转速对水轮发电机推力轴承油膜特性的影响研究

Influence of Rotating Speed on Oil Film Characteristics of Thrust Bearing of Hydro-generator Unit

推力轴承的性能对水轮发电机组的能量转换效率和安全稳定运行至关重要,为此,采用数值模拟方法探究了某水电站水轮发电机组推力轴承不同转速工况下推力轴承油膜特性,分析了油膜内部的压力、速度和温度分布,明确转速对推力轴承性能的影响规律。结果表明,转速不会改变推力瓦表面的压力分布,但随转速的升高,最大压力与转速几乎呈线性变化的关系;转速上升使得推力瓦表面高温区向出油边远离主轴方向移动,且平均温差和最大温差均呈上升趋势。飞逸转速下推力轴承需要承受的压力远高于额定转速,且也要承受局部的高温,飞逸转速下最大温差超过40 K,容易造成轴瓦烧毁现象。研究结果为水电站推力轴承运行及优化设计提供了理论支撑。

The performance of thrust bearing is very important to the energy conversion efficiency and stable operation of hydro-generator unit.Therefore,the thrust bearing of a hydropower station was taken as the research object.The characteristics of thrust bearing oil film under different rotating speed conditions were studied.The pressure,speed and temperature distribution inside the oil film were analyzed.The influence law of rotating speed on the performance of thrust bearing was clarified.The results show that the rotational speed cannot change the pressure distribution on the thrust pad surface,but with the increase of rotational speed,the relationship between the maximum pressure and rotational speed is almost linear;The high temperature zone on the thrust pad surface moves away from the main shaft towards the oil outlet side with the increase of the rotating speed,and the average temperature difference and the maximum temperature difference show an upward trend.At runaway speed,the thrust bearing needs to bear much higher pressure than the rated speed,and also needs to bear local high temperature.The maximum temperature difference at runaway speed is more than 40 K,which is easy to cause bearing bush burning.The research results provide theoretical support for the operation and optimal design of thrust bearings in hydropower stations.