Prediction And Improvement Of Operating Characteristics Of Sliding Thrust Bearing For Large Motor

Thrust bearing is an important component of large vertical pump unit,which plays a critical role in bearing the axial load of the unit and supporting the normal rotation of the shaft.It is of great significance to the safety,stability and reliability of the pump unit operation.The lubrication of thrust bearing is a typical strongly-coupled thermal-hydrological-mechanical process.Based on ANSYS Workbench,the thermo-elasto-hydro-dynamic(TEHD)lubrication characteristics of tilting pad thrust bearing are analyzed by employing a bidirectional three-dimensional thermal-fluid-solid interaction method.The lubrication characteristics of PTFE and Babbit thrust bearings under rated operating conditions have been investigated and compared.The influence of operation parameters and furring condition of oil cooler on the lubrication performance of PTFE bearings has been investigated,a method of selecting cooling water flowrate reasonably based on its inlet temperature and the maximum allowable temperature of thrust pad has been put forward.The operating state of thrust bearings with both rigid and elastic support has been investigated when the tile surface height is different.The main research results are as follows:(1)The temperature prediction of thrust bearing pad is accurate by numerical calculation.The difference between measured temperature and measured temperature is less than 1?.The high temperature zone of the two different bearing pad surface is near the oil outlet side and the outer-diameter side.Compared with Babbitt bearing,the high temperature zone of PTFE bearing is closer to the oil outlet side.The maximum temperature of PTFE pad surface is about 8.3? higher,and the difference between the temperature of temperature measuring point and the maximum temperature of pad surface can be significant,which is 23?.Under the same working conditions,the difference between the temperature of the measuring point and the maximum temperature of the Babbit pad surface is only 5.6?.(2)Thermoelastic deformation makes the PTFE pad surface concave,while the Babbit pad surface convex,the deformation of the runner of the two thrust bearings is convex in the middle and upward around.The minimum oil film thickness of the two bearings is similar,the oil film thickness distribution of the PTFE thrust bearing is more uniform and reasonable,the pressure distribution of PTFE pad surface is more uniform,and the maximum pressure is reduced by 18.3%.The PTFE thrust bearing has better load-bearing performance,but the friction power loss is about 12.44%higher than that of the Babbitt bearing.(3)When the inlet temperature of oil cooler cooling water is known,the minimum required cooling water flow can be determined according to the maximum allowable temperature of thrust pad.When the inlet temperature of cooling water is 21?,the minimum required cooling water flow is only 20.51%of the rated cooling water flow.When the inlet temperature of cooling water is constant,the minimum required cooling water flow of oil cooler increases with the increase of scaling thickness.When the inlet temperature of cooling water is 21?,the scale layer with 0.1 mm thickness increases the minimum cooling water flow by 27.58%compared with that without scaling,and the scale layer with 0.5 mm thickness increases the minimum cooling water flow by 45.73%compared with that without scaling.(4)The maximum temperature and the maximum pressure on the pad top surface increase with the increase of thrust load,while the minimum oil film thickness,average oil film thickness and standard deviation of oil film thickness decrease with the increase of thrust load.When the difference of the tile surface height is 5 ?m,the performance of thrust bearing supported by disc spring with 570 N/?m single pad stiffness increases significantly compared with that of rigid thrust bearing.For elastic support thrust bearing,the non-uniformity of force between bearing pads decreases by 10%,the maximum temperature of thrust pad decreases by 0.8?,the temperature difference between thrust pads decreases by 0.97?,and the minimum oil film thickness increases by 5.71%.