水润滑轴承-转子系统的瞬态响应特性

阶跃、脉冲等非周期载荷具有幅值突变、变化剧烈的特点,当它们作用于滑动轴承主轴时,轴心位置可能会发生突变,造成轴承润滑状况的突然变化.海水淡化泵机组在启动、停机和转速变化时,可能会承受不同的瞬变载荷,为研究该泵水润滑轴承在瞬变载荷作用下的润滑情况及动特性的变化,使用Pro/E三维造型软件建立水润滑轴承-转子系统的流固耦合模型,应用计算流体动力学(CFD)技术和流固耦合(FSI)方法,分别对水润滑轴承-转子系统施加阶跃载荷、矩形载荷和三角脉冲载荷,分析不同时刻下转子的弹性变形对水润滑轴承周向压力分布、水膜承载力以及轴心位置的影响.结果表明:在瞬变载荷作用时,轴心位置、水膜承载力和最大水膜压力都有较大的变化并呈现一定的振荡过程;由于脉冲载荷作用时间有限,随着其消失,轴心位置仍收敛于原来的平衡位置,而阶跃载荷则使轴心位置收敛于新的平衡位置.

Transient response of water lubricated bearing-rotor system

Step and pulse loads are the transient loads with sharply and dramatically changing amplitudes. Therefore,when these loads are acted on a rotor,the axial centre of the rotor may be altered,resulting in a sudden change in bearings lubrication condition. A seawater desalination pump unit can experience different transient loads during startup,stopping and rotational speed variation. A fluidstructure interaction(FSI)model for the water lubricated bearing-rotor system in a seawater desalination pump unit was established to explore changes in lubrication condition and vibration dynamics under a transient load. Effects of rotor elastic deformation at different time instances on the circumferential pressure distribution,water film bearing capacity and axial centre position were analyzed by using CFD(computational fluid dynamics)and FSI methods when the rotor system was subject to step,rectangular and triangular pulse loads,respectively. The results showed that the axial centre position,file bearing capacity and maximum pressure in film can change greatly and exhibit a certain oscillation process under a transient load. Due to a pulse load applied in a limited period of time,once it disappears,the axial centre will restore its original balance position;for a step load,however,the centre will move to a new equilibrium position.