大型水轮机组推力轴承油膜厚度在线监测研究

Research on oil film thickness online monitoring for thrust bearing of large hydraulic generating units

油膜厚度是反映推力轴承运行状态的重要参数,对油膜厚度进行实时在线监测有助于实现推力轴承的稳定运行。以某大型水轮机组推力轴承为例,结合其润滑流体的雷诺方程和油膜厚度方程,利用有限差分法分析了不同载荷和不同转速下推力轴承油膜厚度和压力分布的变化规律,并设计了一种油膜厚度实时在线监测方法。理论分析结果表明,当转速一定时,推力轴承油膜厚度先随着载荷的增大而增大,达到峰值后,随着载荷的增大而减小;当载荷一定时,油膜厚度随着转速的增大而增大。理论分析结果与该水轮机组推力轴承油膜厚度的在线监测数据完全吻合,验证了提出的油膜厚度在线监测方法的可靠性,为推力轴承运行状态的诊断提供了科学依据。

The oil film thickness is an important parameter that reflects the operating status of thrust bearings. The real-time online monitoring of the oil film thickness is helpful to achieve stable operation of thrust bearings. Taking the thrust bearing of a large hydraulic generating unit as an example,combining the Reynolds equation and the oil film thickness equation of its lubricating fluid, the finite difference method was used to analyze the change law of the oil film thickness and pressure distribution of the thrust bearing under different loads and different rotational speeds, and a real-time online monitoring method of oil film thickness was designed. The theoretical analysis results showed that when the rotational speed was constant, the oil film thickness of the thrust bearing first increased with the increase of the load, and after reaching the peak value, the oil film thickness decreased with the increase of the load. When the load was constant, the oil film thickness increased with the increase of the rotational speed. The theoretical analysis conclusion was in complete agreement with the online monitoring data of oil film thickness for the large hydraulic generating unit. The reliability of the proposed online monitoring method of oil film thickness is verified, which provides a scientific basis for diagnosing the operating state of the thrust bearing.