat dissipation in the oil film were analyzed which help to obtain the hot oil transfer factor for the film and the convective heat transfer coefficients for the pad free surfaces.The influences of the radial and angular eccentricity ratios of the pad support position on the lubrication were emphatically discussed and then concluded an optimal support position.The transient TEHD analysises on thrust bearing during the start and stop processes of the turbine and pump condition were conducted.The research analyzed the hydrostatic lubrication characteristics during the high pressure oil jacking mode,discussed the change regularity of the oil film pressure,temperature and thickness with the rotational speed and found that the tilt angle of the pad lags behind the rotational speed.The rapid temperature rise during the speed up process leads to the serious transient thermal deformation on the pad,while the rapid temperature decline during the speed down process help reduce the transient thermal deformation.This thesis reveals the transient TEHD mechanism of the thrust bearing and provides guidance on the optimization design and the safe operation of the thrust bearings for the PSP units.